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;
  41         blk64_t ret_blk;
  42
  43         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  44             (i < fs->super->s_first_meta_bg))
  45                 return (group_block + i + 1);
  46
  47         bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
  48         if (ext2fs_bg_has_super(fs, bg))
  49                 has_super = 1;
  50         ret_blk = ext2fs_group_first_block2(fs, bg) + has_super;
  51         /*
  52          * If group_block is not the normal value, we're trying to use
  53          * the backup group descriptors and superblock --- so use the
  54          * alternate location of the second block group in the
  55          * metablock group.  Ideally we should be testing each bg
  56          * descriptor block individually for correctness, but we don't
  57          * have the infrastructure in place to do that.
  58          */
  59         if (group_block != fs->super->s_first_data_block &&
  60             ((ret_blk + fs->super->s_blocks_per_group) <
  61              ext2fs_blocks_count(fs->super)))
  62                 ret_blk += fs->super->s_blocks_per_group;
  63         return ret_blk;
  64 }
  65
  66 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  67 {
  68         return ext2fs_descriptor_block_loc2(fs, group_block, i);
  69 }
  70
  71 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  72                       unsigned int block_size, io_manager manager,
  73                       ext2_filsys *ret_fs)
  74 {
  75         return ext2fs_open2(name, 0, flags, superblock, block_size,
  76                             manager, ret_fs);
  77 }
  78
  79 /*
  80  *  Note: if superblock is non-zero, block-size must also be non-zero.
  81  *      Superblock and block_size can be zero to use the default size.
  82  *
  83  * Valid flags for ext2fs_open()
  84  *
  85  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
  86  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
  87  *                              features aren't supported.
  88  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
  89  *      EXT2_FLAG_SKIP_MMP - Open without multi-mount protection check.
  90  *      EXT2_FLAG_64BITS - Allow 64-bit bitfields (needed for large
  91  *                              filesystems)
  92  */
  93 errcode_t ext2fs_open2(const char *name, const char *io_options,
  94                        int flags, int superblock,
  95                        unsigned int block_size, io_manager manager,
  96                        ext2_filsys *ret_fs)
  97 {
  98         ext2_filsys     fs;
  99         errcode_t       retval;
 100         unsigned long   i, first_meta_bg;
 101         __u32           features;
 102         unsigned int    blocks_per_group, io_flags;
 103         blk64_t         group_block, blk;
 104         char            *dest, *cp;
 105 #ifdef WORDS_BIGENDIAN
 106         unsigned int    groups_per_block;
 107         struct ext2_group_desc *gdp;
 108         int             j;
 109 #endif
 110
 111         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 112
 113         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 114         if (retval)
 115                 return retval;
 116
 117         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 118         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 119         fs->flags = flags;
 120         /* don't overwrite sb backups unless flag is explicitly cleared */
 121         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 122         fs->umask = 022;
 123         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 124         if (retval)
 125                 goto cleanup;
 126         strcpy(fs->device_name, name);
 127         cp = strchr(fs->device_name, '?');
 128         if (!io_options && cp) {
 129                 *cp++ = 0;
 130                 io_options = cp;
 131         }
 132
 133         io_flags = 0;
 134         if (flags & EXT2_FLAG_RW)
 135                 io_flags |= IO_FLAG_RW;
 136         if (flags & EXT2_FLAG_EXCLUSIVE)
 137                 io_flags |= IO_FLAG_EXCLUSIVE;
 138         if (flags & EXT2_FLAG_DIRECT_IO)
 139                 io_flags |= IO_FLAG_DIRECT_IO;
 140         retval = manager->open(fs->device_name, io_flags, &fs->io);
 141         if (retval)
 142                 goto cleanup;
 143         if (io_options &&
 144             (retval = io_channel_set_options(fs->io, io_options)))
 145                 goto cleanup;
 146         fs->image_io = fs->io;
 147         fs->io->app_data = fs;
 148         retval = io_channel_alloc_buf(fs->io, -SUPERBLOCK_SIZE, &fs->super);
 149         if (retval)
 150                 goto cleanup;
 151         if (flags & EXT2_FLAG_IMAGE_FILE) {
 152                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 153                                         &fs->image_header);
 154                 if (retval)
 155                         goto cleanup;
 156                 retval = io_channel_read_blk(fs->io, 0,
 157                                              -(int)sizeof(struct ext2_image_hdr),
 158                                              fs->image_header);
 159                 if (retval)
 160                         goto cleanup;
 161                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 162                         return EXT2_ET_MAGIC_E2IMAGE;
 163                 superblock = 1;
 164                 block_size = fs->image_header->fs_blocksize;
 165         }
 166
 167         /*
 168          * If the user specifies a specific block # for the
 169          * superblock, then he/she must also specify the block size!
 170          * Otherwise, read the master superblock located at offset
 171          * SUPERBLOCK_OFFSET from the start of the partition.
