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 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  33 {
  34         int     bg;
  35         int     has_super = 0;
  36         int     ret_blk;
  37
  38         if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
  39             (i < fs->super->s_first_meta_bg))
  40                 return (group_block + i + 1);
  41
  42         bg = EXT2_DESC_PER_BLOCK(fs->super) * i;
  43         if (ext2fs_bg_has_super(fs, bg))
  44                 has_super = 1;
  45         ret_blk = ext2fs_group_first_block(fs, bg) + has_super;
  46         /*
  47          * If group_block is not the normal value, we're trying to use
  48          * the backup group descriptors and superblock --- so use the
  49          * alternate location of the second block group in the
  50          * metablock group.  Ideally we should be testing each bg
  51          * descriptor block individually for correctness, but we don't
  52          * have the infrastructure in place to do that.
  53          */
  54         if (group_block != fs->super->s_first_data_block &&
  55             ((ret_blk + fs->super->s_blocks_per_group) <
  56              fs->super->s_blocks_count))
  57                 ret_blk += fs->super->s_blocks_per_group;
  58         return ret_blk;
  59 }
  60
  61 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  62                       unsigned int block_size, io_manager manager,
  63                       ext2_filsys *ret_fs)
  64 {
  65         return ext2fs_open2(name, 0, flags, superblock, block_size,
  66                             manager, ret_fs);
  67 }
  68
  69 /*
  70  *  Note: if superblock is non-zero, block-size must also be non-zero.
  71  *      Superblock and block_size can be zero to use the default size.
  72  *
  73  * Valid flags for ext2fs_open()
  74  *
  75  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
  76  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
  77  *                              features aren't supported.
  78  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
  79  */
  80 errcode_t ext2fs_open2(const char *name, const char *io_options,
  81                        int flags, int superblock,
  82                        unsigned int block_size, io_manager manager,
  83                        ext2_filsys *ret_fs)
  84 {
  85         ext2_filsys     fs;
  86         errcode_t       retval;
  87         unsigned long   i;
  88         __u32           features;
  89         int             j, groups_per_block, blocks_per_group, io_flags;
  90         blk_t           group_block, blk;
  91         char            *dest, *cp;
  92         struct ext2_group_desc *gdp;
  93
  94         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
  95
  96         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
  97         if (retval)
  98                 return retval;
  99
 100         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 101         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 102         fs->flags = flags;
 103         /* don't overwrite sb backups unless flag is explicitly cleared */
 104         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 105         fs->umask = 022;
 106         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 107         if (retval)
 108                 goto cleanup;
 109         strcpy(fs->device_name, name);
 110         cp = strchr(fs->device_name, '?');
 111         if (!io_options && cp) {
 112                 *cp++ = 0;
 113                 io_options = cp;
 114         }
 115
 116         io_flags = 0;
 117         if (flags & EXT2_FLAG_RW)
 118                 io_flags |= IO_FLAG_RW;
 119         if (flags & EXT2_FLAG_EXCLUSIVE)
 120                 io_flags |= IO_FLAG_EXCLUSIVE;
 121         retval = manager->open(fs->device_name, io_flags, &fs->io);
 122         if (retval)
 123                 goto cleanup;
 124         if (io_options &&
 125             (retval = io_channel_set_options(fs->io, io_options)))
 126                 goto cleanup;
 127         fs->image_io = fs->io;
 128         fs->io->app_data = fs;
 129         retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
 130         if (retval)
 131                 goto cleanup;
 132         if (flags & EXT2_FLAG_IMAGE_FILE) {
 133                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 134                                         &fs->image_header);
 135                 if (retval)
 136                         goto cleanup;
 137                 retval = io_channel_read_blk(fs->io, 0,
 138                                              -(int)sizeof(struct ext2_image_hdr),
 139                                              fs->image_header);
 140                 if (retval)
 141                         goto cleanup;
 142                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 143                         return EXT2_ET_MAGIC_E2IMAGE;
 144                 superblock = 1;
 145                 block_size = fs->image_header->fs_blocksize;
 146         }
 147
 148         /*
 149          * If the user specifies a specific block # for the
 150          * superblock, then he/she must also specify the block size!
 151          * Otherwise, read the master superblock located at offset
 152          * SUPERBLOCK_OFFSET from the start of the partition.
 153          *
 154          * Note: we only save a backup copy of the superblock if we
 155          * are reading the superblock from the primary superblock location.
