System.Data.SQLite

#endif

#if !PLATFORM_COMPACTFRAMEWORK && !DEBUG
  using System.Security;
#endif

  using System.Runtime.InteropServices;

#if !PLATFORM_COMPACTFRAMEWORK
  using System.Text;
#endif

#if !PLATFORM_COMPACTFRAMEWORK || COUNT_HANDLE
  using System.Threading;
#endif

  using System.Xml;

      internal static int backupCount;
#endif
      #endregion

      /////////////////////////////////////////////////////////////////////////

      #region Shared Native SQLite Library Pre-Loading Code
      #region Private Constants
      /// <summary>
      /// The file extension used for dynamic link libraries.
      /// </summary>
      private static readonly string DllFileExtension = ".dll";

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// The file extension used for the XML configuration file.
      /// </summary>
      private static readonly string ConfigFileExtension = ".config";

      /////////////////////////////////////////////////////////////////////////
      /// <summary>

      /// This is the name of the XML configuration file specific to the
      /// System.Data.SQLite assembly.
      /// </summary>
      private static readonly string XmlConfigFileName =
          typeof(UnsafeNativeMethods).Namespace + DllFileExtension +
          ConfigFileExtension;
      #endregion

      /////////////////////////////////////////////////////////////////////////

      #region Private Data
      /// <summary>
      /// This lock is used to protect the static _SQLiteNativeModuleFileName,
      /// _SQLiteNativeModuleHandle, and processorArchitecturePlatforms fields.
      /// </summary>
      private static readonly object staticSyncRoot = new object();

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// This dictionary stores the mappings between processor architecture
      /// names and platform names.  These mappings are now used for two
      /// purposes.  First, they are used to determine if the assembly code
      /// base should be used instead of the location, based upon whether one
      /// or more of the named sub-directories exist within the assembly code
      /// base.  Second, they are used to assist in loading the appropriate
      /// SQLite interop assembly into the current process.
      /// </summary>
      private static Dictionary<string, string> processorArchitecturePlatforms;
      #endregion

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// For now, this method simply calls the Initialize method.
      /// </summary>
      static UnsafeNativeMethods()
      {
          Initialize();
      }

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// Attempts to initialize this class by pre-loading the native SQLite
      /// library for the processor architecture of the current process.
      /// </summary>
      internal static void Initialize()
      {
#if SQLITE_STANDARD || USE_INTEROP_DLL || PLATFORM_COMPACTFRAMEWORK
#if PRELOAD_NATIVE_LIBRARY
          //
          // NOTE: If the "No_PreLoadSQLite" environment variable is set (to
          //       anything), skip all our special code and simply return.
          //
          if (GetSettingValue("No_PreLoadSQLite", null) != null)
              return;
#endif
#endif

          lock (staticSyncRoot)
          {
              //
              // TODO: Make sure this list is updated if the supported
              //       processor architecture names and/or platform names
              //       changes.
              //
              if (processorArchitecturePlatforms == null)
              {
                  //
                  // NOTE: Create the map of processor architecture names
                  //       to platform names using a case-insensitive string
                  //       comparer.
                  //
                  processorArchitecturePlatforms =
                      new Dictionary<string, string>(
                          StringComparer.OrdinalIgnoreCase);

                  //
                  // NOTE: Setup the list of platform names associated with
                  //       the supported processor architectures.
                  //
                  processorArchitecturePlatforms.Add("x86", "Win32");
                  processorArchitecturePlatforms.Add("AMD64", "x64");
                  processorArchitecturePlatforms.Add("IA64", "Itanium");
                  processorArchitecturePlatforms.Add("ARM", "WinCE");
              }

#if SQLITE_STANDARD || USE_INTEROP_DLL || PLATFORM_COMPACTFRAMEWORK
#if PRELOAD_NATIVE_LIBRARY
              //
              // BUGBUG: What about other application domains?
              //
              if (_SQLiteNativeModuleHandle == IntPtr.Zero)
              {
                  string baseDirectory = null;
                  string processorArchitecture = null;

                  /* IGNORED */
                  SearchForDirectory(
                      ref baseDirectory, ref processorArchitecture);

                  //
                  // NOTE: Attempt to pre-load the SQLite core library (or
                  //       interop assembly) and store both the file name
                  //       and native module handle for later usage.
                  //
                  /* IGNORED */
                  PreLoadSQLiteDll(
                      baseDirectory, processorArchitecture,
                      ref _SQLiteNativeModuleFileName,
                      ref _SQLiteNativeModuleHandle);
              }
#endif
#endif
          }
      }

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// Queries and returns the XML configuration file name for the assembly
      /// containing the managed System.Data.SQLite components.
      /// </summary>
      /// <returns>

                  // do nothing.
              }
#endif
          }

          return @default;
      }

      /////////////////////////////////////////////////////////////////////////

#if !PLATFORM_COMPACTFRAMEWORK
      private static string ListToString(IList<string> list)
      {
          if (list == null)
              return null;

