fstubex.c

Go to the documentation of this file.

/*
* PROJECT:         ReactOS Kernel
* LICENSE:         GPL - See COPYING in the top level directory
* FILE:            ntoskrnl/fstub/fstubex.c
* PURPOSE:         Extended FSTUB Routines (not linked to HAL)
* PROGRAMMERS:     Pierre Schweitzer (pierre.schweitzer@reactos.org)
*/

/* INCLUDES ******************************************************************/

#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>

/* PRIVATE FUNCTIONS *********************************************************/

typedef struct _DISK_INFORMATION
{
    PDEVICE_OBJECT DeviceObject;
    ULONG SectorSize;
    DISK_GEOMETRY_EX DiskGeometry;
    PUSHORT Buffer;
    ULONGLONG SectorCount;
} DISK_INFORMATION, *PDISK_INFORMATION;

#include <pshpack1.h>
typedef struct _EFI_PARTITION_HEADER
{
    ULONGLONG Signature;         // 0
    ULONG Revision;              // 8
    ULONG HeaderSize;            // 12
    ULONG HeaderCRC32;           // 16
    ULONG Reserved;              // 20
    ULONGLONG MyLBA;             // 24
    ULONGLONG AlternateLBA;      // 32
    ULONGLONG FirstUsableLBA;    // 40
    ULONGLONG LastUsableLBA;     // 48
    GUID DiskGUID;               // 56
    ULONGLONG PartitionEntryLBA; // 72
    ULONG NumberOfEntries;       // 80
    ULONG SizeOfPartitionEntry;  // 84
    ULONG PartitionEntryCRC32;   // 88
} EFI_PARTITION_HEADER, *PEFI_PARTITION_HEADER;
#include <poppack.h>

typedef struct _EFI_PARTITION_ENTRY
{
    GUID PartitionType;    // 0
    GUID UniquePartition;  // 16
    ULONGLONG StartingLBA; // 32
    ULONGLONG EndingLBA;   // 40
    ULONGLONG Attributes;  // 48
    WCHAR Name[0x24];      // 56
} EFI_PARTITION_ENTRY, *PEFI_PARTITION_ENTRY;

typedef struct _PARTITION_TABLE_ENTRY
{
    UCHAR BootIndicator;
    UCHAR StartHead;
    UCHAR StartSector;
    UCHAR StartCylinder;
    UCHAR SystemIndicator;
    UCHAR EndHead;
    UCHAR EndSector;
    UCHAR EndCylinder;
    ULONG SectorCountBeforePartition;
    ULONG PartitionSectorCount;
} PARTITION_TABLE_ENTRY, *PPARTITION_TABLE_ENTRY;

typedef struct _MASTER_BOOT_RECORD
{
    UCHAR MasterBootRecordCodeAndData[0x1B8]; // 0
    ULONG Signature;                          // 440
    USHORT Reserved;                          // 444
    PARTITION_TABLE_ENTRY PartitionTable[4];  // 446
    USHORT MasterBootRecordMagic;             // 510
} MASTER_BOOT_RECORD, *PMASTER_BOOT_RECORD;

/* Tag for Fstub allocations */
#define TAG_FSTUB 'BtsF'
/* Partition entry size (bytes) - FIXME: It's hardcoded as Microsoft does, but according to specs, it shouldn't be */
#define PARTITION_ENTRY_SIZE 128
/* Defines "EFI PART" */
#define EFI_HEADER_SIGNATURE  0x5452415020494645ULL
/* Defines version 1.0 */
#define EFI_HEADER_REVISION_1 0x00010000
/* Defines system type for MBR showing that a GPT is following */ 
#define EFI_PMBR_OSTYPE_EFI 0xEE

#define IS_VALID_DISK_INFO(Disk) \
  (Disk)               &&        \
  (Disk->DeviceObject) &&        \
  (Disk->SectorSize)   &&        \
  (Disk->Buffer)       &&        \
  (Disk->SectorCount)

VOID
NTAPI
FstubDbgPrintPartitionEx(IN PPARTITION_INFORMATION_EX PartitionEntry,
                         IN ULONG PartitionNumber
);

NTSTATUS
NTAPI
FstubDetectPartitionStyle(IN PDISK_INFORMATION Disk,
                          IN PARTITION_STYLE * PartitionStyle
);

VOID
NTAPI
FstubFreeDiskInformation(IN PDISK_INFORMATION DiskBuffer
);

NTSTATUS
NTAPI
FstubGetDiskGeometry(IN PDEVICE_OBJECT DeviceObject,
                     OUT PDISK_GEOMETRY_EX Geometry
);

NTSTATUS
NTAPI
FstubReadSector(IN PDEVICE_OBJECT DeviceObject,
                IN ULONG SectorSize,
                IN ULONGLONG StartingSector OPTIONAL,
                OUT PUSHORT Buffer
);

NTSTATUS
NTAPI
FstubWriteBootSectorEFI(IN PDISK_INFORMATION Disk
);

NTSTATUS
NTAPI
FstubWritePartitionTableEFI(IN PDISK_INFORMATION Disk,
                            IN GUID DiskGUID,
                            IN ULONG MaxPartitionCount,
                            IN ULONGLONG FirstUsableLBA,
                            IN ULONGLONG LastUsableLBA,
                            IN BOOLEAN WriteBackupTable,
                            IN ULONG PartitionCount,
                            IN PPARTITION_INFORMATION_EX PartitionEntries OPTIONAL
);

NTSTATUS
NTAPI
FstubWriteSector(IN PDEVICE_OBJECT DeviceObject,
                 IN ULONG SectorSize,
                 IN ULONGLONG StartingSector OPTIONAL,
                 IN PUSHORT Buffer
);

VOID
NTAPI
FstubAdjustPartitionCount(IN ULONG SectorSize,
                          IN OUT PULONG PartitionCount)
{
    ULONG Count;
    PAGED_CODE();

    ASSERT(SectorSize);
    ASSERT(PartitionCount);

    /* Get partition count */
    Count = *PartitionCount;
    /* We need at least 128 entries */
    if (Count < 128)
    {
        Count = 128;
    }

    /* Then, ensure that we will have a round value,
     * ie, all sectors will be full of entries
     * There won't be lonely entries
     */
    Count = (Count * PARTITION_ENTRY_SIZE) / SectorSize;
    Count = (Count * SectorSize) / PARTITION_ENTRY_SIZE;
    ASSERT(*PartitionCount <= Count);
    /* Return result */
    *PartitionCount = Count;

    /* One more sanity check */
    if (SectorSize == 512)
    {
        ASSERT(Count % 4 == 0);
    }
}

NTSTATUS
NTAPI
FstubAllocateDiskInformation(IN PDEVICE_OBJECT DeviceObject,
                             OUT PDISK_INFORMATION * DiskBuffer,
                             PDISK_GEOMETRY_EX DiskGeometry OPTIONAL)
{
    NTSTATUS Status;
    PDISK_INFORMATION DiskInformation;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(DiskBuffer);

    /* Allocate internal structure */
    DiskInformation = ExAllocatePoolWithTag(NonPagedPool, sizeof(DISK_INFORMATION), TAG_FSTUB);
    if (!DiskInformation)
    {
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* If caller don't pass needed information, let's get them */
    if (!DiskGeometry)
    {
        Status = FstubGetDiskGeometry(DeviceObject, &(DiskInformation->DiskGeometry));
        if (!NT_SUCCESS(Status))
        {
            ExFreePoolWithTag(DiskInformation, TAG_FSTUB);
            return Status;
        }
    }
    else
    {
        DiskInformation->DiskGeometry = *DiskGeometry;
    }

    /* Ensure read/received information are correct */
    if (DiskInformation->DiskGeometry.Geometry.BytesPerSector == 0 ||
        DiskInformation->DiskGeometry.DiskSize.QuadPart == 0)
    {
        ExFreePoolWithTag(DiskInformation, TAG_FSTUB);
        return STATUS_DEVICE_NOT_READY;
    }

    /* Store vital information as well */
    DiskInformation->DeviceObject = DeviceObject;
    DiskInformation->SectorSize = DiskInformation->DiskGeometry.Geometry.BytesPerSector;
    DiskInformation->SectorCount = DiskInformation->DiskGeometry.DiskSize.QuadPart / DiskInformation->SectorSize;

    /* Finally, allocate the buffer that will be used for different read */
    DiskInformation->Buffer = ExAllocatePoolWithTag(NonPagedPoolCacheAligned, DiskInformation->SectorSize, TAG_FSTUB);
    if (!DiskInformation->Buffer)
    {
        ExFreePoolWithTag(DiskInformation, TAG_FSTUB);
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* Return allocated internal structure */
    *DiskBuffer = DiskInformation;

    return STATUS_SUCCESS;
}

PDRIVE_LAYOUT_INFORMATION
NTAPI
FstubConvertExtendedToLayout(IN PDRIVE_LAYOUT_INFORMATION_EX LayoutEx)
{
    ULONG i;
    PDRIVE_LAYOUT_INFORMATION DriveLayout;
    PAGED_CODE();

    ASSERT(LayoutEx);

    /* Check whether we're dealing with MBR partition table */
    if (LayoutEx->PartitionStyle != PARTITION_STYLE_MBR)
    {
        ASSERT(FALSE);
        return NULL;
    }

    /* Allocate needed buffer */
    DriveLayout = ExAllocatePoolWithTag(NonPagedPool,
                                        FIELD_OFFSET(DRIVE_LAYOUT_INFORMATION, PartitionEntry) +
                                        LayoutEx->PartitionCount * sizeof(PARTITION_INFORMATION),
                                        TAG_FSTUB);
    if (!DriveLayout)
    {
        return NULL;
    }

    /* Convert information about partition table */
    DriveLayout->PartitionCount = LayoutEx->PartitionCount;
    DriveLayout->Signature = LayoutEx->Mbr.Signature;

    /* Convert each partition */
    for (i = 0; i < LayoutEx->PartitionCount; i++)
    {
        DriveLayout->PartitionEntry[i].StartingOffset = LayoutEx->PartitionEntry[i].StartingOffset;
        DriveLayout->PartitionEntry[i].PartitionLength = LayoutEx->PartitionEntry[i].PartitionLength;
        DriveLayout->PartitionEntry[i].HiddenSectors = LayoutEx->PartitionEntry[i].Mbr.HiddenSectors;
        DriveLayout->PartitionEntry[i].PartitionNumber = LayoutEx->PartitionEntry[i].PartitionNumber;
        DriveLayout->PartitionEntry[i].PartitionType = LayoutEx->PartitionEntry[i].Mbr.PartitionType;
        DriveLayout->PartitionEntry[i].BootIndicator = LayoutEx->PartitionEntry[i].Mbr.BootIndicator;
        DriveLayout->PartitionEntry[i].RecognizedPartition = LayoutEx->PartitionEntry[i].Mbr.RecognizedPartition;
        DriveLayout->PartitionEntry[i].RewritePartition = LayoutEx->PartitionEntry[i].RewritePartition;
    }

    return DriveLayout;
}

VOID
NTAPI
FstubCopyEntryEFI(OUT PEFI_PARTITION_ENTRY Entry,
                  IN PPARTITION_INFORMATION_EX Partition,
                  ULONG SectorSize)
{
    PAGED_CODE();

