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 33blk_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 63errcode_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 */ 82errcode_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; 293cleanup: 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 */ 303errcode_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 313errcode_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 321errcode_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} 331