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