    ASSERT(Entry);
    ASSERT(Partition);
    ASSERT(SectorSize);

    /* Just convert data to EFI partition entry type */
    Entry->PartitionType = Partition->Gpt.PartitionType;
    Entry->UniquePartition = Partition->Gpt.PartitionId;
    Entry->StartingLBA = Partition->StartingOffset.QuadPart / SectorSize;
    Entry->EndingLBA = (Partition->StartingOffset.QuadPart + Partition->PartitionLength.QuadPart - 1) / SectorSize;
    Entry->Attributes = Partition->Gpt.Attributes;
    RtlCopyMemory(Entry->Name, Partition->Gpt.Name, sizeof(Entry->Name));
}

NTSTATUS
NTAPI
FstubCreateDiskMBR(IN PDEVICE_OBJECT DeviceObject,
                   IN PCREATE_DISK_MBR DiskInfo)
{
    NTSTATUS Status;
    PDISK_INFORMATION Disk = NULL;
    PMASTER_BOOT_RECORD MasterBootRecord;
    PAGED_CODE();

    ASSERT(DeviceObject);

    /* Allocate internal structure */
    Status = FstubAllocateDiskInformation(DeviceObject, &Disk, 0);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }

    /* Read previous MBR, if any */
    Status = FstubReadSector(Disk->DeviceObject,
                             Disk->SectorSize,
                             0ULL,
                             Disk->Buffer);
    if (!NT_SUCCESS(Status))
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }
    /* Fill the buffer with needed information, we won't overwrite boot code */
    MasterBootRecord = (PMASTER_BOOT_RECORD)Disk->Buffer;
    MasterBootRecord->Signature = DiskInfo->Signature;
    RtlZeroMemory(MasterBootRecord->PartitionTable, sizeof(PARTITION_TABLE_ENTRY) * 4);
    MasterBootRecord->MasterBootRecordMagic = BOOT_RECORD_SIGNATURE;

    /* Finally, write MBR */
    Status = FstubWriteSector(Disk->DeviceObject,
                              Disk->SectorSize,
                              0ULL,
                              Disk->Buffer);

    /* Release internal structure and return */
    FstubFreeDiskInformation(Disk);
    return Status;
}

NTSTATUS
NTAPI
FstubCreateDiskEFI(IN PDEVICE_OBJECT DeviceObject,
                   IN PCREATE_DISK_GPT DiskInfo)
{
    NTSTATUS Status;
    PDISK_INFORMATION Disk = NULL;
    ULONGLONG FirstUsableLBA, LastUsableLBA;
    ULONG MaxPartitionCount, SectorsForPartitions;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(DiskInfo);

    /* Allocate internal structure */
    Status = FstubAllocateDiskInformation(DeviceObject, &Disk, 0);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }
    ASSERT(Disk);

    /* Write legacy MBR */
    Status = FstubWriteBootSectorEFI(Disk);
    if (!NT_SUCCESS(Status))
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }

    /* Get max entries and adjust its number */
    MaxPartitionCount = DiskInfo->MaxPartitionCount;
    FstubAdjustPartitionCount(Disk->SectorSize, &MaxPartitionCount);

    /* Count number of sectors needed to store partitions */
    SectorsForPartitions = (MaxPartitionCount * PARTITION_ENTRY_SIZE) / Disk->SectorSize;
    /* Set first usable LBA: Legacy MBR + GPT header + Partitions entries */
    FirstUsableLBA = SectorsForPartitions + 2;
    /* Set last usable LBA: Last sector - GPT header - Partitions entries */
    LastUsableLBA = Disk->SectorCount - SectorsForPartitions - 1;

    /* First, write primary table */
    Status = FstubWritePartitionTableEFI(Disk,
                                         DiskInfo->DiskId,
                                         MaxPartitionCount,
                                         FirstUsableLBA,
                                         LastUsableLBA,
                                         FALSE,
                                         0,
                                         NULL);
    /* Then, write backup table */
    if (NT_SUCCESS(Status))
    {
        Status = FstubWritePartitionTableEFI(Disk,
                                             DiskInfo->DiskId,
                                             MaxPartitionCount,
                                             FirstUsableLBA,
                                             LastUsableLBA,
                                             TRUE,
                                             0,
                                             NULL);
    }

    /* Release internal structure and return */
    FstubFreeDiskInformation(Disk);
    return Status;
}

NTSTATUS
NTAPI
FstubCreateDiskRaw(IN PDEVICE_OBJECT DeviceObject)
{
    NTSTATUS Status;
    PDISK_INFORMATION Disk = NULL;
    PARTITION_STYLE PartitionStyle;
    PMASTER_BOOT_RECORD MasterBootRecord;
    PAGED_CODE();

    ASSERT(DeviceObject);

    /* Allocate internal structure */
    Status = FstubAllocateDiskInformation(DeviceObject, &Disk, 0);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }

    /* Detect current disk partition style */
    Status = FstubDetectPartitionStyle(Disk, &PartitionStyle);
    if (!NT_SUCCESS(Status))
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }

    /* Read MBR, if any */
    Status = FstubReadSector(Disk->DeviceObject,
                             Disk->SectorSize,
                             0ULL,
                             Disk->Buffer);
    if (!NT_SUCCESS(Status))
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }

    /* Only zero useful stuff */
    MasterBootRecord = (PMASTER_BOOT_RECORD)Disk->Buffer;
    MasterBootRecord->Signature = 0;
    RtlZeroMemory(MasterBootRecord->PartitionTable, sizeof(PARTITION_TABLE_ENTRY));
    MasterBootRecord->MasterBootRecordMagic = 0;

    /* Write back that destroyed MBR */
    Status = FstubWriteSector(Disk->DeviceObject,
                              Disk->SectorSize,
                              0ULL,
                              Disk->Buffer);
    /* If previous style wasn't GPT, we're done here */
    if (PartitionStyle != PARTITION_STYLE_GPT)
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }

    /* Otherwise, we've to zero the two GPT headers */
    RtlZeroMemory(Disk->Buffer, Disk->SectorSize);
    /* Erase primary header */
    Status = FstubWriteSector(Disk->DeviceObject,
                              Disk->SectorSize,
                              1ULL,
                              Disk->Buffer);
    /* In case of success, erase backup header */
    if (NT_SUCCESS(Status))
    {
        Status = FstubWriteSector(Disk->DeviceObject,
                                  Disk->SectorSize,
                                  Disk->SectorCount - 1ULL,
                                  Disk->Buffer);
    }

    /* Release internal structure and return */
    FstubFreeDiskInformation(Disk);
    return Status;
}

PCHAR
NTAPI
FstubDbgGuidToString(IN PGUID Guid,
                     OUT PCHAR String)
{
    sprintf(String,
            "{%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}",
            Guid->Data1,
            Guid->Data2,
            Guid->Data3,
            Guid->Data4[0],
            Guid->Data4[1],
            Guid->Data4[2],
            Guid->Data4[3],
            Guid->Data4[4],
            Guid->Data4[5],
            Guid->Data4[6],
            Guid->Data4[7]);

    return String;
}

VOID
NTAPI
FstubDbgPrintDriveLayoutEx(IN PDRIVE_LAYOUT_INFORMATION_EX DriveLayout)
{
    ULONG i;
    CHAR Guid[38];
    PAGED_CODE();

    DPRINT("FSTUB: DRIVE_LAYOUT_INFORMATION_EX: %p\n", DriveLayout);
    switch (DriveLayout->PartitionStyle)
    {
        case PARTITION_STYLE_MBR:
            if (DriveLayout->PartitionCount % 4 != 0)
            {
                DPRINT("Warning: Partition count isn't a 4-factor: %ld!\n", DriveLayout->PartitionCount);
            }

            DPRINT("Signature: %8.8x\n", DriveLayout->Mbr.Signature);
            for (i = 0; i < DriveLayout->PartitionCount; i++)
            {
                FstubDbgPrintPartitionEx(DriveLayout->PartitionEntry, i);
            }

            break;
        case PARTITION_STYLE_GPT:
            FstubDbgGuidToString(&(DriveLayout->Gpt.DiskId), Guid);
            DPRINT("DiskId: %s\n", Guid);
            DPRINT("StartingUsableOffset: %I64x\n", DriveLayout->Gpt.StartingUsableOffset.QuadPart);
            DPRINT("UsableLength: %I64x\n", DriveLayout->Gpt.UsableLength.QuadPart);
            DPRINT("MaxPartitionCount: %ld\n", DriveLayout->Gpt.MaxPartitionCount);
            for (i = 0; i < DriveLayout->PartitionCount; i++)
            {
                FstubDbgPrintPartitionEx(DriveLayout->PartitionEntry, i);
            }

            break;
        default:
            DPRINT("Unsupported partition style: %ld\n", DriveLayout->PartitionStyle);
    }
}

VOID
NTAPI
FstubDbgPrintPartitionEx(IN PPARTITION_INFORMATION_EX PartitionEntry,
                         IN ULONG PartitionNumber)
{
    CHAR Guid[38];
    PAGED_CODE();

    DPRINT("Printing partition %ld\n", PartitionNumber);

    switch (PartitionEntry[PartitionNumber].PartitionStyle)
    {
        case PARTITION_STYLE_MBR:
            DPRINT("  StartingOffset: %I64x\n", PartitionEntry[PartitionNumber].StartingOffset.QuadPart);
            DPRINT("  PartitionLength: %I64x\n", PartitionEntry[PartitionNumber].PartitionLength.QuadPart);
            DPRINT("  RewritePartition: %d\n", PartitionEntry[PartitionNumber].RewritePartition);
            DPRINT("  PartitionType: %02x\n", PartitionEntry[PartitionNumber].Mbr.PartitionType);
            DPRINT("  BootIndicator: %d\n", PartitionEntry[PartitionNumber].Mbr.BootIndicator);
            DPRINT("  RecognizedPartition: %d\n", PartitionEntry[PartitionNumber].Mbr.RecognizedPartition);
            DPRINT("  HiddenSectors: %ld\n", PartitionEntry[PartitionNumber].Mbr.HiddenSectors);

            break;
        case PARTITION_STYLE_GPT:
            DPRINT("  StartingOffset: %I64x\n", PartitionEntry[PartitionNumber].StartingOffset.QuadPart);
            DPRINT("  PartitionLength: %I64x\n", PartitionEntry[PartitionNumber].PartitionLength.QuadPart);
            DPRINT("  RewritePartition: %d\n", PartitionEntry[PartitionNumber].RewritePartition);
            FstubDbgGuidToString(&(PartitionEntry[PartitionNumber].Gpt.PartitionType), Guid);
            DPRINT("  PartitionType: %s\n", Guid);
            FstubDbgGuidToString(&(PartitionEntry[PartitionNumber].Gpt.PartitionId), Guid);
            DPRINT("  PartitionId: %s\n", Guid);
            DPRINT("  Attributes: %16x\n", PartitionEntry[PartitionNumber].Gpt.Attributes);
            DPRINT("  Name: %ws\n", PartitionEntry[PartitionNumber].Gpt.Name);

            break;
        default:
            DPRINT("  Unsupported partition style: %ld\n", PartitionEntry[PartitionNumber].PartitionStyle);
    }
}

