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 = (fs->blocksize / sizeof (struct ext2_group_desc)) * i;
  43         if (ext2fs_bg_has_super(fs, bg))
  44                 has_super = 1;
  45         ret_blk = (fs->super->s_first_data_block + has_super +
  46                    (bg * fs->super->s_blocks_per_group));
  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 errcode_t ext2fs_open(const char *name, int flags, int superblock,
  63                       unsigned int block_size, io_manager manager,
  64                       ext2_filsys *ret_fs)
  65 {
  66         return ext2fs_open2(name, 0, flags, superblock, block_size,
  67                             manager, ret_fs);
  68 }
  69
  70 /*
  71  *  Note: if superblock is non-zero, block-size must also be non-zero.
  72  *      Superblock and block_size can be zero to use the default size.
  73  *
  74  * Valid flags for ext2fs_open()
  75  *
  76  *      EXT2_FLAG_RW    - Open the filesystem for read/write.
  77  *      EXT2_FLAG_FORCE - Open the filesystem even if some of the
  78  *                              features aren't supported.
  79  *      EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device
  80  */
  81 errcode_t ext2fs_open2(const char *name, const char *io_options,
  82                        int flags, int superblock,
  83                        unsigned int block_size, io_manager manager,
  84                        ext2_filsys *ret_fs)
  85 {
  86         ext2_filsys     fs;
  87         errcode_t       retval;
  88         unsigned long   i;
  89         __u32           features;
  90         int             j, groups_per_block, blocks_per_group, io_flags;
  91         blk_t           group_block, blk;
  92         char            *dest, *cp;
  93         struct ext2_group_desc *gdp;
  94
  95         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
  96
  97         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
  98         if (retval)
  99                 return retval;
 100
 101         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 102         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 103         fs->flags = flags;
 104         /* don't overwrite sb backups unless flag is explicitly cleared */
 105         fs->flags |= EXT2_FLAG_MASTER_SB_ONLY;
 106         fs->umask = 022;
 107         retval = ext2fs_get_mem(strlen(name)+1, &fs->device_name);
 108         if (retval)
 109                 goto cleanup;
 110         strcpy(fs->device_name, name);
 111         cp = strchr(fs->device_name, '?');
 112         if (!io_options && cp) {
 113                 *cp++ = 0;
 114                 io_options = cp;
 115         }
 116
 117         io_flags = 0;
 118         if (flags & EXT2_FLAG_RW)
 119                 io_flags |= IO_FLAG_RW;
 120         if (flags & EXT2_FLAG_EXCLUSIVE)
 121                 io_flags |= IO_FLAG_EXCLUSIVE;
 122         retval = manager->open(fs->device_name, io_flags, &fs->io);
 123         if (retval)
 124                 goto cleanup;
 125         if (io_options &&
 126             (retval = io_channel_set_options(fs->io, io_options)))
 127                 goto cleanup;
 128         fs->image_io = fs->io;
 129         fs->io->app_data = fs;
 130         retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
 131         if (retval)
 132                 goto cleanup;
 133         if (flags & EXT2_FLAG_IMAGE_FILE) {
 134                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 135                                         &fs->image_header);
 136                 if (retval)
 137                         goto cleanup;
 138                 retval = io_channel_read_blk(fs->io, 0,
 139                                              -(int)sizeof(struct ext2_image_hdr),
 140                                              fs->image_header);
 141                 if (retval)
 142                         goto cleanup;
 143                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 144                         return EXT2_ET_MAGIC_E2IMAGE;
 145                 superblock = 1;
 146                 block_size = fs->image_header->fs_blocksize;
 147         }
 148
 149         /*
 150          * If the user specifies a specific block # for the
 151          * superblock, then he/she must also specify the block size!
 152          * Otherwise, read the master superblock located at offset
 153          * SUPERBLOCK_OFFSET from the start of the partition.
 154          *
 155          * Note: we only save a backup copy of the superblock if we
 156          * are reading the superblock from the primary superblock location.
