/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.7.5.  By combining all the individual C code files into this 
** single large file, the entire code can be compiled as a one translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% or more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other
** programs, you need this file and the "sqlite3.h" header file that defines
................................................................................
*/
#ifndef SQLITE_DEFAULT_WAL_AUTOCHECKPOINT
# define SQLITE_DEFAULT_WAL_AUTOCHECKPOINT  1000
#endif

/*
** The maximum number of attached databases.  This must be between 0
** and 30.  The upper bound on 30 is because a 32-bit integer bitmap
** is used internally to track attached databases.
*/
#ifndef SQLITE_MAX_ATTACHED
# define SQLITE_MAX_ATTACHED 10
#endif


................................................................................
** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.5"
#define SQLITE_VERSION_NUMBER 3007005
#define SQLITE_SOURCE_ID      "2011-01-28 17:03:50 ed759d5a9edb3bba5f48f243df47be29e3fe8cd7"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_WAL              0x00080000  /* VFS only */



/*
** CAPI3REF: Device Characteristics
**
** The xDeviceCharacteristics method of the [sqlite3_io_methods]
** object returns an integer which is a vector of the these
** bit values expressing I/O characteristics of the mass storage
** device that holds the file that the [sqlite3_io_methods]
................................................................................
** ^(The [SQLITE_FCNTL_SYNC_OMITTED] opcode is generated internally by
** SQLite and sent to all VFSes in place of a call to the xSync method
** when the database connection has [PRAGMA synchronous] set to OFF.)^
** Some specialized VFSes need this signal in order to operate correctly
** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most 
** VFSes do not need this signal and should silently ignore this opcode.
** Applications should not call [sqlite3_file_control()] with this
** opcode as doing so may disrupt the operation of the specilized VFSes
** that do require it.  
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
................................................................................
** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
** Day Number multipled by 86400000 (the number of milliseconds in 
** a 24-hour day).  
** ^SQLite will use the xCurrentTimeInt64() method to get the current
** date and time if that method is available (if iVersion is 2 or 
** greater and the function pointer is not NULL) and will fall back
** to xCurrentTime() if xCurrentTimeInt64() is unavailable.












*/
typedef struct sqlite3_vfs sqlite3_vfs;

struct sqlite3_vfs {
  int iVersion;            /* Structure version number (currently 2) */
  int szOsFile;            /* Size of subclassed sqlite3_file */
  int mxPathname;          /* Maximum file pathname length */
  sqlite3_vfs *pNext;      /* Next registered VFS */
  const char *zName;       /* Name of this virtual file system */
  void *pAppData;          /* Pointer to application-specific data */
  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
................................................................................
  /*
  ** The methods above are in version 1 of the sqlite_vfs object
  ** definition.  Those that follow are added in version 2 or later
  */
  int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  /*
  ** The methods above are in versions 1 and 2 of the sqlite_vfs object.







  ** New fields may be appended in figure versions.  The iVersion
  ** value will increment whenever this happens. 
  */
};

/*
** CAPI3REF: Flags for the xAccess VFS method
................................................................................

/*
** CAPI3REF: Configure database connections
**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).  The
** sqlite3_db_config() interface should only be used immediately after
** the database connection is created using [sqlite3_open()],
** [sqlite3_open16()], or [sqlite3_open_v2()].  
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** configuration verb - an integer code that indicates what

** aspect of the [database connection] is being configured.
** The only choice for this value is [SQLITE_DBCONFIG_LOOKASIDE].
** New verbs are likely to be added in future releases of SQLite.
** Additional arguments depend on the verb.

**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);

/*
................................................................................
** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
** allocation statistics are disabled by default.
** </dd>
**
** <dt>SQLITE_CONFIG_SCRATCH</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** scratch memory.  There are three arguments:  A pointer an 8-byte
** aligned memory buffer from which the scrach allocations will be
** drawn, the size of each scratch allocation (sz),
** and the maximum number of scratch allocations (N).  The sz
** argument must be a multiple of 16.
** The first argument must be a pointer to an 8-byte aligned buffer
** of at least sz*N bytes of memory.
** ^SQLite will use no more than two scratch buffers per thread.  So
** N should be set to twice the expected maximum number of threads.
................................................................................
** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.</dd>


**
** <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
................................................................................
** is invoked.
**
** <dl>
** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
** <dd> ^This option takes three additional arguments that determine the 
** [lookaside memory allocator] configuration for the [database connection].
** ^The first argument (the third parameter to [sqlite3_db_config()] is a
** pointer to an memory buffer to use for lookaside memory.
** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
** may be NULL in which case SQLite will allocate the
** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
** size of each lookaside buffer slot.  ^The third argument is the number of
** slots.  The size of the buffer in the first argument must be greater than
** or equal to the product of the second and third arguments.  The buffer
** must be aligned to an 8-byte boundary.  ^If the second argument to
................................................................................
** connection is not currently using lookaside memory, or in other words
** when the "current value" returned by
** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
** Any attempt to change the lookaside memory configuration when lookaside
** memory is in use leaves the configuration unchanged and returns 
** [SQLITE_BUSY].)^</dd>
**




















** </dl>
*/
#define SQLITE_DBCONFIG_LOOKASIDE    1001  /* void* int int */




/*
** CAPI3REF: Enable Or Disable Extended Result Codes
**
** ^The sqlite3_extended_result_codes() routine enables or disables the
** [extended result codes] feature of SQLite. ^The extended result
................................................................................
** method.
*/
SQLITE_API void sqlite3_randomness(int N, void *P);

/*
** CAPI3REF: Compile-Time Authorization Callbacks
**
** ^This routine registers a authorizer callback with a particular
** [database connection], supplied in the first argument.
** ^The authorizer callback is invoked as SQL statements are being compiled
** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
** points during the compilation process, as logic is being created
** to perform various actions, the authorizer callback is invoked to
** see if those actions are allowed.  ^The authorizer callback should
................................................................................
** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
*/
SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Determine If An SQL Statement Writes The Database
**
** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if 
** and only if the [prepared statement] X makes no direct changes to
** the content of the database file.
**
** Note that [application-defined SQL functions] or
** [virtual tables] might change the database indirectly as a side effect.  
** ^(For example, if an application defines a function "eval()" that 
** calls [sqlite3_exec()], then the following SQL statement would
................................................................................
** An sqlite3_value object may be either "protected" or "unprotected".
** Some interfaces require a protected sqlite3_value.  Other interfaces
** will accept either a protected or an unprotected sqlite3_value.
** Every interface that accepts sqlite3_value arguments specifies
** whether or not it requires a protected sqlite3_value.
**
** The terms "protected" and "unprotected" refer to whether or not
** a mutex is held.  A internal mutex is held for a protected
** sqlite3_value object but no mutex is held for an unprotected
** sqlite3_value object.  If SQLite is compiled to be single-threaded
** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
** or if SQLite is run in one of reduced mutex modes 
** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
** then there is no distinction between protected and unprotected
** sqlite3_value objects and they can be used interchangeably.  However,
................................................................................
** interface returns a pointer to a zero-terminated UTF-8 string
** and sqlite3_column_name16() returns a pointer to a zero-terminated
** UTF-16 string.  ^The first parameter is the [prepared statement]
** that implements the [SELECT] statement. ^The second parameter is the
** column number.  ^The leftmost column is number 0.
**
** ^The returned string pointer is valid until either the [prepared statement]
** is destroyed by [sqlite3_finalize()] or until the next call to


** sqlite3_column_name() or sqlite3_column_name16() on the same column.
**
** ^If sqlite3_malloc() fails during the processing of either routine
** (for example during a conversion from UTF-8 to UTF-16) then a
** NULL pointer is returned.
**
** ^The name of a result column is the value of the "AS" clause for
................................................................................
** table column that is the origin of a particular result column in
** [SELECT] statement.
** ^The name of the database or table or column can be returned as
** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
** the database name, the _table_ routines return the table name, and
** the origin_ routines return the column name.
** ^The returned string is valid until the [prepared statement] is destroyed


** using [sqlite3_finalize()] or until the same information is requested
** again in a different encoding.
**
** ^The names returned are the original un-aliased names of the
** database, table, and column.
**
** ^The first argument to these interfaces is a [prepared statement].
** ^These functions return information about the Nth result column returned by
................................................................................
** KEYWORDS: {application-defined SQL function}
** KEYWORDS: {application-defined SQL functions}
**
** ^These functions (collectively known as "function creation routines")
** are used to add SQL functions or aggregates or to redefine the behavior
** of existing SQL functions or aggregates.  The only differences between
** these routines are the text encoding expected for
** the the second parameter (the name of the function being created)
** and the presence or absence of a destructor callback for
** the application data pointer.
**
** ^The first parameter is the [database connection] to which the SQL
** function is to be added.  ^If an application uses more than one database
** connection then application-defined SQL functions must be added
** to each database connection separately.
................................................................................
**
** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
** pointers to C-language functions that implement the SQL function or
** aggregate. ^A scalar SQL function requires an implementation of the xFunc
** callback only; NULL pointers must be passed as the xStep and xFinal
** parameters. ^An aggregate SQL function requires an implementation of xStep
** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
** SQL function or aggregate, pass NULL poiners for all three function
** callbacks.
**
** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
** then it is destructor for the application data pointer. 
** The destructor is invoked when the function is deleted, either by being
** overloaded or when the database connection closes.)^
** ^The destructor is also invoked if the call to
................................................................................
** ^The eTextRep argument determines the encoding of strings passed
** to the collating function callback, xCallback.
** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
** force strings to be UTF16 with native byte order.
** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
** on an even byte address.
**
** ^The fourth argument, pArg, is a application data pointer that is passed
** through as the first argument to the collating function callback.
**
** ^The fifth argument, xCallback, is a pointer to the collating function.
** ^Multiple collating functions can be registered using the same name but
** with different eTextRep parameters and SQLite will use whichever
** function requires the least amount of data transformation.
** ^If the xCallback argument is NULL then the collating function is
................................................................................
** that collation is no longer usable.
**
** ^The collating function callback is invoked with a copy of the pArg 
** application data pointer and with two strings in the encoding specified
** by the eTextRep argument.  The collating function must return an
** integer that is negative, zero, or positive
** if the first string is less than, equal to, or greater than the second,
** respectively.  A collating function must alway return the same answer
** given the same inputs.  If two or more collating functions are registered
** to the same collation name (using different eTextRep values) then all
** must give an equivalent answer when invoked with equivalent strings.
** The collating function must obey the following properties for all
** strings A, B, and C:
**
** <ol>
................................................................................
** if one or more of following conditions are true:
**
** <ul>
** <li> The soft heap limit is set to zero.
** <li> Memory accounting is disabled using a combination of the
**      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
**      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
** <li> An alternative page cache implementation is specifed using
**      [sqlite3_config]([SQLITE_CONFIG_PCACHE],...).
** <li> The page cache allocates from its own memory pool supplied
**      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
**      from the heap.
** </ul>)^
**
** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
................................................................................
typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
typedef struct sqlite3_module sqlite3_module;

/*
** CAPI3REF: Virtual Table Object
** KEYWORDS: sqlite3_module {virtual table module}
**
** This structure, sometimes called a a "virtual table module", 
** defines the implementation of a [virtual tables].  
** This structure consists mostly of methods for the module.
**
** ^A virtual table module is created by filling in a persistent
** instance of this structure and passing a pointer to that instance
** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
** ^The registration remains valid until it is replaced by a different
................................................................................
**
** ^(If the row that a BLOB handle points to is modified by an
** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
** then the BLOB handle is marked as "expired".
** This is true if any column of the row is changed, even a column
** other than the one the BLOB handle is open on.)^
** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
** a expired BLOB handle fail with an return code of [SQLITE_ABORT].
** ^(Changes written into a BLOB prior to the BLOB expiring are not
** rolled back by the expiration of the BLOB.  Such changes will eventually
** commit if the transaction continues to completion.)^
**
** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
** the opened blob.  ^The size of a blob may not be changed by this
** interface.  Use the [UPDATE] SQL command to change the size of a
................................................................................
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
** <dd>This parameter returns the number of lookaside memory slots currently
** checked out.</dd>)^
**
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
** <dd>This parameter returns the number malloc attempts that were 
** satisfied using lookaside memory. Only the high-water value is meaningful;
** the current value is always zero.
** checked out.</dd>)^
**
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
** <dd>This parameter returns the number malloc attempts that might have
** been satisfied using lookaside memory but failed due to the amount of
** memory requested being larger than the lookaside slot size.
** Only the high-water value is meaningful;
** the current value is always zero.
** checked out.</dd>)^
**
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
** <dd>This parameter returns the number malloc attempts that might have
** been satisfied using lookaside memory but failed due to all lookaside
** memory already being in use.
** Only the high-water value is meaningful;
** the current value is always zero.
** checked out.</dd>)^
**
** ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
** <dd>This parameter returns the approximate number of of bytes of heap
** memory used by all pager caches associated with the database connection.)^
** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
**
** ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
................................................................................
** connection D.  ^If the database connection D is not in
** [WAL | write-ahead log mode] then this interface is a harmless no-op.
**
** ^The [wal_checkpoint pragma] can be used to invoke this interface
** from SQL.  ^The [sqlite3_wal_autocheckpoint()] interface and the
** [wal_autocheckpoint pragma] can be used to cause this interface to be
** run whenever the WAL reaches a certain size threshold.


*/
SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);




























































































/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
................................................................................

/*
** Forward declarations of structure
*/
typedef struct Btree Btree;
typedef struct BtCursor BtCursor;
typedef struct BtShared BtShared;
typedef struct BtreeMutexArray BtreeMutexArray;

/*
** This structure records all of the Btrees that need to hold
** a mutex before we enter sqlite3VdbeExec().  The Btrees are
** are placed in aBtree[] in order of aBtree[]->pBt.  That way,
** we can always lock and unlock them all quickly.
*/
struct BtreeMutexArray {
  int nMutex;
  Btree *aBtree[SQLITE_MAX_ATTACHED+1];
};


SQLITE_PRIVATE int sqlite3BtreeOpen(
  const char *zFilename,   /* Name of database file to open */
  sqlite3 *db,             /* Associated database connection */
  Btree **ppBtree,         /* Return open Btree* here */
  int flags,               /* Flags */
................................................................................
SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*);
SQLITE_PRIVATE int sqlite3BtreeCommit(Btree*);
SQLITE_PRIVATE int sqlite3BtreeRollback(Btree*);
SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree*, int*, int flags);
SQLITE_PRIVATE int sqlite3BtreeIsInTrans(Btree*);
SQLITE_PRIVATE int sqlite3BtreeIsInReadTrans(Btree*);
SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree*);
................................................................................

#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
SQLITE_PRIVATE void sqlite3BtreeCursorList(Btree*);
#endif

#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE   int sqlite3BtreeCheckpoint(Btree*);
#endif

/*
** If we are not using shared cache, then there is no need to
** use mutexes to access the BtShared structures.  So make the
** Enter and Leave procedures no-ops.
*/
................................................................................
SQLITE_PRIVATE   void sqlite3BtreeEnterAll(sqlite3*);
#else
# define sqlite3BtreeEnter(X) 
# define sqlite3BtreeEnterAll(X)
#endif

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE

SQLITE_PRIVATE   void sqlite3BtreeLeave(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeEnterCursor(BtCursor*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveCursor(BtCursor*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveAll(sqlite3*);
SQLITE_PRIVATE   void sqlite3BtreeMutexArrayEnter(BtreeMutexArray*);
SQLITE_PRIVATE   void sqlite3BtreeMutexArrayLeave(BtreeMutexArray*);
SQLITE_PRIVATE   void sqlite3BtreeMutexArrayInsert(BtreeMutexArray*, Btree*);
#ifndef NDEBUG
  /* These routines are used inside assert() statements only. */
SQLITE_PRIVATE   int sqlite3BtreeHoldsMutex(Btree*);
SQLITE_PRIVATE   int sqlite3BtreeHoldsAllMutexes(sqlite3*);

#endif
#else


# define sqlite3BtreeLeave(X)
# define sqlite3BtreeEnterCursor(X)
# define sqlite3BtreeLeaveCursor(X)
# define sqlite3BtreeLeaveAll(X)
# define sqlite3BtreeMutexArrayEnter(X)
# define sqlite3BtreeMutexArrayLeave(X)
# define sqlite3BtreeMutexArrayInsert(X,Y)

# define sqlite3BtreeHoldsMutex(X) 1
# define sqlite3BtreeHoldsAllMutexes(X) 1

#endif


#endif /* _BTREE_H_ */

/************** End of btree.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
................................................................................
#define P4_DYNAMIC  (-1)  /* Pointer to a string obtained from sqliteMalloc() */
#define P4_STATIC   (-2)  /* Pointer to a static string */
#define P4_COLLSEQ  (-4)  /* P4 is a pointer to a CollSeq structure */
#define P4_FUNCDEF  (-5)  /* P4 is a pointer to a FuncDef structure */
#define P4_KEYINFO  (-6)  /* P4 is a pointer to a KeyInfo structure */
#define P4_VDBEFUNC (-7)  /* P4 is a pointer to a VdbeFunc structure */
#define P4_MEM      (-8)  /* P4 is a pointer to a Mem*    structure */
#define P4_TRANSIENT (-9) /* P4 is a pointer to a transient string */
#define P4_VTAB     (-10) /* P4 is a pointer to an sqlite3_vtab structure */
#define P4_MPRINTF  (-11) /* P4 is a string obtained from sqlite3_mprintf() */
#define P4_REAL     (-12) /* P4 is a 64-bit floating point value */
#define P4_INT64    (-13) /* P4 is a 64-bit signed integer */
#define P4_INT32    (-14) /* P4 is a 32-bit signed integer */
#define P4_INTARRAY (-15) /* P4 is a vector of 32-bit integers */
#define P4_SUBPROGRAM  (-18) /* P4 is a pointer to a SubProgram structure */
................................................................................
SQLITE_PRIVATE int sqlite3PagerSync(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerCommitPhaseTwo(Pager*);
SQLITE_PRIVATE int sqlite3PagerRollback(Pager*);
SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager);

SQLITE_PRIVATE int sqlite3PagerCheckpoint(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerWalSupported(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
SQLITE_PRIVATE int sqlite3PagerCloseWal(Pager *pPager);

/* Functions used to query pager state and configuration. */
SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager*);
................................................................................
  u8 inTrans;          /* 0: not writable.  1: Transaction.  2: Checkpoint */
  u8 safety_level;     /* How aggressive at syncing data to disk */
  Schema *pSchema;     /* Pointer to database schema (possibly shared) */
};

/*
** An instance of the following structure stores a database schema.














*/
struct Schema {
  int schema_cookie;   /* Database schema version number for this file */

  Hash tblHash;        /* All tables indexed by name */
  Hash idxHash;        /* All (named) indices indexed by name */
  Hash trigHash;       /* All triggers indexed by name */
  Hash fkeyHash;       /* All foreign keys by referenced table name */
  Table *pSeqTab;      /* The sqlite_sequence table used by AUTOINCREMENT */
  u8 file_format;      /* Schema format version for this file */
  u8 enc;              /* Text encoding used by this database */
................................................................................
#define SQLITE_RecoveryMode   0x00800000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x01000000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x02000000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x04000000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x08000000  /* Enable automatic indexes */
#define SQLITE_PreferBuiltin  0x10000000  /* Preference to built-in funcs */
#define SQLITE_LoadExtension  0x20000000  /* Enable load_extension */


/*
** Bits of the sqlite3.flags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface.
** These must be the low-order bits of the flags field.
*/
#define SQLITE_QueryFlattener 0x01        /* Disable query flattening */
................................................................................
** schema. This is because each database connection requires its own unique
** instance of the sqlite3_vtab* handle used to access the virtual table 
** implementation. sqlite3_vtab* handles can not be shared between 
** database connections, even when the rest of the in-memory database 
** schema is shared, as the implementation often stores the database
** connection handle passed to it via the xConnect() or xCreate() method
** during initialization internally. This database connection handle may
** then used by the virtual table implementation to access real tables 
** within the database. So that they appear as part of the callers 
** transaction, these accesses need to be made via the same database 
** connection as that used to execute SQL operations on the virtual table.
**
** All VTable objects that correspond to a single table in a shared
** database schema are initially stored in a linked-list pointed to by
** the Table.pVTable member variable of the corresponding Table object.
................................................................................
  int nColumn;     /* Number of columns in the table used by this index */
  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
  Table *pTable;   /* The SQL table being indexed */
  int tnum;        /* Page containing root of this index in database file */
  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */

  char *zColAff;   /* String defining the affinity of each column */
  Index *pNext;    /* The next index associated with the same table */
  Schema *pSchema; /* Schema containing this index */
  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
  char **azColl;   /* Array of collation sequence names for index */
  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */
};
................................................................................
*/
struct Expr {
  u8 op;                 /* Operation performed by this node */
  char affinity;         /* The affinity of the column or 0 if not a column */
  u16 flags;             /* Various flags.  EP_* See below */
  union {
    char *zToken;          /* Token value. Zero terminated and dequoted */
    int iValue;            /* Integer value if EP_IntValue */
  } u;

  /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction. 
  *********************************************************************/

................................................................................
  Trigger *pTrigger;      /* Trigger this program was coded from */
  int orconf;             /* Default ON CONFLICT policy */
  SubProgram *pProgram;   /* Program implementing pTrigger/orconf */
  u32 aColmask[2];        /* Masks of old.*, new.* columns accessed */
  TriggerPrg *pNext;      /* Next entry in Parse.pTriggerPrg list */
};










/*
** An SQL parser context.  A copy of this structure is passed through
** the parser and down into all the parser action routine in order to
** carry around information that is global to the entire parse.
**
** The structure is divided into two parts.  When the parser and code
** generate call themselves recursively, the first part of the structure
................................................................................
    int iTable;           /* Table cursor number */
    int iColumn;          /* Table column number */
    u8 tempReg;           /* iReg is a temp register that needs to be freed */
    int iLevel;           /* Nesting level */
    int iReg;             /* Reg with value of this column. 0 means none. */
    int lru;              /* Least recently used entry has the smallest value */
  } aColCache[SQLITE_N_COLCACHE];  /* One for each column cache entry */
  u32 writeMask;       /* Start a write transaction on these databases */
  u32 cookieMask;      /* Bitmask of schema verified databases */
  u8 isMultiWrite;     /* True if statement may affect/insert multiple rows */
  u8 mayAbort;         /* True if statement may throw an ABORT exception */
  int cookieGoto;      /* Address of OP_Goto to cookie verifier subroutine */
  int cookieValue[SQLITE_MAX_ATTACHED+2];  /* Values of cookies to verify */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
................................................................................
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);
SQLITE_PRIVATE void sqlite3PrngSaveState(void);
SQLITE_PRIVATE void sqlite3PrngRestoreState(void);
SQLITE_PRIVATE void sqlite3PrngResetState(void);
SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*);
SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);

SQLITE_PRIVATE void sqlite3BeginTransaction(Parse*, int);
SQLITE_PRIVATE void sqlite3CommitTransaction(Parse*);
SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse*);
SQLITE_PRIVATE void sqlite3Savepoint(Parse*, int, Token*);
SQLITE_PRIVATE void sqlite3CloseSavepoints(sqlite3 *);
SQLITE_PRIVATE int sqlite3ExprIsConstant(Expr*);
SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr*);
................................................................................
SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
SQLITE_PRIVATE Expr *sqlite3ExprSetColl(Expr*, CollSeq*);
SQLITE_PRIVATE Expr *sqlite3ExprSetCollByToken(Parse *pParse, Expr*, Token*);
SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *, CollSeq *);
SQLITE_PRIVATE int sqlite3CheckObjectName(Parse *, const char *);
SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *, int);





SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value*, u8);
SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value*, u8);
SQLITE_PRIVATE void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8, 
                        void(*)(void*));
SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value*);
SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *);
................................................................................
SQLITE_PRIVATE const Token sqlite3IntTokens[];
SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config;
SQLITE_PRIVATE SQLITE_WSD FuncDefHash sqlite3GlobalFunctions;
#ifndef SQLITE_OMIT_WSD
SQLITE_PRIVATE int sqlite3PendingByte;
#endif
#endif
SQLITE_PRIVATE void sqlite3RootPageMoved(Db*, int, int);
SQLITE_PRIVATE void sqlite3Reindex(Parse*, Token*, Token*);
SQLITE_PRIVATE void sqlite3AlterFunctions(void);
SQLITE_PRIVATE void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *, int *);
SQLITE_PRIVATE void sqlite3NestedParse(Parse*, const char*, ...);
SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3*);
SQLITE_PRIVATE int sqlite3CodeSubselect(Parse *, Expr *, int, int);
................................................................................
SQLITE_PRIVATE int sqlite3FindDbName(sqlite3 *, const char *);
SQLITE_PRIVATE int sqlite3AnalysisLoad(sqlite3*,int iDB);
SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3*,Index*);
SQLITE_PRIVATE void sqlite3DefaultRowEst(Index*);
SQLITE_PRIVATE void sqlite3RegisterLikeFunctions(sqlite3*, int);
SQLITE_PRIVATE int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);
SQLITE_PRIVATE void sqlite3MinimumFileFormat(Parse*, int, int);
SQLITE_PRIVATE void sqlite3SchemaFree(void *);
SQLITE_PRIVATE Schema *sqlite3SchemaGet(sqlite3 *, Btree *);
SQLITE_PRIVATE int sqlite3SchemaToIndex(sqlite3 *db, Schema *);
SQLITE_PRIVATE KeyInfo *sqlite3IndexKeyinfo(Parse *, Index *);
SQLITE_PRIVATE int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *, 
  void (*)(sqlite3_context*,int,sqlite3_value **),
  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
  FuncDestructor *pDestructor
................................................................................
SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);
SQLITE_PRIVATE VTable *sqlite3GetVTable(sqlite3*, Table*);
SQLITE_PRIVATE const char *sqlite3JournalModename(int);
SQLITE_PRIVATE int sqlite3Checkpoint(sqlite3*, int);
SQLITE_PRIVATE int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);

/* Declarations for functions in fkey.c. All of these are replaced by
** no-op macros if OMIT_FOREIGN_KEY is defined. In this case no foreign
** key functionality is available. If OMIT_TRIGGER is defined but
** OMIT_FOREIGN_KEY is not, only some of the functions are no-oped. In
** this case foreign keys are parsed, but no other functionality is 
................................................................................
  u8 runOnlyOnce;         /* Automatically expire on reset */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */

  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
  int aCounter[3];        /* Counters used by sqlite3_stmt_status() */
  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
#ifndef SQLITE_OMIT_TRACE
  i64 startTime;          /* Time when query started - used for profiling */
#endif
  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
  char *zSql;             /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */
................................................................................
SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem);









#ifdef SQLITE_DEBUG
SQLITE_PRIVATE void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*);
#endif

#ifndef SQLITE_OMIT_FOREIGN_KEY
SQLITE_PRIVATE int sqlite3VdbeCheckFk(Vdbe *, int);
#else
# define sqlite3VdbeCheckFk(p,i) 0
#endif

#ifndef SQLITE_OMIT_SHARED_CACHE
SQLITE_PRIVATE void sqlite3VdbeMutexArrayEnter(Vdbe *p);
#else
# define sqlite3VdbeMutexArrayEnter(p)
#endif

SQLITE_PRIVATE int sqlite3VdbeMemTranslate(Mem*, u8);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   void sqlite3VdbePrintSql(Vdbe*);
SQLITE_PRIVATE   void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);
#endif
SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem);

................................................................................
    ** to store the schema for all databases (main, temp, and any ATTACHed
    ** databases.  *pHighwater is set to zero.
    */
    case SQLITE_DBSTATUS_SCHEMA_USED: {
      int i;                      /* Used to iterate through schemas */
      int nByte = 0;              /* Used to accumulate return value */


      db->pnBytesFreed = &nByte;
      for(i=0; i<db->nDb; i++){
        Schema *pSchema = db->aDb[i].pSchema;
        if( ALWAYS(pSchema!=0) ){
          HashElem *p;

          nByte += sqlite3GlobalConfig.m.xRoundup(sizeof(HashElem)) * (
................................................................................
          }
          for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
            sqlite3DeleteTable(db, (Table *)sqliteHashData(p));
          }
        }
      }
      db->pnBytesFreed = 0;


      *pHighwater = 0;
      *pCurrent = nByte;
      break;
    }

    /*
................................................................................

  /*
  ** Space for tracking which blocks are checked out and the size
  ** of each block.  One byte per block.
  */
  u8 *aCtrl;

} mem5 = { 0 };

/*
** Access the static variable through a macro for SQLITE_OMIT_WSD
*/
#define mem5 GLOBAL(struct Mem5Global, mem5)

/*
................................................................................
**             memsys5Log(4) -> 2
**             memsys5Log(5) -> 3
**             memsys5Log(8) -> 3
**             memsys5Log(9) -> 4
*/
static int memsys5Log(int iValue){
  int iLog;
  for(iLog=0; (1<<iLog)<iValue; iLog++);
  return iLog;
}

/*
** Initialize the memory allocator.
**
** This routine is not threadsafe.  The caller must be holding a mutex
................................................................................
  */
  assert( (sizeof(Mem5Link)&(sizeof(Mem5Link)-1))==0 );

  nByte = sqlite3GlobalConfig.nHeap;
  zByte = (u8*)sqlite3GlobalConfig.pHeap;
  assert( zByte!=0 );  /* sqlite3_config() does not allow otherwise */


  nMinLog = memsys5Log(sqlite3GlobalConfig.mnReq);
  mem5.szAtom = (1<<nMinLog);
  while( (int)sizeof(Mem5Link)>mem5.szAtom ){
    mem5.szAtom = mem5.szAtom << 1;
  }

  mem5.nBlock = (nByte / (mem5.szAtom+sizeof(u8)));
................................................................................
/*
** The mutex object
** Each recursive mutex is an instance of the following structure.
*/
struct sqlite3_mutex {
  HMTX mutex;       /* Mutex controlling the lock */
  int  id;          /* Mutex type */
  int  nRef;        /* Number of references */
  TID  owner;       /* Thread holding this mutex */

};




#define OS2_MUTEX_INITIALIZER   0,0,0,0


/*
** Initialize and deinitialize the mutex subsystem.
*/
static int os2MutexInit(void){ return SQLITE_OK; }
static int os2MutexEnd(void){ return SQLITE_OK; }

................................................................................
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated. 
** SQLite will unwind its stack and return an error.  The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST               0
** <li>  SQLITE_MUTEX_RECURSIVE          1
** <li>  SQLITE_MUTEX_STATIC_MASTER      2
** <li>  SQLITE_MUTEX_STATIC_MEM         3

** <li>  SQLITE_MUTEX_STATIC_PRNG        4


** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to.  But SQLite will only request a recursive mutex in
** cases where it really needs one.  If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex.  Three static mutexes are
** used by the current version of SQLite.  Future versions of SQLite
** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
................................................................................
          p = NULL;
        }
      }
      break;
    }
    default: {
      static volatile int isInit = 0;
      static sqlite3_mutex staticMutexes[] = {
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
        { OS2_MUTEX_INITIALIZER, },
      };
      if ( !isInit ){
        APIRET rc;
        PTIB ptib;
        PPIB ppib;
        HMTX mutex;
        char name[32];
................................................................................


/*
** This routine deallocates a previously allocated mutex.
** SQLite is careful to deallocate every mutex that it allocates.
*/
static void os2MutexFree(sqlite3_mutex *p){
  if( p==0 ) return;




  assert( p->nRef==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );

  DosCloseMutexSem( p->mutex );
  sqlite3_free( p );
}

#ifdef SQLITE_DEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
................................................................................
** intended for use inside assert() statements.
*/
static int os2MutexHeld(sqlite3_mutex *p){
  TID tid;
  PID pid;
  ULONG ulCount;
  PTIB ptib;
  if( p!=0 ) {
    DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);

  } else {
    DosGetInfoBlocks(&ptib, NULL);
    tid = ptib->tib_ptib2->tib2_ultid;
  }
  return p==0 || (p->nRef!=0 && p->owner==tid);
}
static int os2MutexNotheld(sqlite3_mutex *p){
  TID tid;
  PID pid;
  ULONG ulCount;
  PTIB ptib;
  if( p!= 0 ) {
    DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);

  } else {
    DosGetInfoBlocks(&ptib, NULL);
    tid = ptib->tib_ptib2->tib2_ultid;
  }
  return p==0 || p->nRef==0 || p->owner!=tid;





}
#endif

/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
................................................................................
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void os2MutexEnter(sqlite3_mutex *p){
  TID tid;
  PID holder1;
  ULONG holder2;
  if( p==0 ) return;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
  DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);
  DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
  p->owner = tid;
  p->nRef++;



}
static int os2MutexTry(sqlite3_mutex *p){
  int rc;
  TID tid;
  PID holder1;
  ULONG holder2;
  if( p==0 ) return SQLITE_OK;
  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
  if( DosRequestMutexSem(p->mutex, SEM_IMMEDIATE_RETURN) == NO_ERROR) {
    DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
    p->owner = tid;
    p->nRef++;
    rc = SQLITE_OK;
  } else {
    rc = SQLITE_BUSY;


  }

  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
static void os2MutexLeave(sqlite3_mutex *p){
  TID tid;
  PID holder1;
  ULONG holder2;
  if( p==0 ) return;
  assert( p->nRef>0 );
  DosQueryMutexSem(p->mutex, &holder1, &tid, &holder2);
  assert( p->owner==tid );
  p->nRef--;
  assert( p->nRef==0 || p->id==SQLITE_MUTEX_RECURSIVE );
  DosReleaseMutexSem(p->mutex);



}

SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
  static const sqlite3_mutex_methods sMutex = {
    os2MutexInit,
    os2MutexEnd,
    os2MutexAlloc,
................................................................................
    os2MutexFree,
    os2MutexEnter,
    os2MutexTry,
    os2MutexLeave,
#ifdef SQLITE_DEBUG
    os2MutexHeld,
    os2MutexNotheld



#endif
  };

  return &sMutex;
}
#endif /* SQLITE_MUTEX_OS2 */

................................................................................
    rc = SQLITE_OK;
  }
#else
  UNUSED_PARAMETER(p);
#endif
#ifdef SQLITE_DEBUG
  if( rc==SQLITE_OK && p->trace ){
    printf("enter mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }
#endif
  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
................................................................................
      /* Release memory from the SQLITE_CONFIG_SCRATCH allocation */
      ScratchFreeslot *pSlot;
      pSlot = (ScratchFreeslot*)p;
      sqlite3_mutex_enter(mem0.mutex);
      pSlot->pNext = mem0.pScratchFree;
      mem0.pScratchFree = pSlot;
      mem0.nScratchFree++;
      assert( mem0.nScratchFree<=sqlite3GlobalConfig.nScratch );
      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, -1);
      sqlite3_mutex_leave(mem0.mutex);
    }else{
      /* Release memory back to the heap */
      assert( sqlite3MemdebugHasType(p, MEMTYPE_SCRATCH) );
      assert( sqlite3MemdebugNoType(p, ~MEMTYPE_SCRATCH) );
      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
................................................................................
            v = va_arg(ap,i64);
          }else if( flag_long ){
            v = va_arg(ap,long int);
          }else{
            v = va_arg(ap,int);
          }
          if( v<0 ){



            longvalue = -v;

            prefix = '-';
          }else{
            longvalue = v;
            if( flag_plussign )        prefix = '+';
            else if( flag_blanksign )  prefix = ' ';
            else                       prefix = 0;
          }
................................................................................
        || (c&0xFFFFF800)==0xD800                          \
        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
  }
SQLITE_PRIVATE int sqlite3Utf8Read(
  const unsigned char *zIn,       /* First byte of UTF-8 character */
  const unsigned char **pzNext    /* Write first byte past UTF-8 char here */
){
  int c;

  /* Same as READ_UTF8() above but without the zTerm parameter.
  ** For this routine, we assume the UTF8 string is always zero-terminated.
  */
  c = *(zIn++);
  if( c>=0xc0 ){
    c = sqlite3Utf8Trans1[c-0xc0];
................................................................................
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
/*
** Translate UTF-8 to UTF-8.
**
** This has the effect of making sure that the string is well-formed
** UTF-8.  Miscoded characters are removed.
**
** The translation is done in-place (since it is impossible for the
** correct UTF-8 encoding to be longer than a malformed encoding).
*/
SQLITE_PRIVATE int sqlite3Utf8To8(unsigned char *zIn){
  unsigned char *zOut = zIn;
  unsigned char *zStart = zIn;
  u32 c;

  while( zIn[0] ){
    c = sqlite3Utf8Read(zIn, (const u8**)&zIn);
    if( c!=0xfffd ){
      WRITE_UTF8(zOut, c);
    }
  }
  *zOut = 0;
  return (int)(zOut - zStart);
................................................................................
#endif

/*
** Routine needed to support the testcase() macro.
*/
#ifdef SQLITE_COVERAGE_TEST
SQLITE_PRIVATE void sqlite3Coverage(int x){
  static int dummy = 0;
  dummy += x;
}
#endif

#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** Return true if the floating point value is Not a Number (NaN).
**
................................................................................
    testcase( c==(+1) );
  }
  return c;
}


/*
** Convert zNum to a 64-bit signed integer and write
** the value of the integer into *pNum.
** If zNum is exactly 9223372036854665808, return 2.
** This is a special case as the context will determine
** if it is too big (used as a negative).
** If zNum is not an integer or is an integer that 
** is too large to be expressed with 64 bits,
** then return 1.  Otherwise return 0.



**
** length is the number of bytes in the string (bytes, not characters).
** The string is not necessarily zero-terminated.  The encoding is
** given by enc.
*/
SQLITE_PRIVATE int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
  int incr = (enc==SQLITE_UTF8?1:2);
  i64 v = 0;
  int neg = 0; /* assume positive */
  int i;
  int c = 0;
  const char *zStart;
  const char *zEnd = zNum + length;
  if( enc==SQLITE_UTF16BE ) zNum++;
  while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
  if( zNum>=zEnd ) goto do_atoi_calc;
  if( *zNum=='-' ){
    neg = 1;
    zNum+=incr;
  }else if( *zNum=='+' ){
    zNum+=incr;
  }
do_atoi_calc:

  zStart = zNum;
  while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
  for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
    v = v*10 + c - '0';
  }



  *pNum = neg ? -v : v;



  testcase( i==18 );
  testcase( i==19 );
  testcase( i==20 );
  if( (c!=0 && &zNum[i]<zEnd) || (i==0 && zStart==zNum) || i>19*incr ){
    /* zNum is empty or contains non-numeric text or is longer
    ** than 19 digits (thus guaranteeing that it is too large) */
    return 1;
  }else if( i<19*incr ){
    /* Less than 19 digits, so we know that it fits in 64 bits */

    return 0;
  }else{
    /* 19-digit numbers must be no larger than 9223372036854775807 if positive
    ** or 9223372036854775808 if negative.  Note that 9223372036854665808
    ** is 2^63. Return 1 if to large */
    c=compare2pow63(zNum, incr);

    if( c==0 && neg==0 ) return 2; /* too big, exactly 9223372036854665808 */

    return c<neg ? 0 : 1;










  }
}

/*
** If zNum represents an integer that will fit in 32-bits, then set
** *pValue to that integer and return true.  Otherwise return false.
**
................................................................................
    testcase( sqlite3GlobalConfig.xLog!=0 );
    logBadConnection("invalid");
    return 0;
  }else{
    return 1;
  }
}





































































/************** End of util.c ************************************************/
/************** Begin file hash.c ********************************************/
/*
** 2001 September 22
**
** The author disclaims copyright to this source code.  In place of
................................................................................
#endif

#endif /* !defined(_OS_COMMON_H_) */

/************** End of os_common.h *******************************************/
/************** Continuing where we left off in os_os2.c *********************/






/*
** The os2File structure is subclass of sqlite3_file specific for the OS/2
** protability layer.
*/
typedef struct os2File os2File;
struct os2File {
  const sqlite3_io_methods *pMethod;  /* Always the first entry */
  HFILE h;                  /* Handle for accessing the file */
  char* pathToDel;          /* Name of file to delete on close, NULL if not */
  unsigned char locktype;   /* Type of lock currently held on this file */



};

#define LOCK_TIMEOUT 10L /* the default locking timeout */









/*****************************************************************************
** The next group of routines implement the I/O methods specified
** by the sqlite3_io_methods object.
******************************************************************************/

/*
** Close a file.
*/
static int os2Close( sqlite3_file *id ){
  APIRET rc = NO_ERROR;
  os2File *pFile;
  if( id && (pFile = (os2File*)id) != 0 ){
    OSTRACE(( "CLOSE %d\n", pFile->h ));
    rc = DosClose( pFile->h );
    pFile->locktype = NO_LOCK;
    if( pFile->pathToDel != NULL ){
      rc = DosForceDelete( (PSZ)pFile->pathToDel );
      free( pFile->pathToDel );
      pFile->pathToDel = NULL;
    }
    id = 0;
    OpenCounter( -1 );
  }




  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
................................................................................
  return ( rc != NO_ERROR || amt > (int)wrote ) ? SQLITE_FULL : SQLITE_OK;
}

/*
** Truncate an open file to a specified size
*/
static int os2Truncate( sqlite3_file *id, i64 nByte ){
  APIRET rc = NO_ERROR;
  os2File *pFile = (os2File*)id;

  OSTRACE(( "TRUNCATE %d %lld\n", pFile->h, nByte ));
  SimulateIOError( return SQLITE_IOERR_TRUNCATE );










  rc = DosSetFileSize( pFile->h, nByte );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR_TRUNCATE;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
................................................................................
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((os2File*)id)->locktype;
      OSTRACE(( "FCNTL_LOCKSTATE %d lock=%d\n",
                ((os2File*)id)->h, ((os2File*)id)->locktype ));
      return SQLITE_OK;
    }














  }
  return SQLITE_NOTFOUND;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
................................................................................
**
** SQLite code assumes this function cannot fail. It also assumes that
** if two files are created in the same file-system directory (i.e.
** a database and its journal file) that the sector size will be the
** same for both.
*/
static int os2SectorSize(sqlite3_file *id){

  return SQLITE_DEFAULT_SECTOR_SIZE;
}

/*
** Return a vector of device characteristics.
*/
static int os2DeviceCharacteristics(sqlite3_file *id){
  return 0;

}


/*
** Character set conversion objects used by conversion routines.
*/
static UconvObject ucUtf8 = NULL; /* convert between UTF-8 and UCS-2 */
................................................................................
    return out; /* if conversion fails, return the empty string */

  /* determine string for the conversion of UTF-8 which is CP1208 */
  UniStrFromUcs( ucUtf8, out, tempPath, CCHMAXPATH );

  return out;
}




/*








































































































































































































































































































































































































































































































































































































































































** This vector defines all the methods that can operate on an
** sqlite3_file for os2.
*/
static const sqlite3_io_methods os2IoMethod = {


  1,                        /* iVersion */
  os2Close,
  os2Read,
  os2Write,

  os2Truncate,
  os2Sync,

  os2FileSize,
  os2Lock,

  os2Unlock,
  os2CheckReservedLock,
  os2FileControl,
  os2SectorSize,
  os2DeviceCharacteristics




};


/***************************************************************************
** Here ends the I/O methods that form the sqlite3_io_methods object.
**
** The next block of code implements the VFS methods.
****************************************************************************/

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at pVfs->mxPathname characters.
*/
static int getTempname(int nBuf, char *zBuf ){
  static const unsigned char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  char zTempPathBuf[3];
  PSZ zTempPath = (PSZ)&zTempPathBuf;








  if( sqlite3_temp_directory ){
    zTempPath = sqlite3_temp_directory;
  }else{

    if( DosScanEnv( (PSZ)"TEMP", &zTempPath ) ){
      if( DosScanEnv( (PSZ)"TMP", &zTempPath ) ){
        if( DosScanEnv( (PSZ)"TMPDIR", &zTempPath ) ){
           ULONG ulDriveNum = 0, ulDriveMap = 0;



           DosQueryCurrentDisk( &ulDriveNum, &ulDriveMap );
           sprintf( (char*)zTempPath, "%c:", (char)( 'A' + ulDriveNum - 1 ) );




        }
      }
    }
  }
  /* Strip off a trailing slashes or backslashes, otherwise we would get *
   * multiple (back)slashes which causes DosOpen() to fail.              *
   * Trailing spaces are not allowed, either.                            */
  j = sqlite3Strlen30(zTempPath);
  while( j > 0 && ( zTempPath[j-1] == '\\' || zTempPath[j-1] == '/'
                    || zTempPath[j-1] == ' ' ) ){
    j--;
  }
  zTempPath[j] = '\0';
  if( !sqlite3_temp_directory ){

    char *zTempPathUTF = convertCpPathToUtf8( zTempPath );
    sqlite3_snprintf( nBuf-30, zBuf,
                      "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPathUTF );
    free( zTempPathUTF );
  }else{
    sqlite3_snprintf( nBuf-30, zBuf,
                      "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPath );
  }
  j = sqlite3Strlen30( zBuf );
  sqlite3_randomness( 20, &zBuf[j] );
  for( i = 0; i < 20; i++, j++ ){
    zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
  }
  zBuf[j] = 0;

  OSTRACE(( "TEMP FILENAME: %s\n", zBuf ));
  return SQLITE_OK;
}


/*
** Turn a relative pathname into a full pathname.  Write the full
................................................................................
  const char *zRelative,      /* Possibly relative input path */
  int nFull,                  /* Size of output buffer in bytes */
  char *zFull                 /* Output buffer */
){
  char *zRelativeCp = convertUtf8PathToCp( zRelative );
  char zFullCp[CCHMAXPATH] = "\0";
  char *zFullUTF;
  APIRET rc = DosQueryPathInfo( zRelativeCp, FIL_QUERYFULLNAME, zFullCp,
                                CCHMAXPATH );
  free( zRelativeCp );
  zFullUTF = convertCpPathToUtf8( zFullCp );
  sqlite3_snprintf( nFull, zFull, zFullUTF );
  free( zFullUTF );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
}


/*
** Open a file.
*/
static int os2Open(
  sqlite3_vfs *pVfs,            /* Not used */
  const char *zName,            /* Name of the file */
  sqlite3_file *id,             /* Write the SQLite file handle here */
  int flags,                    /* Open mode flags */
  int *pOutFlags                /* Status return flags */
){
  HFILE h;
  ULONG ulFileAttribute = FILE_NORMAL;
  ULONG ulOpenFlags = 0;
  ULONG ulOpenMode = 0;


  os2File *pFile = (os2File*)id;
  APIRET rc = NO_ERROR;
  ULONG ulAction;
  char *zNameCp;
  char zTmpname[CCHMAXPATH+1];    /* Buffer to hold name of temp file */















































  /* If the second argument to this function is NULL, generate a 
  ** temporary file name to use 
  */
  if( !zName ){

    int rc = getTempname(CCHMAXPATH+1, zTmpname);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    zName = zTmpname;
  }


  memset( pFile, 0, sizeof(*pFile) );

  OSTRACE(( "OPEN want %d\n", flags ));

  if( flags & SQLITE_OPEN_READWRITE ){

    ulOpenMode |= OPEN_ACCESS_READWRITE;
    OSTRACE(( "OPEN read/write\n" ));
  }else{
    ulOpenMode |= OPEN_ACCESS_READONLY;
    OSTRACE(( "OPEN read only\n" ));
  }

  if( flags & SQLITE_OPEN_CREATE ){
    ulOpenFlags |= OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW;
    OSTRACE(( "OPEN open new/create\n" ));
  }else{
    ulOpenFlags |= OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_FAIL_IF_NEW;
    OSTRACE(( "OPEN open existing\n" ));







  }








  if( flags & SQLITE_OPEN_MAIN_DB ){
    ulOpenMode |= OPEN_SHARE_DENYNONE;
    OSTRACE(( "OPEN share read/write\n" ));
  }else{
    ulOpenMode |= OPEN_SHARE_DENYWRITE;
    OSTRACE(( "OPEN share read only\n" ));
  }

  if( flags & SQLITE_OPEN_DELETEONCLOSE ){
    char pathUtf8[CCHMAXPATH];
#ifdef NDEBUG /* when debugging we want to make sure it is deleted */
    ulFileAttribute = FILE_HIDDEN;
#endif
    os2FullPathname( pVfs, zName, CCHMAXPATH, pathUtf8 );
    pFile->pathToDel = convertUtf8PathToCp( pathUtf8 );
    OSTRACE(( "OPEN hidden/delete on close file attributes\n" ));


  }else{
    pFile->pathToDel = NULL;
    OSTRACE(( "OPEN normal file attribute\n" ));


  }

  /* always open in random access mode for possibly better speed */
  ulOpenMode |= OPEN_FLAGS_RANDOM;
  ulOpenMode |= OPEN_FLAGS_FAIL_ON_ERROR;
  ulOpenMode |= OPEN_FLAGS_NOINHERIT;

  zNameCp = convertUtf8PathToCp( zName );
  rc = DosOpen( (PSZ)zNameCp,
                &h,
                &ulAction,
                0L,
                ulFileAttribute,

                ulOpenFlags,
                ulOpenMode,
                (PEAOP2)NULL );
  free( zNameCp );
  if( rc != NO_ERROR ){
    OSTRACE(( "OPEN Invalid handle rc=%d: zName=%s, ulAction=%#lx, ulAttr=%#lx, ulFlags=%#lx, ulMode=%#lx\n",
              rc, zName, ulAction, ulFileAttribute, ulOpenFlags, ulOpenMode ));
    if( pFile->pathToDel )
      free( pFile->pathToDel );
    pFile->pathToDel = NULL;
    if( flags & SQLITE_OPEN_READWRITE ){
      OSTRACE(( "OPEN %d Invalid handle\n",
                ((flags | SQLITE_OPEN_READONLY) & ~SQLITE_OPEN_READWRITE) ));
      return os2Open( pVfs, zName, id,
                      ((flags | SQLITE_OPEN_READONLY) & ~SQLITE_OPEN_READWRITE),
                      pOutFlags );
    }else{
      return SQLITE_CANTOPEN;
    }
  }

  if( pOutFlags ){
    *pOutFlags = flags & SQLITE_OPEN_READWRITE ? SQLITE_OPEN_READWRITE : SQLITE_OPEN_READONLY;
  }



  pFile->pMethod = &os2IoMethod;

  pFile->h = h;

  OpenCounter(+1);
  OSTRACE(( "OPEN %d pOutFlags=%d\n", pFile->h, pOutFlags ));
  return SQLITE_OK;
}

/*
** Delete the named file.
*/
static int os2Delete(
  sqlite3_vfs *pVfs,                     /* Not used on os2 */
  const char *zFilename,                 /* Name of file to delete */
  int syncDir                            /* Not used on os2 */
){
  APIRET rc = NO_ERROR;
  char *zFilenameCp = convertUtf8PathToCp( zFilename );
  SimulateIOError( return SQLITE_IOERR_DELETE );

  rc = DosDelete( (PSZ)zFilenameCp );
  free( zFilenameCp );
  OSTRACE(( "DELETE \"%s\"\n", zFilename ));


  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR_DELETE;
}

/*
** Check the existance and status of a file.
*/
static int os2Access(
  sqlite3_vfs *pVfs,        /* Not used on os2 */
  const char *zFilename,    /* Name of file to check */
  int flags,                /* Type of test to make on this file */
  int *pOut                 /* Write results here */
){

  FILESTATUS3 fsts3ConfigInfo;
  APIRET rc = NO_ERROR;
  char *zFilenameCp = convertUtf8PathToCp( zFilename );

  memset( &fsts3ConfigInfo, 0, sizeof(fsts3ConfigInfo) );



  rc = DosQueryPathInfo( (PSZ)zFilenameCp, FIL_STANDARD,
                         &fsts3ConfigInfo, sizeof(FILESTATUS3) );
  free( zFilenameCp );
  OSTRACE(( "ACCESS fsts3ConfigInfo.attrFile=%d flags=%d rc=%d\n",
            fsts3ConfigInfo.attrFile, flags, rc ));

  switch( flags ){
    case SQLITE_ACCESS_READ:






    case SQLITE_ACCESS_EXISTS:
      rc = (rc == NO_ERROR);
      OSTRACE(( "ACCESS %s access of read and exists  rc=%d\n", zFilename, rc));
      break;
    case SQLITE_ACCESS_READWRITE:
      rc = (rc == NO_ERROR) && ( (fsts3ConfigInfo.attrFile & FILE_READONLY) == 0 );
      OSTRACE(( "ACCESS %s access of read/write  rc=%d\n", zFilename, rc ));

      break;
    default:

      assert( !"Invalid flags argument" );
  }

  *pOut = rc;


  return SQLITE_OK;
}


#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
................................................................................
** within the shared library, and closing the shared library.
*/
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
static void *os2DlOpen(sqlite3_vfs *pVfs, const char *zFilename){
  UCHAR loadErr[256];
  HMODULE hmod;
  APIRET rc;
  char *zFilenameCp = convertUtf8PathToCp(zFilename);
  rc = DosLoadModule((PSZ)loadErr, sizeof(loadErr), zFilenameCp, &hmod);
  free(zFilenameCp);
  return rc != NO_ERROR ? 0 : (void*)hmod;
}
/*
** A no-op since the error code is returned on the DosLoadModule call.
** os2Dlopen returns zero if DosLoadModule is not successful.
*/
static void os2DlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
/* no-op */
}
static void *os2DlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol){
  PFN pfn;
  APIRET rc;
  rc = DosQueryProcAddr((HMODULE)pHandle, 0L, zSymbol, &pfn);
  if( rc != NO_ERROR ){
    /* if the symbol itself was not found, search again for the same
     * symbol with an extra underscore, that might be needed depending
     * on the calling convention */
    char _zSymbol[256] = "_";
    strncat(_zSymbol, zSymbol, 255);
    rc = DosQueryProcAddr((HMODULE)pHandle, 0L, _zSymbol, &pfn);
  }
  return rc != NO_ERROR ? 0 : (void*)pfn;
}
static void os2DlClose(sqlite3_vfs *pVfs, void *pHandle){
  DosFreeModule((HMODULE)pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define os2DlOpen 0
  #define os2DlError 0
................................................................................
*/
static int os2Randomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf ){
  int n = 0;
#if defined(SQLITE_TEST)
  n = nBuf;
  memset(zBuf, 0, nBuf);
#else
  int sizeofULong = sizeof(ULONG);
  if( (int)sizeof(DATETIME) <= nBuf - n ){

    DATETIME x;
    DosGetDateTime(&x);
    memcpy(&zBuf[n], &x, sizeof(x));
    n += sizeof(x);



  }


  if( sizeofULong <= nBuf - n ){
    PPIB ppib;
    DosGetInfoBlocks(NULL, &ppib);



    memcpy(&zBuf[n], &ppib->pib_ulpid, sizeofULong);
    n += sizeofULong;
  }


  if( sizeofULong <= nBuf - n ){
    PTIB ptib;
    DosGetInfoBlocks(&ptib, NULL);

    memcpy(&zBuf[n], &ptib->tib_ptib2->tib2_ultid, sizeofULong);
    n += sizeofULong;
  }

  /* if we still haven't filled the buffer yet the following will */
  /* grab everything once instead of making several calls for a single item */
  if( sizeofULong <= nBuf - n ){
    ULONG ulSysInfo[QSV_MAX];
    DosQuerySysInfo(1L, QSV_MAX, ulSysInfo, sizeofULong * QSV_MAX);


    memcpy(&zBuf[n], &ulSysInfo[QSV_MS_COUNT - 1], sizeofULong);
    n += sizeofULong;

    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TIMER_INTERVAL - 1], sizeofULong);

      n += sizeofULong;
    }
    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TIME_LOW - 1], sizeofULong);
      n += sizeofULong;
    }
    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TIME_HIGH - 1], sizeofULong);
      n += sizeofULong;
    }
    if( sizeofULong <= nBuf - n ){
      memcpy(&zBuf[n], &ulSysInfo[QSV_TOTAVAILMEM - 1], sizeofULong);
      n += sizeofULong;
    }
  }
#endif

  return n;
}

/*
** Sleep for a little while.  Return the amount of time slept.
................................................................................
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_current_time = 0;
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
int os2CurrentTime( sqlite3_vfs *pVfs, double *prNow ){
  double now;
  SHORT minute; /* needs to be able to cope with negative timezone offset */
  USHORT second, hour,
         day, month, year;
  DATETIME dt;
  DosGetDateTime( &dt );
  second = (USHORT)dt.seconds;
  minute = (SHORT)dt.minutes + dt.timezone;
  hour = (USHORT)dt.hours;
  day = (USHORT)dt.day;
  month = (USHORT)dt.month;
  year = (USHORT)dt.year;

  /* Calculations from http://www.astro.keele.ac.uk/~rno/Astronomy/hjd.html
     http://www.astro.keele.ac.uk/~rno/Astronomy/hjd-0.1.c */
  /* Calculate the Julian days */
  now = day - 32076 +



    1461*(year + 4800 + (month - 14)/12)/4 +
    367*(month - 2 - (month - 14)/12*12)/12 -
    3*((year + 4900 + (month - 14)/12)/100)/4;

  /* Add the fractional hours, mins and seconds */
  now += (hour + 12.0)/24.0;
  now += minute/1440.0;
  now += second/86400.0;

  *prNow = now;

#ifdef SQLITE_TEST
  if( sqlite3_current_time ){
    *prNow = sqlite3_current_time/86400.0 + 2440587.5;

  }
#endif


  return 0;
}














































static int os2GetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){

  return 0;
}

/*
** Initialize and deinitialize the operating system interface.
*/
SQLITE_API int sqlite3_os_init(void){
  static sqlite3_vfs os2Vfs = {
    1,                 /* iVersion */
    sizeof(os2File),   /* szOsFile */
    CCHMAXPATH,        /* mxPathname */
    0,                 /* pNext */
    "os2",             /* zName */
    0,                 /* pAppData */

    os2Open,           /* xOpen */
................................................................................
    os2DlError,        /* xDlError */
    os2DlSym,          /* xDlSym */
    os2DlClose,        /* xDlClose */
    os2Randomness,     /* xRandomness */
    os2Sleep,          /* xSleep */
    os2CurrentTime,    /* xCurrentTime */
    os2GetLastError,   /* xGetLastError */




  };
  sqlite3_vfs_register(&os2Vfs, 1);
  initUconvObjects();

  return SQLITE_OK;
}
SQLITE_API int sqlite3_os_end(void){
  freeUconvObjects();
  return SQLITE_OK;
}

................................................................................
typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  unixInodeInfo *pInode;              /* Info about locks on this inode */
  int h;                              /* The file descriptor */
  int dirfd;                          /* File descriptor for the directory */
  unsigned char eFileLock;            /* The type of lock held on this fd */

  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  int fileFlags;                      /* Miscellanous flags */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                      /* The flags specified at open() */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
................................................................................
  ** it is larger than the struct CrashFile defined in test6.c.
  */
  char aPadding[32];
#endif
};

/*
** The following macros define bits in unixFile.fileFlags
*/
#define SQLITE_WHOLE_FILE_LOCKING  0x0001   /* Use whole-file locking */


/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_unix.c ***************/
/************** Begin file os_common.h ***************************************/
/*
................................................................................
#ifndef O_NOFOLLOW
# define O_NOFOLLOW 0
#endif
#ifndef O_BINARY
# define O_BINARY 0
#endif

/*




































** The DJGPP compiler environment looks mostly like Unix, but it
** lacks the fcntl() system call.  So redefine fcntl() to be something
** that always succeeds.  This means that locking does not occur under
** DJGPP.  But it is DOS - what did you expect?
*/
#ifdef __DJGPP__
# define fcntl(A,B,C) 0





#endif

























































/*
** The threadid macro resolves to the thread-id or to 0.  Used for
** testing and debugging only.




*/













#if SQLITE_THREADSAFE
#define threadid pthread_self()





#else
#define threadid 0
#endif


































































/*
** Helper functions to obtain and relinquish the global mutex. The
** global mutex is used to protect the unixInodeInfo and
** vxworksFileId objects used by this file, all of which may be 
** shared by multiple threads.
**
................................................................................
  int s;
  int savedErrno;
  if( op==F_GETLK ){
    zOpName = "GETLK";
  }else if( op==F_SETLK ){
    zOpName = "SETLK";
  }else{
    s = fcntl(fd, op, p);
    sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s);
    return s;
  }
  if( p->l_type==F_RDLCK ){
    zType = "RDLCK";
  }else if( p->l_type==F_WRLCK ){
    zType = "WRLCK";
  }else if( p->l_type==F_UNLCK ){
    zType = "UNLCK";
  }else{
    assert( 0 );
  }
  assert( p->l_whence==SEEK_SET );
  s = fcntl(fd, op, p);
  savedErrno = errno;
  sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n",
     threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len,
     (int)p->l_pid, s);
  if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){
    struct flock l2;
    l2 = *p;
    fcntl(fd, F_GETLK, &l2);
    if( l2.l_type==F_RDLCK ){
      zType = "RDLCK";
    }else if( l2.l_type==F_WRLCK ){
      zType = "WRLCK";
    }else if( l2.l_type==F_UNLCK ){
      zType = "UNLCK";
    }else{
................................................................................
    }
    sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n",
       zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid);
  }
  errno = savedErrno;
  return s;
}

#define fcntl lockTrace
#endif /* SQLITE_LOCK_TRACE */










/*
** This routine translates a standard POSIX errno code into something
** useful to the clients of the sqlite3 functions.  Specifically, it is
** intended to translate a variety of "try again" errors into SQLITE_BUSY
** and a variety of "please close the file descriptor NOW" errors into 
** SQLITE_IOERR
** 
** Errors during initialization of locks, or file system support for locks,
** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately.
*/
static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) {
  switch (posixError) {












  case 0: 
    return SQLITE_OK;

    
  case EAGAIN:
  case ETIMEDOUT:
  case EBUSY:
  case EINTR:
  case ENOLCK:  
    /* random NFS retry error, unless during file system support 
     * introspection, in which it actually means what it says */
................................................................................
	(sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){
      return SQLITE_BUSY;
    }
    /* else fall through */
  case EPERM: 
    return SQLITE_PERM;
    






  case EDEADLK:
    return SQLITE_IOERR_BLOCKED;

    
#if EOPNOTSUPP!=ENOTSUP
  case EOPNOTSUPP: 
    /* something went terribly awry, unless during file system support 
     * introspection, in which it actually means what it says */
#endif
#ifdef ENOTSUP
................................................................................
** A single inode can have multiple file descriptors, so each unixFile
** structure contains a pointer to an instance of this object and this
** object keeps a count of the number of unixFile pointing to it.
*/
struct unixInodeInfo {
  struct unixFileId fileId;       /* The lookup key */
  int nShared;                    /* Number of SHARED locks held */
  int eFileLock;                  /* One of SHARED_LOCK, RESERVED_LOCK etc. */

  int nRef;                       /* Number of pointers to this structure */
  unixShmNode *pShmNode;          /* Shared memory associated with this inode */
  int nLock;                      /* Number of outstanding file locks */
  UnixUnusedFd *pUnused;          /* Unused file descriptors to close */
  unixInodeInfo *pNext;           /* List of all unixInodeInfo objects */
  unixInodeInfo *pPrev;           /*    .... doubly linked */
#if defined(SQLITE_ENABLE_LOCKING_STYLE)
................................................................................

/*
** A lists of all unixInodeInfo objects.
*/
static unixInodeInfo *inodeList = 0;

/*
** Close all file descriptors accumuated in the unixInodeInfo->pUnused list.
** If all such file descriptors are closed without error, the list is
** cleared and SQLITE_OK returned.
**
** Otherwise, if an error occurs, then successfully closed file descriptor
** entries are removed from the list, and SQLITE_IOERR_CLOSE returned. 














































































** not deleted and SQLITE_IOERR_CLOSE returned.






*/ 
static int closePendingFds(unixFile *pFile){
  int rc = SQLITE_OK;
  unixInodeInfo *pInode = pFile->pInode;
  UnixUnusedFd *pError = 0;
  UnixUnusedFd *p;
  UnixUnusedFd *pNext;
  for(p=pInode->pUnused; p; p=pNext){
    pNext = p->pNext;
    if( close(p->fd) ){
      pFile->lastErrno = errno;
      rc = SQLITE_IOERR_CLOSE;
      p->pNext = pError;
      pError = p;
    }else{
      sqlite3_free(p);
    }
  }
  pInode->pUnused = pError;
  return rc;
}

/*
** Release a unixInodeInfo structure previously allocated by findInodeInfo().
**
** The mutex entered using the unixEnterMutex() function must be held
** when this function is called.
*/
static void releaseInodeInfo(unixFile *pFile){
  unixInodeInfo *pInode = pFile->pInode;
  assert( unixMutexHeld() );
  if( pInode ){
    pInode->nRef--;
    if( pInode->nRef==0 ){
      assert( pInode->pShmNode==0 );
      closePendingFds(pFile);
      if( pInode->pPrev ){
        assert( pInode->pPrev->pNext==pInode );
        pInode->pPrev->pNext = pInode->pNext;
................................................................................

  assert( unixMutexHeld() );

  /* Get low-level information about the file that we can used to
  ** create a unique name for the file.
  */
  fd = pFile->h;
  rc = fstat(fd, &statbuf);
  if( rc!=0 ){
    pFile->lastErrno = errno;
#ifdef EOVERFLOW
    if( pFile->lastErrno==EOVERFLOW ) return SQLITE_NOLFS;
#endif
    return SQLITE_IOERR;
  }
................................................................................
  ** prior to accessing the inode number.  The one byte written is
  ** an ASCII 'S' character which also happens to be the first byte
  ** in the header of every SQLite database.  In this way, if there
  ** is a race condition such that another thread has already populated
  ** the first page of the database, no damage is done.
  */
  if( statbuf.st_size==0 && (pFile->fsFlags & SQLITE_FSFLAGS_IS_MSDOS)!=0 ){
    rc = write(fd, "S", 1);
    if( rc!=1 ){
      pFile->lastErrno = errno;
      return SQLITE_IOERR;
    }
    rc = fstat(fd, &statbuf);
    if( rc!=0 ){
      pFile->lastErrno = errno;
      return SQLITE_IOERR;
    }
  }
#endif

................................................................................
  if( pFile->pInode->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it.
  */
#ifndef __DJGPP__
  if( !reserved ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    if (-1 == fcntl(pFile->h, F_GETLK, &lock)) {
      int tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_CHECKRESERVEDLOCK);
      pFile->lastErrno = tErrno;
    } else if( lock.l_type!=F_UNLCK ){
      reserved = 1;
    }
  }
#endif
  
  unixLeaveMutex();
  OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));

  *pResOut = reserved;
  return rc;
}
















































/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
................................................................................
  ** locking a random byte from a range, concurrent SHARED locks may exist
  ** even if the locking primitive used is always a write-lock.
  */
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode = pFile->pInode;
  struct flock lock;
  int s = 0;
  int tErrno = 0;

  assert( pFile );
  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
      azFileLock(eFileLock), azFileLock(pFile->eFileLock),
      azFileLock(pInode->eFileLock), pInode->nShared , getpid()));

................................................................................
  lock.l_len = 1L;
  lock.l_whence = SEEK_SET;
  if( eFileLock==SHARED_LOCK 
      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
  ){
    lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){

        pFile->lastErrno = tErrno;
      }
      goto end_lock;
    }
  }


  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( eFileLock==SHARED_LOCK ){
    assert( pInode->nShared==0 );
    assert( pInode->eFileLock==0 );


    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    if( (s = fcntl(pFile->h, F_SETLK, &lock))==(-1) ){
      tErrno = errno;

    }

    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( fcntl(pFile->h, F_SETLK, &lock)!=0 ){
      if( s != -1 ){
        /* This could happen with a network mount */
        tErrno = errno; 
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); 
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
        goto end_lock;
      }
    }
    if( s==(-1) ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){

        pFile->lastErrno = tErrno;
      }

    }else{
      pFile->eFileLock = SHARED_LOCK;
      pInode->nLock++;
      pInode->nShared = 1;
    }
  }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
    /* We are trying for an exclusive lock but another thread in this
................................................................................
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    assert( 0!=pFile->eFileLock );
    lock.l_type = F_WRLCK;
    switch( eFileLock ){


      case RESERVED_LOCK:
        lock.l_start = RESERVED_BYTE;
        break;
      case EXCLUSIVE_LOCK:

        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        break;
      default:
        assert(0);
    }
    s = fcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){


      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){

        pFile->lastErrno = tErrno;
      }
    }
  }
  

#ifndef NDEBUG
................................................................................
** 
** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
** the byte range is divided into 2 parts and the first part is unlocked then
** set to a read lock, then the other part is simply unlocked.  This works 
** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to 
** remove the write lock on a region when a read lock is set.
*/
static int _posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode;
  struct flock lock;
  int rc = SQLITE_OK;
  int h;
  int tErrno;                      /* Error code from system call errors */

  assert( pFile );
  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
      pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
      getpid()));

  assert( eFileLock<=SHARED_LOCK );
................................................................................
    ** write lock until the rest is covered by a read lock:
    **  1:   [WWWWW]
    **  2:   [....W]
    **  3:   [RRRRW]
    **  4:   [RRRR.]
    */
    if( eFileLock==SHARED_LOCK ){






      if( handleNFSUnlock ){

        off_t divSize = SHARED_SIZE - 1;
        
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( fcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( fcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST+divSize;
        lock.l_len = SHARED_SIZE-divSize;
        if( fcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
      }else{


        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        if( fcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;





          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( fcntl(h, F_SETLK, &lock)!=(-1) ){
      pInode->eFileLock = SHARED_LOCK;
    }else{
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
      goto end_unlock;
    }
  }
  if( eFileLock==NO_LOCK ){
    /* Decrement the shared lock counter.  Release the lock using an
    ** OS call only when all threads in this same process have released
    ** the lock.
................................................................................
    if( pInode->nShared==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( fcntl(h, F_SETLK, &lock)!=(-1) ){
        pInode->eFileLock = NO_LOCK;
      }else{
        tErrno = errno;
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
        pInode->eFileLock = NO_LOCK;
        pFile->eFileLock = NO_LOCK;
      }
    }

    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */
    pInode->nLock--;
    assert( pInode->nLock>=0 );
    if( pInode->nLock==0 ){
      int rc2 = closePendingFds(pFile);
      if( rc==SQLITE_OK ){
        rc = rc2;
      }
    }
  }
	
end_unlock:
  unixLeaveMutex();
  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
  return rc;
................................................................................
** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int eFileLock){
  return _posixUnlock(id, eFileLock, 0);
}

/*
** This function performs the parts of the "close file" operation 
** common to all locking schemes. It closes the directory and file
** handles, if they are valid, and sets all fields of the unixFile
** structure to 0.
................................................................................
**
** It is *not* necessary to hold the mutex when this routine is called,
** even on VxWorks.  A mutex will be acquired on VxWorks by the
** vxworksReleaseFileId() routine.
*/
static int closeUnixFile(sqlite3_file *id){
  unixFile *pFile = (unixFile*)id;
  if( pFile ){
    if( pFile->dirfd>=0 ){
      int err = close(pFile->dirfd);
      if( err ){
        pFile->lastErrno = errno;
        return SQLITE_IOERR_DIR_CLOSE;
      }else{

        pFile->dirfd=-1;
      }
    }
    if( pFile->h>=0 ){

      int err = close(pFile->h);
      if( err ){
        pFile->lastErrno = errno;
        return SQLITE_IOERR_CLOSE;
      }
    }
#if OS_VXWORKS
    if( pFile->pId ){
      if( pFile->isDelete ){
        unlink(pFile->pId->zCanonicalName);
      }
      vxworksReleaseFileId(pFile->pId);
      pFile->pId = 0;
    }
#endif
    OSTRACE(("CLOSE   %-3d\n", pFile->h));
    OpenCounter(-1);
    sqlite3_free(pFile->pUnused);
    memset(pFile, 0, sizeof(unixFile));
  }
  return SQLITE_OK;
}

/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
  int rc = SQLITE_OK;
  if( id ){
    unixFile *pFile = (unixFile *)id;
    unixUnlock(id, NO_LOCK);
    unixEnterMutex();





    if( pFile->pInode && pFile->pInode->nLock ){
      /* If there are outstanding locks, do not actually close the file just
      ** yet because that would clear those locks.  Instead, add the file
      ** descriptor to pInode->pUnused list.  It will be automatically closed 
      ** when the last lock is cleared.
      */
      setPendingFd(pFile);
    }
    releaseInodeInfo(pFile);
    rc = closeUnixFile(id);
    unixLeaveMutex();
  }
  return rc;
}

/************** End of the posix advisory lock implementation *****************
******************************************************************************/

/******************************************************************************
................................................................................
  if( pFile->eFileLock>SHARED_LOCK ){
    /* Either this connection or some other connection in the same process
    ** holds a lock on the file.  No need to check further. */
    reserved = 1;
  }else{
    /* The lock is held if and only if the lockfile exists */
    const char *zLockFile = (const char*)pFile->lockingContext;
    reserved = access(zLockFile, 0)==0;
  }
  OSTRACE(("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, rc, reserved));
  *pResOut = reserved;
  return rc;
}

/*
................................................................................
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
#endif
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  fd = open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
  if( fd<0 ){
    /* failed to open/create the file, someone else may have stolen the lock */
    int tErrno = errno;
    if( EEXIST == tErrno ){
      rc = SQLITE_BUSY;
    } else {
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
    return rc;
  } 
  if( close(fd) ){
    pFile->lastErrno = errno;
    rc = SQLITE_IOERR_CLOSE;
  }
  
  /* got it, set the type and return ok */
  pFile->eFileLock = eFileLock;
  return rc;
}

/*
................................................................................
  
