Author: pschweitzer
Date: Wed Mar 9 10:33:13 2011
New Revision: 51002
URL: http://svn.reactos.org/svn/reactos?rev=51002&view=rev
Log:
[NTOSKRNL]
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).
Modified:
trunk/reactos/ntoskrnl/fstub/disksup.c
Modified: trunk/reactos/ntoskrnl/fstub/disksup.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/fstub/disksup.c?rev=51002&r1=51001&r2=51002&view=diff
==============================================================================
--- trunk/reactos/ntoskrnl/fstub/disksup.c [iso-8859-1] (original)
+++ trunk/reactos/ntoskrnl/fstub/disksup.c [iso-8859-1] Wed Mar 9 10:33:13 2011
@@ -23,6 +23,8 @@
#define AUTO_DRIVE MAXULONG
#define PARTITION_MAGIC 0xaa55
+
+#define EFI_PMBR_OSTYPE_EFI 0xEE
#include <pshpack1.h>
@@ -1355,6 +1357,24 @@
ASSERT(PartitionDescriptor->PartitionType == 0x55);
}
}
+ }
+}
+
+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;
}
}
@@ -1425,7 +1445,7 @@
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 @@
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);
@@ -1523,6 +1540,14 @@
DPRINT("\tOffset %#08lx for %#08lx Sectors\n",
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,
