361 lines
10 KiB
C
361 lines
10 KiB
C
/*++
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Copyright (c) 1992 Microsoft Corporation
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Module Name:
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ntfs_rec.c
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Abstract:
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This module contains the mini-file system recognizer for NTFS.
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Author:
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Darryl E. Havens (darrylh) 8-dec-1992
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Environment:
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Kernel mode, local to I/O system
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Revision History:
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--*/
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#include "fs_rec.h"
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#include "ntfs_rec.h"
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//
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// The local debug trace level
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//
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#define Dbg (FSREC_DEBUG_LEVEL_NTFS)
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(PAGE,NtfsRecFsControl)
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#pragma alloc_text(PAGE,IsNtfsVolume)
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#endif // ALLOC_PRAGMA
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NTSTATUS
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NtfsRecFsControl(
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IN PDEVICE_OBJECT DeviceObject,
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IN PIRP Irp
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)
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/*++
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Routine Description:
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This function performs the mount and driver reload functions for this mini-
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file system recognizer driver.
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Arguments:
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DeviceObject - Pointer to this driver's device object.
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Irp - Pointer to the I/O Request Packet (IRP) representing the function to
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be performed.
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Return Value:
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The function value is the final status of the operation.
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--*/
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{
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NTSTATUS status;
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PIO_STACK_LOCATION irpSp;
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PDEVICE_EXTENSION deviceExtension;
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PDEVICE_OBJECT targetDevice;
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PPACKED_BOOT_SECTOR buffer;
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LARGE_INTEGER byteOffset;
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LARGE_INTEGER secondByteOffset;
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LARGE_INTEGER lastByteOffset;
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UNICODE_STRING driverName;
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ULONG bytesPerSector;
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LARGE_INTEGER numberOfSectors;
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PAGED_CODE();
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//
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// Begin by determining what function that is to be performed.
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//
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deviceExtension = (PDEVICE_EXTENSION) DeviceObject->DeviceExtension;
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irpSp = IoGetCurrentIrpStackLocation( Irp );
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switch ( irpSp->MinorFunction ) {
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case IRP_MN_MOUNT_VOLUME:
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//
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// Attempt to mount a volume: Determine whether or not the volume in
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// question is an NTFS volume and, if so, let the I/O system know that it
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// is by returning a special status code so that this driver can get
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// called back to load the NTFS file system.
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//
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status = STATUS_UNRECOGNIZED_VOLUME;
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//
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// Attempt to determine whether or not the target volume being mounted
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// is an NTFS volume.
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//
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targetDevice = irpSp->Parameters.MountVolume.DeviceObject;
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if (FsRecGetDeviceSectorSize( targetDevice,
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&bytesPerSector ) &&
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FsRecGetDeviceSectors( targetDevice,
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bytesPerSector,
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&numberOfSectors )) {
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byteOffset.QuadPart = 0;
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buffer = NULL;
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secondByteOffset.QuadPart = numberOfSectors.QuadPart >> 1;
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secondByteOffset.QuadPart *= (LONG) bytesPerSector;
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lastByteOffset.QuadPart = (numberOfSectors.QuadPart - 1) * (LONG) bytesPerSector;
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if (FsRecReadBlock( targetDevice,
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&byteOffset,
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sizeof( PACKED_BOOT_SECTOR ),
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bytesPerSector,
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(PVOID *)&buffer,
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NULL ))
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{
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if (IsNtfsVolume( buffer, bytesPerSector, &numberOfSectors )) {
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status = STATUS_FS_DRIVER_REQUIRED;
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}
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} else {
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if (FsRecReadBlock( targetDevice,
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&secondByteOffset,
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sizeof( PACKED_BOOT_SECTOR ),
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bytesPerSector,
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(PVOID *)&buffer,
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NULL ) &&
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IsNtfsVolume( buffer, bytesPerSector, &numberOfSectors )) {
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status = STATUS_FS_DRIVER_REQUIRED;
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} else {
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if (FsRecReadBlock( targetDevice,
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&lastByteOffset,
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sizeof( PACKED_BOOT_SECTOR ),
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bytesPerSector,
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(PVOID *)&buffer,
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NULL ) &&
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IsNtfsVolume( buffer, bytesPerSector, &numberOfSectors )) {
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status = STATUS_FS_DRIVER_REQUIRED;
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}
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}
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}
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if (buffer != NULL) {
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ExFreePool( buffer );
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}
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}
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break;
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case IRP_MN_LOAD_FILE_SYSTEM:
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status = FsRecLoadFileSystem( DeviceObject,
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L"\\Registry\\Machine\\System\\CurrentControlSet\\Services\\Ntfs" );
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break;
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default:
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status = STATUS_INVALID_DEVICE_REQUEST;
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}
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//
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// Finally, complete the request and return the same status code to the
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// caller.
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//
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Irp->IoStatus.Status = status;
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IoCompleteRequest( Irp, IO_NO_INCREMENT );
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return status;
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}
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BOOLEAN
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IsNtfsVolume(
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IN PPACKED_BOOT_SECTOR BootSector,
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IN ULONG BytesPerSector,
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IN PLARGE_INTEGER NumberOfSectors
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)
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/*++
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Routine Description:
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This routine looks at the buffer passed in which contains the NTFS boot
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sector and determines whether or not it represents an NTFS volume.
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Arguments:
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BootSector - Pointer to buffer containing a potential NTFS boot sector.
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BytesPerSector - Supplies the number of bytes per sector for the drive.
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NumberOfSectors - Supplies the number of sectors on the partition.
