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 (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  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                     (fs->super->s_feature_incompat &
 273                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 274                         retval = EXT2_ET_UNSUPP_FEATURE;
 275                         goto cleanup;
 276                 }
 277         }
 278
 279         if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
 280             EXT2_MAX_BLOCK_LOG_SIZE) {
 281                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 282                 goto cleanup;
 283         }
 284
 285         /*
 286          * bigalloc requires cluster-aware bitfield operations, which at the
 287          * moment means we need EXT2_FLAG_64BITS.
 288          */
 289         if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 290                                        EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
 291             !(flags & EXT2_FLAG_64BITS)) {
 292                 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
 293                 goto cleanup;
 294         }
 295
 296         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 297                                         EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
 298             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 299                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 300                 goto cleanup;
 301         }
 302         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 303         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 304                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 305                 goto cleanup;
 306         }
 307
 308         /* Enforce the block group descriptor size */
 309         if (fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_64BIT) {
 310                 if (fs->super->s_desc_size < EXT2_MIN_DESC_SIZE_64BIT) {
 311                         retval = EXT2_ET_BAD_DESC_SIZE;
 312                         goto cleanup;
 313                 }
 314         } else {
 315                 if (fs->super->s_desc_size &&
 316                     fs->super->s_desc_size != EXT2_MIN_DESC_SIZE) {
 317                         retval = EXT2_ET_BAD_DESC_SIZE;
 318                         goto cleanup;
 319                 }
 320         }
 321
 322         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 323                 fs->super->s_log_block_size;
 324         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 325             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 326                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 327                 goto cleanup;
 328         }
 329         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 330                                        EXT2_INODE_SIZE(fs->super) +
 331                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 332                                       EXT2_BLOCK_SIZE(fs->super));
 333         if (block_size) {
 334                 if (block_size != fs->blocksize) {
 335                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 336                         goto cleanup;
 337                 }
 338         }
 339         /*
 340          * Set the blocksize to the filesystem's blocksize.
 341          */
 342         io_channel_set_blksize(fs->io, fs->blocksize);
 343
 344         /*
 345          * If this is an external journal device, don't try to read
 346          * the group descriptors, because they're not there.
 347          */
 348         if (fs->super->s_feature_incompat &
 349             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 350                 fs->group_desc_count = 0;
 351                 *ret_fs = fs;
 352                 return 0;
 353         }
 354
 355         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 356                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 357                 goto cleanup;
 358         }
 359         /* Precompute the FS UUID to seed other checksums */
 360         ext2fs_init_csum_seed(fs);
 361
 362         /*
 363          * Read group descriptors
 364          */
 365         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 366         if (blocks_per_group == 0 ||
 367             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 368             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 369            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 370            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 371                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 372                 goto cleanup;
 373         }
 374         fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 375                                                  fs->super->s_first_data_block,
 376                                                  blocks_per_group);
 377         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 378             fs->super->s_inodes_count) {
 379                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 380                 goto cleanup;
 381         }
 382         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 383                                           EXT2_DESC_PER_BLOCK(fs->super));
 384         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 385                                 &fs->group_desc);
 386         if (retval)
 387                 goto cleanup;
 388         if (!group_block)
 389                 group_block = fs->super->s_first_data_block;
 390         /*
 391          * On a FS with a 1K blocksize, block 0 is reserved for bootloaders
 392          * so we must increment block numbers to any group 0 items.
 393          *
 394          * However, we cannot touch group_block directly because in the meta_bg
 395          * case, the ext2fs_descriptor_block_loc2() function will interpret
 396          * group_block != s_first_data_block to mean that we want to access the
 397          * backup group descriptors.  This is not what we want if the caller
 398          * set superblock == 0 (i.e. auto-detect the superblock), which is
 399          * what's going on here.
