release/src/router/busybox/e2fsprogs/ext2fs/openfs.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * openfs.c --- open an ext2 filesystem
   4  *
   5  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   6  *
   7  * %Begin-Header%
   8  * This file may be redistributed under the terms of the GNU Public
   9  * License.
  10  * %End-Header%
  11  */
  12
  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 blk_t ext2fs_descriptor_block_loc(ext2_filsys fs, blk_t group_block, dgrp_t i)
  34 {
  35         int     bg;
  36         int     has_super = 0;
  37         int     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 = (fs->blocksize / sizeof (struct ext2_group_desc)) * i;
  44         if (ext2fs_bg_has_super(fs, bg))
  45                 has_super = 1;
  46         ret_blk = (fs->super->s_first_data_block + has_super +
  47                    (bg * fs->super->s_blocks_per_group));
  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              fs->super->s_blocks_count))
  59                 ret_blk += fs->super->s_blocks_per_group;
  60         return ret_blk;
  61 }
  62
  63 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  64                       unsigned int block_size, io_manager manager,
  65                       ext2_filsys *ret_fs)
  66 {
  67         return ext2fs_open2(name, 0, flags, superblock, block_size,
  68                             manager, ret_fs);
  69 }
  70
  71 /*
  72  *  Note: if superblock is non-zero, block-size must also be non-zero.
  73  *      Superblock and block_size can be zero to use the default size.
  74  *
  75  * Valid flags for ext2fs_open()
  76  *
  77  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
  78  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
  79  *                              features aren't supported.
  80  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
  81  */
  82 errcode_t ext2fs_open2(const char *name, const char *io_options,
  83                        int flags, int superblock,
  84                        unsigned int block_size, io_manager manager,
  85                        ext2_filsys *ret_fs)
  86 {
  87         ext2_filsys     fs;
  88         errcode_t       retval;
  89         unsigned long   i;
  90         int             groups_per_block, blocks_per_group;
  91         blk_t           group_block, blk;
  92         char            *dest, *cp;
  93 #if BB_BIG_ENDIAN
  94         int j;
  95         struct ext2_group_desc *gdp;
  96 #endif
  97
  98         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
  99
 100         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 101         if (retval)
 102                 return retval;
 103
 104         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 105         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 106         fs->flags = flags;
 107         fs->umask = 022;
 108         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 109         if (retval)
 110                 goto cleanup;
 111         strcpy(fs->device_name, name);
 112         cp = strchr(fs->device_name, '?');
 113         if (!io_options && cp) {
 114                 *cp++ = 0;
 115                 io_options = cp;
 116         }
 117
 118         retval = manager->open(fs->device_name,
 119                                (flags & EXT2_FLAG_RW) ? IO_FLAG_RW : 0,
 120                                &fs->io);
 121         if (retval)
 122                 goto cleanup;
 123         if (io_options &&
 124             (retval = io_channel_set_options(fs->io, io_options)))
 125                 goto cleanup;
 126         fs->image_io = fs->io;
 127         fs->io->app_data = fs;
 128         retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
 129         if (retval)
 130                 goto cleanup;
 131         if (flags & EXT2_FLAG_IMAGE_FILE) {
 132                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 133                                         &fs->image_header);
 134                 if (retval)
 135                         goto cleanup;
 136                 retval = io_channel_read_blk(fs->io, 0,
 137                                              -(int)sizeof(struct ext2_image_hdr),
 138                                              fs->image_header);
 139                 if (retval)
 140                         goto cleanup;
 141                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 142                         return EXT2_ET_MAGIC_E2IMAGE;
 143                 superblock = 1;
 144                 block_size = fs->image_header->fs_blocksize;
 145         }
 146
 147         /*
 148          * If the user specifies a specific block # for the
 149          * superblock, then he/she must also specify the block size!
 150          * Otherwise, read the master superblock located at offset
 151          * SUPERBLOCK_OFFSET from the start of the partition.
 152          *
 153          * Note: we only save a backup copy of the superblock if we
 154          * are reading the superblock from the primary superblock location.
