lib/ext2fs/openfs.c

   1 /*
   2  * openfs.c --- open an ext2 filesystem
   3  *
   4  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Library
   8  * General Public License, version 2.
   9  * %End-Header%
  10  */
  11
  12 #include "config.h"
  13 #include <stdio.h>
  14 #include <string.h>
  15 #if HAVE_UNISTD_H
  16 #include <unistd.h>
  17 #endif
  18 #include <fcntl.h>
  19 #include <time.h>
  20 #if HAVE_SYS_STAT_H
  21 #include <sys/stat.h>
  22 #endif
  23 #if HAVE_SYS_TYPES_H
  24 #include <sys/types.h>
  25 #endif
  26 #ifdef HAVE_ERRNO_H
  27 #include <errno.h>
  28 #endif
  29
  30 #include "ext2_fs.h"
  31
  32
  33 #include "ext2fs.h"
  34 #include "e2image.h"
  35
  36 blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs, blk64_t group_block,
  37                                      dgrp_t i)
  38 {
  39         int     bg;
  40         int     has_super = 0, group_zero_adjust = 0;
  41         blk64_t ret_blk;
  42
  43         /*
  44          * On a bigalloc FS with 1K blocks, block 0 is reserved for non-ext4
  45          * stuff, so adjust for that if we're being asked for group 0.
  46          */
  47         if (i == 0 && fs->blocksize == 1024 && EXT2FS_CLUSTER_RATIO(fs) > 1)
  48                 group_zero_adjust = 1;
  49
  50         if (!ext2fs_has_feature_meta_bg(fs->super) ||
  51             (i < fs->super->s_first_meta_bg))
  52                 return group_block + i + 1 + group_zero_adjust;
  53
  54         bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
  55         if (ext2fs_bg_has_super(fs, bg))
  56                 has_super = 1;
  57         ret_blk = ext2fs_group_first_block2(fs, bg);
  58         /*
  59          * If group_block is not the normal value, we're trying to use
  60          * the backup group descriptors and superblock --- so use the
  61          * alternate location of the second block group in the
  62          * metablock group.  Ideally we should be testing each bg
  63          * descriptor block individually for correctness, but we don't
  64          * have the infrastructure in place to do that.
  65          */
  66         if (group_block != fs->super->s_first_data_block &&
  67             ((ret_blk + has_super + fs->super->s_blocks_per_group) <
  68              ext2fs_blocks_count(fs->super))) {
  69                 ret_blk += fs->super->s_blocks_per_group;
  70
  71                 /*
  72                  * If we're going to jump forward a block group, make sure
  73                  * that we adjust has_super to account for the next group's
  74                  * backup superblock (or lack thereof).
  75                  */
  76                 if (ext2fs_bg_has_super(fs, bg + 1))
  77                         has_super = 1;
  78                 else
  79                         has_super = 0;
  80         }
  81         return ret_blk + has_super + group_zero_adjust;
  82 }
  83
  84 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  85 {
  86         return ext2fs_descriptor_block_loc2(fs, group_block, i);
  87 }
  88
  89 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  90                       unsigned int block_size, io_manager manager,
  91                       ext2_filsys *ret_fs)
  92 {
  93         return ext2fs_open2(name, 0, flags, superblock, block_size,
  94                             manager, ret_fs);
  95 }
  96
  97 /*
  98  *  Note: if superblock is non-zero, block-size must also be non-zero.
  99  *      Superblock and block_size can be zero to use the default size.
 100  *
 101  * Valid flags for ext2fs_open()
 102  *
 103  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
 104  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
 105  *                              features aren't supported.
 106  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
 107  *      EXT2_FLAG_SKIP_MMP - Open without multi-mount protection check.
