354 lines
8.7 KiB
C
354 lines
8.7 KiB
C
/*++
|
||
|
||
Copyright (c) 1992 Microsoft Corporation
|
||
|
||
Module Name:
|
||
|
||
fat_rec.c
|
||
|
||
Abstract:
|
||
|
||
This module contains the mini-file system recognizer for FAT.
|
||
|
||
Author:
|
||
|
||
Darryl E. Havens (darrylh) 8-dec-1992
|
||
|
||
Environment:
|
||
|
||
Kernel mode, local to I/O system
|
||
|
||
Revision History:
|
||
|
||
|
||
--*/
|
||
|
||
#include "fs_rec.h"
|
||
#include "fat_rec.h"
|
||
|
||
//
|
||
// The local debug trace level
|
||
//
|
||
|
||
#define Dbg (FSREC_DEBUG_LEVEL_FAT)
|
||
|
||
#ifdef ALLOC_PRAGMA
|
||
#pragma alloc_text(PAGE,FatRecFsControl)
|
||
#pragma alloc_text(PAGE,IsFatVolume)
|
||
#pragma alloc_text(PAGE,UnpackBiosParameterBlock)
|
||
#endif // ALLOC_PRAGMA
|
||
|
||
|
||
NTSTATUS
|
||
FatRecFsControl(
|
||
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;
|
||
UNICODE_STRING driverName;
|
||
ULONG bytesPerSector;
|
||
BOOLEAN isDeviceFailure = FALSE;
|
||
|
||
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 a FAT 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 FAT file system.
|
||
//
|
||
|
||
status = STATUS_UNRECOGNIZED_VOLUME;
|
||
|
||
//
|
||
// Attempt to determine whether or not the target volume being mounted
|
||
// is a FAT volume. Note that if an error occurs, and this is a floppy
|
||
// drive, and the error occurred on the actual read from the device,
|
||
// then the FAT file system will actually be loaded to handle the
|
||
// problem since this driver is a place holder and does not need to
|
||
// know all of the protocols for handling floppy errors.
|
||
//
|
||
|
||
targetDevice = irpSp->Parameters.MountVolume.DeviceObject;
|
||
|
||
//
|
||
// First retrieve the sector size for this media.
|
||
//
|
||
|
||
if (FsRecGetDeviceSectorSize( targetDevice,
|
||
&bytesPerSector )) {
|
||
|
||
byteOffset.QuadPart = 0;
|
||
buffer = NULL;
|
||
|
||
if (FsRecReadBlock( targetDevice,
|
||
&byteOffset,
|
||
512,
|
||
bytesPerSector,
|
||
&buffer,
|
||
&isDeviceFailure ) &&
|
||
IsFatVolume( buffer )) {
|
||
|
||
status = STATUS_FS_DRIVER_REQUIRED;
|
||
|
||
}
|
||
|
||
if (buffer != NULL) {
|
||
ExFreePool( buffer );
|
||
}
|
||
|
||
} else {
|
||
|
||
//
|
||
// Devices that can't get us this much ...
|
||
//
|
||
|
||
isDeviceFailure = TRUE;
|
||
}
|
||
|
||
//
|
||
// See if we should make the real filesystem take a shot at a wacky floppy.
|
||
//
|
||
|
||
if (isDeviceFailure) {
|
||
if (targetDevice->Characteristics & FILE_FLOPPY_DISKETTE) {
|
||
status = STATUS_FS_DRIVER_REQUIRED;
|
||
}
|
||
}
|
||
|
||
break;
|
||
|
||
case IRP_MN_LOAD_FILE_SYSTEM:
|
||
|
||
status = FsRecLoadFileSystem( DeviceObject,
|
||
L"\\Registry\\Machine\\System\\CurrentControlSet\\Services\\Fastfat" );
|
||
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;
|
||
}
|
||
|
||
|
||
BOOLEAN
|
||
IsFatVolume(
|
||
IN PPACKED_BOOT_SECTOR Buffer
|
||
)
|
||
|
||
/*++
|
||
|
||
Routine Description:
|
||
|
||
This routine looks at the buffer passed in which contains the FAT boot
|
||
sector and determines whether or not it represents an actual FAT boot
|
||
sector.
|
||
|
||
Arguments:
|
||
|
||
Buffer - Pointer to buffer containing potential boot block.
|
||
|
||
Return Value:
|
||
|
||
The function returns TRUE if the buffer contains a recognizable FAT boot
|
||
sector, otherwise it returns FALSE.
|
||
|
||
--*/
|
||
|
||
{
|
||
BIOS_PARAMETER_BLOCK bios;
|
||
BOOLEAN result;
|
||
|
||
PAGED_CODE();
|
||
|
||
//
|
||
// Begin by unpacking the Bios Parameter Block that is packed in the boot
|
||
// sector so that it can be examined without incurring alignment faults.
|
||
//
|
||
|
||
UnpackBiosParameterBlock( &Buffer->PackedBpb, &bios );
|
||
|
||
//
|
||
// Assume that the sector represents a FAT boot block and then determine
|
||
// whether or not it really does.
|
||
//
|
||
|
||
result = TRUE;
|
||
|
||
if (bios.Sectors) {
|
||
bios.LargeSectors = 0;
|
||
}
|
||
|
||
// FMR Jul.11.1994 NaokiM - Fujitsu -
|
||
// FMR boot sector has 'IPL1' string at the beginnig.
