test: fat_rec.c Source File

00001 /*++ 00002 00003 Copyright (c) 1992 Microsoft Corporation 00004 00005 Module Name: 00006 00007 fat_rec.c 00008 00009 Abstract: 00010 00011 This module contains the mini-file system recognizer for FAT. 00012 00013 Author: 00014 00015 Darryl E. Havens (darrylh) 8-dec-1992 00016 00017 Environment: 00018 00019 Kernel mode, local to I/O system 00020 00021 Revision History: 00022 00023 00024 --*/ 00025 00026 #include "fs_rec.h" 00027 #include "fat_rec.h" 00028 00029 // 00030 // The local debug trace level 00031 // 00032 00033 #define Dbg (FSREC_DEBUG_LEVEL_FAT) 00034 00035 #ifdef ALLOC_PRAGMA 00036 #pragma alloc_text(PAGE,FatRecFsControl) 00037 #pragma alloc_text(PAGE,IsFatVolume) 00038 #pragma alloc_text(PAGE,UnpackBiosParameterBlock) 00039 #endif // ALLOC_PRAGMA 00040 00041 00042 NTSTATUS 00043 FatRecFsControl( 00044 IN PDEVICE_OBJECT DeviceObject, 00045 IN PIRP Irp 00046 ) 00047 00048 /*++ 00049 00050 Routine Description: 00051 00052 This function performs the mount and driver reload functions for this mini- 00053 file system recognizer driver. 00054 00055 Arguments: 00056 00057 DeviceObject - Pointer to this driver's device object. 00058 00059 Irp - Pointer to the I/O Request Packet (IRP) representing the function to 00060 be performed. 00061 00062 Return Value: 00063 00064 The function value is the final status of the operation. 00065 00066 00067 --*/ 00068 00069 { 00070 NTSTATUS status; 00071 PIO_STACK_LOCATION irpSp; 00072 PDEVICE_EXTENSION deviceExtension; 00073 PDEVICE_OBJECT targetDevice; 00074 PPACKED_BOOT_SECTOR buffer; 00075 LARGE_INTEGER byteOffset; 00076 UNICODE_STRING driverName; 00077 ULONG bytesPerSector; 00078 BOOLEAN isDeviceFailure = FALSE; 00079 00080 PAGED_CODE(); 00081 00082 // 00083 // Begin by determining what function that is to be performed. 00084 // 00085 00086 deviceExtension = (PDEVICE_EXTENSION) DeviceObject->DeviceExtension; 00087 irpSp = IoGetCurrentIrpStackLocation( Irp ); 00088 00089 switch ( irpSp->MinorFunction ) { 00090 00091 case IRP_MN_MOUNT_VOLUME: 00092 00093 // 00094 // Attempt to mount a volume: Determine whether or not the volume in 00095 // question is a FAT volume and, if so, let the I/O system know that it 00096 // is by returning a special status code so that this driver can get 00097 // called back to load the FAT file system. 00098 // 00099 00100 status = STATUS_UNRECOGNIZED_VOLUME; 00101 00102 // 00103 // Attempt to determine whether or not the target volume being mounted 00104 // is a FAT volume. Note that if an error occurs, and this is a floppy 00105 // drive, and the error occurred on the actual read from the device, 00106 // then the FAT file system will actually be loaded to handle the 00107 // problem since this driver is a place holder and does not need to 00108 // know all of the protocols for handling floppy errors. 00109 // 00110 00111 targetDevice = irpSp->Parameters.MountVolume.DeviceObject; 00112 00113 // 00114 // First retrieve the sector size for this media. 00115 // 00116 00117 if (FsRecGetDeviceSectorSize( targetDevice, 00118 &bytesPerSector )) { 00119 00120 byteOffset.QuadPart = 0; 00121 buffer = NULL; 00122 00123 if (FsRecReadBlock( targetDevice, 00124 &byteOffset, 00125 512, 00126 bytesPerSector, 00127 &buffer, 00128 &isDeviceFailure ) && 00129 IsFatVolume( buffer )) { 00130 00131 status = STATUS_FS_DRIVER_REQUIRED; 00132 00133 } 00134 00135 if (buffer != NULL) { 00136 ExFreePool( buffer ); 00137 } 00138 00139 } else { 00140 00141 // 00142 // Devices that can't get us this much ... 00143 // 00144 00145 isDeviceFailure = TRUE; 00146 } 00147 00148 // 00149 // See if we should make the real filesystem take a shot at a wacky floppy. 