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audk/MdeModulePkg/Universal/Disk/PartitionDxe/Mbr.c

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/** @file
Decode a hard disk partitioned with the legacy MBR found on most PC's
MBR - Master Boot Record is in the first sector of a partitioned hard disk.
The MBR supports four partitions per disk. The MBR also contains legacy
code that is not run on an EFI system. The legacy code reads the
first sector of the active partition into memory and
BPB - BIOS Parameter Block is in the first sector of a FAT file system.
The BPB contains information about the FAT file system. The BPB is
always on the first sector of a media. The first sector also contains
the legacy boot strap code.
Copyright (c) 2014, Hewlett-Packard Development Company, L.P.<BR>
Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include "Partition.h"
/**
Test to see if the Mbr buffer is a valid MBR.
@param Mbr Parent Handle.
@param LastLba Last Lba address on the device.
@retval TRUE Mbr is a Valid MBR.
@retval FALSE Mbr is not a Valid MBR.
**/
BOOLEAN
PartitionValidMbr (
IN MASTER_BOOT_RECORD *Mbr,
IN EFI_LBA LastLba
)
{
UINT32 StartingLBA;
UINT32 EndingLBA;
UINT32 NewEndingLBA;
INTN Index1;
INTN Index2;
BOOLEAN MbrValid;
if (Mbr->Signature != MBR_SIGNATURE) {
return FALSE;
}
//
// The BPB also has this signature, so it can not be used alone.
//
MbrValid = FALSE;
for (Index1 = 0; Index1 < MAX_MBR_PARTITIONS; Index1++) {
if (Mbr->Partition[Index1].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) == 0) {
continue;
}
MbrValid = TRUE;
StartingLBA = UNPACK_UINT32 (Mbr->Partition[Index1].StartingLBA);
EndingLBA = StartingLBA + UNPACK_UINT32 (Mbr->Partition[Index1].SizeInLBA) - 1;
if (EndingLBA > LastLba) {
//
// Compatibility Errata:
// Some systems try to hide drive space with their INT 13h driver
// This does not hide space from the OS driver. This means the MBR
// that gets created from DOS is smaller than the MBR created from
// a real OS (NT & Win98). This leads to BlockIo->LastBlock being
// wrong on some systems FDISKed by the OS.
//
// return FALSE since no block devices on a system are implemented
// with INT 13h
//
DEBUG((EFI_D_INFO, "PartitionValidMbr: Bad MBR partition size EndingLBA(%1x) > LastLBA(%1x)\n", EndingLBA, LastLba));
return FALSE;
}
for (Index2 = Index1 + 1; Index2 < MAX_MBR_PARTITIONS; Index2++) {
if (Mbr->Partition[Index2].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) == 0) {
continue;
}
NewEndingLBA = UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) + UNPACK_UINT32 (Mbr->Partition[Index2].SizeInLBA) - 1;
if (NewEndingLBA >= StartingLBA && UNPACK_UINT32 (Mbr->Partition[Index2].StartingLBA) <= EndingLBA) {
//
// This region overlaps with the Index1'th region
//
return FALSE;
}
}
}
//
// None of the regions overlapped so MBR is O.K.
//
return MbrValid;
}
/**
Install child handles if the Handle supports MBR format.
@param[in] This Calling context.
@param[in] Handle Parent Handle.
@param[in] DiskIo Parent DiskIo interface.
@param[in] DiskIo2 Parent DiskIo2 interface.
@param[in] BlockIo Parent BlockIo interface.
@param[in] BlockIo2 Parent BlockIo2 interface.
@param[in] DevicePath Parent Device Path.
@retval EFI_SUCCESS A child handle was added.
@retval EFI_MEDIA_CHANGED Media change was detected.
@retval Others MBR partition was not found.
**/
EFI_STATUS
PartitionInstallMbrChildHandles (
IN EFI_DRIVER_BINDING_PROTOCOL *This,
IN EFI_HANDLE Handle,
IN EFI_DISK_IO_PROTOCOL *DiskIo,
IN EFI_DISK_IO2_PROTOCOL *DiskIo2,
IN EFI_BLOCK_IO_PROTOCOL *BlockIo,
IN EFI_BLOCK_IO2_PROTOCOL *BlockIo2,
IN EFI_DEVICE_PATH_PROTOCOL *DevicePath
)
{
EFI_STATUS Status;
MASTER_BOOT_RECORD *Mbr;
UINT32 ExtMbrStartingLba;
UINTN Index;
HARDDRIVE_DEVICE_PATH HdDev;
HARDDRIVE_DEVICE_PATH ParentHdDev;
EFI_STATUS Found;
UINT32 PartitionNumber;
EFI_DEVICE_PATH_PROTOCOL *DevicePathNode;
EFI_DEVICE_PATH_PROTOCOL *LastDevicePathNode;
UINT32 BlockSize;
UINT32 MediaId;
EFI_LBA LastBlock;
Found = EFI_NOT_FOUND;
BlockSize = BlockIo->Media->BlockSize;
MediaId = BlockIo->Media->MediaId;
LastBlock = BlockIo->Media->LastBlock;
Mbr = AllocatePool (BlockSize);
if (Mbr == NULL) {
return Found;
}
Status = DiskIo->ReadDisk (
DiskIo,
MediaId,
0,
BlockSize,
Mbr
);
if (EFI_ERROR (Status)) {
Found = Status;
goto Done;
}
if (!PartitionValidMbr (Mbr, LastBlock)) {
goto Done;
}
//
// We have a valid mbr - add each partition
//
//
// Get starting and ending LBA of the parent block device.