          StringBuilder result = new StringBuilder();

          foreach (string element in list)
          {
              if (element == null)
                  continue;

              if (result.Length > 0)
                  result.Append(' ');

              result.Append(element);
          }

          return result.ToString();
      }

      /////////////////////////////////////////////////////////////////////////

      private static int CheckForArchitecturesAndPlatforms(
          string directory,
          ref List<string> matches
          )
      {
          int result = 0;

          if (matches == null)
              matches = new List<string>();

          lock (staticSyncRoot)
          {
              if (!String.IsNullOrEmpty(directory) &&
                  (processorArchitecturePlatforms != null))
              {
                  foreach (KeyValuePair<string, string> pair
                            in processorArchitecturePlatforms)
                  {
                      if (Directory.Exists(Path.Combine(directory, pair.Key)))
                      {
                          matches.Add(pair.Key);
                          result++;
                      }

                      string value = pair.Value;

                      if (value == null)
                          continue;

                      if (Directory.Exists(Path.Combine(directory, value)))
                      {
                          matches.Add(value);
                          result++;
                      }
                  }
              }
          }

          return result;
      }

      /////////////////////////////////////////////////////////////////////////

      private static bool CheckAssemblyCodeBase(
          Assembly assembly,
          ref string fileName
          )
      {
          try
          {
              if (assembly == null)
                  return false;

              string codeBase = assembly.CodeBase;

              if (String.IsNullOrEmpty(codeBase))
                  return false;

              Uri uri = new Uri(codeBase);
              string localFileName = uri.LocalPath;

              if (!File.Exists(localFileName))
                  return false;

              string directory = Path.GetDirectoryName(
                  localFileName); /* throw */

              string xmlConfigFileName = Path.Combine(
                  directory, XmlConfigFileName);

              if (File.Exists(xmlConfigFileName))
              {
#if !NET_COMPACT_20 && TRACE_SHARED
                  try
                  {
                      Trace.WriteLine(String.Format(
                          CultureInfo.CurrentCulture,
                          "Native library pre-loader found XML configuration file " +
                          "via code base for currently executing assembly: \"{0}\"",
                          xmlConfigFileName)); /* throw */
                  }
                  catch
                  {
                      // do nothing.
                  }
#endif

                  fileName = localFileName;
                  return true;
              }

              List<string> matches = null;

              if (CheckForArchitecturesAndPlatforms(directory, ref matches) > 0)
              {
#if !NET_COMPACT_20 && TRACE_SHARED
                  try
                  {
                      Trace.WriteLine(String.Format(
                          CultureInfo.CurrentCulture,
                          "Native library pre-loader found native sub-directories " +
                          "via code base for currently executing assembly: \"{0}\"",
                          ListToString(matches))); /* throw */
                  }
                  catch
                  {
                      // do nothing.
                  }
#endif

                  fileName = localFileName;
                  return true;
              }

              return false;
          }
#if !NET_COMPACT_20 && TRACE_SHARED
          catch (Exception e)
#else
          catch (Exception)
#endif
          {
#if !NET_COMPACT_20 && TRACE_SHARED
              try
              {
                  Trace.WriteLine(String.Format(
                      CultureInfo.CurrentCulture,
                      "Native library pre-loader failed to check code base " +
                      "for currently executing assembly: {0}", e)); /* throw */
              }
              catch
              {
                  // do nothing.
              }
#endif
          }

          return false;
      }
#endif

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// Queries and returns the directory for the assembly currently being
      /// executed.
      /// </summary>
      /// <returns>
      /// The directory for the assembly currently being executed -OR- null if
      /// it cannot be determined.
      /// </returns>
      private static string GetAssemblyDirectory()
      {
          try
          {
              Assembly assembly = Assembly.GetExecutingAssembly();

              if (assembly == null)
                  return null;

              string fileName = null;

#if PLATFORM_COMPACTFRAMEWORK
              AssemblyName assemblyName = assembly.GetName();

              if (assemblyName == null)
                  return null;

              fileName = assemblyName.CodeBase;
#else
              if (!CheckAssemblyCodeBase(assembly, ref fileName))
                  fileName = assembly.Location;
#endif

              if (String.IsNullOrEmpty(fileName))
                  return null;

              string directory = Path.GetDirectoryName(fileName);

          public uint dwAllocationGranularity; /* NOT USED */
          public ushort wProcessorLevel; /* NOT USED */
          public ushort wProcessorRevision; /* NOT USED */
      }
#endif

      /////////////////////////////////////////////////////////////////////////












      #region Private Data

      /// <summary>
      /// The native module file name for the native SQLite library or null.
      /// </summary>
      private static string _SQLiteNativeModuleFileName = null;

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// The native module handle for the native SQLite library or the value
      /// IntPtr.Zero.
      /// </summary>
      private static IntPtr _SQLiteNativeModuleHandle = IntPtr.Zero;
      #endregion













































































      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// Searches for the native SQLite library in the directory containing
      /// the assembly currently being executed as well as the base directory
      /// for the current application domain.
      /// </summary>