System.Data.SQLite

/********************************************************
 * ADO.NET 2.0 Data Provider for SQLite Version 3.X
 * Written by Robert Simpson (robert@blackcastlesoft.com)
 *
 * Released to the public domain, use at your own risk!
 ********************************************************/

namespace System.Data.SQLite
{
  using System;
  using System.Globalization;

      /// </summary>
      /// <param name="fileName">
      /// The name of the executable library.
      /// </param>
      /// <returns>
      /// The native module handle upon success -OR- IntPtr.Zero on failure.
      /// </returns>
#if !PLATFORM_COMPACTFRAMEWORK
      [DllImport("kernel32",
#else
      [DllImport("coredll",
#endif
          CallingConvention = CallingConvention.Winapi, CharSet = CharSet.Auto,
#if !PLATFORM_COMPACTFRAMEWORK
          BestFitMapping = false, ThrowOnUnmappableChar = true,
#endif
          SetLastError = true)]
      private static extern IntPtr LoadLibrary(string fileName);

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

#if PLATFORM_COMPACTFRAMEWORK
      /// <summary>
      /// This is the P/Invoke method that wraps the native Win32 GetSystemInfo
      /// function.  See the MSDN documentation for full details on what it
      /// does.
      /// </summary>
      /// <param name="systemInfo">
      /// The system information structure to be filled in by the function.
      /// </param>
      [DllImport("coredll", CallingConvention = CallingConvention.Winapi)]
      private static extern void GetSystemInfo(out SYSTEM_INFO systemInfo);

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// This enumeration contains the possible values for the processor
      /// architecture field of the system information structure.
      /// </summary>
      private enum ProcessorArchitecture : ushort /* COMPAT: Win32. */
      {
          Intel = 0,
          MIPS = 1,
          Alpha = 2,
          PowerPC = 3,
          SHx = 4,
          ARM = 5,
          IA64 = 6,
          Alpha64 = 7,
          MSIL = 8,
          AMD64 = 9,
          IA32_on_Win64 = 10,
          Unknown = 0xFFFF
      }

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// This structure contains information about the current computer. This
      /// includes the processor type, page size, memory addresses, etc.
      /// </summary>
      [StructLayout(LayoutKind.Sequential)]
      private struct SYSTEM_INFO
      {
          public ProcessorArchitecture wProcessorArchitecture;
          public ushort wReserved; /* NOT USED */
          public uint dwPageSize; /* NOT USED */
          public IntPtr lpMinimumApplicationAddress; /* NOT USED */
          public IntPtr lpMaximumApplicationAddress; /* NOT USED */
          public uint dwActiveProcessorMask; /* NOT USED */
          public uint dwNumberOfProcessors; /* NOT USED */
          public uint dwProcessorType; /* NOT USED */
          public uint dwAllocationGranularity; /* NOT USED */
          public ushort wProcessorLevel; /* NOT USED */
          public ushort wProcessorRevision; /* NOT USED */
      }
#endif

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// This lock is used to protect the static _SQLiteModule and
      /// processorArchitecturePlatforms fields, below.
      /// </summary>
      private static readonly object staticSyncRoot = new object();

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

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// Queries and returns the processor architecture of the current
      /// process.
      /// </summary>
      /// <returns>
      /// The processor architecture of the current process -OR- null if it
      /// cannot be determined.

      /// </returns>
      private static string GetProcessorArchitecture()
      {
#if !PLATFORM_COMPACTFRAMEWORK
          //
          // NOTE: If the "PreLoadSQLite_ProcessorArchitecture" environment
          //       variable is set, use it verbatim for the current processor

          //
          // BUGBUG: Will this always be reliable?
          //
          return Environment.GetEnvironmentVariable(PROCESSOR_ARCHITECTURE);
#else
          //
          // NOTE: On the .NET Compact Framework, attempt to use the native
          //       Win32 API function (via P/Invoke) that can provide us with
          //       the processor architecture.
          //
          try
          {
              //
              // NOTE: The output of the GetSystemInfo function will be placed
              //       here.  Only the processor architecture field is used by
              //       this method.
              //
              SYSTEM_INFO systemInfo;

              //
              // NOTE: Query the system information via P/Invoke, thus filling
              //       the structure.
              //
              GetSystemInfo(out systemInfo);

              //
              // NOTE: Return the processor architecture value as a string.
              //
              return systemInfo.wProcessorArchitecture.ToString();
          }
          catch
          {
              // do nothing.
          }

          //
          // NOTE: Upon failure, return an empty string.
          //
          return String.Empty;
#endif
      }

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

#else
    //
    // NOTE: Finally, assume that the mixed-mode assembly is being used.
    //
    private const string SQLITE_DLL = "System.Data.SQLite.dll";
#endif

    // This section uses interop calls that also fetch text length to optimize conversion.
    // When using the standard dll, we can replace these calls with normal sqlite calls and
    // do unoptimized conversions instead afterwards
    #region interop added textlength calls

#if !SQLITE_STANDARD

    [DllImport(SQLITE_DLL)]
    internal static extern IntPtr sqlite3_bind_parameter_name_interop(IntPtr stmt, int index, out int len);

    [DllImport(SQLITE_DLL, CallingConvention = CallingConvention.Cdecl)]
#else
    [DllImport(SQLITE_DLL)]
#endif
    internal static extern IntPtr sqlite3_errstr(SQLiteErrorCode rc); /* 3.7.15+ */

    // Since sqlite3_log() takes a variable argument list, we have to overload declarations
    // for all possible calls.  For now, we are only exposing a single string, and
    // depend on the caller to format the string.
#if !PLATFORM_COMPACTFRAMEWORK
    [DllImport(SQLITE_DLL, CallingConvention = CallingConvention.Cdecl)]
#else
    [DllImport(SQLITE_DLL)]
#endif
    internal static extern void sqlite3_log(SQLiteErrorCode iErrCode, byte[] zFormat);

  }

#if PLATFORM_COMPACTFRAMEWORK
  internal abstract class CriticalHandle : IDisposable
  {
    private bool _isClosed;
    protected IntPtr handle;

    protected CriticalHandle(IntPtr invalidHandleValue)
    {
      handle = invalidHandleValue;
      _isClosed = false;
    }

    ~CriticalHandle()