NTSTATUS
FASTCALL
IoReadPartitionTable(
  IN  PDEVICE_OBJECT DeviceObject,
  IN  ULONG SectorSize,
  IN  BOOLEAN ReturnRecognizedPartitions,
  OUT struct _DRIVE_LAYOUT_INFORMATION **PartitionBuffer
  );

Routine Description:

    This routine walks the disk reading the partition tables and creates
    an entry in the partition list buffer for each partition.

    The algorithm used by this routine is two-fold:

        1)  Read each partition table and for each valid, recognized
            partition found, to build a descriptor in a partition list.
            Extended partitions are located in order to find other
            partition tables, but no descriptors are built for these.
            The partition list is built in nonpaged pool that is allocated
            by this routine.  It is the caller's responsibility to free
            this pool after it has gathered the appropriate information
            from the list.

        2)  Read each partition table and for each and every entry, build
            a descriptor in the partition list.  Extended partitions are
            located to find each partition table on the disk, and entries
            are built for these as well.  The partition list is build in
            nonpaged pool that is allocated by this routine.  It is the
            caller's responsibility to free this pool after it has copied
            the information back to its caller.

    The first algorithm is used when the ReturnRecognizedPartitions flag
    is set.  This is used to determine how many partition device objects
    the device driver is to create, and where each lives on the drive.

    The second algorithm is used when the ReturnRecognizedPartitions flag
    is clear.  This is used to find all of the partition tables and their
    entries for a utility such as fdisk, that would like to revamp where
    the partitions live.

Arguments:

    DeviceObject - Pointer to device object for this disk.

    SectorSize - Sector size on the device.

    ReturnRecognizedPartitions - A flag indicated whether only recognized
        partition descriptors are to be returned, or whether all partition
        entries are to be returned.

    PartitionBuffer - Pointer to the pointer of the buffer in which the list
        of partition will be stored.

Return Value:

    The functional value is STATUS_SUCCESS if at least one sector table was
    read.

Notes:

    It is the responsibility of the caller to deallocate the partition list
    buffer allocated by this routine.