00150 // 00151 00152 if (isDeviceFailure) { 00153 if (targetDevice->Characteristics & FILE_FLOPPY_DISKETTE) { 00154 status = STATUS_FS_DRIVER_REQUIRED; 00155 } 00156 } 00157 00158 break; 00159 00160 case IRP_MN_LOAD_FILE_SYSTEM: 00161 00162 status = FsRecLoadFileSystem( DeviceObject, 00163 L"\\Registry\\Machine\\System\\CurrentControlSet\\Services\\Fastfat" ); 00164 break; 00165 00166 default: 00167 status = STATUS_INVALID_DEVICE_REQUEST; 00168 00169 } 00170 00171 // 00172 // Finally, complete the request and return the same status code to the 00173 // caller. 00174 // 00175 00176 Irp->IoStatus.Status = status; 00177 IoCompleteRequest( Irp, IO_NO_INCREMENT ); 00178 00179 return status; 00180 } 00181 00182 00183 BOOLEAN 00184 IsFatVolume( 00185 IN PPACKED_BOOT_SECTOR Buffer 00186 ) 00187 00188 /*++ 00189 00190 Routine Description: 00191 00192 This routine looks at the buffer passed in which contains the FAT boot 00193 sector and determines whether or not it represents an actual FAT boot 00194 sector. 00195 00196 Arguments: 00197 00198 Buffer - Pointer to buffer containing potential boot block. 00199 00200 Return Value: 00201 00202 The function returns TRUE if the buffer contains a recognizable FAT boot 00203 sector, otherwise it returns FALSE. 00204 00205 --*/ 00206 00207 { 00208 BIOS_PARAMETER_BLOCK bios; 00209 BOOLEAN result; 00210 00211 PAGED_CODE(); 00212 00213 // 00214 // Begin by unpacking the Bios Parameter Block that is packed in the boot 00215 // sector so that it can be examined without incurring alignment faults. 00216 // 00217 00218 UnpackBiosParameterBlock( &Buffer->PackedBpb, &bios ); 00219 00220 // 00221 // Assume that the sector represents a FAT boot block and then determine 00222 // whether or not it really does. 00223 // 00224 00225 result = TRUE; 00226 00227 if (bios.Sectors) { 00228 bios.LargeSectors = 0; 00229 } 00230 00231 // FMR Jul.11.1994 NaokiM - Fujitsu - 00232 // FMR boot sector has 'IPL1' string at the beginnig. 00233 00234 if (Buffer->Jump[0] != 0x49 && /* FMR */ 00235 Buffer->Jump[0] != 0xe9 && 00236 Buffer->Jump[0] != 0xeb) { 00237 00238 result = FALSE; 00239 00240 00241 // FMR Jul.11.1994 NaokiM - Fujitsu - 00242 // Sector size of FMR partition is 2048. 00243 00244 } else if (bios.BytesPerSector != 128 && 00245 bios.BytesPerSector != 256 && 00246 bios.BytesPerSector != 512 && 00247 bios.BytesPerSector != 1024 && 00248 bios.BytesPerSector != 2048 && /* FMR */ 00249 bios.BytesPerSector != 4096) { 00250 00251 result = FALSE; 00252 00253 } else if (bios.SectorsPerCluster != 1 && 00254 bios.SectorsPerCluster != 2 && 00255 bios.SectorsPerCluster != 4 && 00256 bios.SectorsPerCluster != 8 && 00257 bios.SectorsPerCluster != 16 && 00258 bios.SectorsPerCluster != 32 && 00259 bios.SectorsPerCluster != 64 && 00260 bios.SectorsPerCluster != 128) { 00261 00262 result = FALSE; 00263 00264 } else if (!bios.ReservedSectors) { 00265 00266 result = FALSE; 00267 00268 } else if (!bios.Fats) { 00269 00270 result = FALSE; 00271 00272 // 00273 // Prior to DOS 3.2 might contains value in both of Sectors and 00274 // Sectors Large. 00275 // 00276 } else if (!bios.Sectors && !bios.LargeSectors) { 00277 00278 result = FALSE; 00279 00280 // FMR Jul.11.1994 NaokiM - Fujitsu - 00281 // 1. Media descriptor of FMR partitions is 0xfa. 00282 // 2. Media descriptor of partitions formated by FMR OS/2 is 0x00. 00283 // 3. Media descriptor of floppy disks formated by FMR DOS is 0x01. 00284 00285 } else if (bios.Media != 0x00 && /* FMR */ 00286 bios.Media != 0x01 && /* FMR */ 00287 bios.Media != 0xf0 && 00288 bios.Media != 0xf8 && 00289 bios.Media != 0xf9 && 00290 bios.Media != 0xfa && /* FMR */ 00291 bios.Media != 0xfb && 00292 bios.Media != 0xfc && 00293 bios.Media != 0xfd && 00294 bios.Media != 0xfe && 00295 bios.Media != 0xff) { 00296 00297 result = FALSE; 00298 00299 } else if (bios.SectorsPerFat != 0 && bios.RootEntries == 0) { 00300 00301 result = FALSE; 00302 } 00303 00304 return result; 00305 } 00306 00307 00308 VOID 00309 UnpackBiosParameterBlock( 00310 IN PPACKED_BIOS_PARAMETER_BLOCK Bios, 00311 OUT PBIOS_PARAMETER_BLOCK UnpackedBios 00312 ) 00313 00314 /*++ 00315 00316 Routine Description: 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 }