  /* To fully unlock the database, delete the lock file */
  assert( eFileLock==NO_LOCK );
  if( unlink(zLockFile) ){
    int rc = 0;
    int tErrno = errno;
    if( ENOENT != tErrno ){
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    }
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc; 
  }
  pFile->eFileLock = NO_LOCK;
................................................................................
** only a single process can be reading the database at a time.
**
** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off or if
** compiling for VXWORKS.
*/
#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS















/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){
................................................................................
  if( pFile->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    /* attempt to get the lock */
    int lrc = flock(pFile->h, LOCK_EX | LOCK_NB);
    if( !lrc ){
      /* got the lock, unlock it */
      lrc = flock(pFile->h, LOCK_UN);
      if ( lrc ) {
        int tErrno = errno;
        /* unlock failed with an error */
        lrc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); 
        if( IS_LOCK_ERROR(lrc) ){
          pFile->lastErrno = tErrno;
          rc = lrc;
        }
      }
    } else {
      int tErrno = errno;
................................................................................
  if (pFile->eFileLock > NO_LOCK) {
    pFile->eFileLock = eFileLock;
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  
  if (flock(pFile->h, LOCK_EX | LOCK_NB)) {
    int tErrno = errno;
    /* didn't get, must be busy */
    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
  } else {
................................................................................
  /* shared can just be set because we always have an exclusive */
  if (eFileLock==SHARED_LOCK) {
    pFile->eFileLock = eFileLock;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  int rc = flock(pFile->h, LOCK_UN);
  if (rc) {
    int r, tErrno = errno;
    r = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
    if( IS_LOCK_ERROR(r) ){
      pFile->lastErrno = tErrno;
    }
#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS
    if( (r & SQLITE_IOERR) == SQLITE_IOERR ){
      r = SQLITE_BUSY;
    }
#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */
    
    return r;
  } else {
    pFile->eFileLock = NO_LOCK;
    return SQLITE_OK;
  }
}

/*
** Close a file.
................................................................................
        pFile->eFileLock = NO_LOCK;
      }
    }
    if( rc==SQLITE_OK ){
      pInode->nLock--;
      assert( pInode->nLock>=0 );
      if( pInode->nLock==0 ){
        rc = closePendingFds(pFile);
      }
    }
  }
  
  unixLeaveMutex();
  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
  return rc;
................................................................................
 ** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
 ** must be either NO_LOCK or SHARED_LOCK.
 **
 ** If the locking level of the file descriptor is already at or below
 ** the requested locking level, this routine is a no-op.
 */
static int nfsUnlock(sqlite3_file *id, int eFileLock){
  return _posixUnlock(id, eFileLock, 1);
}

#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
/*
** The code above is the NFS lock implementation.  The code is specific
** to MacOSX and does not work on other unix platforms.  No alternative
** is available.  
................................................................................
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
  int got;
#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
  i64 newOffset;
#endif
  TIMER_START;
#if defined(USE_PREAD)
  got = pread(id->h, pBuf, cnt, offset);
  SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
  got = pread64(id->h, pBuf, cnt, offset);
  SimulateIOError( got = -1 );
#else
  newOffset = lseek(id->h, offset, SEEK_SET);
  SimulateIOError( newOffset-- );
  if( newOffset!=offset ){
    if( newOffset == -1 ){
      ((unixFile*)id)->lastErrno = errno;
    }else{
      ((unixFile*)id)->lastErrno = 0;			
    }
    return -1;
  }
  got = read(id->h, pBuf, cnt);
#endif
  TIMER_END;
  if( got<0 ){
    ((unixFile*)id)->lastErrno = errno;
  }
  OSTRACE(("READ    %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
  return got;
................................................................................
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
  int got;
#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
  i64 newOffset;
#endif
  TIMER_START;
#if defined(USE_PREAD)
  got = pwrite(id->h, pBuf, cnt, offset);
#elif defined(USE_PREAD64)
  got = pwrite64(id->h, pBuf, cnt, offset);
#else
  newOffset = lseek(id->h, offset, SEEK_SET);

  if( newOffset!=offset ){
    if( newOffset == -1 ){
      ((unixFile*)id)->lastErrno = errno;
    }else{
      ((unixFile*)id)->lastErrno = 0;			
    }
    return -1;
  }
  got = write(id->h, pBuf, cnt);
#endif
  TIMER_END;
  if( got<0 ){
    ((unixFile*)id)->lastErrno = errno;
  }

  OSTRACE(("WRITE   %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
................................................................................
  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
  rc = SQLITE_OK;
#elif HAVE_FULLFSYNC
  if( fullSync ){
    rc = fcntl(fd, F_FULLFSYNC, 0);
  }else{
    rc = 1;
  }
  /* If the FULLFSYNC failed, fall back to attempting an fsync().
  ** It shouldn't be possible for fullfsync to fail on the local 
  ** file system (on OSX), so failure indicates that FULLFSYNC
  ** isn't supported for this file system. So, attempt an fsync 
................................................................................

  assert( pFile );
  OSTRACE(("SYNC    %-3d\n", pFile->h));
  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
    pFile->lastErrno = errno;
    return SQLITE_IOERR_FSYNC;
  }
  if( pFile->dirfd>=0 ){
    int err;
    OSTRACE(("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
            HAVE_FULLFSYNC, isFullsync));
#ifndef SQLITE_DISABLE_DIRSYNC
    /* The directory sync is only attempted if full_fsync is
    ** turned off or unavailable.  If a full_fsync occurred above,
    ** then the directory sync is superfluous.
    */
................................................................................
       ** A failed directory sync is not a big deal.  So it seems
       ** better to ignore the error.  Ticket #1657
       */
       /* pFile->lastErrno = errno; */
       /* return SQLITE_IOERR; */
    }
#endif
    err = close(pFile->dirfd); /* Only need to sync once, so close the */
    if( err==0 ){              /* directory when we are done */
      pFile->dirfd = -1;
    }else{
      pFile->lastErrno = errno;
      rc = SQLITE_IOERR_DIR_CLOSE;
    }
  }
  return rc;
}

/*
** Truncate an open file to a specified size
*/
................................................................................
  ** actual file size after the operation may be larger than the requested
  ** size).
  */
  if( pFile->szChunk ){
    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
  }

  rc = ftruncate(pFile->h, (off_t)nByte);
  if( rc ){
    pFile->lastErrno = errno;
    return SQLITE_IOERR_TRUNCATE;
  }else{
#ifndef NDEBUG
    /* If we are doing a normal write to a database file (as opposed to
    ** doing a hot-journal rollback or a write to some file other than a
    ** normal database file) and we truncate the file to zero length,
    ** that effectively updates the change counter.  This might happen
    ** when restoring a database using the backup API from a zero-length
................................................................................
/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(sqlite3_file *id, i64 *pSize){
  int rc;
  struct stat buf;
  assert( id );
  rc = fstat(((unixFile*)id)->h, &buf);
  SimulateIOError( rc=1 );
  if( rc!=0 ){
    ((unixFile*)id)->lastErrno = errno;
    return SQLITE_IOERR_FSTAT;
  }
  *pSize = buf.st_size;

................................................................................
** SQLITE_FCNTL_SIZE_HINT operation is a no-op for Unix.
*/
static int fcntlSizeHint(unixFile *pFile, i64 nByte){
  if( pFile->szChunk ){
    i64 nSize;                    /* Required file size */
    struct stat buf;              /* Used to hold return values of fstat() */
   
    if( fstat(pFile->h, &buf) ) return SQLITE_IOERR_FSTAT;

    nSize = ((nByte+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk;
    if( nSize>(i64)buf.st_size ){

#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE





      if( posix_fallocate(pFile->h, buf.st_size, nSize-buf.st_size) ){

        return SQLITE_IOERR_WRITE;
      }
#else
      /* If the OS does not have posix_fallocate(), fake it. First use
      ** ftruncate() to set the file size, then write a single byte to
      ** the last byte in each block within the extended region. This
      ** is the same technique used by glibc to implement posix_fallocate()
      ** on systems that do not have a real fallocate() system call.
      */
      int nBlk = buf.st_blksize;  /* File-system block size */
      i64 iWrite;                 /* Next offset to write to */
      int nWrite;                 /* Return value from seekAndWrite() */

      if( ftruncate(pFile->h, nSize) ){
        pFile->lastErrno = errno;
        return SQLITE_IOERR_TRUNCATE;
      }
      iWrite = ((buf.st_size + 2*nBlk - 1)/nBlk)*nBlk-1;
      do {

        nWrite = seekAndWrite(pFile, iWrite, "", 1);
        iWrite += nBlk;
      } while( nWrite==1 && iWrite<nSize );
      if( nWrite!=1 ) return SQLITE_IOERR_WRITE;


#endif
    }
  }

  return SQLITE_OK;
}

................................................................................

  /* Shared locks never span more than one byte */
  assert( n==1 || lockType!=F_RDLCK );

  /* Locks are within range */
  assert( n>=1 && n<SQLITE_SHM_NLOCK );


  /* Initialize the locking parameters */
  memset(&f, 0, sizeof(f));
  f.l_type = lockType;
  f.l_whence = SEEK_SET;
  f.l_start = ofst;
  f.l_len = n;

  rc = fcntl(pShmNode->h, F_SETLK, &f);
  rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY;


  /* Update the global lock state and do debug tracing */
#ifdef SQLITE_DEBUG
  { u16 mask;
  OSTRACE(("SHM-LOCK "));
  mask = (1<<(ofst+n)) - (1<<ofst);
  if( rc==SQLITE_OK ){
................................................................................
  unixShmNode *p = pFd->pInode->pShmNode;
  assert( unixMutexHeld() );
  if( p && p->nRef==0 ){
    int i;
    assert( p->pInode==pFd->pInode );
    if( p->mutex ) sqlite3_mutex_free(p->mutex);
    for(i=0; i<p->nRegion; i++){

      munmap(p->apRegion[i], p->szRegion);


    }

    sqlite3_free(p->apRegion);
    if( p->h>=0 ) close(p->h);



    p->pInode->pShmNode = 0;
    sqlite3_free(p);
  }
}

/*
** Open a shared-memory area associated with open database file pDbFd.  
................................................................................
** same database file at the same time, database corruption will likely
** result. The SQLITE_SHM_DIRECTORY compile-time option is considered
** "unsupported" and may go away in a future SQLite release.
**
** When opening a new shared-memory file, if no other instances of that
** file are currently open, in this process or in other processes, then
** the file must be truncated to zero length or have its header cleared.






*/
static int unixOpenSharedMemory(unixFile *pDbFd){
  struct unixShm *p = 0;          /* The connection to be opened */
  struct unixShmNode *pShmNode;   /* The underlying mmapped file */
  int rc;                         /* Result code */
  unixInodeInfo *pInode;          /* The inode of fd */
  char *zShmFilename;             /* Name of the file used for SHM */
................................................................................
    struct stat sStat;                 /* fstat() info for database file */

    /* Call fstat() to figure out the permissions on the database file. If
    ** a new *-shm file is created, an attempt will be made to create it
    ** with the same permissions. The actual permissions the file is created
    ** with are subject to the current umask setting.
    */
    if( fstat(pDbFd->h, &sStat) ){
      rc = SQLITE_IOERR_FSTAT;
      goto shm_open_err;
    }

#ifdef SQLITE_SHM_DIRECTORY
    nShmFilename = sizeof(SQLITE_SHM_DIRECTORY) + 30;
#else
................................................................................
    pShmNode->pInode = pDbFd->pInode;
    pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
    if( pShmNode->mutex==0 ){
      rc = SQLITE_NOMEM;
      goto shm_open_err;
    }



    pShmNode->h = open(zShmFilename, O_RDWR|O_CREAT, (sStat.st_mode & 0777));
    if( pShmNode->h<0 ){
      rc = SQLITE_CANTOPEN_BKPT;
      goto shm_open_err;
    }

    /* Check to see if another process is holding the dead-man switch.
    ** If not, truncate the file to zero length. 
    */
    rc = SQLITE_OK;
    if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
      if( ftruncate(pShmNode->h, 0) ){
        rc = SQLITE_IOERR_SHMOPEN;
      }
    }
    if( rc==SQLITE_OK ){
      rc = unixShmSystemLock(pShmNode, F_RDLCK, UNIX_SHM_DMS, 1);
    }
    if( rc ) goto shm_open_err;

  }

  /* Make the new connection a child of the unixShmNode */
  p->pShmNode = pShmNode;
#ifdef SQLITE_DEBUG
  p->id = pShmNode->nextShmId++;
#endif
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }

  p = pDbFd->pShm;
  pShmNode = p->pShmNode;
  sqlite3_mutex_enter(pShmNode->mutex);
  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );




  if( pShmNode->nRegion<=iRegion ){
    char **apNew;                      /* New apRegion[] array */
    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
    struct stat sStat;                 /* Used by fstat() */

    pShmNode->szRegion = szRegion;


    /* The requested region is not mapped into this processes address space.
    ** Check to see if it has been allocated (i.e. if the wal-index file is
    ** large enough to contain the requested region).
    */
    if( fstat(pShmNode->h, &sStat) ){
      rc = SQLITE_IOERR_SHMSIZE;
      goto shmpage_out;
    }

    if( sStat.st_size<nByte ){
      /* The requested memory region does not exist. If bExtend is set to
      ** false, exit early. *pp will be set to NULL and SQLITE_OK returned.
      **
      ** Alternatively, if bExtend is true, use ftruncate() to allocate
      ** the requested memory region.
      */
      if( !bExtend ) goto shmpage_out;
      if( ftruncate(pShmNode->h, nByte) ){
        rc = SQLITE_IOERR_SHMSIZE;
        goto shmpage_out;
      }















    }

    /* Map the requested memory region into this processes address space. */
    apNew = (char **)sqlite3_realloc(
        pShmNode->apRegion, (iRegion+1)*sizeof(char *)
    );
    if( !apNew ){
      rc = SQLITE_IOERR_NOMEM;
      goto shmpage_out;
    }
    pShmNode->apRegion = apNew;
    while(pShmNode->nRegion<=iRegion){


      void *pMem = mmap(0, szRegion, PROT_READ|PROT_WRITE, 
          MAP_SHARED, pShmNode->h, pShmNode->nRegion*szRegion
      );
      if( pMem==MAP_FAILED ){
        rc = SQLITE_IOERR;
        goto shmpage_out;








      }
      pShmNode->apRegion[pShmNode->nRegion] = pMem;
      pShmNode->nRegion++;
    }
  }

shmpage_out:
................................................................................
  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
  assert( n>=1 );
  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );



  mask = (1<<(ofst+n)) - (1<<ofst);
  assert( n>1 || mask==(1<<ofst) );
  sqlite3_mutex_enter(pShmNode->mutex);
  if( flags & SQLITE_SHM_UNLOCK ){
    u16 allMask = 0; /* Mask of locks held by siblings */

................................................................................

  /* If pShmNode->nRef has reached 0, then close the underlying
  ** shared-memory file, too */
  unixEnterMutex();
  assert( pShmNode->nRef>0 );
  pShmNode->nRef--;
  if( pShmNode->nRef==0 ){
    if( deleteFlag ) unlink(pShmNode->zFilename);
    unixShmPurge(pDbFd);
  }
  unixLeaveMutex();

  return SQLITE_OK;
}

................................................................................
  ** Test byte-range lock using fcntl(). If the call succeeds, 
  ** assume that the file-system supports POSIX style locks. 
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( fcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
    if( strcmp(fsInfo.f_fstypename, "nfs")==0 ){
      return &nfsIoMethods;
    } else {
      return &posixIoMethods;
    }
  }else{
    return &dotlockIoMethods;
................................................................................
  /* Test if fcntl() is supported and use POSIX style locks.
  ** Otherwise fall back to the named semaphore method.
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( fcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
    return &posixIoMethods;
  }else{
    return &semIoMethods;
  }
}
static const sqlite3_io_methods 
  *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
................................................................................
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int dirfd,              /* Directory file descriptor */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete            /* Delete on close if true */

){
  const sqlite3_io_methods *pLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;

  assert( pNew->pInode==NULL );

................................................................................
#else
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->dirfd = dirfd;
  pNew->fileFlags = 0;
  pNew->zPath = zFilename;









#if OS_VXWORKS
  pNew->pId = vxworksFindFileId(zFilename);
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
................................................................................
      ** handle h - as it is guaranteed that no posix locks will be released
      ** by doing so.
      **
      ** If scenario (a) caused the error then things are not so safe. The
      ** implicit assumption here is that if fstat() fails, things are in
      ** such bad shape that dropping a lock or two doesn't matter much.
      */
      close(h);
      h = -1;
    }
    unixLeaveMutex();
  }

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
  else if( pLockingStyle == &afpIoMethods ){
................................................................................
      pCtx->dbPath = zFilename;
      pCtx->reserved = 0;
      srandomdev();
      unixEnterMutex();
      rc = findInodeInfo(pNew, &pNew->pInode);
      if( rc!=SQLITE_OK ){
        sqlite3_free(pNew->lockingContext);
        close(h);
        h = -1;
      }
      unixLeaveMutex();        
    }
  }
#endif

................................................................................
    unixLeaveMutex();
  }
#endif
  
  pNew->lastErrno = 0;
#if OS_VXWORKS
  if( rc!=SQLITE_OK ){
    if( h>=0 ) close(h);
    h = -1;
    unlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) close(dirfd); /* silent leak if fail, already in error */
    if( h>=0 ) close(h);
  }else{
    pNew->pMethod = pLockingStyle;
    OpenCounter(+1);
  }
  return rc;
}

................................................................................
  int fd = -1;
  char zDirname[MAX_PATHNAME+1];

  sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
  for(ii=(int)strlen(zDirname); ii>1 && zDirname[ii]!='/'; ii--);
  if( ii>0 ){
    zDirname[ii] = '\0';
    fd = open(zDirname, O_RDONLY|O_BINARY, 0);
    if( fd>=0 ){
#ifdef FD_CLOEXEC
      fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif
      OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
    }
  }
  *pFd = fd;
  return (fd>=0?SQLITE_OK:SQLITE_CANTOPEN_BKPT);
}

/*
** Return the name of a directory in which to put temporary files.
** If no suitable temporary file directory can be found, return NULL.
*/
static const char *unixTempFileDir(void){
................................................................................
  struct stat buf;
  const char *zDir = 0;

  azDirs[0] = sqlite3_temp_directory;
  if( !azDirs[1] ) azDirs[1] = getenv("TMPDIR");
  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); zDir=azDirs[i++]){
    if( zDir==0 ) continue;
    if( stat(zDir, &buf) ) continue;
    if( !S_ISDIR(buf.st_mode) ) continue;
    if( access(zDir, 07) ) continue;
    break;
  }
  return zDir;
}

/*
** Create a temporary file name in zBuf.  zBuf must be allocated
................................................................................
    sqlite3_snprintf(nBuf-17, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX, zDir);
    j = (int)strlen(zBuf);
    sqlite3_randomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
  }while( access(zBuf,0)==0 );
  return SQLITE_OK;
}

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
/*
** Routine to transform a unixFile into a proxy-locking unixFile.
** Implementation in the proxy-lock division, but used by unixOpen()
................................................................................
    mode_t openMode;              /* Permissions to create file with */
    rc = findCreateFileMode(zName, flags, &openMode);
    if( rc!=SQLITE_OK ){
      assert( !p->pUnused );
      assert( eType==SQLITE_OPEN_WAL || eType==SQLITE_OPEN_MAIN_JOURNAL );
      return rc;
    }
    fd = open(zName, openFlags, openMode);
    OSTRACE(("OPENX   %-3d %s 0%o\n", fd, zName, openFlags));
    if( fd<0 && errno!=EISDIR && isReadWrite && !isExclusive ){
      /* Failed to open the file for read/write access. Try read-only. */
      flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
      openFlags &= ~(O_RDWR|O_CREAT);
      flags |= SQLITE_OPEN_READONLY;
      openFlags |= O_RDONLY;

      fd = open(zName, openFlags, openMode);
    }
    if( fd<0 ){
      rc = SQLITE_CANTOPEN_BKPT;
      goto open_finished;
    }
  }
  assert( fd>=0 );
  if( pOutFlags ){
    *pOutFlags = flags;
  }
................................................................................
    rc = openDirectory(zPath, &dirfd);
    if( rc!=SQLITE_OK ){
      /* It is safe to close fd at this point, because it is guaranteed not
      ** to be open on a database file. If it were open on a database file,
      ** it would not be safe to close as this would release any locks held
      ** on the file by this process.  */
      assert( eType!=SQLITE_OPEN_MAIN_DB );
      close(fd);             /* silently leak if fail, already in error */
      goto open_finished;
    }
  }

#ifdef FD_CLOEXEC
  fcntl(fd, F_SETFD, fcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif

  noLock = eType!=SQLITE_OPEN_MAIN_DB;

  
#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
  struct statfs fsInfo;
  if( fstatfs(fd, &fsInfo) == -1 ){
    ((unixFile*)pFile)->lastErrno = errno;
    if( dirfd>=0 ) close(dirfd); /* silently leak if fail, in error */
    close(fd); /* silently leak if fail, in error */
    return SQLITE_IOERR_ACCESS;
  }
  if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) {
    ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
  }
#endif
  
................................................................................
        ** on that file that are currently holding advisory locks on it,
        ** then the call to close() will cancel those locks. In practice,
        ** we're assuming that statfs() doesn't fail very often. At least
        ** not while other file descriptors opened by the same process on
        ** the same file are working.  */
        p->lastErrno = errno;
        if( dirfd>=0 ){
          close(dirfd); /* silently leak if fail, in error */
        }
        close(fd); /* silently leak if fail, in error */
        rc = SQLITE_IOERR_ACCESS;
        goto open_finished;
      }
      useProxy = !(fsInfo.f_flags&MNT_LOCAL);
    }
    if( useProxy ){
      rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock, isDelete);

      if( rc==SQLITE_OK ){
        rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
        if( rc!=SQLITE_OK ){
          /* Use unixClose to clean up the resources added in fillInUnixFile 
          ** and clear all the structure's references.  Specifically, 
          ** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op 
          */
................................................................................
        }
      }
      goto open_finished;
    }
  }
#endif
  
  rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock, isDelete);

open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
  }
  return rc;
}

................................................................................
  const char *zPath,        /* Name of file to be deleted */
  int dirSync               /* If true, fsync() directory after deleting file */
){
  int rc = SQLITE_OK;
  UNUSED_PARAMETER(NotUsed);
  SimulateIOError(return SQLITE_IOERR_DELETE);
  if( unlink(zPath)==(-1) && errno!=ENOENT ){
    return SQLITE_IOERR_DELETE;
  }
#ifndef SQLITE_DISABLE_DIRSYNC
  if( dirSync ){
    int fd;
    rc = openDirectory(zPath, &fd);
    if( rc==SQLITE_OK ){
#if OS_VXWORKS
      if( fsync(fd)==-1 )
#else
      if( fsync(fd) )
#endif
      {
        rc = SQLITE_IOERR_DIR_FSYNC;
      }
      if( close(fd)&&!rc ){
        rc = SQLITE_IOERR_DIR_CLOSE;
      }
    }
  }
#endif
  return rc;
}

/*
................................................................................
    case SQLITE_ACCESS_READ:
      amode = R_OK;
      break;

    default:
      assert(!"Invalid flags argument");
  }
  *pResOut = (access(zPath, amode)==0);
  if( flags==SQLITE_ACCESS_EXISTS && *pResOut ){
    struct stat buf;
    if( 0==stat(zPath, &buf) && buf.st_size==0 ){
      *pResOut = 0;
    }
  }
  return SQLITE_OK;
................................................................................
  UNUSED_PARAMETER(pVfs);

  zOut[nOut-1] = '\0';
  if( zPath[0]=='/' ){
    sqlite3_snprintf(nOut, zOut, "%s", zPath);
  }else{
    int nCwd;
    if( getcwd(zOut, nOut-1)==0 ){
      return SQLITE_CANTOPEN_BKPT;
    }
    nCwd = (int)strlen(zOut);
    sqlite3_snprintf(nOut-nCwd, &zOut[nCwd], "/%s", zPath);
  }
  return SQLITE_OK;
}

................................................................................
  ** that we always use the same random number sequence.  This makes the
  ** tests repeatable.
  */
  memset(zBuf, 0, nBuf);
#if !defined(SQLITE_TEST)
  {
    int pid, fd;
    fd = open("/dev/urandom", O_RDONLY);
    if( fd<0 ){
      time_t t;
      time(&t);
      memcpy(zBuf, &t, sizeof(t));
      pid = getpid();
      memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
      assert( sizeof(t)+sizeof(pid)<=(size_t)nBuf );
      nBuf = sizeof(t) + sizeof(pid);
    }else{
      nBuf = read(fd, zBuf, nBuf);
      close(fd);
    }
  }
#endif
  return nBuf;
}


................................................................................
  }else{
    pUnused = sqlite3_malloc(sizeof(*pUnused));
    if( !pUnused ){
      return SQLITE_NOMEM;
    }
  }
  if( fd<0 ){
    fd = open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
    terrno = errno;
    if( fd<0 && errno==ENOENT && islockfile ){
      if( proxyCreateLockPath(path) == SQLITE_OK ){
        fd = open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
      }
    }
  }
  if( fd<0 ){
    openFlags = O_RDONLY;
    fd = open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
    terrno = errno;
  }
  if( fd<0 ){
    if( islockfile ){
      return SQLITE_BUSY;
    }
    switch (terrno) {
................................................................................
  pNew = (unixFile *)sqlite3_malloc(sizeof(*pNew));
  if( pNew==NULL ){
    rc = SQLITE_NOMEM;
    goto end_create_proxy;
  }
  memset(pNew, 0, sizeof(unixFile));
  pNew->openFlags = openFlags;

  dummyVfs.pAppData = (void*)&autolockIoFinder;

  pUnused->fd = fd;
  pUnused->flags = openFlags;
  pNew->pUnused = pUnused;
  
  rc = fillInUnixFile(&dummyVfs, fd, dirfd, (sqlite3_file*)pNew, path, 0, 0);
  if( rc==SQLITE_OK ){
    *ppFile = pNew;
    return SQLITE_OK;
  }
end_create_proxy:    
  close(fd); /* silently leak fd if error, we're already in error */
  sqlite3_free(pNew);
  sqlite3_free(pUnused);
  return rc;
}

#ifdef SQLITE_TEST
/* simulate multiple hosts by creating unique hostid file paths */
................................................................................
  pathLen = strlcpy(tPath, cPath, MAXPATHLEN);
  if( pathLen>MAXPATHLEN || pathLen<6 || 
     (strlcpy(&tPath[pathLen-5], "break", 6) != 5) ){
    sqlite3_snprintf(sizeof(errmsg),errmsg,"path error (len %d)",(int)pathLen);
    goto end_breaklock;
  }
  /* read the conch content */
  readLen = pread(conchFile->h, buf, PROXY_MAXCONCHLEN, 0);
  if( readLen<PROXY_PATHINDEX ){
    sqlite3_snprintf(sizeof(errmsg),errmsg,"read error (len %d)",(int)readLen);
    goto end_breaklock;
  }
  /* write it out to the temporary break file */

  fd = open(tPath, (O_RDWR|O_CREAT|O_EXCL), SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( fd<0 ){
    sqlite3_snprintf(sizeof(errmsg), errmsg, "create failed (%d)", errno);
    goto end_breaklock;
  }
  if( pwrite(fd, buf, readLen, 0) != (ssize_t)readLen ){
    sqlite3_snprintf(sizeof(errmsg), errmsg, "write failed (%d)", errno);
    goto end_breaklock;
  }
  if( rename(tPath, cPath) ){
    sqlite3_snprintf(sizeof(errmsg), errmsg, "rename failed (%d)", errno);
    goto end_breaklock;
  }
  rc = 0;
  fprintf(stderr, "broke stale lock on %s\n", cPath);
  close(conchFile->h);
  conchFile->h = fd;
  conchFile->openFlags = O_RDWR | O_CREAT;

end_breaklock:
  if( rc ){
    if( fd>=0 ){
      unlink(tPath);
      close(fd);
    }
    fprintf(stderr, "failed to break stale lock on %s, %s\n", cPath, errmsg);
  }
  return rc;
}

/* Take the requested lock on the conch file and break a stale lock if the 
................................................................................
      /* If the lock failed (busy):
       * 1st try: get the mod time of the conch, wait 0.5s and try again. 
       * 2nd try: fail if the mod time changed or host id is different, wait 
       *           10 sec and try again
       * 3rd try: break the lock unless the mod time has changed.
       */
      struct stat buf;
      if( fstat(conchFile->h, &buf) ){
        pFile->lastErrno = errno;
        return SQLITE_IOERR_LOCK;
      }
      
      if( nTries==1 ){
        conchModTime = buf.st_mtimespec;
        usleep(500000); /* wait 0.5 sec and try the lock again*/
................................................................................
      if( conchModTime.tv_sec != buf.st_mtimespec.tv_sec || 
         conchModTime.tv_nsec != buf.st_mtimespec.tv_nsec ){
        return SQLITE_BUSY;
      }
      
      if( nTries==2 ){  
        char tBuf[PROXY_MAXCONCHLEN];
        int len = pread(conchFile->h, tBuf, PROXY_MAXCONCHLEN, 0);
        if( len<0 ){
          pFile->lastErrno = errno;
          return SQLITE_IOERR_LOCK;
        }
        if( len>PROXY_PATHINDEX && tBuf[0]==(char)PROXY_CONCHVERSION){
          /* don't break the lock if the host id doesn't match */
          if( 0!=memcmp(&tBuf[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN) ){
................................................................................
        memcpy(&writeBuffer[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN);
        if( pCtx->lockProxyPath!=NULL ){
          strlcpy(&writeBuffer[PROXY_PATHINDEX], pCtx->lockProxyPath, MAXPATHLEN);
        }else{
          strlcpy(&writeBuffer[PROXY_PATHINDEX], tempLockPath, MAXPATHLEN);
        }
        writeSize = PROXY_PATHINDEX + strlen(&writeBuffer[PROXY_PATHINDEX]);
        ftruncate(conchFile->h, writeSize);
        rc = unixWrite((sqlite3_file *)conchFile, writeBuffer, writeSize, 0);
        fsync(conchFile->h);
        /* If we created a new conch file (not just updated the contents of a 
         ** valid conch file), try to match the permissions of the database 
         */
        if( rc==SQLITE_OK && createConch ){
          struct stat buf;
          int err = fstat(pFile->h, &buf);
          if( err==0 ){
            mode_t cmode = buf.st_mode&(S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP |
                                        S_IROTH|S_IWOTH);
            /* try to match the database file R/W permissions, ignore failure */
#ifndef SQLITE_PROXY_DEBUG
            fchmod(conchFile->h, cmode);
#else

            if( fchmod(conchFile->h, cmode)!=0 ){


              int code = errno;
              fprintf(stderr, "fchmod %o FAILED with %d %s\n",
                      cmode, code, strerror(code));
            } else {
              fprintf(stderr, "fchmod %o SUCCEDED\n",cmode);
            }
          }else{
................................................................................
      }
      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK);
      
    end_takeconch:
      OSTRACE(("TRANSPROXY: CLOSE  %d\n", pFile->h));
      if( rc==SQLITE_OK && pFile->openFlags ){
        if( pFile->h>=0 ){
#ifdef STRICT_CLOSE_ERROR
          if( close(pFile->h) ){
            pFile->lastErrno = errno;
            return SQLITE_IOERR_CLOSE;
          }
#else
          close(pFile->h); /* silently leak fd if fail */
#endif
        }
        pFile->h = -1;
        int fd = open(pCtx->dbPath, pFile->openFlags,
                      SQLITE_DEFAULT_FILE_PERMISSIONS);
        OSTRACE(("TRANSPROXY: OPEN  %d\n", fd));
        if( fd>=0 ){
          pFile->h = fd;
        }else{
          rc=SQLITE_CANTOPEN_BKPT; /* SQLITE_BUSY? proxyTakeConch called
           during locking */
................................................................................
      ** Ugh, since O_RDONLY==0x0000 we test for !O_RDWR since unixOpen asserts
      ** that openFlags will have only one of O_RDONLY or O_RDWR.
      */
      struct statfs fsInfo;
      struct stat conchInfo;
      int goLockless = 0;

      if( stat(pCtx->conchFilePath, &conchInfo) == -1 ) {
        int err = errno;
        if( (err==ENOENT) && (statfs(dbPath, &fsInfo) != -1) ){
          goLockless = (fsInfo.f_flags&MNT_RDONLY) == MNT_RDONLY;
        }
      }
      if( goLockless ){
        pCtx->conchHeld = -1; /* read only FS/ lockless */
................................................................................
  ** Most finders simply return a pointer to a fixed sqlite3_io_methods
  ** object.  But the "autolockIoFinder" available on MacOSX does a little
  ** more than that; it looks at the filesystem type that hosts the 
  ** database file and tries to choose an locking method appropriate for
  ** that filesystem time.
  */
  #define UNIXVFS(VFSNAME, FINDER) {                        \
    2,                    /* iVersion */                    \
    sizeof(unixFile),     /* szOsFile */                    \
    MAX_PATHNAME,         /* mxPathname */                  \
    0,                    /* pNext */                       \
    VFSNAME,              /* zName */                       \
    (void*)&FINDER,       /* pAppData */                    \
    unixOpen,             /* xOpen */                       \
    unixDelete,           /* xDelete */                     \
................................................................................
    unixDlSym,            /* xDlSym */                      \
    unixDlClose,          /* xDlClose */                    \
    unixRandomness,       /* xRandomness */                 \
    unixSleep,            /* xSleep */                      \
    unixCurrentTime,      /* xCurrentTime */                \
    unixGetLastError,     /* xGetLastError */               \
    unixCurrentTimeInt64, /* xCurrentTimeInt64 */           \



  }

  /*
  ** All default VFSes for unix are contained in the following array.
  **
  ** Note that the sqlite3_vfs.pNext field of the VFS object is modified
  ** by the SQLite core when the VFS is registered.  So the following
................................................................................
#if SQLITE_ENABLE_LOCKING_STYLE && (OS_VXWORKS || defined(__APPLE__))
    UNIXVFS("unix",          autolockIoFinder ),
#else
    UNIXVFS("unix",          posixIoFinder ),
#endif
    UNIXVFS("unix-none",     nolockIoFinder ),
    UNIXVFS("unix-dotfile",  dotlockIoFinder ),

#if OS_VXWORKS
    UNIXVFS("unix-namedsem", semIoFinder ),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
    UNIXVFS("unix-posix",    posixIoFinder ),
#if !OS_VXWORKS
    UNIXVFS("unix-flock",    flockIoFinder ),
................................................................................


/*
** Initialize and deinitialize the operating system interface.
*/
SQLITE_API int sqlite3_os_init(void){
  static sqlite3_vfs winVfs = {
    2,                   /* iVersion */
    sizeof(winFile),     /* szOsFile */
    MAX_PATH,            /* mxPathname */
    0,                   /* pNext */
    "win32",             /* zName */
    0,                   /* pAppData */
    winOpen,             /* xOpen */
    winDelete,           /* xDelete */
................................................................................
    winDlSym,            /* xDlSym */
    winDlClose,          /* xDlClose */
    winRandomness,       /* xRandomness */
    winSleep,            /* xSleep */
    winCurrentTime,      /* xCurrentTime */
    winGetLastError,     /* xGetLastError */
    winCurrentTimeInt64, /* xCurrentTimeInt64 */



  };

#ifndef SQLITE_OMIT_WAL
  /* get memory map allocation granularity */
  memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
  GetSystemInfo(&winSysInfo);
  assert(winSysInfo.dwAllocationGranularity > 0);
................................................................................
*/

#ifndef _WAL_H_
#define _WAL_H_


#ifdef SQLITE_OMIT_WAL
# define sqlite3WalOpen(x,y,z)                 0
# define sqlite3WalClose(w,x,y,z)              0
# define sqlite3WalBeginReadTransaction(y,z)   0
# define sqlite3WalEndReadTransaction(z)
# define sqlite3WalRead(v,w,x,y,z)             0
# define sqlite3WalDbsize(y)                   0
# define sqlite3WalBeginWriteTransaction(y)    0
# define sqlite3WalEndWriteTransaction(x)      0
# define sqlite3WalUndo(x,y,z)                 0
# define sqlite3WalSavepoint(y,z)
# define sqlite3WalSavepointUndo(y,z)          0
# define sqlite3WalFrames(u,v,w,x,y,z)         0
# define sqlite3WalCheckpoint(u,v,w,x)         0
# define sqlite3WalCallback(z)                 0
# define sqlite3WalExclusiveMode(y,z)          0
# define sqlite3WalHeapMemory(z)               0
#else

#define WAL_SAVEPOINT_NDATA 4

/* Connection to a write-ahead log (WAL) file. 
** There is one object of this type for each pager. 
*/
................................................................................

/* Write a frame or frames to the log. */
SQLITE_PRIVATE int sqlite3WalFrames(Wal *pWal, int, PgHdr *, Pgno, int, int);

/* Copy pages from the log to the database file */ 
SQLITE_PRIVATE int sqlite3WalCheckpoint(
  Wal *pWal,                      /* Write-ahead log connection */



  int sync_flags,                 /* Flags to sync db file with (or 0) */
  int nBuf,                       /* Size of buffer nBuf */
  u8 *zBuf                        /* Temporary buffer to use */


);

/* Return the value to pass to a sqlite3_wal_hook callback, the
** number of frames in the WAL at the point of the last commit since
** sqlite3WalCallback() was called.  If no commits have occurred since
** the last call, then return 0.
*/
................................................................................
  PAGER_INCR(pPager->nRead);
  IOTRACE(("PGIN %p %d\n", pPager, pgno));
  PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
               PAGERID(pPager), pgno, pager_pagehash(pPg)));

  return rc;
}























#ifndef SQLITE_OMIT_WAL
/*
** This function is invoked once for each page that has already been 
** written into the log file when a WAL transaction is rolled back.
** Parameter iPg is the page number of said page. The pCtx argument 
** is actually a pointer to the Pager structure.
................................................................................
    rc = pagerUndoCallback((void *)pPager, pList->pgno);
    pList = pNext;
  }

  return rc;
}


/*
** Update the value of the change-counter at offsets 24 and 92 in
** the header and the sqlite version number at offset 96.
**
** This is an unconditional update.  See also the pager_incr_changecounter()
** routine which only updates the change-counter if the update is actually
** needed, as determined by the pPager->changeCountDone state variable.
*/
static void pager_write_changecounter(PgHdr *pPg){
  u32 change_counter;

  /* Increment the value just read and write it back to byte 24. */
  change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
  put32bits(((char*)pPg->pData)+24, change_counter);

  /* Also store the SQLite version number in bytes 96..99 and in
  ** bytes 92..95 store the change counter for which the version number
  ** is valid. */
  put32bits(((char*)pPg->pData)+92, change_counter);
  put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
}

/*
** This function is a wrapper around sqlite3WalFrames(). As well as logging
** the contents of the list of pages headed by pList (connected by pDirty),
** this function notifies any active backup processes that the pages have
** changed.
**
** The list of pages passed into this routine is always sorted by page number.
** Hence, if page 1 appears anywhere on the list, it will be the first page.
*/ 
static int pagerWalFrames(
  Pager *pPager,                  /* Pager object */
  PgHdr *pList,                   /* List of frames to log */
................................................................................
  assert( pPager->pWal );
#ifdef SQLITE_DEBUG
  /* Verify that the page list is in accending order */
  for(p=pList; p && p->pDirty; p=p->pDirty){
    assert( p->pgno < p->pDirty->pgno );
  }
#endif














  if( pList->pgno==1 ) pager_write_changecounter(pList);
  rc = sqlite3WalFrames(pPager->pWal, 
      pPager->pageSize, pList, nTruncate, isCommit, syncFlags
  );
  if( rc==SQLITE_OK && pPager->pBackup ){
    PgHdr *p;
    for(p=pList; p; p=p->pDirty){
      sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
    }
  }

#ifdef SQLITE_CHECK_PAGES

  for(p=pList; p; p=p->pDirty){
    pager_set_pagehash(p);
  }
#endif

  return rc;
}
................................................................................
*/
SQLITE_PRIVATE sqlite3_backup **sqlite3PagerBackupPtr(Pager *pPager){
  return &pPager->pBackup;
}

#ifndef SQLITE_OMIT_WAL
/*
** This function is called when the user invokes "PRAGMA checkpoint".




*/
SQLITE_PRIVATE int sqlite3PagerCheckpoint(Pager *pPager){
  int rc = SQLITE_OK;
  if( pPager->pWal ){
    u8 *zBuf = (u8 *)pPager->pTmpSpace;
    rc = sqlite3WalCheckpoint(pPager->pWal, pPager->ckptSyncFlags,
                              pPager->pageSize, zBuf);




  }
  return rc;
}

SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager){
  return sqlite3WalCallback(pPager->pWal);
}
................................................................................
*/
static int pagerExclusiveLock(Pager *pPager){
  int rc;                         /* Return code */

  assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
  rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
  if( rc!=SQLITE_OK ){
    /* If the attempt to grab the pending lock failed, release the 
    ** exclusive lock that may have been obtained instead.  */
    pagerUnlockDb(pPager, SHARED_LOCK);
  }

  return rc;
}

/*
................................................................................

  if( rc!=SQLITE_OK ){
    walIteratorFree(p);
  }
  *pp = p;
  return rc;
}





























/*
** Copy as much content as we can from the WAL back into the database file
** in response to an sqlite3_wal_checkpoint() request or the equivalent.
**
** The amount of information copies from WAL to database might be limited
** by active readers.  This routine will never overwrite a database page
................................................................................
**
** The caller must be holding sufficient locks to ensure that no other
** checkpoint is running (in any other thread or process) at the same
** time.
*/
static int walCheckpoint(
  Wal *pWal,                      /* Wal connection */



  int sync_flags,                 /* Flags for OsSync() (or 0) */
  int nBuf,                       /* Size of zBuf in bytes */
  u8 *zBuf                        /* Temporary buffer to use */
){
  int rc;                         /* Return code */
  int szPage;                     /* Database page-size */
  WalIterator *pIter = 0;         /* Wal iterator context */
  u32 iDbpage = 0;                /* Next database page to write */
  u32 iFrame = 0;                 /* Wal frame containing data for iDbpage */
  u32 mxSafeFrame;                /* Max frame that can be backfilled */
  u32 mxPage;                     /* Max database page to write */
  int i;                          /* Loop counter */
  volatile WalCkptInfo *pInfo;    /* The checkpoint status information */


  szPage = (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);

  testcase( szPage<=32768 );
  testcase( szPage>=65536 );
  pInfo = walCkptInfo(pWal);
  if( pInfo->nBackfill>=pWal->hdr.mxFrame ) return SQLITE_OK;

  /* Allocate the iterator */
  rc = walIteratorInit(pWal, &pIter);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  assert( pIter );

  /*** TODO:  Move this test out to the caller.  Make it an assert() here ***/
  if( szPage!=nBuf ){
    rc = SQLITE_CORRUPT_BKPT;
    goto walcheckpoint_out;
  }

  /* Compute in mxSafeFrame the index of the last frame of the WAL that is
  ** safe to write into the database.  Frames beyond mxSafeFrame might
  ** overwrite database pages that are in use by active readers and thus
  ** cannot be backfilled from the WAL.
  */
  mxSafeFrame = pWal->hdr.mxFrame;
  mxPage = pWal->hdr.nPage;
  for(i=1; i<WAL_NREADER; i++){
    u32 y = pInfo->aReadMark[i];
    if( mxSafeFrame>=y ){
      assert( y<=pWal->hdr.mxFrame );
      rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
      if( rc==SQLITE_OK ){
        pInfo->aReadMark[i] = READMARK_NOT_USED;
        walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
      }else if( rc==SQLITE_BUSY ){
        mxSafeFrame = y;

      }else{
        goto walcheckpoint_out;
      }
    }
  }

  if( pInfo->nBackfill<mxSafeFrame
   && (rc = walLockExclusive(pWal, WAL_READ_LOCK(0), 1))==SQLITE_OK
  ){
    i64 nSize;                    /* Current size of database file */
    u32 nBackfill = pInfo->nBackfill;

    /* Sync the WAL to disk */
    if( sync_flags ){
      rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
................................................................................
      if( rc==SQLITE_OK ){
        pInfo->nBackfill = mxSafeFrame;
      }
    }

    /* Release the reader lock held while backfilling */
    walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);


  }else if( rc==SQLITE_BUSY ){
    /* Reset the return code so as not to report a checkpoint failure
    ** just because active readers prevent any backfill.








    */



    rc = SQLITE_OK;





  }



 walcheckpoint_out:
  walIteratorFree(pIter);
  return rc;
}

/*
................................................................................
    ** The EXCLUSIVE lock is not released before returning.
    */
    rc = sqlite3OsLock(pWal->pDbFd, SQLITE_LOCK_EXCLUSIVE);
    if( rc==SQLITE_OK ){
      if( pWal->exclusiveMode==WAL_NORMAL_MODE ){
        pWal->exclusiveMode = WAL_EXCLUSIVE_MODE;
      }
      rc = sqlite3WalCheckpoint(pWal, sync_flags, nBuf, zBuf);


      if( rc==SQLITE_OK ){
        isDelete = 1;
      }
    }

    walIndexClose(pWal, isDelete);
    sqlite3OsClose(pWal->pWalFd);
................................................................................
  u32 mxReadMark;                 /* Largest aReadMark[] value */
  int mxI;                        /* Index of largest aReadMark[] value */
  int i;                          /* Loop counter */
  int rc = SQLITE_OK;             /* Return code  */

  assert( pWal->readLock<0 );     /* Not currently locked */

  /* Take steps to avoid spinning forever if there is a protocol error. */
















  if( cnt>5 ){



    if( cnt>100 ) return SQLITE_PROTOCOL;


    sqlite3OsSleep(pWal->pVfs, 1);
  }

  if( !useWal ){
    rc = walIndexReadHdr(pWal, pChanged);
    if( rc==SQLITE_BUSY ){
      /* If there is not a recovery running in another thread or process
      ** then convert BUSY errors to WAL_RETRY.  If recovery is known to
................................................................................
    u32 thisMark = pInfo->aReadMark[i];
    if( mxReadMark<=thisMark && thisMark<=pWal->hdr.mxFrame ){
      assert( thisMark!=READMARK_NOT_USED );
      mxReadMark = thisMark;
      mxI = i;
    }
  }
  if( mxI==0 ){
    /* If we get here, it means that all of the aReadMark[] entries between
    ** 1 and WAL_NREADER-1 are zero.  Try to initialize aReadMark[1] to
    ** be mxFrame, then retry.
    */
    rc = walLockExclusive(pWal, WAL_READ_LOCK(1), 1);
    if( rc==SQLITE_OK ){
      pInfo->aReadMark[1] = pWal->hdr.mxFrame;
      walUnlockExclusive(pWal, WAL_READ_LOCK(1), 1);
      rc = WAL_RETRY;
    }else if( rc==SQLITE_BUSY ){
      rc = WAL_RETRY;
    }
    return rc;
  }else{

    if( mxReadMark < pWal->hdr.mxFrame ){
      for(i=1; i<WAL_NREADER; i++){
        rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
        if( rc==SQLITE_OK ){
          mxReadMark = pInfo->aReadMark[i] = pWal->hdr.mxFrame;
          mxI = i;
          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
          break;
        }else if( rc!=SQLITE_BUSY ){
          return rc;
        }
      }
    }





    rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
    if( rc ){
      return rc==SQLITE_BUSY ? WAL_RETRY : rc;
    }
    /* Now that the read-lock has been obtained, check that neither the
    ** value in the aReadMark[] array or the contents of the wal-index
................................................................................
SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
  int rc;                         /* Return code */
  int cnt = 0;                    /* Number of TryBeginRead attempts */

  do{
    rc = walTryBeginRead(pWal, pChanged, 0, ++cnt);
  }while( rc==WAL_RETRY );




  return rc;
}

/*
** Finish with a read transaction.  All this does is release the
** read-lock.
*/
................................................................................
  int rc = SQLITE_OK;
  int cnt;

  if( pWal->readLock==0 ){
    volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
    assert( pInfo->nBackfill==pWal->hdr.mxFrame );
    if( pInfo->nBackfill>0 ){


      rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
      if( rc==SQLITE_OK ){
        /* If all readers are using WAL_READ_LOCK(0) (in other words if no
        ** readers are currently using the WAL), then the transactions
        ** frames will overwrite the start of the existing log. Update the
        ** wal-index header to reflect this.
        **
................................................................................
        ** to handle if this transaction is rolled back.
        */
        int i;                    /* Loop counter */
        u32 *aSalt = pWal->hdr.aSalt;       /* Big-endian salt values */
        pWal->nCkpt++;
        pWal->hdr.mxFrame = 0;
        sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
        sqlite3_randomness(4, &aSalt[1]);
        walIndexWriteHdr(pWal);
        pInfo->nBackfill = 0;
        for(i=1; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
        assert( pInfo->aReadMark[0]==0 );
        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
      }else if( rc!=SQLITE_BUSY ){
        return rc;
................................................................................
    walUnlockShared(pWal, WAL_READ_LOCK(0));
    pWal->readLock = -1;
    cnt = 0;
    do{
      int notUsed;
      rc = walTryBeginRead(pWal, &notUsed, 1, ++cnt);
    }while( rc==WAL_RETRY );




  }
  return rc;
}

/* 
** Write a set of frames to the log. The caller must hold the write-lock
** on the log file (obtained using sqlite3WalBeginWriteTransaction()).
................................................................................

/* 
** This routine is called to implement sqlite3_wal_checkpoint() and
** related interfaces.
**
** Obtain a CHECKPOINT lock and then backfill as much information as
** we can from WAL into the database.



*/
SQLITE_PRIVATE int sqlite3WalCheckpoint(
  Wal *pWal,                      /* Wal connection */



  int sync_flags,                 /* Flags to sync db file with (or 0) */
  int nBuf,                       /* Size of temporary buffer */
  u8 *zBuf                        /* Temporary buffer to use */


){
  int rc;                         /* Return code */
  int isChanged = 0;              /* True if a new wal-index header is loaded */


  assert( pWal->ckptLock==0 );


  WALTRACE(("WAL%p: checkpoint begins\n", pWal));
  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
  if( rc ){
    /* Usually this is SQLITE_BUSY meaning that another thread or process
    ** is already running a checkpoint, or maybe a recovery.  But it might
    ** also be SQLITE_IOERR. */
    return rc;
  }
  pWal->ckptLock = 1;

  /* Copy data from the log to the database file. */




















  rc = walIndexReadHdr(pWal, &isChanged);



  if( rc==SQLITE_OK ){



    rc = walCheckpoint(pWal, sync_flags, nBuf, zBuf);
  }








  if( isChanged ){
    /* If a new wal-index header was loaded before the checkpoint was 
    ** performed, then the pager-cache associated with pWal is now
    ** out of date. So zero the cached wal-index header to ensure that
    ** next time the pager opens a snapshot on this database it knows that
    ** the cache needs to be reset.
    */
    memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
  }

  /* Release the locks. */

  walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
  pWal->ckptLock = 0;
  WALTRACE(("WAL%p: checkpoint %s\n", pWal, rc ? "failed" : "ok"));
  return rc;
}

/* Return the value to pass to a sqlite3_wal_hook callback, the
** number of frames in the WAL at the point of the last commit since
** sqlite3WalCallback() was called.  If no commits have occurred since
** the last call, then return 0.
*/
................................................................................
**      *     zero or more pages numbers of leaves
*/


/* The following value is the maximum cell size assuming a maximum page
** size give above.
*/
#define MX_CELL_SIZE(pBt)  (pBt->pageSize-8)

/* The maximum number of cells on a single page of the database.  This
** assumes a minimum cell size of 6 bytes  (4 bytes for the cell itself
** plus 2 bytes for the index to the cell in the page header).  Such
** small cells will be rare, but they are possible.
*/
#define MX_CELL(pBt) ((pBt->pageSize-8)/6)
................................................................................
** points to the same BtShared object.  The database cache and the
** schema associated with the database file are all contained within
** the BtShared object.
**
** All fields in this structure are accessed under sqlite3.mutex.
** The pBt pointer itself may not be changed while there exists cursors 
** in the referenced BtShared that point back to this Btree since those
** cursors have to do go through this Btree to find their BtShared and
** they often do so without holding sqlite3.mutex.
*/
struct Btree {
  sqlite3 *db;       /* The database connection holding this btree */
  BtShared *pBt;     /* Sharable content of this btree */
  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
  u8 sharable;       /* True if we can share pBt with another db */
................................................................................
  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */
  u32 pageSize;         /* Total number of bytes on a page */
  u32 usableSize;       /* Number of usable bytes on each page */
  int nTransaction;     /* Number of open transactions (read + write) */
  u32 nPage;            /* Number of pages in the database */
  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this struct */
  Bitvec *pHasContent;  /* Set of pages moved to free-list this transaction */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nRef;             /* Number of references to this structure */
  BtShared *pNext;      /* Next on a list of sharable BtShared structs */
  BtLock *pLock;        /* List of locks held on this shared-btree struct */
  Btree *pWriter;       /* Btree with currently open write transaction */
  u8 isExclusive;       /* True if pWriter has an EXCLUSIVE lock on the db */
................................................................................
}

/*
** Release the BtShared mutex associated with B-Tree handle p and
** clear the p->locked boolean.
*/
static void unlockBtreeMutex(Btree *p){

  assert( p->locked==1 );
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  assert( sqlite3_mutex_held(p->db->mutex) );
  assert( p->db==p->pBt->db );

  sqlite3_mutex_leave(p->pBt->mutex);
  p->locked = 0;
}

/*
** Enter a mutex on the given BTree object.
**
** If the object is not sharable, then no mutex is ever required
................................................................................
** Enter the mutexes in accending order by BtShared pointer address
** to avoid the possibility of deadlock when two threads with
** two or more btrees in common both try to lock all their btrees
** at the same instant.
*/
SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
  int i;
  Btree *p, *pLater;
  assert( sqlite3_mutex_held(db->mutex) );
  for(i=0; i<db->nDb; i++){
    p = db->aDb[i].pBt;
    assert( !p || (p->locked==0 && p->sharable) || p->pBt->db==p->db );
    if( p && p->sharable ){
      p->wantToLock++;
      if( !p->locked ){
        assert( p->wantToLock==1 );
        while( p->pPrev ) p = p->pPrev;
        /* Reason for ALWAYS:  There must be at least on unlocked Btree in
        ** the chain.  Otherwise the !p->locked test above would have failed */
        while( p->locked && ALWAYS(p->pNext) ) p = p->pNext;
        for(pLater = p->pNext; pLater; pLater=pLater->pNext){
          if( pLater->locked ){
            unlockBtreeMutex(pLater);
          }
        }
        while( p ){
          lockBtreeMutex(p);
          p = p->pNext;
        }
      }
    }
  }
}
SQLITE_PRIVATE void sqlite3BtreeLeaveAll(sqlite3 *db){
  int i;
  Btree *p;
  assert( sqlite3_mutex_held(db->mutex) );
  for(i=0; i<db->nDb; i++){
    p = db->aDb[i].pBt;
    if( p && p->sharable ){
      assert( p->wantToLock>0 );
      p->wantToLock--;
      if( p->wantToLock==0 ){
        unlockBtreeMutex(p);
      }
    }
  }






}

#ifndef NDEBUG
/*
** Return true if the current thread holds the database connection
** mutex and all required BtShared mutexes.
**
** This routine is used inside assert() statements only.
................................................................................
      return 0;
    }
  }
  return 1;
}
#endif /* NDEBUG */


/*
** Add a new Btree pointer to a BtreeMutexArray. 
** if the pointer can possibly be shared with
** another database connection.

**
** The pointers are kept in sorted order by pBtree->pBt.  That
** way when we go to enter all the mutexes, we can enter them
** in order without every having to backup and retry and without
** worrying about deadlock.
**

** The number of shared btrees will always be small (usually 0 or 1)
** so an insertion sort is an adequate algorithm here.
*/

SQLITE_PRIVATE void sqlite3BtreeMutexArrayInsert(BtreeMutexArray *pArray, Btree *pBtree){
  int i, j;
  BtShared *pBt;
  if( pBtree==0 || pBtree->sharable==0 ) return;
#ifndef NDEBUG
  {

    for(i=0; i<pArray->nMutex; i++){
      assert( pArray->aBtree[i]!=pBtree );

    }
  }
#endif
  assert( pArray->nMutex>=0 );
  assert( pArray->nMutex<ArraySize(pArray->aBtree)-1 );
  pBt = pBtree->pBt;
  for(i=0; i<pArray->nMutex; i++){
    assert( pArray->aBtree[i]!=pBtree );
    if( pArray->aBtree[i]->pBt>pBt ){
      for(j=pArray->nMutex; j>i; j--){
        pArray->aBtree[j] = pArray->aBtree[j-1];
      }
      pArray->aBtree[i] = pBtree;
      pArray->nMutex++;
      return;
    }
  }
  pArray->aBtree[pArray->nMutex++] = pBtree;
}


/*
** Enter the mutex of every btree in the array.  This routine is
** called at the beginning of sqlite3VdbeExec().  The mutexes are
** exited at the end of the same function.




*/
SQLITE_PRIVATE void sqlite3BtreeMutexArrayEnter(BtreeMutexArray *pArray){
  int i;
  for(i=0; i<pArray->nMutex; i++){
    Btree *p = pArray->aBtree[i];
    /* Some basic sanity checking */
    assert( i==0 || pArray->aBtree[i-1]->pBt<p->pBt );
    assert( !p->locked || p->wantToLock>0 );

    /* We should already hold a lock on the database connection */
    assert( sqlite3_mutex_held(p->db->mutex) );

    /* The Btree is sharable because only sharable Btrees are entered
    ** into the array in the first place. */
    assert( p->sharable );

    p->wantToLock++;
    if( !p->locked ){
      lockBtreeMutex(p);
    }
  }
}

/*
** Leave the mutex of every btree in the group.


*/
SQLITE_PRIVATE void sqlite3BtreeMutexArrayLeave(BtreeMutexArray *pArray){
  int i;
  for(i=0; i<pArray->nMutex; i++){
    Btree *p = pArray->aBtree[i];
    /* Some basic sanity checking */
    assert( i==0 || pArray->aBtree[i-1]->pBt<p->pBt );
    assert( p->locked );
    assert( p->wantToLock>0 );

    /* We should already hold a lock on the database connection */
    assert( sqlite3_mutex_held(p->db->mutex) );

    p->wantToLock--;
    if( p->wantToLock==0 ){
      unlockBtreeMutex(p);
    }
  }
}

#else
SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
  p->pBt->db = p->db;
}
SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
  int i;
  for(i=0; i<db->nDb; i++){
    Btree *p = db->aDb[i].pBt;
................................................................................
  ** and the cell content area.  The btreeInitPage() call has already
  ** validated the freelist.  Given that the freelist is valid, there
  ** is no way that the allocation can extend off the end of the page.
  ** The assert() below verifies the previous sentence.
  */
  top -= nByte;
  put2byte(&data[hdr+5], top);
  assert( top+nByte <= pPage->pBt->usableSize );
  *pIdx = top;
  return SQLITE_OK;
}

/*
** Return a section of the pPage->aData to the freelist.
** The first byte of the new free block is pPage->aDisk[start]
................................................................................
  int addr, pbegin, hdr;
  int iLast;                        /* Largest possible freeblock offset */
  unsigned char *data = pPage->aData;

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( start>=pPage->hdrOffset+6+pPage->childPtrSize );
  assert( (start + size)<=pPage->pBt->usableSize );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( size>=0 );   /* Minimum cell size is 4 */

  if( pPage->pBt->secureDelete ){
    /* Overwrite deleted information with zeros when the secure_delete
    ** option is enabled */
    memset(&data[start], 0, size);
................................................................................
  pPage->nFree = pPage->nFree + (u16)size;

  /* Coalesce adjacent free blocks */
  addr = hdr + 1;
  while( (pbegin = get2byte(&data[addr]))>0 ){
    int pnext, psize, x;
    assert( pbegin>addr );
    assert( pbegin<=pPage->pBt->usableSize-4 );
    pnext = get2byte(&data[pbegin]);
    psize = get2byte(&data[pbegin+2]);
    if( pbegin + psize + 3 >= pnext && pnext>0 ){
      int frag = pnext - (pbegin+psize);
      if( (frag<0) || (frag>(int)data[hdr+7]) ){
        return SQLITE_CORRUPT_BKPT;
      }
................................................................................
  sqlite3BtreeEnter(p);
  assert( pBt && pBt->pPager );
  rc = sqlite3PagerNosync(pBt->pPager);
  sqlite3BtreeLeave(p);
  return rc;
}

#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
/*
** Change the default pages size and the number of reserved bytes per page.
** Or, if the page size has already been fixed, return SQLITE_READONLY 
** without changing anything.
**
** The page size must be a power of 2 between 512 and 65536.  If the page
** size supplied does not meet this constraint then the page size is not
................................................................................
/*
** Return the currently defined page size
*/
SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree *p){
  return p->pBt->pageSize;
}


/*
** Return the number of bytes of space at the end of every page that
** are intentually left unused.  This is the "reserved" space that is
** sometimes used by extensions.
*/
SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree *p){
  int n;
................................................................................
      pBt->usableSize = usableSize;
      pBt->pageSize = pageSize;
      freeTempSpace(pBt);
      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
                                   pageSize-usableSize);
      return rc;
    }
    if( (pBt->db->flags & SQLITE_RecoveryMode)==0 && nPageHeader>nPageFile ){
      rc = SQLITE_CORRUPT_BKPT;
      goto page1_init_failed;
    }
    if( usableSize<480 ){
      goto page1_init_failed;
    }
    pBt->pageSize = pageSize;
................................................................................
** sqlite3BtreeCommitPhaseOne() routine does the first phase and should
** be invoked prior to calling this routine.  The sqlite3BtreeCommitPhaseOne()
** routine did all the work of writing information out to disk and flushing the
** contents so that they are written onto the disk platter.  All this
** routine has to do is delete or truncate or zero the header in the
** the rollback journal (which causes the transaction to commit) and
** drop locks.











**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree *p){

  if( p->inTrans==TRANS_NONE ) return SQLITE_OK;
  sqlite3BtreeEnter(p);
  btreeIntegrity(p);

  /* If the handle has a write-transaction open, commit the shared-btrees 
  ** transaction and set the shared state to TRANS_READ.
................................................................................
  */
  if( p->inTrans==TRANS_WRITE ){
    int rc;
    BtShared *pBt = p->pBt;
    assert( pBt->inTransaction==TRANS_WRITE );
    assert( pBt->nTransaction>0 );
    rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
    if( rc!=SQLITE_OK ){
      sqlite3BtreeLeave(p);
      return rc;
    }
    pBt->inTransaction = TRANS_READ;
  }

  btreeEndTransaction(p);
................................................................................
** Do both phases of a commit.
*/
SQLITE_PRIVATE int sqlite3BtreeCommit(Btree *p){
  int rc;
  sqlite3BtreeEnter(p);
  rc = sqlite3BtreeCommitPhaseOne(p, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3BtreeCommitPhaseTwo(p);
  }
  sqlite3BtreeLeave(p);
  return rc;
}

#ifndef NDEBUG
/*
................................................................................
        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }

      k = get4byte(&pTrunk->aData[4]);
      if( k==0 && !searchList ){
        /* The trunk has no leaves and the list is not being searched. 
        ** So extract the trunk page itself and use it as the newly 
        ** allocated page */
        assert( pPrevTrunk==0 );
        rc = sqlite3PagerWrite(pTrunk->pDbPage);
        if( rc ){
................................................................................
        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
#endif
      }else if( k>0 ){
        /* Extract a leaf from the trunk */
        u32 closest;
        Pgno iPage;
        unsigned char *aData = pTrunk->aData;
        rc = sqlite3PagerWrite(pTrunk->pDbPage);
        if( rc ){
          goto end_allocate_page;
        }
        if( nearby>0 ){
          u32 i;
          int dist;
          closest = 0;
          dist = get4byte(&aData[8]) - nearby;
          if( dist<0 ) dist = -dist;
          for(i=1; i<k; i++){
            int d2 = get4byte(&aData[8+i*4]) - nearby;
            if( d2<0 ) d2 = -d2;
            if( d2<dist ){
              closest = i;
              dist = d2;
            }
          }
        }else{
          closest = 0;
................................................................................
        testcase( iPage==mxPage );
        if( !searchList || iPage==nearby ){
          int noContent;
          *pPgno = iPage;
          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
                 ": %d more free pages\n",
                 *pPgno, closest+1, k, pTrunk->pgno, n-1));


          if( closest<k-1 ){
            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
          }
          put4byte(&aData[4], k-1);
          assert( sqlite3PagerIswriteable(pTrunk->pDbPage) );
          noContent = !btreeGetHasContent(pBt, *pPgno);
          rc = btreeGetPage(pBt, *pPgno, ppPage, noContent);
          if( rc==SQLITE_OK ){
            rc = sqlite3PagerWrite((*ppPage)->pDbPage);
            if( rc!=SQLITE_OK ){
              releasePage(*ppPage);
            }
................................................................................
      releasePage(*ppPage);
      return SQLITE_CORRUPT_BKPT;
    }
    (*ppPage)->isInit = 0;
  }else{
    *ppPage = 0;
  }

  return rc;
}

/*
** This function is used to add page iPage to the database file free-list. 
** It is assumed that the page is not already a part of the free-list.
**
................................................................................
    end = cellOffset + 2*pPage->nCell;
    ins = cellOffset + 2*i;
    rc = allocateSpace(pPage, sz, &idx);
    if( rc ){ *pRC = rc; return; }
    /* The allocateSpace() routine guarantees the following two properties
    ** if it returns success */
    assert( idx >= end+2 );
    assert( idx+sz <= pPage->pBt->usableSize );
    pPage->nCell++;
    pPage->nFree -= (u16)(2 + sz);
    memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
    if( iChild ){
      put4byte(&data[idx], iChild);
    }
    for(j=end, ptr=&data[j]; j>ins; j-=2, ptr-=2){
................................................................................
  int cellbody;     /* Address of next cell body */
  u8 * const data = pPage->aData;             /* Pointer to data for pPage */
  const int hdr = pPage->hdrOffset;           /* Offset of header on pPage */
  const int nUsable = pPage->pBt->usableSize; /* Usable size of page */

  assert( pPage->nOverflow==0 );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  assert( nCell>=0 && nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921);
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );

  /* Check that the page has just been zeroed by zeroPage() */
  assert( pPage->nCell==0 );
  assert( get2byteNotZero(&data[hdr+5])==nUsable );

  pCellptr = &data[pPage->cellOffset + nCell*2];
................................................................................
    int const iToHdr = ((pTo->pgno==1) ? 100 : 0);
    int rc;
    int iData;
  
  
    assert( pFrom->isInit );
    assert( pFrom->nFree>=iToHdr );
    assert( get2byte(&aFrom[iFromHdr+5])<=pBt->usableSize );
  
    /* Copy the b-tree node content from page pFrom to page pTo. */
    iData = get2byte(&aFrom[iFromHdr+5]);
    memcpy(&aTo[iData], &aFrom[iData], pBt->usableSize-iData);
    memcpy(&aTo[iToHdr], &aFrom[iFromHdr], pFrom->cellOffset + 2*pFrom->nCell);
  
    /* Reinitialize page pTo so that the contents of the MemPage structure
................................................................................
      u16 sz = (u16)szNew[i];
      u8 *pTemp;
      assert( nCell<nMaxCells );
      szCell[nCell] = sz;
      pTemp = &aSpace1[iSpace1];
      iSpace1 += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iSpace1<=pBt->pageSize );
      memcpy(pTemp, apDiv[i], sz);
      apCell[nCell] = pTemp+leafCorrection;
      assert( leafCorrection==0 || leafCorrection==4 );
      szCell[nCell] = szCell[nCell] - leafCorrection;
      if( !pOld->leaf ){
        assert( leafCorrection==0 );
        assert( pOld->hdrOffset==0 );
................................................................................
    for(j=i+1; j<k; j++){
      if( apNew[j]->pgno<(unsigned)minV ){
        minI = j;
        minV = apNew[j]->pgno;
      }
    }
    if( minI>i ){
      int t;
      MemPage *pT;
      t = apNew[i]->pgno;
      pT = apNew[i];
      apNew[i] = apNew[minI];
      apNew[minI] = pT;
    }
  }
  TRACE(("new: %d(%d) %d(%d) %d(%d) %d(%d) %d(%d)\n",
    apNew[0]->pgno, szNew[0],
................................................................................
        if( szCell[j]==4 ){
          assert(leafCorrection==4);
          sz = cellSizePtr(pParent, pCell);
        }
      }
      iOvflSpace += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iOvflSpace<=pBt->pageSize );
      insertCell(pParent, nxDiv, pCell, sz, pTemp, pNew->pgno, &rc);
      if( rc!=SQLITE_OK ) goto balance_cleanup;
      assert( sqlite3PagerIswriteable(pParent->pDbPage) );

      j++;
      nxDiv++;
    }
................................................................................
  assert( pPage->isInit );
  allocateTempSpace(pBt);
  newCell = pBt->pTmpSpace;
  if( newCell==0 ) return SQLITE_NOMEM;
  rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
  if( rc ) goto end_insert;
  assert( szNew==cellSizePtr(pPage, newCell) );
  assert( szNew<=MX_CELL_SIZE(pBt) );
  idx = pCur->aiIdx[pCur->iPage];
  if( loc==0 ){
    u16 szOld;
    assert( idx<pPage->nCell );
    rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc ){
      goto end_insert;
................................................................................
    MemPage *pLeaf = pCur->apPage[pCur->iPage];
    int nCell;
    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
    unsigned char *pTmp;

    pCell = findCell(pLeaf, pLeaf->nCell-1);
    nCell = cellSizePtr(pLeaf, pCell);
    assert( MX_CELL_SIZE(pBt)>=nCell );

    allocateTempSpace(pBt);
    pTmp = pBt->pTmpSpace;

    rc = sqlite3PagerWrite(pLeaf->pDbPage);
    insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
    dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
................................................................................

#ifndef SQLITE_OMIT_WAL
/*
** Run a checkpoint on the Btree passed as the first argument.
**
** Return SQLITE_LOCKED if this or any other connection has an open 
** transaction on the shared-cache the argument Btree is connected to.