 400          */
 401         if (group_block == 0 && fs->blocksize == 1024)
 402                 group_zero_adjust = 1;
 403         dest = (char *) fs->group_desc;
 404 #ifdef WORDS_BIGENDIAN
 405         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 406 #endif
 407         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) {
 408                 first_meta_bg = fs->super->s_first_meta_bg;
 409                 if (first_meta_bg > fs->desc_blocks)
 410                         first_meta_bg = fs->desc_blocks;
 411         } else
 412                 first_meta_bg = fs->desc_blocks;
 413         if (first_meta_bg) {
 414                 retval = io_channel_read_blk(fs->io, group_block +
 415                                              group_zero_adjust + 1,
 416                                              first_meta_bg, dest);
 417                 if (retval)
 418                         goto cleanup;
 419 #ifdef WORDS_BIGENDIAN
 420                 gdp = (struct ext2_group_desc *) dest;
 421                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 422                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 423                         ext2fs_swap_group_desc2(fs, gdp);
 424                 }
 425 #endif
 426                 dest += fs->blocksize*first_meta_bg;
 427         }
 428         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 429                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 430                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 431                 if (retval)
 432                         goto cleanup;
 433 #ifdef WORDS_BIGENDIAN
 434                 for (j=0; j < groups_per_block; j++) {
 435                         gdp = ext2fs_group_desc(fs, fs->group_desc,
 436                                                 i * groups_per_block + j);
 437                         ext2fs_swap_group_desc2(fs, gdp);
 438                 }
 439 #endif
 440                 dest += fs->blocksize;
 441         }
 442
 443         fs->stride = fs->super->s_raid_stride;
 444
 445         /*
 446          * If recovery is from backup superblock, Clear _UNININT flags &
 447          * reset bg_itable_unused to zero
 448          */
 449         if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
 450                 dgrp_t group;
 451
 452                 for (group = 0; group < fs->group_desc_count; group++) {
 453                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 454                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 455                         ext2fs_bg_itable_unused_set(fs, group, 0);
 456                         /* The checksum will be reset later, but fix it here
 457                          * anyway to avoid printing a lot of spurious errors. */
 458                         ext2fs_group_desc_csum_set(fs, group);
 459                 }
 460                 if (fs->flags & EXT2_FLAG_RW)
 461                         ext2fs_mark_super_dirty(fs);
 462         }
 463
 464         if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) &&
 465             !(flags & EXT2_FLAG_SKIP_MMP) &&
 466             (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
 467                 retval = ext2fs_mmp_start(fs);
 468                 if (retval) {
 469                         fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
 470                         ext2fs_mmp_stop(fs);
 471                         goto cleanup;
 472                 }
 473         }
 474
 475         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 476         *ret_fs = fs;
 477
 478         return 0;
 479 cleanup:
 480         if (!(flags & EXT2_FLAG_NOFREE_ON_ERROR)) {
 481                 ext2fs_free(fs);
 482                 fs = NULL;
 483         }
 484         *ret_fs = fs;
 485         return retval;
 486 }
 487
 488 /*
 489  * Set/get the filesystem data I/O channel.
 490  *
 491  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 492  */
 493 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 494 {
 495         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 496                 return EXT2_ET_NOT_IMAGE_FILE;
 497         if (old_io) {
 498                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 499         }
 500         return 0;
 501 }
 502
 503 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 504 {
 505         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 506                 return EXT2_ET_NOT_IMAGE_FILE;
 507         fs->io = new_io ? new_io : fs->image_io;
 508         return 0;
 509 }
 510
 511 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 512 {
 513         errcode_t err;
 514
 515         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 516                 return EXT2_ET_NOT_IMAGE_FILE;
 517         err = io_channel_set_blksize(new_io, fs->blocksize);
 518         if (err)
 519                 return err;
 520         if ((new_io == fs->image_io) || (new_io == fs->io))
 521                 return 0;
 522         if ((fs->image_io != fs->io) &&
 523             fs->image_io)
 524                 io_channel_close(fs->image_io);
 525         if (fs->io)
 526                 io_channel_close(fs->io);
 527         fs->io = fs->image_io = new_io;
 528         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 529                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 530         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 531         return 0;
 532 }