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 Public
   8  * License.
   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              fs->super->s_blocks_count))
  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         blk_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         retval = manager->open(fs->device_name, io_flags, &fs->io);
 131         if (retval)
 132                 goto cleanup;
 133         if (io_options &&
 134             (retval = io_channel_set_options(fs->io, io_options)))
 135                 goto cleanup;
 136         fs->image_io = fs->io;
 137         fs->io->app_data = fs;
 138         retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
 139         if (retval)
 140                 goto cleanup;
 141         if (flags & EXT2_FLAG_IMAGE_FILE) {
 142                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 143                                         &fs->image_header);
 144                 if (retval)
 145                         goto cleanup;
 146                 retval = io_channel_read_blk(fs->io, 0,
 147                                              -(int)sizeof(struct ext2_image_hdr),
 148                                              fs->image_header);
 149                 if (retval)
 150                         goto cleanup;
 151                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 152                         return EXT2_ET_MAGIC_E2IMAGE;
 153                 superblock = 1;
 154                 block_size = fs->image_header->fs_blocksize;
 155         }
 156
 157         /*
 158          * If the user specifies a specific block # for the
 159          * superblock, then he/she must also specify the block size!
 160          * Otherwise, read the master superblock located at offset
 161          * SUPERBLOCK_OFFSET from the start of the partition.
 162          *
 163          * Note: we only save a backup copy of the superblock if we
 164          * are reading the superblock from the primary superblock location.
 165          */
 166         if (superblock) {
 167                 if (!block_size) {
 168                         retval = EXT2_ET_INVALID_ARGUMENT;
 169                         goto cleanup;
 170                 }
 171                 io_channel_set_blksize(fs->io, block_size);
 172                 group_block = superblock;
 173                 fs->orig_super = 0;
 174         } else {
 175                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 176                 superblock = 1;
 177                 group_block = 0;
 178                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 179                 if (retval)
 180                         goto cleanup;
 181         }
 182         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 183                                      fs->super);
 184         if (retval)
 185                 goto cleanup;
 186         if (fs->orig_super)
 187                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 188
 189 #ifdef WORDS_BIGENDIAN
 190         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 191         ext2fs_swap_super(fs->super);
 192 #else
 193         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 194                 retval = EXT2_ET_UNIMPLEMENTED;
 195                 goto cleanup;
 196         }
 197 #endif
 198
 199         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 200                 retval = EXT2_ET_BAD_MAGIC;
 201                 goto cleanup;
 202         }
 203         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 204                 retval = EXT2_ET_REV_TOO_HIGH;
 205                 goto cleanup;
 206         }
 207
 208         /*
 209          * Check for feature set incompatibility
 210          */
 211         if (!(flags & EXT2_FLAG_FORCE)) {
 212                 features = fs->super->s_feature_incompat;
 213 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 214                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 215                         features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
 216 #endif
 217                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 218                         retval = EXT2_ET_UNSUPP_FEATURE;
 219                         goto cleanup;
 220                 }
 221
 222                 features = fs->super->s_feature_ro_compat;
 223 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 224                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 225                         features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
 226 #endif
 227                 if ((flags & EXT2_FLAG_RW) &&
 228                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 229                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 230                         goto cleanup;
 231                 }
 232
 233                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 234                     (fs->super->s_feature_incompat &
 235                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 236                         retval = EXT2_ET_UNSUPP_FEATURE;
 237                         goto cleanup;
 238                 }
 239         }
 240
 241         if ((fs->super->s_log_block_size + EXT2_MIN_BLOCK_LOG_SIZE) >
 242             EXT2_MAX_BLOCK_LOG_SIZE) {
 243                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 244                 goto cleanup;
 245         }
 246         fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 247         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 248                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 249                 goto cleanup;
 250         }
 251         fs->fragsize = EXT2_FRAG_SIZE(fs->super);
 252         fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 253                                        EXT2_INODE_SIZE(fs->super) +
 254                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 255                                       EXT2_BLOCK_SIZE(fs->super));
 256         if (block_size) {
 257                 if (block_size != fs->blocksize) {
 258                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 259                         goto cleanup;
 260                 }
 261         }
 262         /*
 263          * Set the blocksize to the filesystem's blocksize.
 264          */
 265         io_channel_set_blksize(fs->io, fs->blocksize);
 266
 267         /*
 268          * If this is an external journal device, don't try to read
 269          * the group descriptors, because they're not there.
