FSCTL_TXFS_QUERY_RM_INFORMATION control code

[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.]

Retrieves information for a resource manager (RM).

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


BOOL 
DeviceIoControl(
  (HANDLE) hDevice,                // handle to device
  FSCTL_TXFS_QUERY_RM_INFORMATION, // dwIoControlCode
  NULL,                            // lpInBuffer
  0,                               // nInBufferSize
  (LPVOID) lpOutBuffer,            // output buffer
  (DWORD) nOutBufferSize,          // size of output buffer
  (LPDWORD) lpBytesReturned,       // bytes returned
  (LPOVERLAPPED) lpOverlapped );   // OVERLAPPED structure

Parameters

hDevice

A handle to the directory that is the root of the directory tree for the RM.

dwIoControlCode

The control code for the operation. Use FSCTL_TXFS_QUERY_RM_INFORMATION for this operation.

lpInBuffer

Not used with this operation; set to NULL.

nInBufferSize

Not used with this operation; set to zero (0).

lpOutBuffer

A pointer to the output buffer, a TXFS_QUERY_RM_INFORMATION structure.

nOutBufferSize

The size of the output buffer, in bytes.

lpBytesReturned

A 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 (0).

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

A 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.

Remarks

FSCTL_TXFS_QUERY_RM_INFORMATION is a synchronous operation.

If this call fails with ERROR_BUFFER_TOO_SMALL, the BytesRequired member of the TXFS_QUERY_RM_INFORMATION structure specifies how large the buffer must be for the call to return successfully.

If you are writing an application that supports remote Server Message Block Protocol clients, you must use this control code to use the resource manager.

The resource manager may be queried regardless of its state; if the RM is not started, ERROR_RM_NOT_ACTIVE is returned. You can use the information about the active range of the log to guide decisions about how much of the log to archive.

ReFS:  This code is not supported.

Requirements

Minimum supported client

Windows Vista [desktop apps only]

Minimum supported server

Windows Server 2008 [desktop apps only]

Header

WinIoCtl.h (include Windows.h)

See also

DeviceIoControl
Secondary Resource Managers for TxF Volumes
TXFS_QUERY_RM_INFORMATION

 

 

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