*/
SQLITE_PRIVATE int sqlite3BtreeCheckpoint(Btree *p){
  int rc = SQLITE_OK;
  if( p ){
    BtShared *pBt = p->pBt;
    sqlite3BtreeEnter(p);
    if( pBt->inTransaction!=TRANS_NONE ){
      rc = SQLITE_LOCKED;
    }else{
      rc = sqlite3PagerCheckpoint(pBt->pPager);
    }
    sqlite3BtreeLeave(p);
  }
  return rc;
}
#endif

................................................................................
**
** If the nBytes parameter is 0 and the blob of memory has not yet been
** allocated, a null pointer is returned. If the blob has already been
** allocated, it is returned as normal.
**
** Just before the shared-btree is closed, the function passed as the 
** xFree argument when the memory allocation was made is invoked on the 
** blob of allocated memory. This function should not call sqlite3_free()
** on the memory, the btree layer does that.
*/
SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  if( !pBt->pSchema && nBytes ){
    pBt->pSchema = sqlite3DbMallocZero(0, nBytes);
................................................................................
*/
static int backupOnePage(sqlite3_backup *p, Pgno iSrcPg, const u8 *zSrcData){
  Pager * const pDestPager = sqlite3BtreePager(p->pDest);
  const int nSrcPgsz = sqlite3BtreeGetPageSize(p->pSrc);
  int nDestPgsz = sqlite3BtreeGetPageSize(p->pDest);
  const int nCopy = MIN(nSrcPgsz, nDestPgsz);
  const i64 iEnd = (i64)iSrcPg*(i64)nSrcPgsz;





  int rc = SQLITE_OK;
  i64 iOff;

  assert( p->bDestLocked );
  assert( !isFatalError(p->rc) );
  assert( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) );
................................................................................
  */
  if( nSrcPgsz!=nDestPgsz && sqlite3PagerIsMemdb(pDestPager) ){
    rc = SQLITE_READONLY;
  }

#ifdef SQLITE_HAS_CODEC
  /* Backup is not possible if the page size of the destination is changing
  ** a a codec is in use.
  */
  if( nSrcPgsz!=nDestPgsz && sqlite3PagerGetCodec(pDestPager)!=0 ){
    rc = SQLITE_READONLY;
  }











#endif

  /* This loop runs once for each destination page spanned by the source 
  ** page. For each iteration, variable iOff is set to the byte offset
  ** of the destination page.
  */
  for(iOff=iEnd-(i64)nSrcPgsz; rc==SQLITE_OK && iOff<iEnd; iOff+=nDestPgsz){
................................................................................
    */
    if( rc==SQLITE_DONE 
     && (rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1))==SQLITE_OK
    ){
      int nDestTruncate;
  
      if( p->pDestDb ){
        sqlite3ResetInternalSchema(p->pDestDb, 0);
      }

      /* Set nDestTruncate to the final number of pages in the destination
      ** database. The complication here is that the destination page
      ** size may be different to the source page size. 
      **
      ** If the source page size is smaller than the destination page size, 
................................................................................
        }
      }else{
        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
      }
  
      /* Finish committing the transaction to the destination database. */
      if( SQLITE_OK==rc
       && SQLITE_OK==(rc = sqlite3BtreeCommitPhaseTwo(p->pDest))
      ){
        rc = SQLITE_DONE;
      }
    }
  
    /* If bCloseTrans is true, then this function opened a read transaction
    ** on the source database. Close the read transaction here. There is
    ** no need to check the return values of the btree methods here, as
    ** "committing" a read-only transaction cannot fail.
    */
    if( bCloseTrans ){
      TESTONLY( int rc2 );
      TESTONLY( rc2  = ) sqlite3BtreeCommitPhaseOne(p->pSrc, 0);
      TESTONLY( rc2 |= ) sqlite3BtreeCommitPhaseTwo(p->pSrc);
      assert( rc2==SQLITE_OK );
    }
  
    if( rc==SQLITE_IOERR_NOMEM ){
      rc = SQLITE_NOMEM;
    }
    p->rc = rc;
................................................................................
  for(p=pBackup; p; p=p->pNext){
    assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
    if( !isFatalError(p->rc) && iPage<p->iNext ){
      /* The backup process p has already copied page iPage. But now it
      ** has been modified by a transaction on the source pager. Copy
      ** the new data into the backup.
      */



      int rc = backupOnePage(p, iPage, aData);

      assert( rc!=SQLITE_BUSY && rc!=SQLITE_LOCKED );
      if( rc!=SQLITE_OK ){
        p->rc = rc;
      }
    }
  }
}
................................................................................
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
  flags = pMem->flags;
  if( flags & MEM_Int ){
    return pMem->u.i;
  }else if( flags & MEM_Real ){
    return doubleToInt64(pMem->r);
  }else if( flags & (MEM_Str|MEM_Blob) ){
    i64 value;
    assert( pMem->z || pMem->n==0 );
    testcase( pMem->z==0 );
    sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
    return value;
  }else{
    return 0;
  }
................................................................................
    if( enc!=SQLITE_UTF8 ){
      sqlite3VdbeChangeEncoding(pVal, enc);
    }
  }else if( op==TK_UMINUS ) {
    /* This branch happens for multiple negative signs.  Ex: -(-5) */
    if( SQLITE_OK==sqlite3ValueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal) ){
      sqlite3VdbeMemNumerify(pVal);
      pVal->u.i = -1 * pVal->u.i;
      /* (double)-1 In case of SQLITE_OMIT_FLOATING_POINT... */

      pVal->r = (double)-1 * pVal->r;




      sqlite3ValueApplyAffinity(pVal, affinity, enc);
    }



  }
#ifndef SQLITE_OMIT_BLOB_LITERAL
  else if( op==TK_BLOB ){
    int nVal;
    assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
    assert( pExpr->u.zToken[1]=='\'' );
    pVal = sqlite3ValueNew(db);
................................................................................
  pOp->p5 = 0;
  pOp->p1 = p1;
  pOp->p2 = p2;
  pOp->p3 = p3;
  pOp->p4.p = 0;
  pOp->p4type = P4_NOTUSED;
  p->expired = 0;






#ifdef SQLITE_DEBUG
  pOp->zComment = 0;
  if( sqlite3VdbeAddopTrace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]);
#endif
#ifdef VDBE_PROFILE
  pOp->cycles = 0;
  pOp->cnt = 0;
................................................................................
** returned program.
*/
SQLITE_PRIVATE VdbeOp *sqlite3VdbeTakeOpArray(Vdbe *p, int *pnOp, int *pnMaxArg){
  VdbeOp *aOp = p->aOp;
  assert( aOp && !p->db->mallocFailed );

  /* Check that sqlite3VdbeUsesBtree() was not called on this VM */
  assert( p->aMutex.nMutex==0 );

  resolveP2Values(p, pnMaxArg);
  *pnOp = p->nOp;
  p->aOp = 0;
  return aOp;
}

................................................................................
}

/*
** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.
*/
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe *p, int addr){

  sqlite3VdbeChangeP2(p, addr, p->nOp);
}


/*
** If the input FuncDef structure is ephemeral, then free it.  If
** the FuncDef is not ephermal, then do nothing.
................................................................................
  return zP4;
}
#endif

/*
** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
**
** The prepared statement has to know in advance which Btree objects
** will be used so that it can acquire mutexes on them all in sorted
** order (via sqlite3VdbeMutexArrayEnter().  Mutexes are acquired
** in order (and released in reverse order) to avoid deadlocks.
*/
SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe *p, int i){
  int mask;
  assert( i>=0 && i<p->db->nDb && i<sizeof(u32)*8 );
  assert( i<(int)sizeof(p->btreeMask)*8 );
  mask = ((u32)1)<<i;
  if( (p->btreeMask & mask)==0 ){
    p->btreeMask |= mask;
    sqlite3BtreeMutexArrayInsert(&p->aMutex, p->db->aDb[i].pBt);


  }
}































































#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){
  char *zP4;
................................................................................
** Also release any dynamic memory held by the VM in the Vdbe.aMem memory 
** cell array. This is necessary as the memory cell array may contain
** pointers to VdbeFrame objects, which may in turn contain pointers to
** open cursors.
*/
static void closeAllCursors(Vdbe *p){
  if( p->pFrame ){
    VdbeFrame *pFrame = p->pFrame;
    for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
    sqlite3VdbeFrameRestore(pFrame);
  }
  p->pFrame = 0;
  p->nFrame = 0;

  if( p->apCsr ){
................................................................................
    ** If one of the BtreeCommitPhaseOne() calls fails, this indicates an
    ** IO error while deleting or truncating a journal file. It is unlikely,
    ** but could happen. In this case abandon processing and return the error.
    */
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
      Btree *pBt = db->aDb[i].pBt;
      if( pBt ){
        rc = sqlite3BtreeCommitPhaseTwo(pBt);
      }
    }
    if( rc==SQLITE_OK ){
      sqlite3VtabCommit(db);
    }
  }

................................................................................
    ** may be lying around. Returning an error code won't help matters.
    */
    disable_simulated_io_errors();
    sqlite3BeginBenignMalloc();
    for(i=0; i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt ){
        sqlite3BtreeCommitPhaseTwo(pBt);
      }
    }
    sqlite3EndBenignMalloc();
    enable_simulated_io_errors();

    sqlite3VtabCommit(db);
  }
................................................................................
    if( eOp==SAVEPOINT_ROLLBACK ){
      db->nDeferredCons = p->nStmtDefCons;
    }
  }
  return rc;
}

/*
** If SQLite is compiled to support shared-cache mode and to be threadsafe,
** this routine obtains the mutex associated with each BtShared structure
** that may be accessed by the VM passed as an argument. In doing so it
** sets the BtShared.db member of each of the BtShared structures, ensuring
** that the correct busy-handler callback is invoked if required.
**
** If SQLite is not threadsafe but does support shared-cache mode, then
** sqlite3BtreeEnterAll() is invoked to set the BtShared.db variables
** of all of BtShared structures accessible via the database handle 
** associated with the VM. Of course only a subset of these structures
** will be accessed by the VM, and we could use Vdbe.btreeMask to figure
** that subset out, but there is no advantage to doing so.
**
** If SQLite is not threadsafe and does not support shared-cache mode, this
** function is a no-op.
*/
#ifndef SQLITE_OMIT_SHARED_CACHE
SQLITE_PRIVATE void sqlite3VdbeMutexArrayEnter(Vdbe *p){
#if SQLITE_THREADSAFE
  sqlite3BtreeMutexArrayEnter(&p->aMutex);
#else
  sqlite3BtreeEnterAll(p->db);
#endif
}
#endif

/*
** This function is called when a transaction opened by the database 
** handle associated with the VM passed as an argument is about to be 
** committed. If there are outstanding deferred foreign key constraint
** violations, return SQLITE_ERROR. Otherwise, SQLITE_OK.
**
** If there are outstanding FK violations and this function returns 
................................................................................
  /* No commit or rollback needed if the program never started */
  if( p->pc>=0 ){
    int mrc;   /* Primary error code from p->rc */
    int eStatementOp = 0;
    int isSpecialError;            /* Set to true if a 'special' error */

    /* Lock all btrees used by the statement */
    sqlite3VdbeMutexArrayEnter(p);

    /* Check for one of the special errors */
    mrc = p->rc & 0xff;
    assert( p->rc!=SQLITE_IOERR_BLOCKED );  /* This error no longer exists */
    isSpecialError = mrc==SQLITE_NOMEM || mrc==SQLITE_IOERR
                     || mrc==SQLITE_INTERRUPT || mrc==SQLITE_FULL;
    if( isSpecialError ){
................................................................................
    ** above has occurred. 
    */
    if( !sqlite3VtabInSync(db) 
     && db->autoCommit 
     && db->writeVdbeCnt==(p->readOnly==0) 
    ){
      if( p->rc==SQLITE_OK || (p->errorAction==OE_Fail && !isSpecialError) ){
        if( sqlite3VdbeCheckFk(p, 1) ){
          sqlite3BtreeMutexArrayLeave(&p->aMutex);


          return SQLITE_ERROR;
        }


        /* The auto-commit flag is true, the vdbe program was successful 
        ** or hit an 'OR FAIL' constraint and there are no deferred foreign
        ** key constraints to hold up the transaction. This means a commit 
        ** is required.  */
        rc = vdbeCommit(db, p);

        if( rc==SQLITE_BUSY ){
          sqlite3BtreeMutexArrayLeave(&p->aMutex);

          return SQLITE_BUSY;
        }else if( rc!=SQLITE_OK ){
          p->rc = rc;
          sqlite3RollbackAll(db);
        }else{
          db->nDeferredCons = 0;
          sqlite3CommitInternalChanges(db);
................................................................................
        sqlite3VdbeSetChanges(db, 0);
      }
      p->nChange = 0;
    }
  
    /* Rollback or commit any schema changes that occurred. */
    if( p->rc!=SQLITE_OK && db->flags&SQLITE_InternChanges ){
      sqlite3ResetInternalSchema(db, 0);
      db->flags = (db->flags | SQLITE_InternChanges);
    }

    /* Release the locks */
    sqlite3BtreeMutexArrayLeave(&p->aMutex);
  }

  /* We have successfully halted and closed the VM.  Record this fact. */
  if( p->pc>=0 ){
    db->activeVdbeCnt--;
    if( !p->readOnly ){
      db->writeVdbeCnt--;
................................................................................
  ** to invoke any required unlock-notify callbacks.
  */
  if( db->autoCommit ){
    sqlite3ConnectionUnlocked(db);
  }

  assert( db->activeVdbeCnt>0 || db->autoCommit==0 || db->nStatement==0 );
  return SQLITE_OK;
}


/*
** Each VDBE holds the result of the most recent sqlite3_step() call
** in p->rc.  This routine sets that result back to SQLITE_OK.
*/
................................................................................
    /* Figure out whether to use 1, 2, 4, 6 or 8 bytes. */
#   define MAX_6BYTE ((((i64)0x00008000)<<32)-1)
    i64 i = pMem->u.i;
    u64 u;
    if( file_format>=4 && (i&1)==i ){
      return 8+(u32)i;
    }





    u = i<0 ? -i : i;

    if( u<=127 ) return 1;
    if( u<=32767 ) return 2;
    if( u<=8388607 ) return 3;
    if( u<=2147483647 ) return 4;
    if( u<=MAX_6BYTE ) return 5;
    return 6;
  }
................................................................................
** Check to see if column iCol of the given statement is valid.  If
** it is, return a pointer to the Mem for the value of that column.
** If iCol is not valid, return a pointer to a Mem which has a value
** of NULL.
*/
static Mem *columnMem(sqlite3_stmt *pStmt, int i){
  Vdbe *pVm;
  int vals;
  Mem *pOut;

  pVm = (Vdbe *)pStmt;
  if( pVm && pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
    sqlite3_mutex_enter(pVm->db->mutex);
    vals = sqlite3_data_count(pStmt);
    pOut = &pVm->pResultSet[i];
  }else{
    /* If the value passed as the second argument is out of range, return
    ** a pointer to the following static Mem object which contains the
    ** value SQL NULL. Even though the Mem structure contains an element
    ** of type i64, on certain architecture (x86) with certain compiler
    ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
................................................................................
    ** this assert() from failing, when building with SQLITE_DEBUG defined
    ** using gcc, force nullMem to be 8-byte aligned using the magical
    ** __attribute__((aligned(8))) macro.  */
    static const Mem nullMem 
#if defined(SQLITE_DEBUG) && defined(__GNUC__)
      __attribute__((aligned(8))) 
#endif
      = {0, "", (double)0, {0}, 0, MEM_Null, SQLITE_NULL, 0, 0, 0 };





    if( pVm && ALWAYS(pVm->db) ){
      sqlite3_mutex_enter(pVm->db->mutex);
      sqlite3Error(pVm->db, SQLITE_RANGE, 0);
    }
    pOut = (Mem*)&nullMem;
  }
................................................................................
                      db->aLimit[SQLITE_LIMIT_LENGTH]);
  out.db = db;
  if( db->vdbeExecCnt>1 ){
    while( *zRawSql ){
      const char *zStart = zRawSql;
      while( *(zRawSql++)!='\n' && *zRawSql );
      sqlite3StrAccumAppend(&out, "-- ", 3);
      sqlite3StrAccumAppend(&out, zStart, zRawSql-zStart);
    }
  }else{
    while( zRawSql[0] ){
      n = findNextHostParameter(zRawSql, &nToken);
      assert( n>0 );
      sqlite3StrAccumAppend(&out, zRawSql, n);
      zRawSql += n;
................................................................................
  Vdbe *p                    /* The VDBE */
){
  int pc=0;                  /* The program counter */
  Op *aOp = p->aOp;          /* Copy of p->aOp */
  Op *pOp;                   /* Current operation */
  int rc = SQLITE_OK;        /* Value to return */
  sqlite3 *db = p->db;       /* The database */
  u8 resetSchemaOnFault = 0; /* Reset schema after an error if true */
  u8 encoding = ENC(db);     /* The database encoding */
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int checkProgress;         /* True if progress callbacks are enabled */
  int nProgressOps = 0;      /* Opcodes executed since progress callback. */
#endif
  Mem *aMem = p->aMem;       /* Copy of p->aMem */
  Mem *pIn1 = 0;             /* 1st input operand */
................................................................................
      int i;
      Mem *pArg;
      sqlite3_context ctx;
      sqlite3_value **apVal;
      int n;
    } ag;
    struct OP_ShiftRight_stack_vars {
      i64 a;

      i64 b;

    } ah;
    struct OP_Ge_stack_vars {
      int res;            /* Result of the comparison of pIn1 against pIn3 */
      char affinity;      /* Affinity to use for comparison */
      u16 flags1;         /* Copy of initial value of pIn1->flags */
      u16 flags3;         /* Copy of initial value of pIn3->flags */
    } ai;
................................................................................
      int iCookie;
    } at;
    struct OP_SetCookie_stack_vars {
      Db *pDb;
    } au;
    struct OP_VerifyCookie_stack_vars {
      int iMeta;

      Btree *pBt;
    } av;
    struct OP_OpenWrite_stack_vars {
      int nField;
      KeyInfo *pKeyInfo;
      int p2;
      int iDb;
................................................................................
      Mem *pRec;
      sqlite3_context ctx;
      sqlite3_value **apVal;
    } cb;
    struct OP_AggFinal_stack_vars {
      Mem *pMem;
    } cc;





    struct OP_JournalMode_stack_vars {
      Btree *pBt;                     /* Btree to change journal mode of */
      Pager *pPager;                  /* Pager associated with pBt */
      int eNew;                       /* New journal mode */
      int eOld;                       /* The old journal mode */
      const char *zFilename;          /* Name of database file for pPager */
    } cd;
    struct OP_IncrVacuum_stack_vars {
      Btree *pBt;
    } ce;
    struct OP_VBegin_stack_vars {
      VTable *pVTab;
    } cf;
    struct OP_VOpen_stack_vars {
      VdbeCursor *pCur;
      sqlite3_vtab_cursor *pVtabCursor;
      sqlite3_vtab *pVtab;
      sqlite3_module *pModule;
    } cg;
    struct OP_VFilter_stack_vars {
      int nArg;
      int iQuery;
      const sqlite3_module *pModule;
      Mem *pQuery;
      Mem *pArgc;
      sqlite3_vtab_cursor *pVtabCursor;
      sqlite3_vtab *pVtab;
      VdbeCursor *pCur;
      int res;
      int i;
      Mem **apArg;
    } ch;
    struct OP_VColumn_stack_vars {
      sqlite3_vtab *pVtab;
      const sqlite3_module *pModule;
      Mem *pDest;
      sqlite3_context sContext;
    } ci;
    struct OP_VNext_stack_vars {
      sqlite3_vtab *pVtab;
      const sqlite3_module *pModule;
      int res;
      VdbeCursor *pCur;
    } cj;
    struct OP_VRename_stack_vars {
      sqlite3_vtab *pVtab;
      Mem *pName;
    } ck;
    struct OP_VUpdate_stack_vars {
      sqlite3_vtab *pVtab;
      sqlite3_module *pModule;
      int nArg;
      int i;
      sqlite_int64 rowid;
      Mem **apArg;
      Mem *pX;
    } cl;
    struct OP_Trace_stack_vars {
      char *zTrace;
    } cm;
  } u;
  /* End automatically generated code
  ********************************************************************/

  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
  sqlite3VdbeMutexArrayEnter(p);
  if( p->rc==SQLITE_NOMEM ){
    /* This happens if a malloc() inside a call to sqlite3_column_text() or
    ** sqlite3_column_text16() failed.  */
    goto no_mem;
  }
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY );
  p->rc = SQLITE_OK;
................................................................................
  pOut = &aMem[pOp->p3];
  u.af.flags = pIn1->flags | pIn2->flags;
  if( (u.af.flags & MEM_Null)!=0 ) goto arithmetic_result_is_null;
  if( (pIn1->flags & pIn2->flags & MEM_Int)==MEM_Int ){
    u.af.iA = pIn1->u.i;
    u.af.iB = pIn2->u.i;
    switch( pOp->opcode ){
      case OP_Add:         u.af.iB += u.af.iA;       break;
      case OP_Subtract:    u.af.iB -= u.af.iA;       break;
      case OP_Multiply:    u.af.iB *= u.af.iA;       break;
      case OP_Divide: {
        if( u.af.iA==0 ) goto arithmetic_result_is_null;
        /* Dividing the largest possible negative 64-bit integer (1<<63) by
        ** -1 returns an integer too large to store in a 64-bit data-type. On
        ** some architectures, the value overflows to (1<<63). On others,
        ** a SIGFPE is issued. The following statement normalizes this
        ** behavior so that all architectures behave as if integer
        ** overflow occurred.
        */
        if( u.af.iA==-1 && u.af.iB==SMALLEST_INT64 ) u.af.iA = 1;
        u.af.iB /= u.af.iA;
        break;
      }
      default: {
        if( u.af.iA==0 ) goto arithmetic_result_is_null;
        if( u.af.iA==-1 ) u.af.iA = 1;
        u.af.iB %= u.af.iA;
        break;
      }
    }
    pOut->u.i = u.af.iB;
    MemSetTypeFlag(pOut, MEM_Int);
  }else{

    u.af.rA = sqlite3VdbeRealValue(pIn1);
    u.af.rB = sqlite3VdbeRealValue(pIn2);
    switch( pOp->opcode ){
      case OP_Add:         u.af.rB += u.af.rA;       break;
      case OP_Subtract:    u.af.rB -= u.af.rA;       break;
      case OP_Multiply:    u.af.rB *= u.af.rA;       break;
      case OP_Divide: {
................................................................................

  /* Copy the result of the function into register P3 */
  sqlite3VdbeChangeEncoding(&u.ag.ctx.s, encoding);
  sqlite3VdbeMemMove(pOut, &u.ag.ctx.s);
  if( sqlite3VdbeMemTooBig(pOut) ){
    goto too_big;
  }









  REGISTER_TRACE(pOp->p3, pOut);
  UPDATE_MAX_BLOBSIZE(pOut);
  break;
}

/* Opcode: BitAnd P1 P2 P3 * *
**
................................................................................
** If either input is NULL, the result is NULL.
*/
case OP_BitAnd:                 /* same as TK_BITAND, in1, in2, out3 */
case OP_BitOr:                  /* same as TK_BITOR, in1, in2, out3 */
case OP_ShiftLeft:              /* same as TK_LSHIFT, in1, in2, out3 */
case OP_ShiftRight: {           /* same as TK_RSHIFT, in1, in2, out3 */
#if 0  /* local variables moved into u.ah */
  i64 a;

  i64 b;

#endif /* local variables moved into u.ah */

  pIn1 = &aMem[pOp->p1];
  pIn2 = &aMem[pOp->p2];
  pOut = &aMem[pOp->p3];
  if( (pIn1->flags | pIn2->flags) & MEM_Null ){
    sqlite3VdbeMemSetNull(pOut);
    break;
  }
  u.ah.a = sqlite3VdbeIntValue(pIn2);
  u.ah.b = sqlite3VdbeIntValue(pIn1);
  switch( pOp->opcode ){
    case OP_BitAnd:      u.ah.a &= u.ah.b;     break;
    case OP_BitOr:       u.ah.a |= u.ah.b;     break;
    case OP_ShiftLeft:   u.ah.a <<= u.ah.b;    break;
    default:  assert( pOp->opcode==OP_ShiftRight );

















                         u.ah.a >>= u.ah.b;    break;


  }



  pOut->u.i = u.ah.a;
  MemSetTypeFlag(pOut, MEM_Int);
  break;
}

/* Opcode: AddImm  P1 P2 * * *
** 
** Add the constant P2 to the value in register P1.
................................................................................
  ** Each type field is a varint representing the serial type of the
  ** corresponding data element (see sqlite3VdbeSerialType()). The
  ** hdr-size field is also a varint which is the offset from the beginning
  ** of the record to data0.
  */
  u.ao.nData = 0;         /* Number of bytes of data space */
  u.ao.nHdr = 0;          /* Number of bytes of header space */
  u.ao.nByte = 0;         /* Data space required for this record */
  u.ao.nZero = 0;         /* Number of zero bytes at the end of the record */
  u.ao.nField = pOp->p1;
  u.ao.zAffinity = pOp->p4.z;
  assert( u.ao.nField>0 && pOp->p2>0 && pOp->p2+u.ao.nField<=p->nMem+1 );
  u.ao.pData0 = &aMem[u.ao.nField];
  u.ao.nField = pOp->p2;
  u.ao.pLast = &u.ao.pData0[u.ao.nField-1];
................................................................................
          rc = sqlite3BtreeSavepoint(db->aDb[u.aq.ii].pBt, u.aq.p1, u.aq.iSavepoint);
          if( rc!=SQLITE_OK ){
            goto abort_due_to_error;
          }
        }
        if( u.aq.p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){
          sqlite3ExpirePreparedStatements(db);
          sqlite3ResetInternalSchema(db, 0);
          db->flags = (db->flags | SQLITE_InternChanges);
        }
      }

      /* Regardless of whether this is a RELEASE or ROLLBACK, destroy all
      ** savepoints nested inside of the savepoint being operated on. */
      while( db->pSavepoint!=u.aq.pSavepoint ){
................................................................................
*/
case OP_Transaction: {
#if 0  /* local variables moved into u.as */
  Btree *pBt;
#endif /* local variables moved into u.as */

  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );
  u.as.pBt = db->aDb[pOp->p1].pBt;

  if( u.as.pBt ){
    rc = sqlite3BtreeBeginTrans(u.as.pBt, pOp->p2);
    if( rc==SQLITE_BUSY ){
      p->pc = pc;
      p->rc = rc = SQLITE_BUSY;
................................................................................
#endif /* local variables moved into u.at */

  u.at.iDb = pOp->p1;
  u.at.iCookie = pOp->p3;
  assert( pOp->p3<SQLITE_N_BTREE_META );
  assert( u.at.iDb>=0 && u.at.iDb<db->nDb );
  assert( db->aDb[u.at.iDb].pBt!=0 );
  assert( (p->btreeMask & (1<<u.at.iDb))!=0 );

  sqlite3BtreeGetMeta(db->aDb[u.at.iDb].pBt, u.at.iCookie, (u32 *)&u.at.iMeta);
  pOut->u.i = u.at.iMeta;
  break;
}

/* Opcode: SetCookie P1 P2 P3 * *
................................................................................
*/
case OP_SetCookie: {       /* in3 */
#if 0  /* local variables moved into u.au */
  Db *pDb;
#endif /* local variables moved into u.au */
  assert( pOp->p2<SQLITE_N_BTREE_META );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );
  u.au.pDb = &db->aDb[pOp->p1];
  assert( u.au.pDb->pBt!=0 );

  pIn3 = &aMem[pOp->p3];
  sqlite3VdbeMemIntegerify(pIn3);
  /* See note about index shifting on OP_ReadCookie */
  rc = sqlite3BtreeUpdateMeta(u.au.pDb->pBt, pOp->p2, (int)pIn3->u.i);
  if( pOp->p2==BTREE_SCHEMA_VERSION ){
    /* When the schema cookie changes, record the new cookie internally */
    u.au.pDb->pSchema->schema_cookie = (int)pIn3->u.i;
................................................................................
    ** schema is changed.  Ticket #1644 */
    sqlite3ExpirePreparedStatements(db);
    p->expired = 0;
  }
  break;
}

/* Opcode: VerifyCookie P1 P2 *
**
** Check the value of global database parameter number 0 (the
** schema version) and make sure it is equal to P2.  


** P1 is the database number which is 0 for the main database file
** and 1 for the file holding temporary tables and some higher number
** for auxiliary databases.
**
** The cookie changes its value whenever the database schema changes.
** This operation is used to detect when that the cookie has changed
** and that the current process needs to reread the schema.
................................................................................
** Either a transaction needs to have been started or an OP_Open needs
** to be executed (to establish a read lock) before this opcode is
** invoked.
*/
case OP_VerifyCookie: {
#if 0  /* local variables moved into u.av */
  int iMeta;

  Btree *pBt;
#endif /* local variables moved into u.av */

  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );

  u.av.pBt = db->aDb[pOp->p1].pBt;
  if( u.av.pBt ){
    sqlite3BtreeGetMeta(u.av.pBt, BTREE_SCHEMA_VERSION, (u32 *)&u.av.iMeta);

  }else{
    u.av.iMeta = 0;
  }
  if( u.av.iMeta!=pOp->p2 ){
    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = sqlite3DbStrDup(db, "database schema has changed");
    /* If the schema-cookie from the database file matches the cookie
    ** stored with the in-memory representation of the schema, do
    ** not reload the schema from the database file.
    **
    ** If virtual-tables are in use, this is not just an optimization.
................................................................................
    ** to be invalidated whenever sqlite3_step() is called from within
    ** a v-table method.
    */
    if( db->aDb[pOp->p1].pSchema->schema_cookie!=u.av.iMeta ){
      sqlite3ResetInternalSchema(db, pOp->p1);
    }

    sqlite3ExpirePreparedStatements(db);
    rc = SQLITE_SCHEMA;
  }
  break;
}

/* Opcode: OpenRead P1 P2 P3 P4 P5
**
................................................................................
  }

  u.aw.nField = 0;
  u.aw.pKeyInfo = 0;
  u.aw.p2 = pOp->p2;
  u.aw.iDb = pOp->p3;
  assert( u.aw.iDb>=0 && u.aw.iDb<db->nDb );
  assert( (p->btreeMask & (1<<u.aw.iDb))!=0 );
  u.aw.pDb = &db->aDb[u.aw.iDb];
  u.aw.pX = u.aw.pDb->pBt;
  assert( u.aw.pX!=0 );
  if( pOp->opcode==OP_OpenWrite ){
    u.aw.wrFlag = 1;

    if( u.aw.pDb->pSchema->file_format < p->minWriteFileFormat ){
      p->minWriteFileFormat = u.aw.pDb->pSchema->file_format;
    }
  }else{
    u.aw.wrFlag = 0;
  }
  if( pOp->p5 ){
................................................................................
    **
    ** The second algorithm is to select a rowid at random and see if
    ** it already exists in the table.  If it does not exist, we have
    ** succeeded.  If the random rowid does exist, we select a new one
    ** and try again, up to 100 times.
    */
    assert( u.be.pC->isTable );
    u.be.cnt = 0;

#ifdef SQLITE_32BIT_ROWID
#   define MAX_ROWID 0x7fffffff
#else
    /* Some compilers complain about constants of the form 0x7fffffffffffffff.
    ** Others complain about 0x7ffffffffffffffffLL.  The following macro seems
    ** to provide the constant while making all compilers happy.
................................................................................
  pOut->flags = MEM_Null;
  if( u.br.iCnt>1 ){
    rc = SQLITE_LOCKED;
    p->errorAction = OE_Abort;
  }else{
    u.br.iDb = pOp->p3;
    assert( u.br.iCnt==1 );
    assert( (p->btreeMask & (1<<u.br.iDb))!=0 );
    rc = sqlite3BtreeDropTable(db->aDb[u.br.iDb].pBt, pOp->p1, &u.br.iMoved);
    pOut->flags = MEM_Int;
    pOut->u.i = u.br.iMoved;
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( rc==SQLITE_OK && u.br.iMoved!=0 ){
      sqlite3RootPageMoved(&db->aDb[u.br.iDb], u.br.iMoved, pOp->p1);


      resetSchemaOnFault = 1;
    }
#endif
  }
  break;
}

/* Opcode: Clear P1 P2 P3
................................................................................
*/
case OP_Clear: {
#if 0  /* local variables moved into u.bs */
  int nChange;
#endif /* local variables moved into u.bs */

  u.bs.nChange = 0;
  assert( (p->btreeMask & (1<<pOp->p2))!=0 );
  rc = sqlite3BtreeClearTable(
      db->aDb[pOp->p2].pBt, pOp->p1, (pOp->p3 ? &u.bs.nChange : 0)
  );
  if( pOp->p3 ){
    p->nChange += u.bs.nChange;
    if( pOp->p3>0 ){
      assert( memIsValid(&aMem[pOp->p3]) );
................................................................................
  int pgno;
  int flags;
  Db *pDb;
#endif /* local variables moved into u.bt */

  u.bt.pgno = 0;
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );
  u.bt.pDb = &db->aDb[pOp->p1];
  assert( u.bt.pDb->pBt!=0 );
  if( pOp->opcode==OP_CreateTable ){
    /* u.bt.flags = BTREE_INTKEY; */
    u.bt.flags = BTREE_INTKEY;
  }else{
    u.bt.flags = BTREE_BLOBKEY;
  }
  rc = sqlite3BtreeCreateTable(u.bt.pDb->pBt, &u.bt.pgno, u.bt.flags);
  pOut->u.i = u.bt.pgno;
  break;
}

/* Opcode: ParseSchema P1 P2 * P4 *
**
** Read and parse all entries from the SQLITE_MASTER table of database P1
** that match the WHERE clause P4.  P2 is the "force" flag.   Always do
** the parsing if P2 is true.  If P2 is false, then this routine is a
** no-op if the schema is not currently loaded.  In other words, if P2
** is false, the SQLITE_MASTER table is only parsed if the rest of the
** schema is already loaded into the symbol table.
**
** This opcode invokes the parser to create a new virtual machine,
** then runs the new virtual machine.  It is thus a re-entrant opcode.
*/
case OP_ParseSchema: {
#if 0  /* local variables moved into u.bu */
  int iDb;
  const char *zMaster;
  char *zSql;
  InitData initData;
#endif /* local variables moved into u.bu */











  u.bu.iDb = pOp->p1;
  assert( u.bu.iDb>=0 && u.bu.iDb<db->nDb );

  /* If pOp->p2 is 0, then this opcode is being executed to read a
  ** single row, for example the row corresponding to a new index
  ** created by this VDBE, from the sqlite_master table. It only
  ** does this if the corresponding in-memory schema is currently
  ** loaded. Otherwise, the new index definition can be loaded along
  ** with the rest of the schema when it is required.
  **
  ** Although the mutex on the BtShared object that corresponds to
  ** database u.bu.iDb (the database containing the sqlite_master table
  ** read by this instruction) is currently held, it is necessary to
  ** obtain the mutexes on all attached databases before checking if
  ** the schema of u.bu.iDb is loaded. This is because, at the start of
  ** the sqlite3_exec() call below, SQLite will invoke
  ** sqlite3BtreeEnterAll(). If all mutexes are not already held, the
  ** u.bu.iDb mutex may be temporarily released to avoid deadlock. If
  ** this happens, then some other thread may delete the in-memory
  ** schema of database u.bu.iDb before the SQL statement runs. The schema
  ** will not be reloaded becuase the db->init.busy flag is set. This
  ** can result in a "no such table: sqlite_master" or "malformed
  ** database schema" error being returned to the user.
  */
  assert( sqlite3BtreeHoldsMutex(db->aDb[u.bu.iDb].pBt) );
  sqlite3BtreeEnterAll(db);
  if( pOp->p2 || DbHasProperty(db, u.bu.iDb, DB_SchemaLoaded) ){

    u.bu.zMaster = SCHEMA_TABLE(u.bu.iDb);
    u.bu.initData.db = db;
    u.bu.initData.iDb = pOp->p1;
    u.bu.initData.pzErrMsg = &p->zErrMsg;
    u.bu.zSql = sqlite3MPrintf(db,
       "SELECT name, rootpage, sql FROM '%q'.%s WHERE %s ORDER BY rowid",
       db->aDb[u.bu.iDb].zName, u.bu.zMaster, pOp->p4.z);
................................................................................
      assert( !db->mallocFailed );
      rc = sqlite3_exec(db, u.bu.zSql, sqlite3InitCallback, &u.bu.initData, 0);
      if( rc==SQLITE_OK ) rc = u.bu.initData.rc;
      sqlite3DbFree(db, u.bu.zSql);
      db->init.busy = 0;
    }
  }
  sqlite3BtreeLeaveAll(db);
  if( rc==SQLITE_NOMEM ){
    goto no_mem;
  }
  break;
}

#if !defined(SQLITE_OMIT_ANALYZE)
................................................................................
  assert( (u.bv.pnErr->flags & (MEM_Str|MEM_Blob))==0 );
  pIn1 = &aMem[pOp->p1];
  for(u.bv.j=0; u.bv.j<u.bv.nRoot; u.bv.j++){
    u.bv.aRoot[u.bv.j] = (int)sqlite3VdbeIntValue(&pIn1[u.bv.j]);
  }
  u.bv.aRoot[u.bv.j] = 0;
  assert( pOp->p5<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p5))!=0 );
  u.bv.z = sqlite3BtreeIntegrityCheck(db->aDb[pOp->p5].pBt, u.bv.aRoot, u.bv.nRoot,
                                 (int)u.bv.pnErr->u.i, &u.bv.nErr);
  sqlite3DbFree(db, u.bv.aRoot);
  u.bv.pnErr->u.i -= u.bv.nErr;
  sqlite3VdbeMemSetNull(pIn1);
  if( u.bv.nErr==0 ){
    assert( u.bv.z==0 );
................................................................................
    u.cb.ctx.pColl = pOp[-1].p4.pColl;
  }
  (u.cb.ctx.pFunc->xStep)(&u.cb.ctx, u.cb.n, u.cb.apVal); /* IMP: R-24505-23230 */
  if( u.cb.ctx.isError ){
    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&u.cb.ctx.s));
    rc = u.cb.ctx.isError;
  }

  sqlite3VdbeMemRelease(&u.cb.ctx.s);

  break;
}

/* Opcode: AggFinal P1 P2 * P4 *
**
** Execute the finalizer function for an aggregate.  P1 is
** the memory location that is the accumulator for the aggregate.
................................................................................
  if( sqlite3VdbeMemTooBig(u.cc.pMem) ){
    goto too_big;
  }
  break;
}

#ifndef SQLITE_OMIT_WAL
/* Opcode: Checkpoint P1 * * * *
**
** Checkpoint database P1. This is a no-op if P1 is not currently in
** WAL mode.






*/
case OP_Checkpoint: {












  rc = sqlite3Checkpoint(db, pOp->p1);







  break;
};  
#endif

#ifndef SQLITE_OMIT_PRAGMA
/* Opcode: JournalMode P1 P2 P3 * P5
**
................................................................................
** operation. No IO is required.
**
** If changing into or out of WAL mode the procedure is more complicated.
**
** Write a string containing the final journal-mode to register P2.
*/
case OP_JournalMode: {    /* out2-prerelease */
#if 0  /* local variables moved into u.cd */
  Btree *pBt;                     /* Btree to change journal mode of */
  Pager *pPager;                  /* Pager associated with pBt */
  int eNew;                       /* New journal mode */
  int eOld;                       /* The old journal mode */
  const char *zFilename;          /* Name of database file for pPager */
#endif /* local variables moved into u.cd */

  u.cd.eNew = pOp->p3;
  assert( u.cd.eNew==PAGER_JOURNALMODE_DELETE
       || u.cd.eNew==PAGER_JOURNALMODE_TRUNCATE
       || u.cd.eNew==PAGER_JOURNALMODE_PERSIST
       || u.cd.eNew==PAGER_JOURNALMODE_OFF
       || u.cd.eNew==PAGER_JOURNALMODE_MEMORY
       || u.cd.eNew==PAGER_JOURNALMODE_WAL
       || u.cd.eNew==PAGER_JOURNALMODE_QUERY
  );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );

  /* This opcode is used in two places: PRAGMA journal_mode and ATTACH.
  ** In PRAGMA journal_mode, the sqlite3VdbeUsesBtree() routine is called
  ** when the statment is prepared and so p->aMutex.nMutex>0.  All mutexes
  ** are already acquired.  But when used in ATTACH, sqlite3VdbeUsesBtree()
  ** is not called when the statement is prepared because it requires the
  ** iDb index of the database as a parameter, and the database has not
  ** yet been attached so that index is unavailable.  We have to wait
  ** until runtime (now) to get the mutex on the newly attached database.
  ** No other mutexes are required by the ATTACH command so this is safe
  ** to do.
  */
  assert( (p->btreeMask & (1<<pOp->p1))!=0 || p->aMutex.nMutex==0 );
  if( p->aMutex.nMutex==0 ){
    /* This occurs right after ATTACH.  Get a mutex on the newly ATTACHed
    ** database. */
    sqlite3VdbeUsesBtree(p, pOp->p1);
    sqlite3VdbeMutexArrayEnter(p);
  }

  u.cd.pBt = db->aDb[pOp->p1].pBt;
  u.cd.pPager = sqlite3BtreePager(u.cd.pBt);
  u.cd.eOld = sqlite3PagerGetJournalMode(u.cd.pPager);
  if( u.cd.eNew==PAGER_JOURNALMODE_QUERY ) u.cd.eNew = u.cd.eOld;
  if( !sqlite3PagerOkToChangeJournalMode(u.cd.pPager) ) u.cd.eNew = u.cd.eOld;

#ifndef SQLITE_OMIT_WAL
  u.cd.zFilename = sqlite3PagerFilename(u.cd.pPager);

  /* Do not allow a transition to journal_mode=WAL for a database
  ** in temporary storage or if the VFS does not support shared memory
  */
  if( u.cd.eNew==PAGER_JOURNALMODE_WAL
   && (u.cd.zFilename[0]==0                         /* Temp file */
       || !sqlite3PagerWalSupported(u.cd.pPager))   /* No shared-memory support */
  ){
    u.cd.eNew = u.cd.eOld;
  }

  if( (u.cd.eNew!=u.cd.eOld)
   && (u.cd.eOld==PAGER_JOURNALMODE_WAL || u.cd.eNew==PAGER_JOURNALMODE_WAL)
  ){
    if( !db->autoCommit || db->activeVdbeCnt>1 ){
      rc = SQLITE_ERROR;
      sqlite3SetString(&p->zErrMsg, db,
          "cannot change %s wal mode from within a transaction",
          (u.cd.eNew==PAGER_JOURNALMODE_WAL ? "into" : "out of")
      );
      break;
    }else{

      if( u.cd.eOld==PAGER_JOURNALMODE_WAL ){
        /* If leaving WAL mode, close the log file. If successful, the call
        ** to PagerCloseWal() checkpoints and deletes the write-ahead-log
        ** file. An EXCLUSIVE lock may still be held on the database file
        ** after a successful return.
        */
        rc = sqlite3PagerCloseWal(u.cd.pPager);
        if( rc==SQLITE_OK ){
          sqlite3PagerSetJournalMode(u.cd.pPager, u.cd.eNew);
        }
      }else if( u.cd.eOld==PAGER_JOURNALMODE_MEMORY ){
        /* Cannot transition directly from MEMORY to WAL.  Use mode OFF
        ** as an intermediate */
        sqlite3PagerSetJournalMode(u.cd.pPager, PAGER_JOURNALMODE_OFF);
      }

      /* Open a transaction on the database file. Regardless of the journal
      ** mode, this transaction always uses a rollback journal.
      */
      assert( sqlite3BtreeIsInTrans(u.cd.pBt)==0 );
      if( rc==SQLITE_OK ){
        rc = sqlite3BtreeSetVersion(u.cd.pBt, (u.cd.eNew==PAGER_JOURNALMODE_WAL ? 2 : 1));
      }
    }
  }
#endif /* ifndef SQLITE_OMIT_WAL */

  if( rc ){
    u.cd.eNew = u.cd.eOld;
  }
  u.cd.eNew = sqlite3PagerSetJournalMode(u.cd.pPager, u.cd.eNew);

  pOut = &aMem[pOp->p2];
  pOut->flags = MEM_Str|MEM_Static|MEM_Term;
  pOut->z = (char *)sqlite3JournalModename(u.cd.eNew);
  pOut->n = sqlite3Strlen30(pOut->z);
  pOut->enc = SQLITE_UTF8;
  sqlite3VdbeChangeEncoding(pOut, encoding);
  break;
};
#endif /* SQLITE_OMIT_PRAGMA */

................................................................................
/* Opcode: IncrVacuum P1 P2 * * *
**
** Perform a single step of the incremental vacuum procedure on
** the P1 database. If the vacuum has finished, jump to instruction
** P2. Otherwise, fall through to the next instruction.
*/
case OP_IncrVacuum: {        /* jump */
#if 0  /* local variables moved into u.ce */
  Btree *pBt;
#endif /* local variables moved into u.ce */

  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );
  u.ce.pBt = db->aDb[pOp->p1].pBt;
  rc = sqlite3BtreeIncrVacuum(u.ce.pBt);
  if( rc==SQLITE_DONE ){
    pc = pOp->p2 - 1;
    rc = SQLITE_OK;
  }
  break;
}
#endif
................................................................................
** used to generate an error message if the lock cannot be obtained.
*/
case OP_TableLock: {
  u8 isWriteLock = (u8)pOp->p3;
  if( isWriteLock || 0==(db->flags&SQLITE_ReadUncommitted) ){
    int p1 = pOp->p1; 
    assert( p1>=0 && p1<db->nDb );
    assert( (p->btreeMask & (1<<p1))!=0 );
    assert( isWriteLock==0 || isWriteLock==1 );
    rc = sqlite3BtreeLockTable(db->aDb[p1].pBt, pOp->p2, isWriteLock);
    if( (rc&0xFF)==SQLITE_LOCKED ){
      const char *z = pOp->p4.z;
      sqlite3SetString(&p->zErrMsg, db, "database table is locked: %s", z);
    }
  }
................................................................................
** xBegin method for that table.
**
** Also, whether or not P4 is set, check that this is not being called from
** within a callback to a virtual table xSync() method. If it is, the error
** code will be set to SQLITE_LOCKED.
*/
case OP_VBegin: {
#if 0  /* local variables moved into u.cf */
  VTable *pVTab;
#endif /* local variables moved into u.cf */
  u.cf.pVTab = pOp->p4.pVtab;
  rc = sqlite3VtabBegin(db, u.cf.pVTab);
  if( u.cf.pVTab ) importVtabErrMsg(p, u.cf.pVTab->pVtab);
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VCreate P1 * * P4 *
**
................................................................................
/* Opcode: VOpen P1 * * P4 *
**
** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
** P1 is a cursor number.  This opcode opens a cursor to the virtual
** table and stores that cursor in P1.
*/
case OP_VOpen: {
#if 0  /* local variables moved into u.cg */
  VdbeCursor *pCur;
  sqlite3_vtab_cursor *pVtabCursor;
  sqlite3_vtab *pVtab;
  sqlite3_module *pModule;
#endif /* local variables moved into u.cg */

  u.cg.pCur = 0;
  u.cg.pVtabCursor = 0;
  u.cg.pVtab = pOp->p4.pVtab->pVtab;
  u.cg.pModule = (sqlite3_module *)u.cg.pVtab->pModule;
  assert(u.cg.pVtab && u.cg.pModule);
  rc = u.cg.pModule->xOpen(u.cg.pVtab, &u.cg.pVtabCursor);
  importVtabErrMsg(p, u.cg.pVtab);
  if( SQLITE_OK==rc ){
    /* Initialize sqlite3_vtab_cursor base class */
    u.cg.pVtabCursor->pVtab = u.cg.pVtab;

    /* Initialise vdbe cursor object */
    u.cg.pCur = allocateCursor(p, pOp->p1, 0, -1, 0);
    if( u.cg.pCur ){
      u.cg.pCur->pVtabCursor = u.cg.pVtabCursor;
      u.cg.pCur->pModule = u.cg.pVtabCursor->pVtab->pModule;
    }else{
      db->mallocFailed = 1;
      u.cg.pModule->xClose(u.cg.pVtabCursor);
    }
  }
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
................................................................................
** xFilter method. Registers P3+2..P3+1+argc are the argc
** additional parameters which are passed to
** xFilter as argv. Register P3+2 becomes argv[0] when passed to xFilter.
**
** A jump is made to P2 if the result set after filtering would be empty.
*/
case OP_VFilter: {   /* jump */
#if 0  /* local variables moved into u.ch */
  int nArg;
  int iQuery;
  const sqlite3_module *pModule;
  Mem *pQuery;
  Mem *pArgc;
  sqlite3_vtab_cursor *pVtabCursor;
  sqlite3_vtab *pVtab;
  VdbeCursor *pCur;
  int res;
  int i;
  Mem **apArg;
#endif /* local variables moved into u.ch */

  u.ch.pQuery = &aMem[pOp->p3];
  u.ch.pArgc = &u.ch.pQuery[1];
  u.ch.pCur = p->apCsr[pOp->p1];
  assert( memIsValid(u.ch.pQuery) );
  REGISTER_TRACE(pOp->p3, u.ch.pQuery);
  assert( u.ch.pCur->pVtabCursor );
  u.ch.pVtabCursor = u.ch.pCur->pVtabCursor;
  u.ch.pVtab = u.ch.pVtabCursor->pVtab;
  u.ch.pModule = u.ch.pVtab->pModule;

  /* Grab the index number and argc parameters */
  assert( (u.ch.pQuery->flags&MEM_Int)!=0 && u.ch.pArgc->flags==MEM_Int );
  u.ch.nArg = (int)u.ch.pArgc->u.i;
  u.ch.iQuery = (int)u.ch.pQuery->u.i;

  /* Invoke the xFilter method */
  {
    u.ch.res = 0;
    u.ch.apArg = p->apArg;
    for(u.ch.i = 0; u.ch.i<u.ch.nArg; u.ch.i++){
      u.ch.apArg[u.ch.i] = &u.ch.pArgc[u.ch.i+1];
      sqlite3VdbeMemStoreType(u.ch.apArg[u.ch.i]);
    }

    p->inVtabMethod = 1;
    rc = u.ch.pModule->xFilter(u.ch.pVtabCursor, u.ch.iQuery, pOp->p4.z, u.ch.nArg, u.ch.apArg);
    p->inVtabMethod = 0;
    importVtabErrMsg(p, u.ch.pVtab);
    if( rc==SQLITE_OK ){
      u.ch.res = u.ch.pModule->xEof(u.ch.pVtabCursor);
    }

    if( u.ch.res ){
      pc = pOp->p2 - 1;
    }
  }
  u.ch.pCur->nullRow = 0;

  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VColumn P1 P2 P3 * *
**
** Store the value of the P2-th column of
** the row of the virtual-table that the 
** P1 cursor is pointing to into register P3.
*/
case OP_VColumn: {
#if 0  /* local variables moved into u.ci */
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;
  Mem *pDest;
  sqlite3_context sContext;
#endif /* local variables moved into u.ci */

  VdbeCursor *pCur = p->apCsr[pOp->p1];
  assert( pCur->pVtabCursor );
  assert( pOp->p3>0 && pOp->p3<=p->nMem );
  u.ci.pDest = &aMem[pOp->p3];
  memAboutToChange(p, u.ci.pDest);
  if( pCur->nullRow ){
    sqlite3VdbeMemSetNull(u.ci.pDest);
    break;
  }
  u.ci.pVtab = pCur->pVtabCursor->pVtab;
  u.ci.pModule = u.ci.pVtab->pModule;
  assert( u.ci.pModule->xColumn );
  memset(&u.ci.sContext, 0, sizeof(u.ci.sContext));

  /* The output cell may already have a buffer allocated. Move
  ** the current contents to u.ci.sContext.s so in case the user-function
  ** can use the already allocated buffer instead of allocating a
  ** new one.
  */
  sqlite3VdbeMemMove(&u.ci.sContext.s, u.ci.pDest);
  MemSetTypeFlag(&u.ci.sContext.s, MEM_Null);

  rc = u.ci.pModule->xColumn(pCur->pVtabCursor, &u.ci.sContext, pOp->p2);
  importVtabErrMsg(p, u.ci.pVtab);
  if( u.ci.sContext.isError ){
    rc = u.ci.sContext.isError;
  }

  /* Copy the result of the function to the P3 register. We
  ** do this regardless of whether or not an error occurred to ensure any
  ** dynamic allocation in u.ci.sContext.s (a Mem struct) is  released.
  */
  sqlite3VdbeChangeEncoding(&u.ci.sContext.s, encoding);
  sqlite3VdbeMemMove(u.ci.pDest, &u.ci.sContext.s);
  REGISTER_TRACE(pOp->p3, u.ci.pDest);
  UPDATE_MAX_BLOBSIZE(u.ci.pDest);

  if( sqlite3VdbeMemTooBig(u.ci.pDest) ){
    goto too_big;
  }
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
................................................................................
/* Opcode: VNext P1 P2 * * *
**
** Advance virtual table P1 to the next row in its result set and
** jump to instruction P2.  Or, if the virtual table has reached
** the end of its result set, then fall through to the next instruction.
*/
case OP_VNext: {   /* jump */
#if 0  /* local variables moved into u.cj */
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;
  int res;
  VdbeCursor *pCur;
#endif /* local variables moved into u.cj */

  u.cj.res = 0;
  u.cj.pCur = p->apCsr[pOp->p1];
  assert( u.cj.pCur->pVtabCursor );
  if( u.cj.pCur->nullRow ){
    break;
  }
  u.cj.pVtab = u.cj.pCur->pVtabCursor->pVtab;
  u.cj.pModule = u.cj.pVtab->pModule;
  assert( u.cj.pModule->xNext );

  /* Invoke the xNext() method of the module. There is no way for the
  ** underlying implementation to return an error if one occurs during
  ** xNext(). Instead, if an error occurs, true is returned (indicating that
  ** data is available) and the error code returned when xColumn or
  ** some other method is next invoked on the save virtual table cursor.
  */
  p->inVtabMethod = 1;
  rc = u.cj.pModule->xNext(u.cj.pCur->pVtabCursor);
  p->inVtabMethod = 0;
  importVtabErrMsg(p, u.cj.pVtab);
  if( rc==SQLITE_OK ){
    u.cj.res = u.cj.pModule->xEof(u.cj.pCur->pVtabCursor);
  }

  if( !u.cj.res ){
    /* If there is data, jump to P2 */
    pc = pOp->p2 - 1;
  }
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

................................................................................
/* Opcode: VRename P1 * * P4 *
**
** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
** This opcode invokes the corresponding xRename method. The value
** in register P1 is passed as the zName argument to the xRename method.
*/
case OP_VRename: {
#if 0  /* local variables moved into u.ck */
  sqlite3_vtab *pVtab;
  Mem *pName;
#endif /* local variables moved into u.ck */

  u.ck.pVtab = pOp->p4.pVtab->pVtab;
  u.ck.pName = &aMem[pOp->p1];
  assert( u.ck.pVtab->pModule->xRename );
  assert( memIsValid(u.ck.pName) );
  REGISTER_TRACE(pOp->p1, u.ck.pName);
  assert( u.ck.pName->flags & MEM_Str );
  rc = u.ck.pVtab->pModule->xRename(u.ck.pVtab, u.ck.pName->z);
  importVtabErrMsg(p, u.ck.pVtab);
  p->expired = 0;

  break;
}
#endif

#ifndef SQLITE_OMIT_VIRTUALTABLE
................................................................................
** a row to delete.
**
** P1 is a boolean flag. If it is set to true and the xUpdate call
** is successful, then the value returned by sqlite3_last_insert_rowid() 
** is set to the value of the rowid for the row just inserted.
*/
case OP_VUpdate: {
#if 0  /* local variables moved into u.cl */
  sqlite3_vtab *pVtab;
  sqlite3_module *pModule;
  int nArg;
  int i;
  sqlite_int64 rowid;
  Mem **apArg;
  Mem *pX;
#endif /* local variables moved into u.cl */

  u.cl.pVtab = pOp->p4.pVtab->pVtab;
  u.cl.pModule = (sqlite3_module *)u.cl.pVtab->pModule;
  u.cl.nArg = pOp->p2;
  assert( pOp->p4type==P4_VTAB );
  if( ALWAYS(u.cl.pModule->xUpdate) ){
    u.cl.apArg = p->apArg;
    u.cl.pX = &aMem[pOp->p3];
    for(u.cl.i=0; u.cl.i<u.cl.nArg; u.cl.i++){
      assert( memIsValid(u.cl.pX) );
      memAboutToChange(p, u.cl.pX);
      sqlite3VdbeMemStoreType(u.cl.pX);
      u.cl.apArg[u.cl.i] = u.cl.pX;
      u.cl.pX++;
    }
    rc = u.cl.pModule->xUpdate(u.cl.pVtab, u.cl.nArg, u.cl.apArg, &u.cl.rowid);
    importVtabErrMsg(p, u.cl.pVtab);
    if( rc==SQLITE_OK && pOp->p1 ){
      assert( u.cl.nArg>1 && u.cl.apArg[0] && (u.cl.apArg[0]->flags&MEM_Null) );
      db->lastRowid = u.cl.rowid;
    }
    p->nChange++;
  }
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

................................................................................
#ifndef SQLITE_OMIT_TRACE
/* Opcode: Trace * * * P4 *
**
** If tracing is enabled (by the sqlite3_trace()) interface, then
** the UTF-8 string contained in P4 is emitted on the trace callback.
*/
case OP_Trace: {
#if 0  /* local variables moved into u.cm */
  char *zTrace;
#endif /* local variables moved into u.cm */

  u.cm.zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql);
  if( u.cm.zTrace ){
    if( db->xTrace ){
      char *z = sqlite3VdbeExpandSql(p, u.cm.zTrace);
      db->xTrace(db->pTraceArg, z);
      sqlite3DbFree(db, z);
    }
#ifdef SQLITE_DEBUG
    if( (db->flags & SQLITE_SqlTrace)!=0 ){
      sqlite3DebugPrintf("SQL-trace: %s\n", u.cm.zTrace);
    }
#endif /* SQLITE_DEBUG */
  }
  break;
}
#endif

................................................................................
  p->rc = rc;
  testcase( sqlite3GlobalConfig.xLog!=0 );
  sqlite3_log(rc, "statement aborts at %d: [%s] %s", 
                   pc, p->zSql, p->zErrMsg);
  sqlite3VdbeHalt(p);
  if( rc==SQLITE_IOERR_NOMEM ) db->mallocFailed = 1;
  rc = SQLITE_ERROR;

  if( resetSchemaOnFault ) sqlite3ResetInternalSchema(db, 0);


  /* This is the only way out of this procedure.  We have to
  ** release the mutexes on btrees that were acquired at the
  ** top. */
vdbe_return:
  sqlite3BtreeMutexArrayLeave(&p->aMutex);
  return rc;

  /* Jump to here if a string or blob larger than SQLITE_MAX_LENGTH
  ** is encountered.
  */
too_big:
  sqlite3SetString(&p->zErrMsg, db, "string or blob too big");
................................................................................
      /* Configure the OP_Transaction */
      sqlite3VdbeChangeP1(v, 0, iDb);
      sqlite3VdbeChangeP2(v, 0, flags);

      /* Configure the OP_VerifyCookie */
      sqlite3VdbeChangeP1(v, 1, iDb);
      sqlite3VdbeChangeP2(v, 1, pTab->pSchema->schema_cookie);


      /* Make sure a mutex is held on the table to be accessed */
      sqlite3VdbeUsesBtree(v, iDb); 

      /* Configure the OP_TableLock instruction */
#ifdef SQLITE_OMIT_SHARED_CACHE
      sqlite3VdbeChangeToNoop(v, 2, 1);
................................................................................
/*
** Return the default collation sequence for the expression pExpr. If
** there is no default collation type, return 0.
*/
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){
  CollSeq *pColl = 0;
  Expr *p = pExpr;
  while( ALWAYS(p) ){
    int op;
    pColl = p->pColl;
    if( pColl ) break;
    op = p->op;
    if( p->pTab!=0 && (
        op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_REGISTER || op==TK_TRIGGER
    )){
................................................................................
  int nExtra = 0;
  int iValue = 0;

  if( pToken ){
    if( op!=TK_INTEGER || pToken->z==0
          || sqlite3GetInt32(pToken->z, &iValue)==0 ){
      nExtra = pToken->n+1;

    }
  }
  pNew = sqlite3DbMallocZero(db, sizeof(Expr)+nExtra);
  if( pNew ){
    pNew->op = (u8)op;
    pNew->iAgg = -1;
    if( pToken ){
................................................................................
}

/*
** Recursively delete an expression tree.
*/
SQLITE_PRIVATE void sqlite3ExprDelete(sqlite3 *db, Expr *p){
  if( p==0 ) return;


  if( !ExprHasAnyProperty(p, EP_TokenOnly) ){
    sqlite3ExprDelete(db, p->pLeft);
    sqlite3ExprDelete(db, p->pRight);
    if( !ExprHasProperty(p, EP_Reduced) && (p->flags2 & EP2_MallocedToken)!=0 ){
      sqlite3DbFree(db, p->u.zToken);
    }
    if( ExprHasProperty(p, EP_xIsSelect) ){
................................................................................
** If the expression p codes a constant integer that is small enough
** to fit in a 32-bit integer, return 1 and put the value of the integer
** in *pValue.  If the expression is not an integer or if it is too big
** to fit in a signed 32-bit integer, return 0 and leave *pValue unchanged.
*/
SQLITE_PRIVATE int sqlite3ExprIsInteger(Expr *p, int *pValue){
  int rc = 0;






  if( p->flags & EP_IntValue ){
    *pValue = p->u.iValue;
    return 1;
  }
  switch( p->op ){
    case TK_INTEGER: {
      rc = sqlite3GetInt32(p->u.zToken, pValue);
      assert( rc==0 );
      break;
    }
    case TK_UPLUS: {
      rc = sqlite3ExprIsInteger(p->pLeft, pValue);
      break;
    }
    case TK_UMINUS: {
      int v;
      if( sqlite3ExprIsInteger(p->pLeft, &v) ){
................................................................................
        *pValue = -v;
        rc = 1;
      }
      break;
    }
    default: break;
  }
  if( rc ){
    assert( ExprHasAnyProperty(p, EP_Reduced|EP_TokenOnly)
               || (p->flags2 & EP2_MallocedToken)==0 );
    p->op = TK_INTEGER;
    p->flags |= EP_IntValue;
    p->u.iValue = *pValue;
  }
  return rc;
}

/*
** Return FALSE if there is no chance that the expression can be NULL.
**
** If the expression might be NULL or if the expression is too complex
................................................................................
**
** Expr.u.zToken is always UTF8 and zero-terminated.
*/
static void codeInteger(Parse *pParse, Expr *pExpr, int negFlag, int iMem){
  Vdbe *v = pParse->pVdbe;
  if( pExpr->flags & EP_IntValue ){
    int i = pExpr->u.iValue;

    if( negFlag ) i = -i;
    sqlite3VdbeAddOp2(v, OP_Integer, i, iMem);
  }else{
    int c;
    i64 value;
    const char *z = pExpr->u.zToken;
    assert( z!=0 );
    c = sqlite3Atoi64(z, &value, sqlite3Strlen30(z), SQLITE_UTF8);
    if( c==0 || (c==2 && negFlag) ){
      char *zV;
      if( negFlag ){ value = -value; }
      zV = dup8bytes(v, (char*)&value);
      sqlite3VdbeAddOp4(v, OP_Int64, 0, iMem, 0, zV, P4_INT64);
    }else{
#ifdef SQLITE_OMIT_FLOATING_POINT
      sqlite3ErrorMsg(pParse, "oversized integer: %s%s", negFlag ? "-" : "", z);
#else
      codeReal(v, z, negFlag, iMem);
................................................................................
#endif
    case TK_VARIABLE: {
      assert( !ExprHasProperty(pExpr, EP_IntValue) );
      assert( pExpr->u.zToken!=0 );
      assert( pExpr->u.zToken[0]!=0 );
      sqlite3VdbeAddOp2(v, OP_Variable, pExpr->iColumn, target);
      if( pExpr->u.zToken[1]!=0 ){
        sqlite3VdbeChangeP4(v, -1, pExpr->u.zToken, 0);
      }
      break;
    }
    case TK_REGISTER: {
      inReg = pExpr->iTable;
      break;
    }
................................................................................
      break;
    }
    case TK_BETWEEN: {
      testcase( jumpIfNull==0 );
      exprCodeBetween(pParse, pExpr, dest, 1, jumpIfNull);
      break;
    }

    case TK_IN: {
      int destIfFalse = sqlite3VdbeMakeLabel(v);
      int destIfNull = jumpIfNull ? dest : destIfFalse;
      sqlite3ExprCodeIN(pParse, pExpr, destIfFalse, destIfNull);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, dest);
      sqlite3VdbeResolveLabel(v, destIfFalse);
      break;
    }

    default: {
      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
      sqlite3VdbeAddOp3(v, OP_If, r1, dest, jumpIfNull!=0);
      testcase( regFree1==0 );
      testcase( jumpIfNull==0 );
      break;
    }
................................................................................
      break;
    }
    case TK_BETWEEN: {
      testcase( jumpIfNull==0 );
      exprCodeBetween(pParse, pExpr, dest, 0, jumpIfNull);
      break;
    }

    case TK_IN: {
      if( jumpIfNull ){
        sqlite3ExprCodeIN(pParse, pExpr, dest, dest);
      }else{
        int destIfNull = sqlite3VdbeMakeLabel(v);
        sqlite3ExprCodeIN(pParse, pExpr, dest, destIfNull);
        sqlite3VdbeResolveLabel(v, destIfNull);
      }
      break;
    }

    default: {
      r1 = sqlite3ExprCodeTemp(pParse, pExpr, &regFree1);
      sqlite3VdbeAddOp3(v, OP_IfNot, r1, dest, jumpIfNull!=0);
      testcase( regFree1==0 );
      testcase( jumpIfNull==0 );
      break;
    }
................................................................................
  ** triggers. Don't use IN(...) in case SQLITE_OMIT_SUBQUERY is defined. 
  */
  if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
    sqlite3VdbeAddOp4(v, OP_ParseSchema, 1, 0, 0, zWhere, P4_DYNAMIC);
  }
#endif
}

















/*
** Generate code to implement the "ALTER TABLE xxx RENAME TO yyy" 
** command. 
*/
SQLITE_PRIVATE void sqlite3AlterRenameTable(
  Parse *pParse,            /* Parser context. */
................................................................................
        "there is already another table or index with this name: %s", zName);
    goto exit_rename_table;
  }

  /* Make sure it is not a system table being altered, or a reserved name
  ** that the table is being renamed to.
  */
  if( sqlite3Strlen30(pTab->zName)>6 
   && 0==sqlite3StrNICmp(pTab->zName, "sqlite_", 7)
  ){
    sqlite3ErrorMsg(pParse, "table %s may not be altered", pTab->zName);
    goto exit_rename_table;
  }
  if( SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
    goto exit_rename_table;
  }

#ifndef SQLITE_OMIT_VIEW
  if( pTab->pSelect ){
    sqlite3ErrorMsg(pParse, "view %s may not be altered", pTab->zName);
    goto exit_rename_table;
  }
................................................................................
#endif

  /* Make sure this is not an attempt to ALTER a view. */
  if( pTab->pSelect ){
    sqlite3ErrorMsg(pParse, "Cannot add a column to a view");
    goto exit_begin_add_column;
  }




  assert( pTab->addColOffset>0 );
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);

  /* Put a copy of the Table struct in Parse.pNewTable for the
  ** sqlite3AddColumn() function and friends to modify.  But modify
  ** the name by adding an "sqlite_altertab_" prefix.  By adding this
................................................................................
** with the named table are deleted. If zWhere==0, then code is generated
** to delete all stat table entries.
*/
static void openStatTable(
  Parse *pParse,          /* Parsing context */
  int iDb,                /* The database we are looking in */
  int iStatCur,           /* Open the sqlite_stat1 table on this cursor */
  const char *zWhere      /* Delete entries associated with this table */

){
  static const struct {
    const char *zName;
    const char *zCols;
  } aTable[] = {
    { "sqlite_stat1", "tbl,idx,stat" },
#ifdef SQLITE_ENABLE_STAT2
................................................................................
      /* The table already exists. If zWhere is not NULL, delete all entries 
      ** associated with the table zWhere. If zWhere is NULL, delete the
      ** entire contents of the table. */
      aRoot[i] = pStat->tnum;
      sqlite3TableLock(pParse, iDb, aRoot[i], 1, zTab);
      if( zWhere ){
        sqlite3NestedParse(pParse,
           "DELETE FROM %Q.%s WHERE tbl=%Q", pDb->zName, zTab, zWhere
        );
      }else{
        /* The sqlite_stat[12] table already exists.  Delete all rows. */
        sqlite3VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
      }
    }
  }
................................................................................
/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
  Table *pTab,     /* Table whose indices are to be analyzed */

  int iStatCur,    /* Index of VdbeCursor that writes the sqlite_stat1 table */
  int iMem         /* Available memory locations begin here */
){
  sqlite3 *db = pParse->db;    /* Database handle */
  Index *pIdx;                 /* An index to being analyzed */
  int iIdxCur;                 /* Cursor open on index being analyzed */
  Vdbe *v;                     /* The virtual machine being built up */
  int i;                       /* Loop counter */
  int topOfLoop;               /* The top of the loop */
  int endOfLoop;               /* The end of the loop */
  int addr = 0;                /* The address of an instruction */
  int jZeroRows = 0;           /* Jump from here if number of rows is zero */
  int iDb;                     /* Index of database containing pTab */
  int regTabname = iMem++;     /* Register containing table name */
  int regIdxname = iMem++;     /* Register containing index name */
  int regSampleno = iMem++;    /* Register containing next sample number */
  int regCol = iMem++;         /* Content of a column analyzed table */
  int regRec = iMem++;         /* Register holding completed record */
  int regTemp = iMem++;        /* Temporary use register */
  int regRowid = iMem++;       /* Rowid for the inserted record */

#ifdef SQLITE_ENABLE_STAT2

  int regTemp2 = iMem++;       /* Temporary use register */
  int regSamplerecno = iMem++; /* Index of next sample to record */
  int regRecno = iMem++;       /* Current sample index */
  int regLast = iMem++;        /* Index of last sample to record */
  int regFirst = iMem++;       /* Index of first sample to record */
#endif

................................................................................
  if( memcmp(pTab->zName, "sqlite_", 7)==0 ){
    /* Do not gather statistics on system tables */
    return;
  }
  assert( sqlite3BtreeHoldsAllMutexes(db) );
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  assert( iDb>=0 );

#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
      db->aDb[iDb].zName ) ){
    return;
  }
#endif

  /* Establish a read-lock on the table at the shared-cache level. */
  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

  iIdxCur = pParse->nTab++;
  sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    int nCol = pIdx->nColumn;
    KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);




    if( iMem+1+(nCol*2)>pParse->nMem ){
      pParse->nMem = iMem+1+(nCol*2);
    }

    /* Open a cursor to the index to be analyzed. */
    assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
    sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb,
................................................................................
    **        I = (K+D-1)/D
    **
    ** If K==0 then no entry is made into the sqlite_stat1 table.  
    ** If K>0 then it is always the case the D>0 so division by zero
    ** is never possible.
    */
    sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regSampleno);
    if( jZeroRows==0 ){
      jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);
    }
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
      sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);
      sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
................................................................................
  ** containing NULL as the index name and the row count as the content.
  */
  if( pTab->pIndex==0 ){
    sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
    VdbeComment((v, "%s", pTab->zName));
    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regSampleno);
    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);

  }else{
    assert( jZeroRows>0 );
    addr = sqlite3VdbeAddOp0(v, OP_Goto);
    sqlite3VdbeJumpHere(v, jZeroRows);

  }
  sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
  sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
  sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
  sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
  sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
  if( pParse->nMem<regRec ) pParse->nMem = regRec;
  if( jZeroRows ){
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*
** Generate code that will cause the most recent index analysis to
** be loaded into internal hash tables where is can be used.
*/
static void loadAnalysis(Parse *pParse, int iDb){
................................................................................
  HashElem *k;
  int iStatCur;
  int iMem;

  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab;
  pParse->nTab += 2;
  openStatTable(pParse, iDb, iStatCur, 0);
  iMem = pParse->nMem+1;

  for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
    Table *pTab = (Table*)sqliteHashData(k);
    analyzeOneTable(pParse, pTab, iStatCur, iMem);
  }
  loadAnalysis(pParse, iDb);
}

/*
** Generate code that will do an analysis of a single table in
** a database.

*/
static void analyzeTable(Parse *pParse, Table *pTab){
  int iDb;
  int iStatCur;

  assert( pTab!=0 );
  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  sqlite3BeginWriteOperation(pParse, 0, iDb);
  iStatCur = pParse->nTab;
  pParse->nTab += 2;



  openStatTable(pParse, iDb, iStatCur, pTab->zName);

  analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem+1);
  loadAnalysis(pParse, iDb);
}

/*
** Generate code for the ANALYZE command.  The parser calls this routine
** when it recognizes an ANALYZE command.
**
................................................................................
*/
SQLITE_PRIVATE void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){
  sqlite3 *db = pParse->db;
  int iDb;
  int i;
  char *z, *zDb;
  Table *pTab;

  Token *pTableName;

  /* Read the database schema. If an error occurs, leave an error message
  ** and code in pParse and return NULL. */
  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
    return;
................................................................................
    /* Form 2:  Analyze the database or table named */
    iDb = sqlite3FindDb(db, pName1);
    if( iDb>=0 ){
      analyzeDatabase(pParse, iDb);
    }else{
      z = sqlite3NameFromToken(db, pName1);
      if( z ){


        pTab = sqlite3LocateTable(pParse, 0, z, 0);
        sqlite3DbFree(db, z);
        if( pTab ){
          analyzeTable(pParse, pTab);
        }

      }
    }
  }else{
    /* Form 3: Analyze the fully qualified table name */
    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
    if( iDb>=0 ){
      zDb = db->aDb[iDb].zName;
      z = sqlite3NameFromToken(db, pTableName);
      if( z ){


        pTab = sqlite3LocateTable(pParse, 0, z, zDb);
        sqlite3DbFree(db, z);
        if( pTab ){
          analyzeTable(pParse, pTab);
        }

      }
    }   
  }
}

/*
** Used to pass information from the analyzer reader through to the
................................................................................
      v = v*10 + c - '0';
      z++;
    }
    if( i==0 ) pTable->nRowEst = v;
    if( pIndex==0 ) break;
    pIndex->aiRowEst[i] = v;
    if( *z==' ' ) z++;




  }
  return 0;
}

/*
** If the Index.aSample variable is not NULL, delete the aSample[] array
** and its contents.
................................................................................
  analysisInfo sInfo;
  HashElem *i;
  char *zSql;
  int rc;

  assert( iDb>=0 && iDb<db->nDb );
  assert( db->aDb[iDb].pBt!=0 );
  assert( sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );

  /* Clear any prior statistics */

  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
    Index *pIdx = sqliteHashData(i);
    sqlite3DefaultRowEst(pIdx);
    sqlite3DeleteIndexSamples(db, pIdx);
    pIdx->aSample = 0;
  }

................................................................................
        zKey = (char *)sqlite3_value_blob(argv[2]);
        rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
        break;

      case SQLITE_NULL:
        /* No key specified.  Use the key from the main database */
        sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);

        rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);

        break;
    }
  }
#endif

  /* If the file was opened successfully, read the schema for the new database.
  ** If this fails, or if opening the file failed, then close the file and 
................................................................................
    int iDb = db->nDb - 1;
    assert( iDb>=2 );
    if( db->aDb[iDb].pBt ){
      sqlite3BtreeClose(db->aDb[iDb].pBt);
      db->aDb[iDb].pBt = 0;
      db->aDb[iDb].pSchema = 0;
    }
    sqlite3ResetInternalSchema(db, 0);
    db->nDb = iDb;
    if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
      db->mallocFailed = 1;
      sqlite3DbFree(db, zErrDyn);
      zErrDyn = sqlite3MPrintf(db, "out of memory");
    }else if( zErrDyn==0 ){
      zErrDyn = sqlite3MPrintf(db, "unable to open database: %s", zFile);
................................................................................
    sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
    goto detach_error;
  }

  sqlite3BtreeClose(pDb->pBt);
  pDb->pBt = 0;
  pDb->pSchema = 0;
  sqlite3ResetInternalSchema(db, 0);
  return;

detach_error:
  sqlite3_result_error(context, zErr, -1);
}

/*
................................................................................
  ){
    pParse->nErr++;
    goto attach_end;
  }

#ifndef SQLITE_OMIT_AUTHORIZATION
  if( pAuthArg ){


    char *zAuthArg = pAuthArg->u.zToken;

    if( NEVER(zAuthArg==0) ){
      goto attach_end;
    }
    rc = sqlite3AuthCheck(pParse, type, zAuthArg, 0, 0);
    if(rc!=SQLITE_OK ){
      goto attach_end;
    }
  }
#endif /* SQLITE_OMIT_AUTHORIZATION */
................................................................................
    /* The cookie mask contains one bit for each database file open.
    ** (Bit 0 is for main, bit 1 is for temp, and so forth.)  Bits are
    ** set for each database that is used.  Generate code to start a
    ** transaction on each used database and to verify the schema cookie
    ** on each used database.
    */
    if( pParse->cookieGoto>0 ){
      u32 mask;
      int iDb;
      sqlite3VdbeJumpHere(v, pParse->cookieGoto-1);
      for(iDb=0, mask=1; iDb<db->nDb; mask<<=1, iDb++){
        if( (mask & pParse->cookieMask)==0 ) continue;
        sqlite3VdbeUsesBtree(v, iDb);
        sqlite3VdbeAddOp2(v,OP_Transaction, iDb, (mask & pParse->writeMask)!=0);
        if( db->init.busy==0 ){


          sqlite3VdbeAddOp2(v,OP_VerifyCookie, iDb, pParse->cookieValue[iDb]);

        }
      }
#ifndef SQLITE_OMIT_VIRTUALTABLE
      {
        int i;
        for(i=0; i<pParse->nVtabLock; i++){
          char *vtab = (char *)sqlite3GetVTable(db, pParse->apVtabLock[i]);
................................................................................
*/
SQLITE_PRIVATE Table *sqlite3FindTable(sqlite3 *db, const char *zName, const char *zDatabase){
  Table *p = 0;
  int i;
  int nName;
  assert( zName!=0 );
  nName = sqlite3Strlen30(zName);


  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */
    if( zDatabase!=0 && sqlite3StrICmp(zDatabase, db->aDb[j].zName) ) continue;

    p = sqlite3HashFind(&db->aDb[j].pSchema->tblHash, zName, nName);
    if( p ) break;
  }
  return p;
}

/*
................................................................................
** TEMP first, then MAIN, then any auxiliary databases added
** using the ATTACH command.
*/
SQLITE_PRIVATE Index *sqlite3FindIndex(sqlite3 *db, const char *zName, const char *zDb){
  Index *p = 0;
  int i;
  int nName = sqlite3Strlen30(zName);


  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    Schema *pSchema = db->aDb[j].pSchema;
    assert( pSchema );
    if( zDb && sqlite3StrICmp(zDb, db->aDb[j].zName) ) continue;

    p = sqlite3HashFind(&pSchema->idxHash, zName, nName);
    if( p ) break;
  }
  return p;
}

/*
................................................................................
** unlike that index from its Table then remove the index from
** the index hash table and free all memory structures associated
** with the index.
*/
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteIndex(sqlite3 *db, int iDb, const char *zIdxName){
  Index *pIndex;
  int len;
  Hash *pHash = &db->aDb[iDb].pSchema->idxHash;



  len = sqlite3Strlen30(zIdxName);
  pIndex = sqlite3HashInsert(pHash, zIdxName, len, 0);
  if( pIndex ){

    if( pIndex->pTable->pIndex==pIndex ){
      pIndex->pTable->pIndex = pIndex->pNext;
    }else{
      Index *p;
      /* Justification of ALWAYS();  The index must be on the list of
      ** indices. */
      p = pIndex->pTable->pIndex;
................................................................................
/*
** Erase all schema information from the in-memory hash tables of
** a single database.  This routine is called to reclaim memory
** before the database closes.  It is also called during a rollback
** if there were schema changes during the transaction or if a
** schema-cookie mismatch occurs.
**
** If iDb==0 then reset the internal schema tables for all database
** files.  If iDb>=1 then reset the internal schema for only the
** single file indicated.
*/
SQLITE_PRIVATE void sqlite3ResetInternalSchema(sqlite3 *db, int iDb){
  int i, j;
  assert( iDb>=0 && iDb<db->nDb );

  if( iDb==0 ){
    sqlite3BtreeEnterAll(db);




  }















  for(i=iDb; i<db->nDb; i++){
    Db *pDb = &db->aDb[i];
    if( pDb->pSchema ){
      assert(i==1 || (pDb->pBt && sqlite3BtreeHoldsMutex(pDb->pBt)));
      sqlite3SchemaFree(pDb->pSchema);
    }
    if( iDb>0 ) return;
  }
  assert( iDb==0 );
  db->flags &= ~SQLITE_InternChanges;
  sqlite3VtabUnlockList(db);
  sqlite3BtreeLeaveAll(db);

  /* If one or more of the auxiliary database files has been closed,
  ** then remove them from the auxiliary database list.  We take the
  ** opportunity to do this here since we have just deleted all of the
................................................................................
    pNext = pIndex->pNext;
    assert( pIndex->pSchema==pTable->pSchema );
    if( !db || db->pnBytesFreed==0 ){
      char *zName = pIndex->zName; 
      TESTONLY ( Index *pOld = ) sqlite3HashInsert(
	  &pIndex->pSchema->idxHash, zName, sqlite3Strlen30(zName), 0
      );

      assert( pOld==pIndex || pOld==0 );
    }
    freeIndex(db, pIndex);
  }

  /* Delete any foreign keys attached to this table. */
  sqlite3FkDelete(db, pTable);
................................................................................
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTable(sqlite3 *db, int iDb, const char *zTabName){
  Table *p;
  Db *pDb;

  assert( db!=0 );
  assert( iDb>=0 && iDb<db->nDb );
  assert( zTabName );

  testcase( zTabName[0]==0 );  /* Zero-length table names are allowed */
  pDb = &db->aDb[iDb];
  p = sqlite3HashInsert(&pDb->pSchema->tblHash, zTabName,
                        sqlite3Strlen30(zTabName),0);
  sqlite3DeleteTable(db, p);
  db->flags |= SQLITE_InternChanges;
}
................................................................................
    if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
      goto begin_table_error;
    }
    pTable = sqlite3FindTable(db, zName, zDb);
    if( pTable ){
      if( !noErr ){
        sqlite3ErrorMsg(pParse, "table %T already exists", pName);



      }
      goto begin_table_error;
    }
    if( sqlite3FindIndex(db, zName, zDb)!=0 ){
      sqlite3ErrorMsg(pParse, "there is already an index named %s", zName);
      goto begin_table_error;
    }
................................................................................

