e2fsprogs/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         int             groups_per_block, blocks_per_group;
  90         blk_t           group_block, blk;
  91         char            *dest, *cp;
  92 #ifdef EXT2FS_ENABLE_SWAPFS
  93         int j;
  94         struct ext2_group_desc *gdp;
  95 #endif
  96
  97         EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
  98
  99         retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
 100         if (retval)
 101                 return retval;
 102
 103         memset(fs, 0, sizeof(struct struct_ext2_filsys));
 104         fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS;
 105         fs->flags = flags;
 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         retval = manager->open(fs->device_name,
 118                                (flags & EXT2_FLAG_RW) ? IO_FLAG_RW : 0,
 119                                &fs->io);
 120         if (retval)
 121                 goto cleanup;
 122         if (io_options &&
 123             (retval = io_channel_set_options(fs->io, io_options)))
 124                 goto cleanup;
 125         fs->image_io = fs->io;
 126         fs->io->app_data = fs;
 127         retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
 128         if (retval)
 129                 goto cleanup;
 130         if (flags & EXT2_FLAG_IMAGE_FILE) {
 131                 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr),
 132                                         &fs->image_header);
 133                 if (retval)
 134                         goto cleanup;
 135                 retval = io_channel_read_blk(fs->io, 0,
 136                                              -(int)sizeof(struct ext2_image_hdr),
 137                                              fs->image_header);
 138                 if (retval)
 139                         goto cleanup;
 140                 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE)
 141                         return EXT2_ET_MAGIC_E2IMAGE;
 142                 superblock = 1;
 143                 block_size = fs->image_header->fs_blocksize;
 144         }
 145
 146         /*
 147          * If the user specifies a specific block # for the
 148          * superblock, then he/she must also specify the block size!
 149          * Otherwise, read the master superblock located at offset
 150          * SUPERBLOCK_OFFSET from the start of the partition.
 151          *
 152          * Note: we only save a backup copy of the superblock if we
 153          * are reading the superblock from the primary superblock location.
 154          */
 155         if (superblock) {
 156                 if (!block_size) {
 157                         retval = EXT2_ET_INVALID_ARGUMENT;
 158                         goto cleanup;
 159                 }
 160                 io_channel_set_blksize(fs->io, block_size);
 161                 group_block = superblock;
 162                 fs->orig_super = 0;
 163         } else {
 164                 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
 165                 superblock = 1;
 166                 group_block = 0;
 167                 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
 168                 if (retval)
 169                         goto cleanup;
 170         }
 171         retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE,
 172                                      fs->super);
 173         if (retval)
 174                 goto cleanup;
 175         if (fs->orig_super)
 176                 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE);
 177
 178 #ifdef EXT2FS_ENABLE_SWAPFS
 179         if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) ||
 180             (fs->flags & EXT2_FLAG_SWAP_BYTES)) {
 181                 fs->flags |= EXT2_FLAG_SWAP_BYTES;
 182
 183                 ext2fs_swap_super(fs->super);
 184         }
 185 #endif
 186
 187         if (fs->super->s_magic != EXT2_SUPER_MAGIC) {
 188                 retval = EXT2_ET_BAD_MAGIC;
 189                 goto cleanup;
 190         }
 191         if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) {
 192                 retval = EXT2_ET_REV_TOO_HIGH;
 193                 goto cleanup;
 194         }
 195
 196         /*
 197          * Check for feature set incompatibility
 198          */
 199         if (!(flags & EXT2_FLAG_FORCE)) {
 200                 if (fs->super->s_feature_incompat &
 201                     ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) {
 202                         retval = EXT2_ET_UNSUPP_FEATURE;
 203                         goto cleanup;
 204                 }
 205                 if ((flags & EXT2_FLAG_RW) &&
 206                     (fs->super->s_feature_ro_compat &
 207                      ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) {
 208                         retval = EXT2_ET_RO_UNSUPP_FEATURE;
 209                         goto cleanup;
 210                 }
 211                 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) &&
 212                     (fs->super->s_feature_incompat &
 213                      EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
 214                         retval = EXT2_ET_UNSUPP_FEATURE;
 215                         goto cleanup;
 216                 }
 217         }
 218
 219         fs->blocksize = EXT2_BLOCK_SIZE(fs->super);
 220         if (fs->blocksize == 0) {
 221                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 222                 goto cleanup;
 223         }
 224         fs->fragsize = EXT2_FRAG_SIZE(fs->super);
 225         fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group *
 226                                        EXT2_INODE_SIZE(fs->super) +
 227                                        EXT2_BLOCK_SIZE(fs->super) - 1) /
 228                                       EXT2_BLOCK_SIZE(fs->super));
 229         if (block_size) {
 230                 if (block_size != fs->blocksize) {
 231                         retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE;
 232                         goto cleanup;
 233                 }
 234         }
 235         /*
 236          * Set the blocksize to the filesystem's blocksize.
