openfs.c revision c046ac7f2e4c53e20cf1e909bbe511f91074b396
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 32blk_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 37 if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) || 38 (i < fs->super->s_first_meta_bg)) 39 return (group_block + i + 1); 40 41 bg = (fs->blocksize / sizeof (struct ext2_group_desc)) * i; 42 if (ext2fs_bg_has_super(fs, bg)) 43 has_super = 1; 44 return (fs->super->s_first_data_block + has_super + 45 (bg * fs->super->s_blocks_per_group)); 46} 47 48/* 49 * Note: if superblock is non-zero, block-size must also be non-zero. 50 * Superblock and block_size can be zero to use the default size. 51 * 52 * Valid flags for ext2fs_open() 53 * 54 * EXT2_FLAG_RW - Open the filesystem for read/write. 55 * EXT2_FLAG_FORCE - Open the filesystem even if some of the 56 * features aren't supported. 57 * EXT2_FLAG_JOURNAL_DEV_OK - Open an ext3 journal device 58 */ 59errcode_t ext2fs_open(const char *name, int flags, int superblock, 60 int block_size, io_manager manager, ext2_filsys *ret_fs) 61{ 62 ext2_filsys fs; 63 errcode_t retval; 64 int i, j, groups_per_block, blocks_per_group; 65 blk_t group_block, blk; 66 char *dest; 67 struct ext2_group_desc *gdp; 68 69 EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER); 70 71 retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), 72 (void **) &fs); 73 if (retval) 74 return retval; 75 76 memset(fs, 0, sizeof(struct struct_ext2_filsys)); 77 fs->magic = EXT2_ET_MAGIC_EXT2FS_FILSYS; 78 fs->flags = flags; 79 fs->umask = 022; 80 retval = manager->open(name, (flags & EXT2_FLAG_RW) ? IO_FLAG_RW : 0, 81 &fs->io); 82 if (retval) 83 goto cleanup; 84 fs->io->app_data = fs; 85 retval = ext2fs_get_mem(strlen(name)+1, (void **) &fs->device_name); 86 if (retval) 87 goto cleanup; 88 strcpy(fs->device_name, name); 89 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, (void **) &fs->super); 90 if (retval) 91 goto cleanup; 92 if (flags & EXT2_FLAG_IMAGE_FILE) { 93 retval = ext2fs_get_mem(sizeof(struct ext2_image_hdr), 94 (void **) &fs->image_header); 95 if (retval) 96 goto cleanup; 97 retval = io_channel_read_blk(fs->io, 0, 98 -sizeof(struct ext2_image_hdr), 99 fs->image_header); 100 if (retval) 101 goto cleanup; 102 if (fs->image_header->magic_number != EXT2_ET_MAGIC_E2IMAGE) 103 return EXT2_ET_MAGIC_E2IMAGE; 104 superblock = 1; 105 block_size = fs->image_header->fs_blocksize; 106 } 107 108 /* 109 * If the user specifies a specific block # for the 110 * superblock, then he/she must also specify the block size! 111 * Otherwise, read the master superblock located at offset 112 * SUPERBLOCK_OFFSET from the start of the partition. 113 * 114 * Note: we only save a backup copy of the superblock if we 115 * are reading the superblock from the primary superblock location. 116 */ 117 if (superblock) { 118 if (!block_size) { 119 retval = EXT2_ET_INVALID_ARGUMENT; 120 goto cleanup; 121 } 122 io_channel_set_blksize(fs->io, block_size); 123 group_block = superblock + 1; 124 fs->orig_super = 0; 125 } else { 126 io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET); 127 superblock = 1; 128 group_block = 0; 129 retval = ext2fs_get_mem(SUPERBLOCK_SIZE, 130 (void **) &fs->orig_super); 131 if (retval) 132 goto cleanup; 133 } 134 retval = io_channel_read_blk(fs->io, superblock, -SUPERBLOCK_SIZE, 135 fs->super); 136 if (retval) 137 goto cleanup; 138 if (fs->orig_super) 139 memcpy(fs->orig_super, fs->super, SUPERBLOCK_SIZE); 