  /* If this is the magic sqlite_sequence table used by autoincrement,
  ** then record a pointer to this table in the main database structure
  ** so that INSERT can find the table easily.
  */
#ifndef SQLITE_OMIT_AUTOINCREMENT
  if( !pParse->nested && strcmp(zName, "sqlite_sequence")==0 ){

    pTable->pSchema->pSeqTab = pTable;
  }
#endif

  /* Begin generating the code that will insert the table record into
  ** the SQLITE_MASTER table.  Note in particular that we must go ahead
  ** and allocate the record number for the table entry now.  Before any
................................................................................
** and the probability of hitting the same cookie value is only
** 1 chance in 2^32.  So we're safe enough.
*/
SQLITE_PRIVATE void sqlite3ChangeCookie(Parse *pParse, int iDb){
  int r1 = sqlite3GetTempReg(pParse);
  sqlite3 *db = pParse->db;
  Vdbe *v = pParse->pVdbe;

  sqlite3VdbeAddOp2(v, OP_Integer, db->aDb[iDb].pSchema->schema_cookie+1, r1);
  sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_SCHEMA_VERSION, r1);
  sqlite3ReleaseTempReg(pParse, r1);
}

/*
** Measure the number of characters needed to output the given
................................................................................
    const char *zType;

    sqlite3_snprintf(n-k, &zStmt[k], zSep);
    k += sqlite3Strlen30(&zStmt[k]);
    zSep = zSep2;
    identPut(zStmt, &k, pCol->zName);
    assert( pCol->affinity-SQLITE_AFF_TEXT >= 0 );
    assert( pCol->affinity-SQLITE_AFF_TEXT < sizeof(azType)/sizeof(azType[0]) );
    testcase( pCol->affinity==SQLITE_AFF_TEXT );
    testcase( pCol->affinity==SQLITE_AFF_NONE );
    testcase( pCol->affinity==SQLITE_AFF_NUMERIC );
    testcase( pCol->affinity==SQLITE_AFF_INTEGER );
    testcase( pCol->affinity==SQLITE_AFF_REAL );
    
    zType = azType[pCol->affinity - SQLITE_AFF_TEXT];
................................................................................

#ifndef SQLITE_OMIT_AUTOINCREMENT
    /* Check to see if we need to create an sqlite_sequence table for
    ** keeping track of autoincrement keys.
    */
    if( p->tabFlags & TF_Autoincrement ){
      Db *pDb = &db->aDb[iDb];

      if( pDb->pSchema->pSeqTab==0 ){
        sqlite3NestedParse(pParse,
          "CREATE TABLE %Q.sqlite_sequence(name,seq)",
          pDb->zName
        );
      }
    }
................................................................................


  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy ){
    Table *pOld;
    Schema *pSchema = p->pSchema;

    pOld = sqlite3HashInsert(&pSchema->tblHash, p->zName,
                             sqlite3Strlen30(p->zName),p);
    if( pOld ){
      assert( p==pOld );  /* Malloc must have failed inside HashInsert() */
      db->mallocFailed = 1;
      return;
    }
................................................................................
    if( pSelTab ){
      assert( pTable->aCol==0 );
      pTable->nCol = pSelTab->nCol;
      pTable->aCol = pSelTab->aCol;
      pSelTab->nCol = 0;
      pSelTab->aCol = 0;
      sqlite3DeleteTable(db, pSelTab);

      pTable->pSchema->flags |= DB_UnresetViews;
    }else{
      pTable->nCol = 0;
      nErr++;
    }
    sqlite3SelectDelete(db, pSel);
  } else {
................................................................................

#ifndef SQLITE_OMIT_VIEW
/*
** Clear the column names from every VIEW in database idx.
*/
static void sqliteViewResetAll(sqlite3 *db, int idx){
  HashElem *i;

  if( !DbHasProperty(db, idx, DB_UnresetViews) ) return;
  for(i=sqliteHashFirst(&db->aDb[idx].pSchema->tblHash); i;i=sqliteHashNext(i)){
    Table *pTab = sqliteHashData(i);
    if( pTab->pSelect ){
      sqliteDeleteColumnNames(db, pTab);
      pTab->aCol = 0;
      pTab->nCol = 0;
................................................................................
** because the first match might be for one of the deleted indices
** or tables and not the table/index that is actually being moved.
** We must continue looping until all tables and indices with
** rootpage==iFrom have been converted to have a rootpage of iTo
** in order to be certain that we got the right one.
*/
#ifndef SQLITE_OMIT_AUTOVACUUM
SQLITE_PRIVATE void sqlite3RootPageMoved(Db *pDb, int iFrom, int iTo){
  HashElem *pElem;
  Hash *pHash;




  pHash = &pDb->pSchema->tblHash;
  for(pElem=sqliteHashFirst(pHash); pElem; pElem=sqliteHashNext(pElem)){
    Table *pTab = sqliteHashData(pElem);
    if( pTab->tnum==iFrom ){
      pTab->tnum = iTo;
    }
  }
................................................................................
  assert( pName->nSrc==1 );
  if( noErr ) db->suppressErr++;
  pTab = sqlite3LocateTable(pParse, isView, 
                            pName->a[0].zName, pName->a[0].zDatabase);
  if( noErr ) db->suppressErr--;

  if( pTab==0 ){

    goto exit_drop_table;
  }
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  assert( iDb>=0 && iDb<db->nDb );

  /* If pTab is a virtual table, call ViewGetColumnNames() to ensure
  ** it is initialized.
................................................................................
      z += n+1;
    }
  }
  pFKey->isDeferred = 0;
  pFKey->aAction[0] = (u8)(flags & 0xff);            /* ON DELETE action */
  pFKey->aAction[1] = (u8)((flags >> 8 ) & 0xff);    /* ON UPDATE action */


  pNextTo = (FKey *)sqlite3HashInsert(&p->pSchema->fkeyHash, 
      pFKey->zTo, sqlite3Strlen30(pFKey->zTo), (void *)pFKey
  );
  if( pNextTo==pFKey ){
    db->mallocFailed = 1;
    goto fk_end;
  }
................................................................................
        sqlite3ErrorMsg(pParse, "there is already a table named %s", zName);
        goto exit_create_index;
      }
    }
    if( sqlite3FindIndex(db, zName, pDb->zName)!=0 ){
      if( !ifNotExist ){
        sqlite3ErrorMsg(pParse, "index %s already exists", zName);



      }
      goto exit_create_index;
    }
  }else{
    int n;
    Index *pLoop;
    for(pLoop=pTab->pIndex, n=1; pLoop; pLoop=pLoop->pNext, n++){}
................................................................................
  zExtra = (char *)(&pIndex->zName[nName+1]);
  memcpy(pIndex->zName, zName, nName+1);
  pIndex->pTable = pTab;
  pIndex->nColumn = pList->nExpr;
  pIndex->onError = (u8)onError;
  pIndex->autoIndex = (u8)(pName==0);
  pIndex->pSchema = db->aDb[iDb].pSchema;


  /* Check to see if we should honor DESC requests on index columns
  */
  if( pDb->pSchema->file_format>=4 ){
    sortOrderMask = -1;   /* Honor DESC */
  }else{
    sortOrderMask = 0;    /* Ignore DESC */
................................................................................
  }

  /* Link the new Index structure to its table and to the other
  ** in-memory database structures. 
  */
  if( db->init.busy ){
    Index *p;

    p = sqlite3HashInsert(&pIndex->pSchema->idxHash, 
                          pIndex->zName, sqlite3Strlen30(pIndex->zName),
                          pIndex);
    if( p ){
      assert( p==pIndex );  /* Malloc must have failed */
      db->mallocFailed = 1;
      goto exit_create_index;
................................................................................
  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
    goto exit_drop_index;
  }
  pIndex = sqlite3FindIndex(db, pName->a[0].zName, pName->a[0].zDatabase);
  if( pIndex==0 ){
    if( !ifExists ){
      sqlite3ErrorMsg(pParse, "no such index: %S", pName, 0);


    }
    pParse->checkSchema = 1;
    goto exit_drop_index;
  }
  if( pIndex->autoIndex ){
    sqlite3ErrorMsg(pParse, "index associated with UNIQUE "
      "or PRIMARY KEY constraint cannot be dropped", 0);
................................................................................
  if( pToplevel->cookieGoto==0 ){
    Vdbe *v = sqlite3GetVdbe(pToplevel);
    if( v==0 ) return;  /* This only happens if there was a prior error */
    pToplevel->cookieGoto = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0)+1;
  }
  if( iDb>=0 ){
    sqlite3 *db = pToplevel->db;
    int mask;

    assert( iDb<db->nDb );
    assert( db->aDb[iDb].pBt!=0 || iDb==1 );
    assert( iDb<SQLITE_MAX_ATTACHED+2 );

    mask = 1<<iDb;
    if( (pToplevel->cookieMask & mask)==0 ){
      pToplevel->cookieMask |= mask;
      pToplevel->cookieValue[iDb] = db->aDb[iDb].pSchema->schema_cookie;
      if( !OMIT_TEMPDB && iDb==1 ){
        sqlite3OpenTempDatabase(pToplevel);
      }
    }
  }
}
















/*
** Generate VDBE code that prepares for doing an operation that
** might change the database.
**
** This routine starts a new transaction if we are not already within
** a transaction.  If we are already within a transaction, then a checkpoint
................................................................................
** rollback the whole transaction.  For operations where all constraints
** can be checked before any changes are made to the database, it is never
** necessary to undo a write and the checkpoint should not be set.
*/
SQLITE_PRIVATE void sqlite3BeginWriteOperation(Parse *pParse, int setStatement, int iDb){
  Parse *pToplevel = sqlite3ParseToplevel(pParse);
  sqlite3CodeVerifySchema(pParse, iDb);
  pToplevel->writeMask |= 1<<iDb;
  pToplevel->isMultiWrite |= setStatement;
}

/*
** Indicate that the statement currently under construction might write
** more than one entry (example: deleting one row then inserting another,
** inserting multiple rows in a table, or inserting a row and index entries.)
................................................................................
static void reindexDatabases(Parse *pParse, char const *zColl){
  Db *pDb;                    /* A single database */
  int iDb;                    /* The database index number */
  sqlite3 *db = pParse->db;   /* The database connection */
  HashElem *k;                /* For looping over tables in pDb */
  Table *pTab;                /* A table in the database */


  for(iDb=0, pDb=db->aDb; iDb<db->nDb; iDb++, pDb++){
    assert( pDb!=0 );
    for(k=sqliteHashFirst(&pDb->pSchema->tblHash);  k; k=sqliteHashNext(k)){
      pTab = (Table*)sqliteHashData(k);
      reindexTable(pParse, pTab, zColl);
    }
  }
................................................................................
  }
  return 0;
}

/*
** Free all resources held by the schema structure. The void* argument points
** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the 
** pointer itself, it just cleans up subsiduary resources (i.e. the contents
** of the schema hash tables).
**
** The Schema.cache_size variable is not cleared.
*/
SQLITE_PRIVATE void sqlite3SchemaFree(void *p){
  Hash temp1;
  Hash temp2;
  HashElem *pElem;
  Schema *pSchema = (Schema *)p;

  temp1 = pSchema->tblHash;
  temp2 = pSchema->trigHash;
................................................................................
  for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
    Table *pTab = sqliteHashData(pElem);
    sqlite3DeleteTable(0, pTab);
  }
  sqlite3HashClear(&temp1);
  sqlite3HashClear(&pSchema->fkeyHash);
  pSchema->pSeqTab = 0;


  pSchema->flags &= ~DB_SchemaLoaded;

}

/*
** Find and return the schema associated with a BTree.  Create
** a new one if necessary.
*/
SQLITE_PRIVATE Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){
  Schema * p;
  if( pBt ){
    p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaFree);
  }else{
    p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));
  }
  if( !p ){
    db->mallocFailed = 1;
  }else if ( 0==p->file_format ){
    sqlite3HashInit(&p->tblHash);
................................................................................
**
*************************************************************************
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
*/

/*
** Look up every table that is named in pSrc.  If any table is not found,
** add an error message to pParse->zErrMsg and return NULL.  If all tables
** are found, return a pointer to the last table.









*/
SQLITE_PRIVATE Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
  struct SrcList_item *pItem = pSrc->a;
  Table *pTab;
  assert( pItem && pSrc->nSrc==1 );
  pTab = sqlite3LocateTable(pParse, 0, pItem->zName, pItem->zDatabase);
  sqlite3DeleteTable(pParse->db, pItem->pTab);
................................................................................
  /* Delete the index and table entries. Skip this step if pTab is really
  ** a view (in which case the only effect of the DELETE statement is to
  ** fire the INSTEAD OF triggers).  */ 
  if( pTab->pSelect==0 ){
    sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, 0);
    sqlite3VdbeAddOp2(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0));
    if( count ){
      sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
    }
  }

  /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
  ** handle rows (possibly in other tables) that refer via a foreign key
  ** to the row just deleted. */ 
  sqlite3FkActions(pParse, pTab, 0, iOld);
................................................................................
    }else{
      sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
      sqlite3ColumnDefault(v, pTab, idx, -1);
    }
  }
  if( doMakeRec ){
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
    sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v, pIdx), 0);
  }
  sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
  return regBase;
}

/************** End of delete.c **********************************************/
/************** Begin file func.c ********************************************/
................................................................................
  p = sqlite3_aggregate_context(context, sizeof(*p));
  type = sqlite3_value_numeric_type(argv[0]);
  if( p && type!=SQLITE_NULL ){
    p->cnt++;
    if( type==SQLITE_INTEGER ){
      i64 v = sqlite3_value_int64(argv[0]);
      p->rSum += v;
      if( (p->approx|p->overflow)==0 ){
        i64 iNewSum = p->iSum + v;
        int s1 = (int)(p->iSum >> (sizeof(i64)*8-1));
        int s2 = (int)(v       >> (sizeof(i64)*8-1));
        int s3 = (int)(iNewSum >> (sizeof(i64)*8-1));
        p->overflow = ((s1&s2&~s3) | (~s1&~s2&s3))?1:0;
        p->iSum = iNewSum;
      }
    }else{
      p->rSum += sqlite3_value_double(argv[0]);
      p->approx = 1;
    }
  }
}
................................................................................
          int iParent = pIdx->aiColumn[i]+1+regData;
          sqlite3VdbeAddOp3(v, OP_Ne, iChild, iJump, iParent);
        }
        sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk);
      }
  
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regTemp, nCol, regRec);
      sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v, pIdx), 0);
      sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0);
  
      sqlite3ReleaseTempReg(pParse, regRec);
      sqlite3ReleaseTempRange(pParse, regTemp, nCol);
    }
  }

................................................................................
SQLITE_PRIVATE void sqlite3FkCheck(
  Parse *pParse,                  /* Parse context */
  Table *pTab,                    /* Row is being deleted from this table */ 
  int regOld,                     /* Previous row data is stored here */
  int regNew                      /* New row data is stored here */
){
  sqlite3 *db = pParse->db;       /* Database handle */
  Vdbe *v;                        /* VM to write code to */
  FKey *pFKey;                    /* Used to iterate through FKs */
  int iDb;                        /* Index of database containing pTab */
  const char *zDb;                /* Name of database containing pTab */
  int isIgnoreErrors = pParse->disableTriggers;

  /* Exactly one of regOld and regNew should be non-zero. */
  assert( (regOld==0)!=(regNew==0) );

  /* If foreign-keys are disabled, this function is a no-op. */
  if( (db->flags&SQLITE_ForeignKeys)==0 ) return;

  v = sqlite3GetVdbe(pParse);
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  zDb = db->aDb[iDb].zName;

  /* Loop through all the foreign key constraints for which pTab is the
  ** child table (the table that the foreign key definition is part of).  */
  for(pFKey=pTab->pFKey; pFKey; pFKey=pFKey->pNextFrom){
    Table *pTo;                   /* Parent table of foreign key pFKey */
................................................................................
** table pTab. Remove the deleted foreign keys from the Schema.fkeyHash
** hash table.
*/
SQLITE_PRIVATE void sqlite3FkDelete(sqlite3 *db, Table *pTab){
  FKey *pFKey;                    /* Iterator variable */
  FKey *pNext;                    /* Copy of pFKey->pNextFrom */


  for(pFKey=pTab->pFKey; pFKey; pFKey=pNext){

    /* Remove the FK from the fkeyHash hash table. */
    if( !db || db->pnBytesFreed==0 ){
      if( pFKey->pPrevTo ){
        pFKey->pPrevTo->pNextTo = pFKey->pNextTo;
      }else{
................................................................................
      zColAff[i] = pTab->aCol[i].affinity;
    }
    zColAff[pTab->nCol] = '\0';

    pTab->zColAff = zColAff;
  }

  sqlite3VdbeChangeP4(v, -1, pTab->zColAff, 0);
}

/*
** Return non-zero if the table pTab in database iDb or any of its indices
** have been opened at any point in the VDBE program beginning at location
** iStartAddr throught the end of the program.  This is used to see if 
** a statement of the form  "INSERT INTO <iDb, pTab> SELECT ..." can 
................................................................................
  assert( pParse->pTriggerTab==0 );
  assert( pParse==sqlite3ParseToplevel(pParse) );

  assert( v );   /* We failed long ago if this is not so */
  for(p = pParse->pAinc; p; p = p->pNext){
    pDb = &db->aDb[p->iDb];
    memId = p->regCtr;

    sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenRead);
    addr = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp4(v, OP_String8, 0, memId-1, 0, p->pTab->zName, 0);
    sqlite3VdbeAddOp2(v, OP_Rewind, 0, addr+9);
    sqlite3VdbeAddOp3(v, OP_Column, 0, 0, memId);
    sqlite3VdbeAddOp3(v, OP_Ne, memId-1, addr+7, memId);
    sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
................................................................................
  for(p = pParse->pAinc; p; p = p->pNext){
    Db *pDb = &db->aDb[p->iDb];
    int j1, j2, j3, j4, j5;
    int iRec;
    int memId = p->regCtr;

    iRec = sqlite3GetTempReg(pParse);

    sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenWrite);
    j1 = sqlite3VdbeAddOp1(v, OP_NotNull, memId+1);
    j2 = sqlite3VdbeAddOp0(v, OP_Rewind);
    j3 = sqlite3VdbeAddOp3(v, OP_Column, 0, 0, iRec);
    j4 = sqlite3VdbeAddOp3(v, OP_Eq, memId-1, 0, iRec);
    sqlite3VdbeAddOp2(v, OP_Next, 0, j3);
    sqlite3VdbeJumpHere(v, j2);
................................................................................
  /* Register allocations */
  int regFromSelect = 0;/* Base register for data coming from SELECT */
  int regAutoinc = 0;   /* Register holding the AUTOINCREMENT counter */
  int regRowCount = 0;  /* Memory cell used for the row counter */
  int regIns;           /* Block of regs holding rowid+data being inserted */
  int regRowid;         /* registers holding insert rowid */
  int regData;          /* register holding first column to insert */
  int regRecord;        /* Holds the assemblied row record */
  int regEof = 0;       /* Register recording end of SELECT data */
  int *aRegIdx = 0;     /* One register allocated to each index */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                 /* True if attempting to insert into a view */
  Trigger *pTrigger;          /* List of triggers on pTab, if required */
  int tmask;                  /* Mask of trigger times */
................................................................................
    addrCont = sqlite3VdbeAddOp1(v, OP_Yield, dest.iParm);
    addrInsTop = sqlite3VdbeAddOp1(v, OP_If, regEof);
  }

  /* Allocate registers for holding the rowid of the new row,
  ** the content of the new row, and the assemblied row record.
  */
  regRecord = ++pParse->nMem;
  regRowid = regIns = pParse->nMem+1;
  pParse->nMem += pTab->nCol + 1;
  if( IsVirtual(pTab) ){
    regRowid++;
    pParse->nMem++;
  }
  regData = regRowid+1;
................................................................................
        || onError==OE_Ignore || onError==OE_Replace );
    switch( onError ){
      case OE_Abort:
        sqlite3MayAbort(pParse);
      case OE_Rollback:
      case OE_Fail: {
        char *zMsg;
        j1 = sqlite3VdbeAddOp3(v, OP_HaltIfNull,
                                  SQLITE_CONSTRAINT, onError, regData+i);
        zMsg = sqlite3MPrintf(pParse->db, "%s.%s may not be NULL",
                              pTab->zName, pTab->aCol[i].zName);
        sqlite3VdbeChangeP4(v, -1, zMsg, P4_DYNAMIC);
        break;
      }
      case OE_Ignore: {
................................................................................
        sqlite3VdbeAddOp2(v, OP_SCopy, regRowid, regIdx+i);
      }else{
        sqlite3VdbeAddOp2(v, OP_SCopy, regData+idx, regIdx+i);
      }
    }
    sqlite3VdbeAddOp2(v, OP_SCopy, regRowid, regIdx+i);
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regIdx, pIdx->nColumn+1, aRegIdx[iCur]);
    sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v, pIdx), 0);
    sqlite3ExprCacheAffinityChange(pParse, regIdx, pIdx->nColumn+1);

    /* Find out what action to take in case there is an indexing conflict */
    onError = pIdx->onError;
    if( onError==OE_None ){ 
      sqlite3ReleaseTempRange(pParse, regIdx, pIdx->nColumn+1);
      continue;  /* pIdx is not a UNIQUE index */
................................................................................
    pik_flags |= OPFLAG_APPEND;
  }
  if( useSeekResult ){
    pik_flags |= OPFLAG_USESEEKRESULT;
  }
  sqlite3VdbeAddOp3(v, OP_Insert, baseCur, regRec, regRowid);
  if( !pParse->nested ){
    sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
  }
  sqlite3VdbeChangeP5(v, pik_flags);
}

/*
** Generate code that will open cursors for a table and for all
** indices of that table.  The "baseCur" parameter is the cursor number used
................................................................................
# define sqlite3_column_origin_name16   0
#endif

#ifdef SQLITE_OMIT_COMPLETE
# define sqlite3_complete 0
# define sqlite3_complete16 0
#endif






#ifdef SQLITE_OMIT_PROGRESS_CALLBACK
# define sqlite3_progress_handler 0
#endif

#ifdef SQLITE_OMIT_VIRTUALTABLE
# define sqlite3_create_module 0
................................................................................
    if( !db->autoCommit || sqlite3BtreeIsInReadTrans(db->aDb[1].pBt) ){
      sqlite3ErrorMsg(pParse, "temporary storage cannot be changed "
        "from within a transaction");
      return SQLITE_ERROR;
    }
    sqlite3BtreeClose(db->aDb[1].pBt);
    db->aDb[1].pBt = 0;
    sqlite3ResetInternalSchema(db, 0);
  }
  return SQLITE_OK;
}
#endif /* SQLITE_PAGER_PRAGMAS */

#ifndef SQLITE_OMIT_PAGER_PRAGMAS
/*
................................................................................
      sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "cache_size", SQLITE_STATIC);
      pParse->nMem += 2;
      addr = sqlite3VdbeAddOpList(v, ArraySize(getCacheSize), getCacheSize);
      sqlite3VdbeChangeP1(v, addr, iDb);
      sqlite3VdbeChangeP1(v, addr+1, iDb);
      sqlite3VdbeChangeP1(v, addr+6, SQLITE_DEFAULT_CACHE_SIZE);
    }else{
      int size = sqlite3Atoi(zRight);
      if( size<0 ) size = -size;
      sqlite3BeginWriteOperation(pParse, 0, iDb);
      sqlite3VdbeAddOp2(v, OP_Integer, size, 1);
      sqlite3VdbeAddOp3(v, OP_SetCookie, iDb, BTREE_DEFAULT_CACHE_SIZE, 1);

      pDb->pSchema->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
    }
  }else

  /*
  **  PRAGMA [database.]page_size
................................................................................
  ** page cache size value.  It does not change the persistent
  ** cache size stored on the disk so the cache size will revert
  ** to its default value when the database is closed and reopened.
  ** N should be a positive integer.
  */
  if( sqlite3StrICmp(zLeft,"cache_size")==0 ){
    if( sqlite3ReadSchema(pParse) ) goto pragma_out;

    if( !zRight ){
      returnSingleInt(pParse, "cache_size", pDb->pSchema->cache_size);
    }else{
      int size = sqlite3Atoi(zRight);
      if( size<0 ) size = -size;
      pDb->pSchema->cache_size = size;
      sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
    }
  }else

  /*
  **   PRAGMA temp_store
................................................................................
      sqlite3VdbeJumpHere(v, addr);

      /* Do an integrity check of the B-Tree
      **
      ** Begin by filling registers 2, 3, ... with the root pages numbers
      ** for all tables and indices in the database.
      */

      pTbls = &db->aDb[i].pSchema->tblHash;
      for(x=sqliteHashFirst(pTbls); x; x=sqliteHashNext(x)){
        Table *pTab = sqliteHashData(x);
        Index *pIdx;
        sqlite3VdbeAddOp2(v, OP_Integer, pTab->tnum, 2+cnt);
        cnt++;
        for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
................................................................................
            { OP_Halt,        0,  0,  0},
          };
          r1 = sqlite3GenerateIndexKey(pParse, pIdx, 1, 3, 0);
          jmp2 = sqlite3VdbeAddOp4Int(v, OP_Found, j+2, 0, r1, pIdx->nColumn+1);
          addr = sqlite3VdbeAddOpList(v, ArraySize(idxErr), idxErr);
          sqlite3VdbeChangeP4(v, addr+1, "rowid ", P4_STATIC);
          sqlite3VdbeChangeP4(v, addr+3, " missing from index ", P4_STATIC);
          sqlite3VdbeChangeP4(v, addr+4, pIdx->zName, P4_STATIC);
          sqlite3VdbeJumpHere(v, addr+9);
          sqlite3VdbeJumpHere(v, jmp2);
        }
        sqlite3VdbeAddOp2(v, OP_Next, 1, loopTop+1);
        sqlite3VdbeJumpHere(v, loopTop);
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
          static const VdbeOpList cntIdx[] = {
................................................................................
          sqlite3VdbeChangeP1(v, addr+1, j+2);
          sqlite3VdbeChangeP2(v, addr+1, addr+4);
          sqlite3VdbeChangeP1(v, addr+3, j+2);
          sqlite3VdbeChangeP2(v, addr+3, addr+2);
          sqlite3VdbeJumpHere(v, addr+4);
          sqlite3VdbeChangeP4(v, addr+6, 
                     "wrong # of entries in index ", P4_STATIC);
          sqlite3VdbeChangeP4(v, addr+7, pIdx->zName, P4_STATIC);
        }
      } 
    }
    addr = sqlite3VdbeAddOpList(v, ArraySize(endCode), endCode);
    sqlite3VdbeChangeP2(v, addr, -mxErr);
    sqlite3VdbeJumpHere(v, addr+1);
    sqlite3VdbeChangeP4(v, addr+2, "ok", P4_STATIC);
................................................................................
      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
    }
  }else
#endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */

#ifndef SQLITE_OMIT_WAL
  /*
  **   PRAGMA [database.]wal_checkpoint
  **
  ** Checkpoint the database.
  */
  if( sqlite3StrICmp(zLeft, "wal_checkpoint")==0 ){









    if( sqlite3ReadSchema(pParse) ) goto pragma_out;






    sqlite3VdbeAddOp3(v, OP_Checkpoint, pId2->z?iDb:SQLITE_MAX_ATTACHED, 0, 0);

  }else

  /*
  **   PRAGMA wal_autocheckpoint
  **   PRAGMA wal_autocheckpoint = N
  **
  ** Configure a database connection to automatically checkpoint a database
................................................................................
    sqlite3SetString(pData->pzErrMsg, db,
      "malformed database schema (%s)", zObj);
    if( zExtra ){
      *pData->pzErrMsg = sqlite3MAppendf(db, *pData->pzErrMsg, 
                                 "%s - %s", *pData->pzErrMsg, zExtra);
    }
  }
  pData->rc = db->mallocFailed ? SQLITE_NOMEM : SQLITE_CORRUPT;
}

/*
** This is the callback routine for the code that initializes the
** database.  See sqlite3Init() below for additional information.
** This routine is also called from the OP_ParseSchema opcode of the VDBE.
**
................................................................................
  int size;
  Table *pTab;
  Db *pDb;
  char const *azArg[4];
  int meta[5];
  InitData initData;
  char const *zMasterSchema;
  char const *zMasterName = SCHEMA_TABLE(iDb);
  int openedTransaction = 0;

  /*
  ** The master database table has a structure like this
  */
  static const char master_schema[] = 
     "CREATE TABLE sqlite_master(\n"
................................................................................
    }
  }else{
    DbSetProperty(db, iDb, DB_Empty);
  }
  pDb->pSchema->enc = ENC(db);

  if( pDb->pSchema->cache_size==0 ){
    size = meta[BTREE_DEFAULT_CACHE_SIZE-1];
    if( size==0 ){ size = SQLITE_DEFAULT_CACHE_SIZE; }
    if( size<0 ) size = -size;
    pDb->pSchema->cache_size = size;
    sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
  }

  /*
  ** file_format==1    Version 3.0.0.
  ** file_format==2    Version 3.1.3.  // ALTER TABLE ADD COLUMN
................................................................................
    if( rc==SQLITE_OK ){
      sqlite3AnalysisLoad(db, iDb);
    }
#endif
  }
  if( db->mallocFailed ){
    rc = SQLITE_NOMEM;
    sqlite3ResetInternalSchema(db, 0);
  }
  if( rc==SQLITE_OK || (db->flags&SQLITE_RecoveryMode)){
    /* Black magic: If the SQLITE_RecoveryMode flag is set, then consider
    ** the schema loaded, even if errors occurred. In this situation the 
    ** current sqlite3_prepare() operation will fail, but the following one
    ** will attempt to compile the supplied statement against whatever subset
    ** of the schema was loaded before the error occurred. The primary
................................................................................
      openedTransaction = 1;
    }

    /* Read the schema cookie from the database. If it does not match the 
    ** value stored as part of the in-memory schema representation,
    ** set Parse.rc to SQLITE_SCHEMA. */
    sqlite3BtreeGetMeta(pBt, BTREE_SCHEMA_VERSION, (u32 *)&cookie);

    if( cookie!=db->aDb[iDb].pSchema->schema_cookie ){

      pParse->rc = SQLITE_SCHEMA;
    }

    /* Close the transaction, if one was opened. */
    if( openedTransaction ){
      sqlite3BtreeCommit(pBt);
    }
................................................................................
  if( db->mallocFailed ){
    pParse->rc = SQLITE_NOMEM;
  }
  if( pParse->rc==SQLITE_DONE ) pParse->rc = SQLITE_OK;
  if( pParse->checkSchema ){
    schemaIsValid(pParse);
  }
  if( pParse->rc==SQLITE_SCHEMA ){
    sqlite3ResetInternalSchema(db, 0);
  }
  if( db->mallocFailed ){
    pParse->rc = SQLITE_NOMEM;
  }
  if( pzTail ){
    *pzTail = pParse->zTail;
  }
  rc = pParse->rc;
................................................................................
  if( pParse->explain==2 ){
    Vdbe *v = pParse->pVdbe;
    char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage);
    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
  }
}

















/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of one of the two forms:
**
**   "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)"
**   "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)"
................................................................................
    char *zMsg = sqlite3MPrintf(
        pParse->db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2,
        bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op)
    );
    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
  }
}

/*
** Assign expression b to lvalue a. A second, no-op, version of this macro
** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code
** in sqlite3Select() to assign values to structure member variables that
** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the
** code with #ifndef directives.
*/
# define explainSetInteger(a, b) a = b

#else
/* No-op versions of the explainXXX() functions and macros. */
# define explainTempTable(y,z)
# define explainComposite(v,w,x,y,z)
# define explainSetInteger(y,z)
#endif

/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter.  After the loop is terminated
** we need to run the sorter and output the results.  The following
** routine generates the code needed to do that.
................................................................................
**        have a WHERE clause.
**
**  (20)  If the sub-query is a compound select, then it must not use
**        an ORDER BY clause.  Ticket #3773.  We could relax this constraint
**        somewhat by saying that the terms of the ORDER BY clause must
**        appear as unmodified result columns in the outer query.  But
**        have other optimizations in mind to deal with that case.



**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom].  isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
................................................................................
     return 0;         /* Restriction (6)  */
  }
  if( p->pOrderBy && pSub->pOrderBy ){
     return 0;                                           /* Restriction (11) */
  }
  if( isAgg && pSub->pOrderBy ) return 0;                /* Restriction (16) */
  if( pSub->pLimit && p->pWhere ) return 0;              /* Restriction (19) */




  /* OBSOLETE COMMENT 1:
  ** Restriction 3:  If the subquery is a join, make sure the subquery is 
  ** not used as the right operand of an outer join.  Examples of why this
  ** is not allowed:
  **
  **         t1 LEFT OUTER JOIN (t2 JOIN t3)
................................................................................
  for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
    sqlite3ExprCode(pParse, pC->pExpr, pC->iMem);
  }
  pAggInfo->directMode = 0;
  sqlite3ExprCacheClear(pParse);
}



























/*
** Generate code for the SELECT statement given in the p argument.  
**
** The results are distributed in various ways depending on the
** contents of the SelectDest structure pointed to by argument pDest
** as follows:
**
................................................................................
        /* Open a read-only cursor, execute the OP_Count, close the cursor. */
        sqlite3VdbeAddOp3(v, OP_OpenRead, iCsr, iRoot, iDb);
        if( pKeyInfo ){
          sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO_HANDOFF);
        }
        sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem);
        sqlite3VdbeAddOp1(v, OP_Close, iCsr);

      }else
#endif /* SQLITE_OMIT_BTREECOUNT */
      {
        /* Check if the query is of one of the following forms:
        **
        **   SELECT min(x) FROM ...
        **   SELECT max(x) FROM ...
................................................................................

  if( pParse->disableTriggers ){
    return 0;
  }

  if( pTmpSchema!=pTab->pSchema ){
    HashElem *p;

    for(p=sqliteHashFirst(&pTmpSchema->trigHash); p; p=sqliteHashNext(p)){
      Trigger *pTrig = (Trigger *)sqliteHashData(p);
      if( pTrig->pTabSchema==pTab->pSchema
       && 0==sqlite3StrICmp(pTrig->table, pTab->zName) 
      ){
        pTrig->pNext = (pList ? pList : pTab->pTrigger);
        pList = pTrig;
................................................................................

  /* Check that the trigger name is not reserved and that no trigger of the
  ** specified name exists */
  zName = sqlite3NameFromToken(db, pName);
  if( !zName || SQLITE_OK!=sqlite3CheckObjectName(pParse, zName) ){
    goto trigger_cleanup;
  }

  if( sqlite3HashFind(&(db->aDb[iDb].pSchema->trigHash),
                      zName, sqlite3Strlen30(zName)) ){
    if( !noErr ){
      sqlite3ErrorMsg(pParse, "trigger %T already exists", pName);



    }
    goto trigger_cleanup;
  }

  /* Do not create a trigger on a system table */
  if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){
    sqlite3ErrorMsg(pParse, "cannot create trigger on system table");
................................................................................
  Trigger *pTrig = pParse->pNewTrigger;   /* Trigger being finished */
  char *zName;                            /* Name of trigger */
  sqlite3 *db = pParse->db;               /* The database */
  DbFixer sFix;                           /* Fixer object */
  int iDb;                                /* Database containing the trigger */
  Token nameToken;                        /* Trigger name for error reporting */

  pTrig = pParse->pNewTrigger;
  pParse->pNewTrigger = 0;
  if( NEVER(pParse->nErr) || !pTrig ) goto triggerfinish_cleanup;
  zName = pTrig->zName;
  iDb = sqlite3SchemaToIndex(pParse->db, pTrig->pSchema);
  pTrig->step_list = pStepList;
  while( pStepList ){
    pStepList->pTrig = pTrig;
................................................................................
        db, "type='trigger' AND name='%q'", zName), P4_DYNAMIC
    );
  }

  if( db->init.busy ){
    Trigger *pLink = pTrig;
    Hash *pHash = &db->aDb[iDb].pSchema->trigHash;

    pTrig = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), pTrig);
    if( pTrig ){
      db->mallocFailed = 1;
    }else if( pLink->pSchema==pLink->pTabSchema ){
      Table *pTab;
      int n = sqlite3Strlen30(pLink->table);
      pTab = sqlite3HashFind(&pLink->pTabSchema->tblHash, pLink->table, n);
................................................................................
    goto drop_trigger_cleanup;
  }

  assert( pName->nSrc==1 );
  zDb = pName->a[0].zDatabase;
  zName = pName->a[0].zName;
  nName = sqlite3Strlen30(zName);

  for(i=OMIT_TEMPDB; i<db->nDb; i++){
    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */
    if( zDb && sqlite3StrICmp(db->aDb[j].zName, zDb) ) continue;

    pTrigger = sqlite3HashFind(&(db->aDb[j].pSchema->trigHash), zName, nName);
    if( pTrigger ) break;
  }
  if( !pTrigger ){
    if( !noErr ){
      sqlite3ErrorMsg(pParse, "no such trigger: %S", pName, 0);


    }
    pParse->checkSchema = 1;
    goto drop_trigger_cleanup;
  }
  sqlite3DropTriggerPtr(pParse, pTrigger);

drop_trigger_cleanup:
................................................................................
      { OP_Delete,     0, 0,        0},
      { OP_Next,       0, ADDR(1),  0}, /* 8 */
    };

    sqlite3BeginWriteOperation(pParse, 0, iDb);
    sqlite3OpenMasterTable(pParse, iDb);
    base = sqlite3VdbeAddOpList(v,  ArraySize(dropTrigger), dropTrigger);
    sqlite3VdbeChangeP4(v, base+1, pTrigger->zName, 0);
    sqlite3VdbeChangeP4(v, base+4, "trigger", P4_STATIC);
    sqlite3ChangeCookie(pParse, iDb);
    sqlite3VdbeAddOp2(v, OP_Close, 0, 0);
    sqlite3VdbeAddOp4(v, OP_DropTrigger, iDb, 0, 0, pTrigger->zName, 0);
    if( pParse->nMem<3 ){
      pParse->nMem = 3;
    }
................................................................................
  }
}

/*
** Remove a trigger from the hash tables of the sqlite* pointer.
*/
SQLITE_PRIVATE void sqlite3UnlinkAndDeleteTrigger(sqlite3 *db, int iDb, const char *zName){
  Hash *pHash = &(db->aDb[iDb].pSchema->trigHash);
  Trigger *pTrigger;




  pTrigger = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), 0);
  if( ALWAYS(pTrigger) ){
    if( pTrigger->pSchema==pTrigger->pTabSchema ){
      Table *pTab = tableOfTrigger(pTrigger);
      Trigger **pp;
      for(pp=&pTab->pTrigger; *pp!=pTrigger; pp=&((*pp)->pNext));
      *pp = (*pp)->pNext;
................................................................................
  Parse *pParse,          /* Parse context */
  Table *pTab,            /* The table the contains the triggers */
  int op,                 /* one of TK_DELETE, TK_INSERT, TK_UPDATE */
  ExprList *pChanges,     /* Columns that change in an UPDATE statement */
  int *pMask              /* OUT: Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
){
  int mask = 0;
  Trigger *pList = sqlite3TriggerList(pParse, pTab);
  Trigger *p;




  assert( pList==0 || IsVirtual(pTab)==0 );
  for(p=pList; p; p=p->pNext){
    if( p->op==op && checkColumnOverlap(p->pColumns, pChanges) ){
      mask |= p->tr_tm;
    }
  }
  if( pMask ){
................................................................................
  /* Register Allocations */
  int regRowCount = 0;   /* A count of rows changed */
  int regOldRowid;       /* The old rowid */
  int regNewRowid;       /* The new rowid */
  int regNew;
  int regOld = 0;
  int regRowSet = 0;     /* Rowset of rows to be updated */
  int regRec;            /* Register used for new table record to insert */

  memset(&sContext, 0, sizeof(sContext));
  db = pParse->db;
  if( pParse->nErr || db->mallocFailed ){
    goto update_cleanup;
  }
  assert( pTabList->nSrc==1 );
................................................................................
    pParse->nMem += pTab->nCol;
  }
  if( chngRowid || pTrigger || hasFK ){
    regNewRowid = ++pParse->nMem;
  }
  regNew = pParse->nMem + 1;
  pParse->nMem += pTab->nCol;
  regRec = ++pParse->nMem;

  /* Start the view context. */
  if( isView ){
    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
  }

  /* If we are trying to update a view, realize that view into
................................................................................
  ** with the required old.* column data.  */
  if( hasFK || pTrigger ){
    u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0);
    oldmask |= sqlite3TriggerColmask(pParse, 
        pTrigger, pChanges, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onError
    );
    for(i=0; i<pTab->nCol; i++){
      if( aXRef[i]<0 || oldmask==0xffffffff || (oldmask & (1<<i)) ){
        sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, i, regOld+i);
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regOld+i);
      }
    }
    if( chngRowid==0 ){
      sqlite3VdbeAddOp2(v, OP_Copy, regOldRowid, regNewRowid);
................................................................................

  if( pDb ){
    sqlite3BtreeClose(pDb->pBt);
    pDb->pBt = 0;
    pDb->pSchema = 0;
  }



  sqlite3ResetInternalSchema(db, 0);

  return rc;
}

#endif  /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */

/************** End of vacuum.c **********************************************/
/************** Begin file vtab.c ********************************************/
/*
** 2006 June 10
**
................................................................................
    if( pDel && pDel->xDestroy ){
      pDel->xDestroy(pDel->pAux);
    }
    sqlite3DbFree(db, pDel);
    if( pDel==pMod ){
      db->mallocFailed = 1;
    }
    sqlite3ResetInternalSchema(db, 0);
  }else if( xDestroy ){
    xDestroy(pAux);
  }
  rc = sqlite3ApiExit(db, SQLITE_OK);
  sqlite3_mutex_leave(db->mutex);
  return rc;
}
................................................................................
  VTable *pVTable = p->pVTable;
  p->pVTable = 0;

  /* Assert that the mutex (if any) associated with the BtShared database 
  ** that contains table p is held by the caller. See header comments 
  ** above function sqlite3VtabUnlockList() for an explanation of why
  ** this makes it safe to access the sqlite3.pDisconnect list of any
  ** database connection that may have an entry in the p->pVTable list.  */

  assert( db==0 ||
    sqlite3BtreeHoldsMutex(db->aDb[sqlite3SchemaToIndex(db, p->pSchema)].pBt) 
  );

  while( pVTable ){
    sqlite3 *db2 = pVTable->db;
    VTable *pNext = pVTable->pNext;
    assert( db2 );
    if( db2==db ){
      pRet = pVTable;
................................................................................
    );
    sqlite3DbFree(db, zStmt);
    v = sqlite3GetVdbe(pParse);
    sqlite3ChangeCookie(pParse, iDb);

    sqlite3VdbeAddOp2(v, OP_Expire, 0, 0);
    zWhere = sqlite3MPrintf(db, "name='%q' AND type='table'", pTab->zName);
    sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 1, 0, zWhere, P4_DYNAMIC);
    sqlite3VdbeAddOp4(v, OP_VCreate, iDb, 0, 0, 
                         pTab->zName, sqlite3Strlen30(pTab->zName) + 1);
  }

  /* If we are rereading the sqlite_master table create the in-memory
  ** record of the table. The xConnect() method is not called until
  ** the first time the virtual table is used in an SQL statement. This
................................................................................
  ** allows a schema that contains virtual tables to be loaded before
  ** the required virtual table implementations are registered.  */
  else {
    Table *pOld;
    Schema *pSchema = pTab->pSchema;
    const char *zName = pTab->zName;
    int nName = sqlite3Strlen30(zName);

    pOld = sqlite3HashInsert(&pSchema->tblHash, zName, nName, pTab);
    if( pOld ){
      db->mallocFailed = 1;
      assert( pTab==pOld );  /* Malloc must have failed inside HashInsert() */
      return;
    }
    pParse->pNewTable = 0;
................................................................................
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
*/


/*
** Trace output macros
*/
#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
SQLITE_PRIVATE int sqlite3WhereTrace = 0;
#endif
................................................................................
#define TERM_DYNAMIC    0x01   /* Need to call sqlite3ExprDelete(db, pExpr) */
#define TERM_VIRTUAL    0x02   /* Added by the optimizer.  Do not code */
#define TERM_CODED      0x04   /* This term is already coded */
#define TERM_COPIED     0x08   /* Has a child */
#define TERM_ORINFO     0x10   /* Need to free the WhereTerm.u.pOrInfo object */
#define TERM_ANDINFO    0x20   /* Need to free the WhereTerm.u.pAndInfo obj */
#define TERM_OR_OK      0x40   /* Used during OR-clause processing */






/*
** An instance of the following structure holds all information about a
** WHERE clause.  Mostly this is a container for one or more WhereTerms.
*/
struct WhereClause {
  Parse *pParse;           /* The parser context */
................................................................................
#define WO_LE     (WO_EQ<<(TK_LE-TK_EQ))
#define WO_GT     (WO_EQ<<(TK_GT-TK_EQ))
#define WO_GE     (WO_EQ<<(TK_GE-TK_EQ))
#define WO_MATCH  0x040
#define WO_ISNULL 0x080
#define WO_OR     0x100       /* Two or more OR-connected terms */
#define WO_AND    0x200       /* Two or more AND-connected terms */


#define WO_ALL    0xfff       /* Mask of all possible WO_* values */
#define WO_SINGLE 0x0ff       /* Mask of all non-compound WO_* values */

/*
** Value for wsFlags returned by bestIndex() and stored in
** WhereLevel.wsFlags.  These flags determine which search
................................................................................

/*
** Return the bitmask for the given cursor number.  Return 0 if
** iCursor is not in the set.
*/
static Bitmask getMask(WhereMaskSet *pMaskSet, int iCursor){
  int i;
  assert( pMaskSet->n<=sizeof(Bitmask)*8 );
  for(i=0; i<pMaskSet->n; i++){
    if( pMaskSet->ix[i]==iCursor ){
      return ((Bitmask)1)<<i;
    }
  }
  return 0;
}
................................................................................
        exprAnalyze(pSrc, pWC, idxNew);
        pTerm = &pWC->a[idxTerm];
        pWC->a[idxNew].iParent = idxTerm;
        pTerm->nChild = 1;
      }else{
        sqlite3ExprListDelete(db, pList);
      }
      pTerm->eOperator = 0;  /* case 1 trumps case 2 */
    }
  }
}
#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */


/*
................................................................................
      pTerm->nChild = 1;
      pTerm->wtFlags |= TERM_COPIED;
      pNewTerm->prereqAll = pTerm->prereqAll;
    }
  }
#endif /* SQLITE_OMIT_VIRTUALTABLE */










































  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
  ** an index for tables to the left of the join.
  */
  pTerm->prereqRight |= extraRight;
}

/*
................................................................................
static int isSortingIndex(
  Parse *pParse,          /* Parsing context */
  WhereMaskSet *pMaskSet, /* Mapping from table cursor numbers to bitmaps */
  Index *pIdx,            /* The index we are testing */
  int base,               /* Cursor number for the table to be sorted */
  ExprList *pOrderBy,     /* The ORDER BY clause */
  int nEqCol,             /* Number of index columns with == constraints */

  int *pbRev              /* Set to 1 if ORDER BY is DESC */
){
  int i, j;                       /* Loop counters */
  int sortOrder = 0;              /* XOR of index and ORDER BY sort direction */
  int nTerm;                      /* Number of ORDER BY terms */
  struct ExprList_item *pTerm;    /* A term of the ORDER BY clause */
  sqlite3 *db = pParse->db;
................................................................................
  *pbRev = sortOrder!=0;
  if( j>=nTerm ){
    /* All terms of the ORDER BY clause are covered by this index so
    ** this index can be used for sorting. */
    return 1;
  }
  if( pIdx->onError!=OE_None && i==pIdx->nColumn

      && !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){
    /* All terms of this index match some prefix of the ORDER BY clause
    ** and the index is UNIQUE and no terms on the tail of the ORDER BY
    ** clause reference other tables in a join.  If this is all true then
    ** the order by clause is superfluous. */


    return 1;
  }
  return 0;
}

/*
** Prepare a crude estimate of the logarithm of the input value.
................................................................................
    return;
  }

  /* Search for any equality comparison term */
  pWCEnd = &pWC->a[pWC->nTerm];
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
      WHERETRACE(("auto-index reduces cost from %.2f to %.2f\n",
                    pCost->rCost, costTempIdx));
      pCost->rCost = costTempIdx;
      pCost->plan.nRow = logN + 1;
      pCost->plan.wsFlags = WHERE_TEMP_INDEX;
      pCost->used = pTerm->prereqRight;
      break;
    }
................................................................................
      int iCol = pTerm->u.leftColumn;
      Bitmask cMask = iCol>=BMS ? ((Bitmask)1)<<(BMS-1) : ((Bitmask)1)<<iCol;
      if( (idxCols & cMask)==0 ){
        Expr *pX = pTerm->pExpr;
        idxCols |= cMask;
        pIdx->aiColumn[n] = pTerm->u.leftColumn;
        pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
        pIdx->azColl[n] = pColl->zName;
        n++;
      }
    }
  }
  assert( (u32)n==pLevel->plan.nEq );

  /* Add additional columns needed to make the automatic index into
................................................................................
  bestOrClauseIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost);
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

/*
** Argument pIdx is a pointer to an index structure that has an array of
** SQLITE_INDEX_SAMPLES evenly spaced samples of the first indexed column
** stored in Index.aSample. The domain of values stored in said column
** may be thought of as divided into (SQLITE_INDEX_SAMPLES+1) regions.
** Region 0 contains all values smaller than the first sample value. Region


** 1 contains values larger than or equal to the value of the first sample,
** but smaller than the value of the second. And so on.






**
** If successful, this function determines which of the regions value 
** pVal lies in, sets *piRegion to the region index (a value between 0
** and SQLITE_INDEX_SAMPLES+1, inclusive) and returns SQLITE_OK.
** Or, if an OOM occurs while converting text values between encodings,
** SQLITE_NOMEM is returned and *piRegion is undefined.
*/
#ifdef SQLITE_ENABLE_STAT2
static int whereRangeRegion(
  Parse *pParse,              /* Database connection */
  Index *pIdx,                /* Index to consider domain of */
  sqlite3_value *pVal,        /* Value to consider */

  int *piRegion               /* OUT: Region of domain in which value lies */
){

  if( ALWAYS(pVal) ){
    IndexSample *aSample = pIdx->aSample;
    int i = 0;
    int eType = sqlite3_value_type(pVal);

    if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
      double r = sqlite3_value_double(pVal);
      for(i=0; i<SQLITE_INDEX_SAMPLES; i++){
        if( aSample[i].eType==SQLITE_NULL ) continue;
        if( aSample[i].eType>=SQLITE_TEXT || aSample[i].u.r>r ) break;










      }
    }else{ 
      sqlite3 *db = pParse->db;
      CollSeq *pColl;
      const u8 *z;
      int n;

................................................................................
          return SQLITE_NOMEM;
        }
        assert( z && pColl && pColl->xCmp );
      }
      n = sqlite3ValueBytes(pVal, pColl->enc);

      for(i=0; i<SQLITE_INDEX_SAMPLES; i++){
        int r;
        int eSampletype = aSample[i].eType;
        if( eSampletype==SQLITE_NULL || eSampletype<eType ) continue;
        if( (eSampletype!=eType) ) break;
#ifndef SQLITE_OMIT_UTF16
        if( pColl->enc!=SQLITE_UTF8 ){
          int nSample;
          char *zSample = sqlite3Utf8to16(
              db, pColl->enc, aSample[i].u.z, aSample[i].nByte, &nSample
          );
          if( !zSample ){
            assert( db->mallocFailed );
            return SQLITE_NOMEM;
          }
          r = pColl->xCmp(pColl->pUser, nSample, zSample, n, z);
          sqlite3DbFree(db, zSample);
        }else
#endif
        {
          r = pColl->xCmp(pColl->pUser, aSample[i].nByte, aSample[i].u.z, n, z);
        }
        if( r>0 ) break;
      }
    }

    assert( i>=0 && i<=SQLITE_INDEX_SAMPLES );
    *piRegion = i;
  }
  return SQLITE_OK;
................................................................................
** value of 1 indicates that the proposed range scan is expected to visit
** approximately 1/100th (1%) of the rows selected by the nEq equality
** constraints (if any). A return value of 100 indicates that it is expected
** that the range scan will visit every row (100%) selected by the equality
** constraints.
**
** In the absence of sqlite_stat2 ANALYZE data, each range inequality
** reduces the search space by 2/3rds.  Hence a single constraint (x>?)
** results in a return of 33 and a range constraint (x>? AND x<?) results
** in a return of 11.
*/
static int whereRangeScanEst(
  Parse *pParse,       /* Parsing & code generating context */
  Index *p,            /* The index containing the range-compared column; "x" */
  int nEq,             /* index into p->aCol[] of the range-compared column */
  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
................................................................................

  if( nEq==0 && p->aSample ){
    sqlite3_value *pLowerVal = 0;
    sqlite3_value *pUpperVal = 0;
    int iEst;
    int iLower = 0;
    int iUpper = SQLITE_INDEX_SAMPLES;


    u8 aff = p->pTable->aCol[p->aiColumn[0]].affinity;

    if( pLower ){
      Expr *pExpr = pLower->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pLowerVal);


    }
    if( rc==SQLITE_OK && pUpper ){
      Expr *pExpr = pUpper->pExpr->pRight;
      rc = valueFromExpr(pParse, pExpr, aff, &pUpperVal);


    }

    if( rc!=SQLITE_OK || (pLowerVal==0 && pUpperVal==0) ){
      sqlite3ValueFree(pLowerVal);
      sqlite3ValueFree(pUpperVal);
      goto range_est_fallback;
    }else if( pLowerVal==0 ){
      rc = whereRangeRegion(pParse, p, pUpperVal, &iUpper);
      if( pLower ) iLower = iUpper/2;
    }else if( pUpperVal==0 ){
      rc = whereRangeRegion(pParse, p, pLowerVal, &iLower);
      if( pUpper ) iUpper = (iLower + SQLITE_INDEX_SAMPLES + 1)/2;
    }else{
      rc = whereRangeRegion(pParse, p, pUpperVal, &iUpper);
      if( rc==SQLITE_OK ){
        rc = whereRangeRegion(pParse, p, pLowerVal, &iLower);
      }
    }


    iEst = iUpper - iLower;
    testcase( iEst==SQLITE_INDEX_SAMPLES );
    assert( iEst<=SQLITE_INDEX_SAMPLES );
    if( iEst<1 ){
      iEst = 1;
    }


    sqlite3ValueFree(pLowerVal);
    sqlite3ValueFree(pUpperVal);
    *piEst = (iEst * 100)/SQLITE_INDEX_SAMPLES;
    return rc;
  }
range_est_fallback:
#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(p);
  UNUSED_PARAMETER(nEq);
#endif
  assert( pLower || pUpper );
  if( pLower && pUpper ){
    *piEst = 11;








































  }else{
    *piEst = 33;

  }
















  return rc;
}

















































































/*
** Find the query plan for accessing a particular table.  Write the
** best query plan and its cost into the WhereCost object supplied as the
** last parameter.
**
** The lowest cost plan wins.  The cost is an estimate of the amount of
** CPU and disk I/O need to process the request using the selected plan.
** Factors that influence cost include:
**
**    *  The estimated number of rows that will be retrieved.  (The
**       fewer the better.)
**
**    *  Whether or not sorting must occur.
**
................................................................................
** the SQL statement, then this function only considers plans using the 
** named index. If no such plan is found, then the returned cost is
** SQLITE_BIG_DBL. If a plan is found that uses the named index, 
** then the cost is calculated in the usual way.
**
** If a NOT INDEXED clause (pSrc->notIndexed!=0) was attached to the table 
** in the SELECT statement, then no indexes are considered. However, the 
** selected plan may still take advantage of the tables built-in rowid
** index.
*/
static void bestBtreeIndex(
  Parse *pParse,              /* The parsing context */
  WhereClause *pWC,           /* The WHERE clause */
  struct SrcList_item *pSrc,  /* The FROM clause term to search */
  Bitmask notReady,           /* Mask of cursors not available for indexing */
................................................................................

  if( pSrc->pIndex ){
    /* An INDEXED BY clause specifies a particular index to use */
    pIdx = pProbe = pSrc->pIndex;
    wsFlagMask = ~(WHERE_ROWID_EQ|WHERE_ROWID_RANGE);
    eqTermMask = idxEqTermMask;
  }else{
    /* There is no INDEXED BY clause.  Create a fake Index object to
    ** represent the primary key */


    Index *pFirst;                /* Any other index on the table */
    memset(&sPk, 0, sizeof(Index));
    sPk.nColumn = 1;
    sPk.aiColumn = &aiColumnPk;
    sPk.aiRowEst = aiRowEstPk;
    sPk.onError = OE_Replace;
    sPk.pTable = pSrc->pTab;
    aiRowEstPk[0] = pSrc->pTab->nRowEst;
    aiRowEstPk[1] = 1;
    pFirst = pSrc->pTab->pIndex;
    if( pSrc->notIndexed==0 ){


      sPk.pNext = pFirst;
    }
    pProbe = &sPk;
    wsFlagMask = ~(
        WHERE_COLUMN_IN|WHERE_COLUMN_EQ|WHERE_COLUMN_NULL|WHERE_COLUMN_RANGE
    );
    eqTermMask = WO_EQ|WO_IN;
................................................................................

  /* Loop over all indices looking for the best one to use
  */
  for(; pProbe; pIdx=pProbe=pProbe->pNext){
    const unsigned int * const aiRowEst = pProbe->aiRowEst;
    double cost;                /* Cost of using pProbe */
    double nRow;                /* Estimated number of rows in result set */

    int rev;                    /* True to scan in reverse order */
    int wsFlags = 0;
    Bitmask used = 0;

    /* The following variables are populated based on the properties of
    ** scan being evaluated. They are then used to determine the expected
    ** cost and number of rows returned.
    **
    **  nEq: 
    **    Number of equality terms that can be implemented using the index.


    **
    **  nInMul:  
    **    The "in-multiplier". This is an estimate of how many seek operations 
    **    SQLite must perform on the index in question. For example, if the 
    **    WHERE clause is:
    **
    **      WHERE a IN (1, 2, 3) AND b IN (4, 5, 6)
................................................................................
    **
    **    If there exists a WHERE term of the form "x IN (SELECT ...)", then 
    **    the sub-select is assumed to return 25 rows for the purposes of 
    **    determining nInMul.
    **
    **  bInEst:  
    **    Set to true if there was at least one "x IN (SELECT ...)" term used 
    **    in determining the value of nInMul.


    **
    **  estBound:
    **    An estimate on the amount of the table that must be searched.  A
    **    value of 100 means the entire table is searched.  Range constraints
    **    might reduce this to a value less than 100 to indicate that only
    **    a fraction of the table needs searching.  In the absence of
    **    sqlite_stat2 ANALYZE data, a single inequality reduces the search
    **    space to 1/3rd its original size.  So an x>? constraint reduces
    **    estBound to 33.  Two constraints (x>? AND x<?) reduce estBound to 11.
    **
    **  bSort:   
    **    Boolean. True if there is an ORDER BY clause that will require an 
    **    external sort (i.e. scanning the index being evaluated will not 
    **    correctly order records).
    **
    **  bLookup: 
    **    Boolean. True if for each index entry visited a lookup on the 
    **    corresponding table b-tree is required. This is always false 

    **    for the rowid index. For other indexes, it is true unless all the 
    **    columns of the table used by the SELECT statement are present in 
    **    the index (such an index is sometimes described as a covering index).
    **    For example, given the index on (a, b), the second of the following 
    **    two queries requires table b-tree lookups, but the first does not.


    **
    **             SELECT a, b    FROM tbl WHERE a = 1;
    **             SELECT a, b, c FROM tbl WHERE a = 1;
    */
    int nEq;
    int bInEst = 0;
    int nInMul = 1;
    int estBound = 100;
    int nBound = 0;             /* Number of range constraints seen */
    int bSort = 0;
    int bLookup = 0;
    WhereTerm *pTerm;           /* A single term of the WHERE clause */




    /* Determine the values of nEq and nInMul */
    for(nEq=0; nEq<pProbe->nColumn; nEq++){
      int j = pProbe->aiColumn[nEq];
      pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pIdx);
      if( pTerm==0 ) break;
      wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);
      if( pTerm->eOperator & WO_IN ){
        Expr *pExpr = pTerm->pExpr;
        wsFlags |= WHERE_COLUMN_IN;
        if( ExprHasProperty(pExpr, EP_xIsSelect) ){

          nInMul *= 25;
          bInEst = 1;
        }else if( ALWAYS(pExpr->x.pList) ){

          nInMul *= pExpr->x.pList->nExpr + 1;
        }
      }else if( pTerm->eOperator & WO_ISNULL ){
        wsFlags |= WHERE_COLUMN_NULL;
      }



      used |= pTerm->prereqRight;
    }

    /* Determine the value of estBound. */
    if( nEq<pProbe->nColumn ){
      int j = pProbe->aiColumn[nEq];
      if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){
        WhereTerm *pTop = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pIdx);
        WhereTerm *pBtm = findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pIdx);
        whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &estBound);
        if( pTop ){
          nBound = 1;
................................................................................
    }

    /* If there is an ORDER BY clause and the index being considered will
    ** naturally scan rows in the required order, set the appropriate flags
    ** in wsFlags. Otherwise, if there is an ORDER BY clause but the index
    ** will scan rows in a different order, set the bSort variable.  */
    if( pOrderBy ){
      if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0

        && isSortingIndex(pParse,pWC->pMaskSet,pProbe,iCur,pOrderBy,nEq,&rev)

      ){
        wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;
        wsFlags |= (rev ? WHERE_REVERSE : 0);
      }else{
        bSort = 1;
      }
    }
................................................................................
        wsFlags |= WHERE_IDX_ONLY;
      }else{
        bLookup = 1;
      }
    }

    /*
    ** Estimate the number of rows of output.  For an IN operator,
    ** do not let the estimate exceed half the rows in the table.
    */
    nRow = (double)(aiRowEst[nEq] * nInMul);
    if( bInEst && nRow*2>aiRowEst[0] ){
      nRow = aiRowEst[0]/2;
      nInMul = (int)(nRow / aiRowEst[nEq]);
    }

    /* Assume constant cost to access a row and logarithmic cost to
    ** do a binary search.  Hence, the initial cost is the number of output
    ** rows plus log2(table-size) times the number of binary searches.


    */
    cost = nRow + nInMul*estLog(aiRowEst[0]);











    /* Adjust the number of rows and the cost downward to reflect rows
    ** that are excluded by range constraints.
    */
    nRow = (nRow * (double)estBound) / (double)100;
    cost = (cost * (double)estBound) / (double)100;


    /* Add in the estimated cost of sorting the result












    */















    if( bSort ){
      cost += cost*estLog(cost);












    }







    /* If all information can be taken directly from the index, we avoid
    ** doing table lookups.  This reduces the cost by half.  (Not really -
    ** this needs to be fixed.)







    */
    if( pIdx && bLookup==0 ){
      cost /= (double)2;


    }

    /**** Cost of using this index has now been computed ****/

    /* If there are additional constraints on this table that cannot
    ** be used with the current index, but which might lower the number
    ** of output rows, adjust the nRow value accordingly.  This only 
    ** matters if the current index is the least costly, so do not bother
    ** with this step if we already know this index will not be chosen.
................................................................................
          }else{
            /* Assume each additional equality match reduces the result
            ** set size by a factor of 10 */
            nRow /= 10;
          }
        }else if( pTerm->eOperator & (WO_LT|WO_LE|WO_GT|WO_GE) ){
          if( nSkipRange ){
            /* Ignore the first nBound range constraints since the index
            ** has already accounted for these */
            nSkipRange--;
          }else{
            /* Assume each additional range constraint reduces the result
            ** set size by a factor of 3 */




            nRow /= 3;
          }
        }else{

          /* Any other expression lowers the output row count by half */
          nRow /= 2;
        }
      }
      if( nRow<2 ) nRow = 2;
    }


    WHERETRACE((
      "%s(%s): nEq=%d nInMul=%d estBound=%d bSort=%d bLookup=%d wsFlags=0x%x\n"
      "         notReady=0x%llx nRow=%.2f cost=%.2f used=0x%llx\n",
      pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"), 
      nEq, nInMul, estBound, bSort, bLookup, wsFlags,
      notReady, nRow, cost, used
    ));

    /* If this index is the best we have seen so far, then record this
    ** index and its cost in the pCost structure.
    */
    if( (!pIdx || wsFlags)
     && (cost<pCost->rCost || (cost<=pCost->rCost && nRow<pCost->plan.nRow))
................................................................................
    start_constraints = pRangeStart || nEq>0;

    /* Seek the index cursor to the start of the range. */
    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);

      sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt);

      if( zStartAff ){
        if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */
          zStartAff[nEq] = SQLITE_AFF_NONE;
        }
................................................................................
    ** range (if any).
    */
    nConstraint = nEq;
    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);

      sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt);

      if( zEndAff ){
        if( sqlite3CompareAffinity(pRight, zEndAff[nEq])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */
          zEndAff[nEq] = SQLITE_AFF_NONE;
        }
................................................................................
      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
      sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg);  /* Deferred seek */
    }

    /* Record the instruction used to terminate the loop. Disable 
    ** WHERE clause terms made redundant by the index range scan.
    */

    pLevel->op = bRev ? OP_Prev : OP_Next;





    pLevel->p1 = iIdxCur;
  }else

#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){
    /* Case 4:  Two or more separately indexed terms connected by OR
    **
................................................................................
    **
    **          Return     2                # Jump back to the Gosub
    **
    **       B: <after the loop>
    **
    */
    WhereClause *pOrWc;    /* The OR-clause broken out into subterms */
    WhereTerm *pFinal;     /* Final subterm within the OR-clause. */
    SrcList *pOrTab;       /* Shortened table list or OR-clause generation */

    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
    int regRowset = 0;                        /* Register for RowSet object */
    int regRowid = 0;                         /* Register holding rowid */
    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
    int iRetInit;                             /* Address of regReturn init */
................................................................................
    int ii;
   
    pTerm = pLevel->plan.u.pTerm;
    assert( pTerm!=0 );
    assert( pTerm->eOperator==WO_OR );
    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
    pOrWc = &pTerm->u.pOrInfo->wc;
    pFinal = &pOrWc->a[pOrWc->nTerm-1];
    pLevel->op = OP_Return;
    pLevel->p1 = regReturn;

    /* Set up a new SrcList ni pOrTab containing the table being scanned
    ** by this loop in the a[0] slot and all notReady tables in a[1..] slots.
    ** This becomes the SrcList in the recursive call to sqlite3WhereBegin().
    */
................................................................................
  /* Insert code to test every subexpression that can be completely
  ** computed using the current set of tables.
  **
  ** IMPLEMENTATION-OF: R-49525-50935 Terms that cannot be satisfied through
  ** the use of indices become tests that are evaluated against each row of
  ** the relevant input tables.
  */
  k = 0;
  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
    Expr *pE;
    testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* IMP: R-30575-11662 */
    testcase( pTerm->wtFlags & TERM_CODED );
    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
    if( (pTerm->prereqAll & notReady)!=0 ){
      testcase( pWInfo->untestedTerms==0
................................................................................
    }
    pE = pTerm->pExpr;
    assert( pE!=0 );
    if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
      continue;
    }
    sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
    k = 1;
    pTerm->wtFlags |= TERM_CODED;
  }

  /* For a LEFT OUTER JOIN, generate code that will record the fact that
  ** at least one row of the right table has matched the left table.  
  */
  if( pLevel->iLeftJoin ){
................................................................................
  **   pWInfo->a[].iIdxCur   The VDBE cursor for the index
  **   pWInfo->a[].pTerm     When wsFlags==WO_OR, the OR-clause term
  **
  ** This loop also figures out the nesting order of tables in the FROM
  ** clause.
  */
  notReady = ~(Bitmask)0;
  pTabItem = pTabList->a;
  pLevel = pWInfo->a;
  andFlags = ~0;
  WHERETRACE(("*** Optimizer Start ***\n"));
  for(i=iFrom=0, pLevel=pWInfo->a; i<nTabList; i++, pLevel++){
    WhereCost bestPlan;         /* Most efficient plan seen so far */
    Index *pIdx;                /* Index for FROM table at pTabItem */
    int j;                      /* For looping over FROM tables */
    int bestJ = -1;             /* The value of j */
................................................................................
        }

        /* Conditions under which this table becomes the best so far:
        **
        **   (1) The table must not depend on other tables that have not
        **       yet run.
        **
        **   (2) A full-table-scan plan cannot supercede another plan unless
        **       it is an "optimal" plan as defined above.
        **
        **   (3) All tables have an INDEXED BY clause or this table lacks an
        **       INDEXED BY clause or this table uses the specific
        **       index specified by its INDEXED BY clause.  This rule ensures
        **       that a best-so-far is always selected even if an impossible
        **       combination of INDEXED BY clauses are given.  The error
        **       will be detected and relayed back to the application later.
................................................................................
        **       An indexable full-table-scan from reaching rule (3).
        **
        **   (4) The plan cost must be lower than prior plans or else the
        **       cost must be the same and the number of rows must be lower.
        */
        if( (sCost.used&notReady)==0                       /* (1) */
            && (bestJ<0 || (notIndexed&m)!=0               /* (2) */

                || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0)
            && (nUnconstrained==0 || pTabItem->pIndex==0   /* (3) */
                || NEVER((sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0))
            && (bestJ<0 || sCost.rCost<bestPlan.rCost      /* (4) */
                || (sCost.rCost<=bestPlan.rCost 
                 && sCost.plan.nRow<bestPlan.plan.nRow))
        ){
................................................................................