VOID
NTAPI
FstubDbgPrintSetPartitionEx(IN PSET_PARTITION_INFORMATION_EX PartitionEntry,
                            IN ULONG PartitionNumber)
{
    CHAR Guid[38];
    PAGED_CODE();

    DPRINT("FSTUB: SET_PARTITION_INFORMATION_EX: %p\n", PartitionEntry);
    DPRINT("Modifying partition %ld\n", PartitionNumber);
    switch (PartitionEntry->PartitionStyle)
    {
        case PARTITION_STYLE_MBR:
            DPRINT("  PartitionType: %02x\n", PartitionEntry->Mbr.PartitionType);

            break;
        case PARTITION_STYLE_GPT:
            FstubDbgGuidToString(&(PartitionEntry->Gpt.PartitionType), Guid);
            DPRINT("  PartitionType: %s\n", Guid);
            FstubDbgGuidToString(&(PartitionEntry->Gpt.PartitionId), Guid);
            DPRINT("  PartitionId: %s\n", Guid);
            DPRINT("  Attributes: %16x\n", PartitionEntry->Gpt.Attributes);
            DPRINT("  Name: %ws\n", PartitionEntry->Gpt.Name);

            break;
        default:
            DPRINT("  Unsupported partition style: %ld\n", PartitionEntry[PartitionNumber].PartitionStyle);
    }
}

NTSTATUS
NTAPI
FstubDetectPartitionStyle(IN PDISK_INFORMATION Disk,
                          IN PARTITION_STYLE * PartitionStyle)
{
    NTSTATUS Status;
    PPARTITION_DESCRIPTOR PartitionDescriptor;
    PAGED_CODE();

    ASSERT(IS_VALID_DISK_INFO(Disk));
    ASSERT(PartitionStyle);

    /* Read disk first sector */
    Status = FstubReadSector(Disk->DeviceObject,
                             Disk->SectorSize,
                             0,
                             Disk->Buffer);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }

    /* Get the partition descriptor array */
    PartitionDescriptor = (PPARTITION_DESCRIPTOR)
                          &(Disk->Buffer[PARTITION_TABLE_OFFSET]);
    /* If we have not the 0xAA55 then it's raw partition */
    if (Disk->Buffer[BOOT_SIGNATURE_OFFSET] != BOOT_RECORD_SIGNATURE)
    {
        *PartitionStyle = PARTITION_STYLE_RAW;
    }
    /* Check partitions types: if first is 0xEE and all the others 0, we have GPT */
    else if (PartitionDescriptor[0].PartitionType == EFI_PMBR_OSTYPE_EFI &&
             PartitionDescriptor[1].PartitionType == 0 &&
             PartitionDescriptor[2].PartitionType == 0 &&
             PartitionDescriptor[3].PartitionType == 0)
    {
        *PartitionStyle = PARTITION_STYLE_GPT;
    }
    /* Otherwise, partition table is in MBR */
    else
    {
        *PartitionStyle = PARTITION_STYLE_MBR;
    }

    return STATUS_SUCCESS;
}

VOID
NTAPI
FstubFreeDiskInformation(IN PDISK_INFORMATION DiskBuffer)
{
    if (DiskBuffer)
    {
        if (DiskBuffer->Buffer)
        {
            ExFreePoolWithTag(DiskBuffer->Buffer, TAG_FSTUB);
        }
        ExFreePoolWithTag(DiskBuffer, TAG_FSTUB);
    }
}

NTSTATUS
NTAPI
FstubGetDiskGeometry(IN PDEVICE_OBJECT DeviceObject,
                     OUT PDISK_GEOMETRY_EX Geometry)
{
    PIRP Irp;
    NTSTATUS Status;
    PKEVENT Event = NULL;
    PDISK_GEOMETRY_EX DiskGeometry = NULL;
    PIO_STATUS_BLOCK IoStatusBlock = NULL;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(Geometry);

    /* Allocate needed components */
    DiskGeometry = ExAllocatePoolWithTag(NonPagedPool, sizeof(DISK_GEOMETRY_EX), TAG_FSTUB);
    if (!DiskGeometry)
    {
        Status = STATUS_INSUFFICIENT_RESOURCES;
        goto Cleanup;
    }

    IoStatusBlock = ExAllocatePoolWithTag(NonPagedPool, sizeof(IO_STATUS_BLOCK), TAG_FSTUB);
    if (!IoStatusBlock)
    {
        Status = STATUS_INSUFFICIENT_RESOURCES;
        goto Cleanup;
    }

    Event = ExAllocatePoolWithTag(NonPagedPool, sizeof(KEVENT), TAG_FSTUB);
    if (!Event)
    {
        Status = STATUS_INSUFFICIENT_RESOURCES;
        goto Cleanup;
    }
    /* Initialize the waiting event */
    KeInitializeEvent(Event, NotificationEvent, FALSE);

    /* Build the request to get disk geometry */
    Irp = IoBuildDeviceIoControlRequest(IOCTL_DISK_GET_DRIVE_GEOMETRY_EX,
                                        DeviceObject,
                                        0,
                                        0,
                                        DiskGeometry,
                                        sizeof(DISK_GEOMETRY_EX),
                                        FALSE,
                                        Event,
                                        IoStatusBlock);
    if (!Irp)
    {
        Status = STATUS_INSUFFICIENT_RESOURCES;
        goto Cleanup;
    }

    /* Call the driver and wait for completion if needed */
    Status = IoCallDriver(DeviceObject, Irp);
    if (Status == STATUS_PENDING)
    {
        KeWaitForSingleObject(Event, Executive, KernelMode, FALSE, NULL);
        Status = IoStatusBlock->Status;
    }

    /* In case of a success, return read data */
    if (NT_SUCCESS(Status))
    {
        *Geometry = *DiskGeometry;
    }

Cleanup:
    if (DiskGeometry)
    {
        ExFreePoolWithTag(DiskGeometry, TAG_FSTUB);

        if (NT_SUCCESS(Status))
        {
            ASSERT(Geometry->Geometry.BytesPerSector % PARTITION_ENTRY_SIZE == 0);
        }
    }

    if (IoStatusBlock)
    {
        ExFreePoolWithTag(IoStatusBlock, TAG_FSTUB);
    }

    if (Event)
    {
        ExFreePoolWithTag(Event, TAG_FSTUB);
    }

    return Status;
}

NTSTATUS
NTAPI
FstubReadHeaderEFI(IN PDISK_INFORMATION Disk,
                   IN BOOLEAN ReadBackupTable,
                   PEFI_PARTITION_HEADER HeaderBuffer)
{
    NTSTATUS Status;
    PUCHAR Sector = NULL;
    ULONGLONG StartingSector;
    PEFI_PARTITION_HEADER EFIHeader;
    ULONG i, HeaderCRC32, PreviousCRC32, SectoredPartitionEntriesSize, LonelyPartitions;
    PAGED_CODE();

    ASSERT(Disk);
    ASSERT(IS_VALID_DISK_INFO(Disk));
    ASSERT(HeaderBuffer);

    /* In case we want to read backup table, we read last disk sector */
    if (ReadBackupTable)
    {
        StartingSector = Disk->SectorCount - 1ULL;
    }
    else
    {
        /* Otherwise we start at first sector (as sector 0 is the MBR) */
        StartingSector = 1ULL;
    }

    Status = FstubReadSector(Disk->DeviceObject,
                             Disk->SectorSize,
                             StartingSector,
                             Disk->Buffer);
    if (!NT_SUCCESS(Status))
    {
        DPRINT("EFI::Failed reading header!\n");
        return Status;
    }
    /* Let's use read buffer as EFI_PARTITION_HEADER */
    EFIHeader = (PEFI_PARTITION_HEADER)Disk->Buffer;


    /* First check signature
     * Then, check version (we only support v1)
     * Finally check header size
     */
    if (EFIHeader->Signature != EFI_HEADER_SIGNATURE ||
        EFIHeader->Revision != EFI_HEADER_REVISION_1 ||
        EFIHeader->HeaderSize != sizeof(EFI_PARTITION_HEADER))
    {
        DPRINT("EFI::Wrong signature/version/header size!\n");
        DPRINT("%I64x (expected: %I64x)\n", EFIHeader->Signature, EFI_HEADER_SIGNATURE);
        DPRINT("%03x (expected: %03x)\n", EFIHeader->Revision, EFI_HEADER_REVISION_1);
        DPRINT("%02x (expected: %02x)\n", EFIHeader->HeaderSize, sizeof(EFI_PARTITION_HEADER));
        return STATUS_DISK_CORRUPT_ERROR;
    }

    /* Save current checksum */
    HeaderCRC32 = EFIHeader->HeaderCRC32;
    /* Then zero the one in EFI header. This is needed to compute header checksum */
    EFIHeader->HeaderCRC32 = 0;
    /* Compute header checksum and compare with the one present in partition table */
    if (RtlComputeCrc32(0, (PUCHAR)Disk->Buffer, sizeof(EFI_PARTITION_HEADER)) != HeaderCRC32)
    {
        DPRINT("EFI::Not matching header checksum!\n");
        return STATUS_DISK_CORRUPT_ERROR;
    }
    /* Put back removed checksum in header */
    EFIHeader->HeaderCRC32 = HeaderCRC32;

    /* Check if current LBA is matching with ours */
    if (EFIHeader->MyLBA != StartingSector)
    {
        DPRINT("EFI::Not matching starting sector!\n");
        return STATUS_DISK_CORRUPT_ERROR;
    }

    /* Allocate a buffer to read a sector on the disk */
    Sector = ExAllocatePoolWithTag(NonPagedPool,
                                   Disk->SectorSize,
                                   TAG_FSTUB);
    if (!Sector)
    {
        DPRINT("EFI::Lacking resources!\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* Count how much sectors we'll have to read to read the whole partition table */
    SectoredPartitionEntriesSize = (EFIHeader->NumberOfEntries * PARTITION_ENTRY_SIZE) / Disk->SectorSize;
    /* Compute partition table checksum */
    for (i = 0, PreviousCRC32 = 0; i < SectoredPartitionEntriesSize; i++)
    {
        Status = FstubReadSector(Disk->DeviceObject,
                                 Disk->SectorSize,
                                 EFIHeader->PartitionEntryLBA + i,
                                 (PUSHORT)Sector);
        if (!NT_SUCCESS(Status))
        {
            ExFreePoolWithTag(Sector, TAG_FSTUB);
            DPRINT("EFI::Failed reading sector for partition entry!\n");
            return Status;
        }

        PreviousCRC32 = RtlComputeCrc32(PreviousCRC32, Sector, Disk->SectorSize);
    }

    /* Check whether we have a last sector not full of partitions */
    LonelyPartitions = (EFIHeader->NumberOfEntries * PARTITION_ENTRY_SIZE) % Disk->SectorSize;
    /* In such case, we have to complete checksum computation */
    if (LonelyPartitions != 0)
    {
        /* Read the sector that contains those partitions */
        Status = FstubReadSector(Disk->DeviceObject,
                                 Disk->SectorSize,
                                 EFIHeader->PartitionEntryLBA + i,
                                 (PUSHORT)Sector);
        if (!NT_SUCCESS(Status))
        {
            ExFreePoolWithTag(Sector, TAG_FSTUB);
            DPRINT("EFI::Failed reading sector for partition entry!\n");
            return Status;
        }

