System.Data.SQLite

    protected Dictionary<SQLiteFunctionAttribute, SQLiteFunction> _functions;

#if INTEROP_VIRTUAL_TABLE
    /// <summary>
    /// This is the name of the native library file that contains the
    /// "vtshim" extension [wrapper].
    /// </summary>
    protected string _shimExtensionFileName = null;


    /// <summary>
    /// This is the flag indicate whether the native library file that
    /// contains the "vtshim" extension must be dynamically loaded by
    /// this class prior to use.
    /// </summary>
    protected bool? _shimIsLoadNeeded = null;

    /// <summary>
    /// This is the name of the native entry point for the "vtshim"
    /// extension [wrapper].
    /// </summary>
    protected string _shimExtensionProcName = "sqlite3_vtshim_init";

    internal override void ReturnText(IntPtr context, string value)
    {
      byte[] b = ToUTF8(value);
      UnsafeNativeMethods.sqlite3_result_text(context, ToUTF8(value), b.Length - 1, (IntPtr)(-1));
    }

#if INTEROP_VIRTUAL_TABLE
    /// <summary>
    /// Determines the file name of the native library containing the native
    /// "vtshim" extension -AND- whether it should be dynamically loaded by
    /// this class.
    /// </summary>
    /// <param name="isLoadNeeded">
    /// This output parameter will be set to non-zero if the returned native
    /// library file name should be dynamically loaded prior to attempting
    /// the creation of native disposable extension modules.
    /// </param>
    /// <returns>
    /// The file name of the native library containing the native "vtshim"
    /// extension -OR- null if it cannot be determined.
    /// </returns>
    private string GetShimExtensionFileName(
        ref bool isLoadNeeded /* out */
        )
    {
        if (_shimIsLoadNeeded != null)
            isLoadNeeded = (bool)_shimIsLoadNeeded;
        else
            isLoadNeeded = UnsafeNativeMethods.IsWindows(); /* COMPAT */

        string fileName = _shimExtensionFileName;

        if (fileName != null)
            return fileName;

#if (SQLITE_STANDARD || USE_INTEROP_DLL || PLATFORM_COMPACTFRAMEWORK) && PRELOAD_NATIVE_LIBRARY
        return UnsafeNativeMethods.GetNativeLibraryFileNameOnly(); /* COMPAT */
#else
        return null;
#endif
    }

    /// <summary>
    /// Calls the native SQLite core library in order to create a disposable
    /// module containing the implementation of a virtual table.
    /// </summary>
    /// <param name="module">
    /// The module object to be used when creating the native disposable module.
    /// </param>

            module.LogErrors = ((flags & SQLiteConnectionFlags.LogModuleError) == SQLiteConnectionFlags.LogModuleError);
            module.LogExceptions = ((flags & SQLiteConnectionFlags.LogModuleException) == SQLiteConnectionFlags.LogModuleException);
        }

        if (_sql == null)
            throw new SQLiteException("connection has an invalid handle");

        bool isLoadNeeded = false;
        string fileName = GetShimExtensionFileName(ref isLoadNeeded);

        if (isLoadNeeded)
        {
            if (fileName == null)
                throw new SQLiteException("the file name for the \"vtshim\" extension is unknown");

            if (_shimExtensionProcName == null)
                throw new SQLiteException("the entry point for the \"vtshim\" extension is unknown");

            SetLoadExtension(true);
            LoadExtension(fileName, _shimExtensionProcName);
        }

        if (module.CreateDisposableModule(_sql))
        {
            if (_modules == null)
                _modules = new Dictionary<string, SQLiteModule>();

            _modules.Add(module.Name, module);

          }

          return false;
      }

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

      /// <summary>
      /// Determines if the current process is running on one of the Windows
      /// [sub-]platforms.
      /// </summary>
      /// <returns>
      /// Non-zero when running on Windows; otherwise, zero.
      /// </returns>
      internal static bool IsWindows()
      {
          PlatformID platformId = Environment.OSVersion.Platform;

          if ((platformId == PlatformID.Win32S) ||
              (platformId == PlatformID.Win32Windows) ||
              (platformId == PlatformID.Win32NT) ||
              (platformId == PlatformID.WinCE))
          {
              return true;
          }

          return false;
      }

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

      /// <summary>
      /// This is a wrapper around the
      /// <see cref="String.Format(IFormatProvider,String,Object[])" /> method.
      /// On Mono, it has to call the method overload without the
      /// <see cref="IFormatProvider" /> parameter, due to a bug in Mono.
      /// </summary>
      /// <param name="provider">

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

      #region Private Data
      /// <summary>
      /// The native module file name for the native SQLite library or null.
      /// </summary>
      internal 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;

      {
          string fileNameOnly = GetSettingValue(
              "PreLoadSQLite_LibraryFileNameOnly", null);

          if (fileNameOnly != null)
              return fileNameOnly;

          return SQLITE_DLL; /* COMPAT */
      }

      /////////////////////////////////////////////////////////////////////////
      /// <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.

      /// </returns>
      private static string FixUpDllFileName(
          string fileName /* in */
          )
      {
          if (!String.IsNullOrEmpty(fileName))
          {

              if (IsWindows())




              {
                  if (!fileName.EndsWith(DllFileExtension,
                          StringComparison.OrdinalIgnoreCase))
                  {
                      return fileName + DllFileExtension;
                  }
              }

              //       return a valid native module handle, return IntPtr.Zero,
              //       or throw an exception.  This must use the appropriate
              //       P/Invoke method for the current operating system.
              //
              nativeModuleFileName = fileName;

#if !PLATFORM_COMPACTFRAMEWORK
              if (!IsWindows())

              {
                  nativeModuleHandle = dlopen(fileName, RTLD_DEFAULT);
              }
              else
#endif
              {
                  nativeModuleHandle = LoadLibrary(fileName);