 270          */
 271         if (fs->super->s_feature_incompat &
 272             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 273                 fs->group_desc_count = 0;
 274                 *ret_fs = fs;
 275                 return 0;
 276         }
 277
 278         if (EXT2_INODES_PER_GROUP(fs->super) == 0) {
 279                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 280                 goto cleanup;
 281         }
 282
 283         /*
 284          * Read group descriptors
 285          */
 286         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 287         if (blocks_per_group == 0 ||
 288             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 289             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super) ||
 290            EXT2_DESC_PER_BLOCK(fs->super) == 0 ||
 291            fs->super->s_first_data_block >= fs->super->s_blocks_count) {
 292                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 293                 goto cleanup;
 294         }
 295         fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
 296                                                fs->super->s_first_data_block,
 297                                                blocks_per_group);
 298        if (fs->group_desc_count * EXT2_INODES_PER_GROUP(fs->super) !=
 299            fs->super->s_inodes_count) {
 300                retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 301                 goto cleanup;
 302        }
 303         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 304                                           EXT2_DESC_PER_BLOCK(fs->super));
 305         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 306                                 &fs->group_desc);
 307         if (retval)
 308                 goto cleanup;
 309         if (!group_block)
 310                 group_block = fs->super->s_first_data_block;
 311         dest = (char *) fs->group_desc;
 312         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 313         if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
 314                 first_meta_bg = fs->super->s_first_meta_bg;
 315         else
 316                 first_meta_bg = fs->desc_blocks;
 317         if (first_meta_bg) {
 318                 retval = io_channel_read_blk(fs->io, group_block+1,
 319                                              first_meta_bg, dest);
 320                 if (retval)
 321                         goto cleanup;
 322 #ifdef WORDS_BIGENDIAN
 323                 gdp = (struct ext2_group_desc *) dest;
 324                 for (j=0; j < groups_per_block*first_meta_bg; j++)
 325                         ext2fs_swap_group_desc(gdp++);
 326 #endif
 327                 dest += fs->blocksize*first_meta_bg;
 328         }
 329         for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
 330                 blk = ext2fs_descriptor_block_loc(fs, group_block, i);
 331                 retval = io_channel_read_blk64(fs->io, blk, 1, dest);
 332                 if (retval)
 333                         goto cleanup;
 334 #ifdef WORDS_BIGENDIAN
 335                 gdp = (struct ext2_group_desc *) dest;
 336                 for (j=0; j < groups_per_block; j++)
 337                         ext2fs_swap_group_desc(gdp++);
 338 #endif
 339                 dest += fs->blocksize;
 340         }
 341
 342         fs->stride = fs->super->s_raid_stride;
 343
 344         /*
 345          * If recovery is from backup superblock, Clear _UNININT flags &
 346          * reset bg_itable_unused to zero
 347          */
 348         if (superblock > 1 && EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 349                                         EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
 350                 struct ext2_group_desc *gd;
 351                 for (i = 0, gd = fs->group_desc; i < fs->group_desc_count;
 352                      i++, gd++) {
 353                         gd->bg_flags &= ~EXT2_BG_BLOCK_UNINIT;
 354                         gd->bg_flags &= ~EXT2_BG_INODE_UNINIT;
 355                         gd->bg_itable_unused = 0;
 356                 }
 357                 ext2fs_mark_super_dirty(fs);
 358         }
 359
 360         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 361         *ret_fs = fs;
 362         return 0;
 363 cleanup:
 364         if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
 365                 *ret_fs = fs;
 366         else
 367                 ext2fs_free(fs);
 368         return retval;
 369 }
 370
 371 /*
 372  * Set/get the filesystem data I/O channel.
 373  *
 374  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 375  */
 376 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 377 {
 378         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 379                 return EXT2_ET_NOT_IMAGE_FILE;
 380         if (old_io) {
 381                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 382         }
 383         return 0;
 384 }
 385
 386 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 387 {
 388         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 389                 return EXT2_ET_NOT_IMAGE_FILE;
 390         fs->io = new_io ? new_io : fs->image_io;
 391         return 0;
 392 }
 393
 394 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 395 {
 396         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 397                 return EXT2_ET_NOT_IMAGE_FILE;
 398         fs->io = fs->image_io = new_io;
 399         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 400                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 401         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 402         return 0;
 403 }