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Return Value:
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The function returns TRUE if the buffer contains a recognizable NTFS boot
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sector, otherwise it returns FALSE.
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--*/
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{
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PAGED_CODE();
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//
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// Now perform all the checks, starting with the Name and Checksum.
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// The remaining checks should be obvious, including some fields which
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// must be 0 and other fields which must be a small power of 2.
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//
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if (BootSector->Oem[0] == 'N' &&
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BootSector->Oem[1] == 'T' &&
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BootSector->Oem[2] == 'F' &&
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BootSector->Oem[3] == 'S' &&
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BootSector->Oem[4] == ' ' &&
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BootSector->Oem[5] == ' ' &&
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BootSector->Oem[6] == ' ' &&
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BootSector->Oem[7] == ' '
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&&
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//
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// Check number of bytes per sector. The low order byte of this
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// number must be zero (smallest sector size = 0x100) and the
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// high order byte shifted must equal the bytes per sector gotten
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// from the device and stored in the Vcb. And just to be sure,
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// sector size must be less than page size.
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//
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BootSector->PackedBpb.BytesPerSector[0] == 0
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&&
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((ULONG) (BootSector->PackedBpb.BytesPerSector[1] << 8) == BytesPerSector)
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&&
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BootSector->PackedBpb.BytesPerSector[1] << 8 <= PAGE_SIZE
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&&
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//
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// Sectors per cluster must be a power of 2.
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//
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(BootSector->PackedBpb.SectorsPerCluster[0] == 0x1 ||
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BootSector->PackedBpb.SectorsPerCluster[0] == 0x2 ||
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BootSector->PackedBpb.SectorsPerCluster[0] == 0x4 ||
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BootSector->PackedBpb.SectorsPerCluster[0] == 0x8 ||
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BootSector->PackedBpb.SectorsPerCluster[0] == 0x10 ||
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BootSector->PackedBpb.SectorsPerCluster[0] == 0x20 ||
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BootSector->PackedBpb.SectorsPerCluster[0] == 0x40 ||
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BootSector->PackedBpb.SectorsPerCluster[0] == 0x80)
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&&
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//
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// These fields must all be zero. For both Fat and HPFS, some of
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// these fields must be nonzero.
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//
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BootSector->PackedBpb.ReservedSectors[0] == 0 &&
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BootSector->PackedBpb.ReservedSectors[1] == 0 &&
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BootSector->PackedBpb.Fats[0] == 0 &&
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BootSector->PackedBpb.RootEntries[0] == 0 &&
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BootSector->PackedBpb.RootEntries[1] == 0 &&
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BootSector->PackedBpb.Sectors[0] == 0 &&
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BootSector->PackedBpb.Sectors[1] == 0 &&
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BootSector->PackedBpb.SectorsPerFat[0] == 0 &&
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BootSector->PackedBpb.SectorsPerFat[1] == 0 &&
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BootSector->PackedBpb.LargeSectors[0] == 0 &&
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BootSector->PackedBpb.LargeSectors[1] == 0 &&
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BootSector->PackedBpb.LargeSectors[2] == 0 &&
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BootSector->PackedBpb.LargeSectors[3] == 0
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&&
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//
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// Number of Sectors cannot be greater than the number of sectors
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// on the partition.
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//
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!( BootSector->NumberSectors.QuadPart > NumberOfSectors->QuadPart )
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&&
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//
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// Check that both Lcn values are for sectors within the partition.
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//
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!( BootSector->MftStartLcn.QuadPart *
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BootSector->PackedBpb.SectorsPerCluster[0] >
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NumberOfSectors->QuadPart )
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&&
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!( BootSector->Mft2StartLcn.QuadPart *
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BootSector->PackedBpb.SectorsPerCluster[0] >
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NumberOfSectors->QuadPart )
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&&
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//
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// Clusters per file record segment and default clusters for Index
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// Allocation Buffers must be a power of 2. A negative number indicates
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// a shift value to get the actual size of the structure.
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//
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((BootSector->ClustersPerFileRecordSegment >= -31 &&
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BootSector->ClustersPerFileRecordSegment <= -9) ||
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BootSector->ClustersPerFileRecordSegment == 0x1 ||
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BootSector->ClustersPerFileRecordSegment == 0x2 ||
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BootSector->ClustersPerFileRecordSegment == 0x4 ||
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BootSector->ClustersPerFileRecordSegment == 0x8 ||
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BootSector->ClustersPerFileRecordSegment == 0x10 ||
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BootSector->ClustersPerFileRecordSegment == 0x20 ||
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BootSector->ClustersPerFileRecordSegment == 0x40)
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&&
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((BootSector->DefaultClustersPerIndexAllocationBuffer >= -31 &&
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BootSector->DefaultClustersPerIndexAllocationBuffer <= -9) ||
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BootSector->DefaultClustersPerIndexAllocationBuffer == 0x1 ||
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BootSector->DefaultClustersPerIndexAllocationBuffer == 0x2 ||
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BootSector->DefaultClustersPerIndexAllocationBuffer == 0x4 ||
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BootSector->DefaultClustersPerIndexAllocationBuffer == 0x8 ||
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BootSector->DefaultClustersPerIndexAllocationBuffer == 0x10 ||
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BootSector->DefaultClustersPerIndexAllocationBuffer == 0x20 ||
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BootSector->DefaultClustersPerIndexAllocationBuffer == 0x40)) {
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return TRUE;
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} else {
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//
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// This does not appear to be an NTFS volume.
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//
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return FALSE;
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}
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}
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