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[NTOSKRNL]

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Implemented FstubFixupEfiPartition():
Purpose is to let ReactOS handle realistic partitions length in case of an EFI/GPT protective MBR.
Indeed, when formatting a disk to GPT, you add a protective MBR that contains a fake partition entry, with type 0xEE having the following property: its size is set to maximum allocatable size in MBR.
In that case, if disk is small, you may go beyond disk size.
This is why a fix to partition length may be needed when re-reading partition entry.
This is the way ReactOS creates protective MBR.
You may find some more information here: http://msdn.microsoft.com/en-us/windows/hardware/gg463525

Fixed xHalIoReadPartitionTable():
- Allocate a buffer that has the proper size (instead of allocating a buffer which is too big). Especially since this leads to partial init only some lines after.
- Remove redundant & useless affectation.
- Check/fix 0xEE partition length in case of an EFI/GPT protective MBR (see upper point).

svn path=/trunk/; revision=51002
This commit is contained in:
Pierre Schweitzer 2011-03-09 10:33:13 +00:00
parent b2832e17fc
commit c6d8f7de70
1 changed files with 29 additions and 4 deletions
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33
reactos/ntoskrnl/fstub/disksup.c
View file

@ -24,6 +24,8 @@ const WCHAR DiskMountString[] = L"\\DosDevices\\%C:";
#define PARTITION_MAGIC 0xaa55
#define EFI_PMBR_OSTYPE_EFI 0xEE
#include <pshpack1.h>
typedef struct _REG_DISK_MOUNT_INFO
@ -1358,6 +1360,24 @@ xHalExamineMBR(IN PDEVICE_OBJECT DeviceObject,
}
}
VOID
NTAPI
FstubFixupEfiPartition(IN PPARTITION_DESCRIPTOR PartitionDescriptor,
IN ULONGLONG MaxOffset)
{
ULONG PartitionLength;
PAGED_CODE();
/* Compute partition length (according to MBR entry) */
PartitionLength = PartitionDescriptor->StartingSectorLsb0 + PartitionDescriptor->PartitionLengthLsb0;
/* In case the partition length goes beyond disk size... */
if (PartitionLength > MaxOffset)
{
/* Resize partition to its maximum real length */
PartitionDescriptor->PartitionLengthLsb0 = MaxOffset - PartitionDescriptor->StartingSectorLsb0;
}
}
NTSTATUS
FASTCALL
xHalIoReadPartitionTable(IN PDEVICE_OBJECT DeviceObject,
@ -1425,7 +1445,7 @@ xHalIoReadPartitionTable(IN PDEVICE_OBJECT DeviceObject,
MaxOffset, MaxSector);
/* Allocate our buffer */
Buffer = ExAllocatePoolWithTag(NonPagedPool, PAGE_SIZE, TAG_FILE_SYSTEM);
Buffer = ExAllocatePoolWithTag(NonPagedPool, InputSize, TAG_FILE_SYSTEM);
if (!Buffer)
{
/* Fail, free the input buffer */
@ -1503,9 +1523,6 @@ xHalIoReadPartitionTable(IN PDEVICE_OBJECT DeviceObject,
PartitionDescriptor = (PPARTITION_DESCRIPTOR)
&(((PUSHORT)Buffer)[PARTITION_TABLE_OFFSET]);
/* Get the partition type */
PartitionType = PartitionDescriptor->PartitionType;
/* Start looping partitions */
j++;
DPRINT("FSTUB: Partition Table %d:\n", j);
@ -1524,6 +1541,14 @@ xHalIoReadPartitionTable(IN PDEVICE_OBJECT DeviceObject,
GET_STARTING_SECTOR(PartitionDescriptor),
GET_PARTITION_LENGTH(PartitionDescriptor));
/* Check whether we're facing a protective MBR */
if (PartitionType == EFI_PMBR_OSTYPE_EFI)
{
/* Partition length might be bigger than disk size */
FstubFixupEfiPartition(PartitionDescriptor,
MaxOffset);
}
/* Make sure that the partition is valid, unless it's the first */
if (!(HalpIsValidPartitionEntry(PartitionDescriptor,
MaxOffset,