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 <stdio.h>
  13 #include <string.h>
  14 #if HAVE_UNISTD_H
  15 #include <unistd.h>
  16 #endif
  17 #include <fcntl.h>
  18 #include <time.h>
  19 #if HAVE_SYS_STAT_H
  20 #include <sys/stat.h>
  21 #endif
  22 #if HAVE_SYS_TYPES_H
  23 #include <sys/types.h>
  24 #endif
  25
  26 #include "ext2_fs.h"
  27
  28
  29 #include "ext2fs.h"
  30 #include "e2image.h"
  31
  32 blk64_t ext2fs_descriptor_block_loc2(ext2_filsys fs, blk64_t group_block,
  33                                      dgrp_t i)
  34 {
  35         int     bg;
  36         int     has_super = 0;
  37         blk64_t ret_blk;
  38
  39         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  40             (i < fs->super->s_first_meta_bg))
  41                 return (group_block + i + 1);
  42
  43         bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
  44         if (ext2fs_bg_has_super(fs, bg))
  45                 has_super = 1;
  46         ret_blk = ext2fs_group_first_block2(fs, bg) + has_super;
  47         /*
  48          * If group_block is not the normal value, we're trying to use
  49          * the backup group descriptors and superblock --- so use the
  50          * alternate location of the second block group in the
  51          * metablock group.  Ideally we should be testing each bg
  52          * descriptor block individually for correctness, but we don't
  53          * have the infrastructure in place to do that.
  54          */
  55         if (group_block != fs->super->s_first_data_block &&
  56             ((ret_blk + fs->super->s_blocks_per_group) <
  57              ext2fs_blocks_count(fs->super)))
  58                 ret_blk += fs->super->s_blocks_per_group;
  59         return ret_blk;
  60 }
  61
  62 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  63 {
  64         return ext2fs_descriptor_block_loc2(fs, group_block, i);
  65 }
  66
  67 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  68                       unsigned int block_size, io_manager manager,
  69                       ext2_filsys *ret_fs)
  70 {
  71         return ext2fs_open2(name, 0, flags, superblock, block_size,
  72                             manager, ret_fs);
  73 }
  74
  75 /*
  76  *  Note: if superblock is non-zero, block-size must also be non-zero.
  77  *      Superblock and block_size can be zero to use the default size.
  78  *
  79  * Valid flags for ext2fs_open()
  80  *
  81  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
  82  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
  83  *                              features aren't supported.
  84  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
  85  */
  86 errcode_t ext2fs_open2(const char *name, const char *io_options,
  87                        int flags, int superblock,
  88                        unsigned int block_size, io_manager manager,
  89                        ext2_filsys *ret_fs)
  90 {
  91         ext2_filsys     fs;
  92         errcode_t       retval;
  93         unsigned long   i, first_meta_bg;
  94         __u32           features;
  95         int             groups_per_block, blocks_per_group, io_flags;
  96         blk64_t         group_block, blk;
  97         char            *dest, *cp;
  98 #ifdef WORDS_BIGENDIAN
  99         struct ext2_group_desc *gdp;
 100         int             j;
 101 #endif
 102
 103         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 104
 105         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 106         if (retval)
 107                 return retval;
 108
 109         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 110         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 111         fs->flags = flags;
 112         /* don't overwrite sb backups unless flag is explicitly cleared */
 113         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 114         fs->umask = 022;
 115         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 116         if (retval)
 117                 goto cleanup;
 118         strcpy(fs->device_name, name);
 119         cp = strchr(fs->device_name, '?');
 120         if (!io_options && cp) {
 121                 *cp++ = 0;
 122                 io_options = cp;
 123         }
 124
 125         io_flags = 0;
 126         if (flags & EXT2_FLAG_RW)
 127                 io_flags |= IO_FLAG_RW;
 128         if (flags & EXT2_FLAG_EXCLUSIVE)
 129                 io_flags |= IO_FLAG_EXCLUSIVE;
 130         if (flags & EXT2_FLAG_DIRECT_IO)
 131                 io_flags |= IO_FLAG_DIRECT_IO;
 132         retval = manager->open(fs->device_name, io_flags, &fs->io);
 133         if (retval)
 134                 goto cleanup;
 135         if (io_options &&
 136             (retval = io_channel_set_options(fs->io, io_options)))
 137                 goto cleanup;
 138         fs->image_io = fs->io;
 139         fs->io->app_data = fs;
 140         retval = ext2fs_get_memalign(SUPERBLOCK_SIZE, 512, &fs->super);
 141         if (retval)
 142                 goto cleanup;
 143         if (flags & EXT2_FLAG_IMAGE_FILE) {
 144                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 145                                         &fs->image_header);
 146                 if (retval)
 147                         goto cleanup;
 148                 retval = io_channel_read_blk(fs->io, 0,
 149                                              -(int)sizeof(struct ext2_image_hdr),
 150                                              fs->image_header);
 151                 if (retval)
 152                         goto cleanup;
 153                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 154                         return EXT2_ET_MAGIC_E2IMAGE;
 155                 superblock = 1;
 156                 block_size = fs->image_header->fs_blocksize;
 157         }
 158
 159         /*
 160          * If the user specifies a specific block # for the
 161          * superblock, then he/she must also specify the block size!