#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
    case SQLITE_CONFIG_HEAP: {
      /* Designate a buffer for heap memory space */
      sqlite3GlobalConfig.pHeap = va_arg(ap, void*);
      sqlite3GlobalConfig.nHeap = va_arg(ap, int);
      sqlite3GlobalConfig.mnReq = va_arg(ap, int);








      if( sqlite3GlobalConfig.pHeap==0 ){
        /* If the heap pointer is NULL, then restore the malloc implementation
        ** back to NULL pointers too.  This will cause the malloc to go
        ** back to its default implementation when sqlite3_initialize() is
        ** run.
        */
................................................................................
*/
SQLITE_API int sqlite3_db_config(sqlite3 *db, int op, ...){
  va_list ap;
  int rc;
  va_start(ap, op);
  switch( op ){
    case SQLITE_DBCONFIG_LOOKASIDE: {
      void *pBuf = va_arg(ap, void*); /* IMP: R-21112-12275 */
      int sz = va_arg(ap, int);       /* IMP: R-47871-25994 */
      int cnt = va_arg(ap, int);      /* IMP: R-04460-53386 */
      rc = setupLookaside(db, pBuf, sz, cnt);
      break;
    }
    default: {








      rc = SQLITE_ERROR; /* IMP: R-42790-23372 */




















      break;
    }
  }
  va_end(ap);
  return rc;
}

................................................................................
    return SQLITE_OK;
  }
  if( !sqlite3SafetyCheckSickOrOk(db) ){
    return SQLITE_MISUSE_BKPT;
  }
  sqlite3_mutex_enter(db->mutex);


  sqlite3ResetInternalSchema(db, 0);

  /* If a transaction is open, the ResetInternalSchema() call above
  ** will not have called the xDisconnect() method on any virtual
  ** tables in the db->aVTrans[] array. The following sqlite3VtabRollback()
  ** call will do so. We need to do this before the check for active
  ** SQL statements below, as the v-table implementation may be storing
  ** some prepared statements internally.
................................................................................
      sqlite3BtreeClose(pDb->pBt);
      pDb->pBt = 0;
      if( j!=1 ){
        pDb->pSchema = 0;
      }
    }
  }
  sqlite3ResetInternalSchema(db, 0);

  /* Tell the code in notify.c that the connection no longer holds any
  ** locks and does not require any further unlock-notify callbacks.
  */
  sqlite3ConnectionClosed(db);

  assert( db->nDb<=2 );
................................................................................
    }
  }
  sqlite3VtabRollback(db);
  sqlite3EndBenignMalloc();

  if( db->flags&SQLITE_InternChanges ){
    sqlite3ExpirePreparedStatements(db);
    sqlite3ResetInternalSchema(db, 0);
  }

  /* Any deferred constraint violations have now been resolved. */
  db->nDeferredCons = 0;

  /* If one has been configured, invoke the rollback-hook callback */
  if( db->xRollbackCallback && (inTrans || !db->autoCommit) ){
................................................................................
 int count                /* Number of times table has been busy */
){
#if SQLITE_OS_WIN || (defined(HAVE_USLEEP) && HAVE_USLEEP)
  static const u8 delays[] =
     { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
  static const u8 totals[] =
     { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
# define NDELAY (sizeof(delays)/sizeof(delays[0]))
  sqlite3 *db = (sqlite3 *)ptr;
  int timeout = db->busyTimeout;
  int delay, prior;

  assert( count>=0 );
  if( count < NDELAY ){
    delay = delays[count];
................................................................................
  sqlite3_mutex_leave(db->mutex);
  return pRet;
#else
  return 0;
#endif
}


/*
** Checkpoint database zDb. If zDb is NULL, or if the buffer zDb points
** to contains a zero-length string, all attached databases are 
** checkpointed.
*/
SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb){



#ifdef SQLITE_OMIT_WAL
  return SQLITE_OK;
#else
  int rc;                         /* Return code */
  int iDb = SQLITE_MAX_ATTACHED;  /* sqlite3.aDb[] index of db to checkpoint */












  sqlite3_mutex_enter(db->mutex);
  if( zDb && zDb[0] ){
    iDb = sqlite3FindDbName(db, zDb);
  }
  if( iDb<0 ){
    rc = SQLITE_ERROR;
    sqlite3Error(db, SQLITE_ERROR, "unknown database: %s", zDb);
  }else{
    rc = sqlite3Checkpoint(db, iDb);
    sqlite3Error(db, rc, 0);
  }
  rc = sqlite3ApiExit(db, rc);
  sqlite3_mutex_leave(db->mutex);
  return rc;
#endif
}











#ifndef SQLITE_OMIT_WAL
/*
** Run a checkpoint on database iDb. This is a no-op if database iDb is
** not currently open in WAL mode.
**
** If a transaction is open on the database being checkpointed, this 
** function returns SQLITE_LOCKED and a checkpoint is not attempted. If 
................................................................................
** The mutex on database handle db should be held by the caller. The mutex
** associated with the specific b-tree being checkpointed is taken by
** this function while the checkpoint is running.
**
** If iDb is passed SQLITE_MAX_ATTACHED, then all attached databases are
** checkpointed. If an error is encountered it is returned immediately -
** no attempt is made to checkpoint any remaining databases.


*/
SQLITE_PRIVATE int sqlite3Checkpoint(sqlite3 *db, int iDb){
  int rc = SQLITE_OK;             /* Return code */
  int i;                          /* Used to iterate through attached dbs */


  assert( sqlite3_mutex_held(db->mutex) );



  for(i=0; i<db->nDb && rc==SQLITE_OK; i++){
    if( i==iDb || iDb==SQLITE_MAX_ATTACHED ){
      rc = sqlite3BtreeCheckpoint(db->aDb[i].pBt);






    }
  }

  return rc;
}
#endif /* SQLITE_OMIT_WAL */

/*
** This function returns true if main-memory should be used instead of
** a temporary file for transient pager files and statement journals.
** The value returned depends on the value of db->temp_store (runtime
................................................................................
#endif
#if SQLITE_MAX_VDBE_OP<40
# error SQLITE_MAX_VDBE_OP must be at least 40
#endif
#if SQLITE_MAX_FUNCTION_ARG<0 || SQLITE_MAX_FUNCTION_ARG>1000
# error SQLITE_MAX_FUNCTION_ARG must be between 0 and 1000
#endif
#if SQLITE_MAX_ATTACHED<0 || SQLITE_MAX_ATTACHED>30
# error SQLITE_MAX_ATTACHED must be between 0 and 30
#endif
#if SQLITE_MAX_LIKE_PATTERN_LENGTH<1
# error SQLITE_MAX_LIKE_PATTERN_LENGTH must be at least 1
#endif
#if SQLITE_MAX_COLUMN>32767
# error SQLITE_MAX_COLUMN must not exceed 32767
#endif
................................................................................
  }

  /* Remove harmful bits from the flags parameter
  **
  ** The SQLITE_OPEN_NOMUTEX and SQLITE_OPEN_FULLMUTEX flags were
  ** dealt with in the previous code block.  Besides these, the only
  ** valid input flags for sqlite3_open_v2() are SQLITE_OPEN_READONLY,
  ** SQLITE_OPEN_READWRITE, and SQLITE_OPEN_CREATE.  Silently mask

  ** off all other flags.
  */
  flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
               SQLITE_OPEN_EXCLUSIVE |
               SQLITE_OPEN_MAIN_DB |
               SQLITE_OPEN_TEMP_DB | 
               SQLITE_OPEN_TRANSIENT_DB | 
................................................................................
  db->aDb = db->aDbStatic;

  assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
  memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
  db->autoCommit = 1;
  db->nextAutovac = -1;
  db->nextPagesize = 0;
  db->flags |= SQLITE_ShortColNames | SQLITE_AutoIndex
#if SQLITE_DEFAULT_FILE_FORMAT<4
                 | SQLITE_LegacyFileFmt
#endif
#ifdef SQLITE_ENABLE_LOAD_EXTENSION
                 | SQLITE_LoadExtension
#endif
#if SQLITE_DEFAULT_RECURSIVE_TRIGGERS
................................................................................
typedef struct Fts3Expr Fts3Expr;
typedef struct Fts3Phrase Fts3Phrase;
typedef struct Fts3PhraseToken Fts3PhraseToken;

typedef struct Fts3SegFilter Fts3SegFilter;
typedef struct Fts3DeferredToken Fts3DeferredToken;
typedef struct Fts3SegReader Fts3SegReader;
typedef struct Fts3SegReaderArray Fts3SegReaderArray;

/*
** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
................................................................................
  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[24];




  int nNodeSize;                  /* Soft limit for node size */
  u8 bHasStat;                    /* True if %_stat table exists */
  u8 bHasDocsize;                 /* True if %_docsize table exists */
  int nPgsz;                      /* Page size for host database */
  char *zSegmentsTbl;             /* Name of %_segments table */
  sqlite3_blob *pSegments;        /* Blob handle open on %_segments table */

................................................................................
** on the assumption that the 
*/
struct Fts3PhraseToken {
  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */
  int bFulltext;                  /* True if full-text index was used */
  Fts3SegReaderArray *pArray;     /* Segment-reader for this token */
  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
};

struct Fts3Phrase {
  /* Variables populated by fts3_expr.c when parsing a MATCH expression */
  int nToken;                /* Number of tokens in the phrase */
  int iColumn;               /* Index of column this phrase must match */
................................................................................
SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *);
SQLITE_PRIVATE void sqlite3Fts3PendingTermsClear(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3SegReaderNew(int, sqlite3_int64,
  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
SQLITE_PRIVATE int sqlite3Fts3SegReaderPending(Fts3Table*,const char*,int,int,Fts3SegReader**);
SQLITE_PRIVATE void sqlite3Fts3SegReaderFree(Fts3SegReader *);
SQLITE_PRIVATE int sqlite3Fts3SegReaderIterate(
  Fts3Table *, Fts3SegReader **, int, Fts3SegFilter *,
  int (*)(Fts3Table *, void *, char *, int, char *, int),  void *
);
SQLITE_PRIVATE int sqlite3Fts3SegReaderCost(Fts3Cursor *, Fts3SegReader *, int *);
SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(Fts3Table*, sqlite3_stmt **);
SQLITE_PRIVATE int sqlite3Fts3ReadLock(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char **, int*);

SQLITE_PRIVATE int sqlite3Fts3SelectDoctotal(Fts3Table *, sqlite3_stmt **);
SQLITE_PRIVATE int sqlite3Fts3SelectDocsize(Fts3Table *, sqlite3_int64, sqlite3_stmt **);

SQLITE_PRIVATE void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *);
SQLITE_PRIVATE int sqlite3Fts3DeferToken(Fts3Cursor *, Fts3PhraseToken *, int);
SQLITE_PRIVATE int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *);
SQLITE_PRIVATE void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *);
SQLITE_PRIVATE char *sqlite3Fts3DeferredDoclist(Fts3DeferredToken *, int *);







SQLITE_PRIVATE void sqlite3Fts3SegmentsClose(Fts3Table *);



/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
#define FTS3_SEGMENT_PREFIX        0x00000008


/* Type passed as 4th argument to SegmentReaderIterate() */
struct Fts3SegFilter {
  const char *zTerm;
  int nTerm;
  int iCol;
  int flags;
};




















/* fts3.c */
SQLITE_PRIVATE int sqlite3Fts3PutVarint(char *, sqlite3_int64);
SQLITE_PRIVATE int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
SQLITE_PRIVATE int sqlite3Fts3GetVarint32(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64);
SQLITE_PRIVATE void sqlite3Fts3Dequote(char *);
................................................................................
  char **, int, int, const char *, int, Fts3Expr **
);
SQLITE_PRIVATE void sqlite3Fts3ExprFree(Fts3Expr *);
#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
#endif




#endif /* _FTSINT_H */

/************** End of fts3Int.h *********************************************/
/************** Continuing where we left off in fts3.c ***********************/


#ifndef SQLITE_CORE 
................................................................................
  assert( p->pSegments==0 );

  /* Free any prepared statements held */
  for(i=0; i<SizeofArray(p->aStmt); i++){
    sqlite3_finalize(p->aStmt[i]);
  }
  sqlite3_free(p->zSegmentsTbl);



  /* Invoke the tokenizer destructor to free the tokenizer. */
  p->pTokenizer->pModule->xDestroy(p->pTokenizer);

  sqlite3_free(p);
  return SQLITE_OK;
}
................................................................................
  zValue = sqlite3_mprintf("%s", &zCsr[1]);
  if( zValue ){
    sqlite3Fts3Dequote(zValue);
  }
  *pzValue = zValue;
  return 1;
}








































































































































/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
................................................................................
  int nDb;                        /* Bytes required to hold database name */
  int nName;                      /* Bytes required to hold table name */
  int isFts4 = (argv[0][3]=='4'); /* True for FTS4, false for FTS3 */
  int bNoDocsize = 0;             /* True to omit %_docsize table */
  const char **aCol;              /* Array of column names */
  sqlite3_tokenizer *pTokenizer = 0;        /* Tokenizer for this table */




  assert( strlen(argv[0])==4 );
  assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
       || (sqlite3_strnicmp(argv[0], "fts3", 4)==0 && !isFts4)
  );

  nDb = (int)strlen(argv[1]) + 1;
  nName = (int)strlen(argv[2]) + 1;
................................................................................
      if( nKey==9 && 0==sqlite3_strnicmp(z, "matchinfo", 9) ){
        if( strlen(zVal)==4 && 0==sqlite3_strnicmp(zVal, "fts3", 4) ){
          bNoDocsize = 1;
        }else{
          *pzErr = sqlite3_mprintf("unrecognized matchinfo: %s", zVal);
          rc = SQLITE_ERROR;
        }






      }else{
        *pzErr = sqlite3_mprintf("unrecognized parameter: %s", z);
        rc = SQLITE_ERROR;
      }
      sqlite3_free(zVal);
    }

................................................................................
    memcpy(zCsr, z, n);
    zCsr[n] = '\0';
    sqlite3Fts3Dequote(zCsr);
    p->azColumn[iCol] = zCsr;
    zCsr += n+1;
    assert( zCsr <= &((char *)p)[nByte] );
  }










  /* If this is an xCreate call, create the underlying tables in the 
  ** database. TODO: For xConnect(), it could verify that said tables exist.
  */
  if( isCreate ){
    rc = fts3CreateTables(p);
  }
................................................................................
  */
  fts3DatabasePageSize(&rc, p);

  /* Declare the table schema to SQLite. */
  fts3DeclareVtab(&rc, p);

fts3_init_out:


  sqlite3_free((void *)aCol);
  if( rc!=SQLITE_OK ){
    if( p ){
      fts3DisconnectMethod((sqlite3_vtab *)p);
    }else if( pTokenizer ){
      pTokenizer->pModule->xDestroy(pTokenizer);
    }
................................................................................
    if( !*ppOut ) return SQLITE_NOMEM;
    sqlite3Fts3PutVarint(*ppOut, docid);
  }

  return SQLITE_OK;
}

/*
** An Fts3SegReaderArray is used to store an array of Fts3SegReader objects.
** Elements are added to the array using fts3SegReaderArrayAdd(). 
*/
struct Fts3SegReaderArray {
  int nSegment;                   /* Number of valid entries in apSegment[] */
  int nAlloc;                     /* Allocated size of apSegment[] */
  int nCost;                      /* The cost of executing SegReaderIterate() */
  Fts3SegReader *apSegment[1];    /* Array of seg-reader objects */
};


/*
** Free an Fts3SegReaderArray object. Also free all seg-readers in the
** array (using sqlite3Fts3SegReaderFree()).
*/
static void fts3SegReaderArrayFree(Fts3SegReaderArray *pArray){
  if( pArray ){
    int i;
    for(i=0; i<pArray->nSegment; i++){
      sqlite3Fts3SegReaderFree(pArray->apSegment[i]);
    }
    sqlite3_free(pArray);
  }
}

static int fts3SegReaderArrayAdd(
  Fts3SegReaderArray **ppArray, 
  Fts3SegReader *pNew
){
  Fts3SegReaderArray *pArray = *ppArray;

  if( !pArray || pArray->nAlloc==pArray->nSegment ){
    int nNew = (pArray ? pArray->nAlloc+16 : 16);
    pArray = (Fts3SegReaderArray *)sqlite3_realloc(pArray, 
        sizeof(Fts3SegReaderArray) + (nNew-1) * sizeof(Fts3SegReader*)
    );
    if( !pArray ){
      sqlite3Fts3SegReaderFree(pNew);
      return SQLITE_NOMEM;
    }
    if( nNew==16 ){
      pArray->nSegment = 0;
      pArray->nCost = 0;
    }
    pArray->nAlloc = nNew;
    *ppArray = pArray;
  }

  pArray->apSegment[pArray->nSegment++] = pNew;
  return SQLITE_OK;
}

static int fts3TermSegReaderArray(
  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  Fts3SegReaderArray **ppArray    /* OUT: Allocated seg-reader array */
){
  Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
  int rc;                         /* Return code */
  Fts3SegReaderArray *pArray = 0; /* Array object to build */
  Fts3SegReader *pReader = 0;     /* Seg-reader to add to pArray */ 
  sqlite3_stmt *pStmt = 0;        /* SQL statement to scan %_segdir table */
  int iAge = 0;                   /* Used to assign ages to segments */

  /* Allocate a seg-reader to scan the pending terms, if any. */
  rc = sqlite3Fts3SegReaderPending(p, zTerm, nTerm, isPrefix, &pReader);
  if( rc==SQLITE_OK && pReader ) {
    rc = fts3SegReaderArrayAdd(&pArray, pReader);
  }

  /* Loop through the entire %_segdir table. For each segment, create a
  ** Fts3SegReader to iterate through the subset of the segment leaves
  ** that may contain a term that matches zTerm/nTerm. For non-prefix
  ** searches, this is always a single leaf. For prefix searches, this
  ** may be a contiguous block of leaves.
  */
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts3AllSegdirs(p, &pStmt);
  }
  while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
    Fts3SegReader *pNew = 0;
    int nRoot = sqlite3_column_bytes(pStmt, 4);
    char const *zRoot = sqlite3_column_blob(pStmt, 4);
    if( sqlite3_column_int64(pStmt, 1)==0 ){
      /* The entire segment is stored on the root node (which must be a
      ** leaf). Do not bother inspecting any data in this case, just
      ** create a Fts3SegReader to scan the single leaf. 
      */
      rc = sqlite3Fts3SegReaderNew(iAge, 0, 0, 0, zRoot, nRoot, &pNew);
    }else{
      sqlite3_int64 i1;           /* First leaf that may contain zTerm */
      sqlite3_int64 i2;           /* Final leaf that may contain zTerm */
      rc = fts3SelectLeaf(p, zTerm, nTerm, zRoot, nRoot, &i1, (isPrefix?&i2:0));
      if( isPrefix==0 ) i2 = i1;
      if( rc==SQLITE_OK ){
        rc = sqlite3Fts3SegReaderNew(iAge, i1, i2, 0, 0, 0, &pNew);
      }
    }
    assert( (pNew==0)==(rc!=SQLITE_OK) );

    /* If a new Fts3SegReader was allocated, add it to the array. */
    if( rc==SQLITE_OK ){
      rc = fts3SegReaderArrayAdd(&pArray, pNew);
    }
    if( rc==SQLITE_OK ){
      rc = sqlite3Fts3SegReaderCost(pCsr, pNew, &pArray->nCost);
    }
    iAge++;
  }

  if( rc==SQLITE_DONE ){
    rc = sqlite3_reset(pStmt);
  }else{
    sqlite3_reset(pStmt);
  }
  if( rc!=SQLITE_OK ){
    fts3SegReaderArrayFree(pArray);
    pArray = 0;
  }
  *ppArray = pArray;
  return rc;



}

/*
** This function retreives the doclist for the specified term (or term
** prefix) from the database. 
**
** The returned doclist may be in one of two formats, depending on the 
................................................................................
  Fts3PhraseToken *pTok,          /* Token to query for */
  int iColumn,                    /* Column to query (or -ve for all columns) */
  int isReqPos,                   /* True to include position lists in output */
  int *pnOut,                     /* OUT: Size of buffer at *ppOut */
  char **ppOut                    /* OUT: Malloced result buffer */
){
  int rc;                         /* Return code */
  Fts3SegReaderArray *pArray;     /* Seg-reader array for this term */
  TermSelect tsc;               /* Context object for fts3TermSelectCb() */
  Fts3SegFilter filter;         /* Segment term filter configuration */

  pArray = pTok->pArray;
  memset(&tsc, 0, sizeof(TermSelect));
  tsc.isReqPos = isReqPos;

  filter.flags = FTS3_SEGMENT_IGNORE_EMPTY 
        | (pTok->isPrefix ? FTS3_SEGMENT_PREFIX : 0)
        | (isReqPos ? FTS3_SEGMENT_REQUIRE_POS : 0)
        | (iColumn<p->nColumn ? FTS3_SEGMENT_COLUMN_FILTER : 0);
  filter.iCol = iColumn;
  filter.zTerm = pTok->z;
  filter.nTerm = pTok->n;

  rc = sqlite3Fts3SegReaderIterate(p, pArray->apSegment, pArray->nSegment, 



      &filter, fts3TermSelectCb, (void *)&tsc

  );


  if( rc==SQLITE_OK ){
    rc = fts3TermSelectMerge(&tsc);
  }

  if( rc==SQLITE_OK ){
    *ppOut = tsc.aaOutput[0];
    *pnOut = tsc.anOutput[0];
  }else{
    int i;
    for(i=0; i<SizeofArray(tsc.aaOutput); i++){
      sqlite3_free(tsc.aaOutput[i]);
    }
  }

  fts3SegReaderArrayFree(pArray);
  pTok->pArray = 0;
  return rc;
}

/*
** This function counts the total number of docids in the doclist stored
** in buffer aList[], size nList bytes.
**
................................................................................
  /* If this is an xFilter() evaluation, create a segment-reader for each
  ** phrase token. Or, if this is an xNext() or snippet/offsets/matchinfo
  ** evaluation, only create segment-readers if there are no Fts3DeferredToken
  ** objects attached to the phrase-tokens.
  */
  for(ii=0; ii<pPhrase->nToken; ii++){
    Fts3PhraseToken *pTok = &pPhrase->aToken[ii];
    if( pTok->pArray==0 ){
      if( (pCsr->eEvalmode==FTS3_EVAL_FILTER)
       || (pCsr->eEvalmode==FTS3_EVAL_NEXT && pCsr->pDeferred==0) 
       || (pCsr->eEvalmode==FTS3_EVAL_MATCHINFO && pTok->bFulltext) 
      ){
        rc = fts3TermSegReaderArray(
            pCsr, pTok->z, pTok->n, pTok->isPrefix, &pTok->pArray
        );
        if( rc!=SQLITE_OK ) return rc;
      }
    }
  }

  for(ii=0; ii<pPhrase->nToken; ii++){
................................................................................
      pTok = &pPhrase->aToken[iTok];
    }else{
      int nMinCost = 0x7FFFFFFF;
      int jj;

      /* Find the remaining token with the lowest cost. */
      for(jj=0; jj<pPhrase->nToken; jj++){
        Fts3SegReaderArray *pArray = pPhrase->aToken[jj].pArray;
        if( pArray && pArray->nCost<nMinCost ){
          iTok = jj;
          nMinCost = pArray->nCost;
        }
      }
      pTok = &pPhrase->aToken[iTok];

      /* This branch is taken if it is determined that loading the doclist
      ** for the next token would require more IO than loading all documents
      ** currently identified by doclist pOut/nOut. No further doclists will
................................................................................
        break;
      }
    }

    if( pCsr->eEvalmode==FTS3_EVAL_NEXT && pTok->pDeferred ){
      rc = fts3DeferredTermSelect(pTok->pDeferred, isTermPos, &nList, &pList);
    }else{
      if( pTok->pArray ){
        rc = fts3TermSelect(p, pTok, iCol, isTermPos, &nList, &pList);
      }
      pTok->bFulltext = 1;
    }
    assert( rc!=SQLITE_OK || pCsr->eEvalmode || pTok->pArray==0 );
    if( rc!=SQLITE_OK ) break;

    if( isFirst ){
      pOut = pList;
      nOut = nList;
      if( pCsr->eEvalmode==FTS3_EVAL_FILTER && pPhrase->nToken>1 ){
        nDoc = fts3DoclistCountDocids(1, pOut, nOut);
................................................................................

  if( pExpr->eType==FTSQUERY_PHRASE ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;

    for(ii=0; rc==SQLITE_OK && ii<pPhrase->nToken; ii++){
      Fts3PhraseToken *pTok = &pPhrase->aToken[ii];
      if( pTok->pArray==0 ){
        rc = fts3TermSegReaderArray(
            pCsr, pTok->z, pTok->n, pTok->isPrefix, &pTok->pArray
        );
      }
    }
  }else{ 
    rc = fts3ExprAllocateSegReaders(pCsr, pExpr->pLeft, pnExpr);
    if( rc==SQLITE_OK ){
      rc = fts3ExprAllocateSegReaders(pCsr, pExpr->pRight, pnExpr);
................................................................................
*/
static void fts3ExprFreeSegReaders(Fts3Expr *pExpr){
  if( pExpr ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    if( pPhrase ){
      int kk;
      for(kk=0; kk<pPhrase->nToken; kk++){
        fts3SegReaderArrayFree(pPhrase->aToken[kk].pArray);
        pPhrase->aToken[kk].pArray = 0;
      }
    }
    fts3ExprFreeSegReaders(pExpr->pLeft);
    fts3ExprFreeSegReaders(pExpr->pRight);
  }
}

................................................................................
static int fts3ExprCost(Fts3Expr *pExpr){
  int nCost;                      /* Return value */
  if( pExpr->eType==FTSQUERY_PHRASE ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;
    nCost = 0;
    for(ii=0; ii<pPhrase->nToken; ii++){
      Fts3SegReaderArray *pArray = pPhrase->aToken[ii].pArray;
      if( pArray ){
        nCost += pPhrase->aToken[ii].pArray->nCost;
      }
    }
  }else{
    nCost = fts3ExprCost(pExpr->pLeft) + fts3ExprCost(pExpr->pRight);
  }
  return nCost;
}

................................................................................
  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
  int idxNum,                     /* Strategy index */
  const char *idxStr,             /* Unused */
  int nVal,                       /* Number of elements in apVal */
  sqlite3_value **apVal           /* Arguments for the indexing scheme */
){
  const char *azSql[] = {
    "SELECT * FROM %Q.'%q_content' WHERE docid = ?", /* non-full-table-scan */
    "SELECT * FROM %Q.'%q_content'",                 /* full-table-scan */
  };
  int rc;                         /* Return code */
  char *zSql;                     /* SQL statement used to access %_content */
  Fts3Table *p = (Fts3Table *)pCursor->pVtab;
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  UNUSED_PARAMETER(idxStr);
................................................................................
  }

  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
  ** statement loops through all rows of the %_content table. For a
  ** full-text query or docid lookup, the statement retrieves a single
  ** row by docid.
  */
  zSql = sqlite3_mprintf(azSql[idxNum==FTS3_FULLSCAN_SEARCH], p->zDb, p->zName);

  if( !zSql ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
    sqlite3_free(zSql);
  }
  if( rc==SQLITE_OK && idxNum==FTS3_DOCID_SEARCH ){
................................................................................
  const sqlite3_tokenizer_module *pPorter = 0;

#ifdef SQLITE_ENABLE_ICU
  const sqlite3_tokenizer_module *pIcu = 0;
  sqlite3Fts3IcuTokenizerModule(&pIcu);
#endif




  sqlite3Fts3SimpleTokenizerModule(&pSimple);
  sqlite3Fts3PorterTokenizerModule(&pPorter);

  /* Allocate and initialise the hash-table used to store tokenizers. */
  pHash = sqlite3_malloc(sizeof(Fts3Hash));
  if( !pHash ){
    rc = SQLITE_NOMEM;
................................................................................
  return sqlite3Fts3Init(db);
}
#endif

#endif

/************** End of fts3.c ************************************************/






















































































































































































































































































































































































































































































/************** Begin file fts3_expr.c ***************************************/
/*
** 2008 Nov 28
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
................................................................................
/* 0  */  "DELETE FROM %Q.'%q_content' WHERE rowid = ?",
/* 1  */  "SELECT NOT EXISTS(SELECT docid FROM %Q.'%q_content' WHERE rowid!=?)",
/* 2  */  "DELETE FROM %Q.'%q_content'",
/* 3  */  "DELETE FROM %Q.'%q_segments'",
/* 4  */  "DELETE FROM %Q.'%q_segdir'",
/* 5  */  "DELETE FROM %Q.'%q_docsize'",
/* 6  */  "DELETE FROM %Q.'%q_stat'",
/* 7  */  "SELECT * FROM %Q.'%q_content' WHERE rowid=?",
/* 8  */  "SELECT (SELECT max(idx) FROM %Q.'%q_segdir' WHERE level = ?) + 1",
/* 9  */  "INSERT INTO %Q.'%q_segments'(blockid, block) VALUES(?, ?)",
/* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
/* 11 */  "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",

          /* Return segments in order from oldest to newest.*/ 
/* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
................................................................................
            "FROM %Q.'%q_segdir' ORDER BY level DESC, idx ASC",

/* 14 */  "SELECT count(*) FROM %Q.'%q_segdir' WHERE level = ?",
/* 15 */  "SELECT count(*), max(level) FROM %Q.'%q_segdir'",

/* 16 */  "DELETE FROM %Q.'%q_segdir' WHERE level = ?",
/* 17 */  "DELETE FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ?",
/* 18 */  "INSERT INTO %Q.'%q_content' VALUES(%z)",
/* 19 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
/* 20 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
/* 21 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=0",
/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(0,?)",
  };
  int rc = SQLITE_OK;
................................................................................
  assert( SizeofArray(azSql)==SizeofArray(p->aStmt) );
  assert( eStmt<SizeofArray(azSql) && eStmt>=0 );
  
  pStmt = p->aStmt[eStmt];
  if( !pStmt ){
    char *zSql;
    if( eStmt==SQL_CONTENT_INSERT ){
      int i;                      /* Iterator variable */  
      char *zVarlist;             /* The "?, ?, ..." string */
      zVarlist = (char *)sqlite3_malloc(2*p->nColumn+2);
      if( !zVarlist ){
        *pp = 0;
        return SQLITE_NOMEM;
      }
      zVarlist[0] = '?';
      zVarlist[p->nColumn*2+1] = '\0';
      for(i=1; i<=p->nColumn; i++){
        zVarlist[i*2-1] = ',';
        zVarlist[i*2] = '?';
      }
      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName, zVarlist);


    }else{
      zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName);
    }
    if( !zSql ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, NULL);
................................................................................

  rc = fts3SqlStmt(pTab, eStmt, &pStmt, 0);
  if( rc==SQLITE_OK ){
    if( eStmt==SQL_SELECT_DOCSIZE ){
      sqlite3_bind_int64(pStmt, 1, iDocid);
    }
    rc = sqlite3_step(pStmt);
    if( rc!=SQLITE_ROW ){
      rc = sqlite3_reset(pStmt);
      if( rc==SQLITE_OK ) rc = SQLITE_CORRUPT;
      pStmt = 0;
    }else{
      rc = SQLITE_OK;
    }
  }
................................................................................
**
**   0: idx
**   1: start_block
**   2: leaves_end_block
**   3: end_block
**   4: root
*/
SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(Fts3Table *p, sqlite3_stmt **ppStmt){



  return fts3SqlStmt(p, SQL_SELECT_ALL_LEVEL, ppStmt, 0);






}


/*
** Append a single varint to a PendingList buffer. SQLITE_OK is returned
** if successful, or an SQLite error code otherwise.
**
................................................................................
      ** the table. The following nCol varints contain the total amount of
      ** data stored in all rows of each column of the table, from left
      ** to right.
      */
      sqlite3_stmt *pStmt;
      sqlite3_int64 nDoc = 0;
      sqlite3_int64 nByte = 0;

      const char *a;

      rc = sqlite3Fts3SelectDoctotal(p, &pStmt);
      if( rc ) return rc;
      a = sqlite3_column_blob(pStmt, 0);
      if( a ){

        const char *pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
        a += sqlite3Fts3GetVarint(a, &nDoc);
        while( a<pEnd ){
          a += sqlite3Fts3GetVarint(a, &nByte);
        }
      }
      if( nDoc==0 || nByte==0 ){
        sqlite3_reset(pStmt);
        return SQLITE_CORRUPT;
      }

      pCsr->nRowAvg = (int)(((nByte / nDoc) + pgsz) / pgsz);
................................................................................
  if( isPrefix ){
    sqlite3_free(aElem);
  }
  *ppReader = pReader;
  return rc;
}


/*
** The second argument to this function is expected to be a statement of
** the form:
**
**   SELECT 
**     idx,                  -- col 0
**     start_block,          -- col 1
**     leaves_end_block,     -- col 2
**     end_block,            -- col 3
**     root                  -- col 4
**   FROM %_segdir ...
**
** This function allocates and initializes a Fts3SegReader structure to
** iterate through the terms stored in the segment identified by the
** current row that pStmt is pointing to. 
**
** If successful, the Fts3SegReader is left pointing to the first term
** in the segment and SQLITE_OK is returned. Otherwise, an SQLite error
** code is returned.
*/
static int fts3SegReaderNew(
  sqlite3_stmt *pStmt,            /* See above */
  int iAge,                       /* Segment "age". */
  Fts3SegReader **ppReader        /* OUT: Allocated Fts3SegReader */
){
  return sqlite3Fts3SegReaderNew(iAge, 
      sqlite3_column_int64(pStmt, 1),
      sqlite3_column_int64(pStmt, 2),
      sqlite3_column_int64(pStmt, 3),
      sqlite3_column_blob(pStmt, 4),
      sqlite3_column_bytes(pStmt, 4),
      ppReader
  );
}

/*
** Compare the entries pointed to by two Fts3SegReader structures. 
** Comparison is as follows:
**
**   1) EOF is greater than not EOF.
**
**   2) The current terms (if any) are compared using memcmp(). If one
................................................................................
      *pisEmpty = sqlite3_column_int(pStmt, 0);
    }
    rc = sqlite3_reset(pStmt);
  }
  return rc;
}

/*
** Set *pnSegment to the number of segments of level iLevel in the database.
**
** Return SQLITE_OK if successful, or an SQLite error code if not.
*/
static int fts3SegmentCount(Fts3Table *p, int iLevel, int *pnSegment){
  sqlite3_stmt *pStmt;
  int rc;

  assert( iLevel>=0 );
  rc = fts3SqlStmt(p, SQL_SELECT_LEVEL_COUNT, &pStmt, 0);
  if( rc!=SQLITE_OK ) return rc;
  sqlite3_bind_int(pStmt, 1, iLevel);
  if( SQLITE_ROW==sqlite3_step(pStmt) ){
    *pnSegment = sqlite3_column_int(pStmt, 0);
  }
  return sqlite3_reset(pStmt);
}

/*
** Set *pnSegment to the total number of segments in the database. Set
** *pnMax to the largest segment level in the database (segment levels
** are stored in the 'level' column of the %_segdir table).
**
** Return SQLITE_OK if successful, or an SQLite error code if not.
*/
................................................................................
      rc = sqlite3_reset(pDelete);
    }
  }
  if( rc!=SQLITE_OK ){
    return rc;
  }






  if( iLevel>=0 ){
    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_BY_LEVEL, &pDelete, 0);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int(pDelete, 1, iLevel);
      sqlite3_step(pDelete);
      rc = sqlite3_reset(pDelete);
    }
  }else{
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGDIR, 0);
  }

  return rc;
}

/*
** When this function is called, buffer *ppList (size *pnList bytes) contains 
................................................................................
    p += sqlite3Fts3GetVarint32(p, &iCurrent);
  }

  *ppList = pList;
  *pnList = nList;
}

/*
** sqlite3Fts3SegReaderIterate() callback used when merging multiple 
** segments to create a single, larger segment.
*/
static int fts3MergeCallback(
  Fts3Table *p,                   /* FTS3 Virtual table handle */
  void *pContext,                 /* Pointer to SegmentWriter* to write with */
  char *zTerm,                    /* Term to write to the db */
  int nTerm,                      /* Number of bytes in zTerm */
  char *aDoclist,                 /* Doclist associated with zTerm */
  int nDoclist                    /* Number of bytes in doclist */
){
  SegmentWriter **ppW = (SegmentWriter **)pContext;
  return fts3SegWriterAdd(p, ppW, 1, zTerm, nTerm, aDoclist, nDoclist);
}

/*
** sqlite3Fts3SegReaderIterate() callback used when flushing the contents
** of the pending-terms hash table to the database.
*/
static int fts3FlushCallback(
  Fts3Table *p,                   /* FTS3 Virtual table handle */
  void *pContext,                 /* Pointer to SegmentWriter* to write with */
  char *zTerm,                    /* Term to write to the db */
  int nTerm,                      /* Number of bytes in zTerm */
  char *aDoclist,                 /* Doclist associated with zTerm */
  int nDoclist                    /* Number of bytes in doclist */
){
  SegmentWriter **ppW = (SegmentWriter **)pContext;
  return fts3SegWriterAdd(p, ppW, 0, zTerm, nTerm, aDoclist, nDoclist);
}

/*
** This function is used to iterate through a contiguous set of terms 
** stored in the full-text index. It merges data contained in one or 
** more segments to support this.
**
** The second argument is passed an array of pointers to SegReader objects
** allocated with sqlite3Fts3SegReaderNew(). This function merges the range 
** of terms selected by each SegReader. If a single term is present in
** more than one segment, the associated doclists are merged. For each
** term and (possibly merged) doclist in the merged range, the callback
** function xFunc is invoked with its arguments set as follows.
**
**   arg 0: Copy of 'p' parameter passed to this function
**   arg 1: Copy of 'pContext' parameter passed to this function
**   arg 2: Pointer to buffer containing term
**   arg 3: Size of arg 2 buffer in bytes
**   arg 4: Pointer to buffer containing doclist
**   arg 5: Size of arg 2 buffer in bytes
**
** The 4th argument to this function is a pointer to a structure of type
** Fts3SegFilter, defined in fts3Int.h. The contents of this structure
** further restrict the range of terms that callbacks are made for and
** modify the behaviour of this function. See comments above structure
** definition for details.
*/
SQLITE_PRIVATE int sqlite3Fts3SegReaderIterate(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3SegReader **apSegment,      /* Array of Fts3SegReader objects */
  int nSegment,                   /* Size of apSegment array */

  Fts3SegFilter *pFilter,         /* Restrictions on range of iteration */
  int (*xFunc)(Fts3Table *, void *, char *, int, char *, int),  /* Callback */
  void *pContext                  /* Callback context (2nd argument) */
){
  int i;                          /* Iterator variable */
  char *aBuffer = 0;              /* Buffer to merge doclists in */
  int nAlloc = 0;                 /* Allocated size of aBuffer buffer */
  int rc = SQLITE_OK;             /* Return code */


  int isIgnoreEmpty =  (pFilter->flags & FTS3_SEGMENT_IGNORE_EMPTY);
  int isRequirePos =   (pFilter->flags & FTS3_SEGMENT_REQUIRE_POS);
  int isColFilter =    (pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
  int isPrefix =       (pFilter->flags & FTS3_SEGMENT_PREFIX);

  /* If there are zero segments, this function is a no-op. This scenario
  ** comes about only when reading from an empty database.
  */
  if( nSegment==0 ) goto finished;



  /* If the Fts3SegFilter defines a specific term (or term prefix) to search 
  ** for, then advance each segment iterator until it points to a term of
  ** equal or greater value than the specified term. This prevents many
  ** unnecessary merge/sort operations for the case where single segment
  ** b-tree leaf nodes contain more than one term.
  */
  for(i=0; i<nSegment; i++){
    int nTerm = pFilter->nTerm;
    const char *zTerm = pFilter->zTerm;
    Fts3SegReader *pSeg = apSegment[i];
    do {
      rc = fts3SegReaderNext(p, pSeg);
      if( rc!=SQLITE_OK ) goto finished;
    }while( zTerm && fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 );
  }



































  fts3SegReaderSort(apSegment, nSegment, nSegment, fts3SegReaderCmp);




  while( apSegment[0]->aNode ){

    int nTerm = apSegment[0]->nTerm;
    char *zTerm = apSegment[0]->zTerm;
    int nMerge = 1;

    /* If this is a prefix-search, and if the term that apSegment[0] points
    ** to does not share a suffix with pFilter->zTerm/nTerm, then all 
    ** required callbacks have been made. In this case exit early.
    **
    ** Similarly, if this is a search for an exact match, and the first term
    ** of segment apSegment[0] is not a match, exit early.
    */
    if( pFilter->zTerm ){
      if( nTerm<pFilter->nTerm 
       || (!isPrefix && nTerm>pFilter->nTerm)
       || memcmp(zTerm, pFilter->zTerm, pFilter->nTerm) 
    ){
        goto finished;
      }
    }


    while( nMerge<nSegment 
        && apSegment[nMerge]->aNode
        && apSegment[nMerge]->nTerm==nTerm 
        && 0==memcmp(zTerm, apSegment[nMerge]->zTerm, nTerm)
    ){
      nMerge++;
    }

    assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );
    if( nMerge==1 && !isIgnoreEmpty ){
      Fts3SegReader *p0 = apSegment[0];
      rc = xFunc(p, pContext, zTerm, nTerm, p0->aDoclist, p0->nDoclist);
      if( rc!=SQLITE_OK ) goto finished;
    }else{
      int nDoclist = 0;           /* Size of doclist */
      sqlite3_int64 iPrev = 0;    /* Previous docid stored in doclist */

      /* The current term of the first nMerge entries in the array
      ** of Fts3SegReader objects is the same. The doclists must be merged
      ** and a single term added to the new segment.
      */
      for(i=0; i<nMerge; i++){
        fts3SegReaderFirstDocid(apSegment[i]);
      }
      fts3SegReaderSort(apSegment, nMerge, nMerge, fts3SegReaderDoclistCmp);
      while( apSegment[0]->pOffsetList ){
        int j;                    /* Number of segments that share a docid */
................................................................................

        if( isColFilter ){
          fts3ColumnFilter(pFilter->iCol, &pList, &nList);
        }

        if( !isIgnoreEmpty || nList>0 ){
          nByte = sqlite3Fts3VarintLen(iDocid-iPrev) + (isRequirePos?nList+1:0);
          if( nDoclist+nByte>nAlloc ){
            char *aNew;
            nAlloc = (nDoclist+nByte)*2;
            aNew = sqlite3_realloc(aBuffer, nAlloc);
            if( !aNew ){
              rc = SQLITE_NOMEM;
              goto finished;
            }
            aBuffer = aNew;
          }
          nDoclist += sqlite3Fts3PutVarint(&aBuffer[nDoclist], iDocid-iPrev);


          iPrev = iDocid;
          if( isRequirePos ){
            memcpy(&aBuffer[nDoclist], pList, nList);
            nDoclist += nList;
            aBuffer[nDoclist++] = '\0';
          }
        }

        fts3SegReaderSort(apSegment, nMerge, j, fts3SegReaderDoclistCmp);
      }

      if( nDoclist>0 ){

        rc = xFunc(p, pContext, zTerm, nTerm, aBuffer, nDoclist);
        if( rc!=SQLITE_OK ) goto finished;
      }
    }



    /* If there is a term specified to filter on, and this is not a prefix
    ** search, return now. The callback that corresponds to the required
    ** term (if such a term exists in the index) has already been made.
    */
    if( pFilter->zTerm && !isPrefix ){
      goto finished;
    }






    for(i=0; i<nMerge; i++){
      rc = fts3SegReaderNext(p, apSegment[i]);
      if( rc!=SQLITE_OK ) goto finished;

    }
    fts3SegReaderSort(apSegment, nSegment, nMerge, fts3SegReaderCmp);


  }




 finished:
  sqlite3_free(aBuffer);
  return rc;
}

/*
** Merge all level iLevel segments in the database into a single 
** iLevel+1 segment. Or, if iLevel<0, merge all segments into a
** single segment with a level equal to the numerically largest level 
** currently present in the database.
................................................................................
**
** If this function is called with iLevel<0, but there is only one
** segment in the database, SQLITE_DONE is returned immediately. 
** Otherwise, if successful, SQLITE_OK is returned. If an error occurs, 
** an SQLite error code is returned.
*/
static int fts3SegmentMerge(Fts3Table *p, int iLevel){
  int i;                          /* Iterator variable */
  int rc;                         /* Return code */
  int iIdx;                       /* Index of new segment */
  int iNewLevel = 0;              /* Level to create new segment at */
  sqlite3_stmt *pStmt = 0;
  SegmentWriter *pWriter = 0;
  int nSegment = 0;               /* Number of segments being merged */
  Fts3SegReader **apSegment = 0;  /* Array of Segment iterators */
  Fts3SegReader *pPending = 0;    /* Iterator for pending-terms */
  Fts3SegFilter filter;           /* Segment term filter condition */

  if( iLevel<0 ){
    /* This call is to merge all segments in the database to a single
    ** segment. The level of the new segment is equal to the the numerically 
    ** greatest segment level currently present in the database. The index
    ** of the new segment is always 0.
    */
    iIdx = 0;
    rc = sqlite3Fts3SegReaderPending(p, 0, 0, 1, &pPending);
    if( rc!=SQLITE_OK ) goto finished;
    rc = fts3SegmentCountMax(p, &nSegment, &iNewLevel);
    if( rc!=SQLITE_OK ) goto finished;
    nSegment += (pPending!=0);
    if( nSegment<=1 ){
      return SQLITE_DONE;

    }

  }else{
    /* This call is to merge all segments at level iLevel. Find the next
    ** available segment index at level iLevel+1. The call to
    ** fts3AllocateSegdirIdx() will merge the segments at level iLevel+1 to 
    ** a single iLevel+2 segment if necessary.
    */
    iNewLevel = iLevel+1;
    rc = fts3AllocateSegdirIdx(p, iNewLevel, &iIdx);
    if( rc!=SQLITE_OK ) goto finished;
    rc = fts3SegmentCount(p, iLevel, &nSegment);
    if( rc!=SQLITE_OK ) goto finished;
  }

  assert( nSegment>0 );
  assert( iNewLevel>=0 );

  /* Allocate space for an array of pointers to segment iterators. */
  apSegment = (Fts3SegReader**)sqlite3_malloc(sizeof(Fts3SegReader *)*nSegment);
  if( !apSegment ){
    rc = SQLITE_NOMEM;
    goto finished;
  }
  memset(apSegment, 0, sizeof(Fts3SegReader *)*nSegment);



  /* Allocate a Fts3SegReader structure for each segment being merged. A 
  ** Fts3SegReader stores the state data required to iterate through all 
  ** entries on all leaves of a single segment. 
  */
  assert( SQL_SELECT_LEVEL+1==SQL_SELECT_ALL_LEVEL);
  rc = fts3SqlStmt(p, SQL_SELECT_LEVEL+(iLevel<0), &pStmt, 0);
  if( rc!=SQLITE_OK ) goto finished;
  sqlite3_bind_int(pStmt, 1, iLevel);
  for(i=0; SQLITE_ROW==(sqlite3_step(pStmt)); i++){
    rc = fts3SegReaderNew(pStmt, i, &apSegment[i]);

    if( rc!=SQLITE_OK ){
      goto finished;
    }
  }
  rc = sqlite3_reset(pStmt);
  if( pPending ){
    apSegment[i] = pPending;
    pPending = 0;
  }
  pStmt = 0;
  if( rc!=SQLITE_OK ) goto finished;



  memset(&filter, 0, sizeof(Fts3SegFilter));
  filter.flags = FTS3_SEGMENT_REQUIRE_POS;
  filter.flags |= (iLevel<0 ? FTS3_SEGMENT_IGNORE_EMPTY : 0);
  rc = sqlite3Fts3SegReaderIterate(p, apSegment, nSegment,
      &filter, fts3MergeCallback, (void *)&pWriter
  );
  if( rc!=SQLITE_OK ) goto finished;


  rc = fts3DeleteSegdir(p, iLevel, apSegment, nSegment);
  if( rc==SQLITE_OK ){
    rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);
  }

 finished:
  fts3SegWriterFree(pWriter);
  if( apSegment ){
    for(i=0; i<nSegment; i++){
      sqlite3Fts3SegReaderFree(apSegment[i]);
    }
    sqlite3_free(apSegment);
  }
  sqlite3Fts3SegReaderFree(pPending);
  sqlite3_reset(pStmt);
  return rc;
}


/* 
** Flush the contents of pendingTerms to a level 0 segment.
*/
SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *p){
  int rc;                         /* Return Code */
  int idx;                        /* Index of new segment created */
  SegmentWriter *pWriter = 0;     /* Used to write the segment */
  Fts3SegReader *pReader = 0;     /* Used to iterate through the hash table */

  /* Allocate a SegReader object to iterate through the contents of the
  ** pending-terms table. If an error occurs, or if there are no terms
  ** in the pending-terms table, return immediately.
  */
  rc = sqlite3Fts3SegReaderPending(p, 0, 0, 1, &pReader);
  if( rc!=SQLITE_OK || pReader==0 ){
    return rc;
  }

  /* Determine the next index at level 0. If level 0 is already full, this
  ** call may merge all existing level 0 segments into a single level 1
  ** segment.
  */
  rc = fts3AllocateSegdirIdx(p, 0, &idx);

  /* If no errors have occured, iterate through the contents of the 
  ** pending-terms hash table using the Fts3SegReader iterator. The callback
  ** writes each term (along with its doclist) to the database via the
  ** SegmentWriter handle pWriter.
  */
  if( rc==SQLITE_OK ){
    void *c = (void *)&pWriter;   /* SegReaderIterate() callback context */
    Fts3SegFilter f;              /* SegReaderIterate() parameters */

    memset(&f, 0, sizeof(Fts3SegFilter));
    f.flags = FTS3_SEGMENT_REQUIRE_POS;
    rc = sqlite3Fts3SegReaderIterate(p, &pReader, 1, &f, fts3FlushCallback, c);
  }
  assert( pWriter || rc!=SQLITE_OK );

  /* If no errors have occured, flush the SegmentWriter object to the
  ** database. Then delete the SegmentWriter and Fts3SegReader objects
  ** allocated by this function.
  */
  if( rc==SQLITE_OK ){
    rc = fts3SegWriterFlush(p, pWriter, 0, idx);
  }
  fts3SegWriterFree(pWriter);
  sqlite3Fts3SegReaderFree(pReader);

  if( rc==SQLITE_OK ){
    sqlite3Fts3PendingTermsClear(p);
  }
  return rc;
}

/*
** Encode N integers as varints into a blob.
*/
static void fts3EncodeIntArray(
  int N,             /* The number of integers to encode */
................................................................................
  int rc;                         /* Return Code */
  const char *zVal = (const char *)sqlite3_value_text(pVal);
  int nVal = sqlite3_value_bytes(pVal);

  if( !zVal ){
    return SQLITE_NOMEM;
  }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
    rc = fts3SegmentMerge(p, -1);
    if( rc==SQLITE_DONE ){
      rc = SQLITE_OK;
    }else{
      sqlite3Fts3PendingTermsClear(p);
    }
#ifdef SQLITE_TEST
  }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
................................................................................
** merge all segments in the database (including the new segment, if 
** there was any data to flush) into a single segment. 
*/
SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *p){
  int rc;
  rc = sqlite3_exec(p->db, "SAVEPOINT fts3", 0, 0, 0);
  if( rc==SQLITE_OK ){
    rc = fts3SegmentMerge(p, -1);
    if( rc==SQLITE_OK ){
      rc = sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
      if( rc==SQLITE_OK ){
        sqlite3Fts3PendingTermsClear(p);
      }
    }else{
      sqlite3_exec(p->db, "ROLLBACK TO fts3", 0, 0, 0);
................................................................................
*/
static int fts3ExprLocalHitsCb(
  Fts3Expr *pExpr,                /* Phrase expression node */
  int iPhrase,                    /* Phrase number */
  void *pCtx                      /* Pointer to MatchInfo structure */
){
  MatchInfo *p = (MatchInfo *)pCtx;





  if( pExpr->aDoclist ){
    char *pCsr;
    int iStart = iPhrase * p->nCol * 3;
    int i;

    for(i=0; i<p->nCol; i++) p->aMatchinfo[iStart+i*3] = 0;

    pCsr = sqlite3Fts3FindPositions(pExpr, p->pCursor->iPrevId, -1);
    if( pCsr ){
      fts3LoadColumnlistCounts(&pCsr, &p->aMatchinfo[iStart], 0);
    }
  }

................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }
  pStmt = *ppStmt;
  assert( sqlite3_data_count(pStmt)==1 );

  a = sqlite3_column_blob(pStmt, 0);
  a += sqlite3Fts3GetVarint(a, &nDoc);

  *pnDoc = (u32)nDoc;

  if( paLen ) *paLen = a;
  return SQLITE_OK;
}

/*
................................................................................
          sqlite3_int64 nDoc;     /* Number of rows in table */
          const char *a;          /* Aggregate column length array */

          rc = fts3MatchinfoSelectDoctotal(pTab, &pSelect, &nDoc, &a);
          if( rc==SQLITE_OK ){
            int iCol;
            for(iCol=0; iCol<pInfo->nCol; iCol++){

              sqlite3_int64 nToken;
              a += sqlite3Fts3GetVarint(a, &nToken);
              pInfo->aMatchinfo[iCol] = (u32)(((u32)(nToken&0xffffffff)+nDoc/2)/nDoc);

            }
          }
        }
        break;

      case FTS3_MATCHINFO_LENGTH: {
        sqlite3_stmt *pSelectDocsize = 0;
................................................................................
    if( argc>0 ){
      pCsr->aConstraint = sqlite3_malloc(sizeof(RtreeConstraint)*argc);
      pCsr->nConstraint = argc;
      if( !pCsr->aConstraint ){
        rc = SQLITE_NOMEM;
      }else{
        memset(pCsr->aConstraint, 0, sizeof(RtreeConstraint)*argc);
        assert( (idxStr==0 && argc==0) || strlen(idxStr)==argc*2 );
        for(ii=0; ii<argc; ii++){
          RtreeConstraint *p = &pCsr->aConstraint[ii];
          p->op = idxStr[ii*2];
          p->iCoord = idxStr[ii*2+1]-'a';
          if( p->op==RTREE_MATCH ){
            /* A MATCH operator. The right-hand-side must be a blob that
            ** can be cast into an RtreeMatchArg object. One created using
................................................................................
**
** The second of each pair of bytes identifies the coordinate column
** to which the constraint applies. The leftmost coordinate column
** is 'a', the second from the left 'b' etc.
*/
static int rtreeBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
  int rc = SQLITE_OK;
  int ii, cCol;

  int iIdx = 0;
  char zIdxStr[RTREE_MAX_DIMENSIONS*8+1];
  memset(zIdxStr, 0, sizeof(zIdxStr));
  UNUSED_PARAMETER(tab);

  assert( pIdxInfo->idxStr==0 );
  for(ii=0; ii<pIdxInfo->nConstraint; ii++){
    struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[ii];

    if( p->usable && p->iColumn==0 && p->op==SQLITE_INDEX_CONSTRAINT_EQ ){
      /* We have an equality constraint on the rowid. Use strategy 1. */
      int jj;
      for(jj=0; jj<ii; jj++){
        pIdxInfo->aConstraintUsage[jj].argvIndex = 0;
................................................................................
      ** sqlite uses an internal cost of 0.0).
      */ 
      pIdxInfo->estimatedCost = 10.0;
      return SQLITE_OK;
    }

    if( p->usable && (p->iColumn>0 || p->op==SQLITE_INDEX_CONSTRAINT_MATCH) ){
      int j, opmsk;
      static const unsigned char compatible[] = { 0, 0, 1, 1, 2, 2 };
      u8 op = 0;
      switch( p->op ){
        case SQLITE_INDEX_CONSTRAINT_EQ: op = RTREE_EQ; break;
        case SQLITE_INDEX_CONSTRAINT_GT: op = RTREE_GT; break;
        case SQLITE_INDEX_CONSTRAINT_LE: op = RTREE_LE; break;
        case SQLITE_INDEX_CONSTRAINT_LT: op = RTREE_LT; break;
        case SQLITE_INDEX_CONSTRAINT_GE: op = RTREE_GE; break;
        default:
          assert( p->op==SQLITE_INDEX_CONSTRAINT_MATCH );
          op = RTREE_MATCH; 
          break;
      }
      assert( op!=0 );

      /* Make sure this particular constraint has not been used before.
      ** If it has been used before, ignore it.
      **
      ** A <= or < can be used if there is a prior >= or >.
      ** A >= or > can be used if there is a prior < or <=.
      ** A <= or < is disqualified if there is a prior <=, <, or ==.
      ** A >= or > is disqualified if there is a prior >=, >, or ==.
      ** A == is disqualifed if there is any prior constraint.
      */
      assert( compatible[RTREE_EQ & 7]==0 );
      assert( compatible[RTREE_LT & 7]==1 );
      assert( compatible[RTREE_LE & 7]==1 );
      assert( compatible[RTREE_GT & 7]==2 );
      assert( compatible[RTREE_GE & 7]==2 );
      cCol = p->iColumn - 1 + 'a';
      opmsk = compatible[op & 7];
      for(j=0; j<iIdx; j+=2){
        if( zIdxStr[j+1]==cCol && (compatible[zIdxStr[j] & 7] & opmsk)!=0 ){
          op = 0;
          break;
        }
      }
      if( op ){
        assert( iIdx<sizeof(zIdxStr)-1 );
        zIdxStr[iIdx++] = op;
        zIdxStr[iIdx++] = cCol;
        pIdxInfo->aConstraintUsage[ii].argvIndex = (iIdx/2);
        pIdxInfo->aConstraintUsage[ii].omit = 1;
      }
    }
  }

  pIdxInfo->idxNum = 2;
  pIdxInfo->needToFreeIdxStr = 1;
  if( iIdx>0 && 0==(pIdxInfo->idxStr = sqlite3_mprintf("%s", zIdxStr)) ){
    return SQLITE_NOMEM;
................................................................................
  for(ii=0; ii<NCELL(&node); ii++){
    char zCell[512];
    int nCell = 0;
    RtreeCell cell;
    int jj;

    nodeGetCell(&tree, &node, ii, &cell);
    sqlite3_snprintf(512-nCell,&zCell[nCell],"%d", cell.iRowid);
    nCell = strlen(zCell);
    for(jj=0; jj<tree.nDim*2; jj++){
      sqlite3_snprintf(512-nCell,&zCell[nCell]," %f",(double)cell.aCoord[jj].f);
      nCell = strlen(zCell);
    }

    if( zText ){
................................................................................
**     uregex_close()
*/
static void icuRegexpFunc(sqlite3_context *p, int nArg, sqlite3_value **apArg){
  UErrorCode status = U_ZERO_ERROR;
  URegularExpression *pExpr;
  UBool res;
  const UChar *zString = sqlite3_value_text16(apArg[1]);



  /* If the left hand side of the regexp operator is NULL, 
  ** then the result is also NULL. 
  */
  if( !zString ){
    return;
  }
................................................................................

    {"icu_load_collation",  2, SQLITE_UTF8, (void*)db, icuLoadCollation},
  };

  int rc = SQLITE_OK;
  int i;

  for(i=0; rc==SQLITE_OK && i<(sizeof(scalars)/sizeof(struct IcuScalar)); i++){
    struct IcuScalar *p = &scalars[i];
    rc = sqlite3_create_function(
        db, p->zName, p->nArg, p->enc, p->pContext, p->xFunc, 0, 0
    );
  }

  return rc;

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.7.6.  By combining all the individual C code files into this 
** single large file, the entire code can be compiled as a single translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% or more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other
** programs, you need this file and the "sqlite3.h" header file that defines
................................................................................
*/
#ifndef SQLITE_DEFAULT_WAL_AUTOCHECKPOINT
# define SQLITE_DEFAULT_WAL_AUTOCHECKPOINT  1000
#endif

/*
** The maximum number of attached databases.  This must be between 0
** and 62.  The upper bound on 62 is because a 64-bit integer bitmap
** is used internally to track attached databases.
*/
#ifndef SQLITE_MAX_ATTACHED
# define SQLITE_MAX_ATTACHED 10
#endif


................................................................................
** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.6"
#define SQLITE_VERSION_NUMBER 3007006
#define SQLITE_SOURCE_ID      "2011-04-11 18:35:09 51029d8430d2dbc782f161577d47e3dd11c4e4d7"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */
#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_WAL              0x00080000  /* VFS only */

/* Reserved:                         0x00F00000 */

/*
** CAPI3REF: Device Characteristics
**
** The xDeviceCharacteristics method of the [sqlite3_io_methods]
** object returns an integer which is a vector of the these
** bit values expressing I/O characteristics of the mass storage
** device that holds the file that the [sqlite3_io_methods]
................................................................................
** ^(The [SQLITE_FCNTL_SYNC_OMITTED] opcode is generated internally by
** SQLite and sent to all VFSes in place of a call to the xSync method
** when the database connection has [PRAGMA synchronous] set to OFF.)^
** Some specialized VFSes need this signal in order to operate correctly
** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most 
** VFSes do not need this signal and should silently ignore this opcode.
** Applications should not call [sqlite3_file_control()] with this
** opcode as doing so may disrupt the operation of the specialized VFSes
** that do require it.  
*/
#define SQLITE_FCNTL_LOCKSTATE        1
#define SQLITE_GET_LOCKPROXYFILE      2
#define SQLITE_SET_LOCKPROXYFILE      3
#define SQLITE_LAST_ERRNO             4
#define SQLITE_FCNTL_SIZE_HINT        5
................................................................................
** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
** Day Number multipled by 86400000 (the number of milliseconds in 
** a 24-hour day).  
** ^SQLite will use the xCurrentTimeInt64() method to get the current
** date and time if that method is available (if iVersion is 2 or 
** greater and the function pointer is not NULL) and will fall back
** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
**
** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
** are not used by the SQLite core.  These optional interfaces are provided
** by some VFSes to facilitate testing of the VFS code. By overriding 
** system calls with functions under its control, a test program can
** simulate faults and error conditions that would otherwise be difficult
** or impossible to induce.  The set of system calls that can be overridden
** varies from one VFS to another, and from one version of the same VFS to the
** next.  Applications that use these interfaces must be prepared for any
** or all of these interfaces to be NULL or for their behavior to change
** from one release to the next.  Applications must not attempt to access
** any of these methods if the iVersion of the VFS is less than 3.
*/
typedef struct sqlite3_vfs sqlite3_vfs;
typedef void (*sqlite3_syscall_ptr)(void);
struct sqlite3_vfs {
  int iVersion;            /* Structure version number (currently 3) */
  int szOsFile;            /* Size of subclassed sqlite3_file */
  int mxPathname;          /* Maximum file pathname length */
  sqlite3_vfs *pNext;      /* Next registered VFS */
  const char *zName;       /* Name of this virtual file system */
  void *pAppData;          /* Pointer to application-specific data */
  int (*xOpen)(sqlite3_vfs*, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
................................................................................
  /*
  ** The methods above are in version 1 of the sqlite_vfs object
  ** definition.  Those that follow are added in version 2 or later
  */
  int (*xCurrentTimeInt64)(sqlite3_vfs*, sqlite3_int64*);
  /*
  ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
  ** Those below are for version 3 and greater.
  */
  int (*xSetSystemCall)(sqlite3_vfs*, const char *zName, sqlite3_syscall_ptr);
  sqlite3_syscall_ptr (*xGetSystemCall)(sqlite3_vfs*, const char *zName);
  const char *(*xNextSystemCall)(sqlite3_vfs*, const char *zName);
  /*
  ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
  ** New fields may be appended in figure versions.  The iVersion
  ** value will increment whenever this happens. 
  */
};

/*
** CAPI3REF: Flags for the xAccess VFS method
................................................................................

/*
** CAPI3REF: Configure database connections
**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).



**
** The second argument to sqlite3_db_config(D,V,...)  is the

** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code 
** that indicates what aspect of the [database connection] is being configured.



** Subsequent arguments vary depending on the configuration verb.
**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);

/*
................................................................................
** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
** allocation statistics are disabled by default.
** </dd>
**
** <dt>SQLITE_CONFIG_SCRATCH</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** scratch memory.  There are three arguments:  A pointer an 8-byte
** aligned memory buffer from which the scratch allocations will be
** drawn, the size of each scratch allocation (sz),
** and the maximum number of scratch allocations (N).  The sz
** argument must be a multiple of 16.
** The first argument must be a pointer to an 8-byte aligned buffer
** of at least sz*N bytes of memory.
** ^SQLite will use no more than two scratch buffers per thread.  So
** N should be set to twice the expected maximum number of threads.
................................................................................
** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.
** The first pointer (the memory pointer) must be aligned to an 8-byte
** boundary or subsequent behavior of SQLite will be undefined.
** The minimum allocation size is capped at 2^12. Reasonable values
** for the minimum allocation size are 2^5 through 2^8.</dd>
**
** <dt>SQLITE_CONFIG_MUTEX</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** instance of the [sqlite3_mutex_methods] structure.  The argument specifies
** alternative low-level mutex routines to be used in place
** the mutex routines built into SQLite.)^  ^SQLite makes a copy of the
** content of the [sqlite3_mutex_methods] structure before the call to
................................................................................
** is invoked.
**
** <dl>
** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
** <dd> ^This option takes three additional arguments that determine the 
** [lookaside memory allocator] configuration for the [database connection].
** ^The first argument (the third parameter to [sqlite3_db_config()] is a
** pointer to a memory buffer to use for lookaside memory.
** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
** may be NULL in which case SQLite will allocate the
** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
** size of each lookaside buffer slot.  ^The third argument is the number of
** slots.  The size of the buffer in the first argument must be greater than
** or equal to the product of the second and third arguments.  The buffer
** must be aligned to an 8-byte boundary.  ^If the second argument to
................................................................................
** connection is not currently using lookaside memory, or in other words
** when the "current value" returned by
** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
** Any attempt to change the lookaside memory configuration when lookaside
** memory is in use leaves the configuration unchanged and returns 
** [SQLITE_BUSY].)^</dd>
**
** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
** <dd> ^This option is used to enable or disable the enforcement of
** [foreign key constraints].  There should be two additional arguments.
** The first argument is an integer which is 0 to disable FK enforcement,
** positive to enable FK enforcement or negative to leave FK enforcement
** unchanged.  The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether FK enforcement is off or on
** following this call.  The second parameter may be a NULL pointer, in
** which case the FK enforcement setting is not reported back. </dd>
**
** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
** There should be two additional arguments.
** The first argument is an integer which is 0 to disable triggers,
** positive to enable triggers or negative to leave the setting unchanged.
** The second parameter is a pointer to an integer into which
** is written 0 or 1 to indicate whether triggers are disabled or enabled
** following this call.  The second parameter may be a NULL pointer, in
** which case the trigger setting is not reported back. </dd>
**
** </dl>
*/
#define SQLITE_DBCONFIG_LOOKASIDE       1001  /* void* int int */
#define SQLITE_DBCONFIG_ENABLE_FKEY     1002  /* int int* */
#define SQLITE_DBCONFIG_ENABLE_TRIGGER  1003  /* int int* */


/*
** CAPI3REF: Enable Or Disable Extended Result Codes
**
** ^The sqlite3_extended_result_codes() routine enables or disables the
** [extended result codes] feature of SQLite. ^The extended result
................................................................................
** method.
*/
SQLITE_API void sqlite3_randomness(int N, void *P);

/*
** CAPI3REF: Compile-Time Authorization Callbacks
**
** ^This routine registers an authorizer callback with a particular
** [database connection], supplied in the first argument.
** ^The authorizer callback is invoked as SQL statements are being compiled
** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()].  ^At various
** points during the compilation process, as logic is being created
** to perform various actions, the authorizer callback is invoked to
** see if those actions are allowed.  ^The authorizer callback should
................................................................................
** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
*/
SQLITE_API const char *sqlite3_sql(sqlite3_stmt *pStmt);

/*
** CAPI3REF: Determine If An SQL Statement Writes The Database
**
** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
** and only if the [prepared statement] X makes no direct changes to
** the content of the database file.
**
** Note that [application-defined SQL functions] or
** [virtual tables] might change the database indirectly as a side effect.  
** ^(For example, if an application defines a function "eval()" that 
** calls [sqlite3_exec()], then the following SQL statement would
................................................................................
** An sqlite3_value object may be either "protected" or "unprotected".
** Some interfaces require a protected sqlite3_value.  Other interfaces
** will accept either a protected or an unprotected sqlite3_value.
** Every interface that accepts sqlite3_value arguments specifies
** whether or not it requires a protected sqlite3_value.
**
** The terms "protected" and "unprotected" refer to whether or not
** a mutex is held.  An internal mutex is held for a protected
** sqlite3_value object but no mutex is held for an unprotected
** sqlite3_value object.  If SQLite is compiled to be single-threaded
** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
** or if SQLite is run in one of reduced mutex modes 
** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
** then there is no distinction between protected and unprotected
** sqlite3_value objects and they can be used interchangeably.  However,
................................................................................
** interface returns a pointer to a zero-terminated UTF-8 string
** and sqlite3_column_name16() returns a pointer to a zero-terminated
** UTF-16 string.  ^The first parameter is the [prepared statement]
** that implements the [SELECT] statement. ^The second parameter is the
** column number.  ^The leftmost column is number 0.
**
** ^The returned string pointer is valid until either the [prepared statement]
** is destroyed by [sqlite3_finalize()] or until the statement is automatically
** reprepared by the first call to [sqlite3_step()] for a particular run
** or until the next call to
** sqlite3_column_name() or sqlite3_column_name16() on the same column.
**
** ^If sqlite3_malloc() fails during the processing of either routine
** (for example during a conversion from UTF-8 to UTF-16) then a
** NULL pointer is returned.
**
** ^The name of a result column is the value of the "AS" clause for
................................................................................
** table column that is the origin of a particular result column in
** [SELECT] statement.
** ^The name of the database or table or column can be returned as
** either a UTF-8 or UTF-16 string.  ^The _database_ routines return
** the database name, the _table_ routines return the table name, and
** the origin_ routines return the column name.
** ^The returned string is valid until the [prepared statement] is destroyed
** using [sqlite3_finalize()] or until the statement is automatically
** reprepared by the first call to [sqlite3_step()] for a particular run
** or until the same information is requested
** again in a different encoding.
**
** ^The names returned are the original un-aliased names of the
** database, table, and column.
**
** ^The first argument to these interfaces is a [prepared statement].
** ^These functions return information about the Nth result column returned by
................................................................................
** KEYWORDS: {application-defined SQL function}
** KEYWORDS: {application-defined SQL functions}
**
** ^These functions (collectively known as "function creation routines")
** are used to add SQL functions or aggregates or to redefine the behavior
** of existing SQL functions or aggregates.  The only differences between
** these routines are the text encoding expected for
** the second parameter (the name of the function being created)
** and the presence or absence of a destructor callback for
** the application data pointer.
**
** ^The first parameter is the [database connection] to which the SQL
** function is to be added.  ^If an application uses more than one database
** connection then application-defined SQL functions must be added
** to each database connection separately.
................................................................................
**
** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
** pointers to C-language functions that implement the SQL function or
** aggregate. ^A scalar SQL function requires an implementation of the xFunc
** callback only; NULL pointers must be passed as the xStep and xFinal
** parameters. ^An aggregate SQL function requires an implementation of xStep
** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
** SQL function or aggregate, pass NULL pointers for all three function
** callbacks.
**
** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
** then it is destructor for the application data pointer. 
** The destructor is invoked when the function is deleted, either by being
** overloaded or when the database connection closes.)^
** ^The destructor is also invoked if the call to
................................................................................
** ^The eTextRep argument determines the encoding of strings passed
** to the collating function callback, xCallback.
** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
** force strings to be UTF16 with native byte order.
** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
** on an even byte address.
**
** ^The fourth argument, pArg, is an application data pointer that is passed
** through as the first argument to the collating function callback.
**
** ^The fifth argument, xCallback, is a pointer to the collating function.
** ^Multiple collating functions can be registered using the same name but
** with different eTextRep parameters and SQLite will use whichever
** function requires the least amount of data transformation.
** ^If the xCallback argument is NULL then the collating function is
................................................................................
** that collation is no longer usable.
**
** ^The collating function callback is invoked with a copy of the pArg 
** application data pointer and with two strings in the encoding specified
** by the eTextRep argument.  The collating function must return an
** integer that is negative, zero, or positive
** if the first string is less than, equal to, or greater than the second,
** respectively.  A collating function must always return the same answer
** given the same inputs.  If two or more collating functions are registered
** to the same collation name (using different eTextRep values) then all
** must give an equivalent answer when invoked with equivalent strings.
** The collating function must obey the following properties for all
** strings A, B, and C:
**
** <ol>
................................................................................
** if one or more of following conditions are true:
**
** <ul>
** <li> The soft heap limit is set to zero.
** <li> Memory accounting is disabled using a combination of the
**      [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
**      the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
** <li> An alternative page cache implementation is specified using
**      [sqlite3_config]([SQLITE_CONFIG_PCACHE],...).
** <li> The page cache allocates from its own memory pool supplied
**      by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
**      from the heap.
** </ul>)^
**
** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
................................................................................
typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
typedef struct sqlite3_module sqlite3_module;

/*
** CAPI3REF: Virtual Table Object
** KEYWORDS: sqlite3_module {virtual table module}
**
** This structure, sometimes called a "virtual table module", 
** defines the implementation of a [virtual tables].  
** This structure consists mostly of methods for the module.
**
** ^A virtual table module is created by filling in a persistent
** instance of this structure and passing a pointer to that instance
** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
** ^The registration remains valid until it is replaced by a different
................................................................................
**
** ^(If the row that a BLOB handle points to is modified by an
** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
** then the BLOB handle is marked as "expired".
** This is true if any column of the row is changed, even a column
** other than the one the BLOB handle is open on.)^
** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
** ^(Changes written into a BLOB prior to the BLOB expiring are not
** rolled back by the expiration of the BLOB.  Such changes will eventually
** commit if the transaction continues to completion.)^
**
** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
** the opened blob.  ^The size of a blob may not be changed by this
** interface.  Use the [UPDATE] SQL command to change the size of a
................................................................................
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
** <dd>This parameter returns the number of lookaside memory slots currently
** checked out.</dd>)^
**
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
** <dd>This parameter returns the number malloc attempts that were 
** satisfied using lookaside memory. Only the high-water value is meaningful;
** the current value is always zero.)^

**
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
** <dd>This parameter returns the number malloc attempts that might have
** been satisfied using lookaside memory but failed due to the amount of
** memory requested being larger than the lookaside slot size.
** Only the high-water value is meaningful;
** the current value is always zero.)^

**
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
** <dd>This parameter returns the number malloc attempts that might have
** been satisfied using lookaside memory but failed due to all lookaside
** memory already being in use.
** Only the high-water value is meaningful;
** the current value is always zero.)^

**
** ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
** <dd>This parameter returns the approximate number of of bytes of heap
** memory used by all pager caches associated with the database connection.)^
** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
**
** ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
................................................................................
** connection D.  ^If the database connection D is not in
** [WAL | write-ahead log mode] then this interface is a harmless no-op.
**
** ^The [wal_checkpoint pragma] can be used to invoke this interface
** from SQL.  ^The [sqlite3_wal_autocheckpoint()] interface and the
** [wal_autocheckpoint pragma] can be used to cause this interface to be
** run whenever the WAL reaches a certain size threshold.
**
** See also: [sqlite3_wal_checkpoint_v2()]
*/
SQLITE_API int sqlite3_wal_checkpoint(sqlite3 *db, const char *zDb);

/*
** CAPI3REF: Checkpoint a database
**
** Run a checkpoint operation on WAL database zDb attached to database 
** handle db. The specific operation is determined by the value of the 
** eMode parameter:
**
** <dl>
** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>
**   Checkpoint as many frames as possible without waiting for any database 
**   readers or writers to finish. Sync the db file if all frames in the log
**   are checkpointed. This mode is the same as calling 
**   sqlite3_wal_checkpoint(). The busy-handler callback is never invoked.
**
** <dt>SQLITE_CHECKPOINT_FULL<dd>
**   This mode blocks (calls the busy-handler callback) until there is no
**   database writer and all readers are reading from the most recent database
**   snapshot. It then checkpoints all frames in the log file and syncs the
**   database file. This call blocks database writers while it is running,
**   but not database readers.
**
** <dt>SQLITE_CHECKPOINT_RESTART<dd>
**   This mode works the same way as SQLITE_CHECKPOINT_FULL, except after 
**   checkpointing the log file it blocks (calls the busy-handler callback)
**   until all readers are reading from the database file only. This ensures 
**   that the next client to write to the database file restarts the log file 
**   from the beginning. This call blocks database writers while it is running,
**   but not database readers.
** </dl>
**
** If pnLog is not NULL, then *pnLog is set to the total number of frames in
** the log file before returning. If pnCkpt is not NULL, then *pnCkpt is set to
** the total number of checkpointed frames (including any that were already
** checkpointed when this function is called). *pnLog and *pnCkpt may be
** populated even if sqlite3_wal_checkpoint_v2() returns other than SQLITE_OK.
** If no values are available because of an error, they are both set to -1
** before returning to communicate this to the caller.
**
** All calls obtain an exclusive "checkpoint" lock on the database file. If
** any other process is running a checkpoint operation at the same time, the 
** lock cannot be obtained and SQLITE_BUSY is returned. Even if there is a 
** busy-handler configured, it will not be invoked in this case.
**
** The SQLITE_CHECKPOINT_FULL and RESTART modes also obtain the exclusive 
** "writer" lock on the database file. If the writer lock cannot be obtained
** immediately, and a busy-handler is configured, it is invoked and the writer
** lock retried until either the busy-handler returns 0 or the lock is
** successfully obtained. The busy-handler is also invoked while waiting for
** database readers as described above. If the busy-handler returns 0 before
** the writer lock is obtained or while waiting for database readers, the
** checkpoint operation proceeds from that point in the same way as 
** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible 
** without blocking any further. SQLITE_BUSY is returned in this case.
**
** If parameter zDb is NULL or points to a zero length string, then the
** specified operation is attempted on all WAL databases. In this case the
** values written to output parameters *pnLog and *pnCkpt are undefined. If 
** an SQLITE_BUSY error is encountered when processing one or more of the 
** attached WAL databases, the operation is still attempted on any remaining 
** attached databases and SQLITE_BUSY is returned to the caller. If any other 
** error occurs while processing an attached database, processing is abandoned 
** and the error code returned to the caller immediately. If no error 
** (SQLITE_BUSY or otherwise) is encountered while processing the attached 
** databases, SQLITE_OK is returned.
**
** If database zDb is the name of an attached database that is not in WAL
** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. If
** zDb is not NULL (or a zero length string) and is not the name of any
** attached database, SQLITE_ERROR is returned to the caller.
*/
SQLITE_API int sqlite3_wal_checkpoint_v2(
  sqlite3 *db,                    /* Database handle */
  const char *zDb,                /* Name of attached database (or NULL) */
  int eMode,                      /* SQLITE_CHECKPOINT_* value */
  int *pnLog,                     /* OUT: Size of WAL log in frames */
  int *pnCkpt                     /* OUT: Total number of frames checkpointed */
);

/*
** CAPI3REF: Checkpoint operation parameters
**
** These constants can be used as the 3rd parameter to
** [sqlite3_wal_checkpoint_v2()].  See the [sqlite3_wal_checkpoint_v2()]
** documentation for additional information about the meaning and use of
** each of these values.
*/
#define SQLITE_CHECKPOINT_PASSIVE 0
#define SQLITE_CHECKPOINT_FULL    1
#define SQLITE_CHECKPOINT_RESTART 2


/*
** Undo the hack that converts floating point types to integer for
** builds on processors without floating point support.
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# undef double
................................................................................