        /* Then complete checksum by computing on each partition */
        for (i = 0; i < LonelyPartitions; i++)
        {
            PreviousCRC32 = RtlComputeCrc32(PreviousCRC32, Sector + i * PARTITION_ENTRY_SIZE, PARTITION_ENTRY_SIZE);
        }
    }

    /* Finally, release memory */
    ExFreePoolWithTag(Sector, TAG_FSTUB);

    /* Compare checksums */
    if (PreviousCRC32 == EFIHeader->PartitionEntryCRC32)
    {
        /* In case of a success, return read header */
        *HeaderBuffer = *EFIHeader;
        return STATUS_SUCCESS;
    }
    else
    {
        DPRINT("EFI::Not matching partition table checksum!\n");
        DPRINT("EFI::Expected: %x, received: %x\n", EFIHeader->PartitionEntryCRC32, PreviousCRC32);
        return STATUS_DISK_CORRUPT_ERROR;
    }
}

NTSTATUS
NTAPI
FstubReadPartitionTableEFI(IN PDISK_INFORMATION Disk,
                           IN BOOLEAN ReadBackupTable,
                           OUT struct _DRIVE_LAYOUT_INFORMATION_EX** DriveLayout)
{
    NTSTATUS Status;
    EFI_PARTITION_HEADER EfiHeader;
    ULONGLONG SectorsForPartitions;
    EFI_PARTITION_ENTRY PartitionEntry;
    BOOLEAN UpdatedPartitionTable = FALSE;
    PDRIVE_LAYOUT_INFORMATION_EX DriveLayoutEx = NULL;
    ULONG i, PartitionCount, PartitionIndex, PartitionsPerSector;
    PAGED_CODE();

    ASSERT(Disk);

    /* Zero output */
    *DriveLayout = NULL;

    /* Read EFI header */
    Status = FstubReadHeaderEFI(Disk,
                                ReadBackupTable,
                                &EfiHeader);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }

    /* Allocate a DRIVE_LAYOUT_INFORMATION_EX struct big enough */
    DriveLayoutEx = ExAllocatePoolWithTag(NonPagedPool,
                                          FIELD_OFFSET(DRIVE_LAYOUT_INFORMATION_EX, PartitionEntry) +
                                          EfiHeader.NumberOfEntries * sizeof(PARTITION_INFORMATION_EX),
                                          TAG_FSTUB);
    if (!DriveLayoutEx)
    {
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    if (ReadBackupTable)
    {
        /* If we read backup but if it doesn't match with current geometry */
        if ((Disk->SectorCount - 1ULL) != EfiHeader.AlternateLBA)
        {
            /* We'll update it. First, count number of sectors needed to store partitions */
            SectorsForPartitions = ((ULONGLONG)EfiHeader.NumberOfEntries * PARTITION_ENTRY_SIZE) / Disk->SectorSize;
            /* Then set first usable LBA: Legacy MBR + GPT header + Partitions entries */
            EfiHeader.FirstUsableLBA = SectorsForPartitions + 2;
            /* Then set last usable LBA: Last sector - GPT header - Partitions entries */
            EfiHeader.LastUsableLBA = Disk->SectorCount - SectorsForPartitions - 1;
            /* Inform that we'll rewrite partition table */
            UpdatedPartitionTable = TRUE;
        }
    }

    DriveLayoutEx->PartitionStyle = PARTITION_STYLE_GPT;
    /* Translate LBA -> Offset */
    DriveLayoutEx->Gpt.StartingUsableOffset.QuadPart = EfiHeader.FirstUsableLBA * Disk->SectorSize;
    DriveLayoutEx->Gpt.UsableLength.QuadPart = EfiHeader.LastUsableLBA - EfiHeader.FirstUsableLBA * Disk->SectorSize;
    DriveLayoutEx->Gpt.MaxPartitionCount = EfiHeader.NumberOfEntries;
    DriveLayoutEx->Gpt.DiskId = EfiHeader.DiskGUID;

    /* Count number of partitions per sector */
    PartitionsPerSector = (Disk->SectorSize / PARTITION_ENTRY_SIZE);
    /* Read all partitions and fill in structure */
    for (i = 0, PartitionCount = 0, PartitionIndex = PartitionsPerSector;
         i < EfiHeader.NumberOfEntries;
         i++)
    {
        /* Only read following sector if we finished with previous sector */
        if (PartitionIndex == PartitionsPerSector)
        {
            Status = FstubReadSector(Disk->DeviceObject,
                                     Disk->SectorSize,
                                     EfiHeader.PartitionEntryLBA + (i / PartitionsPerSector),
                                     Disk->Buffer);
            if (!NT_SUCCESS(Status))
            {
                ExFreePoolWithTag(DriveLayoutEx, TAG_FSTUB);
                return Status;
            }

            PartitionIndex = 0;
        }
        /* Read following partition */
        PartitionEntry = ((PEFI_PARTITION_ENTRY)Disk->Buffer)[PartitionIndex];
        PartitionIndex++;

        /* If partition GUID is 00000000-0000-0000-0000-000000000000, then it's unused, skip it */
        if (PartitionEntry.PartitionType.Data1 == 0 &&
            PartitionEntry.PartitionType.Data2 == 0 &&
            PartitionEntry.PartitionType.Data3 == 0 &&
            ((PULONGLONG)PartitionEntry.PartitionType.Data4)[0] == 0)
        {
            continue;
        }

        /* Write data to structure. Don't forget GPT is using sectors, Windows offsets */
        DriveLayoutEx->PartitionEntry[PartitionCount].StartingOffset.QuadPart = PartitionEntry.StartingLBA * Disk->SectorSize;
        DriveLayoutEx->PartitionEntry[PartitionCount].PartitionLength.QuadPart = (PartitionEntry.EndingLBA -
                                                                                  PartitionEntry.StartingLBA + 1) *
                                                                                 Disk->SectorSize;
        /* This number starts from 1 */
        DriveLayoutEx->PartitionEntry[PartitionCount].PartitionNumber = PartitionCount + 1;
        DriveLayoutEx->PartitionEntry[PartitionCount].RewritePartition = FALSE;
        DriveLayoutEx->PartitionEntry[PartitionCount].PartitionStyle = PARTITION_STYLE_GPT;
        DriveLayoutEx->PartitionEntry[PartitionCount].Gpt.PartitionType = PartitionEntry.PartitionType;
        DriveLayoutEx->PartitionEntry[PartitionCount].Gpt.PartitionId = PartitionEntry.UniquePartition;
        DriveLayoutEx->PartitionEntry[PartitionCount].Gpt.Attributes = PartitionEntry.Attributes;
        RtlCopyMemory(DriveLayoutEx->PartitionEntry[PartitionCount].Gpt.Name,
                      PartitionEntry.Name, sizeof(PartitionEntry.Name));

        /* Update partition count */
        PartitionCount++;
    }
    DriveLayoutEx->PartitionCount = PartitionCount;

    /* If we updated partition table using backup table, rewrite partition table */ 
    if (UpdatedPartitionTable)
    {
        IoWritePartitionTableEx(Disk->DeviceObject,
                                DriveLayoutEx);
    }

    /* Finally, return read data */
    *DriveLayout = DriveLayoutEx;

    return Status;
}

NTSTATUS
NTAPI
FstubReadPartitionTableMBR(IN PDISK_INFORMATION Disk,
                           IN BOOLEAN ReturnRecognizedPartitions,
                           OUT struct _DRIVE_LAYOUT_INFORMATION_EX** ReturnedDriveLayout)
{
    ULONG i;
    NTSTATUS Status;
    PDRIVE_LAYOUT_INFORMATION DriveLayout = NULL;
    PDRIVE_LAYOUT_INFORMATION_EX DriveLayoutEx = NULL;
    PAGED_CODE();

    ASSERT(IS_VALID_DISK_INFO(Disk));
    ASSERT(ReturnedDriveLayout);

    /* Zero output */
    *ReturnedDriveLayout = NULL;

    /* Read partition table the old way */
    Status = IoReadPartitionTable(Disk->DeviceObject,
                                  Disk->SectorSize,
                                  ReturnRecognizedPartitions,
                                  &DriveLayout);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }

    /* Allocate a DRIVE_LAYOUT_INFORMATION_EX struct big enough */
    DriveLayoutEx = ExAllocatePoolWithTag(NonPagedPool,
                                          FIELD_OFFSET(DRIVE_LAYOUT_INFORMATION_EX, PartitionEntry) +
                                          DriveLayout->PartitionCount * sizeof(PARTITION_INFORMATION_EX),
                                          TAG_FSTUB);
    if (!DriveLayoutEx)
    {
        /* Let's not leak memory as in Windows 2003 */
        ExFreePool(DriveLayout);
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* Start converting the DRIVE_LAYOUT_INFORMATION structure */
    DriveLayoutEx->PartitionStyle = PARTITION_STYLE_MBR;
    DriveLayoutEx->PartitionCount = DriveLayout->PartitionCount;
    DriveLayoutEx->Mbr.Signature = DriveLayout->Signature;

    /* Convert each found partition */
    for (i = 0; i < DriveLayout->PartitionCount; i++)
    {
        DriveLayoutEx->PartitionEntry[i].PartitionStyle = PARTITION_STYLE_MBR;
        DriveLayoutEx->PartitionEntry[i].StartingOffset = DriveLayout->PartitionEntry[i].StartingOffset;
        DriveLayoutEx->PartitionEntry[i].PartitionLength = DriveLayout->PartitionEntry[i].PartitionLength;
        DriveLayoutEx->PartitionEntry[i].PartitionNumber = DriveLayout->PartitionEntry[i].PartitionNumber;
        DriveLayoutEx->PartitionEntry[i].RewritePartition = DriveLayout->PartitionEntry[i].RewritePartition;
        DriveLayoutEx->PartitionEntry[i].Mbr.PartitionType = DriveLayout->PartitionEntry[i].PartitionType;
        DriveLayoutEx->PartitionEntry[i].Mbr.BootIndicator = DriveLayout->PartitionEntry[i].BootIndicator;
        DriveLayoutEx->PartitionEntry[i].Mbr.RecognizedPartition = DriveLayout->PartitionEntry[i].RecognizedPartition;
        DriveLayoutEx->PartitionEntry[i].Mbr.HiddenSectors = DriveLayout->PartitionEntry[i].HiddenSectors;
    }

    /* Finally, return data and free old structure */
    *ReturnedDriveLayout = DriveLayoutEx;
    ExFreePool(DriveLayout);

    return STATUS_SUCCESS;
}

NTSTATUS
NTAPI
FstubReadSector(IN PDEVICE_OBJECT DeviceObject,
                IN ULONG SectorSize,
                IN ULONGLONG StartingSector OPTIONAL,
                OUT PUSHORT Buffer)
{
    PIRP Irp;
    KEVENT Event;
    NTSTATUS Status;
    LARGE_INTEGER StartingOffset;
    IO_STATUS_BLOCK IoStatusBlock;
    PIO_STACK_LOCATION IoStackLocation;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(Buffer);
    ASSERT(SectorSize);