//
LastDevicePathNode = NULL;
ZeroMem (&ParentHdDev, sizeof (ParentHdDev));
DevicePathNode = DevicePath;
while (!IsDevicePathEnd (DevicePathNode)) {
LastDevicePathNode = DevicePathNode;
DevicePathNode = NextDevicePathNode (DevicePathNode);
}
if (LastDevicePathNode != NULL) {
if (DevicePathType (LastDevicePathNode) == MEDIA_DEVICE_PATH &&
DevicePathSubType (LastDevicePathNode) == MEDIA_HARDDRIVE_DP
) {
CopyMem (&ParentHdDev, LastDevicePathNode, sizeof (ParentHdDev));
} else {
LastDevicePathNode = NULL;
}
}
PartitionNumber = 1;
ZeroMem (&HdDev, sizeof (HdDev));
HdDev.Header.Type = MEDIA_DEVICE_PATH;
HdDev.Header.SubType = MEDIA_HARDDRIVE_DP;
SetDevicePathNodeLength (&HdDev.Header, sizeof (HdDev));
HdDev.MBRType = MBR_TYPE_PCAT;
HdDev.SignatureType = SIGNATURE_TYPE_MBR;
if (LastDevicePathNode == NULL) {
//
// This is a MBR, add each partition
//
for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
if (Mbr->Partition[Index].OSIndicator == 0x00 || UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA) == 0) {
//
// Don't use null MBR entries
//
continue;
}
if (Mbr->Partition[Index].OSIndicator == PMBR_GPT_PARTITION) {
//
// This is the guard MBR for the GPT. If you ever see a GPT disk with zero partitions you can get here.
// We can not produce an MBR BlockIo for this device as the MBR spans the GPT headers. So formating
// this BlockIo would corrupt the GPT structures and require a recovery that would corrupt the format
// that corrupted the GPT partition.
//
continue;
}
HdDev.PartitionNumber = PartitionNumber ++;
HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[Index].StartingLBA);
HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[Index].SizeInLBA);
CopyMem (HdDev.Signature, &(Mbr->UniqueMbrSignature[0]), sizeof (Mbr->UniqueMbrSignature));
Status = PartitionInstallChildHandle (
This,
Handle,
DiskIo,
DiskIo2,
BlockIo,
BlockIo2,
DevicePath,
(EFI_DEVICE_PATH_PROTOCOL *) &HdDev,
HdDev.PartitionStart,
HdDev.PartitionStart + HdDev.PartitionSize - 1,
MBR_SIZE,
(BOOLEAN) (Mbr->Partition[Index].OSIndicator == EFI_PARTITION)
);
if (!EFI_ERROR (Status)) {
Found = EFI_SUCCESS;
}
}
} else {
//
// It's an extended partition. Follow the extended partition
// chain to get all the logical drives
//
ExtMbrStartingLba = 0;
do {
Status = DiskIo->ReadDisk (
DiskIo,
MediaId,
MultU64x32 (ExtMbrStartingLba, BlockSize),
BlockSize,
Mbr
);
if (EFI_ERROR (Status)) {
Found = Status;
goto Done;
}
if (UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA) == 0) {
break;
}
if ((Mbr->Partition[0].OSIndicator == EXTENDED_DOS_PARTITION) ||
(Mbr->Partition[0].OSIndicator == EXTENDED_WINDOWS_PARTITION)) {
ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA);
continue;
}
HdDev.PartitionNumber = PartitionNumber ++;
HdDev.PartitionStart = UNPACK_UINT32 (Mbr->Partition[0].StartingLBA) + ExtMbrStartingLba + ParentHdDev.PartitionStart;
HdDev.PartitionSize = UNPACK_UINT32 (Mbr->Partition[0].SizeInLBA);
if ((HdDev.PartitionStart + HdDev.PartitionSize - 1 >= ParentHdDev.PartitionStart + ParentHdDev.PartitionSize) ||
(HdDev.PartitionStart <= ParentHdDev.PartitionStart)) {
break;
}
//
// The signature in EBR(Extended Boot Record) should always be 0.
//
*((UINT32 *) &HdDev.Signature[0]) = 0;
Status = PartitionInstallChildHandle (
This,
Handle,
DiskIo,
DiskIo2,
BlockIo,
BlockIo2,
DevicePath,
(EFI_DEVICE_PATH_PROTOCOL *) &HdDev,
HdDev.PartitionStart - ParentHdDev.PartitionStart,
HdDev.PartitionStart - ParentHdDev.PartitionStart + HdDev.PartitionSize - 1,
MBR_SIZE,
(BOOLEAN) (Mbr->Partition[0].OSIndicator == EFI_PARTITION)
);
if (!EFI_ERROR (Status)) {
Found = EFI_SUCCESS;
}
if ((Mbr->Partition[1].OSIndicator != EXTENDED_DOS_PARTITION) &&
(Mbr->Partition[1].OSIndicator != EXTENDED_WINDOWS_PARTITION)
) {
break;
}
ExtMbrStartingLba = UNPACK_UINT32 (Mbr->Partition[1].StartingLBA);
//
// Don't allow partition to be self referencing
//
if (ExtMbrStartingLba == 0) {
break;
}
} while (ExtMbrStartingLba < ParentHdDev.PartitionSize);
}
Done:
FreePool (Mbr);
return Found;
}
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