 162          * Otherwise, read the master superblock located at offset
 163          * SUPERBLOCK_OFFSET from the start of the partition.
 164          *
 165          * Note: we only save a backup copy of the superblock if we
 166          * are reading the superblock from the primary superblock location.
 167          */
 168         if (superblock) {
 169                 if (!block_size) {
 170                         retval = EXT2_ET_INVALID_ARGUMENT;
 171                         goto cleanup;
 172                 }
 173                 io_channel_set_blksize(fs->io, block_size);
 174                 group_block = superblock;
 175                 fs->orig_super = 0;
 176         } else {
 177                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 178                 superblock = 1;
 179                 group_block = 0;
 180                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 181                 if (retval)
 182                         goto cleanup;
 183         }
 184         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 185                                      fs->super);
 186         if (retval)
 187                 goto cleanup;
 188         if (fs->orig_super)
 189                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 190
 191 #ifdef WORDS_BIGENDIAN
 192         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 193         ext2fs_swap_super(fs->super);
 194 #else
 195         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 196                 retval = EXT2_ET_UNIMPLEMENTED;
 197                 goto cleanup;
 198         }
 199 #endif
 200
 201         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 202                 retval = EXT2_ET_BAD_MAGIC;
 203                 goto cleanup;
 204         }
 205         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 206                 retval = EXT2_ET_REV_TOO_HIGH;
 207                 goto cleanup;
 208         }
 209
 210         /*
 211          * Check for feature set incompatibility
 212          */
 213         if (!(flags & EXT2_FLAG_FORCE)) {
 214                 features = fs->super->s_feature_incompat;
 215 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 216                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 217                         features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
 218 #endif
 219                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 220                         retval = EXT2_ET_UNSUPP_FEATURE;
 221                         goto cleanup;
 222                 }
 223
 224                 features = fs->super->s_feature_ro_compat;
 225 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 226                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 227                         features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
 228 #endif
 229                 if ((flags & EXT2_FLAG_RW) &&
 230                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 231                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 232                         goto cleanup;
 233                 }
 234
 235                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 236                     (fs->super->s_feature_incompat &
 237                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 238                         retval = EXT2_ET_UNSUPP_FEATURE;
 239                         goto cleanup;
 240                 }
 241         }
 242
 243         if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
 244             EXT2_MAX_BLOCK_LOG_SIZE) {
 245                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 246                 goto cleanup;
 247         }
 248         if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 249                                         EXT4_FEATURE_RO_COMPAT_BIGALLOC) &&
 250             (fs->super->s_log_block_size != fs->super->s_log_cluster_size)) {
 251                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 252                 goto cleanup;
 253         }
 254         fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 255         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 256                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 257                 goto cleanup;
 258         }
 259         fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
 260                 fs->super->s_log_block_size;
 261         if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
 262             EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
 263                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 264                 goto cleanup;
 265         }
 266         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 267                                        EXT2_INODE_SIZE(fs->super) +
 268                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 269                                       EXT2_BLOCK_SIZE(fs->super));
 270         if (block_size) {
 271                 if (block_size != fs->blocksize) {
 272                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 273                         goto cleanup;
 274                 }
 275         }
 276         /*
 277          * Set the blocksize to the filesystem's blocksize.
