BOOLEAN
FatReadBlock(
  IN  PDEVICE_OBJECT DeviceObject,
  IN  PLARGE_INTEGER ByteOffset,
  IN  ULONG MinimumBytes,
  OUT PNTSTATUS ExtendedStatus,
  OUT PPACKED_BOOT_SECTOR *Buffer
  );

Routine Description:

    This routine reads a minimum numbers of bytes into a buffer starting at
    the byte offset from the base of the device represented by the device
    object.

Arguments:

    DeviceObject - Pointer to the device object from which to read.

    ByteOffset - Pointer to a 64-bit byte offset from the base of the device
        from which to start the read.

    MinimumBytes - Supplies the minimum number of bytes to be read.

    ExtendedStatus - Variable to receive extended status information about
        any I/O errors that occurred.

    Buffer - Variable to receive a pointer to the allocated buffer containing
        the bytes read.

Return Value:

    The function value is TRUE if the bytes were read, otherwise FALSE.