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
  27 #include "ext2_fs.h"
  28
  29
  30 #include "ext2fs.h"
  31 #include "e2image.h"
  32
  33 blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs, blk64_t group_block,
  34                                      dgrp_t i)
  35 {
  36         int     bg;
  37         int     has_super = 0;
  38         blk64_t ret_blk;
  39
  40         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  41             (i < fs->super->s_first_meta_bg))
  42                 return (group_block + i + 1);
  43
  44         bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
  45         if (ext2fs_bg_has_super(fs, bg))
  46                 has_super = 1;
  47         ret_blk = ext2fs_group_first_block2(fs, bg) + has_super;
  48         /*
  49          * If group_block is not the normal value, we're trying to use
  50          * the backup group descriptors and superblock --- so use the
  51          * alternate location of the second block group in the
  52          * metablock group.  Ideally we should be testing each bg
  53          * descriptor block individually for correctness, but we don't
  54          * have the infrastructure in place to do that.
  55          */
  56         if (group_block != fs->super->s_first_data_block &&
  57             ((ret_blk + fs->super->s_blocks_per_group) <
  58              ext2fs_blocks_count(fs->super)))
  59                 ret_blk += fs->super->s_blocks_per_group;
  60         return ret_blk;
  61 }
  62
  63 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  64 {
  65         return ext2fs_descriptor_block_loc2(fs, group_block, i);
  66 }
  67
  68 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  69                       unsigned int block_size, io_manager manager,
  70                       ext2_filsys *ret_fs)
  71 {
  72         return ext2fs_open2(name, 0, flags, superblock, block_size,
  73                             manager, ret_fs);
  74 }
  75
  76 /*
  77  *  Note: if superblock is non-zero, block-size must also be non-zero.
  78  *      Superblock and block_size can be zero to use the default size.
  79  *
  80  * Valid flags for ext2fs_open()
  81  *
  82  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
  83  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
  84  *                              features aren't supported.
  85  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
  86  */
  87 errcode_t ext2fs_open2(const char *name, const char *io_options,
  88                        int flags, int superblock,
  89                        unsigned int block_size, io_manager manager,
  90                        ext2_filsys *ret_fs)
  91 {
  92         ext2_filsys     fs;
  93         errcode_t       retval;
  94         unsigned long   i, first_meta_bg;
  95         __u32           features;
  96         unsigned int    groups_per_block, blocks_per_group, io_flags;
  97         blk64_t         group_block, blk;
  98         char            *dest, *cp;
  99 #ifdef WORDS_BIGENDIAN
 100         struct ext2_group_desc *gdp;
 101         int             j;
 102 #endif
 103
 104         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 105
 106         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 107         if (retval)
 108                 return retval;
 109
 110         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 111         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 112         fs->flags = flags;
 113         /* don't overwrite sb backups unless flag is explicitly cleared */
 114         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 115         fs->umask = 022;
 116         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 117         if (retval)
 118                 goto cleanup;
 119         strcpy(fs->device_name, name);
 120         cp = strchr(fs->device_name, '?');
 121         if (!io_options && cp) {
 122                 *cp++ = 0;
 123                 io_options = cp;
 124         }
 125
 126         io_flags = 0;
 127         if (flags & EXT2_FLAG_RW)
 128                 io_flags |= IO_FLAG_RW;
 129         if (flags & EXT2_FLAG_EXCLUSIVE)
 130                 io_flags |= IO_FLAG_EXCLUSIVE;
 131         if (flags & EXT2_FLAG_DIRECT_IO)
 132                 io_flags |= IO_FLAG_DIRECT_IO;
 133         retval = manager->open(fs->device_name, io_flags, &fs->io);
 134         if (retval)
 135                 goto cleanup;
 136         if (io_options &&
 137             (retval = io_channel_set_options(fs->io, io_options)))
 138                 goto cleanup;
 139         fs->image_io = fs->io;
 140         fs->io->app_data = fs;
 141         retval = ext2fs_get_memalign(SUPERBLOCK_SIZE, 512, &fs->super);
 142         if (retval)
 143                 goto cleanup;
 144         if (flags & EXT2_FLAG_IMAGE_FILE) {
 145                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 146                                         &fs->image_header);
 147                 if (retval)
 148                         goto cleanup;
 149                 retval = io_channel_read_blk(fs->io, 0,
 150                                              -(int)sizeof(struct ext2_image_hdr),
 151                                              fs->image_header);
 152                 if (retval)
 153                         goto cleanup;
 154                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 155                         return EXT2_ET_MAGIC_E2IMAGE;
 156                 superblock = 1;
 157                 block_size = fs->image_header->fs_blocksize;
 158         }
 159
 160         /*
 161          * If the user specifies a specific block # for the
 162          * superblock, then he/she must also specify the block size!
