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         int             inode_size;
 125         __u64           groups_cnt;
 126 #ifdef WORDS_BIGENDIAN
 127         unsigned int    groups_per_block;
 128         struct ext2_group_desc *gdp;
 129         int             j;
 130 #endif
 131
 132         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 133
 134         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 135         if (retval)
 136                 return retval;
 137
 138         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 139         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 140         fs->flags = flags;
 141         /* don't overwrite sb backups unless flag is explicitly cleared */
 142         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 143         fs->umask = 022;
 144         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 145         if (retval)
 146                 goto cleanup;
 147         strcpy(fs->device_name, name);
 148         cp = strchr(fs->device_name, '?');
 149         if (!io_options && cp) {
 150                 *cp++ = 0;
 151                 io_options = cp;
 152         }
 153
 154         io_flags = 0;
 155         if (flags & EXT2_FLAG_RW)
 156                 io_flags |= IO_FLAG_RW;
 157         if (flags & EXT2_FLAG_EXCLUSIVE)
 158                 io_flags |= IO_FLAG_EXCLUSIVE;
 159         if (flags & EXT2_FLAG_DIRECT_IO)
 160                 io_flags |= IO_FLAG_DIRECT_IO;
 161         retval = manager->open(fs->device_name, io_flags, &fs->io);
 162         if (retval)
 163                 goto cleanup;
 164         if (io_options &&
 165             (retval = io_channel_set_options(fs->io, io_options)))
 166                 goto cleanup;
 167         fs->image_io = fs->io;
 168         fs->io->app_data = fs;
 169         retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
 170         if (retval)
 171                 goto cleanup;
 172         if (flags & EXT2_FLAG_IMAGE_FILE) {
 173                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 174                                         &fs->image_header);
 175                 if (retval)
 176                         goto cleanup;
 177                 retval = io_channel_read_blk(fs->io, 0,
 178                                              -(int)sizeof(struct ext2_image_hdr),
 179                                              fs->image_header);
 180                 if (retval)
 181                         goto cleanup;
 182                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 183                         return EXT2_ET_MAGIC_E2IMAGE;
 184                 superblock = 1;
 185                 block_size = fs->image_header->fs_blocksize;
 186         }
 187
 188         /*
 189          * If the user specifies a specific block # for the
 190          * superblock, then he/she must also specify the block size!
 191          * Otherwise, read the master superblock located at offset
 192          * SUPERBLOCK_OFFSET from the start of the partition.
 193          *
 194          * Note: we only save a backup copy of the superblock if we
 195          * are reading the superblock from the primary superblock location.
 196          */
 197         if (superblock) {
 198                 if (!block_size) {
 199                         retval = EXT2_ET_INVALID_ARGUMENT;
 200                         goto cleanup;
 201                 }
 202                 io_channel_set_blksize(fs->io, block_size);
 203                 group_block = superblock;
 204                 fs->orig_super = 0;
 205         } else {
 206                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 207                 superblock = 1;
 208                 group_block = 0;
 209                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 210                 if (retval)
 211                         goto cleanup;
 212         }
 213         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 214                                      fs->super);
 215         if (retval)
 216                 goto cleanup;
 217         if (fs->orig_super)
 218                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 219
 220         if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
 221                 retval = 0;
 222                 if (!ext2fs_verify_csum_type(fs, fs->super))
 223                         retval = EXT2_ET_UNKNOWN_CSUM;
 224                 if (!ext2fs_superblock_csum_verify(fs, fs->super))
 225                         retval = EXT2_ET_SB_CSUM_INVALID;
 226         }
 227
 228 #ifdef WORDS_BIGENDIAN
 229         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 230         ext2fs_swap_super(fs->super);
 231 #else
 232         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 233                 retval = EXT2_ET_UNIMPLEMENTED;
 234                 goto cleanup;
 235         }
 236 #endif
 237
 238         if (fs->super->s_magic != EXT2_SUPER_MAGIC)
 239                 retval = EXT2_ET_BAD_MAGIC;
 240         if (retval)
 241                 goto cleanup;
 242
 243         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 244                 retval = EXT2_ET_REV_TOO_HIGH;
 245                 goto cleanup;
 246         }
 247
 248         /*
 249          * Check for feature set incompatibility
 250          */
 251         if (!(flags & EXT2_FLAG_FORCE)) {
 252                 features = fs->super->s_feature_incompat;
 253 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 254                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 255                         features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
 256 #endif
 257                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 258                         retval = EXT2_ET_UNSUPP_FEATURE;
 259                         goto cleanup;
 260                 }
 261
 262                 features = fs->super->s_feature_ro_compat;
 263 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 264                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 265                         features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
 266 #endif
 267                 if ((flags & EXT2_FLAG_RW) &&
 268                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 269                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 270                         goto cleanup;
 271                 }
 272
 273                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 274                     ext2fs_has_feature_journal_dev(fs->super)) {
 275                         retval = EXT2_ET_UNSUPP_FEATURE;
 276                         goto cleanup;
 277                 }
 278         }
 279
 280         if (fs->super->s_log_block_size >
 281             (unsigned) (EXT2_MAX_BLOCK_LOG_SIZE - EXT2_MIN_BLOCK_LOG_SIZE)) {
 282                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 283                 goto cleanup;
 284         }
 285
 286         /*
 287          * bigalloc requires cluster-aware bitfield operations, which at the
 288          * moment means we need EXT2_FLAG_64BITS.
