コード例 #1
0
ファイル: SqlFileStream.cs プロジェクト: winseros/SqlClient
        private void OpenSqlFileStream
        (
            string path,
            byte[] transactionContext,
            System.IO.FileAccess access,
            System.IO.FileOptions options,
            Int64 allocationSize
        )
        {
            //-----------------------------------------------------------------
            // precondition validation

            // these should be checked by any caller of this method

            // ensure we have validated and normalized the path before
            Debug.Assert(path != null);
            Debug.Assert(transactionContext != null);

            if (access != FileAccess.Read && access != FileAccess.Write && access != FileAccess.ReadWrite)
            {
                throw ADP.ArgumentOutOfRange("access");
            }

            // FileOptions is a set of flags, so AND the given value against the set of values we do not support
            if ((options & ~(FileOptions.WriteThrough | FileOptions.Asynchronous | FileOptions.RandomAccess | FileOptions.SequentialScan)) != 0)
            {
                throw ADP.ArgumentOutOfRange("options");
            }

            //-----------------------------------------------------------------

            // normalize the provided path
            //   * compress path to remove any occurrences of '.' or '..'
            //   * trim whitespace from the beginning and end of the path
            //   * ensure that the path starts with '\\'
            //   * ensure that the path does not start with '\\.\'
            //   * ensure that the path is not longer than Int16.MaxValue
            path = GetFullPathInternal(path);

            // ensure the running code has permission to read/write the file
            DemandAccessPermission(path, access);

            FileFullEaInformation    eaBuffer   = null;
            SecurityQualityOfService qos        = null;
            UnicodeString            objectName = null;

            Microsoft.Win32.SafeHandles.SafeFileHandle hFile = null;

            int nDesiredAccess = UnsafeNativeMethods.FILE_READ_ATTRIBUTES | UnsafeNativeMethods.SYNCHRONIZE;

            UInt32 dwCreateOptions     = 0;
            UInt32 dwCreateDisposition = 0;

            System.IO.FileShare shareAccess = System.IO.FileShare.None;

            switch (access)
            {
            case System.IO.FileAccess.Read:
                nDesiredAccess     |= UnsafeNativeMethods.FILE_READ_DATA;
                shareAccess         = System.IO.FileShare.Delete | System.IO.FileShare.ReadWrite;
                dwCreateDisposition = (uint)UnsafeNativeMethods.CreationDisposition.FILE_OPEN;
                break;

            case System.IO.FileAccess.Write:
                nDesiredAccess     |= UnsafeNativeMethods.FILE_WRITE_DATA;
                shareAccess         = System.IO.FileShare.Delete | System.IO.FileShare.Read;
                dwCreateDisposition = (uint)UnsafeNativeMethods.CreationDisposition.FILE_OVERWRITE;
                break;

            case System.IO.FileAccess.ReadWrite:
            default:
                // we validate the value of 'access' parameter in the beginning of this method
                Debug.Assert(access == System.IO.FileAccess.ReadWrite);

                nDesiredAccess     |= UnsafeNativeMethods.FILE_READ_DATA | UnsafeNativeMethods.FILE_WRITE_DATA;
                shareAccess         = System.IO.FileShare.Delete | System.IO.FileShare.Read;
                dwCreateDisposition = (uint)UnsafeNativeMethods.CreationDisposition.FILE_OVERWRITE;
                break;
            }

            if ((options & System.IO.FileOptions.WriteThrough) != 0)
            {
                dwCreateOptions |= (uint)UnsafeNativeMethods.CreateOption.FILE_WRITE_THROUGH;
            }

            if ((options & System.IO.FileOptions.Asynchronous) == 0)
            {
                dwCreateOptions |= (uint)UnsafeNativeMethods.CreateOption.FILE_SYNCHRONOUS_IO_NONALERT;
            }

            if ((options & System.IO.FileOptions.SequentialScan) != 0)
            {
                dwCreateOptions |= (uint)UnsafeNativeMethods.CreateOption.FILE_SEQUENTIAL_ONLY;
            }

            if ((options & System.IO.FileOptions.RandomAccess) != 0)
            {
                dwCreateOptions |= (uint)UnsafeNativeMethods.CreateOption.FILE_RANDOM_ACCESS;
            }

            try
            {
                eaBuffer = new FileFullEaInformation(transactionContext);

                qos = new SecurityQualityOfService(UnsafeNativeMethods.SecurityImpersonationLevel.SecurityAnonymous,
                                                   false, false);

                // NOTE: the Name property is intended to reveal the publicly available moniker for the
                //   FILESTREAM attributed column data. We will not surface the internal processing that
                //   takes place to create the mappedPath.
                string mappedPath = InitializeNtPath(path);
                objectName = new UnicodeString(mappedPath);

                UnsafeNativeMethods.OBJECT_ATTRIBUTES oa;
                oa.length                   = Marshal.SizeOf(typeof(UnsafeNativeMethods.OBJECT_ATTRIBUTES));
                oa.rootDirectory            = IntPtr.Zero;
                oa.attributes               = (int)UnsafeNativeMethods.Attributes.CaseInsensitive;
                oa.securityDescriptor       = IntPtr.Zero;
                oa.securityQualityOfService = qos;
                oa.objectName               = objectName;

                UnsafeNativeMethods.IO_STATUS_BLOCK ioStatusBlock;

                uint oldMode;
                uint retval = 0;