 163          * Otherwise, read the master superblock located at offset
 164          * SUPERBLOCK_OFFSET from the start of the partition.
 165          *
 166          * Note: we only save a backup copy of the superblock if we
 167          * are reading the superblock from the primary superblock location.
 168          */
 169         if (superblock) {
 170                 if (!block_size) {
 171                         retval = EXT2_ET_INVALID_ARGUMENT;
 172                         goto cleanup;
 173                 }
 174                 io_channel_set_blksize(fs->io, block_size);
 175                 group_block = superblock;
 176                 fs->orig_super = 0;
 177         } else {
 178                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 179                 superblock = 1;
 180                 group_block = 0;
 181                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 182                 if (retval)
 183                         goto cleanup;
 184         }
 185         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 186                                      fs->super);
 187         if (retval)
 188                 goto cleanup;
 189         if (fs->orig_super)
 190                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 191
 192 #ifdef WORDS_BIGENDIAN
 193         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 194         ext2fs_swap_super(fs->super);
 195 #else
 196         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 197                 retval = EXT2_ET_UNIMPLEMENTED;
 198                 goto cleanup;
 199         }
 200 #endif
 201
 202         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 203                 retval = EXT2_ET_BAD_MAGIC;
 204                 goto cleanup;
 205         }
 206         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 207                 retval = EXT2_ET_REV_TOO_HIGH;
 208                 goto cleanup;
 209         }
 210
 211         /*
 212          * Check for feature set incompatibility
 213          */
 214         if (!(flags & EXT2_FLAG_FORCE)) {
 215                 features = fs->super->s_feature_incompat;
 216 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 217                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 218                         features &= ~EXT2_LIB_SOFTSUPP_INCOMPAT;
 219 #endif
 220                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 221                         retval = EXT2_ET_UNSUPP_FEATURE;
 222                         goto cleanup;
 223                 }
 224
 225                 features = fs->super->s_feature_ro_compat;
 226 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 227                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 228                         features &= ~EXT2_LIB_SOFTSUPP_RO_COMPAT;
 229 #endif
 230                 if ((flags & EXT2_FLAG_RW) &&
 231                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 232                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 233                         goto cleanup;
 234                 }
 235
 236                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 237                     (fs->super->s_feature_incompat &
 238                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 239                         retval = EXT2_ET_UNSUPP_FEATURE;
 240                         goto cleanup;
 241                 }
 242         }
 243
 244         if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
 245             EXT2_MAX_BLOCK_LOG_SIZE) {
 246                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 247                 goto cleanup;
 248         }
 249         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 250                                         EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
 251             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 252                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 253                 goto cleanup;
 254         }
 255         fs->fragsize = fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 256         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 257                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 258                 goto cleanup;
 259         }
 260         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 261                 fs->super->s_log_block_size;
 262         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 263             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 264                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 265                 goto cleanup;
 266         }
 267         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 268                                        EXT2_INODE_SIZE(fs->super) +
 269                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 270                                       EXT2_BLOCK_SIZE(fs->super));
 271         if (block_size) {
 272                 if (block_size != fs->blocksize) {
 273                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 274                         goto cleanup;
 275                 }
 276         }
 277         /*
 278          * Set the blocksize to the filesystem's blocksize.