 289          */
 290         if (ext2fs_has_feature_bigalloc(fs->super) &&
 291             !(flags & EXT2_FLAG_64BITS)) {
 292                 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
 293                 goto cleanup;
 294         }
 295
 296         if (!ext2fs_has_feature_bigalloc(fs->super) &&
 297             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 298                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 299                 goto cleanup;
 300         }
 301         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 302         inode_size = EXT2_INODE_SIZE(fs->super);
 303         if ((inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 304             (inode_size > fs->blocksize) ||
 305             (inode_size & (inode_size - 1))) {
 306                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 307                 goto cleanup;
 308         }
 309
 310         /* Enforce the block group descriptor size */
 311         if (ext2fs_has_feature_64bit(fs->super)) {
 312                 if (fs->super->s_desc_size < EXT2_MIN_DESC_SIZE_64BIT) {
 313                         retval = EXT2_ET_BAD_DESC_SIZE;
 314                         goto cleanup;
 315                 }
 316         } else {
 317                 if (fs->super->s_desc_size &&
 318                     fs->super->s_desc_size != EXT2_MIN_DESC_SIZE) {
 319                         retval = EXT2_ET_BAD_DESC_SIZE;
 320                         goto cleanup;
 321                 }
 322         }
 323
 324         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 325                 fs->super->s_log_block_size;
 326         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 327             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 328                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 329                 goto cleanup;
 330         }
 331         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 332                                        EXT2_INODE_SIZE(fs->super) +
 333                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 334                                       EXT2_BLOCK_SIZE(fs->super));
 335         if (block_size) {
 336                 if (block_size != fs->blocksize) {
 337                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 338                         goto cleanup;
 339                 }
 340         }
 341         /*
 342          * Set the blocksize to the filesystem's blocksize.
 343          */
 344         io_channel_set_blksize(fs->io, fs->blocksize);
 345
 346         /*
 347          * If this is an external journal device, don't try to read
 348          * the group descriptors, because they're not there.
 349          */
 350         if (ext2fs_has_feature_journal_dev(fs->super)) {
 351                 fs->group_desc_count = 0;
 352                 *ret_fs = fs;
 353                 return 0;
 354         }
 355
 356         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 357                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 358                 goto cleanup;
 359         }
 360         /* Precompute the FS UUID to seed other checksums */
 361         ext2fs_init_csum_seed(fs);
 362
 363         /*
 364          * Read group descriptors
 365          */
 366         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 367         if (blocks_per_group == 0 ||
 368             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 369             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 370            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 371            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 372                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 373                 goto cleanup;
 374         }
 375         groups_cnt = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 376                                        fs->super->s_first_data_block,
 377                                        blocks_per_group);
 378         if (groups_cnt >> 32) {
 379                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 380                 goto cleanup;
 381         }
 382         fs->group_desc_count =  groups_cnt;
 383         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 384             fs->super->s_inodes_count) {
 385                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 386                 goto cleanup;
 387         }
 388         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 389                                           EXT2_DESC_PER_BLOCK(fs->super));
 390         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 391                                 &fs->group_desc);
 392         if (retval)
 393                 goto cleanup;
 394         if (!group_block)
 395                 group_block = fs->super->s_first_data_block;
 396         /*
 397          * On a FS with a 1K blocksize, block 0 is reserved for bootloaders
 398          * so we must increment block numbers to any group 0 items.
 399          *
 400          * However, we cannot touch group_block directly because in the meta_bg
 401          * case, the ext2fs_descriptor_block_loc2() function will interpret
 402          * group_block != s_first_data_block to mean that we want to access the
 403          * backup group descriptors.  This is not what we want if the caller
 404          * set superblock == 0 (i.e. auto-detect the superblock), which is
 405          * what's going on here.
