fs/ext2/ext2_utils.c

   1 /*
   2  *
   3  * (c) 2008-2009 Laurent Vivier <Laurent@lvivier.info>
   4  *
   5  * This file has been copied from EMILE, http://emile.sf.net
   6  *
   7  */
   8
   9 #include "libext2.h"
  10 #include "ext2_utils.h"
  11 #include "libopenbios/bindings.h"
  12 #include "libc/diskio.h"
  13 #include "libc/byteorder.h"
  14
  15 int ext2_probe(int fd, long long offset)
  16 {
  17         struct ext2_super_block *super;
  18
  19         super = (struct ext2_super_block*)malloc(sizeof(struct ext2_super_block));
  20         seek_io(fd, 2 * 512 + offset);
  21         read_io(fd, super, sizeof (*super));
  22
  23         if (__le16_to_cpu(super->s_magic) != EXT2_SUPER_MAGIC) {
  24                 free(super);
  25                 return 0;
  26         }
  27
  28         free(super);
  29         return -1;
  30 }
  31
  32 void ext2_get_super(int fd, struct ext2_super_block *super)
  33 {
  34         seek_io(fd, 2 * 512);
  35         read_io(fd, super, sizeof (*super));
  36
  37         super->s_inodes_count = __le32_to_cpu(super->s_inodes_count);
  38         super->s_blocks_count = __le32_to_cpu(super->s_blocks_count);
  39         super->s_r_blocks_count = __le32_to_cpu(super->s_r_blocks_count);
  40         super->s_free_blocks_count = __le32_to_cpu(super->s_free_blocks_count);
  41         super->s_free_inodes_count = __le32_to_cpu(super->s_free_inodes_count);
  42         super->s_first_data_block = __le32_to_cpu(super->s_first_data_block);
  43         super->s_log_block_size = __le32_to_cpu(super->s_log_block_size);
  44         super->s_log_frag_size = __le32_to_cpu(super->s_log_frag_size);
  45         super->s_blocks_per_group = __le32_to_cpu(super->s_blocks_per_group);
  46         super->s_frags_per_group = __le32_to_cpu(super->s_frags_per_group);
  47         super->s_inodes_per_group = __le32_to_cpu(super->s_inodes_per_group);
  48         super->s_mtime = __le32_to_cpu(super->s_mtime);
  49         super->s_wtime = __le32_to_cpu(super->s_wtime);
  50         super->s_mnt_count = __le16_to_cpu(super->s_mnt_count);
  51         super->s_max_mnt_count = __le16_to_cpu(super->s_max_mnt_count);
  52         super->s_magic = __le16_to_cpu(super->s_magic);
  53         super->s_state = __le16_to_cpu(super->s_state);
  54         super->s_errors = __le16_to_cpu(super->s_errors);
  55         super->s_minor_rev_level = __le16_to_cpu(super->s_minor_rev_level);
  56         super->s_lastcheck = __le32_to_cpu(super->s_lastcheck);
  57         super->s_checkinterval = __le32_to_cpu(super->s_checkinterval);
  58         super->s_creator_os = __le32_to_cpu(super->s_creator_os);
  59         super->s_rev_level = __le32_to_cpu(super->s_rev_level);
  60         super->s_def_resuid = __le16_to_cpu(super->s_def_resuid);
  61         super->s_def_resgid = __le16_to_cpu(super->s_def_resgid);
  62         super->s_first_ino = __le32_to_cpu(super->s_first_ino);
  63         super->s_inode_size = __le16_to_cpu(super->s_inode_size);
  64         super->s_block_group_nr = __le16_to_cpu(super->s_block_group_nr);
  65         super->s_feature_compat = __le32_to_cpu(super->s_feature_compat);
  66         super->s_feature_incompat = __le32_to_cpu(super->s_feature_incompat);
  67         super->s_feature_ro_compat = __le32_to_cpu(super->s_feature_ro_compat);
  68         super->s_algorithm_usage_bitmap =
  69                                 __le32_to_cpu(super->s_algorithm_usage_bitmap);
  70         super->s_journal_inum = __le32_to_cpu(super->s_journal_inum);
  71         super->s_journal_dev = __le32_to_cpu(super->s_journal_dev);
  72         super->s_last_orphan = __le32_to_cpu(super->s_last_orphan);
  73         super->s_hash_seed[0] = __le32_to_cpu(super->s_hash_seed[0]);
  74         super->s_hash_seed[1] = __le32_to_cpu(super->s_hash_seed[1]);