140 141#ifdef EXT2FS_ENABLE_SWAPFS 142 if ((fs->super->s_magic == ext2fs_swab16(EXT2_SUPER_MAGIC)) || 143 (fs->flags & EXT2_FLAG_SWAP_BYTES)) { 144 fs->flags |= EXT2_FLAG_SWAP_BYTES; 145 146 ext2fs_swap_super(fs->super); 147 } 148#endif 149 150 if (fs->super->s_magic != EXT2_SUPER_MAGIC) { 151 retval = EXT2_ET_BAD_MAGIC; 152 goto cleanup; 153 } 154 if (fs->super->s_rev_level > EXT2_LIB_CURRENT_REV) { 155 retval = EXT2_ET_REV_TOO_HIGH; 156 goto cleanup; 157 } 158 159 /* 160 * Check for feature set incompatibility 161 */ 162 if (!(flags & EXT2_FLAG_FORCE)) { 163 if (fs->super->s_feature_incompat & 164 ~EXT2_LIB_FEATURE_INCOMPAT_SUPP) { 165 retval = EXT2_ET_UNSUPP_FEATURE; 166 goto cleanup; 167 } 168 if ((flags & EXT2_FLAG_RW) && 169 (fs->super->s_feature_ro_compat & 170 ~EXT2_LIB_FEATURE_RO_COMPAT_SUPP)) { 171 retval = EXT2_ET_RO_UNSUPP_FEATURE; 172 goto cleanup; 173 } 174 if (!(flags & EXT2_FLAG_JOURNAL_DEV_OK) && 175 (fs->super->s_feature_incompat & 176 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) { 177 retval = EXT2_ET_UNSUPP_FEATURE; 178 goto cleanup; 179 } 180 } 181 182 fs->blocksize = EXT2_BLOCK_SIZE(fs->super); 183 if (fs->blocksize == 0) { 184 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 185 goto cleanup; 186 } 187 fs->fragsize = EXT2_FRAG_SIZE(fs->super); 188 fs->inode_blocks_per_group = ((fs->super->s_inodes_per_group * 189 EXT2_INODE_SIZE(fs->super) + 190 EXT2_BLOCK_SIZE(fs->super) - 1) / 191 EXT2_BLOCK_SIZE(fs->super)); 192 if (block_size) { 193 if (block_size != fs->blocksize) { 194 retval = EXT2_ET_UNEXPECTED_BLOCK_SIZE; 195 goto cleanup; 196 } 197 } 198 /* 199 * Set the blocksize to the filesystem's blocksize. 200 */ 201 io_channel_set_blksize(fs->io, fs->blocksize); 202 203 /* 204 * If this is an external journal device, don't try to read 205 * the group descriptors, because they're not there. 206 */ 207 if (fs->super->s_feature_incompat & 208 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV) { 209 fs->group_desc_count = 0; 210 *ret_fs = fs; 211 return 0; 212 } 213 214 /* 215 * Read group descriptors 216 */ 217 blocks_per_group = EXT2_BLOCKS_PER_GROUP(fs->super); 218 if (blocks_per_group == 0 || 219 blocks_per_group > EXT2_MAX_BLOCKS_PER_GROUP(fs->super) || 220 fs->inode_blocks_per_group > EXT2_MAX_INODES_PER_GROUP(fs->super)) { 221 retval = EXT2_ET_CORRUPT_SUPERBLOCK; 222 goto cleanup; 223 } 224 fs->group_desc_count = (fs->super->s_blocks_count - 225 fs->super->s_first_data_block + 226 blocks_per_group - 1) / blocks_per_group; 227 fs->desc_blocks = (fs->group_desc_count + 228 EXT2_DESC_PER_BLOCK(fs->super) - 1) 229 / EXT2_DESC_PER_BLOCK(fs->super); 230 retval = ext2fs_get_mem(fs->desc_blocks * fs->blocksize, 231 (void **) &fs->group_desc); 232 if (retval) 233 goto cleanup; 234 if (!group_block) 235 group_block = fs->super->s_first_data_block; 236 dest = (char *) fs->group_desc; 237 groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc); 238 for (i=0 ; i < fs->desc_blocks; i++) { 239 blk = ext2fs_descriptor_block_loc(fs, group_block, i); 240 retval = io_channel_read_blk(fs->io, blk, 1, dest); 241 if (retval) 242 goto cleanup; 243#ifdef EXT2FS_ENABLE_SWAPFS 244 if (fs->flags & EXT2_FLAG_SWAP_BYTES) { 245 gdp = (struct ext2_group_desc *) dest; 246 for (j=0; j < groups_per_block; j++) 247 ext2fs_swap_group_desc(gdp++); 248 } 249#endif 250 dest += fs->blocksize; 251 } 252 253 *ret_fs = fs; 254 return 0; 255cleanup: 256 ext2fs_free(fs); 257 return retval; 258} 259 260