|
||
|
||
if (Buffer->Jump[0] != 0x49 && /* FMR */
|
||
Buffer->Jump[0] != 0xe9 &&
|
||
Buffer->Jump[0] != 0xeb) {
|
||
|
||
result = FALSE;
|
||
|
||
|
||
// FMR Jul.11.1994 NaokiM - Fujitsu -
|
||
// Sector size of FMR partition is 2048.
|
||
|
||
} else if (bios.BytesPerSector != 128 &&
|
||
bios.BytesPerSector != 256 &&
|
||
bios.BytesPerSector != 512 &&
|
||
bios.BytesPerSector != 1024 &&
|
||
bios.BytesPerSector != 2048 && /* FMR */
|
||
bios.BytesPerSector != 4096) {
|
||
|
||
result = FALSE;
|
||
|
||
} else if (bios.SectorsPerCluster != 1 &&
|
||
bios.SectorsPerCluster != 2 &&
|
||
bios.SectorsPerCluster != 4 &&
|
||
bios.SectorsPerCluster != 8 &&
|
||
bios.SectorsPerCluster != 16 &&
|
||
bios.SectorsPerCluster != 32 &&
|
||
bios.SectorsPerCluster != 64 &&
|
||
bios.SectorsPerCluster != 128) {
|
||
|
||
result = FALSE;
|
||
|
||
} else if (!bios.ReservedSectors) {
|
||
|
||
result = FALSE;
|
||
|
||
} else if (!bios.Fats) {
|
||
|
||
result = FALSE;
|
||
|
||
//
|
||
// Prior to DOS 3.2 might contains value in both of Sectors and
|
||
// Sectors Large.
|
||
//
|
||
} else if (!bios.Sectors && !bios.LargeSectors) {
|
||
|
||
result = FALSE;
|
||
|
||
// FMR Jul.11.1994 NaokiM - Fujitsu -
|
||
// 1. Media descriptor of FMR partitions is 0xfa.
|
||
// 2. Media descriptor of partitions formated by FMR OS/2 is 0x00.
|
||
// 3. Media descriptor of floppy disks formated by FMR DOS is 0x01.
|
||
|
||
} else if (bios.Media != 0x00 && /* FMR */
|
||
bios.Media != 0x01 && /* FMR */
|
||
bios.Media != 0xf0 &&
|
||
bios.Media != 0xf8 &&
|
||
bios.Media != 0xf9 &&
|
||
bios.Media != 0xfa && /* FMR */
|
||
bios.Media != 0xfb &&
|
||
bios.Media != 0xfc &&
|
||
bios.Media != 0xfd &&
|
||
bios.Media != 0xfe &&
|
||
bios.Media != 0xff) {
|
||
|
||
result = FALSE;
|
||
|
||
} else if (bios.SectorsPerFat != 0 && bios.RootEntries == 0) {
|
||
|
||
result = FALSE;
|
||
}
|
||
|
||
return result;
|
||
}
|
||
|
||
|
||
VOID
|
||
UnpackBiosParameterBlock(
|
||
IN PPACKED_BIOS_PARAMETER_BLOCK Bios,
|
||
OUT PBIOS_PARAMETER_BLOCK UnpackedBios
|
||
)
|
||
|
||
/*++
|
||
|
||
Routine Description:
|
||
|
||
This routine copies a packed Bios Parameter Block to an unpacked Bios
|
||
Parameter Block.
|
||
|
||
Arguments:
|
||
|
||
Bios - Pointer to the packed Bios Parameter Block.
|
||
|
||
UnpackedBios - Pointer to the unpacked Bios Parameter Block.
|
||
|
||
Return Value:
|
||
|
||
None.
|
||
|
||
--*/
|
||
|
||
{
|
||
PAGED_CODE();
|
||
|
||
//
|
||
// Unpack the Bios Parameter Block.
|
||
//
|
||
|
||
CopyUchar2( &UnpackedBios->BytesPerSector, &Bios->BytesPerSector[0] );
|
||
CopyUchar2( &UnpackedBios->BytesPerSector, &Bios->BytesPerSector[0] );
|
||
CopyUchar1( &UnpackedBios->SectorsPerCluster, &Bios->SectorsPerCluster[0] );
|
||
CopyUchar2( &UnpackedBios->ReservedSectors, &Bios->ReservedSectors[0] );
|
||
CopyUchar1( &UnpackedBios->Fats, &Bios->Fats[0] );
|
||
CopyUchar2( &UnpackedBios->RootEntries, &Bios->RootEntries[0] );
|
||
CopyUchar2( &UnpackedBios->Sectors, &Bios->Sectors[0] );
|
||
CopyUchar1( &UnpackedBios->Media, &Bios->Media[0] );
|
||
CopyUchar2( &UnpackedBios->SectorsPerFat, &Bios->SectorsPerFat[0] );
|
||
CopyUchar2( &UnpackedBios->SectorsPerTrack, &Bios->SectorsPerTrack[0] );
|
||
CopyUchar2( &UnpackedBios->Heads, &Bios->Heads[0] );
|
||
CopyUchar4( &UnpackedBios->HiddenSectors, &Bios->HiddenSectors[0] );
|
||
CopyUchar4( &UnpackedBios->LargeSectors, &Bios->LargeSectors[0] );
|
||
}
|