    /* Compute starting offset */
    StartingOffset.QuadPart = StartingSector * SectorSize;

    /* Initialize waiting event */
    KeInitializeEvent(&Event, NotificationEvent, FALSE);

    /* Prepare IRP */
    Irp = IoBuildSynchronousFsdRequest(IRP_MJ_READ,
                                       DeviceObject,
                                       Buffer,
                                       SectorSize,
                                       &StartingOffset,
                                       &Event,
                                       &IoStatusBlock);
    if (!Irp)
    {
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* Override volume verify */
    IoStackLocation = IoGetNextIrpStackLocation(Irp);
    IoStackLocation->Flags |= SL_OVERRIDE_VERIFY_VOLUME;

    /* Then call driver, and wait for completion if needed */
    Status = IoCallDriver(DeviceObject, Irp);
    if (Status == STATUS_PENDING)
    {
        KeWaitForSingleObject(&Event, Executive, KernelMode, FALSE, NULL);
        Status = IoStatusBlock.Status;
    }

    return Status;
}

NTSTATUS
NTAPI
FstubSetPartitionInformationEFI(IN PDISK_INFORMATION Disk,
                                IN ULONG PartitionNumber,
                                IN SET_PARTITION_INFORMATION_GPT * PartitionInfo)
{
    NTSTATUS Status;
    PDRIVE_LAYOUT_INFORMATION_EX Layout = NULL;
    PAGED_CODE();

    ASSERT(Disk);
    ASSERT(PartitionInfo);

    /* Partition 0 isn't correct (should start at 1) */
    if (PartitionNumber == 0)
    {
        return STATUS_INVALID_PARAMETER;
    }

    /* Read partition table */
    Status = IoReadPartitionTableEx(Disk->DeviceObject, &Layout);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }
    ASSERT(Layout);

    /* If our partition (started at 0 now) is higher than partition count, then, there's an issue */
    if (Layout->PartitionCount <= --PartitionNumber)
    {
        ExFreePool(Layout);
        return STATUS_INVALID_PARAMETER;
    }

    /* Erase actual partition entry data with provided ones */
    Layout->PartitionEntry[PartitionNumber].Gpt.PartitionType = PartitionInfo->PartitionType;
    Layout->PartitionEntry[PartitionNumber].Gpt.PartitionId = PartitionInfo->PartitionId;
    Layout->PartitionEntry[PartitionNumber].Gpt.Attributes = PartitionInfo->Attributes;
    RtlCopyMemory(Layout->PartitionEntry[PartitionNumber].Gpt.Name, PartitionInfo->Name, sizeof(PartitionInfo->Name));

    /* Rewrite the whole partition table to update the modified entry */
    Status = IoWritePartitionTableEx(Disk->DeviceObject, Layout);

    /* Free partition table and return */
    ExFreePool(Layout);
    return Status;
}

NTSTATUS
NTAPI
FstubVerifyPartitionTableEFI(IN PDISK_INFORMATION Disk,
                             IN BOOLEAN FixErrors)
{
    NTSTATUS Status;
    PEFI_PARTITION_HEADER EFIHeader;
    EFI_PARTITION_HEADER ReadEFIHeader;
    BOOLEAN PrimaryValid = FALSE, BackupValid = FALSE;
    PAGED_CODE();

    EFIHeader = ExAllocatePoolWithTag(NonPagedPool, sizeof(EFI_PARTITION_HEADER), TAG_FSTUB);
    if (!EFIHeader)
    {
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    Status = FstubReadHeaderEFI(Disk, FALSE, &ReadEFIHeader);
    if (NT_SUCCESS(Status))
    {
        PrimaryValid = TRUE;
    }

    Status = FstubReadHeaderEFI(Disk, TRUE, &ReadEFIHeader);
    if (NT_SUCCESS(Status))
    {
        BackupValid = TRUE;
    }

    if (!PrimaryValid)
    {
        if (!BackupValid || !FixErrors)
        {
            ExFreePoolWithTag(EFIHeader, TAG_FSTUB);
            return STATUS_DISK_CORRUPT_ERROR;
        }

        DPRINT1("EFI::Partition table fixing not yet supported!\n");
        ExFreePoolWithTag(EFIHeader, TAG_FSTUB);
        return STATUS_NOT_IMPLEMENTED;
    }
    else if (!BackupValid)
    {
        if (!PrimaryValid || !FixErrors)
        {
            ExFreePoolWithTag(EFIHeader, TAG_FSTUB);
            return STATUS_DISK_CORRUPT_ERROR;
        }

        DPRINT1("EFI::Partition table fixing not yet supported!\n");
        ExFreePoolWithTag(EFIHeader, TAG_FSTUB);
        return STATUS_NOT_IMPLEMENTED;
    }
    else
    {
        ExFreePoolWithTag(EFIHeader, TAG_FSTUB);
        return STATUS_SUCCESS;
    }
}

NTSTATUS
NTAPI
FstubWriteBootSectorEFI(IN PDISK_INFORMATION Disk)
{
    NTSTATUS Status;
    ULONG Signature = 0;
    PMASTER_BOOT_RECORD MasterBootRecord;
    PAGED_CODE();

    ASSERT(Disk);
    ASSERT(IS_VALID_DISK_INFO(Disk));

    /* Read if a MBR is already present */
    Status = FstubReadSector(Disk->DeviceObject,
                             Disk->SectorSize,
                             0ULL,
                             Disk->Buffer);
    MasterBootRecord = (PMASTER_BOOT_RECORD)Disk->Buffer;
    /* If one has been found */
    if (NT_SUCCESS(Status) && MasterBootRecord->MasterBootRecordMagic == BOOT_RECORD_SIGNATURE)
    {
        /* Save its signature */
        Signature = MasterBootRecord->Signature;
    }

    /* Reset the MBR */
    RtlZeroMemory(MasterBootRecord, Disk->SectorSize);
    /* Then create a fake MBR matching those purposes:
     * It must have only partition. Type of this partition
     * has to be 0xEE to signal a GPT is following.
     * This partition has to cover the whole disk. To prevent
     * any disk modification by a program that wouldn't
     * understand anything to GPT.
     */
    MasterBootRecord->Signature = Signature;
    MasterBootRecord->PartitionTable[0].StartSector = 2;
    MasterBootRecord->PartitionTable[0].SystemIndicator = EFI_PMBR_OSTYPE_EFI;
    MasterBootRecord->PartitionTable[0].EndHead = 0xFF;
    MasterBootRecord->PartitionTable[0].EndSector = 0xFF;
    MasterBootRecord->PartitionTable[0].EndCylinder = 0xFF;
    MasterBootRecord->PartitionTable[0].SectorCountBeforePartition = 1;
    MasterBootRecord->PartitionTable[0].PartitionSectorCount = 0xFFFFFFFF;
    MasterBootRecord->MasterBootRecordMagic = BOOT_RECORD_SIGNATURE;

    /* Finally, write that MBR */
    return FstubWriteSector(Disk->DeviceObject,
                            Disk->SectorSize,
                            0,
                            Disk->Buffer);
}

NTSTATUS
NTAPI
FstubWriteEntryEFI(IN PDISK_INFORMATION Disk,
                   IN ULONG PartitionsSizeSector,
                   IN ULONG PartitionEntryNumber,
                   IN PEFI_PARTITION_ENTRY PartitionEntry,
                   IN BOOLEAN WriteBackupTable,
                   IN BOOLEAN ForceWrite,
                   OUT PULONG PartitionEntryCRC32 OPTIONAL)
{
    ULONG Offset;
    ULONGLONG FirstEntryLBA;
    NTSTATUS Status = STATUS_SUCCESS;
    PAGED_CODE();

    ASSERT(Disk);
    ASSERT(IS_VALID_DISK_INFO(Disk));

    /* Get the first LBA where the partition table is:
     * On primary table, it's sector 2 (skip MBR & Header)
     * On backup table, it's ante last sector (Header) minus partition table size
     */
    if (!WriteBackupTable)
    {
        FirstEntryLBA = 2ULL;
    }
    else
    {
        FirstEntryLBA = Disk->SectorCount - PartitionsSizeSector - 1;
    }

    /* Copy the entry at the proper place into the buffer
     * That way, we don't erase previous entries
     */
    RtlCopyMemory(Disk->Buffer + (((PartitionEntryNumber * PARTITION_ENTRY_SIZE) % Disk->SectorSize) / sizeof(PUSHORT)),
                  PartitionEntry,
                  sizeof(EFI_PARTITION_ENTRY));
    /* Compute size of buffer */
    Offset = (PartitionEntryNumber * PARTITION_ENTRY_SIZE) % Disk->SectorSize + PARTITION_ENTRY_SIZE;
    ASSERT(Offset <= Disk->SectorSize);

    /* If it's full of partition entries, or if call ask for it, write down the data */
    if (Offset == Disk->SectorSize || ForceWrite)
    {
        /* We will write at first entry LBA + a shift made by already present/written entries */
        Status = FstubWriteSector(Disk->DeviceObject,
                                  Disk->SectorSize,
                                  FirstEntryLBA + ((PartitionEntryNumber * PARTITION_ENTRY_SIZE) / Disk->SectorSize),
                                  Disk->Buffer);
        if (!NT_SUCCESS(Status))
        {
            return Status;
        }
        /* We clean buffer */
        RtlZeroMemory(Disk->Buffer, Disk->SectorSize);
    }

    /* If we have a buffer for CRC32, then compute it */
    if (PartitionEntryCRC32)
    {
        *PartitionEntryCRC32 = RtlComputeCrc32(*PartitionEntryCRC32, (PUCHAR)PartitionEntry, PARTITION_ENTRY_SIZE);
    }

    return Status;
}

NTSTATUS
NTAPI
FstubWriteHeaderEFI(IN PDISK_INFORMATION Disk,
                    IN ULONG PartitionsSizeSector,
                    IN GUID DiskGUID,
                    IN ULONG NumberOfEntries,
                    IN ULONGLONG FirstUsableLBA,
                    IN ULONGLONG LastUsableLBA,
                    IN ULONG PartitionEntryCRC32,
                    IN BOOLEAN WriteBackupTable)
{
    PEFI_PARTITION_HEADER EFIHeader;
    PAGED_CODE();

    ASSERT(Disk);
    ASSERT(IS_VALID_DISK_INFO(Disk));

    /* Let's use read buffer as EFI_PARTITION_HEADER */
    EFIHeader = (PEFI_PARTITION_HEADER)Disk->Buffer;