 406          */
 407         if (group_block == 0 && fs->blocksize == 1024)
 408                 group_zero_adjust = 1;
 409         dest = (char *) fs->group_desc;
 410 #ifdef WORDS_BIGENDIAN
 411         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 412 #endif
 413         if (ext2fs_has_feature_meta_bg(fs->super)) {
 414                 first_meta_bg = fs->super->s_first_meta_bg;
 415                 if (first_meta_bg > fs->desc_blocks)
 416                         first_meta_bg = fs->desc_blocks;
 417         } else
 418                 first_meta_bg = fs->desc_blocks;
 419         if (first_meta_bg) {
 420                 retval = io_channel_read_blk(fs->io, group_block +
 421                                              group_zero_adjust + 1,
 422                                              first_meta_bg, dest);
 423                 if (retval)
 424                         goto cleanup;
 425 #ifdef WORDS_BIGENDIAN
 426                 gdp = (struct ext2_group_desc *) dest;
 427                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 428                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 429                         ext2fs_swap_group_desc2(fs, gdp);
 430                 }
 431 #endif
 432                 dest += fs->blocksize*first_meta_bg;
 433         }
 434
 435         for (i = first_meta_bg ; i < fs->desc_blocks; i++) {
 436                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 437                 io_channel_cache_readahead(fs->io, blk, 1);
 438         }
 439
 440         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 441                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 442                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 443                 if (retval)
 444                         goto cleanup;
 445 #ifdef WORDS_BIGENDIAN
 446                 for (j=0; j < groups_per_block; j++) {
 447                         gdp = ext2fs_group_desc(fs, fs->group_desc,
 448                                                 i * groups_per_block + j);
 449                         ext2fs_swap_group_desc2(fs, gdp);
 450                 }
 451 #endif
 452                 dest += fs->blocksize;
 453         }
 454
 455         fs->stride = fs->super->s_raid_stride;
 456
 457         /*
 458          * If recovery is from backup superblock, Clear _UNININT flags &
 459          * reset bg_itable_unused to zero
 460          */
 461         if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
 462                 dgrp_t group;
 463
 464                 for (group = 0; group < fs->group_desc_count; group++) {
 465                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 466                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 467                         ext2fs_bg_itable_unused_set(fs, group, 0);
 468                         /* The checksum will be reset later, but fix it here
 469                          * anyway to avoid printing a lot of spurious errors. */
 470                         ext2fs_group_desc_csum_set(fs, group);
 471                 }
 472                 if (fs->flags & EXT2_FLAG_RW)
 473                         ext2fs_mark_super_dirty(fs);
 474         }
 475
 476         if (ext2fs_has_feature_mmp(fs->super) &&
 477             !(flags & EXT2_FLAG_SKIP_MMP) &&
 478             (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
 479                 retval = ext2fs_mmp_start(fs);
 480                 if (retval) {
 481                         fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
 482                         ext2fs_mmp_stop(fs);
 483                         goto cleanup;
 484                 }
 485         }
 486
 487         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 488         *ret_fs = fs;
 489
 490         return 0;
 491 cleanup:
 492         if (!(flags & EXT2_FLAG_NOFREE_ON_ERROR)) {
 493                 ext2fs_free(fs);
 494                 fs = NULL;
 495         }
 496         *ret_fs = fs;
 497         return retval;
 498 }
 499
 500 /*
 501  * Set/get the filesystem data I/O channel.
 502  *
 503  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 504  */
 505 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 506 {
 507         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 508                 return EXT2_ET_NOT_IMAGE_FILE;
 509         if (old_io) {
 510                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 511         }
 512         return 0;
 513 }
 514
 515 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 516 {
 517         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 518                 return EXT2_ET_NOT_IMAGE_FILE;
 519         fs->io = new_io ? new_io : fs->image_io;
 520         return 0;
 521 }
 522
 523 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 524 {
 525         errcode_t err;
 526
 527         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 528                 return EXT2_ET_NOT_IMAGE_FILE;
 529         err = io_channel_set_blksize(new_io, fs->blocksize);
 530         if (err)
 531                 return err;
 532         if ((new_io == fs->image_io) || (new_io == fs->io))
 533                 return 0;
 534         if ((fs->image_io != fs->io) &&
 535             fs->image_io)
 536                 io_channel_close(fs->image_io);
 537         if (fs->io)
 538                 io_channel_close(fs->io);
 539         fs->io = fs->image_io = new_io;
 540         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 541                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 542         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 543         return 0;
 544 }