 172          *
 173          * Note: we only save a backup copy of the superblock if we
 174          * are reading the superblock from the primary superblock location.
 175          */
 176         if (superblock) {
 177                 if (!block_size) {
 178                         retval = EXT2_ET_INVALID_ARGUMENT;
 179                         goto cleanup;
 180                 }
 181                 io_channel_set_blksize(fs->io, block_size);
 182                 group_block = superblock;
 183                 fs->orig_super = 0;
 184         } else {
 185                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 186                 superblock = 1;
 187                 group_block = 0;
 188                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 189                 if (retval)
 190                         goto cleanup;
 191         }
 192         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 193                                      fs->super);
 194         if (retval)
 195                 goto cleanup;
 196         if (fs->orig_super)
 197                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 198
 199         if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)) {
 200                 retval = 0;
 201                 if (!ext2fs_verify_csum_type(fs, fs->super))
 202                         retval = EXT2_ET_UNKNOWN_CSUM;
 203                 if (!ext2fs_superblock_csum_verify(fs, fs->super))
 204                         retval = EXT2_ET_SB_CSUM_INVALID;
 205                 if (retval)
 206                         goto cleanup;
 207         }
 208
 209 #ifdef WORDS_BIGENDIAN
 210         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 211         ext2fs_swap_super(fs->super);
 212 #else
 213         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 214                 retval = EXT2_ET_UNIMPLEMENTED;
 215                 goto cleanup;
 216         }
 217 #endif
 218
 219         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 220                 retval = EXT2_ET_BAD_MAGIC;
 221                 goto cleanup;
 222         }
 223         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 224                 retval = EXT2_ET_REV_TOO_HIGH;
 225                 goto cleanup;
 226         }
 227
 228         /*
 229          * Check for feature set incompatibility
 230          */
 231         if (!(flags & EXT2_FLAG_FORCE)) {
 232                 features = fs->super->s_feature_incompat;
 233 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 234                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 235                         features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
 236 #endif
 237                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 238                         retval = EXT2_ET_UNSUPP_FEATURE;
 239                         goto cleanup;
 240                 }
 241
 242                 features = fs->super->s_feature_ro_compat;
 243 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 244                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 245                         features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
 246 #endif
 247                 if ((flags & EXT2_FLAG_RW) &&
 248                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 249                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 250                         goto cleanup;
 251                 }
 252
 253                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 254                     (fs->super->s_feature_incompat &
 255                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 256                         retval = EXT2_ET_UNSUPP_FEATURE;
 257                         goto cleanup;
 258                 }
 259         }
 260
 261         if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
 262             EXT2_MAX_BLOCK_LOG_SIZE) {
 263                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 264                 goto cleanup;
 265         }
 266
 267         /*
 268          * bigalloc requires cluster-aware bitfield operations, which at the
 269          * moment means we need EXT2_FLAG_64BITS.
 270          */
 271         if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 272                                        EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
 273             !(flags & EXT2_FLAG_64BITS)) {
 274                 retval = EXT2_ET_CANT_USE_LEGACY_BITMAPS;
 275                 goto cleanup;
 276         }
 277
 278         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 279                                         EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
 280             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 281                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 282                 goto cleanup;
 283         }
 284         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 285         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 286                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 287                 goto cleanup;
 288         }
 289
 290         /* Enforce the block group descriptor size */
 291         if (fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_64BIT) {
 292                 if (fs->super->s_desc_size < EXT2_MIN_DESC_SIZE_64BIT) {
 293                         retval = EXT2_ET_BAD_DESC_SIZE;
 294                         goto cleanup;
 295                 }
 296         } else {
 297                 if (fs->super->s_desc_size &&
 298                     fs->super->s_desc_size != EXT2_MIN_DESC_SIZE) {
 299                         retval = EXT2_ET_BAD_DESC_SIZE;
 300                         goto cleanup;
 301                 }
 302         }
 303
 304         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 305                 fs->super->s_log_block_size;
 306         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 307             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 308                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 309                 goto cleanup;
 310         }
 311         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 312                                        EXT2_INODE_SIZE(fs->super) +
 313                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 314                                       EXT2_BLOCK_SIZE(fs->super));
 315         if (block_size) {
 316                 if (block_size != fs->blocksize) {
 317                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 318                         goto cleanup;
 319                 }
 320         }
 321         /*
 322          * Set the blocksize to the filesystem's blocksize.
 323          */
 324         io_channel_set_blksize(fs->io, fs->blocksize);
 325
 326         /*
 327          * If this is an external journal device, don't try to read
 328          * the group descriptors, because they're not there.