    /* Complete standard header information */
    EFIHeader->Signature = EFI_HEADER_SIGNATURE;
    EFIHeader->Revision = EFI_HEADER_REVISION_1;
    EFIHeader->HeaderSize = sizeof(EFI_PARTITION_HEADER);
    /* Set no CRC32 checksum at the moment */
    EFIHeader->HeaderCRC32 = 0;
    EFIHeader->Reserved = 0;
    /* Check whether we're writing primary or backup
     * That way, we can ajust LBA setting:
     * Primary is on first sector
     * Backup is on last sector
     */
    if (!WriteBackupTable)
    {
        EFIHeader->MyLBA = 1ULL;
        EFIHeader->AlternateLBA = Disk->SectorCount - 1ULL;
    }
    else
    {
        EFIHeader->MyLBA = Disk->SectorCount - 1ULL;
        EFIHeader->AlternateLBA = 1ULL;
    }
    /* Fill in with received data */
    EFIHeader->FirstUsableLBA = FirstUsableLBA;
    EFIHeader->LastUsableLBA = LastUsableLBA;
    EFIHeader->DiskGUID = DiskGUID;
    /* Check whether we're writing primary or backup
     * That way, we can ajust LBA setting:
     * On primary, partition entries are just after header, so sector 2
     * On backup, partition entries are just before header, so, last sector minus partition table size
     */
    if (!WriteBackupTable)
    {
        EFIHeader->PartitionEntryLBA = EFIHeader->MyLBA + 1ULL;
    }
    else
    {
        EFIHeader->PartitionEntryLBA = EFIHeader->MyLBA - PartitionsSizeSector;
    }
    /* Complete filling in */
    EFIHeader->NumberOfEntries = NumberOfEntries;
    EFIHeader->SizeOfPartitionEntry = PARTITION_ENTRY_SIZE;
    EFIHeader->PartitionEntryCRC32 = PartitionEntryCRC32;
    /* Finally, compute header checksum */
    EFIHeader->HeaderCRC32 = RtlComputeCrc32(0, (PUCHAR)EFIHeader, sizeof(EFI_PARTITION_HEADER));

    /* Debug the way we'll break disk, to let user pray */
    DPRINT("FSTUB: About to write the following header for %s table\n", (WriteBackupTable ? "backup" : "primary"));
    DPRINT(" Signature: %I64x\n Revision: %x\n HeaderSize: %x\n HeaderCRC32: %x\n",
           EFIHeader->Signature, EFIHeader->Revision, EFIHeader->HeaderSize, EFIHeader->HeaderCRC32);
    DPRINT(" MyLBA: %I64x\n AlternateLBA: %I64x\n FirstUsableLBA: %I64x\n LastUsableLBA: %I64x\n",
           EFIHeader->MyLBA, EFIHeader->AlternateLBA, EFIHeader->FirstUsableLBA, EFIHeader->LastUsableLBA);
    DPRINT(" PartitionEntryLBA: %I64x\n NumberOfEntries: %x\n SizeOfPartitionEntry: %x\n PartitionEntryCRC32: %x\n",
           EFIHeader->PartitionEntryLBA, EFIHeader->NumberOfEntries,
           EFIHeader->SizeOfPartitionEntry, EFIHeader->PartitionEntryCRC32);

    /* Write header to disk */
    return FstubWriteSector(Disk->DeviceObject,
                            Disk->SectorSize,
                            EFIHeader->MyLBA,
                            Disk->Buffer);
}

NTSTATUS
NTAPI
FstubWritePartitionTableEFI(IN PDISK_INFORMATION Disk,
                            IN GUID DiskGUID,
                            IN ULONG MaxPartitionCount,
                            IN ULONGLONG FirstUsableLBA,
                            IN ULONGLONG LastUsableLBA,
                            IN BOOLEAN WriteBackupTable,
                            IN ULONG PartitionCount,
                            IN PPARTITION_INFORMATION_EX PartitionEntries OPTIONAL)
{
    NTSTATUS Status;
    EFI_PARTITION_ENTRY Entry;
    ULONG i, WrittenPartitions, SectoredPartitionEntriesSize, PartitionEntryCRC32;
    PAGED_CODE();

    ASSERT(Disk);
    ASSERT(MaxPartitionCount >= 128);
    ASSERT(PartitionCount <= MaxPartitionCount);

    PartitionEntryCRC32 = 0;
    /* Count how much sectors we'll have to read to read the whole partition table */
    SectoredPartitionEntriesSize = (MaxPartitionCount * PARTITION_ENTRY_SIZE) / Disk->SectorSize;

    for (i = 0, WrittenPartitions = 0; i < PartitionCount; i++)
    {
        /* If partition GUID is 00000000-0000-0000-0000-000000000000, then it's unused, skip it */
        if (PartitionEntries[i].Gpt.PartitionType.Data1 == 0 &&
            PartitionEntries[i].Gpt.PartitionType.Data2 == 0 &&
            PartitionEntries[i].Gpt.PartitionType.Data3 == 0 &&
            ((PULONGLONG)PartitionEntries[i].Gpt.PartitionType.Data4)[0] == 0)
        {
            continue;
        }

        /* Copy the entry in the partition entry format */
        FstubCopyEntryEFI(&Entry, &PartitionEntries[i], Disk->SectorSize);
        /* Then write the entry to the disk */
        Status = FstubWriteEntryEFI(Disk,
                                    SectoredPartitionEntriesSize,
                                    WrittenPartitions,
                                    &Entry,
                                    WriteBackupTable,
                                    FALSE,
                                    &PartitionEntryCRC32);
        if (!NT_SUCCESS(Status))
        {
            return Status;
        }
        WrittenPartitions++;
    }

    /* Zero the buffer to write zeros to the disk */
    RtlZeroMemory(&Entry, sizeof(EFI_PARTITION_ENTRY));
    /* Write the disks with zeros for every unused remaining partition entry */
    for (i = WrittenPartitions; i < MaxPartitionCount; i++)
    {
        Status = FstubWriteEntryEFI(Disk,
                                    SectoredPartitionEntriesSize,
                                    i,
                                    &Entry,
                                    WriteBackupTable,
                                    FALSE,
                                    &PartitionEntryCRC32);
        if (!NT_SUCCESS(Status))
        {
            return Status;
        }
    }

    /* Once we're done, write the GPT header */
    return FstubWriteHeaderEFI(Disk,
                               SectoredPartitionEntriesSize,
                               DiskGUID,
                               MaxPartitionCount,
                               FirstUsableLBA,
                               LastUsableLBA,
                               PartitionEntryCRC32,
                               WriteBackupTable);
}

NTSTATUS
NTAPI
FstubWritePartitionTableMBR(IN PDISK_INFORMATION Disk,
                            IN PDRIVE_LAYOUT_INFORMATION_EX LayoutEx)
{
    NTSTATUS Status;
    PDRIVE_LAYOUT_INFORMATION DriveLayout;
    PAGED_CODE();

    ASSERT(IS_VALID_DISK_INFO(Disk));
    ASSERT(LayoutEx);

    /* Convert data to the correct format */
    DriveLayout = FstubConvertExtendedToLayout(LayoutEx);
    if (!DriveLayout)
    {
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* Really write information */
    Status = IoWritePartitionTable(Disk->DeviceObject,
                                   Disk->SectorSize,
                                   Disk->DiskGeometry.Geometry.SectorsPerTrack,
                                   Disk->DiskGeometry.Geometry.TracksPerCylinder,
                                   DriveLayout);

    /* Free allocated structure and return */
    ExFreePoolWithTag(DriveLayout, TAG_FSTUB);
    return Status;
}

NTSTATUS
NTAPI
FstubWriteSector(IN PDEVICE_OBJECT DeviceObject,
                 IN ULONG SectorSize,
                 IN ULONGLONG StartingSector OPTIONAL,
                 IN PUSHORT Buffer)
{
    PIRP Irp;
    KEVENT Event;
    NTSTATUS Status;
    LARGE_INTEGER StartingOffset;
    IO_STATUS_BLOCK IoStatusBlock;
    PIO_STACK_LOCATION IoStackLocation;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(Buffer);
    ASSERT(SectorSize);

    /* Compute starting offset */
    StartingOffset.QuadPart = StartingSector * SectorSize;

    /* Initialize waiting event */
    KeInitializeEvent(&Event, NotificationEvent, FALSE);

    /* Prepare IRP */
    Irp = IoBuildSynchronousFsdRequest(IRP_MJ_WRITE,
                                       DeviceObject,
                                       Buffer,
                                       SectorSize,
                                       &StartingOffset,
                                       &Event,
                                       &IoStatusBlock);
    if (!Irp)
    {
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* Override volume verify */
    IoStackLocation = IoGetNextIrpStackLocation(Irp);
    IoStackLocation->Flags |= SL_OVERRIDE_VERIFY_VOLUME;

    /* Then call driver, and wait for completion if needed */
    Status = IoCallDriver(DeviceObject, Irp);
    if (Status == STATUS_PENDING)
    {
        KeWaitForSingleObject(&Event, Executive, KernelMode, FALSE, NULL);
        Status = IoStatusBlock.Status;
    }

    return Status;
}

/* FUNCTIONS *****************************************************************/

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoCreateDisk(IN PDEVICE_OBJECT DeviceObject,
             IN struct _CREATE_DISK* Disk)
{
    PARTITION_STYLE PartitionStyle;
    PAGED_CODE();

    ASSERT(DeviceObject);

    /* Get partition style. If caller didn't provided data, assume it's raw */
    PartitionStyle = ((Disk) ? Disk->PartitionStyle : PARTITION_STYLE_RAW);
    /* Then, call appropriate internal function */
    switch (PartitionStyle)
    {
        case PARTITION_STYLE_MBR:
            return FstubCreateDiskMBR(DeviceObject, &(Disk->Mbr));
        case PARTITION_STYLE_GPT:
            return FstubCreateDiskEFI(DeviceObject, &(Disk->Gpt));
        case PARTITION_STYLE_RAW:
            return FstubCreateDiskRaw(DeviceObject);
        default:
            return STATUS_NOT_SUPPORTED;
    }
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoGetBootDiskInformation(IN OUT PBOOTDISK_INFORMATION BootDiskInformation,
                         IN ULONG Size)
{
    PIRP Irp;
    KEVENT Event;
    PLIST_ENTRY NextEntry;
    PFILE_OBJECT FileObject;
    DISK_GEOMETRY DiskGeometry;
    PDEVICE_OBJECT DeviceObject;
    UNICODE_STRING DeviceStringW;
    IO_STATUS_BLOCK IoStatusBlock;
    CHAR Buffer[128], ArcBuffer[128];
    NTSTATUS Status = STATUS_SUCCESS;
    BOOLEAN SingleDisk, IsBootDiskInfoEx;
    PARC_DISK_SIGNATURE ArcDiskSignature;
    PARC_DISK_INFORMATION ArcDiskInformation;
    PARTITION_INFORMATION_EX PartitionInformation;
    PDRIVE_LAYOUT_INFORMATION_EX DriveLayout = NULL;
    ULONG DiskCount, DiskNumber, Signature, PartitionNumber;
    ANSI_STRING ArcBootString, ArcSystemString, DeviceStringA, ArcNameStringA;
    extern PLOADER_PARAMETER_BLOCK IopLoaderBlock;
    PAGED_CODE();

    /* Get loader block. If it's null, we come to late */
    if (!IopLoaderBlock)
    {
        return STATUS_TOO_LATE;
    }

    /* Check buffer size */
    if (Size < sizeof(BOOTDISK_INFORMATION))
    {
        return STATUS_INVALID_PARAMETER;
    }

