FSCTL_GET_REPARSE_POINT

Using the FSCTL_GET_REPARSE_POINT control code returns the reparse point data associated with the file or directory identified by the specified handle.

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

BOOL DeviceIoControl(
  (HANDLE) hDevice,            // handle to file or directory
  FSCTL_GET_REPARSE_POINT,     // dwIoControlCode operation
  NULL,                        // lpInBuffer; must be NULL
  0,                           // nInBufferSize; must be zero
  (LPVOID) lpOutBuffer,        // output buffer
  (DWORD) nOutBufferSize,      // size of output buffer
  (LPDWORD) lpBytesReturned,   // number of bytes returned
  (LPOVERLAPPED) lpOverlapped  // OVERLAPPED structure
);

Parameters

hDevice

[in] Handle to the file, alternate stream, or directory from which to obtain the reparse point data. Call the CreateFile function to obtain a handle.

dwIoControlCode

[in] Specifies the FSCTL_GET_REPARSE_POINT control code.

lpInBuffer

[in] Pointer to the input buffer. Not used; must be NULL.

nInBufferSize

[in] Size, in bytes, of the input buffer. Not used; must be zero.

lpOutBuffer

[out] Pointer to a REPARSE_GUID_DATA_BUFFER structure that receives the reparse point data.

nOutBufferSize

[in] Size, in bytes, of the output buffer. This value must be at least the size indicated by REPARSE_GUID_DATA_BUFFER_HEADER_SIZE, plus the size of the expected user-defined data.

lpBytesReturned

[out] Pointer to a variable that receives the size, in bytes, of output data returned.

If the output buffer is too small to return any data, then the call fails, GetLastError returns the error code ERROR_INSUFFICIENT_BUFFER, and the returned byte count is zero.

If the output buffer is too small to hold all of the data, then the operating system returns as much as fits, the call fails, GetLastError returns the error code ERROR_MORE_DATA, and lpBytesReturned indicates the amount of data returned. Your application should call DeviceIoControl again with the same operation and a larger buffer. Specify the maximum size, or determine the minimum length needed from the ReparseDataLength member of the REPARSE_GUID_DATA_BUFFER structure.

If lpOverlapped is NULL (nonoverlapped I/O), lpBytesReturned cannot be NULL.

If lpOverlapped is not NULL (overlapped I/O), lpBytesReturned can be NULL. If this is an overlapped operation, you can retrieve the number of bytes returned by calling the GetOverlappedResult function. If hDevice is associated with an I/O completion port, you can get the number of bytes returned by calling the GetQueuedCompletionStatus function.

lpOverlapped

[in] Pointer to an OVERLAPPED structure.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, lpOverlapped must point to a valid OVERLAPPED structure. In this case, the operation is performed as an overlapped (asynchronous) operation. If the device was opened with FILE_FLAG_OVERLAPPED and lpOverlapped is NULL, the function fails in unpredictable ways.

If hDevice was opened without specifying the FILE_FLAG_OVERLAPPED flag, lpOverlapped is ignored and DeviceIoControl does not return until the operation has been completed, or an error occurs.

Return Values

If the operation succeeds, DeviceIoControl returns a nonzero value, and the output buffer pointed to by lpOutBuffer contains a valid REPARSE_GUID_DATA_BUFFER structure, or a portion thereof, depending on the value of nOutBufferSize.

If the operation fails, DeviceIoControl returns zero. The contents of the output buffer pointed to by lpOutBuffer are meaningless. For extended error information, call GetLastError.

Remarks

For the implications of overlapped I/O on this operation, see the Remarks section of DeviceIoControl.

Requirements

  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Unsupported.
  Header: Declared in Winioctl.h.

See Also

Device Input and Output Overview, Device Input and Output Control Codes, CreateFile, DeviceIoControl, FSCTL_SET_REPARSE_POINT, FSCTL_DELETE_REPARSE_POINT, REPARSE_GUID_DATA_BUFFER