 157          */
 158         if (superblock) {
 159                 if (!block_size) {
 160                         retval = EXT2_ET_INVALID_ARGUMENT;
 161                         goto cleanup;
 162                 }
 163                 io_channel_set_blksize(fs->io, block_size);
 164                 group_block = superblock;
 165                 fs->orig_super = 0;
 166         } else {
 167                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 168                 superblock = 1;
 169                 group_block = 0;
 170                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 171                 if (retval)
 172                         goto cleanup;
 173         }
 174         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 175                                      fs->super);
 176         if (retval)
 177                 goto cleanup;
 178         if (fs->orig_super)
 179                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 180
 181 #ifdef EXT2FS_ENABLE_SWAPFS
 182         if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
 183             (fs->flags & EXT2_FLAG_SWAP_BYTES)) {
 184                 fs->flags |= EXT2_FLAG_SWAP_BYTES;
 185
 186                 ext2fs_swap_super(fs->super);
 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         fs->fragsize = EXT2_FRAG_SIZE(fs->super);
 238         fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
 239                                        EXT2_INODE_SIZE(fs->super) +
 240                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 241                                       EXT2_BLOCK_SIZE(fs->super));
 242         if (block_size) {
 243                 if (block_size != fs->blocksize) {
 244                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 245                         goto cleanup;
 246                 }
 247         }
 248         /*
 249          * Set the blocksize to the filesystem's blocksize.
 250          */
 251         io_channel_set_blksize(fs->io, fs->blocksize);
 252
 253         /*
 254          * If this is an external journal device, don't try to read
 255          * the group descriptors, because they're not there.
 256          */
 257         if (fs->super->s_feature_incompat &
 258             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 259                 fs->group_desc_count = 0;
 260                 *ret_fs = fs;
 261                 return 0;
 262         }
 263
 264         /*
 265          * Read group descriptors
 266          */
 267         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 268         if (blocks_per_group == 0 ||
 269             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 270             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
 271                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 272                 goto cleanup;
 273         }
 274         fs->group_desc_count = ext2fs_div_ceil(fs->super->s_blocks_count -
 275                                                fs->super->s_first_data_block,
 276                                                blocks_per_group);
 277         fs->desc_blocks = ext2fs_div_ceil(fs->group_desc_count,
 278                                           EXT2_DESC_PER_BLOCK(fs->super));
 279         retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize,
 280                                 &fs->group_desc);
 281         if (retval)
 282                 goto cleanup;
 283         if (!group_block)
 284                 group_block = fs->super->s_first_data_block;
 285         dest = (char *) fs->group_desc;
 286         groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
 287         for (i=0 ; i < fs->desc_blocks; i++) {
 288                 blk = ext2fs_descriptor_block_loc(fs, group_block, i);
 289                 retval = io_channel_read_blk(fs->io, blk, 1, dest);
 290                 if (retval)
 291                         goto cleanup;
 292 #ifdef EXT2FS_ENABLE_SWAPFS
 293                 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 294                         gdp = (struct ext2_group_desc *) dest;
 295                         for (j=0; j < groups_per_block; j++)
 296                                 ext2fs_swap_group_desc(gdp++);
 297                 }
 298 #endif
 299                 dest += fs->blocksize;
 300         }
 301
 302         fs->stride = fs->super->s_raid_stride;
 303
 304         *ret_fs = fs;
 305         return 0;
 306 cleanup:
 307         ext2fs_free(fs);
 308         return retval;
 309 }
 310
 311 /*
 312  * Set/get the filesystem data I/O channel.
 313  *
 314  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 315  */
 316 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 317 {
 318         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 319                 return EXT2_ET_NOT_IMAGE_FILE;
 320         if (old_io) {
 321                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 322         }
 323         return 0;
 324 }
 325
 326 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 327 {
 328         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 329                 return EXT2_ET_NOT_IMAGE_FILE;
 330         fs->io = new_io ? new_io : fs->image_io;
 331         return 0;
 332 }
 333
 334 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 335 {
 336         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 337                 return EXT2_ET_NOT_IMAGE_FILE;
 338         fs->io = fs->image_io = new_io;
 339         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 340                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 341         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 342         return 0;
 343 }