 237          */
 238         io_channel_set_blksize(fs->io, fs->blocksize);
 239
 240         /*
 241          * If this is an external journal device, don't try to read
 242          * the group descriptors, because they're not there.
 243          */
 244         if (fs->super->s_feature_incompat &
 245             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) {
 246                 fs->group_desc_count = 0;
 247                 *ret_fs = fs;
 248                 return 0;
 249         }
 250
 251         /*
 252          * Read group descriptors
 253          */
 254         blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super);
 255         if (blocks_per_group == 0 ||
 256             blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) ||
 257             fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) {
 258                 retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 259                 goto cleanup;
 260         }
 261         fs->group_desc_count = (fs->super->s_blocks_count -
 262                                 fs->super->s_first_data_block +
 263                                 blocks_per_group - 1) / blocks_per_group;
 264         fs->desc_blocks = (fs->group_desc_count +
 265                            EXT2_DESC_PER_BLOCK(fs->super) - 1)
 266                 / EXT2_DESC_PER_BLOCK(fs->super);
 267         retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize,
 268                                 &fs->group_desc);
 269         if (retval)
 270                 goto cleanup;
 271         if (!group_block)
 272                 group_block = fs->super->s_first_data_block;
 273         dest = (char *) fs->group_desc;
 274         groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
 275         for (i=0 ; i < fs->desc_blocks; i++) {
 276                 blk = ext2fs_descriptor_block_loc(fs, group_block, i);
 277                 retval = io_channel_read_blk(fs->io, blk, 1, dest);
 278                 if (retval)
 279                         goto cleanup;
 280 #ifdef EXT2FS_ENABLE_SWAPFS
 281                 if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
 282                         gdp = (struct ext2_group_desc *) dest;
 283                         for (j=0; j < groups_per_block; j++)
 284                                 ext2fs_swap_group_desc(gdp++);
 285                 }
 286 #endif
 287                 dest += fs->blocksize;
 288         }
 289
 290         *ret_fs = fs;
 291         return 0;
 292 cleanup:
 293         ext2fs_free(fs);
 294         return retval;
 295 }
 296
 297 /*
 298  * Set/get the filesystem data I/O channel.
 299  *
 300  * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true.
 301  */
 302 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io)
 303 {
 304         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 305                 return EXT2_ET_NOT_IMAGE_FILE;
 306         if (old_io) {
 307                 *old_io = (fs->image_io == fs->io) ? 0 : fs->io;
 308         }
 309         return 0;
 310 }
 311
 312 errcode_t ext2fs_set_data_io(ext2_filsys fs, io_channel new_io)
 313 {
 314         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 315                 return EXT2_ET_NOT_IMAGE_FILE;
 316         fs->io = new_io ? new_io : fs->image_io;
 317         return 0;
 318 }
 319
 320 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io)
 321 {
 322         if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0)
 323                 return EXT2_ET_NOT_IMAGE_FILE;
 324         fs->io = fs->image_io = new_io;
 325         fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW |
 326                 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY;
 327         fs->flags &= ~EXT2_FLAG_IMAGE_FILE;
 328         return 0;
 329 }