                UnsafeNativeMethods.SetErrorModeWrapper(UnsafeNativeMethods.SEM_FAILCRITICALERRORS, out oldMode);
                try
                {
                    SqlClientEventSource.Log.TryAdvancedTraceEvent("<sc.SqlFileStream.OpenSqlFileStream|ADV> {0}, desiredAccess=0x{1}, allocationSize={2}, " +
                                                                   "fileAttributes=0x{3}, shareAccess=0x{4}, dwCreateDisposition=0x{5}, createOptions=0x{ dwCreateOptions}", ObjectID, (int)nDesiredAccess, allocationSize, 0, (int)shareAccess, dwCreateDisposition);

                    retval = UnsafeNativeMethods.NtCreateFile(out hFile, nDesiredAccess,
                                                              ref oa, out ioStatusBlock, ref allocationSize,
                                                              0, shareAccess, dwCreateDisposition, dwCreateOptions,
                                                              eaBuffer, (uint)eaBuffer.Length);
                }
                finally
                {
                    UnsafeNativeMethods.SetErrorModeWrapper(oldMode, out oldMode);
                }

                switch (retval)
                {
                case 0:
                    break;

                case UnsafeNativeMethods.STATUS_SHARING_VIOLATION:
                    throw ADP.InvalidOperation(StringsHelper.GetString(StringsHelper.SqlFileStream_FileAlreadyInTransaction));

                case UnsafeNativeMethods.STATUS_INVALID_PARAMETER:
                    throw ADP.Argument(StringsHelper.GetString(StringsHelper.SqlFileStream_InvalidParameter));

                case UnsafeNativeMethods.STATUS_OBJECT_NAME_NOT_FOUND:
                {
                    System.IO.DirectoryNotFoundException e = new System.IO.DirectoryNotFoundException();
                    ADP.TraceExceptionAsReturnValue(e);
                    throw e;
                }

                default:
                {
                    uint error = UnsafeNativeMethods.RtlNtStatusToDosError(retval);
                    if (error == UnsafeNativeMethods.ERROR_MR_MID_NOT_FOUND)
                    {
                        // status code could not be mapped to a Win32 error code
                        error = retval;
                    }

                    System.ComponentModel.Win32Exception e = new System.ComponentModel.Win32Exception(unchecked ((int)error));
                    ADP.TraceExceptionAsReturnValue(e);
                    throw e;
                }
                }

                if (hFile.IsInvalid)
                {
                    System.ComponentModel.Win32Exception e = new System.ComponentModel.Win32Exception(UnsafeNativeMethods.ERROR_INVALID_HANDLE);
                    ADP.TraceExceptionAsReturnValue(e);
                    throw e;
                }

                UnsafeNativeMethods.FileType fileType = UnsafeNativeMethods.GetFileType(hFile);
                if (fileType != UnsafeNativeMethods.FileType.Disk)
                {
                    hFile.Dispose();
                    throw ADP.Argument(StringsHelper.GetString(StringsHelper.SqlFileStream_PathNotValidDiskResource));
                }

                // if the user is opening the SQL FileStream in read/write mode, we assume that they want to scan
                //   through current data and then append new data to the end, so we need to tell SQL Server to preserve
                //   the existing file contents.
                if (access == System.IO.FileAccess.ReadWrite)
                {
                    uint ioControlCode = UnsafeNativeMethods.CTL_CODE(UnsafeNativeMethods.FILE_DEVICE_FILE_SYSTEM,
                                                                      IoControlCodeFunctionCode, (byte)UnsafeNativeMethods.Method.METHOD_BUFFERED,
                                                                      (byte)UnsafeNativeMethods.Access.FILE_ANY_ACCESS);
                    uint cbBytesReturned = 0;

                    if (!UnsafeNativeMethods.DeviceIoControl(hFile, ioControlCode, IntPtr.Zero, 0, IntPtr.Zero, 0, out cbBytesReturned, IntPtr.Zero))
                    {
                        System.ComponentModel.Win32Exception e = new System.ComponentModel.Win32Exception(Marshal.GetLastWin32Error());
                        ADP.TraceExceptionAsReturnValue(e);
                        throw e;
                    }
                }

                // now that we've successfully opened a handle on the path and verified that it is a file,
                //   use the SafeFileHandle to initialize our internal System.IO.FileStream instance
                // NOTE: need to assert UnmanagedCode permissions for this constructor. This is relatively benign
                //   in that we've done much the same validation as in the FileStream(string path, ...) ctor case
                //   most notably, validating that the handle type corresponds to an on-disk file.
                bool bRevertAssert = false;
                try
                {
                    SecurityPermission sp = new SecurityPermission(SecurityPermissionFlag.UnmanagedCode);
                    sp.Assert();
                    bRevertAssert = true;

                    System.Diagnostics.Debug.Assert(m_fs == null);
                    m_fs = new System.IO.FileStream(hFile, access, DefaultBufferSize, ((options & System.IO.FileOptions.Asynchronous) != 0));
                }
                finally
                {
                    if (bRevertAssert)
                    {
                        SecurityPermission.RevertAssert();
                    }
                }
            }
            catch
            {
                if (hFile != null && !hFile.IsInvalid)
                {
                    hFile.Dispose();
                }

                throw;
            }
            finally
            {
                if (eaBuffer != null)
                {
                    eaBuffer.Dispose();
                    eaBuffer = null;
                }

                if (qos != null)
                {
                    qos.Dispose();
                    qos = null;
                }

                if (objectName != null)
                {
                    objectName.Dispose();
                    objectName = null;
                }
            }
        }