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         char            *time_env;
 132
 133         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 134
 135         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 136         if (retval)
 137                 return retval;
 138
 139         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 140         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 141         fs->flags = flags;
 142         /* don't overwrite sb backups unless flag is explicitly cleared */
 143         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 144         fs->umask = 022;
 145
 146         time_env = getenv("E2FSPROGS_FAKE_TIME");
 147         if (time_env)
 148                 fs->now = strtoul(time_env, NULL, 0);
 149
 150         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 151         if (retval)
 152                 goto cleanup;
 153         strcpy(fs->device_name, name);
 154         cp = strchr(fs->device_name, '?');
 155         if (!io_options && cp) {
 156                 *cp++ = 0;
 157                 io_options = cp;
 158         }
 159
 160         io_flags = 0;
 161         if (flags & EXT2_FLAG_RW)
 162                 io_flags |= IO_FLAG_RW;
 163         if (flags & EXT2_FLAG_EXCLUSIVE)
 164                 io_flags |= IO_FLAG_EXCLUSIVE;
 165         if (flags & EXT2_FLAG_DIRECT_IO)
 166                 io_flags |= IO_FLAG_DIRECT_IO;
 167         retval = manager->open(fs->device_name, io_flags, &fs->io);
 168         if (retval)
 169                 goto cleanup;
 170         if (io_options &&
 171             (retval = io_channel_set_options(fs->io, io_options)))
 172                 goto cleanup;
 173         fs->image_io = fs->io;
 174         fs->io->app_data = fs;
 175         retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
 176         if (retval)
 177                 goto cleanup;
 178         if (flags & EXT2_FLAG_IMAGE_FILE) {
 179                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 180                                         &fs->image_header);
 181                 if (retval)
 182                         goto cleanup;
 183                 retval = io_channel_read_blk(fs->io, 0,
 184                                              -(int)sizeof(struct ext2_image_hdr),
 185                                              fs->image_header);
 186                 if (retval)
 187                         goto cleanup;
 188                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 189                         return EXT2_ET_MAGIC_E2IMAGE;
 190                 superblock = 1;
 191                 block_size = fs->image_header->fs_blocksize;
 192         }
 193
 194         /*
 195          * If the user specifies a specific block # for the
 196          * superblock, then he/she must also specify the block size!
 197          * Otherwise, read the master superblock located at offset
 198          * SUPERBLOCK_OFFSET from the start of the partition.
 199          *
 200          * Note: we only save a backup copy of the superblock if we
 201          * are reading the superblock from the primary superblock location.
 202          */
 203         if (superblock) {
 204                 if (!block_size) {
 205                         retval = EXT2_ET_INVALID_ARGUMENT;
 206                         goto cleanup;
 207                 }
 208                 io_channel_set_blksize(fs->io, block_size);
 209                 group_block = superblock;
 210                 fs->orig_super = 0;
 211         } else {
 212                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 213                 superblock = 1;
 214                 group_block = 0;
 215                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 216                 if (retval)
 217                         goto cleanup;
 218         }
 219         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 220                                      fs->super);
 221         if (retval)
 222                 goto cleanup;
 223         if (fs->orig_super)
 224                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 225
 226         if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
 227                 retval = 0;
 228                 if (!ext2fs_verify_csum_type(fs, fs->super))
 229                         retval = EXT2_ET_UNKNOWN_CSUM;
 230                 if (!ext2fs_superblock_csum_verify(fs, fs->super))
 231                         retval = EXT2_ET_SB_CSUM_INVALID;
 232         }
 233
 234 #ifdef WORDS_BIGENDIAN
 235         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 236         ext2fs_swap_super(fs->super);
 237 #else
 238         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 239                 retval = EXT2_ET_UNIMPLEMENTED;
 240                 goto cleanup;
 241         }
 242 #endif
 243
 244         if (fs->super->s_magic != EXT2_SUPER_MAGIC)
 245                 retval = EXT2_ET_BAD_MAGIC;
 246         if (retval)
 247                 goto cleanup;
 248
 249         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 250                 retval = EXT2_ET_REV_TOO_HIGH;
 251                 goto cleanup;
 252         }
 253
 254         /*
 255          * Check for feature set incompatibility
 256          */
 257         if (!(flags & EXT2_FLAG_FORCE)) {
 258                 features = fs->super->s_feature_incompat;
 259 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 260                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 261                         features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
 262 #endif
 263                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 264                         retval = EXT2_ET_UNSUPP_FEATURE;
 265                         goto cleanup;
 266                 }
 267
 268                 features = fs->super->s_feature_ro_compat;
 269 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 270                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 271                         features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
 272 #endif
 273                 if ((flags & EXT2_FLAG_RW) &&
 274                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 275                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 276                         goto cleanup;
 277                 }
 278
 279                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 280                     ext2fs_has_feature_journal_dev(fs->super)) {
 281                         retval = EXT2_ET_UNSUPP_FEATURE;
 282                         goto cleanup;
 283                 }
 284         }
 285
 286         if (fs->super->s_log_block_size >
 287             (unsigned) (EXT2_MAX_BLOCK_LOG_SIZE - EXT2_MIN_BLOCK_LOG_SIZE)) {
 288                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 289                 goto cleanup;
 290         }
 291
 292         /*
 293          * bigalloc requires cluster-aware bitfield operations, which at the
 294          * moment means we need EXT2_FLAG_64BITS.
