[Microsoft strongly recommends developers utilize alternative means to achieve your application’s needs. Many scenarios that TxF was developed for can be achieved through simpler and more readily available techniques. Furthermore, TxF may not be available in future versions of Microsoft Windows. For more information, and alternatives to TxF, please see Alternatives to using Transactional NTFS.]

Applies to: desktop apps only

The FSCTL_TXFS_SAVEPOINT_INFORMATION control code controls setting, clearing, and rolling back to the specified savepoint.

To perform this operation, call the DeviceIoControl function with the following parameters.

BOOL 
DeviceIoControl(
  (HANDLE) hDevice,                 // handle to resource manager
  FSCTL_TXFS_SAVEPOINT_INFORMATION, // dwIoControlCode
  (LPVOID)lpInBuffer ,              // input buffer
  (DWORD) nInBufferSize,            // size of input buffer
  (LPVOID) lpOutBuffer,             // output buffer
  (DWORD) nOutBufferSize,           // size of output buffer
  (LPDWORD) lpBytesReturned,        // number of bytes returned
  (LPOVERLAPPED) lpOverlapped );    // OVERLAPPED structure

Parameters

hDevice

A handle to the directory that is the root of the directory tree for the resource manager. This handle must include FILE_WRITE_DATA access rights (included in the GENERIC_WRITE generic access right).

dwIoControlCode

Control code for the operation. Use FSCTL_TXFS_SAVEPOINT_INFORMATION for this operation.

lpInBuffer

Pointer to the input buffer, a TXFS_SAVEPOINT_INFORMATION structure.

nInBufferSize

The size of the input buffer, in bytes.

lpOutBuffer [optional]

Pointer to the output buffer, a TXFS_SAVEPOINT_INFORMATION structure. This parameter is not used if the action specified is either TXFS_SAVEPOINT_CLEAR or TXFS_SAVEPOINT_CLEAR_ALL. If this parameter is not NULL, then it must be the same as the lpInBuffer parameter.

nOutBufferSize

The size of the output buffer, in bytes.

lpBytesReturned

Pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

If the output buffer is too small, the call fails, GetLastError returns ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero.

If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.

If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If hDevice is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.

lpOverlapped [optional]

Pointer to an OVERLAPPED structure.

If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.

For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.

Return value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails or is pending, DeviceIoControl returns zero. To get extended error information, call GetLastError.

Requirements

See also

DeviceIoControl

TXFS_SAVEPOINT_INFORMATION

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Build date: 4/17/2012