 329          */
 330         if (fs->super->s_feature_incompat &
 331             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 332                 fs->group_desc_count = 0;
 333                 *ret_fs = fs;
 334                 return 0;
 335         }
 336
 337         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 338                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 339                 goto cleanup;
 340         }
 341         /* Precompute the FS UUID to seed other checksums */
 342         ext2fs_init_csum_seed(fs);
 343
 344         /*
 345          * Read group descriptors
 346          */
 347         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 348         if (blocks_per_group == 0 ||
 349             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 350             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 351            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 352            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 353                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 354                 goto cleanup;
 355         }
 356         fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 357                                                  fs->super->s_first_data_block,
 358                                                  blocks_per_group);
 359         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 360             fs->super->s_inodes_count) {
 361                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 362                 goto cleanup;
 363         }
 364         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 365                                           EXT2_DESC_PER_BLOCK(fs->super));
 366         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 367                                 &fs->group_desc);
 368         if (retval)
 369                 goto cleanup;
 370         if (!group_block)
 371                 group_block = fs->super->s_first_data_block;
 372         if (group_block == 0 && fs->blocksize == 1024)
 373                 group_block = 1; /* Deal with 1024 blocksize && bigalloc */
 374         dest = (char *) fs->group_desc;
 375 #ifdef WORDS_BIGENDIAN
 376         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 377 #endif
 378         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 379                 first_meta_bg = fs->super->s_first_meta_bg;
 380         else
 381                 first_meta_bg = fs->desc_blocks;
 382         if (first_meta_bg) {
 383                 retval = io_channel_read_blk(fs->io, group_block+1,
 384                                              first_meta_bg, dest);
 385                 if (retval)
 386                         goto cleanup;
 387 #ifdef WORDS_BIGENDIAN
 388                 gdp = (struct ext2_group_desc *) dest;
 389                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 390                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 391                         ext2fs_swap_group_desc2(fs, gdp);
 392                 }
 393 #endif
 394                 dest += fs->blocksize*first_meta_bg;
 395         }
 396         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 397                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 398                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 399                 if (retval)
 400                         goto cleanup;
 401 #ifdef WORDS_BIGENDIAN
 402                 for (j=0; j < groups_per_block; j++) {
 403                         gdp = ext2fs_group_desc(fs, fs->group_desc,
 404                                                 i * groups_per_block + j);
 405                         ext2fs_swap_group_desc2(fs, gdp);
 406                 }
 407 #endif
 408                 dest += fs->blocksize;
 409         }
 410
 411         fs->stride = fs->super->s_raid_stride;
 412
 413         /*
 414          * If recovery is from backup superblock, Clear _UNININT flags &
 415          * reset bg_itable_unused to zero
 416          */
 417         if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
 418                 dgrp_t group;
 419
 420                 for (group = 0; group < fs->group_desc_count; group++) {
 421                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 422                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 423                         ext2fs_bg_itable_unused_set(fs, group, 0);
 424                         /* The checksum will be reset later, but fix it here
 425                          * anyway to avoid printing a lot of spurious errors. */
 426                         ext2fs_group_desc_csum_set(fs, group);
 427                 }
 428                 if (fs->flags & EXT2_FLAG_RW)
 429                         ext2fs_mark_super_dirty(fs);
 430         }
 431
 432         if ((fs->super->s_feature_incompat & EXT4_FEATURE_INCOMPAT_MMP) &&
 433             !(flags & EXT2_FLAG_SKIP_MMP) &&
 434             (flags & (EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE))) {
 435                 retval = ext2fs_mmp_start(fs);
 436                 if (retval) {
 437                         fs->flags |= EXT2_FLAG_SKIP_MMP; /* just do cleanup */
 438                         ext2fs_mmp_stop(fs);
 439                         goto cleanup;
 440                 }
 441         }
 442
 443         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 444         *ret_fs = fs;
 445
 446         return 0;
 447 cleanup:
 448         if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
 449                 *ret_fs = fs;
 450         else
 451                 ext2fs_free(fs);
 452         return retval;
 453 }
 454
 455 /*
 456  * Set/get the filesystem data I/O channel.
 457  *
 458  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 459  */
 460 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 461 {
 462         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 463                 return EXT2_ET_NOT_IMAGE_FILE;
 464         if (old_io) {
 465                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 466         }
 467         return 0;
 468 }
 469
 470 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 471 {
 472         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 473                 return EXT2_ET_NOT_IMAGE_FILE;
 474         fs->io = new_io ? new_io : fs->image_io;
 475         return 0;
 476 }
 477
 478 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 479 {
 480         errcode_t err;
 481
 482         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 483                 return EXT2_ET_NOT_IMAGE_FILE;
 484         err = io_channel_set_blksize(new_io, fs->blocksize);
 485         if (err)
 486                 return err;
 487         if ((new_io == fs->image_io) || (new_io == fs->io))
 488                 return 0;
 489         if ((fs->image_io != fs->io) &&
 490             fs->image_io)
 491                 io_channel_close(fs->image_io);
 492         if (fs->io)
 493                 io_channel_close(fs->io);
 494         fs->io = fs->image_io = new_io;
 495         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 496                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 497         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 498         return 0;
 499 }