206 lines
8.9 KiB
C
206 lines
8.9 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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--*/
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#include "fs_rec.h"
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#include "ntfs_rec.h"
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// The local debug trace level
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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 NtfsRecFsControl(IN PDEVICE_OBJECT DeviceObject, IN PIRP Irp)
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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-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 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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// Begin by determining what function that is to be performed.
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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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// Attempt to mount a volume: Determine whether or not the volume in question is an NTFS volume and,
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// 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 called back to load the NTFS file system.
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status = STATUS_UNRECOGNIZED_VOLUME;
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// Attempt to determine whether or not the target volume being mounted is an NTFS volume.
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targetDevice = irpSp->Parameters.MountVolume.DeviceObject;
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if (FsRecGetDeviceSectorSize(targetDevice, &bytesPerSector) &&
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FsRecGetDeviceSectors(targetDevice, bytesPerSector, &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, &byteOffset, sizeof(PACKED_BOOT_SECTOR), bytesPerSector, (PVOID *)&buffer, 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, &secondByteOffset, sizeof(PACKED_BOOT_SECTOR), bytesPerSector, (PVOID *)&buffer, 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, &lastByteOffset, sizeof(PACKED_BOOT_SECTOR), bytesPerSector, (PVOID *)&buffer, 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, 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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// Finally, complete the request and return the same status code to the caller.
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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 IsNtfsVolume(IN PPACKED_BOOT_SECTOR BootSector, IN ULONG BytesPerSector, IN PLARGE_INTEGER NumberOfSectors)
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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 sector and
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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 sector, otherwise it returns FALSE.
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--*/
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{
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PAGED_CODE();
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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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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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// Check number of bytes per sector.
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// The low order byte of this number must be zero (smallest sector size = 0x100) and
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// the high order byte shifted must equal the bytes per sector gotten from the device and stored in the Vcb.
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// And just to be sure, sector size must be less than page size.
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BootSector->PackedBpb.BytesPerSector[0] == 0 &&
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((ULONG)(BootSector->PackedBpb.BytesPerSector[1] << 8) == BytesPerSector) &&
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BootSector->PackedBpb.BytesPerSector[1] << 8 <= PAGE_SIZE &&
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// Sectors per cluster must be a power of 2.
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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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// These fields must all be zero. For both Fat and HPFS, some of these fields must be nonzero.
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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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// Number of Sectors cannot be greater than the number of sectors on the partition.
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!(BootSector->NumberSectors.QuadPart > NumberOfSectors->QuadPart) &&
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// Check that both Lcn values are for sectors within the partition.
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!(BootSector->MftStartLcn.QuadPart * BootSector->PackedBpb.SectorsPerCluster[0] > NumberOfSectors->QuadPart) &&
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!(BootSector->Mft2StartLcn.QuadPart * BootSector->PackedBpb.SectorsPerCluster[0] > NumberOfSectors->QuadPart) &&
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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.
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// A negative number indicates a shift value to get the actual size of the structure.
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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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return FALSE;// This does not appear to be an NTFS volume.
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}
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}
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