NTSTATUS
PiGetDeviceObjectFilePointer(
  IN  PUNICODE_STRING ObjectName,
  OUT PFILE_OBJECT *DeviceFileObject
  );

Routine Description:

    This routine returns a pointer to a referenced file object that has been
    opened to the specified device.

    To close access to the device, the caller should dereference the file
    object pointer.

Arguments:

    ObjectName - Name of the device object for which a file object pointer is
        to be returned.

    DeviceFileObject - Supplies the address of a variable to receive a pointer
        to the file object for the device.

Return Value:

    NT status code indicating whether the function was successful.