 295          */
 296         if (ext2fs_has_feature_bigalloc(fs->super) &&
 297             !(flags & EXT2_FLAG_64BITS)) {
 298                 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
 299                 goto cleanup;
 300         }
 301
 302         if (!ext2fs_has_feature_bigalloc(fs->super) &&
 303             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 304                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 305                 goto cleanup;
 306         }
 307         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 308         inode_size = EXT2_INODE_SIZE(fs->super);
 309         if ((inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 310             (inode_size > fs->blocksize) ||
 311             (inode_size & (inode_size - 1))) {
 312                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 313                 goto cleanup;
 314         }
 315
 316         /* Enforce the block group descriptor size */
 317         if (ext2fs_has_feature_64bit(fs->super)) {
 318                 if (fs->super->s_desc_size < EXT2_MIN_DESC_SIZE_64BIT) {
 319                         retval = EXT2_ET_BAD_DESC_SIZE;
 320                         goto cleanup;
 321                 }
 322         } else {
 323                 if (fs->super->s_desc_size &&
 324                     fs->super->s_desc_size != EXT2_MIN_DESC_SIZE) {
 325                         retval = EXT2_ET_BAD_DESC_SIZE;
 326                         goto cleanup;
 327                 }
 328         }
 329
 330         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 331                 fs->super->s_log_block_size;
 332         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 333             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 334                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 335                 goto cleanup;
 336         }
 337         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 338                                        EXT2_INODE_SIZE(fs->super) +
 339                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 340                                       EXT2_BLOCK_SIZE(fs->super));
 341         if (block_size) {
 342                 if (block_size != fs->blocksize) {
 343                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 344                         goto cleanup;
 345                 }
 346         }
 347         /*
 348          * Set the blocksize to the filesystem's blocksize.
 349          */
 350         io_channel_set_blksize(fs->io, fs->blocksize);
 351
 352         /*
 353          * If this is an external journal device, don't try to read
 354          * the group descriptors, because they're not there.
 355          */
 356         if (ext2fs_has_feature_journal_dev(fs->super)) {
 357                 fs->group_desc_count = 0;
 358                 *ret_fs = fs;
 359                 return 0;
 360         }
 361
 362         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 363                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 364                 goto cleanup;
 365         }
 366         /* Precompute the FS UUID to seed other checksums */
 367         ext2fs_init_csum_seed(fs);
 368
 369         /*
 370          * Read group descriptors
 371          */
 372         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 373         if (blocks_per_group == 0 ||
 374             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 375             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 376            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 377            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 378                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 379                 goto cleanup;
 380         }
 381         groups_cnt = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 382                                        fs->super->s_first_data_block,
 383                                        blocks_per_group);
 384         if (groups_cnt >> 32) {
 385                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 386                 goto cleanup;
 387         }
 388         fs->group_desc_count =  groups_cnt;
 389         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 390             fs->super->s_inodes_count) {
 391                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 392                 goto cleanup;
 393         }
 394         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 395                                           EXT2_DESC_PER_BLOCK(fs->super));
 396         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 397                                 &fs->group_desc);
 398         if (retval)
 399                 goto cleanup;
 400         if (!group_block)
 401                 group_block = fs->super->s_first_data_block;
 402         /*
 403          * On a FS with a 1K blocksize, block 0 is reserved for bootloaders
 404          * so we must increment block numbers to any group 0 items.
 405          *
 406          * However, we cannot touch group_block directly because in the meta_bg
 407          * case, the ext2fs_descriptor_block_loc2() function will interpret
 408          * group_block != s_first_data_block to mean that we want to access the
 409          * backup group descriptors.  This is not what we want if the caller
 410          * set superblock == 0 (i.e. auto-detect the superblock), which is
 411          * what's going on here.
