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/** @file
Routines supporting partition discovery and
logical device reading
Copyright (c) 2006 - 2019, 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 <IndustryStandard/Mbr.h>
#include "FatLitePeim.h"
/**
Test to see if the Mbr buffer is a valid MBR
@param[in] Mbr Parent Handle
@param[in] 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_PEI_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) {
//
// Compatability Errata:
// Some systems try to hide drive space with thier 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 Because no block devices on a system are implemented
// with INT 13h
//
return FALSE;
}
for (Index2 = Index1 + 1; Index2 < MAX_MBR_PARTITIONS; Index2++) {
if (Mbr->Partition[Index2].OSIndicator == 0x00 || UNPACK_INT32 (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;
}
}
}
//
// Non of the regions overlapped so MBR is O.K.
//
return MbrValid;
}
/**
This function finds Mbr partitions. Main algorithm
is ported from DXE partition driver.
@param[in] PrivateData The global memory map
@param[in] ParentBlockDevNo The parent block device
@retval TRUE New partitions are detected and logical block devices
are added to block device array
@retval FALSE No new partitions are added
**/
BOOLEAN
FatFindMbrPartitions (
IN PEI_FAT_PRIVATE_DATA *PrivateData,
IN UINTN ParentBlockDevNo
)
{
EFI_STATUS Status;
MASTER_BOOT_RECORD *Mbr;
UINTN Index;
BOOLEAN Found;
PEI_FAT_BLOCK_DEVICE *ParentBlockDev;
PEI_FAT_BLOCK_DEVICE *BlockDev;
if (ParentBlockDevNo > PEI_FAT_MAX_BLOCK_DEVICE - 1) {
return FALSE;
}
ParentBlockDev = &(PrivateData->BlockDevice[ParentBlockDevNo]);
if (ParentBlockDev->BlockSize > PEI_FAT_MAX_BLOCK_SIZE) {
DEBUG((DEBUG_ERROR, "Device BlockSize %x exceeds FAT_MAX_BLOCK_SIZE\n", ParentBlockDev->BlockSize));
return FALSE;
}
Found = FALSE;
Mbr = (MASTER_BOOT_RECORD *) PrivateData->BlockData;
Status = FatReadBlock (
PrivateData,
ParentBlockDevNo,
0,
ParentBlockDev->BlockSize,
Mbr
);
if (EFI_ERROR (Status) || !PartitionValidMbr (Mbr, ParentBlockDev->LastBlock)) {
goto Done;
}
//
// We have a valid mbr - add each partition
//
for (Index = 0; Index < MAX_MBR_PARTITIONS; Index++) {
if (Mbr->Partition[Index].OSIndicator == 0x00 || UNPACK_INT32 (Mbr->Partition[Index].SizeInLBA) == 0) {
//
// Don't use null MBR entries
//
continue;
}
//
// Register this partition
//
if (PrivateData->BlockDeviceCount < PEI_FAT_MAX_BLOCK_DEVICE) {
Found = TRUE;
BlockDev = &(PrivateData->BlockDevice[PrivateData->BlockDeviceCount]);
BlockDev->BlockSize = MBR_SIZE;
BlockDev->LastBlock = UNPACK_INT32 (Mbr->Partition[Index].SizeInLBA) - 1;
BlockDev->IoAlign = ParentBlockDev->IoAlign;
BlockDev->Logical = TRUE;
BlockDev->PartitionChecked = FALSE;
BlockDev->StartingPos = MultU64x32 (
UNPACK_INT32 (Mbr->Partition[Index].StartingLBA),
ParentBlockDev->BlockSize
);
BlockDev->ParentDevNo = ParentBlockDevNo;
PrivateData->BlockDeviceCount++;
}
}
Done:
ParentBlockDev->PartitionChecked = TRUE;
return Found;
}
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