/*
** Forward declarations of structure
*/
typedef struct Btree Btree;
typedef struct BtCursor BtCursor;
typedef struct BtShared BtShared;














SQLITE_PRIVATE int sqlite3BtreeOpen(
  const char *zFilename,   /* Name of database file to open */
  sqlite3 *db,             /* Associated database connection */
  Btree **ppBtree,         /* Return open Btree* here */
  int flags,               /* Flags */
................................................................................
SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*, int);
SQLITE_PRIVATE int sqlite3BtreeCommit(Btree*);
SQLITE_PRIVATE int sqlite3BtreeRollback(Btree*);
SQLITE_PRIVATE int sqlite3BtreeBeginStmt(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCreateTable(Btree*, int*, int flags);
SQLITE_PRIVATE int sqlite3BtreeIsInTrans(Btree*);
SQLITE_PRIVATE int sqlite3BtreeIsInReadTrans(Btree*);
SQLITE_PRIVATE int sqlite3BtreeIsInBackup(Btree*);
................................................................................

#ifdef SQLITE_TEST
SQLITE_PRIVATE int sqlite3BtreeCursorInfo(BtCursor*, int*, int);
SQLITE_PRIVATE void sqlite3BtreeCursorList(Btree*);
#endif

#ifndef SQLITE_OMIT_WAL
SQLITE_PRIVATE   int sqlite3BtreeCheckpoint(Btree*, int, int *, int *);
#endif

/*
** If we are not using shared cache, then there is no need to
** use mutexes to access the BtShared structures.  So make the
** Enter and Leave procedures no-ops.
*/
................................................................................
SQLITE_PRIVATE   void sqlite3BtreeEnterAll(sqlite3*);
#else
# define sqlite3BtreeEnter(X) 
# define sqlite3BtreeEnterAll(X)
#endif

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE
SQLITE_PRIVATE   int sqlite3BtreeSharable(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeLeave(Btree*);
SQLITE_PRIVATE   void sqlite3BtreeEnterCursor(BtCursor*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveCursor(BtCursor*);
SQLITE_PRIVATE   void sqlite3BtreeLeaveAll(sqlite3*);



#ifndef NDEBUG
  /* These routines are used inside assert() statements only. */
SQLITE_PRIVATE   int sqlite3BtreeHoldsMutex(Btree*);
SQLITE_PRIVATE   int sqlite3BtreeHoldsAllMutexes(sqlite3*);
SQLITE_PRIVATE   int sqlite3SchemaMutexHeld(sqlite3*,int,Schema*);
#endif
#else

# define sqlite3BtreeSharable(X) 0
# define sqlite3BtreeLeave(X)
# define sqlite3BtreeEnterCursor(X)
# define sqlite3BtreeLeaveCursor(X)
# define sqlite3BtreeLeaveAll(X)




# define sqlite3BtreeHoldsMutex(X) 1
# define sqlite3BtreeHoldsAllMutexes(X) 1
# define sqlite3SchemaMutexHeld(X,Y,Z) 1
#endif


#endif /* _BTREE_H_ */

/************** End of btree.h ***********************************************/
/************** Continuing where we left off in sqliteInt.h ******************/
................................................................................
#define P4_DYNAMIC  (-1)  /* Pointer to a string obtained from sqliteMalloc() */
#define P4_STATIC   (-2)  /* Pointer to a static string */
#define P4_COLLSEQ  (-4)  /* P4 is a pointer to a CollSeq structure */
#define P4_FUNCDEF  (-5)  /* P4 is a pointer to a FuncDef structure */
#define P4_KEYINFO  (-6)  /* P4 is a pointer to a KeyInfo structure */
#define P4_VDBEFUNC (-7)  /* P4 is a pointer to a VdbeFunc structure */
#define P4_MEM      (-8)  /* P4 is a pointer to a Mem*    structure */
#define P4_TRANSIENT  0   /* P4 is a pointer to a transient string */
#define P4_VTAB     (-10) /* P4 is a pointer to an sqlite3_vtab structure */
#define P4_MPRINTF  (-11) /* P4 is a string obtained from sqlite3_mprintf() */
#define P4_REAL     (-12) /* P4 is a 64-bit floating point value */
#define P4_INT64    (-13) /* P4 is a 64-bit signed integer */
#define P4_INT32    (-14) /* P4 is a 32-bit signed integer */
#define P4_INTARRAY (-15) /* P4 is a vector of 32-bit integers */
#define P4_SUBPROGRAM  (-18) /* P4 is a pointer to a SubProgram structure */
................................................................................
SQLITE_PRIVATE int sqlite3PagerSync(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerCommitPhaseTwo(Pager*);
SQLITE_PRIVATE int sqlite3PagerRollback(Pager*);
SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager);

SQLITE_PRIVATE int sqlite3PagerCheckpoint(Pager *pPager, int, int*, int*);
SQLITE_PRIVATE int sqlite3PagerWalSupported(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager);
SQLITE_PRIVATE int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
SQLITE_PRIVATE int sqlite3PagerCloseWal(Pager *pPager);

/* Functions used to query pager state and configuration. */
SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager*);
................................................................................
  u8 inTrans;          /* 0: not writable.  1: Transaction.  2: Checkpoint */
  u8 safety_level;     /* How aggressive at syncing data to disk */
  Schema *pSchema;     /* Pointer to database schema (possibly shared) */
};

/*
** An instance of the following structure stores a database schema.
**
** Most Schema objects are associated with a Btree.  The exception is
** the Schema for the TEMP databaes (sqlite3.aDb[1]) which is free-standing.
** In shared cache mode, a single Schema object can be shared by multiple
** Btrees that refer to the same underlying BtShared object.
** 
** Schema objects are automatically deallocated when the last Btree that
** references them is destroyed.   The TEMP Schema is manually freed by
** sqlite3_close().
*
** A thread must be holding a mutex on the corresponding Btree in order
** to access Schema content.  This implies that the thread must also be
** holding a mutex on the sqlite3 connection pointer that owns the Btree.
** For a TEMP Schema, on the connection mutex is required.
*/
struct Schema {
  int schema_cookie;   /* Database schema version number for this file */
  int iGeneration;     /* Generation counter.  Incremented with each change */
  Hash tblHash;        /* All tables indexed by name */
  Hash idxHash;        /* All (named) indices indexed by name */
  Hash trigHash;       /* All triggers indexed by name */
  Hash fkeyHash;       /* All foreign keys by referenced table name */
  Table *pSeqTab;      /* The sqlite_sequence table used by AUTOINCREMENT */
  u8 file_format;      /* Schema format version for this file */
  u8 enc;              /* Text encoding used by this database */
................................................................................
#define SQLITE_RecoveryMode   0x00800000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x01000000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x02000000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x04000000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x08000000  /* Enable automatic indexes */
#define SQLITE_PreferBuiltin  0x10000000  /* Preference to built-in funcs */
#define SQLITE_LoadExtension  0x20000000  /* Enable load_extension */
#define SQLITE_EnableTrigger  0x40000000  /* True to enable triggers */

/*
** Bits of the sqlite3.flags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface.
** These must be the low-order bits of the flags field.
*/
#define SQLITE_QueryFlattener 0x01        /* Disable query flattening */
................................................................................
** schema. This is because each database connection requires its own unique
** instance of the sqlite3_vtab* handle used to access the virtual table 
** implementation. sqlite3_vtab* handles can not be shared between 
** database connections, even when the rest of the in-memory database 
** schema is shared, as the implementation often stores the database
** connection handle passed to it via the xConnect() or xCreate() method
** during initialization internally. This database connection handle may
** then be used by the virtual table implementation to access real tables 
** within the database. So that they appear as part of the callers 
** transaction, these accesses need to be made via the same database 
** connection as that used to execute SQL operations on the virtual table.
**
** All VTable objects that correspond to a single table in a shared
** database schema are initially stored in a linked-list pointed to by
** the Table.pVTable member variable of the corresponding Table object.
................................................................................
  int nColumn;     /* Number of columns in the table used by this index */
  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
  Table *pTable;   /* The SQL table being indexed */
  int tnum;        /* Page containing root of this index in database file */
  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
  u8 bUnordered;   /* Use this index for == or IN queries only */
  char *zColAff;   /* String defining the affinity of each column */
  Index *pNext;    /* The next index associated with the same table */
  Schema *pSchema; /* Schema containing this index */
  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
  char **azColl;   /* Array of collation sequence names for index */
  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */
};
................................................................................
*/
struct Expr {
  u8 op;                 /* Operation performed by this node */
  char affinity;         /* The affinity of the column or 0 if not a column */
  u16 flags;             /* Various flags.  EP_* See below */
  union {
    char *zToken;          /* Token value. Zero terminated and dequoted */
    int iValue;            /* Non-negative integer value if EP_IntValue */
  } u;

  /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction. 
  *********************************************************************/

................................................................................
  Trigger *pTrigger;      /* Trigger this program was coded from */
  int orconf;             /* Default ON CONFLICT policy */
  SubProgram *pProgram;   /* Program implementing pTrigger/orconf */
  u32 aColmask[2];        /* Masks of old.*, new.* columns accessed */
  TriggerPrg *pNext;      /* Next entry in Parse.pTriggerPrg list */
};

/*
** The yDbMask datatype for the bitmask of all attached databases.
*/
#if SQLITE_MAX_ATTACHED>30
  typedef sqlite3_uint64 yDbMask;
#else
  typedef unsigned int yDbMask;
#endif

/*
** An SQL parser context.  A copy of this structure is passed through
** the parser and down into all the parser action routine in order to
** carry around information that is global to the entire parse.
**
** The structure is divided into two parts.  When the parser and code
** generate call themselves recursively, the first part of the structure
................................................................................
    int iTable;           /* Table cursor number */
    int iColumn;          /* Table column number */
    u8 tempReg;           /* iReg is a temp register that needs to be freed */
    int iLevel;           /* Nesting level */
    int iReg;             /* Reg with value of this column. 0 means none. */
    int lru;              /* Least recently used entry has the smallest value */
  } aColCache[SQLITE_N_COLCACHE];  /* One for each column cache entry */
  yDbMask writeMask;   /* Start a write transaction on these databases */
  yDbMask cookieMask;  /* Bitmask of schema verified databases */
  u8 isMultiWrite;     /* True if statement may affect/insert multiple rows */
  u8 mayAbort;         /* True if statement may throw an ABORT exception */
  int cookieGoto;      /* Address of OP_Goto to cookie verifier subroutine */
  int cookieValue[SQLITE_MAX_ATTACHED+2];  /* Values of cookies to verify */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
................................................................................
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);
SQLITE_PRIVATE void sqlite3PrngSaveState(void);
SQLITE_PRIVATE void sqlite3PrngRestoreState(void);
SQLITE_PRIVATE void sqlite3PrngResetState(void);
SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*);
SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);
SQLITE_PRIVATE void sqlite3CodeVerifyNamedSchema(Parse*, const char *zDb);
SQLITE_PRIVATE void sqlite3BeginTransaction(Parse*, int);
SQLITE_PRIVATE void sqlite3CommitTransaction(Parse*);
SQLITE_PRIVATE void sqlite3RollbackTransaction(Parse*);
SQLITE_PRIVATE void sqlite3Savepoint(Parse*, int, Token*);
SQLITE_PRIVATE void sqlite3CloseSavepoints(sqlite3 *);
SQLITE_PRIVATE int sqlite3ExprIsConstant(Expr*);
SQLITE_PRIVATE int sqlite3ExprIsConstantNotJoin(Expr*);
................................................................................
SQLITE_PRIVATE CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
SQLITE_PRIVATE CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
SQLITE_PRIVATE Expr *sqlite3ExprSetColl(Expr*, CollSeq*);
SQLITE_PRIVATE Expr *sqlite3ExprSetCollByToken(Parse *pParse, Expr*, Token*);
SQLITE_PRIVATE int sqlite3CheckCollSeq(Parse *, CollSeq *);
SQLITE_PRIVATE int sqlite3CheckObjectName(Parse *, const char *);
SQLITE_PRIVATE void sqlite3VdbeSetChanges(sqlite3 *, int);
SQLITE_PRIVATE int sqlite3AddInt64(i64*,i64);
SQLITE_PRIVATE int sqlite3SubInt64(i64*,i64);
SQLITE_PRIVATE int sqlite3MulInt64(i64*,i64);
SQLITE_PRIVATE int sqlite3AbsInt32(int);

SQLITE_PRIVATE const void *sqlite3ValueText(sqlite3_value*, u8);
SQLITE_PRIVATE int sqlite3ValueBytes(sqlite3_value*, u8);
SQLITE_PRIVATE void sqlite3ValueSetStr(sqlite3_value*, int, const void *,u8, 
                        void(*)(void*));
SQLITE_PRIVATE void sqlite3ValueFree(sqlite3_value*);
SQLITE_PRIVATE sqlite3_value *sqlite3ValueNew(sqlite3 *);
................................................................................
SQLITE_PRIVATE const Token sqlite3IntTokens[];
SQLITE_PRIVATE SQLITE_WSD struct Sqlite3Config sqlite3Config;
SQLITE_PRIVATE SQLITE_WSD FuncDefHash sqlite3GlobalFunctions;
#ifndef SQLITE_OMIT_WSD
SQLITE_PRIVATE int sqlite3PendingByte;
#endif
#endif
SQLITE_PRIVATE void sqlite3RootPageMoved(sqlite3*, int, int, int);
SQLITE_PRIVATE void sqlite3Reindex(Parse*, Token*, Token*);
SQLITE_PRIVATE void sqlite3AlterFunctions(void);
SQLITE_PRIVATE void sqlite3AlterRenameTable(Parse*, SrcList*, Token*);
SQLITE_PRIVATE int sqlite3GetToken(const unsigned char *, int *);
SQLITE_PRIVATE void sqlite3NestedParse(Parse*, const char*, ...);
SQLITE_PRIVATE void sqlite3ExpirePreparedStatements(sqlite3*);
SQLITE_PRIVATE int sqlite3CodeSubselect(Parse *, Expr *, int, int);
................................................................................
SQLITE_PRIVATE int sqlite3FindDbName(sqlite3 *, const char *);
SQLITE_PRIVATE int sqlite3AnalysisLoad(sqlite3*,int iDB);
SQLITE_PRIVATE void sqlite3DeleteIndexSamples(sqlite3*,Index*);
SQLITE_PRIVATE void sqlite3DefaultRowEst(Index*);
SQLITE_PRIVATE void sqlite3RegisterLikeFunctions(sqlite3*, int);
SQLITE_PRIVATE int sqlite3IsLikeFunction(sqlite3*,Expr*,int*,char*);
SQLITE_PRIVATE void sqlite3MinimumFileFormat(Parse*, int, int);
SQLITE_PRIVATE void sqlite3SchemaClear(void *);
SQLITE_PRIVATE Schema *sqlite3SchemaGet(sqlite3 *, Btree *);
SQLITE_PRIVATE int sqlite3SchemaToIndex(sqlite3 *db, Schema *);
SQLITE_PRIVATE KeyInfo *sqlite3IndexKeyinfo(Parse *, Index *);
SQLITE_PRIVATE int sqlite3CreateFunc(sqlite3 *, const char *, int, int, void *, 
  void (*)(sqlite3_context*,int,sqlite3_value **),
  void (*)(sqlite3_context*,int,sqlite3_value **), void (*)(sqlite3_context*),
  FuncDestructor *pDestructor
................................................................................
SQLITE_PRIVATE int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
SQLITE_PRIVATE int sqlite3Reprepare(Vdbe*);
SQLITE_PRIVATE void sqlite3ExprListCheckLength(Parse*, ExprList*, const char*);
SQLITE_PRIVATE CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
SQLITE_PRIVATE int sqlite3TempInMemory(const sqlite3*);
SQLITE_PRIVATE VTable *sqlite3GetVTable(sqlite3*, Table*);
SQLITE_PRIVATE const char *sqlite3JournalModename(int);
SQLITE_PRIVATE int sqlite3Checkpoint(sqlite3*, int, int, int*, int*);
SQLITE_PRIVATE int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);

/* Declarations for functions in fkey.c. All of these are replaced by
** no-op macros if OMIT_FOREIGN_KEY is defined. In this case no foreign
** key functionality is available. If OMIT_TRIGGER is defined but
** OMIT_FOREIGN_KEY is not, only some of the functions are no-oped. In
** this case foreign keys are parsed, but no other functionality is 
................................................................................
  u8 runOnlyOnce;         /* Automatically expire on reset */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
  yDbMask lockMask;       /* Subset of btreeMask that requires a lock */
  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
  int aCounter[3];        /* Counters used by sqlite3_stmt_status() */

#ifndef SQLITE_OMIT_TRACE
  i64 startTime;          /* Time when query started - used for profiling */
#endif
  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
  char *zSql;             /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */
................................................................................
SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
SQLITE_PRIVATE const char *sqlite3OpcodeName(int);
SQLITE_PRIVATE int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
SQLITE_PRIVATE int sqlite3VdbeCloseStatement(Vdbe *, int);
SQLITE_PRIVATE void sqlite3VdbeFrameDelete(VdbeFrame*);
SQLITE_PRIVATE int sqlite3VdbeFrameRestore(VdbeFrame *);
SQLITE_PRIVATE void sqlite3VdbeMemStoreType(Mem *pMem);

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
SQLITE_PRIVATE   void sqlite3VdbeEnter(Vdbe*);
SQLITE_PRIVATE   void sqlite3VdbeLeave(Vdbe*);
#else
# define sqlite3VdbeEnter(X)
# define sqlite3VdbeLeave(X)
#endif

#ifdef SQLITE_DEBUG
SQLITE_PRIVATE void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*);
#endif

#ifndef SQLITE_OMIT_FOREIGN_KEY
SQLITE_PRIVATE int sqlite3VdbeCheckFk(Vdbe *, int);
#else
# define sqlite3VdbeCheckFk(p,i) 0
#endif







SQLITE_PRIVATE int sqlite3VdbeMemTranslate(Mem*, u8);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   void sqlite3VdbePrintSql(Vdbe*);
SQLITE_PRIVATE   void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);
#endif
SQLITE_PRIVATE int sqlite3VdbeMemHandleBom(Mem *pMem);

................................................................................
    ** to store the schema for all databases (main, temp, and any ATTACHed
    ** databases.  *pHighwater is set to zero.
    */
    case SQLITE_DBSTATUS_SCHEMA_USED: {
      int i;                      /* Used to iterate through schemas */
      int nByte = 0;              /* Used to accumulate return value */

      sqlite3BtreeEnterAll(db);
      db->pnBytesFreed = &nByte;
      for(i=0; i<db->nDb; i++){
        Schema *pSchema = db->aDb[i].pSchema;
        if( ALWAYS(pSchema!=0) ){
          HashElem *p;

          nByte += sqlite3GlobalConfig.m.xRoundup(sizeof(HashElem)) * (
................................................................................
          }
          for(p=sqliteHashFirst(&pSchema->tblHash); p; p=sqliteHashNext(p)){
            sqlite3DeleteTable(db, (Table *)sqliteHashData(p));
          }
        }
      }
      db->pnBytesFreed = 0;
      sqlite3BtreeLeaveAll(db);

      *pHighwater = 0;
      *pCurrent = nByte;
      break;
    }

    /*
................................................................................

  /*
  ** Space for tracking which blocks are checked out and the size
  ** of each block.  One byte per block.
  */
  u8 *aCtrl;

} mem5;

/*
** Access the static variable through a macro for SQLITE_OMIT_WSD
*/
#define mem5 GLOBAL(struct Mem5Global, mem5)

/*
................................................................................
**             memsys5Log(4) -> 2
**             memsys5Log(5) -> 3
**             memsys5Log(8) -> 3
**             memsys5Log(9) -> 4
*/
static int memsys5Log(int iValue){
  int iLog;
  for(iLog=0; (iLog<(int)((sizeof(int)*8)-1)) && (1<<iLog)<iValue; iLog++);
  return iLog;
}

/*
** Initialize the memory allocator.
**
** This routine is not threadsafe.  The caller must be holding a mutex
................................................................................
  */
  assert( (sizeof(Mem5Link)&(sizeof(Mem5Link)-1))==0 );

  nByte = sqlite3GlobalConfig.nHeap;
  zByte = (u8*)sqlite3GlobalConfig.pHeap;
  assert( zByte!=0 );  /* sqlite3_config() does not allow otherwise */

  /* boundaries on sqlite3GlobalConfig.mnReq are enforced in sqlite3_config() */
  nMinLog = memsys5Log(sqlite3GlobalConfig.mnReq);
  mem5.szAtom = (1<<nMinLog);
  while( (int)sizeof(Mem5Link)>mem5.szAtom ){
    mem5.szAtom = mem5.szAtom << 1;
  }

  mem5.nBlock = (nByte / (mem5.szAtom+sizeof(u8)));
................................................................................
/*
** The mutex object
** Each recursive mutex is an instance of the following structure.
*/
struct sqlite3_mutex {
  HMTX mutex;       /* Mutex controlling the lock */
  int  id;          /* Mutex type */
#ifdef SQLITE_DEBUG
 int   trace;       /* True to trace changes */
#endif
};

#ifdef SQLITE_DEBUG
#define SQLITE3_MUTEX_INITIALIZER { 0, 0, 0 }
#else
#define SQLITE3_MUTEX_INITIALIZER { 0, 0 }
#endif

/*
** Initialize and deinitialize the mutex subsystem.
*/
static int os2MutexInit(void){ return SQLITE_OK; }
static int os2MutexEnd(void){ return SQLITE_OK; }

................................................................................
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated. 
** SQLite will unwind its stack and return an error.  The argument
** to sqlite3_mutex_alloc() is one of these integer constants:
**
** <ul>
** <li>  SQLITE_MUTEX_FAST
** <li>  SQLITE_MUTEX_RECURSIVE
** <li>  SQLITE_MUTEX_STATIC_MASTER
** <li>  SQLITE_MUTEX_STATIC_MEM
** <li>  SQLITE_MUTEX_STATIC_MEM2
** <li>  SQLITE_MUTEX_STATIC_PRNG
** <li>  SQLITE_MUTEX_STATIC_LRU
** <li>  SQLITE_MUTEX_STATIC_LRU2
** </ul>
**
** The first two constants cause sqlite3_mutex_alloc() to create
** a new mutex.  The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
** The mutex implementation does not need to make a distinction
** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
** not want to.  But SQLite will only request a recursive mutex in
** cases where it really needs one.  If a faster non-recursive mutex
** implementation is available on the host platform, the mutex subsystem
** might return such a mutex in response to SQLITE_MUTEX_FAST.
**
** The other allowed parameters to sqlite3_mutex_alloc() each return
** a pointer to a static preexisting mutex.  Six static mutexes are
** used by the current version of SQLite.  Future versions of SQLite
** may add additional static mutexes.  Static mutexes are for internal
** use by SQLite only.  Applications that use SQLite mutexes should
** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
** SQLITE_MUTEX_RECURSIVE.
**
** Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
................................................................................
          p = NULL;
        }
      }
      break;
    }
    default: {
      static volatile int isInit = 0;
      static sqlite3_mutex staticMutexes[6] = {
        SQLITE3_MUTEX_INITIALIZER,
        SQLITE3_MUTEX_INITIALIZER,
        SQLITE3_MUTEX_INITIALIZER,
        SQLITE3_MUTEX_INITIALIZER,
        SQLITE3_MUTEX_INITIALIZER,
        SQLITE3_MUTEX_INITIALIZER,
      };
      if ( !isInit ){
        APIRET rc;
        PTIB ptib;
        PPIB ppib;
        HMTX mutex;
        char name[32];
................................................................................


/*
** This routine deallocates a previously allocated mutex.
** SQLite is careful to deallocate every mutex that it allocates.
*/
static void os2MutexFree(sqlite3_mutex *p){
#ifdef SQLITE_DEBUG
  TID tid;
  PID pid;
  ULONG ulCount;
  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
  assert( ulCount==0 );
  assert( p->id==SQLITE_MUTEX_FAST || p->id==SQLITE_MUTEX_RECURSIVE );
#endif
  DosCloseMutexSem( p->mutex );
  sqlite3_free( p );
}

#ifdef SQLITE_DEBUG
/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
................................................................................
** intended for use inside assert() statements.
*/
static int os2MutexHeld(sqlite3_mutex *p){
  TID tid;
  PID pid;
  ULONG ulCount;
  PTIB ptib;

  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
  if( ulCount==0 || ( ulCount>1 && p->id!=SQLITE_MUTEX_RECURSIVE ) )
    return 0;
  DosGetInfoBlocks(&ptib, NULL);
  return tid==ptib->tib_ptib2->tib2_ultid;


}
static int os2MutexNotheld(sqlite3_mutex *p){
  TID tid;
  PID pid;
  ULONG ulCount;
  PTIB ptib;

  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
  if( ulCount==0 )
    return 1;
  DosGetInfoBlocks(&ptib, NULL);
  return tid!=ptib->tib_ptib2->tib2_ultid;
}
static void os2MutexTrace(sqlite3_mutex *p, char *pAction){
  TID   tid;
  PID   pid;
  ULONG ulCount;
  DosQueryMutexSem(p->mutex, &pid, &tid, &ulCount);
  printf("%s mutex %p (%d) with nRef=%ld\n", pAction, (void*)p, p->trace, ulCount);
}
#endif

/*
** The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
** to enter a mutex.  If another thread is already within the mutex,
** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
................................................................................
** upon successful entry.  Mutexes created using SQLITE_MUTEX_RECURSIVE can
** be entered multiple times by the same thread.  In such cases the,
** mutex must be exited an equal number of times before another thread
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
static void os2MutexEnter(sqlite3_mutex *p){




  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
  DosRequestMutexSem(p->mutex, SEM_INDEFINITE_WAIT);



#ifdef SQLITE_DEBUG
  if( p->trace ) os2MutexTrace(p, "enter");
#endif
}
static int os2MutexTry(sqlite3_mutex *p){
  int rc = SQLITE_BUSY;




  assert( p->id==SQLITE_MUTEX_RECURSIVE || os2MutexNotheld(p) );
  if( DosRequestMutexSem(p->mutex, SEM_IMMEDIATE_RETURN) == NO_ERROR ) {



    rc = SQLITE_OK;

#ifdef SQLITE_DEBUG
    if( p->trace ) os2MutexTrace(p, "try");
#endif
  }

  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
static void os2MutexLeave(sqlite3_mutex *p){
  assert( os2MutexHeld(p) );








  DosReleaseMutexSem(p->mutex);
#ifdef SQLITE_DEBUG
  if( p->trace ) os2MutexTrace(p, "leave");
#endif
}

SQLITE_PRIVATE sqlite3_mutex_methods const *sqlite3DefaultMutex(void){
  static const sqlite3_mutex_methods sMutex = {
    os2MutexInit,
    os2MutexEnd,
    os2MutexAlloc,
................................................................................
    os2MutexFree,
    os2MutexEnter,
    os2MutexTry,
    os2MutexLeave,
#ifdef SQLITE_DEBUG
    os2MutexHeld,
    os2MutexNotheld
#else
    0,
    0
#endif
  };

  return &sMutex;
}
#endif /* SQLITE_MUTEX_OS2 */

................................................................................
    rc = SQLITE_OK;
  }
#else
  UNUSED_PARAMETER(p);
#endif
#ifdef SQLITE_DEBUG
  if( rc==SQLITE_OK && p->trace ){
    printf("try mutex %p (%d) with nRef=%d\n", p, p->trace, p->nRef);
  }
#endif
  return rc;
}

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
................................................................................
      /* Release memory from the SQLITE_CONFIG_SCRATCH allocation */
      ScratchFreeslot *pSlot;
      pSlot = (ScratchFreeslot*)p;
      sqlite3_mutex_enter(mem0.mutex);
      pSlot->pNext = mem0.pScratchFree;
      mem0.pScratchFree = pSlot;
      mem0.nScratchFree++;
      assert( mem0.nScratchFree <= (u32)sqlite3GlobalConfig.nScratch );
      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, -1);
      sqlite3_mutex_leave(mem0.mutex);
    }else{
      /* Release memory back to the heap */
      assert( sqlite3MemdebugHasType(p, MEMTYPE_SCRATCH) );
      assert( sqlite3MemdebugNoType(p, ~MEMTYPE_SCRATCH) );
      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
................................................................................
            v = va_arg(ap,i64);
          }else if( flag_long ){
            v = va_arg(ap,long int);
          }else{
            v = va_arg(ap,int);
          }
          if( v<0 ){
            if( v==SMALLEST_INT64 ){
              longvalue = ((u64)1)<<63;
            }else{
              longvalue = -v;
            }
            prefix = '-';
          }else{
            longvalue = v;
            if( flag_plussign )        prefix = '+';
            else if( flag_blanksign )  prefix = ' ';
            else                       prefix = 0;
          }
................................................................................
        || (c&0xFFFFF800)==0xD800                          \
        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
  }
SQLITE_PRIVATE int sqlite3Utf8Read(
  const unsigned char *zIn,       /* First byte of UTF-8 character */
  const unsigned char **pzNext    /* Write first byte past UTF-8 char here */
){
  unsigned int c;

  /* Same as READ_UTF8() above but without the zTerm parameter.
  ** For this routine, we assume the UTF8 string is always zero-terminated.
  */
  c = *(zIn++);
  if( c>=0xc0 ){
    c = sqlite3Utf8Trans1[c-0xc0];
................................................................................
#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
/*
** Translate UTF-8 to UTF-8.
**
** This has the effect of making sure that the string is well-formed
** UTF-8.  Miscoded characters are removed.
**
** The translation is done in-place and aborted if the output
** overruns the input.
*/
SQLITE_PRIVATE int sqlite3Utf8To8(unsigned char *zIn){
  unsigned char *zOut = zIn;
  unsigned char *zStart = zIn;
  u32 c;

  while( zIn[0] && zOut<=zIn ){
    c = sqlite3Utf8Read(zIn, (const u8**)&zIn);
    if( c!=0xfffd ){
      WRITE_UTF8(zOut, c);
    }
  }
  *zOut = 0;
  return (int)(zOut - zStart);
................................................................................
#endif

/*
** Routine needed to support the testcase() macro.
*/
#ifdef SQLITE_COVERAGE_TEST
SQLITE_PRIVATE void sqlite3Coverage(int x){
  static unsigned dummy = 0;
  dummy += (unsigned)x;
}
#endif

#ifndef SQLITE_OMIT_FLOATING_POINT
/*
** Return true if the floating point value is Not a Number (NaN).
**
................................................................................
    testcase( c==(+1) );
  }
  return c;
}


/*
** Convert zNum to a 64-bit signed integer.
**
** If the zNum value is representable as a 64-bit twos-complement 
** integer, then write that value into *pNum and return 0.
**
** If zNum is exactly 9223372036854665808, return 2.  This special
** case is broken out because while 9223372036854665808 cannot be a 
** signed 64-bit integer, its negative -9223372036854665808 can be.
**
** If zNum is too big for a 64-bit integer and is not
** 9223372036854665808 then return 1.
**
** length is the number of bytes in the string (bytes, not characters).
** The string is not necessarily zero-terminated.  The encoding is
** given by enc.
*/
SQLITE_PRIVATE int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
  int incr = (enc==SQLITE_UTF8?1:2);
  u64 u = 0;
  int neg = 0; /* assume positive */
  int i;
  int c = 0;
  const char *zStart;
  const char *zEnd = zNum + length;
  if( enc==SQLITE_UTF16BE ) zNum++;
  while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
  if( zNum<zEnd ){
    if( *zNum=='-' ){
      neg = 1;
      zNum+=incr;
    }else if( *zNum=='+' ){
      zNum+=incr;
    }

  }
  zStart = zNum;
  while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
  for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
    u = u*10 + c - '0';
  }
  if( u>LARGEST_INT64 ){
    *pNum = SMALLEST_INT64;
  }else if( neg ){
    *pNum = -(i64)u;
  }else{
    *pNum = (i64)u;
  }
  testcase( i==18 );
  testcase( i==19 );
  testcase( i==20 );
  if( (c!=0 && &zNum[i]<zEnd) || (i==0 && zStart==zNum) || i>19*incr ){
    /* zNum is empty or contains non-numeric text or is longer
    ** than 19 digits (thus guaranteeing that it is too large) */
    return 1;
  }else if( i<19*incr ){
    /* Less than 19 digits, so we know that it fits in 64 bits */
    assert( u<=LARGEST_INT64 );
    return 0;
  }else{

    /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */

    c = compare2pow63(zNum, incr);
    if( c<0 ){
      /* zNum is less than 9223372036854775808 so it fits */
      assert( u<=LARGEST_INT64 );
      return 0;
    }else if( c>0 ){
      /* zNum is greater than 9223372036854775808 so it overflows */
      return 1;
    }else{
      /* zNum is exactly 9223372036854775808.  Fits if negative.  The
      ** special case 2 overflow if positive */
      assert( u-1==LARGEST_INT64 );
      assert( (*pNum)==SMALLEST_INT64 );
      return neg ? 0 : 2;
    }
  }
}

/*
** If zNum represents an integer that will fit in 32-bits, then set
** *pValue to that integer and return true.  Otherwise return false.
**
................................................................................
    testcase( sqlite3GlobalConfig.xLog!=0 );
    logBadConnection("invalid");
    return 0;
  }else{
    return 1;
  }
}

/*
** Attempt to add, substract, or multiply the 64-bit signed value iB against
** the other 64-bit signed integer at *pA and store the result in *pA.
** Return 0 on success.  Or if the operation would have resulted in an
** overflow, leave *pA unchanged and return 1.
*/
SQLITE_PRIVATE int sqlite3AddInt64(i64 *pA, i64 iB){
  i64 iA = *pA;
  testcase( iA==0 ); testcase( iA==1 );
  testcase( iB==-1 ); testcase( iB==0 );
  if( iB>=0 ){
    testcase( iA>0 && LARGEST_INT64 - iA == iB );
    testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
    if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
    *pA += iB;
  }else{
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
    if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
    *pA += iB;
  }
  return 0; 
}
SQLITE_PRIVATE int sqlite3SubInt64(i64 *pA, i64 iB){
  testcase( iB==SMALLEST_INT64+1 );
  if( iB==SMALLEST_INT64 ){
    testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
    if( (*pA)>=0 ) return 1;
    *pA -= iB;
    return 0;
  }else{
    return sqlite3AddInt64(pA, -iB);
  }
}
#define TWOPOWER32 (((i64)1)<<32)
#define TWOPOWER31 (((i64)1)<<31)
SQLITE_PRIVATE int sqlite3MulInt64(i64 *pA, i64 iB){
  i64 iA = *pA;
  i64 iA1, iA0, iB1, iB0, r;

  iA1 = iA/TWOPOWER32;
  iA0 = iA % TWOPOWER32;
  iB1 = iB/TWOPOWER32;
  iB0 = iB % TWOPOWER32;
  if( iA1*iB1 != 0 ) return 1;
  assert( iA1*iB0==0 || iA0*iB1==0 );
  r = iA1*iB0 + iA0*iB1;
  testcase( r==(-TWOPOWER31)-1 );
  testcase( r==(-TWOPOWER31) );
  testcase( r==TWOPOWER31 );
  testcase( r==TWOPOWER31-1 );
  if( r<(-TWOPOWER31) || r>=TWOPOWER31 ) return 1;
  r *= TWOPOWER32;
  if( sqlite3AddInt64(&r, iA0*iB0) ) return 1;
  *pA = r;
  return 0;
}

/*
** Compute the absolute value of a 32-bit signed integer, of possible.  Or 
** if the integer has a value of -2147483648, return +2147483647
*/
SQLITE_PRIVATE int sqlite3AbsInt32(int x){
  if( x>=0 ) return x;
  if( x==(int)0x80000000 ) return 0x7fffffff;
  return -x;
}

/************** End of util.c ************************************************/
/************** Begin file hash.c ********************************************/
/*
** 2001 September 22
**
** The author disclaims copyright to this source code.  In place of
................................................................................
#endif

#endif /* !defined(_OS_COMMON_H_) */

/************** End of os_common.h *******************************************/
/************** Continuing where we left off in os_os2.c *********************/

/* Forward references */
typedef struct os2File os2File;         /* The file structure */
typedef struct os2ShmNode os2ShmNode;   /* A shared descritive memory node */
typedef struct os2ShmLink os2ShmLink;   /* A connection to shared-memory */

/*
** The os2File structure is subclass of sqlite3_file specific for the OS/2
** protability layer.
*/

struct os2File {
  const sqlite3_io_methods *pMethod;  /* Always the first entry */
  HFILE h;                  /* Handle for accessing the file */
  int flags;                /* Flags provided to os2Open() */
  int locktype;             /* Type of lock currently held on this file */
  int szChunk;              /* Chunk size configured by FCNTL_CHUNK_SIZE */
  char *zFullPathCp;        /* Full path name of this file */
  os2ShmLink *pShmLink;     /* Instance of shared memory on this file */
};

#define LOCK_TIMEOUT 10L /* the default locking timeout */

/*
** Missing from some versions of the OS/2 toolkit -
** used to allocate from high memory if possible
*/
#ifndef OBJ_ANY
# define OBJ_ANY 0x00000400
#endif

/*****************************************************************************
** The next group of routines implement the I/O methods specified
** by the sqlite3_io_methods object.
******************************************************************************/

/*
** Close a file.
*/
static int os2Close( sqlite3_file *id ){
  APIRET rc;
  os2File *pFile = (os2File*)id;

  assert( id!=0 );
  OSTRACE(( "CLOSE %d (%s)\n", pFile->h, pFile->zFullPathCp ));

  rc = DosClose( pFile->h );

  if( pFile->flags & SQLITE_OPEN_DELETEONCLOSE )
    DosForceDelete( (PSZ)pFile->zFullPathCp );

  free( pFile->zFullPathCp );
  pFile->zFullPathCp = NULL;
  pFile->locktype = NO_LOCK;
  pFile->h = (HFILE)-1;
  pFile->flags = 0;

  OpenCounter( -1 );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
}

/*
** Read data from a file into a buffer.  Return SQLITE_OK if all
** bytes were read successfully and SQLITE_IOERR if anything goes
** wrong.
................................................................................
  return ( rc != NO_ERROR || amt > (int)wrote ) ? SQLITE_FULL : SQLITE_OK;
}

/*
** Truncate an open file to a specified size
*/
static int os2Truncate( sqlite3_file *id, i64 nByte ){
  APIRET rc;
  os2File *pFile = (os2File*)id;
  assert( id!=0 );
  OSTRACE(( "TRUNCATE %d %lld\n", pFile->h, nByte ));
  SimulateIOError( return SQLITE_IOERR_TRUNCATE );

  /* If the user has configured a chunk-size for this file, truncate the
  ** file so that it consists of an integer number of chunks (i.e. the
  ** actual file size after the operation may be larger than the requested
  ** size).
  */
  if( pFile->szChunk ){
    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
  }
  
  rc = DosSetFileSize( pFile->h, nByte );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR_TRUNCATE;
}

#ifdef SQLITE_TEST
/*
** Count the number of fullsyncs and normal syncs.  This is used to test
................................................................................
  switch( op ){
    case SQLITE_FCNTL_LOCKSTATE: {
      *(int*)pArg = ((os2File*)id)->locktype;
      OSTRACE(( "FCNTL_LOCKSTATE %d lock=%d\n",
                ((os2File*)id)->h, ((os2File*)id)->locktype ));
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_CHUNK_SIZE: {
      ((os2File*)id)->szChunk = *(int*)pArg;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SIZE_HINT: {
      sqlite3_int64 sz = *(sqlite3_int64*)pArg;
      SimulateIOErrorBenign(1);
      os2Truncate(id, sz);
      SimulateIOErrorBenign(0);
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_SYNC_OMITTED: {
      return SQLITE_OK;
    }
  }
  return SQLITE_NOTFOUND;
}

/*
** Return the sector size in bytes of the underlying block device for
** the specified file. This is almost always 512 bytes, but may be
................................................................................
**
** SQLite code assumes this function cannot fail. It also assumes that
** if two files are created in the same file-system directory (i.e.
** a database and its journal file) that the sector size will be the
** same for both.
*/
static int os2SectorSize(sqlite3_file *id){
  UNUSED_PARAMETER(id);
  return SQLITE_DEFAULT_SECTOR_SIZE;
}

/*
** Return a vector of device characteristics.
*/
static int os2DeviceCharacteristics(sqlite3_file *id){
  UNUSED_PARAMETER(id);
  return SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN;
}


/*
** Character set conversion objects used by conversion routines.
*/
static UconvObject ucUtf8 = NULL; /* convert between UTF-8 and UCS-2 */
................................................................................
    return out; /* if conversion fails, return the empty string */

  /* determine string for the conversion of UTF-8 which is CP1208 */
  UniStrFromUcs( ucUtf8, out, tempPath, CCHMAXPATH );

  return out;
}


#ifndef SQLITE_OMIT_WAL

/*
** Use main database file for interprocess locking. If un-defined
** a separate file is created for this purpose. The file will be
** used only to set file locks. There will be no data written to it.
*/
#define SQLITE_OS2_NO_WAL_LOCK_FILE     

#if 0
static void _ERR_TRACE( const char *fmt, ... ) {
  va_list  ap;
  va_start(ap, fmt);
  vfprintf(stderr, fmt, ap);
  fflush(stderr);
}
#define ERR_TRACE(rc, msg)        \
        if( (rc) != SQLITE_OK ) _ERR_TRACE msg;
#else
#define ERR_TRACE(rc, msg)
#endif

/*
** Helper functions to obtain and relinquish the global mutex. The
** global mutex is used to protect os2ShmNodeList.
**
** Function os2ShmMutexHeld() is used to assert() that the global mutex 
** is held when required. This function is only used as part of assert() 
** statements. e.g.
**
**   os2ShmEnterMutex()
**     assert( os2ShmMutexHeld() );
**   os2ShmLeaveMutex()
*/
static void os2ShmEnterMutex(void){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
static void os2ShmLeaveMutex(void){
  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
#ifdef SQLITE_DEBUG
static int os2ShmMutexHeld(void) {
  return sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
}
int GetCurrentProcessId(void) {
  PPIB pib;
  DosGetInfoBlocks(NULL, &pib);
  return (int)pib->pib_ulpid;
}
#endif

/*
** Object used to represent a the shared memory area for a single log file.
** When multiple threads all reference the same log-summary, each thread has
** its own os2File object, but they all point to a single instance of this 
** object.  In other words, each log-summary is opened only once per process.
**
** os2ShmMutexHeld() must be true when creating or destroying
** this object or while reading or writing the following fields:
**
**      nRef
**      pNext 
**
** The following fields are read-only after the object is created:
** 
**      szRegion
**      hLockFile
**      shmBaseName
**
** Either os2ShmNode.mutex must be held or os2ShmNode.nRef==0 and
** os2ShmMutexHeld() is true when reading or writing any other field
** in this structure.
**
*/
struct os2ShmNode {
  sqlite3_mutex *mutex;      /* Mutex to access this object */
  os2ShmNode *pNext;         /* Next in list of all os2ShmNode objects */

  int szRegion;              /* Size of shared-memory regions */

  int nRegion;               /* Size of array apRegion */
  void **apRegion;           /* Array of pointers to shared-memory regions */

  int nRef;                  /* Number of os2ShmLink objects pointing to this */
  os2ShmLink *pFirst;        /* First os2ShmLink object pointing to this */

  HFILE hLockFile;           /* File used for inter-process memory locking */
  char shmBaseName[1];       /* Name of the memory object !!! must last !!! */
};


/*
** Structure used internally by this VFS to record the state of an
** open shared memory connection.
**
** The following fields are initialized when this object is created and
** are read-only thereafter:
**
**    os2Shm.pShmNode
**    os2Shm.id
**
** All other fields are read/write.  The os2Shm.pShmNode->mutex must be held
** while accessing any read/write fields.
*/
struct os2ShmLink {
  os2ShmNode *pShmNode;      /* The underlying os2ShmNode object */
  os2ShmLink *pNext;         /* Next os2Shm with the same os2ShmNode */
  u32 sharedMask;            /* Mask of shared locks held */
  u32 exclMask;              /* Mask of exclusive locks held */
#ifdef SQLITE_DEBUG
  u8 id;                     /* Id of this connection with its os2ShmNode */
#endif
};


/*
** A global list of all os2ShmNode objects.
**
** The os2ShmMutexHeld() must be true while reading or writing this list.
*/
static os2ShmNode *os2ShmNodeList = NULL;

/*
** Constants used for locking
*/
#ifdef  SQLITE_OS2_NO_WAL_LOCK_FILE
#define OS2_SHM_BASE   (PENDING_BYTE + 0x10000)         /* first lock byte */
#else
#define OS2_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)        /* first lock byte */
#endif

#define OS2_SHM_DMS    (OS2_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */

/*
** Apply advisory locks for all n bytes beginning at ofst.
*/
#define _SHM_UNLCK  1   /* no lock */
#define _SHM_RDLCK  2   /* shared lock, no wait */
#define _SHM_WRLCK  3   /* exlusive lock, no wait */
#define _SHM_WRLCK_WAIT 4 /* exclusive lock, wait */
static int os2ShmSystemLock(
  os2ShmNode *pNode,    /* Apply locks to this open shared-memory segment */
  int lockType,         /* _SHM_UNLCK, _SHM_RDLCK, _SHM_WRLCK or _SHM_WRLCK_WAIT */
  int ofst,             /* Offset to first byte to be locked/unlocked */
  int nByte             /* Number of bytes to lock or unlock */
){
  APIRET rc;
  FILELOCK area;
  ULONG mode, timeout;

  /* Access to the os2ShmNode object is serialized by the caller */
  assert( sqlite3_mutex_held(pNode->mutex) || pNode->nRef==0 );

  mode = 1;     /* shared lock */
  timeout = 0;  /* no wait */
  area.lOffset = ofst;
  area.lRange = nByte;

  switch( lockType ) {
    case _SHM_WRLCK_WAIT:
      timeout = (ULONG)-1;      /* wait forever */
    case _SHM_WRLCK:
      mode = 0;                 /* exclusive lock */
    case _SHM_RDLCK:
      rc = DosSetFileLocks(pNode->hLockFile, 
                           NULL, &area, timeout, mode);
      break;
    /* case _SHM_UNLCK: */
    default:
      rc = DosSetFileLocks(pNode->hLockFile, 
                           &area, NULL, 0, 0);
      break;
  }
                          
  OSTRACE(("SHM-LOCK %d %s %s 0x%08lx\n", 
           pNode->hLockFile,
           rc==SQLITE_OK ? "ok" : "failed",
           lockType==_SHM_UNLCK ? "Unlock" : "Lock",
           rc));

  ERR_TRACE(rc, ("os2ShmSystemLock: %d %s\n", rc, pNode->shmBaseName))

  return ( rc == 0 ) ?  SQLITE_OK : SQLITE_BUSY;
}

/*
** Find an os2ShmNode in global list or allocate a new one, if not found.
**
** This is not a VFS shared-memory method; it is a utility function called
** by VFS shared-memory methods.
*/
static int os2OpenSharedMemory( os2File *fd, int szRegion ) {
  os2ShmLink *pLink;
  os2ShmNode *pNode;
  int cbShmName, rc = SQLITE_OK;
  char shmName[CCHMAXPATH + 30];
#ifndef SQLITE_OS2_NO_WAL_LOCK_FILE
  ULONG action;
#endif
  
  /* We need some additional space at the end to append the region number */
  cbShmName = sprintf(shmName, "\\SHAREMEM\\%s", fd->zFullPathCp );
  if( cbShmName >= CCHMAXPATH-8 )
    return SQLITE_IOERR_SHMOPEN; 

  /* Replace colon in file name to form a valid shared memory name */
  shmName[10+1] = '!';

  /* Allocate link object (we free it later in case of failure) */
  pLink = sqlite3_malloc( sizeof(*pLink) );
  if( !pLink )
    return SQLITE_NOMEM;

  /* Access node list */
  os2ShmEnterMutex();

  /* Find node by it's shared memory base name */
  for( pNode = os2ShmNodeList; 
       pNode && stricmp(shmName, pNode->shmBaseName) != 0; 
       pNode = pNode->pNext )   ;

  /* Not found: allocate a new node */
  if( !pNode ) {
    pNode = sqlite3_malloc( sizeof(*pNode) + cbShmName );
    if( pNode ) {
      memset(pNode, 0, sizeof(*pNode) );
      pNode->szRegion = szRegion;
      pNode->hLockFile = (HFILE)-1;      
      strcpy(pNode->shmBaseName, shmName);

#ifdef SQLITE_OS2_NO_WAL_LOCK_FILE
      if( DosDupHandle(fd->h, &pNode->hLockFile) != 0 ) {
#else
      sprintf(shmName, "%s-lck", fd->zFullPathCp);
      if( DosOpen((PSZ)shmName, &pNode->hLockFile, &action, 0, FILE_NORMAL, 
                  OPEN_ACTION_OPEN_IF_EXISTS | OPEN_ACTION_CREATE_IF_NEW,
                  OPEN_ACCESS_READWRITE | OPEN_SHARE_DENYNONE | 
                  OPEN_FLAGS_NOINHERIT | OPEN_FLAGS_FAIL_ON_ERROR,
                  NULL) != 0 ) {
#endif
        sqlite3_free(pNode);  
        rc = SQLITE_IOERR;
      } else {
        pNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
        if( !pNode->mutex ) {
          sqlite3_free(pNode);  
          rc = SQLITE_NOMEM;
        }
      }   
    } else {
      rc = SQLITE_NOMEM;
    }
    
    if( rc == SQLITE_OK ) {
      pNode->pNext = os2ShmNodeList;
      os2ShmNodeList = pNode;
    } else {
      pNode = NULL;
    }
  } else if( pNode->szRegion != szRegion ) {
    rc = SQLITE_IOERR_SHMSIZE;
    pNode = NULL;
  }

  if( pNode ) {
    sqlite3_mutex_enter(pNode->mutex);

    memset(pLink, 0, sizeof(*pLink));

    pLink->pShmNode = pNode;
    pLink->pNext = pNode->pFirst;
    pNode->pFirst = pLink;
    pNode->nRef++;

    fd->pShmLink = pLink;

    sqlite3_mutex_leave(pNode->mutex);
    
  } else {
    /* Error occured. Free our link object. */
    sqlite3_free(pLink);  
  }

  os2ShmLeaveMutex();

  ERR_TRACE(rc, ("os2OpenSharedMemory: %d  %s\n", rc, fd->zFullPathCp))  
  
  return rc;
}

/*
** Purge the os2ShmNodeList list of all entries with nRef==0.
**
** This is not a VFS shared-memory method; it is a utility function called
** by VFS shared-memory methods.
*/
static void os2PurgeShmNodes( int deleteFlag ) {
  os2ShmNode *pNode;
  os2ShmNode **ppNode;

  os2ShmEnterMutex();
  
  ppNode = &os2ShmNodeList;

  while( *ppNode ) {
    pNode = *ppNode;

    if( pNode->nRef == 0 ) {
      *ppNode = pNode->pNext;   
     
      if( pNode->apRegion ) {
        /* Prevent other processes from resizing the shared memory */
        os2ShmSystemLock(pNode, _SHM_WRLCK_WAIT, OS2_SHM_DMS, 1);

        while( pNode->nRegion-- ) {
#ifdef SQLITE_DEBUG
          int rc = 
#endif          
          DosFreeMem(pNode->apRegion[pNode->nRegion]);

          OSTRACE(("SHM-PURGE pid-%d unmap region=%d %s\n",
                  (int)GetCurrentProcessId(), pNode->nRegion,
                  rc == 0 ? "ok" : "failed"));
        }

        /* Allow other processes to resize the shared memory */
        os2ShmSystemLock(pNode, _SHM_UNLCK, OS2_SHM_DMS, 1);

        sqlite3_free(pNode->apRegion);
      }  

      DosClose(pNode->hLockFile);
      
#ifndef SQLITE_OS2_NO_WAL_LOCK_FILE
      if( deleteFlag ) {
         char fileName[CCHMAXPATH];
         /* Skip "\\SHAREMEM\\" */
         sprintf(fileName, "%s-lck", pNode->shmBaseName + 10);
         /* restore colon */
         fileName[1] = ':';
         
         DosForceDelete(fileName); 
      }
#endif

      sqlite3_mutex_free(pNode->mutex);

      sqlite3_free(pNode);
      
    } else {
      ppNode = &pNode->pNext;
    }
  } 

  os2ShmLeaveMutex();
}

/*
** This function is called to obtain a pointer to region iRegion of the
** shared-memory associated with the database file id. Shared-memory regions
** are numbered starting from zero. Each shared-memory region is szRegion
** bytes in size.
**
** If an error occurs, an error code is returned and *pp is set to NULL.
**
** Otherwise, if the bExtend parameter is 0 and the requested shared-memory
** region has not been allocated (by any client, including one running in a
** separate process), then *pp is set to NULL and SQLITE_OK returned. If
** bExtend is non-zero and the requested shared-memory region has not yet
** been allocated, it is allocated by this function.
**
** If the shared-memory region has already been allocated or is allocated by
** this call as described above, then it is mapped into this processes
** address space (if it is not already), *pp is set to point to the mapped
** memory and SQLITE_OK returned.
*/
static int os2ShmMap(
  sqlite3_file *id,               /* Handle open on database file */
  int iRegion,                    /* Region to retrieve */
  int szRegion,                   /* Size of regions */
  int bExtend,                    /* True to extend block if necessary */
  void volatile **pp              /* OUT: Mapped memory */
){
  PVOID pvTemp;
  void **apRegion;
  os2ShmNode *pNode;
  int n, rc = SQLITE_OK;
  char shmName[CCHMAXPATH];
  os2File *pFile = (os2File*)id;
  
  *pp = NULL;

  if( !pFile->pShmLink )
    rc = os2OpenSharedMemory( pFile, szRegion );
  
  if( rc == SQLITE_OK ) {
    pNode = pFile->pShmLink->pShmNode ;
    
    sqlite3_mutex_enter(pNode->mutex);
    
    assert( szRegion==pNode->szRegion );

    /* Unmapped region ? */
    if( iRegion >= pNode->nRegion ) {
      /* Prevent other processes from resizing the shared memory */
      os2ShmSystemLock(pNode, _SHM_WRLCK_WAIT, OS2_SHM_DMS, 1);

      apRegion = sqlite3_realloc(
        pNode->apRegion, (iRegion + 1) * sizeof(apRegion[0]));

      if( apRegion ) {
        pNode->apRegion = apRegion;

        while( pNode->nRegion <= iRegion ) {
          sprintf(shmName, "%s-%u", 
                  pNode->shmBaseName, pNode->nRegion);

          if( DosGetNamedSharedMem(&pvTemp, (PSZ)shmName, 
                PAG_READ | PAG_WRITE) != NO_ERROR ) {
            if( !bExtend )
              break;

            if( DosAllocSharedMem(&pvTemp, (PSZ)shmName, szRegion,
                  PAG_READ | PAG_WRITE | PAG_COMMIT | OBJ_ANY) != NO_ERROR && 
                DosAllocSharedMem(&pvTemp, (PSZ)shmName, szRegion,
                  PAG_READ | PAG_WRITE | PAG_COMMIT) != NO_ERROR ) { 
              rc = SQLITE_NOMEM;
              break;
            }
          }

          apRegion[pNode->nRegion++] = pvTemp;
        }

        /* zero out remaining entries */ 
        for( n = pNode->nRegion; n <= iRegion; n++ )
          pNode->apRegion[n] = NULL;

        /* Return this region (maybe zero) */
        *pp = pNode->apRegion[iRegion];
      } else {
        rc = SQLITE_NOMEM;
      }

      /* Allow other processes to resize the shared memory */
      os2ShmSystemLock(pNode, _SHM_UNLCK, OS2_SHM_DMS, 1);
      
    } else {
      /* Region has been mapped previously */
      *pp = pNode->apRegion[iRegion];
    }

    sqlite3_mutex_leave(pNode->mutex);
  } 

  ERR_TRACE(rc, ("os2ShmMap: %s iRgn = %d, szRgn = %d, bExt = %d : %d\n", 
                 pFile->zFullPathCp, iRegion, szRegion, bExtend, rc))
          
  return rc;
}

/*
** Close a connection to shared-memory.  Delete the underlying
** storage if deleteFlag is true.
**
** If there is no shared memory associated with the connection then this
** routine is a harmless no-op.
*/
static int os2ShmUnmap(
  sqlite3_file *id,               /* The underlying database file */
  int deleteFlag                  /* Delete shared-memory if true */
){
  os2File *pFile = (os2File*)id;
  os2ShmLink *pLink = pFile->pShmLink;
  
  if( pLink ) {
    int nRef = -1;
    os2ShmLink **ppLink;
    os2ShmNode *pNode = pLink->pShmNode;

    sqlite3_mutex_enter(pNode->mutex);
    
    for( ppLink = &pNode->pFirst;
         *ppLink && *ppLink != pLink;
         ppLink = &(*ppLink)->pNext )   ;
         
    assert(*ppLink);

    if( *ppLink ) {
      *ppLink = pLink->pNext;
      nRef = --pNode->nRef;
    } else {
      ERR_TRACE(1, ("os2ShmUnmap: link not found ! %s\n", 
                    pNode->shmBaseName))
    }
    
    pFile->pShmLink = NULL;
    sqlite3_free(pLink);

    sqlite3_mutex_leave(pNode->mutex);
    
    if( nRef == 0 )
      os2PurgeShmNodes( deleteFlag );
  }

  return SQLITE_OK;
}

/*
** Change the lock state for a shared-memory segment.
**
** Note that the relationship between SHAREd and EXCLUSIVE locks is a little
** different here than in posix.  In xShmLock(), one can go from unlocked
** to shared and back or from unlocked to exclusive and back.  But one may
** not go from shared to exclusive or from exclusive to shared.
*/
static int os2ShmLock(
  sqlite3_file *id,          /* Database file holding the shared memory */
  int ofst,                  /* First lock to acquire or release */
  int n,                     /* Number of locks to acquire or release */
  int flags                  /* What to do with the lock */
){
  u32 mask;                             /* Mask of locks to take or release */
  int rc = SQLITE_OK;                   /* Result code */
  os2File *pFile = (os2File*)id;
  os2ShmLink *p = pFile->pShmLink;      /* The shared memory being locked */
  os2ShmLink *pX;                       /* For looping over all siblings */
  os2ShmNode *pShmNode = p->pShmNode;   /* Our node */
  
  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
  assert( n>=1 );
  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );

  mask = (u32)((1U<<(ofst+n)) - (1U<<ofst));
  assert( n>1 || mask==(1<<ofst) );


  sqlite3_mutex_enter(pShmNode->mutex);

  if( flags & SQLITE_SHM_UNLOCK ){
    u32 allMask = 0; /* Mask of locks held by siblings */

    /* See if any siblings hold this same lock */
    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
      if( pX==p ) continue;
      assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
      allMask |= pX->sharedMask;
    }

    /* Unlock the system-level locks */
    if( (mask & allMask)==0 ){
      rc = os2ShmSystemLock(pShmNode, _SHM_UNLCK, ofst+OS2_SHM_BASE, n);
    }else{
      rc = SQLITE_OK;
    }

    /* Undo the local locks */
    if( rc==SQLITE_OK ){
      p->exclMask &= ~mask;
      p->sharedMask &= ~mask;
    } 
  }else if( flags & SQLITE_SHM_SHARED ){
    u32 allShared = 0;  /* Union of locks held by connections other than "p" */

    /* Find out which shared locks are already held by sibling connections.
    ** If any sibling already holds an exclusive lock, go ahead and return
    ** SQLITE_BUSY.
    */
    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
      if( (pX->exclMask & mask)!=0 ){
        rc = SQLITE_BUSY;
        break;
      }
      allShared |= pX->sharedMask;
    }

    /* Get shared locks at the system level, if necessary */
    if( rc==SQLITE_OK ){
      if( (allShared & mask)==0 ){
        rc = os2ShmSystemLock(pShmNode, _SHM_RDLCK, ofst+OS2_SHM_BASE, n);
      }else{
        rc = SQLITE_OK;
      }
    }

    /* Get the local shared locks */
    if( rc==SQLITE_OK ){
      p->sharedMask |= mask;
    }
  }else{
    /* Make sure no sibling connections hold locks that will block this
    ** lock.  If any do, return SQLITE_BUSY right away.
    */
    for(pX=pShmNode->pFirst; pX; pX=pX->pNext){
      if( (pX->exclMask & mask)!=0 || (pX->sharedMask & mask)!=0 ){
        rc = SQLITE_BUSY;
        break;
      }
    }
  
    /* Get the exclusive locks at the system level.  Then if successful
    ** also mark the local connection as being locked.
    */
    if( rc==SQLITE_OK ){
      rc = os2ShmSystemLock(pShmNode, _SHM_WRLCK, ofst+OS2_SHM_BASE, n);
      if( rc==SQLITE_OK ){
        assert( (p->sharedMask & mask)==0 );
        p->exclMask |= mask;
      }
    }
  }

  sqlite3_mutex_leave(pShmNode->mutex);
  
  OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %03x,%03x %s\n",
           p->id, (int)GetCurrentProcessId(), p->sharedMask, p->exclMask,
           rc ? "failed" : "ok"));

  ERR_TRACE(rc, ("os2ShmLock: ofst = %d, n = %d, flags = 0x%x -> %d \n", 
                 ofst, n, flags, rc))
                  
  return rc; 
}

/*
** Implement a memory barrier or memory fence on shared memory.
**
** All loads and stores begun before the barrier must complete before
** any load or store begun after the barrier.
*/
static void os2ShmBarrier(
  sqlite3_file *id                /* Database file holding the shared memory */
){
  UNUSED_PARAMETER(id);
  os2ShmEnterMutex();
  os2ShmLeaveMutex();
}

#else
# define os2ShmMap     0
# define os2ShmLock    0
# define os2ShmBarrier 0
# define os2ShmUnmap   0
#endif /* #ifndef SQLITE_OMIT_WAL */


/*
** This vector defines all the methods that can operate on an
** sqlite3_file for os2.
*/
static const sqlite3_io_methods os2IoMethod = {
  2,                              /* iVersion */
  os2Close,                       /* xClose */
  os2Read,                        /* xRead */



  os2Write,                       /* xWrite */
  os2Truncate,                    /* xTruncate */

  os2Sync,                        /* xSync */
  os2FileSize,                    /* xFileSize */

  os2Lock,                        /* xLock */
  os2Unlock,                      /* xUnlock */
  os2CheckReservedLock,           /* xCheckReservedLock */
  os2FileControl,                 /* xFileControl */
  os2SectorSize,                  /* xSectorSize */
  os2DeviceCharacteristics,       /* xDeviceCharacteristics */
  os2ShmMap,                      /* xShmMap */
  os2ShmLock,                     /* xShmLock */
  os2ShmBarrier,                  /* xShmBarrier */
  os2ShmUnmap                     /* xShmUnmap */
};


/***************************************************************************
** Here ends the I/O methods that form the sqlite3_io_methods object.
**
** The next block of code implements the VFS methods.
****************************************************************************/

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at pVfs->mxPathname characters.
*/
static int getTempname(int nBuf, char *zBuf ){
  static const char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  PSZ zTempPathCp;      
  char zTempPath[CCHMAXPATH];
  ULONG ulDriveNum, ulDriveMap;
  
  /* It's odd to simulate an io-error here, but really this is just
  ** using the io-error infrastructure to test that SQLite handles this
  ** function failing. 
  */
  SimulateIOError( return SQLITE_IOERR );

  if( sqlite3_temp_directory ) {


    sqlite3_snprintf(CCHMAXPATH-30, zTempPath, "%s", sqlite3_temp_directory);
  } else if( DosScanEnv( (PSZ)"TEMP",   &zTempPathCp ) == NO_ERROR ||
             DosScanEnv( (PSZ)"TMP",    &zTempPathCp ) == NO_ERROR ||
             DosScanEnv( (PSZ)"TMPDIR", &zTempPathCp ) == NO_ERROR ) {

    char *zTempPathUTF = convertCpPathToUtf8( (char *)zTempPathCp );
    sqlite3_snprintf(CCHMAXPATH-30, zTempPath, "%s", zTempPathUTF);
    free( zTempPathUTF );
  } else if( DosQueryCurrentDisk( &ulDriveNum, &ulDriveMap ) == NO_ERROR ) {
    zTempPath[0] = (char)('A' + ulDriveNum - 1);
    zTempPath[1] = ':'; 
    zTempPath[2] = '\0'; 
  } else {
    zTempPath[0] = '\0'; 
  }
  


  /* Strip off a trailing slashes or backslashes, otherwise we would get *
   * multiple (back)slashes which causes DosOpen() to fail.              *
   * Trailing spaces are not allowed, either.                            */
  j = sqlite3Strlen30(zTempPath);
  while( j > 0 && ( zTempPath[j-1] == '\\' || zTempPath[j-1] == '/' || 
                    zTempPath[j-1] == ' ' ) ){
    j--;
  }
  zTempPath[j] = '\0';

  
  /* We use 20 bytes to randomize the name */
  sqlite3_snprintf(nBuf-22, zBuf,




                   "%s\\"SQLITE_TEMP_FILE_PREFIX, zTempPath);

  j = sqlite3Strlen30(zBuf);
  sqlite3_randomness( 20, &zBuf[j] );
  for( i = 0; i < 20; i++, j++ ){
    zBuf[j] = zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
  }
  zBuf[j] = 0;

  OSTRACE(( "TEMP FILENAME: %s\n", zBuf ));
  return SQLITE_OK;
}


/*
** Turn a relative pathname into a full pathname.  Write the full
................................................................................
  const char *zRelative,      /* Possibly relative input path */
  int nFull,                  /* Size of output buffer in bytes */
  char *zFull                 /* Output buffer */
){
  char *zRelativeCp = convertUtf8PathToCp( zRelative );
  char zFullCp[CCHMAXPATH] = "\0";
  char *zFullUTF;
  APIRET rc = DosQueryPathInfo( (PSZ)zRelativeCp, FIL_QUERYFULLNAME, 
                                zFullCp, CCHMAXPATH );
  free( zRelativeCp );
  zFullUTF = convertCpPathToUtf8( zFullCp );
  sqlite3_snprintf( nFull, zFull, zFullUTF );
  free( zFullUTF );
  return rc == NO_ERROR ? SQLITE_OK : SQLITE_IOERR;
}


/*
** Open a file.
*/
static int os2Open(
  sqlite3_vfs *pVfs,            /* Not used */
  const char *zName,            /* Name of the file (UTF-8) */
  sqlite3_file *id,             /* Write the SQLite file handle here */
  int flags,                    /* Open mode flags */
  int *pOutFlags                /* Status return flags */
){
  HFILE h;

  ULONG ulOpenFlags = 0;
  ULONG ulOpenMode = 0;
  ULONG ulAction = 0;
  ULONG rc;
  os2File *pFile = (os2File*)id;

  const char *zUtf8Name = zName;
  char *zNameCp;
  char  zTmpname[CCHMAXPATH];

  int isExclusive  = (flags & SQLITE_OPEN_EXCLUSIVE);
  int isCreate     = (flags & SQLITE_OPEN_CREATE);
  int isReadWrite  = (flags & SQLITE_OPEN_READWRITE);
#ifndef NDEBUG
  int isDelete     = (flags & SQLITE_OPEN_DELETEONCLOSE);
  int isReadonly   = (flags & SQLITE_OPEN_READONLY);
  int eType        = (flags & 0xFFFFFF00);
  int isOpenJournal = (isCreate && (
        eType==SQLITE_OPEN_MASTER_JOURNAL 
     || eType==SQLITE_OPEN_MAIN_JOURNAL 
     || eType==SQLITE_OPEN_WAL
  ));
#endif

  UNUSED_PARAMETER(pVfs);
  assert( id!=0 );

  /* Check the following statements are true: 
  **
  **   (a) Exactly one of the READWRITE and READONLY flags must be set, and 
  **   (b) if CREATE is set, then READWRITE must also be set, and
  **   (c) if EXCLUSIVE is set, then CREATE must also be set.
  **   (d) if DELETEONCLOSE is set, then CREATE must also be set.
  */
  assert((isReadonly==0 || isReadWrite==0) && (isReadWrite || isReadonly));
  assert(isCreate==0 || isReadWrite);
  assert(isExclusive==0 || isCreate);
  assert(isDelete==0 || isCreate);