    /* Init some useful stuff:
     * Get arc disks information
     * Check whether we have a single disk
     * Check received structure size (extended or not?)
     * Init boot strings (system/boot)
     * Finaly, get disk count
     */
    ArcDiskInformation = IopLoaderBlock->ArcDiskInformation;
    SingleDisk = IsListEmpty(&(ArcDiskInformation->DiskSignatureListHead));
    IsBootDiskInfoEx = (Size >= sizeof(BOOTDISK_INFORMATION_EX));
    RtlInitAnsiString(&ArcBootString, IopLoaderBlock->ArcBootDeviceName);
    RtlInitAnsiString(&ArcSystemString, IopLoaderBlock->ArcHalDeviceName);
    DiskCount = IoGetConfigurationInformation()->DiskCount;

    /* If no disk, return success */
    if (DiskCount == 0)
    {
        return STATUS_SUCCESS;
    }

    /* Now, browse all disks */
    for (DiskNumber = 0; DiskNumber < DiskCount; DiskNumber++)
    {
        /* Create the device name */
        sprintf(Buffer, "\\Device\\Harddisk%lu\\Partition0", DiskNumber);
        RtlInitAnsiString(&DeviceStringA, Buffer);
        Status = RtlAnsiStringToUnicodeString(&DeviceStringW, &DeviceStringA, TRUE);
        if (!NT_SUCCESS(Status))
        {
            continue;
        }

        /* Get its device object */
        Status = IoGetDeviceObjectPointer(&DeviceStringW,
                                          FILE_READ_ATTRIBUTES,
                                          &FileObject,
                                          &DeviceObject);
        RtlFreeUnicodeString(&DeviceStringW);
        if (!NT_SUCCESS(Status))
        {
            continue;
        }

        /* Prepare for getting disk geometry */
        Irp = IoBuildDeviceIoControlRequest(IOCTL_DISK_GET_DRIVE_GEOMETRY,
                                            DeviceObject,
                                            NULL,
                                            0,
                                            &DiskGeometry,
                                            sizeof(DISK_GEOMETRY),
                                            FALSE,
                                            &Event,
                                            &IoStatusBlock);
        if (!Irp)
        {
            ObDereferenceObject(FileObject);
            continue;
        }

        /* Then, call the drive, and wait for it if needed */
        KeInitializeEvent(&Event, NotificationEvent, FALSE);
        Status = IoCallDriver(DeviceObject, Irp);
        if (Status == STATUS_PENDING)
        {
            KeWaitForSingleObject(&Event, Executive, KernelMode, FALSE, NULL);
            Status = IoStatusBlock.Status;
        }
        if (!NT_SUCCESS(Status))
        {
            ObDereferenceObject(FileObject);
            continue;
        }

        /* Read partition table */
        Status = IoReadPartitionTableEx(DeviceObject,
                                        &DriveLayout);

        /* FileObject, you can go! */
        ObDereferenceObject(FileObject);

        if (!NT_SUCCESS(Status))
        {
            continue;
        }

        /* Ensure we have at least 512 bytes per sector */
        if (DiskGeometry.BytesPerSector < 512)
        {
            DiskGeometry.BytesPerSector = 512;
        }

        /* Now, for each arc disk, try to find the matching */
        for (NextEntry = ArcDiskInformation->DiskSignatureListHead.Flink;
             NextEntry != &ArcDiskInformation->DiskSignatureListHead;
             NextEntry = NextEntry->Flink)
        {
            ArcDiskSignature = CONTAINING_RECORD(NextEntry,
                                                 ARC_DISK_SIGNATURE,
                                                 ListEntry);
            /* If they matches, ie
             * - There's only one disk for both BIOS and detected
             * - Signatures are matching
             * - This is MBR
             * (We don't check checksums here)
             */
            if (((SingleDisk && DiskCount == 1) ||
                (IopVerifyDiskSignature(DriveLayout, ArcDiskSignature, &Signature))) &&
                (DriveLayout->PartitionStyle == PARTITION_STYLE_MBR))
            {
                /* Create arc name */
                sprintf(ArcBuffer, "\\ArcName\\%s", ArcDiskSignature->ArcName);
                RtlInitAnsiString(&ArcNameStringA, ArcBuffer);

                /* Browse all partitions */
                for (PartitionNumber = 1; PartitionNumber <= DriveLayout->PartitionCount; PartitionNumber++)
                {
                    /* Create its device name */
                    sprintf(Buffer, "\\Device\\Harddisk%lu\\Partition%lu", DiskNumber, PartitionNumber);
                    RtlInitAnsiString(&DeviceStringA, Buffer);
                    Status = RtlAnsiStringToUnicodeString(&DeviceStringW, &DeviceStringA, TRUE);
                    if (!NT_SUCCESS(Status))
                    {
                        continue;
                    }

                    /* If IopVerifyDiskSignature returned no signature, take the one from DriveLayout */
                    if (!Signature)
                    {
                        Signature = DriveLayout->Mbr.Signature;
                    }

                    /* Create partial arc name */
                    sprintf(ArcBuffer, "%spartition(%lu)", ArcDiskSignature->ArcName, PartitionNumber);
                    RtlInitAnsiString(&ArcNameStringA, ArcBuffer);

                    /* If it's matching boot string */
                    if (RtlEqualString(&ArcNameStringA, &ArcBootString, TRUE))
                    {
                        /*  Then, fill in information about boot device */
                        BootDiskInformation->BootDeviceSignature = Signature;

                        /* Get its device object */
                        Status = IoGetDeviceObjectPointer(&DeviceStringW,
                                                          FILE_READ_ATTRIBUTES,
                                                          &FileObject,
                                                          &DeviceObject);
                        if (!NT_SUCCESS(Status))
                        {
                            RtlFreeUnicodeString(&DeviceStringW);
                            continue;
                        }

                        /* And call the drive to get information about partition */
                        Irp = IoBuildDeviceIoControlRequest(IOCTL_DISK_GET_PARTITION_INFO_EX,
                                                            DeviceObject,
                                                            NULL,
                                                            0,
                                                            &PartitionInformation,
                                                            sizeof(PARTITION_INFORMATION_EX),
                                                            FALSE,
                                                            &Event,
                                                            &IoStatusBlock);
                        if (!Irp)
                        {
                            ObDereferenceObject(FileObject);
                            RtlFreeUnicodeString(&DeviceStringW);
                            continue;
                        }

                        /* Call & wait if needed */
                        KeInitializeEvent(&Event, NotificationEvent, FALSE);
                        Status = IoCallDriver(DeviceObject, Irp);
                        if (Status == STATUS_PENDING)
                        {
                            KeWaitForSingleObject(&Event, Executive, KernelMode, FALSE, NULL);
                            Status = IoStatusBlock.Status;
                        }
                        if (!NT_SUCCESS(Status))
                        {
                            ObDereferenceObject(FileObject);
                            RtlFreeUnicodeString(&DeviceStringW);
                            continue;
                        }

                        /* We get partition offset as demanded and return it */
                        BootDiskInformation->BootPartitionOffset = PartitionInformation.StartingOffset.QuadPart;

                        /* If called passed a BOOTDISK_INFORMATION_EX structure, give more intel */
                        if (IsBootDiskInfoEx)
                        {
                            /* Is PT MBR or GPT? */
                            if (DriveLayout->PartitionStyle == PARTITION_STYLE_GPT)
                            {
                                ((PBOOTDISK_INFORMATION_EX)BootDiskInformation)->BootDeviceGuid = DriveLayout->Gpt.DiskId;
                                ((PBOOTDISK_INFORMATION_EX)BootDiskInformation)->BootDeviceIsGpt = TRUE;
                            }
                            else
                            {
                                ((PBOOTDISK_INFORMATION_EX)BootDiskInformation)->BootDeviceIsGpt = FALSE;
                            }
                        }

                        /* Dereference FileObject */
                        ObDereferenceObject(FileObject);
                    }

                    /* If it's matching system string */
                    if (RtlEqualString(&ArcNameStringA, &ArcSystemString, TRUE))
                    {
                        /* Then, fill in information about the system device */
                        BootDiskInformation->SystemDeviceSignature = Signature;

                        /* Get its device object */
                        Status = IoGetDeviceObjectPointer(&DeviceStringW,
                                                          FILE_READ_ATTRIBUTES,
                                                          &FileObject,
                                                          &DeviceObject);
                        if (!NT_SUCCESS(Status))
                        {
                            RtlFreeUnicodeString(&DeviceStringW);
                            continue;
                        }

                        /* And call the drive to get information about partition */
                        Irp = IoBuildDeviceIoControlRequest(IOCTL_DISK_GET_PARTITION_INFO_EX,
                                                            DeviceObject,
                                                            NULL,
                                                            0,
                                                            &PartitionInformation,
                                                            sizeof(PARTITION_INFORMATION_EX),
                                                            FALSE,
                                                            &Event,
                                                            &IoStatusBlock);
                        if (!Irp)
                        {
                            ObDereferenceObject(FileObject);
                            RtlFreeUnicodeString(&DeviceStringW);
                            continue;
                        }

                        /* Call & wait if needed */
                        KeInitializeEvent(&Event, NotificationEvent, FALSE);
                        Status = IoCallDriver(DeviceObject, Irp);
                        if (Status == STATUS_PENDING)
                        {
                            KeWaitForSingleObject(&Event, Executive, KernelMode, FALSE, NULL);
                            Status = IoStatusBlock.Status;
                        }
                        if (!NT_SUCCESS(Status))
                        {
                            ObDereferenceObject(FileObject);
                            RtlFreeUnicodeString(&DeviceStringW);
                            continue;
                        }

                        /* We get partition offset as demanded and return it */
                        BootDiskInformation->SystemPartitionOffset = PartitionInformation.StartingOffset.QuadPart;

                        /* If called passed a BOOTDISK_INFORMATION_EX structure, give more intel */
                        if (IsBootDiskInfoEx)
                        {
                            /* Is PT MBR or GPT? */
                            if (DriveLayout->PartitionStyle == PARTITION_STYLE_GPT)
                            {
                                ((PBOOTDISK_INFORMATION_EX)BootDiskInformation)->SystemDeviceGuid = DriveLayout->Gpt.DiskId;
                                ((PBOOTDISK_INFORMATION_EX)BootDiskInformation)->SystemDeviceIsGpt = TRUE;
                            }
                            else
                            {
                                ((PBOOTDISK_INFORMATION_EX)BootDiskInformation)->SystemDeviceIsGpt = FALSE;
                           }
                        }

                        /* Dereference FileObject */
                        ObDereferenceObject(FileObject);
                    }

                    /* Release device string */
                    RtlFreeUnicodeString(&DeviceStringW);
                }
            }
        }

        /* Finally, release drive layout structure */
        ExFreePool(DriveLayout);
    }

    /* And return */
    return Status;
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoReadDiskSignature(IN PDEVICE_OBJECT DeviceObject,
                    IN ULONG BytesPerSector,
                    OUT PDISK_SIGNATURE Signature)
{
    PULONG Buffer;
    NTSTATUS Status;
    ULONG HeaderCRC32, i, CheckSum;
    PEFI_PARTITION_HEADER EFIHeader;
    PPARTITION_DESCRIPTOR PartitionDescriptor;
    PAGED_CODE();

    /* Ensure we'll read at least 512 bytes */
    if (BytesPerSector < 512)
    {
        BytesPerSector = 512;
    }