 412          */
 413         if (group_block == 0 && fs->blocksize == 1024)
 414                 group_zero_adjust = 1;
 415         dest = (char *) fs->group_desc;
 416 #ifdef WORDS_BIGENDIAN
 417         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 418 #endif
 419         if (ext2fs_has_feature_meta_bg(fs->super)) {
 420                 first_meta_bg = fs->super->s_first_meta_bg;
 421                 if (first_meta_bg > fs->desc_blocks)
 422                         first_meta_bg = fs->desc_blocks;
 423         } else
 424                 first_meta_bg = fs->desc_blocks;
 425         if (first_meta_bg) {
 426                 retval = io_channel_read_blk(fs->io, group_block +
 427                                              group_zero_adjust + 1,
 428                                              first_meta_bg, dest);
 429                 if (retval)
 430                         goto cleanup;
 431 #ifdef WORDS_BIGENDIAN
 432                 gdp = (struct ext2_group_desc *) dest;
 433                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 434                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 435                         ext2fs_swap_group_desc2(fs, gdp);
 436                 }
 437 #endif
 438                 dest += fs->blocksize*first_meta_bg;
 439         }
 440
 441         for (i = first_meta_bg ; i < fs->desc_blocks; i++) {
 442                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 443                 io_channel_cache_readahead(fs->io, blk, 1);
 444         }
 445
 446         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 447                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 448                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 449                 if (retval)
 450                         goto cleanup;
 451 #ifdef WORDS_BIGENDIAN
 452                 for (j=0; j < groups_per_block; j++) {
 453                         gdp = ext2fs_group_desc(fs, fs->group_desc,
 454                                                 i * groups_per_block + j);
 455                         ext2fs_swap_group_desc2(fs, gdp);
 456                 }
 457 #endif
 458                 dest += fs->blocksize;
 459         }
 460
 461         fs->stride = fs->super->s_raid_stride;
 462
 463         /*
 464          * If recovery is from backup superblock, Clear _UNININT flags &
 465          * reset bg_itable_unused to zero
 466          */
 467         if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
 468                 dgrp_t group;
 469
 470                 for (group = 0; group < fs->group_desc_count; group++) {
 471                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 472                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 473                         ext2fs_bg_itable_unused_set(fs, group, 0);
 474                         /* The checksum will be reset later, but fix it here
 475                          * anyway to avoid printing a lot of spurious errors. */
 476                         ext2fs_group_desc_csum_set(fs, group);
 477                 }
 478                 if (fs->flags & EXT2_FLAG_RW)
 479                         ext2fs_mark_super_dirty(fs);
 480         }
 481
 482         if (ext2fs_has_feature_mmp(fs->super) &&
 483             !(flags & EXT2_FLAG_SKIP_MMP) &&
 484             (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
 485                 retval = ext2fs_mmp_start(fs);
 486                 if (retval) {
 487                         fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
 488                         ext2fs_mmp_stop(fs);
 489                         goto cleanup;
 490                 }
 491         }
 492
 493         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 494         *ret_fs = fs;
 495
 496         return 0;
 497 cleanup:
 498         if (!(flags & EXT2_FLAG_NOFREE_ON_ERROR)) {
 499                 ext2fs_free(fs);
 500                 fs = NULL;
 501         }
 502         *ret_fs = fs;
 503         return retval;
 504 }
 505
 506 /*
 507  * Set/get the filesystem data I/O channel.
 508  *
 509  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 510  */
 511 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 512 {
 513         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 514                 return EXT2_ET_NOT_IMAGE_FILE;
 515         if (old_io) {
 516                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 517         }
 518         return 0;
 519 }
 520
 521 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 522 {
 523         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 524                 return EXT2_ET_NOT_IMAGE_FILE;
 525         fs->io = new_io ? new_io : fs->image_io;
 526         return 0;
 527 }
 528
 529 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 530 {
 531         errcode_t err;
 532
 533         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 534                 return EXT2_ET_NOT_IMAGE_FILE;
 535         err = io_channel_set_blksize(new_io, fs->blocksize);
 536         if (err)
 537                 return err;
 538         if ((new_io == fs->image_io) || (new_io == fs->io))
 539                 return 0;
 540         if ((fs->image_io != fs->io) &&
 541             fs->image_io)
 542                 io_channel_close(fs->image_io);
 543         if (fs->io)
 544                 io_channel_close(fs->io);
 545         fs->io = fs->image_io = new_io;
 546         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 547                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 548         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 549         return 0;
 550 }