  /* The main DB, main journal, WAL file and master journal are never 
  ** automatically deleted. Nor are they ever temporary files.  */
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_DB );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MAIN_JOURNAL );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_MASTER_JOURNAL );
  assert( (!isDelete && zName) || eType!=SQLITE_OPEN_WAL );

  /* Assert that the upper layer has set one of the "file-type" flags. */
  assert( eType==SQLITE_OPEN_MAIN_DB      || eType==SQLITE_OPEN_TEMP_DB 
       || eType==SQLITE_OPEN_MAIN_JOURNAL || eType==SQLITE_OPEN_TEMP_JOURNAL 
       || eType==SQLITE_OPEN_SUBJOURNAL   || eType==SQLITE_OPEN_MASTER_JOURNAL 
       || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
  );

  memset( pFile, 0, sizeof(*pFile) );
  pFile->h = (HFILE)-1;

  /* If the second argument to this function is NULL, generate a 
  ** temporary file name to use 
  */
  if( !zUtf8Name ){
    assert(isDelete && !isOpenJournal);
    rc = getTempname(CCHMAXPATH, zTmpname);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    zUtf8Name = zTmpname;
  }







  if( isReadWrite ){
    ulOpenMode |= OPEN_ACCESS_READWRITE;

  }else{
    ulOpenMode |= OPEN_ACCESS_READONLY;

  }







  /* Open in random access mode for possibly better speed.  Allow full
  ** sharing because file locks will provide exclusive access when needed.
  ** The handle should not be inherited by child processes and we don't 
  ** want popups from the critical error handler.
  */
  ulOpenMode |= OPEN_FLAGS_RANDOM | OPEN_SHARE_DENYNONE | 
                OPEN_FLAGS_NOINHERIT | OPEN_FLAGS_FAIL_ON_ERROR;


  /* SQLITE_OPEN_EXCLUSIVE is used to make sure that a new file is 
  ** created. SQLite doesn't use it to indicate "exclusive access" 
  ** as it is usually understood.
  */
  if( isExclusive ){
    /* Creates a new file, only if it does not already exist. */
    /* If the file exists, it fails. */
    ulOpenFlags |= OPEN_ACTION_CREATE_IF_NEW | OPEN_ACTION_FAIL_IF_EXISTS;


  }else if( isCreate ){












    /* Open existing file, or create if it doesn't exist */
    ulOpenFlags |= OPEN_ACTION_CREATE_IF_NEW | OPEN_ACTION_OPEN_IF_EXISTS;
  }else{


    /* Opens a file, only if it exists. */
    ulOpenFlags |= OPEN_ACTION_FAIL_IF_NEW | OPEN_ACTION_OPEN_IF_EXISTS;
  }






  zNameCp = convertUtf8PathToCp( zUtf8Name );
  rc = DosOpen( (PSZ)zNameCp,
                &h,
                &ulAction,
                0L,

                FILE_NORMAL,
                ulOpenFlags,
                ulOpenMode,
                (PEAOP2)NULL );
  free( zNameCp );

  if( rc != NO_ERROR ){
    OSTRACE(( "OPEN Invalid handle rc=%d: zName=%s, ulAction=%#lx, ulFlags=%#lx, ulMode=%#lx\n",
              rc, zUtf8Name, ulAction, ulOpenFlags, ulOpenMode ));

    if( isReadWrite ){
      return os2Open( pVfs, zName, id,
                      ((flags|SQLITE_OPEN_READONLY)&~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE)),



                      pOutFlags );
    }else{
      return SQLITE_CANTOPEN;
    }
  }

  if( pOutFlags ){
    *pOutFlags = isReadWrite ? SQLITE_OPEN_READWRITE : SQLITE_OPEN_READONLY;
  }

  os2FullPathname( pVfs, zUtf8Name, sizeof( zTmpname ), zTmpname );
  pFile->zFullPathCp = convertUtf8PathToCp( zTmpname );
  pFile->pMethod = &os2IoMethod;
  pFile->flags = flags;
  pFile->h = h;

  OpenCounter(+1);
  OSTRACE(( "OPEN %d pOutFlags=%d\n", pFile->h, pOutFlags ));
  return SQLITE_OK;
}

/*
** Delete the named file.
*/
static int os2Delete(
  sqlite3_vfs *pVfs,                     /* Not used on os2 */
  const char *zFilename,                 /* Name of file to delete */
  int syncDir                            /* Not used on os2 */
){
  APIRET rc;
  char *zFilenameCp;
  SimulateIOError( return SQLITE_IOERR_DELETE );
  zFilenameCp = convertUtf8PathToCp( zFilename );
  rc = DosDelete( (PSZ)zFilenameCp );
  free( zFilenameCp );
  OSTRACE(( "DELETE \"%s\"\n", zFilename ));
  return (rc == NO_ERROR ||
          rc == ERROR_FILE_NOT_FOUND ||
          rc == ERROR_PATH_NOT_FOUND ) ? SQLITE_OK : SQLITE_IOERR_DELETE;
}

/*
** Check the existance and status of a file.
*/
static int os2Access(
  sqlite3_vfs *pVfs,        /* Not used on os2 */
  const char *zFilename,    /* Name of file to check */
  int flags,                /* Type of test to make on this file */
  int *pOut                 /* Write results here */
){
  APIRET rc;
  FILESTATUS3 fsts3ConfigInfo;

  char *zFilenameCp;

  UNUSED_PARAMETER(pVfs);
  SimulateIOError( return SQLITE_IOERR_ACCESS; );
  
  zFilenameCp = convertUtf8PathToCp( zFilename );
  rc = DosQueryPathInfo( (PSZ)zFilenameCp, FIL_STANDARD,
                         &fsts3ConfigInfo, sizeof(FILESTATUS3) );
  free( zFilenameCp );
  OSTRACE(( "ACCESS fsts3ConfigInfo.attrFile=%d flags=%d rc=%d\n",
            fsts3ConfigInfo.attrFile, flags, rc ));

  switch( flags ){
    case SQLITE_ACCESS_EXISTS:
      /* For an SQLITE_ACCESS_EXISTS query, treat a zero-length file
      ** as if it does not exist.
      */
      if( fsts3ConfigInfo.cbFile == 0 ) 
        rc = ERROR_FILE_NOT_FOUND;
      break;
    case SQLITE_ACCESS_READ:


      break;
    case SQLITE_ACCESS_READWRITE:
      if( fsts3ConfigInfo.attrFile & FILE_READONLY )

        rc = ERROR_ACCESS_DENIED;
      break;
    default:
      rc = ERROR_FILE_NOT_FOUND;
      assert( !"Invalid flags argument" );
  }

  *pOut = (rc == NO_ERROR);
  OSTRACE(( "ACCESS %s flags %d: rc=%d\n", zFilename, flags, *pOut ));

  return SQLITE_OK;
}


#ifndef SQLITE_OMIT_LOAD_EXTENSION
/*
** Interfaces for opening a shared library, finding entry points
................................................................................
** within the shared library, and closing the shared library.
*/
/*
** Interfaces for opening a shared library, finding entry points
** within the shared library, and closing the shared library.
*/
static void *os2DlOpen(sqlite3_vfs *pVfs, const char *zFilename){

  HMODULE hmod;
  APIRET rc;
  char *zFilenameCp = convertUtf8PathToCp(zFilename);
  rc = DosLoadModule(NULL, 0, (PSZ)zFilenameCp, &hmod);
  free(zFilenameCp);
  return rc != NO_ERROR ? 0 : (void*)hmod;
}
/*
** A no-op since the error code is returned on the DosLoadModule call.
** os2Dlopen returns zero if DosLoadModule is not successful.
*/
static void os2DlError(sqlite3_vfs *pVfs, int nBuf, char *zBufOut){
/* no-op */
}
static void (*os2DlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol))(void){
  PFN pfn;
  APIRET rc;
  rc = DosQueryProcAddr((HMODULE)pHandle, 0L, (PSZ)zSymbol, &pfn);
  if( rc != NO_ERROR ){
    /* if the symbol itself was not found, search again for the same
     * symbol with an extra underscore, that might be needed depending
     * on the calling convention */
    char _zSymbol[256] = "_";
    strncat(_zSymbol, zSymbol, 254);
    rc = DosQueryProcAddr((HMODULE)pHandle, 0L, (PSZ)_zSymbol, &pfn);
  }
  return rc != NO_ERROR ? 0 : (void(*)(void))pfn;
}
static void os2DlClose(sqlite3_vfs *pVfs, void *pHandle){
  DosFreeModule((HMODULE)pHandle);
}
#else /* if SQLITE_OMIT_LOAD_EXTENSION is defined: */
  #define os2DlOpen 0
  #define os2DlError 0
................................................................................
*/
static int os2Randomness(sqlite3_vfs *pVfs, int nBuf, char *zBuf ){
  int n = 0;
#if defined(SQLITE_TEST)
  n = nBuf;
  memset(zBuf, 0, nBuf);
#else
  int i;                           
  PPIB ppib;
  PTIB ptib;
  DATETIME dt; 

  static unsigned c = 0;
  /* Ordered by variation probability */
  static ULONG svIdx[6] = { QSV_MS_COUNT, QSV_TIME_LOW,
                            QSV_MAXPRMEM, QSV_MAXSHMEM,
                            QSV_TOTAVAILMEM, QSV_TOTRESMEM };


  /* 8 bytes; timezone and weekday don't increase the randomness much */
  if( (int)sizeof(dt)-3 <= nBuf - n ){


    c += 0x0100;
    DosGetDateTime(&dt);
    dt.year = (USHORT)((dt.year - 1900) | c);
    memcpy(&zBuf[n], &dt, sizeof(dt)-3);
    n += sizeof(dt)-3;
  }

  /* 4 bytes; PIDs and TIDs are 16 bit internally, so combine them */
  if( (int)sizeof(ULONG) <= nBuf - n ){

    DosGetInfoBlocks(&ptib, &ppib);
    *(PULONG)&zBuf[n] = MAKELONG(ppib->pib_ulpid,
                                 ptib->tib_ptib2->tib2_ultid);
    n += sizeof(ULONG);
  }







  /* Up to 6 * 4 bytes; variables depend on the system state */
  for( i = 0; i < 6 && (int)sizeof(ULONG) <= nBuf - n; i++ ){
    DosQuerySysInfo(svIdx[i], svIdx[i], 



                    (PULONG)&zBuf[n], sizeof(ULONG));
    n += sizeof(ULONG);
  } 













#endif

  return n;
}

/*
** Sleep for a little while.  Return the amount of time slept.
................................................................................
** returned from sqlite3OsCurrentTime().  This is used for testing.
*/
#ifdef SQLITE_TEST
SQLITE_API int sqlite3_current_time = 0;
#endif

/*
** Find the current time (in Universal Coordinated Time).  Write into *piNow
** the current time and date as a Julian Day number times 86_400_000.  In
** other words, write into *piNow the number of milliseconds since the Julian
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
** proleptic Gregorian calendar.
**
** On success, return 0.  Return 1 if the time and date cannot be found.
*/
static int os2CurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *piNow){
#ifdef SQLITE_TEST
  static const sqlite3_int64 unixEpoch = 24405875*(sqlite3_int64)8640000;
#endif
  int year, month, datepart, timepart;
 
  DATETIME dt;
  DosGetDateTime( &dt );

  year = dt.year;
  month = dt.month;

  /* Calculations from http://www.astro.keele.ac.uk/~rno/Astronomy/hjd.html
  ** http://www.astro.keele.ac.uk/~rno/Astronomy/hjd-0.1.c
  ** Calculate the Julian days
  */
  datepart = (int)dt.day - 32076 +
    1461*(year + 4800 + (month - 14)/12)/4 +
    367*(month - 2 - (month - 14)/12*12)/12 -
    3*((year + 4900 + (month - 14)/12)/100)/4;

  /* Time in milliseconds, hours to noon added */
  timepart = 12*3600*1000 + dt.hundredths*10 + dt.seconds*1000 +
    ((int)dt.minutes + dt.timezone)*60*1000 + dt.hours*3600*1000;


  *piNow = (sqlite3_int64)datepart*86400*1000 + timepart;
   
#ifdef SQLITE_TEST
  if( sqlite3_current_time ){

    *piNow = 1000*(sqlite3_int64)sqlite3_current_time + unixEpoch;
  }
#endif

  UNUSED_PARAMETER(pVfs);
  return 0;
}

/*
** Find the current time (in Universal Coordinated Time).  Write the
** current time and date as a Julian Day number into *prNow and
** return 0.  Return 1 if the time and date cannot be found.
*/
static int os2CurrentTime( sqlite3_vfs *pVfs, double *prNow ){
  int rc;
  sqlite3_int64 i;
  rc = os2CurrentTimeInt64(pVfs, &i);
  if( !rc ){
    *prNow = i/86400000.0;
  }
  return rc;
}

/*
** The idea is that this function works like a combination of
** GetLastError() and FormatMessage() on windows (or errno and
** strerror_r() on unix). After an error is returned by an OS
** function, SQLite calls this function with zBuf pointing to
** a buffer of nBuf bytes. The OS layer should populate the
** buffer with a nul-terminated UTF-8 encoded error message
** describing the last IO error to have occurred within the calling
** thread.
**
** If the error message is too large for the supplied buffer,
** it should be truncated. The return value of xGetLastError
** is zero if the error message fits in the buffer, or non-zero
** otherwise (if the message was truncated). If non-zero is returned,
** then it is not necessary to include the nul-terminator character
** in the output buffer.
**
** Not supplying an error message will have no adverse effect
** on SQLite. It is fine to have an implementation that never
** returns an error message:
**
**   int xGetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
**     assert(zBuf[0]=='\0');
**     return 0;
**   }
**
** However if an error message is supplied, it will be incorporated
** by sqlite into the error message available to the user using
** sqlite3_errmsg(), possibly making IO errors easier to debug.
*/
static int os2GetLastError(sqlite3_vfs *pVfs, int nBuf, char *zBuf){
  assert(zBuf[0]=='\0');
  return 0;
}

/*
** Initialize and deinitialize the operating system interface.
*/
SQLITE_API int sqlite3_os_init(void){
  static sqlite3_vfs os2Vfs = {
    3,                 /* iVersion */
    sizeof(os2File),   /* szOsFile */
    CCHMAXPATH,        /* mxPathname */
    0,                 /* pNext */
    "os2",             /* zName */
    0,                 /* pAppData */

    os2Open,           /* xOpen */
................................................................................
    os2DlError,        /* xDlError */
    os2DlSym,          /* xDlSym */
    os2DlClose,        /* xDlClose */
    os2Randomness,     /* xRandomness */
    os2Sleep,          /* xSleep */
    os2CurrentTime,    /* xCurrentTime */
    os2GetLastError,   /* xGetLastError */
    os2CurrentTimeInt64, /* xCurrentTimeInt64 */
    0,                 /* xSetSystemCall */
    0,                 /* xGetSystemCall */
    0                  /* xNextSystemCall */
  };
  sqlite3_vfs_register(&os2Vfs, 1);
  initUconvObjects();
/*  sqlite3OSTrace = 1; */
  return SQLITE_OK;
}
SQLITE_API int sqlite3_os_end(void){
  freeUconvObjects();
  return SQLITE_OK;
}

................................................................................
typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  unixInodeInfo *pInode;              /* Info about locks on this inode */
  int h;                              /* The file descriptor */
  int dirfd;                          /* File descriptor for the directory */
  unsigned char eFileLock;            /* The type of lock held on this fd */
  unsigned char ctrlFlags;            /* Behavioral bits.  UNIXFILE_* flags */
  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */

  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
#if SQLITE_ENABLE_LOCKING_STYLE
  int openFlags;                      /* The flags specified at open() */
#endif
#if SQLITE_ENABLE_LOCKING_STYLE || defined(__APPLE__)
................................................................................
  ** it is larger than the struct CrashFile defined in test6.c.
  */
  char aPadding[32];
#endif
};

/*
** Allowed values for the unixFile.ctrlFlags bitmask:
*/
#define UNIXFILE_EXCL   0x01     /* Connections from one process only */
#define UNIXFILE_RDONLY 0x02     /* Connection is read only */

/*
** Include code that is common to all os_*.c files
*/
/************** Include os_common.h in the middle of os_unix.c ***************/
/************** Begin file os_common.h ***************************************/
/*
................................................................................
#ifndef O_NOFOLLOW
# define O_NOFOLLOW 0
#endif
#ifndef O_BINARY
# define O_BINARY 0
#endif

/*
** The threadid macro resolves to the thread-id or to 0.  Used for
** testing and debugging only.
*/
#if SQLITE_THREADSAFE
#define threadid pthread_self()
#else
#define threadid 0
#endif

/*
** Many system calls are accessed through pointer-to-functions so that
** they may be overridden at runtime to facilitate fault injection during
** testing and sandboxing.  The following array holds the names and pointers
** to all overrideable system calls.
*/
static struct unix_syscall {
  const char *zName;            /* Name of the sytem call */
  sqlite3_syscall_ptr pCurrent; /* Current value of the system call */
  sqlite3_syscall_ptr pDefault; /* Default value */
} aSyscall[] = {
  { "open",         (sqlite3_syscall_ptr)open,       0  },
#define osOpen      ((int(*)(const char*,int,int))aSyscall[0].pCurrent)

  { "close",        (sqlite3_syscall_ptr)close,      0  },
#define osClose     ((int(*)(int))aSyscall[1].pCurrent)

  { "access",       (sqlite3_syscall_ptr)access,     0  },
#define osAccess    ((int(*)(const char*,int))aSyscall[2].pCurrent)

  { "getcwd",       (sqlite3_syscall_ptr)getcwd,     0  },
#define osGetcwd    ((char*(*)(char*,size_t))aSyscall[3].pCurrent)

  { "stat",         (sqlite3_syscall_ptr)stat,       0  },
#define osStat      ((int(*)(const char*,struct stat*))aSyscall[4].pCurrent)

/*
** The DJGPP compiler environment looks mostly like Unix, but it
** lacks the fcntl() system call.  So redefine fcntl() to be something
** that always succeeds.  This means that locking does not occur under
** DJGPP.  But it is DOS - what did you expect?
*/
#ifdef __DJGPP__

  { "fstat",        0,                 0  },
#define osFstat(a,b,c)    0
#else     
  { "fstat",        (sqlite3_syscall_ptr)fstat,      0  },
#define osFstat     ((int(*)(int,struct stat*))aSyscall[5].pCurrent)
#endif

  { "ftruncate",    (sqlite3_syscall_ptr)ftruncate,  0  },
#define osFtruncate ((int(*)(int,off_t))aSyscall[6].pCurrent)

  { "fcntl",        (sqlite3_syscall_ptr)fcntl,      0  },
#define osFcntl     ((int(*)(int,int,...))aSyscall[7].pCurrent)

  { "read",         (sqlite3_syscall_ptr)read,       0  },
#define osRead      ((ssize_t(*)(int,void*,size_t))aSyscall[8].pCurrent)

#if defined(USE_PREAD) || defined(SQLITE_ENABLE_LOCKING_STYLE)
  { "pread",        (sqlite3_syscall_ptr)pread,      0  },
#else
  { "pread",        (sqlite3_syscall_ptr)0,          0  },
#endif
#define osPread     ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[9].pCurrent)

#if defined(USE_PREAD64)
  { "pread64",      (sqlite3_syscall_ptr)pread64,    0  },
#else
  { "pread64",      (sqlite3_syscall_ptr)0,          0  },
#endif
#define osPread64   ((ssize_t(*)(int,void*,size_t,off_t))aSyscall[10].pCurrent)

  { "write",        (sqlite3_syscall_ptr)write,      0  },
#define osWrite     ((ssize_t(*)(int,const void*,size_t))aSyscall[11].pCurrent)

#if defined(USE_PREAD) || defined(SQLITE_ENABLE_LOCKING_STYLE)
  { "pwrite",       (sqlite3_syscall_ptr)pwrite,     0  },
#else
  { "pwrite",       (sqlite3_syscall_ptr)0,          0  },
#endif
#define osPwrite    ((ssize_t(*)(int,const void*,size_t,off_t))\
                    aSyscall[12].pCurrent)

#if defined(USE_PREAD64)
  { "pwrite64",     (sqlite3_syscall_ptr)pwrite64,   0  },
#else
  { "pwrite64",     (sqlite3_syscall_ptr)0,          0  },
#endif
#define osPwrite64  ((ssize_t(*)(int,const void*,size_t,off_t))\
                    aSyscall[13].pCurrent)

#if SQLITE_ENABLE_LOCKING_STYLE
  { "fchmod",       (sqlite3_syscall_ptr)fchmod,     0  },
#define osFchmod    ((int(*)(int,mode_t))aSyscall[14].pCurrent)
#endif

#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
  { "fallocate",    (sqlite3_syscall_ptr)posix_fallocate,  0 },
#else
  { "fallocate",    (sqlite3_syscall_ptr)0,                0 },
#endif
#define osFallocate ((int(*)(int,off_t,off_t))aSyscall[15].pCurrent)

}; /* End of the overrideable system calls */

/*


** This is the xSetSystemCall() method of sqlite3_vfs for all of the
** "unix" VFSes.  Return SQLITE_OK opon successfully updating the
** system call pointer, or SQLITE_NOTFOUND if there is no configurable
** system call named zName.
*/
static int unixSetSystemCall(
  sqlite3_vfs *pNotUsed,        /* The VFS pointer.  Not used */
  const char *zName,            /* Name of system call to override */
  sqlite3_syscall_ptr pNewFunc  /* Pointer to new system call value */
){
  unsigned int i;
  int rc = SQLITE_NOTFOUND;

  UNUSED_PARAMETER(pNotUsed);
  if( zName==0 ){
    /* If no zName is given, restore all system calls to their default
    ** settings and return NULL
    */
    rc = SQLITE_OK;

    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
      if( aSyscall[i].pDefault ){
        aSyscall[i].pCurrent = aSyscall[i].pDefault;
      }
    }
  }else{


    /* If zName is specified, operate on only the one system call
    ** specified.
    */
    for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
      if( strcmp(zName, aSyscall[i].zName)==0 ){
        if( aSyscall[i].pDefault==0 ){
          aSyscall[i].pDefault = aSyscall[i].pCurrent;
        }
        rc = SQLITE_OK;
        if( pNewFunc==0 ) pNewFunc = aSyscall[i].pDefault;
        aSyscall[i].pCurrent = pNewFunc;
        break;
      }
    }
  }
  return rc;
}

/*
** Return the value of a system call.  Return NULL if zName is not a
** recognized system call name.  NULL is also returned if the system call
** is currently undefined.
*/
static sqlite3_syscall_ptr unixGetSystemCall(
  sqlite3_vfs *pNotUsed,
  const char *zName
){
  unsigned int i;

  UNUSED_PARAMETER(pNotUsed);
  for(i=0; i<sizeof(aSyscall)/sizeof(aSyscall[0]); i++){
    if( strcmp(zName, aSyscall[i].zName)==0 ) return aSyscall[i].pCurrent;
  }
  return 0;
}

/*
** Return the name of the first system call after zName.  If zName==NULL
** then return the name of the first system call.  Return NULL if zName
** is the last system call or if zName is not the name of a valid
** system call.
*/
static const char *unixNextSystemCall(sqlite3_vfs *p, const char *zName){
  int i = -1;

  UNUSED_PARAMETER(p);
  if( zName ){
    for(i=0; i<ArraySize(aSyscall)-1; i++){
      if( strcmp(zName, aSyscall[i].zName)==0 ) break;
    }
  }
  for(i++; i<ArraySize(aSyscall); i++){
    if( aSyscall[i].pCurrent!=0 ) return aSyscall[i].zName;
  }
  return 0;
}

/*
** Retry open() calls that fail due to EINTR
*/
static int robust_open(const char *z, int f, int m){
  int rc;
  do{ rc = osOpen(z,f,m); }while( rc<0 && errno==EINTR );
  return rc;
}

/*
** Helper functions to obtain and relinquish the global mutex. The
** global mutex is used to protect the unixInodeInfo and
** vxworksFileId objects used by this file, all of which may be 
** shared by multiple threads.
**
................................................................................
  int s;
  int savedErrno;
  if( op==F_GETLK ){
    zOpName = "GETLK";
  }else if( op==F_SETLK ){
    zOpName = "SETLK";
  }else{
    s = osFcntl(fd, op, p);
    sqlite3DebugPrintf("fcntl unknown %d %d %d\n", fd, op, s);
    return s;
  }
  if( p->l_type==F_RDLCK ){
    zType = "RDLCK";
  }else if( p->l_type==F_WRLCK ){
    zType = "WRLCK";
  }else if( p->l_type==F_UNLCK ){
    zType = "UNLCK";
  }else{
    assert( 0 );
  }
  assert( p->l_whence==SEEK_SET );
  s = osFcntl(fd, op, p);
  savedErrno = errno;
  sqlite3DebugPrintf("fcntl %d %d %s %s %d %d %d %d\n",
     threadid, fd, zOpName, zType, (int)p->l_start, (int)p->l_len,
     (int)p->l_pid, s);
  if( s==(-1) && op==F_SETLK && (p->l_type==F_RDLCK || p->l_type==F_WRLCK) ){
    struct flock l2;
    l2 = *p;
    osFcntl(fd, F_GETLK, &l2);
    if( l2.l_type==F_RDLCK ){
      zType = "RDLCK";
    }else if( l2.l_type==F_WRLCK ){
      zType = "WRLCK";
    }else if( l2.l_type==F_UNLCK ){
      zType = "UNLCK";
    }else{
................................................................................
    }
    sqlite3DebugPrintf("fcntl-failure-reason: %s %d %d %d\n",
       zType, (int)l2.l_start, (int)l2.l_len, (int)l2.l_pid);
  }
  errno = savedErrno;
  return s;
}
#undef osFcntl
#define osFcntl lockTrace
#endif /* SQLITE_LOCK_TRACE */

/*
** Retry ftruncate() calls that fail due to EINTR
*/
static int robust_ftruncate(int h, sqlite3_int64 sz){
  int rc;
  do{ rc = osFtruncate(h,sz); }while( rc<0 && errno==EINTR );
  return rc;
}

/*
** This routine translates a standard POSIX errno code into something
** useful to the clients of the sqlite3 functions.  Specifically, it is
** intended to translate a variety of "try again" errors into SQLITE_BUSY
** and a variety of "please close the file descriptor NOW" errors into 
** SQLITE_IOERR
** 
** Errors during initialization of locks, or file system support for locks,
** should handle ENOLCK, ENOTSUP, EOPNOTSUPP separately.
*/
static int sqliteErrorFromPosixError(int posixError, int sqliteIOErr) {
  switch (posixError) {
#if 0
  /* At one point this code was not commented out. In theory, this branch
  ** should never be hit, as this function should only be called after
  ** a locking-related function (i.e. fcntl()) has returned non-zero with
  ** the value of errno as the first argument. Since a system call has failed,
  ** errno should be non-zero.
  **
  ** Despite this, if errno really is zero, we still don't want to return
  ** SQLITE_OK. The system call failed, and *some* SQLite error should be
  ** propagated back to the caller. Commenting this branch out means errno==0
  ** will be handled by the "default:" case below.
  */
  case 0: 
    return SQLITE_OK;
#endif

  case EAGAIN:
  case ETIMEDOUT:
  case EBUSY:
  case EINTR:
  case ENOLCK:  
    /* random NFS retry error, unless during file system support 
     * introspection, in which it actually means what it says */
................................................................................
	(sqliteIOErr == SQLITE_IOERR_CHECKRESERVEDLOCK) ){
      return SQLITE_BUSY;
    }
    /* else fall through */
  case EPERM: 
    return SQLITE_PERM;
    
  /* EDEADLK is only possible if a call to fcntl(F_SETLKW) is made. And
  ** this module never makes such a call. And the code in SQLite itself 
  ** asserts that SQLITE_IOERR_BLOCKED is never returned. For these reasons
  ** this case is also commented out. If the system does set errno to EDEADLK,
  ** the default SQLITE_IOERR_XXX code will be returned. */
#if 0
  case EDEADLK:
    return SQLITE_IOERR_BLOCKED;
#endif
    
#if EOPNOTSUPP!=ENOTSUP
  case EOPNOTSUPP: 
    /* something went terribly awry, unless during file system support 
     * introspection, in which it actually means what it says */
#endif
#ifdef ENOTSUP
................................................................................
** A single inode can have multiple file descriptors, so each unixFile
** structure contains a pointer to an instance of this object and this
** object keeps a count of the number of unixFile pointing to it.
*/
struct unixInodeInfo {
  struct unixFileId fileId;       /* The lookup key */
  int nShared;                    /* Number of SHARED locks held */
  unsigned char eFileLock;        /* One of SHARED_LOCK, RESERVED_LOCK etc. */
  unsigned char bProcessLock;     /* An exclusive process lock is held */
  int nRef;                       /* Number of pointers to this structure */
  unixShmNode *pShmNode;          /* Shared memory associated with this inode */
  int nLock;                      /* Number of outstanding file locks */
  UnixUnusedFd *pUnused;          /* Unused file descriptors to close */
  unixInodeInfo *pNext;           /* List of all unixInodeInfo objects */
  unixInodeInfo *pPrev;           /*    .... doubly linked */
#if defined(SQLITE_ENABLE_LOCKING_STYLE)
................................................................................

/*
** A lists of all unixInodeInfo objects.
*/
static unixInodeInfo *inodeList = 0;

/*
**
** This function - unixLogError_x(), is only ever called via the macro
** unixLogError().
**
** It is invoked after an error occurs in an OS function and errno has been
** set. It logs a message using sqlite3_log() containing the current value of
** errno and, if possible, the human-readable equivalent from strerror() or
** strerror_r().
**
** The first argument passed to the macro should be the error code that
** will be returned to SQLite (e.g. SQLITE_IOERR_DELETE, SQLITE_CANTOPEN). 
** The two subsequent arguments should be the name of the OS function that
** failed (e.g. "unlink", "open") and the the associated file-system path,
** if any.
*/
#define unixLogError(a,b,c)     unixLogErrorAtLine(a,b,c,__LINE__)
static int unixLogErrorAtLine(
  int errcode,                    /* SQLite error code */
  const char *zFunc,              /* Name of OS function that failed */
  const char *zPath,              /* File path associated with error */
  int iLine                       /* Source line number where error occurred */
){
  char *zErr;                     /* Message from strerror() or equivalent */
  int iErrno = errno;             /* Saved syscall error number */

  /* If this is not a threadsafe build (SQLITE_THREADSAFE==0), then use
  ** the strerror() function to obtain the human-readable error message
  ** equivalent to errno. Otherwise, use strerror_r().
  */ 
#if SQLITE_THREADSAFE && defined(HAVE_STRERROR_R)
  char aErr[80];
  memset(aErr, 0, sizeof(aErr));
  zErr = aErr;

  /* If STRERROR_R_CHAR_P (set by autoconf scripts) or __USE_GNU is defined,
  ** assume that the system provides the the GNU version of strerror_r() that 
  ** returns a pointer to a buffer containing the error message. That pointer 
  ** may point to aErr[], or it may point to some static storage somewhere. 
  ** Otherwise, assume that the system provides the POSIX version of 
  ** strerror_r(), which always writes an error message into aErr[].
  **
  ** If the code incorrectly assumes that it is the POSIX version that is
  ** available, the error message will often be an empty string. Not a
  ** huge problem. Incorrectly concluding that the GNU version is available 
  ** could lead to a segfault though.
  */
#if defined(STRERROR_R_CHAR_P) || defined(__USE_GNU)
  zErr = 
# endif
  strerror_r(iErrno, aErr, sizeof(aErr)-1);

#elif SQLITE_THREADSAFE
  /* This is a threadsafe build, but strerror_r() is not available. */
  zErr = "";
#else
  /* Non-threadsafe build, use strerror(). */
  zErr = strerror(iErrno);
#endif

  assert( errcode!=SQLITE_OK );
  if( zPath==0 ) zPath = "";
  sqlite3_log(errcode,
      "os_unix.c:%d: (%d) %s(%s) - %s",
      iLine, iErrno, zFunc, zPath, zErr
  );

  return errcode;
}

/*
** Close a file descriptor.
**
** We assume that close() almost always works, since it is only in a
** very sick application or on a very sick platform that it might fail.
** If it does fail, simply leak the file descriptor, but do log the
** error.
**
** Note that it is not safe to retry close() after EINTR since the
** file descriptor might have already been reused by another thread.
** So we don't even try to recover from an EINTR.  Just log the error
** and move on.
*/
static void robust_close(unixFile *pFile, int h, int lineno){
  if( osClose(h) ){
    unixLogErrorAtLine(SQLITE_IOERR_CLOSE, "close",
                       pFile ? pFile->zPath : 0, lineno);
  }
}

/*
** Close all file descriptors accumuated in the unixInodeInfo->pUnused list.
*/ 
static void closePendingFds(unixFile *pFile){

  unixInodeInfo *pInode = pFile->pInode;

  UnixUnusedFd *p;
  UnixUnusedFd *pNext;
  for(p=pInode->pUnused; p; p=pNext){
    pNext = p->pNext;
    robust_close(pFile, p->fd, __LINE__);





    sqlite3_free(p);
  }

  pInode->pUnused = 0;

}

/*
** Release a unixInodeInfo structure previously allocated by findInodeInfo().
**
** The mutex entered using the unixEnterMutex() function must be held
** when this function is called.
*/
static void releaseInodeInfo(unixFile *pFile){
  unixInodeInfo *pInode = pFile->pInode;
  assert( unixMutexHeld() );
  if( ALWAYS(pInode) ){
    pInode->nRef--;
    if( pInode->nRef==0 ){
      assert( pInode->pShmNode==0 );
      closePendingFds(pFile);
      if( pInode->pPrev ){
        assert( pInode->pPrev->pNext==pInode );
        pInode->pPrev->pNext = pInode->pNext;
................................................................................

  assert( unixMutexHeld() );

  /* Get low-level information about the file that we can used to
  ** create a unique name for the file.
  */
  fd = pFile->h;
  rc = osFstat(fd, &statbuf);
  if( rc!=0 ){
    pFile->lastErrno = errno;
#ifdef EOVERFLOW
    if( pFile->lastErrno==EOVERFLOW ) return SQLITE_NOLFS;
#endif
    return SQLITE_IOERR;
  }
................................................................................
  ** prior to accessing the inode number.  The one byte written is
  ** an ASCII 'S' character which also happens to be the first byte
  ** in the header of every SQLite database.  In this way, if there
  ** is a race condition such that another thread has already populated
  ** the first page of the database, no damage is done.
  */
  if( statbuf.st_size==0 && (pFile->fsFlags & SQLITE_FSFLAGS_IS_MSDOS)!=0 ){
    do{ rc = osWrite(fd, "S", 1); }while( rc<0 && errno==EINTR );
    if( rc!=1 ){
      pFile->lastErrno = errno;
      return SQLITE_IOERR;
    }
    rc = osFstat(fd, &statbuf);
    if( rc!=0 ){
      pFile->lastErrno = errno;
      return SQLITE_IOERR;
    }
  }
#endif

................................................................................
  if( pFile->pInode->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it.
  */
#ifndef __DJGPP__
  if( !reserved && !pFile->pInode->bProcessLock ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    if( osFcntl(pFile->h, F_GETLK, &lock) ){

      rc = SQLITE_IOERR_CHECKRESERVEDLOCK;
      pFile->lastErrno = errno;
    } else if( lock.l_type!=F_UNLCK ){
      reserved = 1;
    }
  }
#endif
  
  unixLeaveMutex();
  OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));

  *pResOut = reserved;
  return rc;
}

/*
** Attempt to set a system-lock on the file pFile.  The lock is 
** described by pLock.
**
** If the pFile was opened read/write from unix-excl, then the only lock
** ever obtained is an exclusive lock, and it is obtained exactly once
** the first time any lock is attempted.  All subsequent system locking
** operations become no-ops.  Locking operations still happen internally,
** in order to coordinate access between separate database connections
** within this process, but all of that is handled in memory and the
** operating system does not participate.
**
** This function is a pass-through to fcntl(F_SETLK) if pFile is using
** any VFS other than "unix-excl" or if pFile is opened on "unix-excl"
** and is read-only.
**
** Zero is returned if the call completes successfully, or -1 if a call
** to fcntl() fails. In this case, errno is set appropriately (by fcntl()).
*/
static int unixFileLock(unixFile *pFile, struct flock *pLock){
  int rc;
  unixInodeInfo *pInode = pFile->pInode;
  assert( unixMutexHeld() );
  assert( pInode!=0 );
  if( ((pFile->ctrlFlags & UNIXFILE_EXCL)!=0 || pInode->bProcessLock)
   && ((pFile->ctrlFlags & UNIXFILE_RDONLY)==0)
  ){
    if( pInode->bProcessLock==0 ){
      struct flock lock;
      assert( pInode->nLock==0 );
      lock.l_whence = SEEK_SET;
      lock.l_start = SHARED_FIRST;
      lock.l_len = SHARED_SIZE;
      lock.l_type = F_WRLCK;
      rc = osFcntl(pFile->h, F_SETLK, &lock);
      if( rc<0 ) return rc;
      pInode->bProcessLock = 1;
      pInode->nLock++;
    }else{
      rc = 0;
    }
  }else{
    rc = osFcntl(pFile->h, F_SETLK, pLock);
  }
  return rc;
}

/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
................................................................................
  ** locking a random byte from a range, concurrent SHARED locks may exist
  ** even if the locking primitive used is always a write-lock.
  */
  int rc = SQLITE_OK;
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode = pFile->pInode;
  struct flock lock;

  int tErrno = 0;

  assert( pFile );
  OSTRACE(("LOCK    %d %s was %s(%s,%d) pid=%d (unix)\n", pFile->h,
      azFileLock(eFileLock), azFileLock(pFile->eFileLock),
      azFileLock(pInode->eFileLock), pInode->nShared , getpid()));

................................................................................
  lock.l_len = 1L;
  lock.l_whence = SEEK_SET;
  if( eFileLock==SHARED_LOCK 
      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
  ){
    lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    if( unixFileLock(pFile, &lock) ){

      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);

      if( rc!=SQLITE_BUSY ){
        pFile->lastErrno = tErrno;
      }
      goto end_lock;
    }
  }


  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( eFileLock==SHARED_LOCK ){
    assert( pInode->nShared==0 );
    assert( pInode->eFileLock==0 );
    assert( rc==SQLITE_OK );

    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    if( unixFileLock(pFile, &lock) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
    }

    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( unixFileLock(pFile, &lock) && rc==SQLITE_OK ){

      /* This could happen with a network mount */
      tErrno = errno;
      rc = SQLITE_IOERR_UNLOCK; 


    }



    if( rc ){


      if( rc!=SQLITE_BUSY ){
        pFile->lastErrno = tErrno;
      }
      goto end_lock;
    }else{
      pFile->eFileLock = SHARED_LOCK;
      pInode->nLock++;
      pInode->nShared = 1;
    }
  }else if( eFileLock==EXCLUSIVE_LOCK && pInode->nShared>1 ){
    /* We are trying for an exclusive lock but another thread in this
................................................................................
  }else{
    /* The request was for a RESERVED or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    assert( 0!=pFile->eFileLock );
    lock.l_type = F_WRLCK;


    assert( eFileLock==RESERVED_LOCK || eFileLock==EXCLUSIVE_LOCK );
    if( eFileLock==RESERVED_LOCK ){
      lock.l_start = RESERVED_BYTE;

      lock.l_len = 1L;
    }else{
      lock.l_start = SHARED_FIRST;
      lock.l_len = SHARED_SIZE;



    }



    if( unixFileLock(pFile, &lock) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);

      if( rc!=SQLITE_BUSY ){
        pFile->lastErrno = tErrno;
      }
    }
  }
  

#ifndef NDEBUG
................................................................................
** 
** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
** the byte range is divided into 2 parts and the first part is unlocked then
** set to a read lock, then the other part is simply unlocked.  This works 
** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to 
** remove the write lock on a region when a read lock is set.
*/
static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode;
  struct flock lock;
  int rc = SQLITE_OK;
  int h;


  assert( pFile );
  OSTRACE(("UNLOCK  %d %d was %d(%d,%d) pid=%d (unix)\n", pFile->h, eFileLock,
      pFile->eFileLock, pFile->pInode->eFileLock, pFile->pInode->nShared,
      getpid()));

  assert( eFileLock<=SHARED_LOCK );
................................................................................
    ** write lock until the rest is covered by a read lock:
    **  1:   [WWWWW]
    **  2:   [....W]
    **  3:   [RRRRW]
    **  4:   [RRRR.]
    */
    if( eFileLock==SHARED_LOCK ){

#if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE
      (void)handleNFSUnlock;
      assert( handleNFSUnlock==0 );
#endif
#if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE
      if( handleNFSUnlock ){
        int tErrno;               /* Error code from system call errors */
        off_t divSize = SHARED_SIZE - 1;
        
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( unixFileLock(pFile, &lock)==(-1) ){
          tErrno = errno;
          rc = SQLITE_IOERR_UNLOCK;
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( unixFileLock(pFile, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST+divSize;
        lock.l_len = SHARED_SIZE-divSize;
        if( unixFileLock(pFile, &lock)==(-1) ){
          tErrno = errno;
          rc = SQLITE_IOERR_UNLOCK;
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
      }else
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
      {
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        if( unixFileLock(pFile, &lock) ){
          /* In theory, the call to unixFileLock() cannot fail because another
          ** process is holding an incompatible lock. If it does, this 
          ** indicates that the other process is not following the locking
          ** protocol. If this happens, return SQLITE_IOERR_RDLOCK. Returning
          ** SQLITE_BUSY would confuse the upper layer (in practice it causes 
          ** an assert to fail). */ 
          rc = SQLITE_IOERR_RDLOCK;

          pFile->lastErrno = errno;

          goto end_unlock;
        }
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( unixFileLock(pFile, &lock)==0 ){
      pInode->eFileLock = SHARED_LOCK;
    }else{

      rc = SQLITE_IOERR_UNLOCK;

      pFile->lastErrno = errno;

      goto end_unlock;
    }
  }
  if( eFileLock==NO_LOCK ){
    /* Decrement the shared lock counter.  Release the lock using an
    ** OS call only when all threads in this same process have released
    ** the lock.
................................................................................
    if( pInode->nShared==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( unixFileLock(pFile, &lock)==0 ){
        pInode->eFileLock = NO_LOCK;
      }else{

        rc = SQLITE_IOERR_UNLOCK;

	pFile->lastErrno = errno;

        pInode->eFileLock = NO_LOCK;
        pFile->eFileLock = NO_LOCK;
      }
    }

    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */
    pInode->nLock--;
    assert( pInode->nLock>=0 );
    if( pInode->nLock==0 ){
      closePendingFds(pFile);



    }
  }
	
end_unlock:
  unixLeaveMutex();
  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
  return rc;
................................................................................
** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int eFileLock){
  return posixUnlock(id, eFileLock, 0);
}

/*
** This function performs the parts of the "close file" operation 
** common to all locking schemes. It closes the directory and file
** handles, if they are valid, and sets all fields of the unixFile
** structure to 0.
................................................................................
**
** It is *not* necessary to hold the mutex when this routine is called,
** even on VxWorks.  A mutex will be acquired on VxWorks by the
** vxworksReleaseFileId() routine.
*/
static int closeUnixFile(sqlite3_file *id){
  unixFile *pFile = (unixFile*)id;

  if( pFile->dirfd>=0 ){





    robust_close(pFile, pFile->dirfd, __LINE__);
    pFile->dirfd=-1;
  }

  if( pFile->h>=0 ){
    robust_close(pFile, pFile->h, __LINE__);
    pFile->h = -1;



  }

#if OS_VXWORKS
  if( pFile->pId ){
    if( pFile->isDelete ){
      unlink(pFile->pId->zCanonicalName);
    }
    vxworksReleaseFileId(pFile->pId);
    pFile->pId = 0;
  }
#endif
  OSTRACE(("CLOSE   %-3d\n", pFile->h));
  OpenCounter(-1);
  sqlite3_free(pFile->pUnused);
  memset(pFile, 0, sizeof(unixFile));

  return SQLITE_OK;
}

/*
** Close a file.
*/
static int unixClose(sqlite3_file *id){
  int rc = SQLITE_OK;

  unixFile *pFile = (unixFile *)id;
  unixUnlock(id, NO_LOCK);
  unixEnterMutex();

  /* unixFile.pInode is always valid here. Otherwise, a different close
  ** routine (e.g. nolockClose()) would be called instead.
  */
  assert( pFile->pInode->nLock>0 || pFile->pInode->bProcessLock==0 );
  if( ALWAYS(pFile->pInode) && pFile->pInode->nLock ){
    /* If there are outstanding locks, do not actually close the file just
    ** yet because that would clear those locks.  Instead, add the file
    ** descriptor to pInode->pUnused list.  It will be automatically closed 
    ** when the last lock is cleared.
    */
    setPendingFd(pFile);
  }
  releaseInodeInfo(pFile);
  rc = closeUnixFile(id);
  unixLeaveMutex();

  return rc;
}

/************** End of the posix advisory lock implementation *****************
******************************************************************************/

/******************************************************************************
................................................................................
  if( pFile->eFileLock>SHARED_LOCK ){
    /* Either this connection or some other connection in the same process
    ** holds a lock on the file.  No need to check further. */
    reserved = 1;
  }else{
    /* The lock is held if and only if the lockfile exists */
    const char *zLockFile = (const char*)pFile->lockingContext;
    reserved = osAccess(zLockFile, 0)==0;
  }
  OSTRACE(("TEST WR-LOCK %d %d %d (dotlock)\n", pFile->h, rc, reserved));
  *pResOut = reserved;
  return rc;
}

/*
................................................................................
    /* Always update the timestamp on the old file */
    utimes(zLockFile, NULL);
#endif
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  fd = robust_open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
  if( fd<0 ){
    /* failed to open/create the file, someone else may have stolen the lock */
    int tErrno = errno;
    if( EEXIST == tErrno ){
      rc = SQLITE_BUSY;
    } else {
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
    return rc;
  } 
  robust_close(pFile, fd, __LINE__);



  
  /* got it, set the type and return ok */
  pFile->eFileLock = eFileLock;
  return rc;
}

/*
................................................................................
  
  /* To fully unlock the database, delete the lock file */
  assert( eFileLock==NO_LOCK );
  if( unlink(zLockFile) ){
    int rc = 0;
    int tErrno = errno;
    if( ENOENT != tErrno ){
      rc = SQLITE_IOERR_UNLOCK;
    }
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
    return rc; 
  }
  pFile->eFileLock = NO_LOCK;
................................................................................
** only a single process can be reading the database at a time.
**
** Omit this section if SQLITE_ENABLE_LOCKING_STYLE is turned off or if
** compiling for VXWORKS.
*/
#if SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS

/*
** Retry flock() calls that fail with EINTR
*/
#ifdef EINTR
static int robust_flock(int fd, int op){
  int rc;
  do{ rc = flock(fd,op); }while( rc<0 && errno==EINTR );
  return rc;
}
#else
# define robust_flock(a,b) flock(a,b)
#endif
     

/*
** This routine checks if there is a RESERVED lock held on the specified
** file by this or any other process. If such a lock is held, set *pResOut
** to a non-zero value otherwise *pResOut is set to zero.  The return value
** is set to SQLITE_OK unless an I/O error occurs during lock checking.
*/
static int flockCheckReservedLock(sqlite3_file *id, int *pResOut){
................................................................................
  if( pFile->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }
  
  /* Otherwise see if some other process holds it. */
  if( !reserved ){
    /* attempt to get the lock */
    int lrc = robust_flock(pFile->h, LOCK_EX | LOCK_NB);
    if( !lrc ){
      /* got the lock, unlock it */
      lrc = robust_flock(pFile->h, LOCK_UN);
      if ( lrc ) {
        int tErrno = errno;
        /* unlock failed with an error */
        lrc = SQLITE_IOERR_UNLOCK; 
        if( IS_LOCK_ERROR(lrc) ){
          pFile->lastErrno = tErrno;
          rc = lrc;
        }
      }
    } else {
      int tErrno = errno;
................................................................................
  if (pFile->eFileLock > NO_LOCK) {
    pFile->eFileLock = eFileLock;
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  
  if (robust_flock(pFile->h, LOCK_EX | LOCK_NB)) {
    int tErrno = errno;
    /* didn't get, must be busy */
    rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
    if( IS_LOCK_ERROR(rc) ){
      pFile->lastErrno = tErrno;
    }
  } else {
................................................................................
  /* shared can just be set because we always have an exclusive */
  if (eFileLock==SHARED_LOCK) {
    pFile->eFileLock = eFileLock;
    return SQLITE_OK;
  }
  
  /* no, really, unlock. */
  if( robust_flock(pFile->h, LOCK_UN) ){






#ifdef SQLITE_IGNORE_FLOCK_LOCK_ERRORS

    return SQLITE_OK;

#endif /* SQLITE_IGNORE_FLOCK_LOCK_ERRORS */

    return SQLITE_IOERR_UNLOCK;
  }else{
    pFile->eFileLock = NO_LOCK;
    return SQLITE_OK;
  }
}

/*
** Close a file.
................................................................................
        pFile->eFileLock = NO_LOCK;
      }
    }
    if( rc==SQLITE_OK ){
      pInode->nLock--;
      assert( pInode->nLock>=0 );
      if( pInode->nLock==0 ){
        closePendingFds(pFile);
      }
    }
  }
  
  unixLeaveMutex();
  if( rc==SQLITE_OK ) pFile->eFileLock = eFileLock;
  return rc;
................................................................................
 ** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
 ** must be either NO_LOCK or SHARED_LOCK.
 **
 ** If the locking level of the file descriptor is already at or below
 ** the requested locking level, this routine is a no-op.
 */
static int nfsUnlock(sqlite3_file *id, int eFileLock){
  return posixUnlock(id, eFileLock, 1);
}

#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
/*
** The code above is the NFS lock implementation.  The code is specific
** to MacOSX and does not work on other unix platforms.  No alternative
** is available.  
................................................................................
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
  int got;
#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
  i64 newOffset;
#endif
  TIMER_START;
#if defined(USE_PREAD)
  do{ got = osPread(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR );
  SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
  do{ got = osPread64(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR);
  SimulateIOError( got = -1 );
#else
  newOffset = lseek(id->h, offset, SEEK_SET);
  SimulateIOError( newOffset-- );
  if( newOffset!=offset ){
    if( newOffset == -1 ){
      ((unixFile*)id)->lastErrno = errno;
    }else{
      ((unixFile*)id)->lastErrno = 0;			
    }
    return -1;
  }
  do{ got = osRead(id->h, pBuf, cnt); }while( got<0 && errno==EINTR );
#endif
  TIMER_END;
  if( got<0 ){
    ((unixFile*)id)->lastErrno = errno;
  }
  OSTRACE(("READ    %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
  return got;
................................................................................
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
  int got;
#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
  i64 newOffset;
#endif
  TIMER_START;
#if defined(USE_PREAD)
  do{ got = osPwrite(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR );
#elif defined(USE_PREAD64)
  do{ got = osPwrite64(id->h, pBuf, cnt, offset);}while( got<0 && errno==EINTR);
#else
  newOffset = lseek(id->h, offset, SEEK_SET);
  SimulateIOError( newOffset-- );
  if( newOffset!=offset ){
    if( newOffset == -1 ){
      ((unixFile*)id)->lastErrno = errno;
    }else{
      ((unixFile*)id)->lastErrno = 0;			
    }
    return -1;
  }
  do{ got = osWrite(id->h, pBuf, cnt); }while( got<0 && errno==EINTR );
#endif
  TIMER_END;
  if( got<0 ){
    ((unixFile*)id)->lastErrno = errno;
  }

  OSTRACE(("WRITE   %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
................................................................................
  /* If we compiled with the SQLITE_NO_SYNC flag, then syncing is a
  ** no-op
  */
#ifdef SQLITE_NO_SYNC
  rc = SQLITE_OK;
#elif HAVE_FULLFSYNC
  if( fullSync ){
    rc = osFcntl(fd, F_FULLFSYNC, 0);
  }else{
    rc = 1;
  }
  /* If the FULLFSYNC failed, fall back to attempting an fsync().
  ** It shouldn't be possible for fullfsync to fail on the local 
  ** file system (on OSX), so failure indicates that FULLFSYNC
  ** isn't supported for this file system. So, attempt an fsync 
................................................................................

  assert( pFile );
  OSTRACE(("SYNC    %-3d\n", pFile->h));
  rc = full_fsync(pFile->h, isFullsync, isDataOnly);
  SimulateIOError( rc=1 );
  if( rc ){
    pFile->lastErrno = errno;
    return unixLogError(SQLITE_IOERR_FSYNC, "full_fsync", pFile->zPath);
  }
  if( pFile->dirfd>=0 ){

    OSTRACE(("DIRSYNC %-3d (have_fullfsync=%d fullsync=%d)\n", pFile->dirfd,
            HAVE_FULLFSYNC, isFullsync));
#ifndef SQLITE_DISABLE_DIRSYNC
    /* The directory sync is only attempted if full_fsync is
    ** turned off or unavailable.  If a full_fsync occurred above,
    ** then the directory sync is superfluous.
    */
................................................................................
       ** A failed directory sync is not a big deal.  So it seems
       ** better to ignore the error.  Ticket #1657
       */
       /* pFile->lastErrno = errno; */
       /* return SQLITE_IOERR; */
    }
#endif
    /* Only need to sync once, so close the  directory when we are done */
    robust_close(pFile, pFile->dirfd, __LINE__);
    pFile->dirfd = -1;




  }
  return rc;
}

/*
** Truncate an open file to a specified size
*/
................................................................................
  ** actual file size after the operation may be larger than the requested
  ** size).
  */
  if( pFile->szChunk ){
    nByte = ((nByte + pFile->szChunk - 1)/pFile->szChunk) * pFile->szChunk;
  }

  rc = robust_ftruncate(pFile->h, (off_t)nByte);
  if( rc ){
    pFile->lastErrno = errno;
    return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
  }else{
#ifndef NDEBUG
    /* If we are doing a normal write to a database file (as opposed to
    ** doing a hot-journal rollback or a write to some file other than a
    ** normal database file) and we truncate the file to zero length,
    ** that effectively updates the change counter.  This might happen
    ** when restoring a database using the backup API from a zero-length
................................................................................
/*
** Determine the current size of a file in bytes
*/
static int unixFileSize(sqlite3_file *id, i64 *pSize){
  int rc;
  struct stat buf;
  assert( id );
  rc = osFstat(((unixFile*)id)->h, &buf);
  SimulateIOError( rc=1 );
  if( rc!=0 ){
    ((unixFile*)id)->lastErrno = errno;
    return SQLITE_IOERR_FSTAT;
  }
  *pSize = buf.st_size;

................................................................................
** SQLITE_FCNTL_SIZE_HINT operation is a no-op for Unix.
*/
static int fcntlSizeHint(unixFile *pFile, i64 nByte){
  if( pFile->szChunk ){
    i64 nSize;                    /* Required file size */
    struct stat buf;              /* Used to hold return values of fstat() */
   
    if( osFstat(pFile->h, &buf) ) return SQLITE_IOERR_FSTAT;

    nSize = ((nByte+pFile->szChunk-1) / pFile->szChunk) * pFile->szChunk;
    if( nSize>(i64)buf.st_size ){

#if defined(HAVE_POSIX_FALLOCATE) && HAVE_POSIX_FALLOCATE
      /* The code below is handling the return value of osFallocate() 
      ** correctly. posix_fallocate() is defined to "returns zero on success, 
      ** or an error number on  failure". See the manpage for details. */
      int err;
      do{
        err = osFallocate(pFile->h, buf.st_size, nSize-buf.st_size);
      }while( err==EINTR );
      if( err ) return SQLITE_IOERR_WRITE;

#else
      /* If the OS does not have posix_fallocate(), fake it. First use
      ** ftruncate() to set the file size, then write a single byte to
      ** the last byte in each block within the extended region. This
      ** is the same technique used by glibc to implement posix_fallocate()
      ** on systems that do not have a real fallocate() system call.
      */
      int nBlk = buf.st_blksize;  /* File-system block size */
      i64 iWrite;                 /* Next offset to write to */


      if( robust_ftruncate(pFile->h, nSize) ){
        pFile->lastErrno = errno;
        return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
      }
      iWrite = ((buf.st_size + 2*nBlk - 1)/nBlk)*nBlk-1;

      while( iWrite<nSize ){
        int nWrite = seekAndWrite(pFile, iWrite, "", 1);


        if( nWrite!=1 ) return SQLITE_IOERR_WRITE;
        iWrite += nBlk;
      }
#endif
    }
  }

  return SQLITE_OK;
}

................................................................................

  /* Shared locks never span more than one byte */
  assert( n==1 || lockType!=F_RDLCK );

  /* Locks are within range */
  assert( n>=1 && n<SQLITE_SHM_NLOCK );

  if( pShmNode->h>=0 ){
    /* Initialize the locking parameters */
    memset(&f, 0, sizeof(f));
    f.l_type = lockType;
    f.l_whence = SEEK_SET;
    f.l_start = ofst;
    f.l_len = n;

    rc = osFcntl(pShmNode->h, F_SETLK, &f);
    rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY;
  }

  /* Update the global lock state and do debug tracing */
#ifdef SQLITE_DEBUG
  { u16 mask;
  OSTRACE(("SHM-LOCK "));
  mask = (1<<(ofst+n)) - (1<<ofst);
  if( rc==SQLITE_OK ){
................................................................................
  unixShmNode *p = pFd->pInode->pShmNode;
  assert( unixMutexHeld() );
  if( p && p->nRef==0 ){
    int i;
    assert( p->pInode==pFd->pInode );
    if( p->mutex ) sqlite3_mutex_free(p->mutex);
    for(i=0; i<p->nRegion; i++){
      if( p->h>=0 ){
        munmap(p->apRegion[i], p->szRegion);
      }else{
        sqlite3_free(p->apRegion[i]);
      }
    }
    sqlite3_free(p->apRegion);
    if( p->h>=0 ){
      robust_close(pFd, p->h, __LINE__);
      p->h = -1;
    }
    p->pInode->pShmNode = 0;
    sqlite3_free(p);
  }
}

/*
** Open a shared-memory area associated with open database file pDbFd.  
................................................................................
** same database file at the same time, database corruption will likely
** result. The SQLITE_SHM_DIRECTORY compile-time option is considered
** "unsupported" and may go away in a future SQLite release.
**
** When opening a new shared-memory file, if no other instances of that
** file are currently open, in this process or in other processes, then
** the file must be truncated to zero length or have its header cleared.
**
** If the original database file (pDbFd) is using the "unix-excl" VFS
** that means that an exclusive lock is held on the database file and
** that no other processes are able to read or write the database.  In
** that case, we do not really need shared memory.  No shared memory
** file is created.  The shared memory will be simulated with heap memory.
*/
static int unixOpenSharedMemory(unixFile *pDbFd){
  struct unixShm *p = 0;          /* The connection to be opened */
  struct unixShmNode *pShmNode;   /* The underlying mmapped file */
  int rc;                         /* Result code */
  unixInodeInfo *pInode;          /* The inode of fd */
  char *zShmFilename;             /* Name of the file used for SHM */
................................................................................
    struct stat sStat;                 /* fstat() info for database file */

    /* Call fstat() to figure out the permissions on the database file. If
    ** a new *-shm file is created, an attempt will be made to create it
    ** with the same permissions. The actual permissions the file is created
    ** with are subject to the current umask setting.
    */
    if( osFstat(pDbFd->h, &sStat) && pInode->bProcessLock==0 ){
      rc = SQLITE_IOERR_FSTAT;
      goto shm_open_err;
    }

#ifdef SQLITE_SHM_DIRECTORY
    nShmFilename = sizeof(SQLITE_SHM_DIRECTORY) + 30;
#else
................................................................................
    pShmNode->pInode = pDbFd->pInode;
    pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
    if( pShmNode->mutex==0 ){
      rc = SQLITE_NOMEM;
      goto shm_open_err;
    }

    if( pInode->bProcessLock==0 ){
      pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT,
                               (sStat.st_mode & 0777));
      if( pShmNode->h<0 ){
        rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
        goto shm_open_err;
      }
  
      /* Check to see if another process is holding the dead-man switch.
      ** If not, truncate the file to zero length. 
      */
      rc = SQLITE_OK;
      if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
        if( robust_ftruncate(pShmNode->h, 0) ){
          rc = unixLogError(SQLITE_IOERR_SHMOPEN, "ftruncate", zShmFilename);
        }
      }
      if( rc==SQLITE_OK ){
        rc = unixShmSystemLock(pShmNode, F_RDLCK, UNIX_SHM_DMS, 1);
      }
      if( rc ) goto shm_open_err;
    }
  }

  /* Make the new connection a child of the unixShmNode */
  p->pShmNode = pShmNode;
#ifdef SQLITE_DEBUG
  p->id = pShmNode->nextShmId++;
#endif
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }

  p = pDbFd->pShm;
  pShmNode = p->pShmNode;
  sqlite3_mutex_enter(pShmNode->mutex);
  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
  assert( pShmNode->pInode==pDbFd->pInode );
  assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );

  if( pShmNode->nRegion<=iRegion ){
    char **apNew;                      /* New apRegion[] array */
    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
    struct stat sStat;                 /* Used by fstat() */

    pShmNode->szRegion = szRegion;

    if( pShmNode->h>=0 ){
      /* The requested region is not mapped into this processes address space.
      ** Check to see if it has been allocated (i.e. if the wal-index file is
      ** large enough to contain the requested region).
      */
      if( osFstat(pShmNode->h, &sStat) ){













        rc = SQLITE_IOERR_SHMSIZE;
        goto shmpage_out;
      }
  
      if( sStat.st_size<nByte ){
        /* The requested memory region does not exist. If bExtend is set to
        ** false, exit early. *pp will be set to NULL and SQLITE_OK returned.
        **
        ** Alternatively, if bExtend is true, use ftruncate() to allocate
        ** the requested memory region.
        */
        if( !bExtend ) goto shmpage_out;
        if( robust_ftruncate(pShmNode->h, nByte) ){
          rc = unixLogError(SQLITE_IOERR_SHMSIZE, "ftruncate",
                            pShmNode->zFilename);
          goto shmpage_out;
        }
      }
    }

    /* Map the requested memory region into this processes address space. */
    apNew = (char **)sqlite3_realloc(
        pShmNode->apRegion, (iRegion+1)*sizeof(char *)
    );
    if( !apNew ){
      rc = SQLITE_IOERR_NOMEM;
      goto shmpage_out;
    }
    pShmNode->apRegion = apNew;
    while(pShmNode->nRegion<=iRegion){
      void *pMem;
      if( pShmNode->h>=0 ){
        pMem = mmap(0, szRegion, PROT_READ|PROT_WRITE, 
            MAP_SHARED, pShmNode->h, pShmNode->nRegion*szRegion
        );
        if( pMem==MAP_FAILED ){
          rc = SQLITE_IOERR;
          goto shmpage_out;
        }
      }else{
        pMem = sqlite3_malloc(szRegion);
        if( pMem==0 ){
          rc = SQLITE_NOMEM;
          goto shmpage_out;
        }
        memset(pMem, 0, szRegion);
      }
      pShmNode->apRegion[pShmNode->nRegion] = pMem;
      pShmNode->nRegion++;
    }
  }

shmpage_out:
................................................................................
  assert( ofst>=0 && ofst+n<=SQLITE_SHM_NLOCK );
  assert( n>=1 );
  assert( flags==(SQLITE_SHM_LOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED)
       || flags==(SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE) );
  assert( n==1 || (flags & SQLITE_SHM_EXCLUSIVE)!=0 );
  assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );

  mask = (1<<(ofst+n)) - (1<<ofst);
  assert( n>1 || mask==(1<<ofst) );
  sqlite3_mutex_enter(pShmNode->mutex);
  if( flags & SQLITE_SHM_UNLOCK ){
    u16 allMask = 0; /* Mask of locks held by siblings */

................................................................................