 108  *      EXT2_FLAG_64BITS - Allow 64-bit bitfields (needed for large
 109  *                              filesystems)
 110  */
 111 errcode_t ext2fs_open2(const char *name, const char *io_options,
 112                        int flags, int superblock,
 113                        unsigned int block_size, io_manager manager,
 114                        ext2_filsys *ret_fs)
 115 {
 116         ext2_filsys     fs;
 117         errcode_t       retval;
 118         unsigned long   i, first_meta_bg;
 119         __u32           features;
 120         unsigned int    blocks_per_group, io_flags;
 121         blk64_t         group_block, blk;
 122         char            *dest, *cp;
 123         int             group_zero_adjust = 0;
 124 #ifdef WORDS_BIGENDIAN
 125         unsigned int    groups_per_block;
 126         struct ext2_group_desc *gdp;
 127         int             j;
 128 #endif
 129
 130         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 131
 132         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 133         if (retval)
 134                 return retval;
 135
 136         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 137         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 138         fs->flags = flags;
 139         /* don't overwrite sb backups unless flag is explicitly cleared */
 140         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 141         fs->umask = 022;
 142         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 143         if (retval)
 144                 goto cleanup;
 145         strcpy(fs->device_name, name);
 146         cp = strchr(fs->device_name, '?');
 147         if (!io_options && cp) {
 148                 *cp++ = 0;
 149                 io_options = cp;
 150         }
 151
 152         io_flags = 0;
 153         if (flags & EXT2_FLAG_RW)
 154                 io_flags |= IO_FLAG_RW;
 155         if (flags & EXT2_FLAG_EXCLUSIVE)
 156                 io_flags |= IO_FLAG_EXCLUSIVE;
 157         if (flags & EXT2_FLAG_DIRECT_IO)
 158                 io_flags |= IO_FLAG_DIRECT_IO;
 159         retval = manager->open(fs->device_name, io_flags, &fs->io);
 160         if (retval)
 161                 goto cleanup;
 162         if (io_options &&
 163             (retval = io_channel_set_options(fs->io, io_options)))
 164                 goto cleanup;
 165         fs->image_io = fs->io;
 166         fs->io->app_data = fs;
 167         retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
 168         if (retval)
 169                 goto cleanup;
 170         if (flags & EXT2_FLAG_IMAGE_FILE) {
 171                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 172                                         &fs->image_header);
 173                 if (retval)
 174                         goto cleanup;
 175                 retval = io_channel_read_blk(fs->io, 0,
 176                                              -(int)sizeof(struct ext2_image_hdr),
 177                                              fs->image_header);
 178                 if (retval)
 179                         goto cleanup;
 180                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 181                         return EXT2_ET_MAGIC_E2IMAGE;
 182                 superblock = 1;
 183                 block_size = fs->image_header->fs_blocksize;
 184         }
 185
 186         /*
 187          * If the user specifies a specific block # for the
 188          * superblock, then he/she must also specify the block size!
 189          * Otherwise, read the master superblock located at offset
 190          * SUPERBLOCK_OFFSET from the start of the partition.
 191          *
 192          * Note: we only save a backup copy of the superblock if we
 193          * are reading the superblock from the primary superblock location.
 194          */
 195         if (superblock) {
 196                 if (!block_size) {
 197                         retval = EXT2_ET_INVALID_ARGUMENT;
 198                         goto cleanup;
 199                 }
 200                 io_channel_set_blksize(fs->io, block_size);
 201                 group_block = superblock;
 202                 fs->orig_super = 0;
 203         } else {
 204                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 205                 superblock = 1;
 206                 group_block = 0;
 207                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 208                 if (retval)
 209                         goto cleanup;
 210         }
 211         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 212                                      fs->super);
 213         if (retval)
 214                 goto cleanup;
 215         if (fs->orig_super)
 216                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 217
 218         if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
 219                 retval = 0;
 220                 if (!ext2fs_verify_csum_type(fs, fs->super))
 221                         retval = EXT2_ET_UNKNOWN_CSUM;
 222                 if (!ext2fs_superblock_csum_verify(fs, fs->super))
 223                         retval = EXT2_ET_SB_CSUM_INVALID;
 224         }
 225
 226 #ifdef WORDS_BIGENDIAN
 227         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 228         ext2fs_swap_super(fs->super);
 229 #else
 230         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 231                 retval = EXT2_ET_UNIMPLEMENTED;
 232                 goto cleanup;
 233         }
 234 #endif
 235
 236         if (fs->super->s_magic != EXT2_SUPER_MAGIC)
 237                 retval = EXT2_ET_BAD_MAGIC;
 238         if (retval)
 239                 goto cleanup;
 240
 241         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 242                 retval = EXT2_ET_REV_TOO_HIGH;
 243                 goto cleanup;
 244         }
 245
 246         /*
 247          * Check for feature set incompatibility
 248          */
 249         if (!(flags & EXT2_FLAG_FORCE)) {
 250                 features = fs->super->s_feature_incompat;
 251 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 252                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 253                         features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
 254 #endif
 255                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 256                         retval = EXT2_ET_UNSUPP_FEATURE;
 257                         goto cleanup;
 258                 }
 259
 260                 features = fs->super->s_feature_ro_compat;
 261 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 262                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 263                         features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
 264 #endif
 265                 if ((flags & EXT2_FLAG_RW) &&
 266                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 267                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 268                         goto cleanup;
 269                 }
 270
 271                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 272                     ext2fs_has_feature_journal_dev(fs->super)) {
 273                         retval = EXT2_ET_UNSUPP_FEATURE;
 274                         goto cleanup;
 275                 }
 276         }
 277
 278         if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
 279             EXT2_MAX_BLOCK_LOG_SIZE) {
 280                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 281                 goto cleanup;
 282         }
 283
 284         /*
 285          * bigalloc requires cluster-aware bitfield operations, which at the
 286          * moment means we need EXT2_FLAG_64BITS.
