IOCTL_DISK_GET_DRIVE_LAYOUT

The IOCTL_DISK_GET_DRIVE_LAYOUT DeviceIoControl operation returns information about the number of partitions on a disk and the features of each partition.

BOOL DeviceIoControl(
  (HANDLE) hDevice,        // handle to device of interest
  IOCTL_DISK_GET_DRIVE_LAYOUT, // dwIoControlCode, control code of
                           // operation to perform
  NULL,                    // lpInBuffer is not used; must be NULL
  0,                       // nInBufferSize is not used; must be zero
  (LPVOID) lpOutBuffer,    // pointer to output buffer
  (DWORD) nOutBufferSize,  // size, in bytes, of lpOutBuffer
  (LPDWORD) lpBytesReturned,   // pointer to variable to receive
                           // output byte count
  (LPOVERLAPPED) lpOverlapped  // pointer to OVERLAPPED structure
                           // for asynchronous operation
);

Parameters

hDevice

Handle to the object on which the operation is to be performed. To obtain a device handle, call the CreateFile function.

dwIoControlCode

Control code for the operation. This value identifies the specific operation to be performed and the type of device on which the operation is to be performed. Use IOCTL_DISK_GET_DRIVE_LAYOUT for this operation.

lpInBuffer

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

nInBufferSize

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

lpOutBuffer

Pointer to a buffer that will receive a DRIVE_LAYOUT_INFORMATION structure and a series of PARTITION_INFORMATION structures, one of the latter for each partition on the drive.

nOutBufferSize

Size, in bytes, of the buffer pointed to by lpOutBuffer, which must be large enough to contain one DRIVE_LAYOUT_INFORMATION data structure and as many PARTITION_INFORMATION data structures as there are partitions on the drive.

lpBytesReturned

Pointer to a DWORD variable that receives the size, in bytes, of output data returned. If the lpOutBuffer buffer is too small, lpBytesReturned receives the required buffer size.

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

Pointer to an OVERLAPPED structure.

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

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

Return Values

If the operation succeeds, DeviceIoControl returns a nonzero value.

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

Remarks

This device I/O control operation is for disk devices. Floppy disk drivers, however, do not need to handle this operation.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Unsupported.
  Windows CE: Unsupported.
  Header: Declared in winioctl.h.

See Also

Device Input and Output Overview, Device Input and Output Operations, DeviceIoControl, DRIVE_LAYOUT_INFORMATION, IOCTL_DISK_SET_DRIVE_LAYOUT, PARTITION_INFORMATION