 155          */
 156         if (superblock) {
 157                 if (!block_size) {
 158                         retval = EXT2_ET_INVALID_ARGUMENT;
 159                         goto cleanup;
 160                 }
 161                 io_channel_set_blksize(fs->io, block_size);
 162                 group_block = superblock;
 163                 fs->orig_super = 0;
 164         } else {
 165                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 166                 superblock = 1;
 167                 group_block = 0;
 168                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 169                 if (retval)
 170                         goto cleanup;
 171         }
 172         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 173                                      fs->super);
 174         if (retval)
 175                 goto cleanup;
 176         if (fs->orig_super)
 177                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 178
 179 #if BB_BIG_ENDIAN
 180         if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
 181             (fs->flags & EXT2_FLAG_SWAP_BYTES)) {
 182                 fs->flags |= EXT2_FLAG_SWAP_BYTES;
 183
 184                 ext2fs_swap_super(fs->super);
 185         }
 186 #endif
 187
 188         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 189                 retval = EXT2_ET_BAD_MAGIC;
 190                 goto cleanup;
 191         }
 192         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 193                 retval = EXT2_ET_REV_TOO_HIGH;
 194                 goto cleanup;
 195         }
 196
 197         /*
 198          * Check for feature set incompatibility
 199          */
 200         if (!(flags & EXT2_FLAG_FORCE)) {
 201                 if (fs->super->s_feature_incompat &
 202                     ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 203                         retval = EXT2_ET_UNSUPP_FEATURE;
 204                         goto cleanup;
 205                 }
 206                 if ((flags & EXT2_FLAG_RW) &&
 207                     (fs->super->s_feature_ro_compat &
 208                      ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 209                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 210                         goto cleanup;
 211                 }
 212                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 213                     (fs->super->s_feature_incompat &
 214                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 215                         retval = EXT2_ET_UNSUPP_FEATURE;
 216                         goto cleanup;
 217                 }
 218         }
 219
 220         fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 221         if (fs->blocksize == 0) {
 222                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 223                 goto cleanup;
 224         }
 225         fs->fragsize = EXT2_FRAG_SIZE(fs->super);
 226         fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
 227                                        EXT2_INODE_SIZE(fs->super) +
 228                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 229                                       EXT2_BLOCK_SIZE(fs->super));
 230         if (block_size) {
 231                 if (block_size != fs->blocksize) {
 232                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 233                         goto cleanup;
 234                 }
 235         }
 236         /*
 237          * Set the blocksize to the filesystem's blocksize.
 238          */
 239         io_channel_set_blksize(fs->io, fs->blocksize);
 240
 241         /*
 242          * If this is an external journal device, don't try to read
 243          * the group descriptors, because they're not there.
 244          */
 245         if (fs->super->s_feature_incompat &
 246             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 247                 fs->group_desc_count = 0;
 248                 *ret_fs = fs;
 249                 return 0;
 250         }
 251
 252         /*
 253          * Read group descriptors
 254          */
 255         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 256         if (blocks_per_group == 0 ||
 257             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 258             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
 259                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 260                 goto cleanup;
 261         }
 262         fs->group_desc_count = (fs->super->s_blocks_count -
 263                                 fs->super->s_first_data_block +
 264                                 blocks_per_group - 1) / blocks_per_group;
 265         fs->desc_blocks = (fs->group_desc_count +
 266                            EXT2_DESC_PER_BLOCK(fs->super) - 1)
 267                 / EXT2_DESC_PER_BLOCK(fs->super);
 268         retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize,
 269                                 &fs->group_desc);
 270         if (retval)
 271                 goto cleanup;
 272         if (!group_block)
 273                 group_block = fs->super->s_first_data_block;
 274         dest = (char *) fs->group_desc;
 275         groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
 276         for (i = 0; i < fs->desc_blocks; i++) {
 277                 blk = ext2fs_descriptor_block_loc(fs, group_block, i);
 278                 retval = io_channel_read_blk(fs->io, blk, 1, dest);
 279                 if (retval)
 280                         goto cleanup;
 281 #if BB_BIG_ENDIAN
 282                 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 283                         gdp = (struct ext2_group_desc *) dest;
 284                         for (j=0; j < groups_per_block; j++)
 285                                 ext2fs_swap_group_desc(gdp++);
 286                 }
 287 #endif
 288                 dest += fs->blocksize;
 289         }
 290
 291         *ret_fs = fs;
 292         return 0;
 293 cleanup:
 294         ext2fs_free(fs);
 295         return retval;
 296 }
 297
 298 /*
 299  * Set/get the filesystem data I/O channel.
 300  *
 301  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 302  */
 303 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 304 {
 305         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 306                 return EXT2_ET_NOT_IMAGE_FILE;
 307         if (old_io) {
 308                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 309         }
 310         return 0;
 311 }
 312
 313 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 314 {
 315         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 316                 return EXT2_ET_NOT_IMAGE_FILE;
 317         fs->io = new_io ? new_io : fs->image_io;
 318         return 0;
 319 }
 320
 321 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 322 {
 323         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 324                 return EXT2_ET_NOT_IMAGE_FILE;
 325         fs->io = fs->image_io = new_io;
 326         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 327                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 328         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 329         return 0;
 330 }