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 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 = fs->blocksize / sizeof(struct ext2_group_desc); 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 EXT2FS_ENABLE_SWAPFS 297 if (fs->flags & EXT2_FLAG_SWAP_BYTES) { 298 gdp = (struct ext2_group_desc *) dest; 299 for (j=0; j < groups_per_block; j++) 300 ext2fs_swap_group_desc(gdp++); 301 } 302 #endif 303 dest += fs->blocksize; 304 } 305 306 fs->stride = fs->super->s_raid_stride; 307 308 fs->flags &= ~EXT2_FLAG_NOFREE_ON_ERROR; 309 *ret_fs = fs; 310 return 0; 311 cleanup: 312 if (flags & EXT2_FLAG_NOFREE_ON_ERROR) 313 *ret_fs = fs; 314 else 315 ext2fs_free(fs); 316 return retval; 317 } 318 319 /* 320 * Set/get the filesystem data I/O channel. 321 * 322 * These functions are only valid if EXT2_FLAG_IMAGE_FILE is true. 323 */ 324 errcode_t ext2fs_get_data_io(ext2_filsys fs, io_channel *old_io) 325 { 326 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0) 327 return EXT2_ET_NOT_IMAGE_FILE; 328 if (old_io) { 329 *old_io = (fs->image_io == fs->io) ? 0 : fs->io; 330 } 331 return 0; 332 } 333 334 errcode_t ext2fs_set_data_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 = new_io ? new_io : fs->image_io; 339 return 0; 340 } 341 342 errcode_t ext2fs_rewrite_to_io(ext2_filsys fs, io_channel new_io) 343 { 344 if ((fs->flags & EXT2_FLAG_IMAGE_FILE) == 0) 345 return EXT2_ET_NOT_IMAGE_FILE; 346 fs->io = fs->image_io = new_io; 347 fs->flags |= EXT2_FLAG_DIRTY | EXT2_FLAG_RW | 348 EXT2_FLAG_BB_DIRTY | EXT2_FLAG_IB_DIRTY; 349 fs->flags &= ~EXT2_FLAG_IMAGE_FILE; 350 return 0; 351 } 352