 278          */
 279         io_channel_set_blksize(fs->io, fs->blocksize);
 280
 281         /*
 282          * If this is an external journal device, don't try to read
 283          * the group descriptors, because they're not there.
 284          */
 285         if (fs->super->s_feature_incompat &
 286             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 287                 fs->group_desc_count = 0;
 288                 *ret_fs = fs;
 289                 return 0;
 290         }
 291
 292         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 293                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 294                 goto cleanup;
 295         }
 296
 297         /*
 298          * Read group descriptors
 299          */
 300         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 301         if (blocks_per_group == 0 ||
 302             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 303             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 304            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 305            fs->super->s_first_data_block >= ext2fs_blocks_count(fs->super)) {
 306                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 307                 goto cleanup;
 308         }
 309         fs->group_desc_count = ext2fs_div64_ceil(ext2fs_blocks_count(fs->super) -
 310                                                  fs->super->s_first_data_block,
 311                                                  blocks_per_group);
 312         if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 313             fs->super->s_inodes_count) {
 314                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 315                 goto cleanup;
 316         }
 317         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 318                                           EXT2_DESC_PER_BLOCK(fs->super));
 319         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 320                                 &fs->group_desc);
 321         if (retval)
 322                 goto cleanup;
 323         if (!group_block)
 324                 group_block = fs->super->s_first_data_block;
 325         dest = (char *) fs->group_desc;
 326         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 327         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 328                 first_meta_bg = fs->super->s_first_meta_bg;
 329         else
 330                 first_meta_bg = fs->desc_blocks;
 331         if (first_meta_bg) {
 332                 retval = io_channel_read_blk(fs->io, group_block+1,
 333                                              first_meta_bg, dest);
 334                 if (retval)
 335                         goto cleanup;
 336 #ifdef WORDS_BIGENDIAN
 337                 gdp = (struct ext2_group_desc *) dest;
 338                 for (j=0; j < groups_per_block*first_meta_bg; j++) {
 339                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 340                         ext2fs_swap_group_desc2(fs, gdp);
 341                 }
 342 #endif
 343                 dest += fs->blocksize*first_meta_bg;
 344         }
 345         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 346                 blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
 347                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 348                 if (retval)
 349                         goto cleanup;
 350 #ifdef WORDS_BIGENDIAN
 351                 for (j=0; j < groups_per_block; j++) {
 352                         /* The below happens to work... be careful. */
 353                         gdp = ext2fs_group_desc(fs, fs->group_desc, j);
 354                         ext2fs_swap_group_desc2(fs, gdp);
 355                 }
 356 #endif
 357                 dest += fs->blocksize;
 358         }
 359
 360         fs->stride = fs->super->s_raid_stride;
 361
 362         /*
 363          * If recovery is from backup superblock, Clear _UNININT flags &
 364          * reset bg_itable_unused to zero
 365          */
 366         if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 367                                         EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
 368                 dgrp_t group;
 369
 370                 for (group = 0; group < fs->group_desc_count; group++) {
 371                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
 372                         ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
 373                         ext2fs_bg_itable_unused_set(fs, group, 0);
 374                 }
 375                 ext2fs_mark_super_dirty(fs);
 376         }
 377
 378         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 379         *ret_fs = fs;
 380         return 0;
 381 cleanup:
 382         if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
 383                 *ret_fs = fs;
 384         else
 385                 ext2fs_free(fs);
 386         return retval;
 387 }
 388
 389 /*
 390  * Set/get the filesystem data I/O channel.
 391  *
 392  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 393  */
 394 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 395 {
 396         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 397                 return EXT2_ET_NOT_IMAGE_FILE;
 398         if (old_io) {
 399                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 400         }
 401         return 0;
 402 }
 403
 404 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 405 {
 406         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 407                 return EXT2_ET_NOT_IMAGE_FILE;
 408         fs->io = new_io ? new_io : fs->image_io;
 409         return 0;
 410 }
 411
 412 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 413 {
 414         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 415                 return EXT2_ET_NOT_IMAGE_FILE;
 416         fs->io = fs->image_io = new_io;
 417         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 418                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 419         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 420         return 0;
 421 }