Windows Dev Center

FSCTL_QUERY_FILE_SYSTEM_RECOGNITION control code

Queries for file system recognition information on a volume.

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


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

Parameters

hDevice [in]

A handle to the local volume from which data is to be retrieved.

To retrieve a volume handle, call the CreateFile function.

dwIoControlCode [in]

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

lpInBuffer

Not used with this operation; set to NULL.

nInBufferSize [in]

Not used with this operation; set to zero.

lpOutBuffer [out]

A pointer to the output buffer that receives a FILE_SYSTEM_RECOGNITION_INFORMATION structure that contains information about the file system for the volume referred to by the hDevice parameter.

nOutBufferSize [in]

The size of the output buffer, in bytes.

lpBytesReturned [out]

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.

If the lpOverlapped parameter 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 the GetOverlappedResult function. If the hDevice parameter is associated with an I/O completion port, you can retrieve the number of bytes returned by calling the GetQueuedCompletionStatus function.

lpOverlapped [in]

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

In Windows 8 and Windows Server 2012, this code is supported by the following technologies.

TechnologySupported

Server Message Block (SMB) 3.0 protocol

No

SMB 3.0 Transparent Failover (TFO)

No

SMB 3.0 with Scale-out File Shares (SO)

No

Cluster Shared Volume File System (CsvFS)

No

 

Requirements

Minimum supported client

Windows 7 [desktop apps only]

Minimum supported server

Windows Server 2008 R2 [desktop apps only]

Header

WinIoCtl.h (include Windows.h)

See also

DeviceIoControl
File System Recognition
FILE_SYSTEM_RECOGNITION_INFORMATION
FILE_SYSTEM_RECOGNITION_STRUCTURE

 

 

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