fat_rec.c File Reference

#include "fs_rec.h"
#include "fat_rec.h"

Go to the source code of this file.

Defines
#define	Dbg   (FSREC_DEBUG_LEVEL_FAT)
Functions
NTSTATUS	FatRecFsControl (IN PDEVICE_OBJECT DeviceObject, IN PIRP Irp)
BOOLEAN	IsFatVolume (IN PPACKED_BOOT_SECTOR Buffer)
VOID	UnpackBiosParameterBlock (IN PPACKED_BIOS_PARAMETER_BLOCK Bios, OUT PBIOS_PARAMETER_BLOCK UnpackedBios)

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Define Documentation

#define Dbg   (FSREC_DEBUG_LEVEL_FAT)

Definition at line 33 of file fat_rec.c.

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Function Documentation

NTSTATUS FatRecFsControl (  IN PDEVICE_OBJECT  DeviceObject, IN PIRP  Irp )

Definition at line 43 of file fat_rec.c. References _DEVICE_OBJECT::Characteristics, ExFreePool(), FALSE, FsRecGetDeviceSectorSize(), FsRecLoadFileSystem(), FsRecReadBlock(), IO_NO_INCREMENT, IoCompleteRequest, IoGetCurrentIrpStackLocation, _IRP::IoStatus, Irp, IRP_MN_LOAD_FILE_SYSTEM, IRP_MN_MOUNT_VOLUME, IsFatVolume(), L, _IO_STACK_LOCATION::MinorFunction, NTSTATUS(), NULL, PAGED_CODE, _IO_STACK_LOCATION::Parameters, PPACKED_BOOT_SECTOR, and TRUE. Referenced by FsRecFsControl(). : 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  )

Definition at line 184 of file fat_rec.c. References Buffer, BIOS_PARAMETER_BLOCK::BytesPerSector, FALSE, BIOS_PARAMETER_BLOCK::Fats, BIOS_PARAMETER_BLOCK::LargeSectors, BIOS_PARAMETER_BLOCK::Media, PAGED_CODE, BIOS_PARAMETER_BLOCK::ReservedSectors, BIOS_PARAMETER_BLOCK::RootEntries, BIOS_PARAMETER_BLOCK::Sectors, BIOS_PARAMETER_BLOCK::SectorsPerCluster, BIOS_PARAMETER_BLOCK::SectorsPerFat, TRUE, and UnpackBiosParameterBlock(). Referenced by FatRecFsControl(). : 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 )

Definition at line 309 of file fat_rec.c. References CopyUchar1, CopyUchar2, CopyUchar4, PAGED_CODE, PBIOS_PARAMETER_BLOCK, and PPACKED_BIOS_PARAMETER_BLOCK. Referenced by IsFatVolume(). 00316 : 00317 00318 This routine copies a packed Bios Parameter Block to an unpacked Bios 00319 Parameter Block. 00320 00321 Arguments: 00322 00323 Bios - Pointer to the packed Bios Parameter Block. 00324 00325 UnpackedBios - Pointer to the unpacked Bios Parameter Block. 00326 00327 Return Value: 00328 00329 None. 00330 00331 --*/ 00332 00333 { 00334 PAGED_CODE(); 00335 00336 // 00337 // Unpack the Bios Parameter Block. 00338 // 00339 00340 CopyUchar2( &UnpackedBios->BytesPerSector, &Bios->BytesPerSector[0] ); 00341 CopyUchar2( &UnpackedBios->BytesPerSector, &Bios->BytesPerSector[0] ); 00342 CopyUchar1( &UnpackedBios->SectorsPerCluster, &Bios->SectorsPerCluster[0] ); 00343 CopyUchar2( &UnpackedBios->ReservedSectors, &Bios->ReservedSectors[0] ); 00344 CopyUchar1( &UnpackedBios->Fats, &Bios->Fats[0] ); 00345 CopyUchar2( &UnpackedBios->RootEntries, &Bios->RootEntries[0] ); 00346 CopyUchar2( &UnpackedBios->Sectors, &Bios->Sectors[0] ); 00347 CopyUchar1( &UnpackedBios->Media, &Bios->Media[0] ); 00348 CopyUchar2( &UnpackedBios->SectorsPerFat, &Bios->SectorsPerFat[0] ); 00349 CopyUchar2( &UnpackedBios->SectorsPerTrack, &Bios->SectorsPerTrack[0] ); 00350 CopyUchar2( &UnpackedBios->Heads, &Bios->Heads[0] ); 00351 CopyUchar4( &UnpackedBios->HiddenSectors, &Bios->HiddenSectors[0] ); 00352 CopyUchar4( &UnpackedBios->LargeSectors, &Bios->LargeSectors[0] ); 00353 } }

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