 287          */
 288         if (ext2fs_has_feature_bigalloc(fs->super) &&
 289             !(flags & EXT2_FLAG_64BITS)) {
 290                 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
 291                 goto cleanup;
 292         }
 293
 294         if (!ext2fs_has_feature_bigalloc(fs->super) &&
 295             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 296                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 297                 goto cleanup;
 298         }
 299         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 300         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 301                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 302                 goto cleanup;
 303         }
 304
 305         /* Enforce the block group descriptor size */
 306         if (ext2fs_has_feature_64bit(fs->super)) {
 307                 if (fs->super->s_desc_size < EXT2_MIN_DESC_SIZE_64BIT) {
 308                         retval = EXT2_ET_BAD_DESC_SIZE;
 309                         goto cleanup;
 310                 }
 311         } else {
 312                 if (fs->super->s_desc_size &&
 313                     fs->super->s_desc_size != EXT2_MIN_DESC_SIZE) {
 314                         retval = EXT2_ET_BAD_DESC_SIZE;
 315                         goto cleanup;
 316                 }
 317         }
 318
 319         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 320                 fs->super->s_log_block_size;
 321         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 322             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 323                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 324                 goto cleanup;
 325         }
 326         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 327                                        EXT2_INODE_SIZE(fs->super) +
 328                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 329                                       EXT2_BLOCK_SIZE(fs->super));
 330         if (block_size) {
 331                 if (block_size != fs->blocksize) {
 332                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 333                         goto cleanup;
 334                 }
 335         }
 336         /*
 337          * Set the blocksize to the filesystem's blocksize.
 338          */
 339         io_channel_set_blksize(fs->io, fs->blocksize);
 340
 341         /*
 342          * If this is an external journal device, don't try to read
 343          * the group descriptors, because they're not there.
 344          */
 345         if (ext2fs_has_feature_journal_dev(fs->super)) {
 346                 fs->group_desc_count = 0;
 347                 *ret_fs = fs;
 348                 return 0;
 349         }
 350
 351         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 352                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 353                 goto cleanup;
 354         }
 355         /* Precompute the FS UUID to seed other checksums */
 356         ext2fs_init_csum_seed(fs);
 357
 358         /*
 359          * Read group descriptors
 360          */
 361         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 362         if (blocks_per_group == 0 ||
 363             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 364             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 365            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 366            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 367                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 368                 goto cleanup;
 369         }
 370         fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 371                                                  fs->super->s_first_data_block,
 372                                                  blocks_per_group);
 373         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 374             fs->super->s_inodes_count) {
 375                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 376                 goto cleanup;
 377         }
 378         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 379                                           EXT2_DESC_PER_BLOCK(fs->super));
 380         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 381                                 &fs->group_desc);
 382         if (retval)
 383                 goto cleanup;
 384         if (!group_block)
 385                 group_block = fs->super->s_first_data_block;
 386         /*
 387          * On a FS with a 1K blocksize, block 0 is reserved for bootloaders
 388          * so we must increment block numbers to any group 0 items.
 389          *
 390          * However, we cannot touch group_block directly because in the meta_bg
 391          * case, the ext2fs_descriptor_block_loc2() function will interpret
 392          * group_block != s_first_data_block to mean that we want to access the
 393          * backup group descriptors.  This is not what we want if the caller
 394          * set superblock == 0 (i.e. auto-detect the superblock), which is
 395          * what's going on here.