 156          */
 157         if (superblock) {
 158                 if (!block_size) {
 159                         retval = EXT2_ET_INVALID_ARGUMENT;
 160                         goto cleanup;
 161                 }
 162                 io_channel_set_blksize(fs->io, block_size);
 163                 group_block = superblock;
 164                 fs->orig_super = 0;
 165         } else {
 166                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 167                 superblock = 1;
 168                 group_block = 0;
 169                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 170                 if (retval)
 171                         goto cleanup;
 172         }
 173         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 174                                      fs->super);
 175         if (retval)
 176                 goto cleanup;
 177         if (fs->orig_super)
 178                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 179
 180 #ifdef WORDS_BIGENDIAN
 181         fs->flags |= EXT2_FLAG_SWAP_BYTES;
 182         ext2fs_swap_super(fs->super);
 183 #else
 184         if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 185                 retval = EXT2_ET_UNIMPLEMENTED;
 186                 goto cleanup;
 187         }
 188 #endif
 189
 190         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 191                 retval = EXT2_ET_BAD_MAGIC;
 192                 goto cleanup;
 193         }
 194         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 195                 retval = EXT2_ET_REV_TOO_HIGH;
 196                 goto cleanup;
 197         }
 198
 199         /*
 200          * Check for feature set incompatibility
 201          */
 202         if (!(flags & EXT2_FLAG_FORCE)) {
 203                 features = fs->super->s_feature_incompat;
 204 #ifdef EXT2_LIB_SOFTSUPP_INCOMPAT
 205                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 206                         features &= !EXT2_LIB_SOFTSUPP_INCOMPAT;
 207 #endif
 208                 if (features & ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 209                         retval = EXT2_ET_UNSUPP_FEATURE;
 210                         goto cleanup;
 211                 }
 212
 213                 features = fs->super->s_feature_ro_compat;
 214 #ifdef EXT2_LIB_SOFTSUPP_RO_COMPAT
 215                 if (flags & EXT2_FLAG_SOFTSUPP_FEATURES)
 216                         features &= !EXT2_LIB_SOFTSUPP_RO_COMPAT;
 217 #endif
 218                 if ((flags & EXT2_FLAG_RW) &&
 219                     (features & ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 220                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 221                         goto cleanup;
 222                 }
 223
 224                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 225                     (fs->super->s_feature_incompat &
 226                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 227                         retval = EXT2_ET_UNSUPP_FEATURE;
 228                         goto cleanup;
 229                 }
 230         }
 231
 232         fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 233         if (fs->blocksize == 0) {
 234                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 235                 goto cleanup;
 236         }
 237         if (EXT2_INODE_SIZE(fs->super) < EXT2_GOOD_OLD_INODE_SIZE) {
 238                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 239                 goto cleanup;
 240         }
 241         fs->fragsize = EXT2_FRAG_SIZE(fs->super);
 242         fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
 243                                        EXT2_INODE_SIZE(fs->super) +
 244                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 245                                       EXT2_BLOCK_SIZE(fs->super));
 246         if (block_size) {
 247                 if (block_size != fs->blocksize) {
 248                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 249                         goto cleanup;
 250                 }
 251         }
 252         /*
 253          * Set the blocksize to the filesystem's blocksize.
 254          */
 255         io_channel_set_blksize(fs->io, fs->blocksize);
 256
 257         /*
 258          * If this is an external journal device, don't try to read
 259          * the group descriptors, because they're not there.
 260          */
 261         if (fs->super->s_feature_incompat &
 262             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 263                 fs->group_desc_count = 0;
 264                 *ret_fs = fs;
 265                 return 0;
 266         }
 267
 268         /*
 269          * Read group descriptors
 270          */
 271         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 272         if (blocks_per_group == 0 ||
 273             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 274             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
 275                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 276                 goto cleanup;
 277         }
 278         fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
 279                                                fs->super->s_first_data_block,
 280                                                blocks_per_group);
 281         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 282                                           EXT2_DESC_PER_BLOCK(fs->super));
 283         retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
 284                                 &fs->group_desc);
 285         if (retval)
 286                 goto cleanup;
 287         if (!group_block)
 288                 group_block = fs->super->s_first_data_block;
 289         dest = (char *) fs->group_desc;
 290         groups_per_block = EXT2_DESC_PER_BLOCK(fs->super);
 291         for (i=0 ; i < fs->desc_blocks; i++) {
 292                 blk = ext2fs_descriptor_block_loc(fs, group_block, i);
 293                 retval = io_channel_read_blk(fs->io, blk, 1, dest);
 294                 if (retval)
 295                         goto cleanup;
 296 #ifdef WORDS_BIGENDIAN
 297                 gdp = (struct ext2_group_desc *) dest;
 298                 for (j=0; j < groups_per_block; j++)
 299                         ext2fs_swap_group_desc(gdp++);
 300 #endif
 301                 dest += fs->blocksize;
 302         }
 303
 304         fs->stride = fs->super->s_raid_stride;
 305
 306         fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR;
 307         *ret_fs = fs;
 308         return 0;
 309 cleanup:
 310         if (flags & EXT2_FLAG_NOFREE_ON_ERROR)
 311                 *ret_fs = fs;
 312         else
 313                 ext2fs_free(fs);
 314         return retval;
 315 }
 316
 317 /*
 318  * Set/get the filesystem data I/O channel.
 319  *
 320  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 321  */
 322 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 323 {
 324         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 325                 return EXT2_ET_NOT_IMAGE_FILE;
 326         if (old_io) {
 327                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 328         }
 329         return 0;
 330 }
 331
 332 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 333 {
 334         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 335                 return EXT2_ET_NOT_IMAGE_FILE;
 336         fs->io = new_io ? new_io : fs->image_io;
 337         return 0;
 338 }
 339
 340 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 341 {
 342         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 343                 return EXT2_ET_NOT_IMAGE_FILE;
 344         fs->io = fs->image_io = new_io;
 345         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 346                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 347         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 348         return 0;
 349 }