    /* Allocate a buffer for reading operations */
    Buffer = ExAllocatePoolWithTag(NonPagedPoolCacheAligned, BytesPerSector, TAG_FSTUB);
    if (!Buffer)
    {
        return STATUS_NO_MEMORY;
    }

    /* Read first sector (sector 0) for MBR */
    Status = FstubReadSector(DeviceObject,
                             BytesPerSector,
                             0ULL,
                             (PUSHORT)Buffer);
    if (!NT_SUCCESS(Status))
    {
        goto Cleanup;
    }

    /* Get the partition descriptor array */
    PartitionDescriptor = (PPARTITION_DESCRIPTOR)
                          &(Buffer[PARTITION_TABLE_OFFSET]);
    /* Check partitions types: if first is 0xEE and all the others 0, we have GPT */
    if (PartitionDescriptor[0].PartitionType == EFI_PMBR_OSTYPE_EFI &&
        PartitionDescriptor[1].PartitionType == 0 &&
        PartitionDescriptor[2].PartitionType == 0 &&
        PartitionDescriptor[3].PartitionType == 0)
    {
        /* If we have GPT, read second sector (sector 1) for GPT header */
        Status = FstubReadSector(DeviceObject,
                                 BytesPerSector,
                                 1ULL,
                                 (PUSHORT)Buffer);
        if (!NT_SUCCESS(Status))
        {
            goto Cleanup;
        }
        EFIHeader = (PEFI_PARTITION_HEADER)Buffer;

        /* First check signature
         * Then, check version (we only support v1
         * Finally check header size
         */
        if (EFIHeader->Signature != EFI_HEADER_SIGNATURE ||
            EFIHeader->Revision != EFI_HEADER_REVISION_1 ||
            EFIHeader->HeaderSize != sizeof(EFI_PARTITION_HEADER))
        {
            Status = STATUS_DISK_CORRUPT_ERROR;
            goto Cleanup;
        }

        /* Save current checksum */
        HeaderCRC32 = EFIHeader->HeaderCRC32;
        /* Then zero the one in EFI header. This is needed to compute header checksum */
        EFIHeader->HeaderCRC32 = 0;
        /* Compute header checksum and compare with the one present in partition table */
        if (RtlComputeCrc32(0, (PUCHAR)Buffer, sizeof(EFI_PARTITION_HEADER)) != HeaderCRC32)
        {
            Status = STATUS_DISK_CORRUPT_ERROR;
            goto Cleanup;
        }

        /* Set partition table style to GPT and return disk GUID */
        Signature->PartitionStyle = PARTITION_STYLE_GPT;
        Signature->Gpt.DiskId = EFIHeader->DiskGUID;
    }
    else
    {
        /* Compute MBR checksum */
        for (i = 0, CheckSum = 0; i < 512 / sizeof(ULONG) ; i++)
        {
            CheckSum += Buffer[i];
        }

        /* Set partition table style to MBR and return signature (offset 440) and checksum */
        Signature->PartitionStyle = PARTITION_STYLE_MBR;
        Signature->Mbr.Signature = Buffer[PARTITION_TABLE_OFFSET / 2 - 1];
        Signature->Mbr.CheckSum = CheckSum;
    }

Cleanup:
    /* Free buffer and return */
    ExFreePoolWithTag(Buffer, TAG_FSTUB);
    return Status;
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoReadPartitionTableEx(IN PDEVICE_OBJECT DeviceObject,
                       IN struct _DRIVE_LAYOUT_INFORMATION_EX** DriveLayout)
{
    NTSTATUS Status;
    PDISK_INFORMATION Disk;
    PARTITION_STYLE PartitionStyle;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(DriveLayout);

    /* First of all, allocate internal structure */
    Status = FstubAllocateDiskInformation(DeviceObject, &Disk, 0);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }
    ASSERT(Disk);

    /* Then, detect partition style (MBR? GTP/EFI? RAW?) */
    Status = FstubDetectPartitionStyle(Disk, &PartitionStyle);
    if (!NT_SUCCESS(Status))
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }

    /* Here partition table is really read, depending on its style */
    switch (PartitionStyle)
    {
        case PARTITION_STYLE_MBR:
        case PARTITION_STYLE_RAW:
            Status = FstubReadPartitionTableMBR(Disk, FALSE, DriveLayout);
            break;

        case PARTITION_STYLE_GPT:
             /* Read primary table */
             Status = FstubReadPartitionTableEFI(Disk, FALSE, DriveLayout);
             /* If it failed, try reading backup table */
             if (!NT_SUCCESS(Status))
             {
                 Status = FstubReadPartitionTableEFI(Disk, TRUE, DriveLayout);
             }
             break;

        default:
             DPRINT("Unknown partition type\n");
             Status = STATUS_UNSUCCESSFUL;
    }

    /* It's over, internal structure not needed anymore */
    FstubFreeDiskInformation(Disk);

    /* In case of success, print data */
    if (NT_SUCCESS(Status))
    {
        FstubDbgPrintDriveLayoutEx(*DriveLayout);
    }

    return Status;
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoSetPartitionInformationEx(IN PDEVICE_OBJECT DeviceObject,
                            IN ULONG PartitionNumber,
                            IN struct _SET_PARTITION_INFORMATION_EX* PartitionInfo)
{
    NTSTATUS Status;
    PDISK_INFORMATION Disk;
    PARTITION_STYLE PartitionStyle;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(PartitionInfo);

    /* Debug given modifications */
    FstubDbgPrintSetPartitionEx(PartitionInfo, PartitionNumber);

    /* Allocate internal structure */
    Status = FstubAllocateDiskInformation(DeviceObject, &Disk, NULL);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }

    /* Get partition table style on disk */
    Status = FstubDetectPartitionStyle(Disk, &PartitionStyle);
    if (!NT_SUCCESS(Status))
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }

    /* If it's not matching partition style given in modifications, give up */
    if (PartitionInfo->PartitionStyle != PartitionStyle)
    {
        FstubFreeDiskInformation(Disk);
        return STATUS_INVALID_PARAMETER;
    }

    /* Finally, handle modifications using proper function */
    switch (PartitionStyle)
    {
        case PARTITION_STYLE_MBR:
            Status = IoSetPartitionInformation(DeviceObject,
                                               Disk->SectorSize,
                                               PartitionNumber,
                                               PartitionInfo->Mbr.PartitionType);
            break;
        case PARTITION_STYLE_GPT:
            Status = FstubSetPartitionInformationEFI(Disk,
                                                     PartitionNumber,
                                                     &(PartitionInfo->Gpt));
            break;
        default:
            Status = STATUS_NOT_SUPPORTED;
    }

    /* Release internal structure and return */
    FstubFreeDiskInformation(Disk);
    return Status;
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoVerifyPartitionTable(IN PDEVICE_OBJECT DeviceObject,
                       IN BOOLEAN FixErrors)
{
    NTSTATUS Status;
    PDISK_INFORMATION Disk;
    PARTITION_STYLE PartitionStyle;
    PAGED_CODE();

    ASSERT(DeviceObject);

    /* Allocate internal structure */
    Status = FstubAllocateDiskInformation(DeviceObject, &Disk, NULL);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }
    ASSERT(Disk);

    /* Get partition table style on disk */
    Status = FstubDetectPartitionStyle(Disk, &PartitionStyle);
    if (!NT_SUCCESS(Status))
    {
        FstubFreeDiskInformation(Disk);
        return Status;
    }

    /* Action will depend on partition style */
    switch (PartitionStyle)
    {
        /* For MBR, assume it's always OK */
        case PARTITION_STYLE_MBR:
            Status = STATUS_SUCCESS;
            break;
        /* For GPT, call internal function */
        case PARTITION_STYLE_GPT:
            Status = FstubVerifyPartitionTableEFI(Disk, FixErrors);
            break;
        /* Otherwise, signal we can't work */
        default:
            Status = STATUS_NOT_SUPPORTED;
    }

    /* Release internal structure and return */
    FstubFreeDiskInformation(Disk);
    return Status;
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoWritePartitionTableEx(IN PDEVICE_OBJECT DeviceObject,
                        IN struct _DRIVE_LAYOUT_INFORMATION_EX* DriveLayout)
{
    NTSTATUS Status;
    PDISK_INFORMATION Disk;
    ULONGLONG SectorsForPartitions;
    EFI_PARTITION_HEADER EfiHeader;
    PAGED_CODE();

    ASSERT(DeviceObject);
    ASSERT(DriveLayout);

    /* Debug partition table that must be written */
    FstubDbgPrintDriveLayoutEx(DriveLayout);

    /* Allocate internal structure */
    Status = FstubAllocateDiskInformation(DeviceObject, &Disk, 0);
    if (!NT_SUCCESS(Status))
    {
        return Status;
    }
    ASSERT(Disk);

    switch (DriveLayout->PartitionStyle)
    {
        case PARTITION_STYLE_MBR:
            Status = FstubWritePartitionTableMBR(Disk, DriveLayout);
            break;

        case PARTITION_STYLE_GPT:
            /* Read primary table header */
            Status = FstubReadHeaderEFI(Disk,
                                        FALSE,
                                        &EfiHeader);
            /* If it failed, try reading back table header */
            if (!NT_SUCCESS(Status))
            {
                Status = FstubReadHeaderEFI(Disk,
                                            TRUE,
                                            &EfiHeader);
            }

            /* We have a header! */
            if (NT_SUCCESS(Status))
            {
                /* Check if there are enough places for the partitions to be written */
                if (DriveLayout->PartitionCount <= EfiHeader.NumberOfEntries)
                {
                    /* Count number of sectors needed to store partitions */
                    SectorsForPartitions = (EfiHeader.NumberOfEntries * PARTITION_ENTRY_SIZE) / Disk->SectorSize;
                    /* Set first usable LBA: Legacy MBR + GPT header + Partitions entries */
                    EfiHeader.FirstUsableLBA = SectorsForPartitions + 2;
                    /* Set last usable LBA: Last sector - GPT header - Partitions entries */
                    EfiHeader.LastUsableLBA = Disk->SectorCount - SectorsForPartitions - 1;
                    /* Write primary table */
                    Status = FstubWritePartitionTableEFI(Disk,
                                                         EfiHeader.DiskGUID,
                                                         EfiHeader.NumberOfEntries,
                                                         EfiHeader.FirstUsableLBA,
                                                         EfiHeader.LastUsableLBA,
                                                         FALSE,
                                                         DriveLayout->PartitionCount,
                                                         DriveLayout->PartitionEntry);
                    /* If it succeed, also update backup table */
                    if (NT_SUCCESS(Status))
                    {
                        Status = FstubWritePartitionTableEFI(Disk,
                                                             EfiHeader.DiskGUID,
                                                             EfiHeader.NumberOfEntries,
                                                             EfiHeader.FirstUsableLBA,
                                                             EfiHeader.LastUsableLBA,
                                                             TRUE,
                                                             DriveLayout->PartitionCount,
                                                             DriveLayout->PartitionEntry);
                    }
                }
            }
            break;

        default:
            DPRINT("Unsupported partition style: %ld\n", DriveLayout->PartitionStyle);
            Status = STATUS_NOT_SUPPORTED;
    }

    /* It's over, internal structure not needed anymore */
    FstubFreeDiskInformation(Disk);

    return Status;
}

/* EOF */