 396          */
 397         if (group_block == 0 && fs->blocksize == 1024)
 398                 group_zero_adjust = 1;
 399         dest = (char *) fs->group_desc;
 400 #ifdef WORDS_BIGENDIAN
 401         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 402 #endif
 403         if (ext2fs_has_feature_meta_bg(fs->super)) {
 404                 first_meta_bg = fs->super->s_first_meta_bg;
 405                 if (first_meta_bg > fs->desc_blocks)
 406                         first_meta_bg = fs->desc_blocks;
 407         } else
 408                 first_meta_bg = fs->desc_blocks;
 409         if (first_meta_bg) {
 410                 retval = io_channel_read_blk(fs->io, group_block +
 411                                              group_zero_adjust + 1,
 412                                              first_meta_bg, dest);
 413                 if (retval)
 414                         goto cleanup;
 415 #ifdef WORDS_BIGENDIAN
 416                 gdp = (struct ext2_group_desc *) dest;
 417                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 418                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 419                         ext2fs_swap_group_desc2(fs, gdp);
 420                 }
 421 #endif
 422                 dest += fs->blocksize*first_meta_bg;
 423         }
 424         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 425                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 426                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 427                 if (retval)
 428                         goto cleanup;
 429 #ifdef WORDS_BIGENDIAN
 430                 for (j=0; j < groups_per_block; j++) {
 431                         gdp = ext2fs_group_desc(fs, fs->group_desc,
 432                                                 i * groups_per_block + j);
 433                         ext2fs_swap_group_desc2(fs, gdp);
 434                 }
 435 #endif
 436                 dest += fs->blocksize;
 437         }
 438
 439         fs->stride = fs->super->s_raid_stride;
 440
 441         /*
 442          * If recovery is from backup superblock, Clear _UNININT flags &
 443          * reset bg_itable_unused to zero
 444          */
 445         if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
 446                 dgrp_t group;
 447
 448                 for (group = 0; group < fs->group_desc_count; group++) {
 449                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 450                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 451                         ext2fs_bg_itable_unused_set(fs, group, 0);
 452                         /* The checksum will be reset later, but fix it here
 453                          * anyway to avoid printing a lot of spurious errors. */
 454                         ext2fs_group_desc_csum_set(fs, group);
 455                 }
 456                 if (fs->flags & EXT2_FLAG_RW)
 457                         ext2fs_mark_super_dirty(fs);
 458         }
 459
 460         if (ext2fs_has_feature_mmp(fs->super) &&
 461             !(flags & EXT2_FLAG_SKIP_MMP) &&
 462             (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
 463                 retval = ext2fs_mmp_start(fs);
 464                 if (retval) {
 465                         fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
 466                         ext2fs_mmp_stop(fs);
 467                         goto cleanup;
 468                 }
 469         }
 470
 471         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 472         *ret_fs = fs;
 473
 474         return 0;
 475 cleanup:
 476         if (!(flags & EXT2_FLAG_NOFREE_ON_ERROR)) {
 477                 ext2fs_free(fs);
 478                 fs = NULL;
 479         }
 480         *ret_fs = fs;
 481         return retval;
 482 }
 483
 484 /*
 485  * Set/get the filesystem data I/O channel.
 486  *
 487  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 488  */
 489 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 490 {
 491         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 492                 return EXT2_ET_NOT_IMAGE_FILE;
 493         if (old_io) {
 494                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 495         }
 496         return 0;
 497 }
 498
 499 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 500 {
 501         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 502                 return EXT2_ET_NOT_IMAGE_FILE;
 503         fs->io = new_io ? new_io : fs->image_io;
 504         return 0;
 505 }
 506
 507 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 508 {
 509         errcode_t err;
 510
 511         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 512                 return EXT2_ET_NOT_IMAGE_FILE;
 513         err = io_channel_set_blksize(new_io, fs->blocksize);
 514         if (err)
 515                 return err;
 516         if ((new_io == fs->image_io) || (new_io == fs->io))
 517                 return 0;
 518         if ((fs->image_io != fs->io) &&
 519             fs->image_io)
 520                 io_channel_close(fs->image_io);
 521         if (fs->io)
 522                 io_channel_close(fs->io);
 523         fs->io = fs->image_io = new_io;
 524         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 525                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 526         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 527         return 0;
 528 }