  /* If pShmNode->nRef has reached 0, then close the underlying
  ** shared-memory file, too */
  unixEnterMutex();
  assert( pShmNode->nRef>0 );
  pShmNode->nRef--;
  if( pShmNode->nRef==0 ){
    if( deleteFlag && pShmNode->h>=0 ) unlink(pShmNode->zFilename);
    unixShmPurge(pDbFd);
  }
  unixLeaveMutex();

  return SQLITE_OK;
}

................................................................................
  ** Test byte-range lock using fcntl(). If the call succeeds, 
  ** assume that the file-system supports POSIX style locks. 
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
    if( strcmp(fsInfo.f_fstypename, "nfs")==0 ){
      return &nfsIoMethods;
    } else {
      return &posixIoMethods;
    }
  }else{
    return &dotlockIoMethods;
................................................................................
  /* Test if fcntl() is supported and use POSIX style locks.
  ** Otherwise fall back to the named semaphore method.
  */
  lockInfo.l_len = 1;
  lockInfo.l_start = 0;
  lockInfo.l_whence = SEEK_SET;
  lockInfo.l_type = F_RDLCK;
  if( osFcntl(pNew->h, F_GETLK, &lockInfo)!=-1 ) {
    return &posixIoMethods;
  }else{
    return &semIoMethods;
  }
}
static const sqlite3_io_methods 
  *(*const autolockIoFinder)(const char*,unixFile*) = autolockIoFinderImpl;
................................................................................
static int fillInUnixFile(
  sqlite3_vfs *pVfs,      /* Pointer to vfs object */
  int h,                  /* Open file descriptor of file being opened */
  int dirfd,              /* Directory file descriptor */
  sqlite3_file *pId,      /* Write to the unixFile structure here */
  const char *zFilename,  /* Name of the file being opened */
  int noLock,             /* Omit locking if true */
  int isDelete,           /* Delete on close if true */
  int isReadOnly          /* True if the file is opened read-only */
){
  const sqlite3_io_methods *pLockingStyle;
  unixFile *pNew = (unixFile *)pId;
  int rc = SQLITE_OK;

  assert( pNew->pInode==NULL );

................................................................................
#else
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->dirfd = dirfd;

  pNew->zPath = zFilename;
  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
    pNew->ctrlFlags = UNIXFILE_EXCL;
  }else{
    pNew->ctrlFlags = 0;
  }
  if( isReadOnly ){
    pNew->ctrlFlags |= UNIXFILE_RDONLY;
  }

#if OS_VXWORKS
  pNew->pId = vxworksFindFileId(zFilename);
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
................................................................................
      ** handle h - as it is guaranteed that no posix locks will be released
      ** by doing so.
      **
      ** If scenario (a) caused the error then things are not so safe. The
      ** implicit assumption here is that if fstat() fails, things are in
      ** such bad shape that dropping a lock or two doesn't matter much.
      */
      robust_close(pNew, h, __LINE__);
      h = -1;
    }
    unixLeaveMutex();
  }

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
  else if( pLockingStyle == &afpIoMethods ){
................................................................................
      pCtx->dbPath = zFilename;
      pCtx->reserved = 0;
      srandomdev();
      unixEnterMutex();
      rc = findInodeInfo(pNew, &pNew->pInode);
      if( rc!=SQLITE_OK ){
        sqlite3_free(pNew->lockingContext);
        robust_close(pNew, h, __LINE__);
        h = -1;
      }
      unixLeaveMutex();        
    }
  }
#endif

................................................................................
    unixLeaveMutex();
  }
#endif
  
  pNew->lastErrno = 0;
#if OS_VXWORKS
  if( rc!=SQLITE_OK ){
    if( h>=0 ) robust_close(pNew, h, __LINE__);
    h = -1;
    unlink(zFilename);
    isDelete = 0;
  }
  pNew->isDelete = isDelete;
#endif
  if( rc!=SQLITE_OK ){
    if( dirfd>=0 ) robust_close(pNew, dirfd, __LINE__);
    if( h>=0 ) robust_close(pNew, h, __LINE__);
  }else{
    pNew->pMethod = pLockingStyle;
    OpenCounter(+1);
  }
  return rc;
}

................................................................................
  int fd = -1;
  char zDirname[MAX_PATHNAME+1];

  sqlite3_snprintf(MAX_PATHNAME, zDirname, "%s", zFilename);
  for(ii=(int)strlen(zDirname); ii>1 && zDirname[ii]!='/'; ii--);
  if( ii>0 ){
    zDirname[ii] = '\0';
    fd = robust_open(zDirname, O_RDONLY|O_BINARY, 0);
    if( fd>=0 ){
#ifdef FD_CLOEXEC
      osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif
      OSTRACE(("OPENDIR %-3d %s\n", fd, zDirname));
    }
  }
  *pFd = fd;
  return (fd>=0?SQLITE_OK:unixLogError(SQLITE_CANTOPEN_BKPT, "open", zDirname));
}

/*
** Return the name of a directory in which to put temporary files.
** If no suitable temporary file directory can be found, return NULL.
*/
static const char *unixTempFileDir(void){
................................................................................
  struct stat buf;
  const char *zDir = 0;

  azDirs[0] = sqlite3_temp_directory;
  if( !azDirs[1] ) azDirs[1] = getenv("TMPDIR");
  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); zDir=azDirs[i++]){
    if( zDir==0 ) continue;
    if( osStat(zDir, &buf) ) continue;
    if( !S_ISDIR(buf.st_mode) ) continue;
    if( osAccess(zDir, 07) ) continue;
    break;
  }
  return zDir;
}

/*
** Create a temporary file name in zBuf.  zBuf must be allocated
................................................................................
    sqlite3_snprintf(nBuf-17, zBuf, "%s/"SQLITE_TEMP_FILE_PREFIX, zDir);
    j = (int)strlen(zBuf);
    sqlite3_randomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
  }while( osAccess(zBuf,0)==0 );
  return SQLITE_OK;
}

#if SQLITE_ENABLE_LOCKING_STYLE && defined(__APPLE__)
/*
** Routine to transform a unixFile into a proxy-locking unixFile.
** Implementation in the proxy-lock division, but used by unixOpen()
................................................................................
    mode_t openMode;              /* Permissions to create file with */
    rc = findCreateFileMode(zName, flags, &openMode);
    if( rc!=SQLITE_OK ){
      assert( !p->pUnused );
      assert( eType==SQLITE_OPEN_WAL || eType==SQLITE_OPEN_MAIN_JOURNAL );
      return rc;
    }
    fd = robust_open(zName, openFlags, openMode);
    OSTRACE(("OPENX   %-3d %s 0%o\n", fd, zName, openFlags));
    if( fd<0 && errno!=EISDIR && isReadWrite && !isExclusive ){
      /* Failed to open the file for read/write access. Try read-only. */
      flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
      openFlags &= ~(O_RDWR|O_CREAT);
      flags |= SQLITE_OPEN_READONLY;
      openFlags |= O_RDONLY;
      isReadonly = 1;
      fd = robust_open(zName, openFlags, openMode);
    }
    if( fd<0 ){
      rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zName);
      goto open_finished;
    }
  }
  assert( fd>=0 );
  if( pOutFlags ){
    *pOutFlags = flags;
  }
................................................................................
    rc = openDirectory(zPath, &dirfd);
    if( rc!=SQLITE_OK ){
      /* It is safe to close fd at this point, because it is guaranteed not
      ** to be open on a database file. If it were open on a database file,
      ** it would not be safe to close as this would release any locks held
      ** on the file by this process.  */
      assert( eType!=SQLITE_OPEN_MAIN_DB );
      robust_close(p, fd, __LINE__);
      goto open_finished;
    }
  }

#ifdef FD_CLOEXEC
  osFcntl(fd, F_SETFD, osFcntl(fd, F_GETFD, 0) | FD_CLOEXEC);
#endif

  noLock = eType!=SQLITE_OPEN_MAIN_DB;

  
#if defined(__APPLE__) || SQLITE_ENABLE_LOCKING_STYLE
  struct statfs fsInfo;
  if( fstatfs(fd, &fsInfo) == -1 ){
    ((unixFile*)pFile)->lastErrno = errno;
    if( dirfd>=0 ) robust_close(p, dirfd, __LINE__);
    robust_close(p, fd, __LINE__);
    return SQLITE_IOERR_ACCESS;
  }
  if (0 == strncmp("msdos", fsInfo.f_fstypename, 5)) {
    ((unixFile*)pFile)->fsFlags |= SQLITE_FSFLAGS_IS_MSDOS;
  }
#endif
  
................................................................................
        ** on that file that are currently holding advisory locks on it,
        ** then the call to close() will cancel those locks. In practice,
        ** we're assuming that statfs() doesn't fail very often. At least
        ** not while other file descriptors opened by the same process on
        ** the same file are working.  */
        p->lastErrno = errno;
        if( dirfd>=0 ){
          robust_close(p, dirfd, __LINE__);
        }
        robust_close(p, fd, __LINE__);
        rc = SQLITE_IOERR_ACCESS;
        goto open_finished;
      }
      useProxy = !(fsInfo.f_flags&MNT_LOCAL);
    }
    if( useProxy ){
      rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
                          isDelete, isReadonly);
      if( rc==SQLITE_OK ){
        rc = proxyTransformUnixFile((unixFile*)pFile, ":auto:");
        if( rc!=SQLITE_OK ){
          /* Use unixClose to clean up the resources added in fillInUnixFile 
          ** and clear all the structure's references.  Specifically, 
          ** pFile->pMethods will be NULL so sqlite3OsClose will be a no-op 
          */
................................................................................
        }
      }
      goto open_finished;
    }
  }
#endif
  
  rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock,
                      isDelete, isReadonly);
open_finished:
  if( rc!=SQLITE_OK ){
    sqlite3_free(p->pUnused);
  }
  return rc;
}

................................................................................
  const char *zPath,        /* Name of file to be deleted */
  int dirSync               /* If true, fsync() directory after deleting file */
){
  int rc = SQLITE_OK;
  UNUSED_PARAMETER(NotUsed);
  SimulateIOError(return SQLITE_IOERR_DELETE);
  if( unlink(zPath)==(-1) && errno!=ENOENT ){
    return unixLogError(SQLITE_IOERR_DELETE, "unlink", zPath);
  }
#ifndef SQLITE_DISABLE_DIRSYNC
  if( dirSync ){
    int fd;
    rc = openDirectory(zPath, &fd);
    if( rc==SQLITE_OK ){
#if OS_VXWORKS
      if( fsync(fd)==-1 )
#else
      if( fsync(fd) )
#endif
      {
        rc = unixLogError(SQLITE_IOERR_DIR_FSYNC, "fsync", zPath);
      }
      robust_close(0, fd, __LINE__);


    }
  }
#endif
  return rc;
}

/*
................................................................................
    case SQLITE_ACCESS_READ:
      amode = R_OK;
      break;

    default:
      assert(!"Invalid flags argument");
  }
  *pResOut = (osAccess(zPath, amode)==0);
  if( flags==SQLITE_ACCESS_EXISTS && *pResOut ){
    struct stat buf;
    if( 0==stat(zPath, &buf) && buf.st_size==0 ){
      *pResOut = 0;
    }
  }
  return SQLITE_OK;
................................................................................
  UNUSED_PARAMETER(pVfs);

  zOut[nOut-1] = '\0';
  if( zPath[0]=='/' ){
    sqlite3_snprintf(nOut, zOut, "%s", zPath);
  }else{
    int nCwd;
    if( osGetcwd(zOut, nOut-1)==0 ){
      return unixLogError(SQLITE_CANTOPEN_BKPT, "getcwd", zPath);
    }
    nCwd = (int)strlen(zOut);
    sqlite3_snprintf(nOut-nCwd, &zOut[nCwd], "/%s", zPath);
  }
  return SQLITE_OK;
}

................................................................................
  ** that we always use the same random number sequence.  This makes the
  ** tests repeatable.
  */
  memset(zBuf, 0, nBuf);
#if !defined(SQLITE_TEST)
  {
    int pid, fd;
    fd = robust_open("/dev/urandom", O_RDONLY, 0);
    if( fd<0 ){
      time_t t;
      time(&t);
      memcpy(zBuf, &t, sizeof(t));
      pid = getpid();
      memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
      assert( sizeof(t)+sizeof(pid)<=(size_t)nBuf );
      nBuf = sizeof(t) + sizeof(pid);
    }else{
      do{ nBuf = osRead(fd, zBuf, nBuf); }while( nBuf<0 && errno==EINTR );
      robust_close(0, fd, __LINE__);
    }
  }
#endif
  return nBuf;
}


................................................................................
  }else{
    pUnused = sqlite3_malloc(sizeof(*pUnused));
    if( !pUnused ){
      return SQLITE_NOMEM;
    }
  }
  if( fd<0 ){
    fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
    terrno = errno;
    if( fd<0 && errno==ENOENT && islockfile ){
      if( proxyCreateLockPath(path) == SQLITE_OK ){
        fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
      }
    }
  }
  if( fd<0 ){
    openFlags = O_RDONLY;
    fd = robust_open(path, openFlags, SQLITE_DEFAULT_FILE_PERMISSIONS);
    terrno = errno;
  }
  if( fd<0 ){
    if( islockfile ){
      return SQLITE_BUSY;
    }
    switch (terrno) {
................................................................................
  pNew = (unixFile *)sqlite3_malloc(sizeof(*pNew));
  if( pNew==NULL ){
    rc = SQLITE_NOMEM;
    goto end_create_proxy;
  }
  memset(pNew, 0, sizeof(unixFile));
  pNew->openFlags = openFlags;
  memset(&dummyVfs, 0, sizeof(dummyVfs));
  dummyVfs.pAppData = (void*)&autolockIoFinder;
  dummyVfs.zName = "dummy";
  pUnused->fd = fd;
  pUnused->flags = openFlags;
  pNew->pUnused = pUnused;
  
  rc = fillInUnixFile(&dummyVfs, fd, dirfd, (sqlite3_file*)pNew, path, 0, 0, 0);
  if( rc==SQLITE_OK ){
    *ppFile = pNew;
    return SQLITE_OK;
  }
end_create_proxy:    
  robust_close(pNew, fd, __LINE__);
  sqlite3_free(pNew);
  sqlite3_free(pUnused);
  return rc;
}

#ifdef SQLITE_TEST
/* simulate multiple hosts by creating unique hostid file paths */
................................................................................
  pathLen = strlcpy(tPath, cPath, MAXPATHLEN);
  if( pathLen>MAXPATHLEN || pathLen<6 || 
     (strlcpy(&tPath[pathLen-5], "break", 6) != 5) ){
    sqlite3_snprintf(sizeof(errmsg),errmsg,"path error (len %d)",(int)pathLen);
    goto end_breaklock;
  }
  /* read the conch content */
  readLen = osPread(conchFile->h, buf, PROXY_MAXCONCHLEN, 0);
  if( readLen<PROXY_PATHINDEX ){
    sqlite3_snprintf(sizeof(errmsg),errmsg,"read error (len %d)",(int)readLen);
    goto end_breaklock;
  }
  /* write it out to the temporary break file */
  fd = robust_open(tPath, (O_RDWR|O_CREAT|O_EXCL),
                   SQLITE_DEFAULT_FILE_PERMISSIONS);
  if( fd<0 ){
    sqlite3_snprintf(sizeof(errmsg), errmsg, "create failed (%d)", errno);
    goto end_breaklock;
  }
  if( osPwrite(fd, buf, readLen, 0) != (ssize_t)readLen ){
    sqlite3_snprintf(sizeof(errmsg), errmsg, "write failed (%d)", errno);
    goto end_breaklock;
  }
  if( rename(tPath, cPath) ){
    sqlite3_snprintf(sizeof(errmsg), errmsg, "rename failed (%d)", errno);
    goto end_breaklock;
  }
  rc = 0;
  fprintf(stderr, "broke stale lock on %s\n", cPath);
  robust_close(pFile, conchFile->h, __LINE__);
  conchFile->h = fd;
  conchFile->openFlags = O_RDWR | O_CREAT;

end_breaklock:
  if( rc ){
    if( fd>=0 ){
      unlink(tPath);
      robust_close(pFile, fd, __LINE__);
    }
    fprintf(stderr, "failed to break stale lock on %s, %s\n", cPath, errmsg);
  }
  return rc;
}

/* Take the requested lock on the conch file and break a stale lock if the 
................................................................................
      /* If the lock failed (busy):
       * 1st try: get the mod time of the conch, wait 0.5s and try again. 
       * 2nd try: fail if the mod time changed or host id is different, wait 
       *           10 sec and try again
       * 3rd try: break the lock unless the mod time has changed.
       */
      struct stat buf;
      if( osFstat(conchFile->h, &buf) ){
        pFile->lastErrno = errno;
        return SQLITE_IOERR_LOCK;
      }
      
      if( nTries==1 ){
        conchModTime = buf.st_mtimespec;
        usleep(500000); /* wait 0.5 sec and try the lock again*/
................................................................................
      if( conchModTime.tv_sec != buf.st_mtimespec.tv_sec || 
         conchModTime.tv_nsec != buf.st_mtimespec.tv_nsec ){
        return SQLITE_BUSY;
      }
      
      if( nTries==2 ){  
        char tBuf[PROXY_MAXCONCHLEN];
        int len = osPread(conchFile->h, tBuf, PROXY_MAXCONCHLEN, 0);
        if( len<0 ){
          pFile->lastErrno = errno;
          return SQLITE_IOERR_LOCK;
        }
        if( len>PROXY_PATHINDEX && tBuf[0]==(char)PROXY_CONCHVERSION){
          /* don't break the lock if the host id doesn't match */
          if( 0!=memcmp(&tBuf[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN) ){
................................................................................
        memcpy(&writeBuffer[PROXY_HEADERLEN], myHostID, PROXY_HOSTIDLEN);
        if( pCtx->lockProxyPath!=NULL ){
          strlcpy(&writeBuffer[PROXY_PATHINDEX], pCtx->lockProxyPath, MAXPATHLEN);
        }else{
          strlcpy(&writeBuffer[PROXY_PATHINDEX], tempLockPath, MAXPATHLEN);
        }
        writeSize = PROXY_PATHINDEX + strlen(&writeBuffer[PROXY_PATHINDEX]);
        robust_ftruncate(conchFile->h, writeSize);
        rc = unixWrite((sqlite3_file *)conchFile, writeBuffer, writeSize, 0);
        fsync(conchFile->h);
        /* If we created a new conch file (not just updated the contents of a 
         ** valid conch file), try to match the permissions of the database 
         */
        if( rc==SQLITE_OK && createConch ){
          struct stat buf;
          int err = osFstat(pFile->h, &buf);
          if( err==0 ){
            mode_t cmode = buf.st_mode&(S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP |
                                        S_IROTH|S_IWOTH);
            /* try to match the database file R/W permissions, ignore failure */
#ifndef SQLITE_PROXY_DEBUG
            osFchmod(conchFile->h, cmode);
#else
            do{
              rc = osFchmod(conchFile->h, cmode);
            }while( rc==(-1) && errno==EINTR );
            if( rc!=0 ){
              int code = errno;
              fprintf(stderr, "fchmod %o FAILED with %d %s\n",
                      cmode, code, strerror(code));
            } else {
              fprintf(stderr, "fchmod %o SUCCEDED\n",cmode);
            }
          }else{
................................................................................
      }
      conchFile->pMethod->xUnlock((sqlite3_file*)conchFile, SHARED_LOCK);
      
    end_takeconch:
      OSTRACE(("TRANSPROXY: CLOSE  %d\n", pFile->h));
      if( rc==SQLITE_OK && pFile->openFlags ){
        if( pFile->h>=0 ){
          robust_close(pFile, pFile->h, __LINE__);



        }




        pFile->h = -1;
        int fd = robust_open(pCtx->dbPath, pFile->openFlags,
                      SQLITE_DEFAULT_FILE_PERMISSIONS);
        OSTRACE(("TRANSPROXY: OPEN  %d\n", fd));
        if( fd>=0 ){
          pFile->h = fd;
        }else{
          rc=SQLITE_CANTOPEN_BKPT; /* SQLITE_BUSY? proxyTakeConch called
           during locking */
................................................................................
      ** Ugh, since O_RDONLY==0x0000 we test for !O_RDWR since unixOpen asserts
      ** that openFlags will have only one of O_RDONLY or O_RDWR.
      */
      struct statfs fsInfo;
      struct stat conchInfo;
      int goLockless = 0;

      if( osStat(pCtx->conchFilePath, &conchInfo) == -1 ) {
        int err = errno;
        if( (err==ENOENT) && (statfs(dbPath, &fsInfo) != -1) ){
          goLockless = (fsInfo.f_flags&MNT_RDONLY) == MNT_RDONLY;
        }
      }
      if( goLockless ){
        pCtx->conchHeld = -1; /* read only FS/ lockless */
................................................................................
  ** Most finders simply return a pointer to a fixed sqlite3_io_methods
  ** object.  But the "autolockIoFinder" available on MacOSX does a little
  ** more than that; it looks at the filesystem type that hosts the 
  ** database file and tries to choose an locking method appropriate for
  ** that filesystem time.
  */
  #define UNIXVFS(VFSNAME, FINDER) {                        \
    3,                    /* iVersion */                    \
    sizeof(unixFile),     /* szOsFile */                    \
    MAX_PATHNAME,         /* mxPathname */                  \
    0,                    /* pNext */                       \
    VFSNAME,              /* zName */                       \
    (void*)&FINDER,       /* pAppData */                    \
    unixOpen,             /* xOpen */                       \
    unixDelete,           /* xDelete */                     \
................................................................................
    unixDlSym,            /* xDlSym */                      \
    unixDlClose,          /* xDlClose */                    \
    unixRandomness,       /* xRandomness */                 \
    unixSleep,            /* xSleep */                      \
    unixCurrentTime,      /* xCurrentTime */                \
    unixGetLastError,     /* xGetLastError */               \
    unixCurrentTimeInt64, /* xCurrentTimeInt64 */           \
    unixSetSystemCall,    /* xSetSystemCall */              \
    unixGetSystemCall,    /* xGetSystemCall */              \
    unixNextSystemCall,   /* xNextSystemCall */             \
  }

  /*
  ** All default VFSes for unix are contained in the following array.
  **
  ** Note that the sqlite3_vfs.pNext field of the VFS object is modified
  ** by the SQLite core when the VFS is registered.  So the following
................................................................................
#if SQLITE_ENABLE_LOCKING_STYLE && (OS_VXWORKS || defined(__APPLE__))
    UNIXVFS("unix",          autolockIoFinder ),
#else
    UNIXVFS("unix",          posixIoFinder ),
#endif
    UNIXVFS("unix-none",     nolockIoFinder ),
    UNIXVFS("unix-dotfile",  dotlockIoFinder ),
    UNIXVFS("unix-excl",     posixIoFinder ),
#if OS_VXWORKS
    UNIXVFS("unix-namedsem", semIoFinder ),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
    UNIXVFS("unix-posix",    posixIoFinder ),
#if !OS_VXWORKS
    UNIXVFS("unix-flock",    flockIoFinder ),
................................................................................


/*
** Initialize and deinitialize the operating system interface.
*/
SQLITE_API int sqlite3_os_init(void){
  static sqlite3_vfs winVfs = {
    3,                   /* iVersion */
    sizeof(winFile),     /* szOsFile */
    MAX_PATH,            /* mxPathname */
    0,                   /* pNext */
    "win32",             /* zName */
    0,                   /* pAppData */
    winOpen,             /* xOpen */
    winDelete,           /* xDelete */
................................................................................
    winDlSym,            /* xDlSym */
    winDlClose,          /* xDlClose */
    winRandomness,       /* xRandomness */
    winSleep,            /* xSleep */
    winCurrentTime,      /* xCurrentTime */
    winGetLastError,     /* xGetLastError */
    winCurrentTimeInt64, /* xCurrentTimeInt64 */
    0,                   /* xSetSystemCall */
    0,                   /* xGetSystemCall */
    0,                   /* xNextSystemCall */
  };

#ifndef SQLITE_OMIT_WAL
  /* get memory map allocation granularity */
  memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
  GetSystemInfo(&winSysInfo);
  assert(winSysInfo.dwAllocationGranularity > 0);
................................................................................
*/

#ifndef _WAL_H_
#define _WAL_H_


#ifdef SQLITE_OMIT_WAL
# define sqlite3WalOpen(x,y,z)                   0
# define sqlite3WalClose(w,x,y,z)                0
# define sqlite3WalBeginReadTransaction(y,z)     0
# define sqlite3WalEndReadTransaction(z)
# define sqlite3WalRead(v,w,x,y,z)               0
# define sqlite3WalDbsize(y)                     0
# define sqlite3WalBeginWriteTransaction(y)      0
# define sqlite3WalEndWriteTransaction(x)        0
# define sqlite3WalUndo(x,y,z)                   0
# define sqlite3WalSavepoint(y,z)
# define sqlite3WalSavepointUndo(y,z)            0
# define sqlite3WalFrames(u,v,w,x,y,z)           0
# define sqlite3WalCheckpoint(r,s,t,u,v,w,x,y,z) 0
# define sqlite3WalCallback(z)                   0
# define sqlite3WalExclusiveMode(y,z)            0
# define sqlite3WalHeapMemory(z)                 0
#else

#define WAL_SAVEPOINT_NDATA 4

/* Connection to a write-ahead log (WAL) file. 
** There is one object of this type for each pager. 
*/
................................................................................

/* Write a frame or frames to the log. */
SQLITE_PRIVATE int sqlite3WalFrames(Wal *pWal, int, PgHdr *, Pgno, int, int);

/* Copy pages from the log to the database file */ 
SQLITE_PRIVATE int sqlite3WalCheckpoint(
  Wal *pWal,                      /* Write-ahead log connection */
  int eMode,                      /* One of PASSIVE, FULL and RESTART */
  int (*xBusy)(void*),            /* Function to call when busy */
  void *pBusyArg,                 /* Context argument for xBusyHandler */
  int sync_flags,                 /* Flags to sync db file with (or 0) */
  int nBuf,                       /* Size of buffer nBuf */
  u8 *zBuf,                       /* Temporary buffer to use */
  int *pnLog,                     /* OUT: Number of frames in WAL */
  int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
);

/* Return the value to pass to a sqlite3_wal_hook callback, the
** number of frames in the WAL at the point of the last commit since
** sqlite3WalCallback() was called.  If no commits have occurred since
** the last call, then return 0.
*/
................................................................................
  PAGER_INCR(pPager->nRead);
  IOTRACE(("PGIN %p %d\n", pPager, pgno));
  PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
               PAGERID(pPager), pgno, pager_pagehash(pPg)));

  return rc;
}

/*
** Update the value of the change-counter at offsets 24 and 92 in
** the header and the sqlite version number at offset 96.
**
** This is an unconditional update.  See also the pager_incr_changecounter()
** routine which only updates the change-counter if the update is actually
** needed, as determined by the pPager->changeCountDone state variable.
*/
static void pager_write_changecounter(PgHdr *pPg){
  u32 change_counter;

  /* Increment the value just read and write it back to byte 24. */
  change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
  put32bits(((char*)pPg->pData)+24, change_counter);

  /* Also store the SQLite version number in bytes 96..99 and in
  ** bytes 92..95 store the change counter for which the version number
  ** is valid. */
  put32bits(((char*)pPg->pData)+92, change_counter);
  put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
}

#ifndef SQLITE_OMIT_WAL
/*
** This function is invoked once for each page that has already been 
** written into the log file when a WAL transaction is rolled back.
** Parameter iPg is the page number of said page. The pCtx argument 
** is actually a pointer to the Pager structure.
................................................................................
    rc = pagerUndoCallback((void *)pPager, pList->pgno);
    pList = pNext;
  }

  return rc;
}
























/*
** This function is a wrapper around sqlite3WalFrames(). As well as logging
** the contents of the list of pages headed by pList (connected by pDirty),
** this function notifies any active backup processes that the pages have
** changed. 
**
** The list of pages passed into this routine is always sorted by page number.
** Hence, if page 1 appears anywhere on the list, it will be the first page.
*/ 
static int pagerWalFrames(
  Pager *pPager,                  /* Pager object */
  PgHdr *pList,                   /* List of frames to log */
................................................................................
  assert( pPager->pWal );
#ifdef SQLITE_DEBUG
  /* Verify that the page list is in accending order */
  for(p=pList; p && p->pDirty; p=p->pDirty){
    assert( p->pgno < p->pDirty->pgno );
  }
#endif

  if( isCommit ){
    /* If a WAL transaction is being committed, there is no point in writing
    ** any pages with page numbers greater than nTruncate into the WAL file.
    ** They will never be read by any client. So remove them from the pDirty
    ** list here. */
    PgHdr *p;
    PgHdr **ppNext = &pList;
    for(p=pList; (*ppNext = p); p=p->pDirty){
      if( p->pgno<=nTruncate ) ppNext = &p->pDirty;
    }
    assert( pList );
  }

  if( pList->pgno==1 ) pager_write_changecounter(pList);
  rc = sqlite3WalFrames(pPager->pWal, 
      pPager->pageSize, pList, nTruncate, isCommit, syncFlags
  );
  if( rc==SQLITE_OK && pPager->pBackup ){
    PgHdr *p;
    for(p=pList; p; p=p->pDirty){
      sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
    }
  }

#ifdef SQLITE_CHECK_PAGES
  pList = sqlite3PcacheDirtyList(pPager->pPCache);
  for(p=pList; p; p=p->pDirty){
    pager_set_pagehash(p);
  }
#endif

  return rc;
}
................................................................................
*/
SQLITE_PRIVATE sqlite3_backup **sqlite3PagerBackupPtr(Pager *pPager){
  return &pPager->pBackup;
}

#ifndef SQLITE_OMIT_WAL
/*
** This function is called when the user invokes "PRAGMA wal_checkpoint",
** "PRAGMA wal_blocking_checkpoint" or calls the sqlite3_wal_checkpoint()
** or wal_blocking_checkpoint() API functions.
**
** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
*/
SQLITE_PRIVATE int sqlite3PagerCheckpoint(Pager *pPager, int eMode, int *pnLog, int *pnCkpt){
  int rc = SQLITE_OK;
  if( pPager->pWal ){

    rc = sqlite3WalCheckpoint(pPager->pWal, eMode,

        pPager->xBusyHandler, pPager->pBusyHandlerArg,
        pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
        pnLog, pnCkpt
    );
  }
  return rc;
}

SQLITE_PRIVATE int sqlite3PagerWalCallback(Pager *pPager){
  return sqlite3WalCallback(pPager->pWal);
}
................................................................................
*/
static int pagerExclusiveLock(Pager *pPager){
  int rc;                         /* Return code */

  assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
  rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
  if( rc!=SQLITE_OK ){
    /* If the attempt to grab the exclusive lock failed, release the 
    ** pending lock that may have been obtained instead.  */
    pagerUnlockDb(pPager, SHARED_LOCK);
  }

  return rc;
}

/*
................................................................................

  if( rc!=SQLITE_OK ){
    walIteratorFree(p);
  }
  *pp = p;
  return rc;
}

/*
** Attempt to obtain the exclusive WAL lock defined by parameters lockIdx and
** n. If the attempt fails and parameter xBusy is not NULL, then it is a
** busy-handler function. Invoke it and retry the lock until either the
** lock is successfully obtained or the busy-handler returns 0.
*/
static int walBusyLock(
  Wal *pWal,                      /* WAL connection */
  int (*xBusy)(void*),            /* Function to call when busy */
  void *pBusyArg,                 /* Context argument for xBusyHandler */
  int lockIdx,                    /* Offset of first byte to lock */
  int n                           /* Number of bytes to lock */
){
  int rc;
  do {
    rc = walLockExclusive(pWal, lockIdx, n);
  }while( xBusy && rc==SQLITE_BUSY && xBusy(pBusyArg) );
  return rc;
}

/*
** The cache of the wal-index header must be valid to call this function.
** Return the page-size in bytes used by the database.
*/
static int walPagesize(Wal *pWal){
  return (pWal->hdr.szPage&0xfe00) + ((pWal->hdr.szPage&0x0001)<<16);
}

/*
** Copy as much content as we can from the WAL back into the database file
** in response to an sqlite3_wal_checkpoint() request or the equivalent.
**
** The amount of information copies from WAL to database might be limited
** by active readers.  This routine will never overwrite a database page
................................................................................
**
** The caller must be holding sufficient locks to ensure that no other
** checkpoint is running (in any other thread or process) at the same
** time.
*/
static int walCheckpoint(
  Wal *pWal,                      /* Wal connection */
  int eMode,                      /* One of PASSIVE, FULL or RESTART */
  int (*xBusyCall)(void*),        /* Function to call when busy */
  void *pBusyArg,                 /* Context argument for xBusyHandler */
  int sync_flags,                 /* Flags for OsSync() (or 0) */

  u8 *zBuf                        /* Temporary buffer to use */
){
  int rc;                         /* Return code */
  int szPage;                     /* Database page-size */
  WalIterator *pIter = 0;         /* Wal iterator context */
  u32 iDbpage = 0;                /* Next database page to write */
  u32 iFrame = 0;                 /* Wal frame containing data for iDbpage */
  u32 mxSafeFrame;                /* Max frame that can be backfilled */
  u32 mxPage;                     /* Max database page to write */
  int i;                          /* Loop counter */
  volatile WalCkptInfo *pInfo;    /* The checkpoint status information */
  int (*xBusy)(void*) = 0;        /* Function to call when waiting for locks */


  szPage = walPagesize(pWal);
  testcase( szPage<=32768 );
  testcase( szPage>=65536 );
  pInfo = walCkptInfo(pWal);
  if( pInfo->nBackfill>=pWal->hdr.mxFrame ) return SQLITE_OK;

  /* Allocate the iterator */
  rc = walIteratorInit(pWal, &pIter);
  if( rc!=SQLITE_OK ){
    return rc;
  }
  assert( pIter );

  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ) xBusy = xBusyCall;





  /* Compute in mxSafeFrame the index of the last frame of the WAL that is
  ** safe to write into the database.  Frames beyond mxSafeFrame might
  ** overwrite database pages that are in use by active readers and thus
  ** cannot be backfilled from the WAL.
  */
  mxSafeFrame = pWal->hdr.mxFrame;
  mxPage = pWal->hdr.nPage;
  for(i=1; i<WAL_NREADER; i++){
    u32 y = pInfo->aReadMark[i];
    if( mxSafeFrame>y ){
      assert( y<=pWal->hdr.mxFrame );
      rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
      if( rc==SQLITE_OK ){
        pInfo->aReadMark[i] = READMARK_NOT_USED;
        walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
      }else if( rc==SQLITE_BUSY ){
        mxSafeFrame = y;
        xBusy = 0;
      }else{
        goto walcheckpoint_out;
      }
    }
  }

  if( pInfo->nBackfill<mxSafeFrame
   && (rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(0), 1))==SQLITE_OK
  ){
    i64 nSize;                    /* Current size of database file */
    u32 nBackfill = pInfo->nBackfill;

    /* Sync the WAL to disk */
    if( sync_flags ){
      rc = sqlite3OsSync(pWal->pWalFd, sync_flags);
................................................................................
      if( rc==SQLITE_OK ){
        pInfo->nBackfill = mxSafeFrame;
      }
    }

    /* Release the reader lock held while backfilling */
    walUnlockExclusive(pWal, WAL_READ_LOCK(0), 1);
  }

  if( rc==SQLITE_BUSY ){
    /* Reset the return code so as not to report a checkpoint failure

    ** just because there are active readers.  */
    rc = SQLITE_OK;
  }

  /* If this is an SQLITE_CHECKPOINT_RESTART operation, and the entire wal
  ** file has been copied into the database file, then block until all
  ** readers have finished using the wal file. This ensures that the next
  ** process to write to the database restarts the wal file.
  */
  if( rc==SQLITE_OK && eMode!=SQLITE_CHECKPOINT_PASSIVE ){
    assert( pWal->writeLock );
    if( pInfo->nBackfill<pWal->hdr.mxFrame ){
      rc = SQLITE_BUSY;
    }else if( eMode==SQLITE_CHECKPOINT_RESTART ){
      assert( mxSafeFrame==pWal->hdr.mxFrame );
      rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(1), WAL_NREADER-1);
      if( rc==SQLITE_OK ){
        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
      }
    }
  }

 walcheckpoint_out:
  walIteratorFree(pIter);
  return rc;
}

/*
................................................................................
    ** The EXCLUSIVE lock is not released before returning.
    */
    rc = sqlite3OsLock(pWal->pDbFd, SQLITE_LOCK_EXCLUSIVE);
    if( rc==SQLITE_OK ){
      if( pWal->exclusiveMode==WAL_NORMAL_MODE ){
        pWal->exclusiveMode = WAL_EXCLUSIVE_MODE;
      }
      rc = sqlite3WalCheckpoint(
          pWal, SQLITE_CHECKPOINT_PASSIVE, 0, 0, sync_flags, nBuf, zBuf, 0, 0
      );
      if( rc==SQLITE_OK ){
        isDelete = 1;
      }
    }

    walIndexClose(pWal, isDelete);
    sqlite3OsClose(pWal->pWalFd);
................................................................................
  u32 mxReadMark;                 /* Largest aReadMark[] value */
  int mxI;                        /* Index of largest aReadMark[] value */
  int i;                          /* Loop counter */
  int rc = SQLITE_OK;             /* Return code  */

  assert( pWal->readLock<0 );     /* Not currently locked */

  /* Take steps to avoid spinning forever if there is a protocol error.
  **
  ** Circumstances that cause a RETRY should only last for the briefest
  ** instances of time.  No I/O or other system calls are done while the
  ** locks are held, so the locks should not be held for very long. But 
  ** if we are unlucky, another process that is holding a lock might get
  ** paged out or take a page-fault that is time-consuming to resolve, 
  ** during the few nanoseconds that it is holding the lock.  In that case,
  ** it might take longer than normal for the lock to free.
  **
  ** After 5 RETRYs, we begin calling sqlite3OsSleep().  The first few
  ** calls to sqlite3OsSleep() have a delay of 1 microsecond.  Really this
  ** is more of a scheduler yield than an actual delay.  But on the 10th
  ** an subsequent retries, the delays start becoming longer and longer, 
  ** so that on the 100th (and last) RETRY we delay for 21 milliseconds.
  ** The total delay time before giving up is less than 1 second.
  */
  if( cnt>5 ){
    int nDelay = 1;                      /* Pause time in microseconds */
    if( cnt>100 ){
      VVA_ONLY( pWal->lockError = 1; )
      return SQLITE_PROTOCOL;
    }
    if( cnt>=10 ) nDelay = (cnt-9)*238;  /* Max delay 21ms. Total delay 996ms */
    sqlite3OsSleep(pWal->pVfs, nDelay);
  }

  if( !useWal ){
    rc = walIndexReadHdr(pWal, pChanged);
    if( rc==SQLITE_BUSY ){
      /* If there is not a recovery running in another thread or process
      ** then convert BUSY errors to WAL_RETRY.  If recovery is known to
................................................................................
    u32 thisMark = pInfo->aReadMark[i];
    if( mxReadMark<=thisMark && thisMark<=pWal->hdr.mxFrame ){
      assert( thisMark!=READMARK_NOT_USED );
      mxReadMark = thisMark;
      mxI = i;
    }
  }
  /* There was once an "if" here. The extra "{" is to preserve indentation. */














  {
    if( mxReadMark < pWal->hdr.mxFrame || mxI==0 ){
      for(i=1; i<WAL_NREADER; i++){
        rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
        if( rc==SQLITE_OK ){
          mxReadMark = pInfo->aReadMark[i] = pWal->hdr.mxFrame;
          mxI = i;
          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
          break;
        }else if( rc!=SQLITE_BUSY ){
          return rc;
        }
      }
    }
    if( mxI==0 ){
      assert( rc==SQLITE_BUSY );
      return WAL_RETRY;
    }

    rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
    if( rc ){
      return rc==SQLITE_BUSY ? WAL_RETRY : rc;
    }
    /* Now that the read-lock has been obtained, check that neither the
    ** value in the aReadMark[] array or the contents of the wal-index
................................................................................
SQLITE_PRIVATE int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
  int rc;                         /* Return code */
  int cnt = 0;                    /* Number of TryBeginRead attempts */

  do{
    rc = walTryBeginRead(pWal, pChanged, 0, ++cnt);
  }while( rc==WAL_RETRY );
  testcase( (rc&0xff)==SQLITE_BUSY );
  testcase( (rc&0xff)==SQLITE_IOERR );
  testcase( rc==SQLITE_PROTOCOL );
  testcase( rc==SQLITE_OK );
  return rc;
}

/*
** Finish with a read transaction.  All this does is release the
** read-lock.
*/
................................................................................
  int rc = SQLITE_OK;
  int cnt;

  if( pWal->readLock==0 ){
    volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
    assert( pInfo->nBackfill==pWal->hdr.mxFrame );
    if( pInfo->nBackfill>0 ){
      u32 salt1;
      sqlite3_randomness(4, &salt1);
      rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
      if( rc==SQLITE_OK ){
        /* If all readers are using WAL_READ_LOCK(0) (in other words if no
        ** readers are currently using the WAL), then the transactions
        ** frames will overwrite the start of the existing log. Update the
        ** wal-index header to reflect this.
        **
................................................................................
        ** to handle if this transaction is rolled back.
        */
        int i;                    /* Loop counter */
        u32 *aSalt = pWal->hdr.aSalt;       /* Big-endian salt values */
        pWal->nCkpt++;
        pWal->hdr.mxFrame = 0;
        sqlite3Put4byte((u8*)&aSalt[0], 1 + sqlite3Get4byte((u8*)&aSalt[0]));
        aSalt[1] = salt1;
        walIndexWriteHdr(pWal);
        pInfo->nBackfill = 0;
        for(i=1; i<WAL_NREADER; i++) pInfo->aReadMark[i] = READMARK_NOT_USED;
        assert( pInfo->aReadMark[0]==0 );
        walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
      }else if( rc!=SQLITE_BUSY ){
        return rc;
................................................................................
    walUnlockShared(pWal, WAL_READ_LOCK(0));
    pWal->readLock = -1;
    cnt = 0;
    do{
      int notUsed;
      rc = walTryBeginRead(pWal, &notUsed, 1, ++cnt);
    }while( rc==WAL_RETRY );
    assert( (rc&0xff)!=SQLITE_BUSY ); /* BUSY not possible when useWal==1 */
    testcase( (rc&0xff)==SQLITE_IOERR );
    testcase( rc==SQLITE_PROTOCOL );
    testcase( rc==SQLITE_OK );
  }
  return rc;
}

/* 
** Write a set of frames to the log. The caller must hold the write-lock
** on the log file (obtained using sqlite3WalBeginWriteTransaction()).
................................................................................

/* 
** This routine is called to implement sqlite3_wal_checkpoint() and
** related interfaces.
**
** Obtain a CHECKPOINT lock and then backfill as much information as
** we can from WAL into the database.
**
** If parameter xBusy is not NULL, it is a pointer to a busy-handler
** callback. In this case this function runs a blocking checkpoint.
*/
SQLITE_PRIVATE int sqlite3WalCheckpoint(
  Wal *pWal,                      /* Wal connection */
  int eMode,                      /* PASSIVE, FULL or RESTART */
  int (*xBusy)(void*),            /* Function to call when busy */
  void *pBusyArg,                 /* Context argument for xBusyHandler */
  int sync_flags,                 /* Flags to sync db file with (or 0) */
  int nBuf,                       /* Size of temporary buffer */
  u8 *zBuf,                       /* Temporary buffer to use */
  int *pnLog,                     /* OUT: Number of frames in WAL */
  int *pnCkpt                     /* OUT: Number of backfilled frames in WAL */
){
  int rc;                         /* Return code */
  int isChanged = 0;              /* True if a new wal-index header is loaded */
  int eMode2 = eMode;             /* Mode to pass to walCheckpoint() */

  assert( pWal->ckptLock==0 );
  assert( pWal->writeLock==0 );

  WALTRACE(("WAL%p: checkpoint begins\n", pWal));
  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
  if( rc ){
    /* Usually this is SQLITE_BUSY meaning that another thread or process
    ** is already running a checkpoint, or maybe a recovery.  But it might
    ** also be SQLITE_IOERR. */
    return rc;
  }
  pWal->ckptLock = 1;

  /* If this is a blocking-checkpoint, then obtain the write-lock as well
  ** to prevent any writers from running while the checkpoint is underway.
  ** This has to be done before the call to walIndexReadHdr() below.
  **
  ** If the writer lock cannot be obtained, then a passive checkpoint is
  ** run instead. Since the checkpointer is not holding the writer lock,
  ** there is no point in blocking waiting for any readers. Assuming no 
  ** other error occurs, this function will return SQLITE_BUSY to the caller.
  */
  if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
    rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
    if( rc==SQLITE_OK ){
      pWal->writeLock = 1;
    }else if( rc==SQLITE_BUSY ){
      eMode2 = SQLITE_CHECKPOINT_PASSIVE;
      rc = SQLITE_OK;
    }
  }

  /* Read the wal-index header. */
  if( rc==SQLITE_OK ){
    rc = walIndexReadHdr(pWal, &isChanged);
  }

  /* Copy data from the log to the database file. */
  if( rc==SQLITE_OK ){
    if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
      rc = SQLITE_CORRUPT_BKPT;
    }else{
      rc = walCheckpoint(pWal, eMode2, xBusy, pBusyArg, sync_flags, zBuf);
    }

    /* If no error occurred, set the output variables. */
    if( rc==SQLITE_OK || rc==SQLITE_BUSY ){
      if( pnLog ) *pnLog = (int)pWal->hdr.mxFrame;
      if( pnCkpt ) *pnCkpt = (int)(walCkptInfo(pWal)->nBackfill);
    }
  }

  if( isChanged ){
    /* If a new wal-index header was loaded before the checkpoint was 
    ** performed, then the pager-cache associated with pWal is now
    ** out of date. So zero the cached wal-index header to ensure that
    ** next time the pager opens a snapshot on this database it knows that
    ** the cache needs to be reset.
    */
    memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
  }

  /* Release the locks. */
  sqlite3WalEndWriteTransaction(pWal);
  walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
  pWal->ckptLock = 0;
  WALTRACE(("WAL%p: checkpoint %s\n", pWal, rc ? "failed" : "ok"));
  return (rc==SQLITE_OK && eMode!=eMode2 ? SQLITE_BUSY : rc);
}

/* Return the value to pass to a sqlite3_wal_hook callback, the
** number of frames in the WAL at the point of the last commit since
** sqlite3WalCallback() was called.  If no commits have occurred since
** the last call, then return 0.
*/
................................................................................
**      *     zero or more pages numbers of leaves
*/


/* The following value is the maximum cell size assuming a maximum page
** size give above.
*/
#define MX_CELL_SIZE(pBt)  ((int)(pBt->pageSize-8))

/* The maximum number of cells on a single page of the database.  This
** assumes a minimum cell size of 6 bytes  (4 bytes for the cell itself
** plus 2 bytes for the index to the cell in the page header).  Such
** small cells will be rare, but they are possible.
*/
#define MX_CELL(pBt) ((pBt->pageSize-8)/6)
................................................................................
** points to the same BtShared object.  The database cache and the
** schema associated with the database file are all contained within
** the BtShared object.
**
** All fields in this structure are accessed under sqlite3.mutex.
** The pBt pointer itself may not be changed while there exists cursors 
** in the referenced BtShared that point back to this Btree since those
** cursors have to go through this Btree to find their BtShared and
** they often do so without holding sqlite3.mutex.
*/
struct Btree {
  sqlite3 *db;       /* The database connection holding this btree */
  BtShared *pBt;     /* Sharable content of this btree */
  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
  u8 sharable;       /* True if we can share pBt with another db */
................................................................................
  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */
  u32 pageSize;         /* Total number of bytes on a page */
  u32 usableSize;       /* Number of usable bytes on each page */
  int nTransaction;     /* Number of open transactions (read + write) */
  u32 nPage;            /* Number of pages in the database */
  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this object */
  Bitvec *pHasContent;  /* Set of pages moved to free-list this transaction */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nRef;             /* Number of references to this structure */
  BtShared *pNext;      /* Next on a list of sharable BtShared structs */
  BtLock *pLock;        /* List of locks held on this shared-btree struct */
  Btree *pWriter;       /* Btree with currently open write transaction */
  u8 isExclusive;       /* True if pWriter has an EXCLUSIVE lock on the db */
................................................................................
}

/*
** Release the BtShared mutex associated with B-Tree handle p and
** clear the p->locked boolean.
*/
static void unlockBtreeMutex(Btree *p){
  BtShared *pBt = p->pBt;
  assert( p->locked==1 );
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( sqlite3_mutex_held(p->db->mutex) );
  assert( p->db==pBt->db );

  sqlite3_mutex_leave(pBt->mutex);
  p->locked = 0;
}

/*
** Enter a mutex on the given BTree object.
**
** If the object is not sharable, then no mutex is ever required
................................................................................
** Enter the mutexes in accending order by BtShared pointer address
** to avoid the possibility of deadlock when two threads with
** two or more btrees in common both try to lock all their btrees
** at the same instant.
*/
SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
  int i;
  Btree *p;
  assert( sqlite3_mutex_held(db->mutex) );
  for(i=0; i<db->nDb; i++){
    p = db->aDb[i].pBt;
    if( p ) sqlite3BtreeEnter(p);



















  }
}
SQLITE_PRIVATE void sqlite3BtreeLeaveAll(sqlite3 *db){
  int i;
  Btree *p;
  assert( sqlite3_mutex_held(db->mutex) );
  for(i=0; i<db->nDb; i++){
    p = db->aDb[i].pBt;
    if( p ) sqlite3BtreeLeave(p);




  }
}

/*
** Return true if a particular Btree requires a lock.  Return FALSE if
** no lock is ever required since it is not sharable.
*/
SQLITE_PRIVATE int sqlite3BtreeSharable(Btree *p){
  return p->sharable;
}

#ifndef NDEBUG
/*
** Return true if the current thread holds the database connection
** mutex and all required BtShared mutexes.
**
** This routine is used inside assert() statements only.
................................................................................
      return 0;
    }
  }
  return 1;
}
#endif /* NDEBUG */

#ifndef NDEBUG
/*

** Return true if the correct mutexes are held for accessing the
** db->aDb[iDb].pSchema structure.  The mutexes required for schema
** access are:
**

**   (1) The mutex on db
**   (2) if iDb!=1, then the mutex on db->aDb[iDb].pBt.

**
** If pSchema is not NULL, then iDb is computed from pSchema and
** db using sqlite3SchemaToIndex().

*/
SQLITE_PRIVATE int sqlite3SchemaMutexHeld(sqlite3 *db, int iDb, Schema *pSchema){
  Btree *p;
  assert( db!=0 );
  if( pSchema ) iDb = sqlite3SchemaToIndex(db, pSchema);
  assert( iDb>=0 && iDb<db->nDb );
  if( !sqlite3_mutex_held(db->mutex) ) return 0;

  if( iDb==1 ) return 1;
  p = db->aDb[iDb].pBt;
  assert( p!=0 );
  return p->sharable==0 || p->locked==1;
}

#endif /* NDEBUG */

















#else /* SQLITE_THREADSAFE>0 above.  SQLITE_THREADSAFE==0 below */
/*



** The following are special cases for mutex enter routines for use
** in single threaded applications that use shared cache.  Except for
** these two routines, all mutex operations are no-ops in that case and
** are null #defines in btree.h.
**
























** If shared cache is disabled, then all btree mutex routines, including
** the ones below, are no-ops and are null #defines in btree.h.
*/




















SQLITE_PRIVATE void sqlite3BtreeEnter(Btree *p){
  p->pBt->db = p->db;
}
SQLITE_PRIVATE void sqlite3BtreeEnterAll(sqlite3 *db){
  int i;
  for(i=0; i<db->nDb; i++){
    Btree *p = db->aDb[i].pBt;
................................................................................
  ** and the cell content area.  The btreeInitPage() call has already
  ** validated the freelist.  Given that the freelist is valid, there
  ** is no way that the allocation can extend off the end of the page.
  ** The assert() below verifies the previous sentence.
  */
  top -= nByte;
  put2byte(&data[hdr+5], top);
  assert( top+nByte <= (int)pPage->pBt->usableSize );
  *pIdx = top;
  return SQLITE_OK;
}

/*
** Return a section of the pPage->aData to the freelist.
** The first byte of the new free block is pPage->aDisk[start]
................................................................................
  int addr, pbegin, hdr;
  int iLast;                        /* Largest possible freeblock offset */
  unsigned char *data = pPage->aData;

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( start>=pPage->hdrOffset+6+pPage->childPtrSize );
  assert( (start + size) <= (int)pPage->pBt->usableSize );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( size>=0 );   /* Minimum cell size is 4 */

  if( pPage->pBt->secureDelete ){
    /* Overwrite deleted information with zeros when the secure_delete
    ** option is enabled */
    memset(&data[start], 0, size);
................................................................................
  pPage->nFree = pPage->nFree + (u16)size;

  /* Coalesce adjacent free blocks */
  addr = hdr + 1;
  while( (pbegin = get2byte(&data[addr]))>0 ){
    int pnext, psize, x;
    assert( pbegin>addr );
    assert( pbegin <= (int)pPage->pBt->usableSize-4 );
    pnext = get2byte(&data[pbegin]);
    psize = get2byte(&data[pbegin+2]);
    if( pbegin + psize + 3 >= pnext && pnext>0 ){
      int frag = pnext - (pbegin+psize);
      if( (frag<0) || (frag>(int)data[hdr+7]) ){
        return SQLITE_CORRUPT_BKPT;
      }
................................................................................
  sqlite3BtreeEnter(p);
  assert( pBt && pBt->pPager );
  rc = sqlite3PagerNosync(pBt->pPager);
  sqlite3BtreeLeave(p);
  return rc;
}


/*
** Change the default pages size and the number of reserved bytes per page.
** Or, if the page size has already been fixed, return SQLITE_READONLY 
** without changing anything.
**
** The page size must be a power of 2 between 512 and 65536.  If the page
** size supplied does not meet this constraint then the page size is not
................................................................................
/*
** Return the currently defined page size
*/
SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree *p){
  return p->pBt->pageSize;
}

#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
/*
** Return the number of bytes of space at the end of every page that
** are intentually left unused.  This is the "reserved" space that is
** sometimes used by extensions.
*/
SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree *p){
  int n;
................................................................................
      pBt->usableSize = usableSize;
      pBt->pageSize = pageSize;
      freeTempSpace(pBt);
      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
                                   pageSize-usableSize);
      return rc;
    }
    if( (pBt->db->flags & SQLITE_RecoveryMode)==0 && nPage>nPageFile ){
      rc = SQLITE_CORRUPT_BKPT;
      goto page1_init_failed;
    }
    if( usableSize<480 ){
      goto page1_init_failed;
    }
    pBt->pageSize = pageSize;
................................................................................
** sqlite3BtreeCommitPhaseOne() routine does the first phase and should
** be invoked prior to calling this routine.  The sqlite3BtreeCommitPhaseOne()
** routine did all the work of writing information out to disk and flushing the
** contents so that they are written onto the disk platter.  All this
** routine has to do is delete or truncate or zero the header in the
** the rollback journal (which causes the transaction to commit) and
** drop locks.
**
** Normally, if an error occurs while the pager layer is attempting to 
** finalize the underlying journal file, this function returns an error and
** the upper layer will attempt a rollback. However, if the second argument
** is non-zero then this b-tree transaction is part of a multi-file 
** transaction. In this case, the transaction has already been committed 
** (by deleting a master journal file) and the caller will ignore this 
** functions return code. So, even if an error occurs in the pager layer,
** reset the b-tree objects internal state to indicate that the write
** transaction has been closed. This is quite safe, as the pager will have
** transitioned to the error state.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree *p, int bCleanup){

  if( p->inTrans==TRANS_NONE ) return SQLITE_OK;
  sqlite3BtreeEnter(p);
  btreeIntegrity(p);

  /* If the handle has a write-transaction open, commit the shared-btrees 
  ** transaction and set the shared state to TRANS_READ.
................................................................................
  */
  if( p->inTrans==TRANS_WRITE ){
    int rc;
    BtShared *pBt = p->pBt;
    assert( pBt->inTransaction==TRANS_WRITE );
    assert( pBt->nTransaction>0 );
    rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
    if( rc!=SQLITE_OK && bCleanup==0 ){
      sqlite3BtreeLeave(p);
      return rc;
    }
    pBt->inTransaction = TRANS_READ;
  }

  btreeEndTransaction(p);
................................................................................
** Do both phases of a commit.
*/
SQLITE_PRIVATE int sqlite3BtreeCommit(Btree *p){
  int rc;
  sqlite3BtreeEnter(p);
  rc = sqlite3BtreeCommitPhaseOne(p, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3BtreeCommitPhaseTwo(p, 0);
  }
  sqlite3BtreeLeave(p);
  return rc;
}

#ifndef NDEBUG
/*
................................................................................
        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }

      k = get4byte(&pTrunk->aData[4]); /* # of leaves on this trunk page */
      if( k==0 && !searchList ){
        /* The trunk has no leaves and the list is not being searched. 
        ** So extract the trunk page itself and use it as the newly 
        ** allocated page */
        assert( pPrevTrunk==0 );
        rc = sqlite3PagerWrite(pTrunk->pDbPage);
        if( rc ){
................................................................................
        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
#endif
      }else if( k>0 ){
        /* Extract a leaf from the trunk */
        u32 closest;
        Pgno iPage;
        unsigned char *aData = pTrunk->aData;




        if( nearby>0 ){
          u32 i;
          int dist;
          closest = 0;
          dist = sqlite3AbsInt32(get4byte(&aData[8]) - nearby);

          for(i=1; i<k; i++){
            int d2 = sqlite3AbsInt32(get4byte(&aData[8+i*4]) - nearby);

            if( d2<dist ){
              closest = i;
              dist = d2;
            }
          }
        }else{
          closest = 0;
................................................................................
        testcase( iPage==mxPage );
        if( !searchList || iPage==nearby ){
          int noContent;
          *pPgno = iPage;
          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
                 ": %d more free pages\n",
                 *pPgno, closest+1, k, pTrunk->pgno, n-1));
          rc = sqlite3PagerWrite(pTrunk->pDbPage);
          if( rc ) goto end_allocate_page;
          if( closest<k-1 ){
            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
          }
          put4byte(&aData[4], k-1);

          noContent = !btreeGetHasContent(pBt, *pPgno);
          rc = btreeGetPage(pBt, *pPgno, ppPage, noContent);
          if( rc==SQLITE_OK ){
            rc = sqlite3PagerWrite((*ppPage)->pDbPage);
            if( rc!=SQLITE_OK ){
              releasePage(*ppPage);
            }
................................................................................
      releasePage(*ppPage);
      return SQLITE_CORRUPT_BKPT;
    }
    (*ppPage)->isInit = 0;
  }else{
    *ppPage = 0;
  }
  assert( rc!=SQLITE_OK || sqlite3PagerIswriteable((*ppPage)->pDbPage) );
  return rc;
}

/*
** This function is used to add page iPage to the database file free-list. 
** It is assumed that the page is not already a part of the free-list.
**
................................................................................
    end = cellOffset + 2*pPage->nCell;
    ins = cellOffset + 2*i;
    rc = allocateSpace(pPage, sz, &idx);
    if( rc ){ *pRC = rc; return; }
    /* The allocateSpace() routine guarantees the following two properties
    ** if it returns success */
    assert( idx >= end+2 );
    assert( idx+sz <= (int)pPage->pBt->usableSize );
    pPage->nCell++;
    pPage->nFree -= (u16)(2 + sz);
    memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
    if( iChild ){
      put4byte(&data[idx], iChild);
    }
    for(j=end, ptr=&data[j]; j>ins; j-=2, ptr-=2){
................................................................................
  int cellbody;     /* Address of next cell body */
  u8 * const data = pPage->aData;             /* Pointer to data for pPage */
  const int hdr = pPage->hdrOffset;           /* Offset of header on pPage */
  const int nUsable = pPage->pBt->usableSize; /* Usable size of page */

  assert( pPage->nOverflow==0 );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( nCell>=0 && nCell<=(int)MX_CELL(pPage->pBt)
            && (int)MX_CELL(pPage->pBt)<=10921);
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );

  /* Check that the page has just been zeroed by zeroPage() */
  assert( pPage->nCell==0 );
  assert( get2byteNotZero(&data[hdr+5])==nUsable );

  pCellptr = &data[pPage->cellOffset + nCell*2];
................................................................................
    int const iToHdr = ((pTo->pgno==1) ? 100 : 0);
    int rc;
    int iData;
  
  
    assert( pFrom->isInit );
    assert( pFrom->nFree>=iToHdr );
    assert( get2byte(&aFrom[iFromHdr+5]) <= (int)pBt->usableSize );
  
    /* Copy the b-tree node content from page pFrom to page pTo. */
    iData = get2byte(&aFrom[iFromHdr+5]);
    memcpy(&aTo[iData], &aFrom[iData], pBt->usableSize-iData);
    memcpy(&aTo[iToHdr], &aFrom[iFromHdr], pFrom->cellOffset + 2*pFrom->nCell);
  
    /* Reinitialize page pTo so that the contents of the MemPage structure
................................................................................
      u16 sz = (u16)szNew[i];
      u8 *pTemp;
      assert( nCell<nMaxCells );
      szCell[nCell] = sz;
      pTemp = &aSpace1[iSpace1];
      iSpace1 += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iSpace1 <= (int)pBt->pageSize );
      memcpy(pTemp, apDiv[i], sz);
      apCell[nCell] = pTemp+leafCorrection;
      assert( leafCorrection==0 || leafCorrection==4 );
      szCell[nCell] = szCell[nCell] - leafCorrection;
      if( !pOld->leaf ){
        assert( leafCorrection==0 );
        assert( pOld->hdrOffset==0 );
................................................................................
    for(j=i+1; j<k; j++){
      if( apNew[j]->pgno<(unsigned)minV ){
        minI = j;
        minV = apNew[j]->pgno;
      }
    }
    if( minI>i ){

      MemPage *pT;

      pT = apNew[i];
      apNew[i] = apNew[minI];
      apNew[minI] = pT;
    }
  }
  TRACE(("new: %d(%d) %d(%d) %d(%d) %d(%d) %d(%d)\n",
    apNew[0]->pgno, szNew[0],
................................................................................
        if( szCell[j]==4 ){
          assert(leafCorrection==4);
          sz = cellSizePtr(pParent, pCell);
        }
      }
      iOvflSpace += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iOvflSpace <= (int)pBt->pageSize );
      insertCell(pParent, nxDiv, pCell, sz, pTemp, pNew->pgno, &rc);
      if( rc!=SQLITE_OK ) goto balance_cleanup;
      assert( sqlite3PagerIswriteable(pParent->pDbPage) );

      j++;
      nxDiv++;
    }
................................................................................
  assert( pPage->isInit );
  allocateTempSpace(pBt);
  newCell = pBt->pTmpSpace;
  if( newCell==0 ) return SQLITE_NOMEM;
  rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
  if( rc ) goto end_insert;
  assert( szNew==cellSizePtr(pPage, newCell) );
  assert( szNew <= MX_CELL_SIZE(pBt) );
  idx = pCur->aiIdx[pCur->iPage];
  if( loc==0 ){
    u16 szOld;
    assert( idx<pPage->nCell );
    rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc ){
      goto end_insert;
................................................................................
    MemPage *pLeaf = pCur->apPage[pCur->iPage];
    int nCell;
    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
    unsigned char *pTmp;

    pCell = findCell(pLeaf, pLeaf->nCell-1);
    nCell = cellSizePtr(pLeaf, pCell);
    assert( MX_CELL_SIZE(pBt) >= nCell );

    allocateTempSpace(pBt);
    pTmp = pBt->pTmpSpace;

    rc = sqlite3PagerWrite(pLeaf->pDbPage);
    insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
    dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);
................................................................................

#ifndef SQLITE_OMIT_WAL
/*
** Run a checkpoint on the Btree passed as the first argument.
**
** Return SQLITE_LOCKED if this or any other connection has an open 
** transaction on the shared-cache the argument Btree is connected to.
**
** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
*/
SQLITE_PRIVATE int sqlite3BtreeCheckpoint(Btree *p, int eMode, int *pnLog, int *pnCkpt){
  int rc = SQLITE_OK;
  if( p ){
    BtShared *pBt = p->pBt;
    sqlite3BtreeEnter(p);
    if( pBt->inTransaction!=TRANS_NONE ){
      rc = SQLITE_LOCKED;
    }else{
      rc = sqlite3PagerCheckpoint(pBt->pPager, eMode, pnLog, pnCkpt);
    }
    sqlite3BtreeLeave(p);
  }
  return rc;
}
#endif

................................................................................
**
** If the nBytes parameter is 0 and the blob of memory has not yet been
** allocated, a null pointer is returned. If the blob has already been
** allocated, it is returned as normal.
**
** Just before the shared-btree is closed, the function passed as the 
** xFree argument when the memory allocation was made is invoked on the 
** blob of allocated memory. The xFree function should not call sqlite3_free()
** on the memory, the btree layer does that.
*/
SQLITE_PRIVATE void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  if( !pBt->pSchema && nBytes ){
    pBt->pSchema = sqlite3DbMallocZero(0, nBytes);
................................................................................
*/
static int backupOnePage(sqlite3_backup *p, Pgno iSrcPg, const u8 *zSrcData){
  Pager * const pDestPager = sqlite3BtreePager(p->pDest);
  const int nSrcPgsz = sqlite3BtreeGetPageSize(p->pSrc);
  int nDestPgsz = sqlite3BtreeGetPageSize(p->pDest);
  const int nCopy = MIN(nSrcPgsz, nDestPgsz);
  const i64 iEnd = (i64)iSrcPg*(i64)nSrcPgsz;
#ifdef SQLITE_HAS_CODEC
  int nSrcReserve = sqlite3BtreeGetReserve(p->pSrc);
  int nDestReserve = sqlite3BtreeGetReserve(p->pDest);
#endif

  int rc = SQLITE_OK;
  i64 iOff;

  assert( p->bDestLocked );
  assert( !isFatalError(p->rc) );
  assert( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) );
................................................................................
  */
  if( nSrcPgsz!=nDestPgsz && sqlite3PagerIsMemdb(pDestPager) ){
    rc = SQLITE_READONLY;
  }

#ifdef SQLITE_HAS_CODEC
  /* Backup is not possible if the page size of the destination is changing
  ** and a codec is in use.
  */
  if( nSrcPgsz!=nDestPgsz && sqlite3PagerGetCodec(pDestPager)!=0 ){
    rc = SQLITE_READONLY;
  }

  /* Backup is not possible if the number of bytes of reserve space differ
  ** between source and destination.  If there is a difference, try to
  ** fix the destination to agree with the source.  If that is not possible,
  ** then the backup cannot proceed.
  */
  if( nSrcReserve!=nDestReserve ){
    u32 newPgsz = nSrcPgsz;
    rc = sqlite3PagerSetPagesize(pDestPager, &newPgsz, nSrcReserve);
    if( rc==SQLITE_OK && newPgsz!=nSrcPgsz ) rc = SQLITE_READONLY;
  }
#endif

  /* This loop runs once for each destination page spanned by the source 
  ** page. For each iteration, variable iOff is set to the byte offset
  ** of the destination page.
  */
  for(iOff=iEnd-(i64)nSrcPgsz; rc==SQLITE_OK && iOff<iEnd; iOff+=nDestPgsz){
................................................................................
    */
    if( rc==SQLITE_DONE 
     && (rc = sqlite3BtreeUpdateMeta(p->pDest,1,p->iDestSchema+1))==SQLITE_OK
    ){
      int nDestTruncate;
  
      if( p->pDestDb ){
        sqlite3ResetInternalSchema(p->pDestDb, -1);
      }

      /* Set nDestTruncate to the final number of pages in the destination
      ** database. The complication here is that the destination page
      ** size may be different to the source page size. 
      **
      ** If the source page size is smaller than the destination page size, 
................................................................................
        }
      }else{
        rc = sqlite3PagerCommitPhaseOne(pDestPager, 0, 0);
      }
  
      /* Finish committing the transaction to the destination database. */
      if( SQLITE_OK==rc
       && SQLITE_OK==(rc = sqlite3BtreeCommitPhaseTwo(p->pDest, 0))
      ){
        rc = SQLITE_DONE;
      }
    }
  
    /* If bCloseTrans is true, then this function opened a read transaction
    ** on the source database. Close the read transaction here. There is
    ** no need to check the return values of the btree methods here, as
    ** "committing" a read-only transaction cannot fail.
    */
    if( bCloseTrans ){
      TESTONLY( int rc2 );
      TESTONLY( rc2  = ) sqlite3BtreeCommitPhaseOne(p->pSrc, 0);
      TESTONLY( rc2 |= ) sqlite3BtreeCommitPhaseTwo(p->pSrc, 0);
      assert( rc2==SQLITE_OK );
    }
  
    if( rc==SQLITE_IOERR_NOMEM ){
      rc = SQLITE_NOMEM;
    }
    p->rc = rc;
................................................................................
  for(p=pBackup; p; p=p->pNext){
    assert( sqlite3_mutex_held(p->pSrc->pBt->mutex) );
    if( !isFatalError(p->rc) && iPage<p->iNext ){
      /* The backup process p has already copied page iPage. But now it
      ** has been modified by a transaction on the source pager. Copy
      ** the new data into the backup.
      */
      int rc;
      assert( p->pDestDb );
      sqlite3_mutex_enter(p->pDestDb->mutex);
      rc = backupOnePage(p, iPage, aData);
      sqlite3_mutex_leave(p->pDestDb->mutex);
      assert( rc!=SQLITE_BUSY && rc!=SQLITE_LOCKED );
      if( rc!=SQLITE_OK ){
        p->rc = rc;
      }
    }
  }
}
................................................................................
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
  flags = pMem->flags;
  if( flags & MEM_Int ){
    return pMem->u.i;
  }else if( flags & MEM_Real ){
    return doubleToInt64(pMem->r);
  }else if( flags & (MEM_Str|MEM_Blob) ){
    i64 value = 0;
    assert( pMem->z || pMem->n==0 );
    testcase( pMem->z==0 );
    sqlite3Atoi64(pMem->z, &value, pMem->n, pMem->enc);
    return value;
  }else{
    return 0;
  }
................................................................................
    if( enc!=SQLITE_UTF8 ){
      sqlite3VdbeChangeEncoding(pVal, enc);
    }
  }else if( op==TK_UMINUS ) {
    /* This branch happens for multiple negative signs.  Ex: -(-5) */
    if( SQLITE_OK==sqlite3ValueFromExpr(db,pExpr->pLeft,enc,affinity,&pVal) ){
      sqlite3VdbeMemNumerify(pVal);
      if( pVal->u.i==SMALLEST_INT64 ){
        pVal->flags &= MEM_Int;
        pVal->flags |= MEM_Real;
        pVal->r = (double)LARGEST_INT64;
      }else{
        pVal->u.i = -pVal->u.i;
      }
      pVal->r = -pVal->r;
      sqlite3ValueApplyAffinity(pVal, affinity, enc);
    }
  }else if( op==TK_NULL ){
    pVal = sqlite3ValueNew(db);
    if( pVal==0 ) goto no_mem;
  }
#ifndef SQLITE_OMIT_BLOB_LITERAL
  else if( op==TK_BLOB ){
    int nVal;
    assert( pExpr->u.zToken[0]=='x' || pExpr->u.zToken[0]=='X' );
    assert( pExpr->u.zToken[1]=='\'' );
    pVal = sqlite3ValueNew(db);
................................................................................
  pOp->p5 = 0;
  pOp->p1 = p1;
  pOp->p2 = p2;
  pOp->p3 = p3;
  pOp->p4.p = 0;
  pOp->p4type = P4_NOTUSED;
  p->expired = 0;
  if( op==OP_ParseSchema ){
    /* Any program that uses the OP_ParseSchema opcode needs to lock
    ** all btrees. */
    int j;
    for(j=0; j<p->db->nDb; j++) sqlite3VdbeUsesBtree(p, j);
  }
#ifdef SQLITE_DEBUG
  pOp->zComment = 0;
  if( sqlite3VdbeAddopTrace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]);
#endif
#ifdef VDBE_PROFILE
  pOp->cycles = 0;
  pOp->cnt = 0;
................................................................................
** returned program.
*/
SQLITE_PRIVATE VdbeOp *sqlite3VdbeTakeOpArray(Vdbe *p, int *pnOp, int *pnMaxArg){
  VdbeOp *aOp = p->aOp;
  assert( aOp && !p->db->mallocFailed );

  /* Check that sqlite3VdbeUsesBtree() was not called on this VM */
  assert( p->btreeMask==0 );

  resolveP2Values(p, pnMaxArg);
  *pnOp = p->nOp;
  p->aOp = 0;
  return aOp;
}

................................................................................
}

/*
** Change the P2 operand of instruction addr so that it points to
** the address of the next instruction to be coded.
*/
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe *p, int addr){
  assert( addr>=0 );
  sqlite3VdbeChangeP2(p, addr, p->nOp);
}


/*
** If the input FuncDef structure is ephemeral, then free it.  If
** the FuncDef is not ephermal, then do nothing.
................................................................................
  return zP4;
}
#endif

/*
** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
**
** The prepared statements need to know in advance the complete set of
** attached databases that they will be using.  A mask of these databases
** is maintained in p->btreeMask and is used for locking and other purposes.

*/
SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe *p, int i){

  assert( i>=0 && i<p->db->nDb && i<(int)sizeof(yDbMask)*8 );
  assert( i<(int)sizeof(p->btreeMask)*8 );


  p->btreeMask |= ((yDbMask)1)<<i;

  if( i!=1 && sqlite3BtreeSharable(p->db->aDb[i].pBt) ){
    p->lockMask |= ((yDbMask)1)<<i;
  }
}

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
/*
** If SQLite is compiled to support shared-cache mode and to be threadsafe,
** this routine obtains the mutex associated with each BtShared structure
** that may be accessed by the VM passed as an argument. In doing so it also
** sets the BtShared.db member of each of the BtShared structures, ensuring
** that the correct busy-handler callback is invoked if required.
**
** If SQLite is not threadsafe but does support shared-cache mode, then
** sqlite3BtreeEnter() is invoked to set the BtShared.db variables
** of all of BtShared structures accessible via the database handle 
** associated with the VM.
**
** If SQLite is not threadsafe and does not support shared-cache mode, this
** function is a no-op.
**
** The p->btreeMask field is a bitmask of all btrees that the prepared 
** statement p will ever use.  Let N be the number of bits in p->btreeMask
** corresponding to btrees that use shared cache.  Then the runtime of
** this routine is N*N.  But as N is rarely more than 1, this should not
** be a problem.
*/
SQLITE_PRIVATE void sqlite3VdbeEnter(Vdbe *p){
  int i;
  yDbMask mask;
  sqlite3 *db;
  Db *aDb;
  int nDb;
  if( p->lockMask==0 ) return;  /* The common case */
  db = p->db;
  aDb = db->aDb;
  nDb = db->nDb;
  for(i=0, mask=1; i<nDb; i++, mask += mask){
    if( i!=1 && (mask & p->lockMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
      sqlite3BtreeEnter(aDb[i].pBt);
    }
  }
}
#endif

#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
/*
** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
*/
SQLITE_PRIVATE void sqlite3VdbeLeave(Vdbe *p){
  int i;
  yDbMask mask;
  sqlite3 *db;
  Db *aDb;
  int nDb;
  if( p->lockMask==0 ) return;  /* The common case */
  db = p->db;
  aDb = db->aDb;
  nDb = db->nDb;
  for(i=0, mask=1; i<nDb; i++, mask += mask){
    if( i!=1 && (mask & p->lockMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
      sqlite3BtreeLeave(aDb[i].pBt);
    }
  }
}
#endif

#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
SQLITE_PRIVATE void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){
  char *zP4;
................................................................................
** Also release any dynamic memory held by the VM in the Vdbe.aMem memory 
** cell array. This is necessary as the memory cell array may contain
** pointers to VdbeFrame objects, which may in turn contain pointers to
** open cursors.
*/
static void closeAllCursors(Vdbe *p){
  if( p->pFrame ){
    VdbeFrame *pFrame;
    for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
    sqlite3VdbeFrameRestore(pFrame);
  }
  p->pFrame = 0;
  p->nFrame = 0;

  if( p->apCsr ){
................................................................................
    ** If one of the BtreeCommitPhaseOne() calls fails, this indicates an
    ** IO error while deleting or truncating a journal file. It is unlikely,
    ** but could happen. In this case abandon processing and return the error.
    */
    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
      Btree *pBt = db->aDb[i].pBt;
      if( pBt ){
        rc = sqlite3BtreeCommitPhaseTwo(pBt, 0);
      }
    }
    if( rc==SQLITE_OK ){
      sqlite3VtabCommit(db);
    }
  }

................................................................................
    ** may be lying around. Returning an error code won't help matters.
    */
    disable_simulated_io_errors();
    sqlite3BeginBenignMalloc();
    for(i=0; i<db->nDb; i++){ 
      Btree *pBt = db->aDb[i].pBt;
      if( pBt ){
        sqlite3BtreeCommitPhaseTwo(pBt, 1);
      }
    }
    sqlite3EndBenignMalloc();
    enable_simulated_io_errors();

    sqlite3VtabCommit(db);
  }
................................................................................
    if( eOp==SAVEPOINT_ROLLBACK ){
      db->nDeferredCons = p->nStmtDefCons;
    }
  }
  return rc;
}




























/*
** This function is called when a transaction opened by the database 
** handle associated with the VM passed as an argument is about to be 
** committed. If there are outstanding deferred foreign key constraint
** violations, return SQLITE_ERROR. Otherwise, SQLITE_OK.
**
** If there are outstanding FK violations and this function returns 
................................................................................
  /* No commit or rollback needed if the program never started */
  if( p->pc>=0 ){
    int mrc;   /* Primary error code from p->rc */
    int eStatementOp = 0;
    int isSpecialError;            /* Set to true if a 'special' error */

    /* Lock all btrees used by the statement */
    sqlite3VdbeEnter(p);

    /* Check for one of the special errors */
    mrc = p->rc & 0xff;
    assert( p->rc!=SQLITE_IOERR_BLOCKED );  /* This error no longer exists */
    isSpecialError = mrc==SQLITE_NOMEM || mrc==SQLITE_IOERR
                     || mrc==SQLITE_INTERRUPT || mrc==SQLITE_FULL;
    if( isSpecialError ){
................................................................................
    ** above has occurred. 
    */
    if( !sqlite3VtabInSync(db) 
     && db->autoCommit 
     && db->writeVdbeCnt==(p->readOnly==0) 
    ){
      if( p->rc==SQLITE_OK || (p->errorAction==OE_Fail && !isSpecialError) ){
        rc = sqlite3VdbeCheckFk(p, 1);
        if( rc!=SQLITE_OK ){
          if( NEVER(p->readOnly) ){
            sqlite3VdbeLeave(p);
            return SQLITE_ERROR;
          }
          rc = SQLITE_CONSTRAINT;
        }else{ 
          /* The auto-commit flag is true, the vdbe program was successful 
          ** or hit an 'OR FAIL' constraint and there are no deferred foreign
          ** key constraints to hold up the transaction. This means a commit 
          ** is required. */
          rc = vdbeCommit(db, p);
        }
        if( rc==SQLITE_BUSY && p->readOnly ){

          sqlite3VdbeLeave(p);
          return SQLITE_BUSY;
        }else if( rc!=SQLITE_OK ){
          p->rc = rc;
          sqlite3RollbackAll(db);
        }else{
          db->nDeferredCons = 0;
          sqlite3CommitInternalChanges(db);
................................................................................
        sqlite3VdbeSetChanges(db, 0);
      }
      p->nChange = 0;
    }
  
    /* Rollback or commit any schema changes that occurred. */
    if( p->rc!=SQLITE_OK && db->flags&SQLITE_InternChanges ){
      sqlite3ResetInternalSchema(db, -1);
      db->flags = (db->flags | SQLITE_InternChanges);
    }

    /* Release the locks */
    sqlite3VdbeLeave(p);
  }

  /* We have successfully halted and closed the VM.  Record this fact. */
  if( p->pc>=0 ){
    db->activeVdbeCnt--;
    if( !p->readOnly ){
      db->writeVdbeCnt--;
................................................................................
  ** to invoke any required unlock-notify callbacks.
  */
  if( db->autoCommit ){
    sqlite3ConnectionUnlocked(db);
  }

  assert( db->activeVdbeCnt>0 || db->autoCommit==0 || db->nStatement==0 );
  return (p->rc==SQLITE_BUSY ? SQLITE_BUSY : SQLITE_OK);
}


/*
** Each VDBE holds the result of the most recent sqlite3_step() call
** in p->rc.  This routine sets that result back to SQLITE_OK.
*/
................................................................................
    /* Figure out whether to use 1, 2, 4, 6 or 8 bytes. */
#   define MAX_6BYTE ((((i64)0x00008000)<<32)-1)
    i64 i = pMem->u.i;
    u64 u;
    if( file_format>=4 && (i&1)==i ){
      return 8+(u32)i;
    }
    if( i<0 ){
      if( i<(-MAX_6BYTE) ) return 6;
      /* Previous test prevents:  u = -(-9223372036854775808) */
      u = -i;
    }else{
      u = i;
    }
    if( u<=127 ) return 1;
    if( u<=32767 ) return 2;
    if( u<=8388607 ) return 3;
    if( u<=2147483647 ) return 4;
    if( u<=MAX_6BYTE ) return 5;
    return 6;
  }
................................................................................
** Check to see if column iCol of the given statement is valid.  If
** it is, return a pointer to the Mem for the value of that column.
** If iCol is not valid, return a pointer to a Mem which has a value
** of NULL.
*/
static Mem *columnMem(sqlite3_stmt *pStmt, int i){
  Vdbe *pVm;

  Mem *pOut;

  pVm = (Vdbe *)pStmt;
  if( pVm && pVm->pResultSet!=0 && i<pVm->nResColumn && i>=0 ){
    sqlite3_mutex_enter(pVm->db->mutex);

    pOut = &pVm->pResultSet[i];
  }else{
    /* If the value passed as the second argument is out of range, return
    ** a pointer to the following static Mem object which contains the
    ** value SQL NULL. Even though the Mem structure contains an element
    ** of type i64, on certain architecture (x86) with certain compiler
    ** switches (-Os), gcc may align this Mem object on a 4-byte boundary
................................................................................
    ** this assert() from failing, when building with SQLITE_DEBUG defined
    ** using gcc, force nullMem to be 8-byte aligned using the magical
    ** __attribute__((aligned(8))) macro.  */
    static const Mem nullMem 
#if defined(SQLITE_DEBUG) && defined(__GNUC__)
      __attribute__((aligned(8))) 
#endif
      = {0, "", (double)0, {0}, 0, MEM_Null, SQLITE_NULL, 0,
#ifdef SQLITE_DEBUG
         0, 0,  /* pScopyFrom, pFiller */
#endif
         0, 0 };

    if( pVm && ALWAYS(pVm->db) ){
      sqlite3_mutex_enter(pVm->db->mutex);
      sqlite3Error(pVm->db, SQLITE_RANGE, 0);
    }
    pOut = (Mem*)&nullMem;
  }
................................................................................
                      db->aLimit[SQLITE_LIMIT_LENGTH]);
  out.db = db;
  if( db->vdbeExecCnt>1 ){
    while( *zRawSql ){
      const char *zStart = zRawSql;
      while( *(zRawSql++)!='\n' && *zRawSql );
      sqlite3StrAccumAppend(&out, "-- ", 3);
      sqlite3StrAccumAppend(&out, zStart, (int)(zRawSql-zStart));
    }
  }else{
    while( zRawSql[0] ){
      n = findNextHostParameter(zRawSql, &nToken);
      assert( n>0 );
      sqlite3StrAccumAppend(&out, zRawSql, n);
      zRawSql += n;
................................................................................
  Vdbe *p                    /* The VDBE */
){
  int pc=0;                  /* The program counter */
  Op *aOp = p->aOp;          /* Copy of p->aOp */
  Op *pOp;                   /* Current operation */
  int rc = SQLITE_OK;        /* Value to return */
  sqlite3 *db = p->db;       /* The database */
  u8 resetSchemaOnFault = 0; /* Reset schema after an error if positive */
  u8 encoding = ENC(db);     /* The database encoding */
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int checkProgress;         /* True if progress callbacks are enabled */
  int nProgressOps = 0;