System.Data.SQLite

          used instead of the application base directory by the native
          library pre-loader.  This environment variable can be especially
          useful in ASP.NET and other hosted environments where direct control
          of the location of the managed assemblies is not under the control
          of the application.</td>
        </tr>
        <tr valign="top">
          <td>PreLoadSQLite_LibraryFileNameOnly</td>
          <td>If this configuration variable is set [to anything], it will be
          used as the base file name (without directory information) for the
          native SQLite library to be pre-loaded (e.g. "sqlite3.dll" or
          "libsqlite3.so.0").</td>
        </tr>
        <tr valign="top">
          <td>PreLoadSQLite_ProcessorArchitecture</td>
          <td>If this environment variable is set [to anything], it will be
          used instead of the processor architecture value contained in the
          PROCESSOR_ARCHITECTURE environment variable to help build the path

    <!--
    <add key="PreLoadSQLite_BaseDirectory" value="" />
    -->

    <!--
        NOTE: If this configuration variable is set [to anything], it will be
              used as the base file name (without directory information) for
              the native SQLite library to be pre-loaded (e.g. "sqlite3.dll"
              or "libsqlite3.so.0").
    -->
    <!--
    <add key="PreLoadSQLite_LibraryFileNameOnly" value="" />
    -->

    <!--
        NOTE: If this configuration variable is set [to anything], it will be
              used instead of the processor architecture value contained in the
              PROCESSOR_ARCHITECTURE environment variable to help build the
              path of the native library to pre-load.

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

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

#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 Unix dlopen
      /// function.  See the POSIX documentation for full details on what it
      /// does.
      /// </summary>
      /// <param name="fileName">
      /// The name of the executable library.
      /// </param>
      /// <param name="mode">
      /// This must be a combination of the individual bit flags RTLD_LAZY,
      /// RTLD_NOW, RTLD_GLOBAL, and/or RTLD_LOCAL.
      /// </param>
      /// <returns>
      /// The native module handle upon success -OR- IntPtr.Zero on failure.
      /// </returns>
      [DllImport("__Internal", EntryPoint = "dlopen",
          CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi,
          BestFitMapping = false, ThrowOnUnmappableChar = true,
          SetLastError = true)]
      private static extern IntPtr dlopen(string fileName, int mode);

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// For use with dlopen(), bind function calls lazily.
      /// </summary>
      private const int RTLD_LAZY = 0x1;

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// For use with dlopen(), bind function calls immediately.
      /// </summary>
      private const int RTLD_NOW = 0x2;

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// For use with dlopen(), make symbols globally available.
      /// </summary>
      private const int RTLD_GLOBAL = 0x100;

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// For use with dlopen(), opposite of RTLD_GLOBAL, and the default.
      /// </summary>
      private const int RTLD_LOCAL = 0x000;

      /////////////////////////////////////////////////////////////////////////
      /// <summary>
      /// For use with dlopen(), the defaults used by this class.
      /// </summary>
      private const int RTLD_DEFAULT = RTLD_NOW | RTLD_GLOBAL;
#endif

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

#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

      /// Determines the base file name (without any directory information)
      /// for the native SQLite library to be pre-loaded by this class.
      /// </summary>
      /// <returns>
      /// The base file name for the native SQLite library to be pre-loaded by
      /// this class -OR- null if its value cannot be determined.
      /// </returns>
      internal static string GetNativeLibraryFileNameOnly()
      {
          string fileNameOnly = GetSettingValue(
              "PreLoadSQLite_LibraryFileNameOnly", null);

          if (fileNameOnly != null)
              return fileNameOnly;

          return SQLITE_DLL;
      }

              return false; /* DISABLED */
          }

          //
          // NOTE: Determine the base file name for the native SQLite library.
          //       If this is not known by this class, we cannot continue.
          //
          string fileNameOnly = GetNativeLibraryFileNameOnly();

          if (fileNameOnly == null)
              return false;

          //
          // NOTE: Build the list of base directories and processor/platform
          //       names.  These lists will be used to help locate the native

          if (baseDirectory == null)
              return false;

          //
          // NOTE: Determine the base file name for the native SQLite library.
          //       If this is not known by this class, we cannot continue.
          //
          string fileNameOnly = GetNativeLibraryFileNameOnly();

          if (fileNameOnly == null)
              return false;

          //
          // NOTE: If the native SQLite library exists in the base directory
          //       itself, stop now.

                  // do nothing.
              }
#endif

              //
              // NOTE: Attempt to load the native library.  This will either
              //       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 ((Environment.OSVersion.Platform == PlatformID.Unix) ||
                  (Environment.OSVersion.Platform == PlatformID.MacOSX))
              {
                  nativeModuleHandle = dlopen(fileName, RTLD_DEFAULT);
              }
              else
#endif
              {
                  nativeModuleHandle = LoadLibrary(fileName);
              }

              return (nativeModuleHandle != IntPtr.Zero);
          }
#if !NET_COMPACT_20 && TRACE_PRELOAD
          catch (Exception e)
#else
          catch (Exception)