 279          */
 280         io_channel_set_blksize(fs->io, fs->blocksize);
 281
 282         /*
 283          * If this is an external journal device, don't try to read
 284          * the group descriptors, because they're not there.
 285          */
 286         if (fs->super->s_feature_incompat &
 287             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 288                 fs->group_desc_count = 0;
 289                 *ret_fs = fs;
 290                 return 0;
 291         }
 292
 293         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 294                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 295                 goto cleanup;
 296         }
 297
 298         /*
 299          * Read group descriptors
 300          */
 301         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 302         if (blocks_per_group == 0 ||
 303             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 304             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 305            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 306            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 307                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 308                 goto cleanup;
 309         }
 310         fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 311                                                  fs->super->s_first_data_block,
 312                                                  blocks_per_group);
 313         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 314             fs->super->s_inodes_count) {
 315                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 316                 goto cleanup;
 317         }
 318         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 319                                           EXT2_DESC_PER_BLOCK(fs->super));
 320         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 321                                 &fs->group_desc);
 322         if (retval)
 323                 goto cleanup;
 324         if (!group_block)
 325                 group_block = fs->super->s_first_data_block;
 326         if (group_block == 0 && fs->blocksize == 1024)
 327                 group_block = 1; /* Deal with 1024 blocksize && bigalloc */
 328         dest = (char *) fs->group_desc;
 329         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 330         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 331                 first_meta_bg = fs->super->s_first_meta_bg;
 332         else
 333                 first_meta_bg = fs->desc_blocks;
 334         if (first_meta_bg) {
 335                 retval = io_channel_read_blk(fs->io, group_block+1,
 336                                              first_meta_bg, dest);
 337                 if (retval)
 338                         goto cleanup;
 339 #ifdef WORDS_BIGENDIAN
 340                 gdp = (struct ext2_group_desc *) dest;
 341                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 342                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 343                         ext2fs_swap_group_desc2(fs, gdp);
 344                 }
 345 #endif
 346                 dest += fs->blocksize*first_meta_bg;
 347         }
 348         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 349                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 350                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 351                 if (retval)
 352                         goto cleanup;
 353 #ifdef WORDS_BIGENDIAN
 354                 for (j=0; j < groups_per_block; j++) {
 355                         /* The below happens to work... be careful. */
 356                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 357                         ext2fs_swap_group_desc2(fs, gdp);
 358                 }
 359 #endif
 360                 dest += fs->blocksize;
 361         }
 362
 363         fs->stride = fs->super->s_raid_stride;
 364
 365         /*
 366          * If recovery is from backup superblock, Clear _UNININT flags &
 367          * reset bg_itable_unused to zero
 368          */
 369         if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 370                                         EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
 371                 dgrp_t group;
 372
 373                 for (group = 0; group < fs->group_desc_count; group++) {
 374                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 375                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 376                         ext2fs_bg_itable_unused_set(fs, group, 0);
 377                 }
 378                 ext2fs_mark_super_dirty(fs);
 379         }
 380
 381         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 382         *ret_fs = fs;
 383         return 0;
 384 cleanup:
 385         if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
 386                 *ret_fs = fs;
 387         else
 388                 ext2fs_free(fs);
 389         return retval;
 390 }
 391
 392 /*
 393  * Set/get the filesystem data I/O channel.
 394  *
 395  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 396  */
 397 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 398 {
 399         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 400                 return EXT2_ET_NOT_IMAGE_FILE;
 401         if (old_io) {
 402                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 403         }
 404         return 0;
 405 }
 406
 407 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 408 {
 409         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 410                 return EXT2_ET_NOT_IMAGE_FILE;
 411         fs->io = new_io ? new_io : fs->image_io;
 412         return 0;
 413 }
 414
 415 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 416 {
 417         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 418                 return EXT2_ET_NOT_IMAGE_FILE;
 419         fs->io = fs->image_io = new_io;
 420         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 421                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 422         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 423         return 0;
 424 }