  75         super->s_hash_seed[2] = __le32_to_cpu(super->s_hash_seed[2]);
  76         super->s_hash_seed[3] = __le32_to_cpu(super->s_hash_seed[3]);
  77         super->s_default_mount_opts =
  78                                 __le32_to_cpu(super->s_default_mount_opts);
  79         super->s_first_meta_bg = __le32_to_cpu(super->s_first_meta_bg);
  80 }
  81
  82 void ext2_read_block(ext2_VOLUME* volume, unsigned int fsblock)
  83 {
  84         long long offset;
  85
  86         if (fsblock == volume->current)
  87                 return;
  88
  89         volume->current = fsblock;
  90         offset = fsblock * EXT2_BLOCK_SIZE(volume->super);
  91
  92         seek_io(volume->fd, offset);
  93         read_io(volume->fd, volume->buffer, EXT2_BLOCK_SIZE(volume->super));
  94 }
  95
  96 void ext2_get_group_desc(ext2_VOLUME* volume,
  97                    int group_id, struct ext2_group_desc *gdp)
  98 {
  99         unsigned int block, offset;
 100         struct ext2_group_desc *le_gdp;
 101
 102         block = 1 + volume->super->s_first_data_block;
 103         block += group_id / EXT2_DESC_PER_BLOCK(volume->super);
 104         ext2_read_block(volume,  block);
 105
 106         offset = group_id % EXT2_DESC_PER_BLOCK(volume->super);
 107         offset *= sizeof(*gdp);
 108
 109         le_gdp = (struct ext2_group_desc *)(volume->buffer + offset);
 110
 111         gdp->bg_block_bitmap = __le32_to_cpu(le_gdp->bg_block_bitmap);
 112         gdp->bg_inode_bitmap = __le32_to_cpu(le_gdp->bg_inode_bitmap);
 113         gdp->bg_inode_table = __le32_to_cpu(le_gdp->bg_inode_table);
 114         gdp->bg_free_blocks_count = __le16_to_cpu(le_gdp->bg_free_blocks_count);
 115         gdp->bg_free_inodes_count = __le16_to_cpu(le_gdp->bg_free_inodes_count);
 116         gdp->bg_used_dirs_count = __le16_to_cpu(le_gdp->bg_used_dirs_count);
 117 }
 118
 119 int ext2_get_inode(ext2_VOLUME* volume,
 120                     unsigned int ino, struct ext2_inode *inode)
 121 {
 122         struct ext2_group_desc desc;
 123         unsigned int block;
 124         unsigned int group_id;
 125         unsigned int offset;
 126         struct ext2_inode *le_inode;
 127         int i;
 128
 129         ino--;
 130
 131         group_id = ino / EXT2_INODES_PER_GROUP(volume->super);
 132         ext2_get_group_desc(volume, group_id, &desc);
 133
 134         ino %= EXT2_INODES_PER_GROUP(volume->super);
 135
 136         block = desc.bg_inode_table;
 137         block += ino / (EXT2_BLOCK_SIZE(volume->super) /
 138                         EXT2_INODE_SIZE(volume->super));
 139         ext2_read_block(volume, block);
 140
 141         offset = ino % (EXT2_BLOCK_SIZE(volume->super) /
 142                         EXT2_INODE_SIZE(volume->super));
 143         offset *= EXT2_INODE_SIZE(volume->super);
 144
 145         le_inode = (struct ext2_inode *)(volume->buffer + offset);
 146
 147         inode->i_mode = __le16_to_cpu(le_inode->i_mode);
 148         inode->i_uid = __le16_to_cpu(le_inode->i_uid);
 149         inode->i_size = __le32_to_cpu(le_inode->i_size);
 150         inode->i_atime = __le32_to_cpu(le_inode->i_atime);
 151         inode->i_ctime = __le32_to_cpu(le_inode->i_ctime);
 152         inode->i_mtime = __le32_to_cpu(le_inode->i_mtime);
 153         inode->i_dtime = __le32_to_cpu(le_inode->i_dtime);
 154         inode->i_gid = __le16_to_cpu(le_inode->i_gid);
 155         inode->i_links_count = __le16_to_cpu(le_inode->i_links_count);
 156         inode->i_blocks = __le32_to_cpu(le_inode->i_blocks);
 157         inode->i_flags = __le32_to_cpu(le_inode->i_flags);
 158         if (S_ISLNK(inode->i_mode)) {
 159                 memcpy(inode->i_block, le_inode->i_block, EXT2_N_BLOCKS * 4);
 160         } else {
 161                 for (i = 0; i < EXT2_N_BLOCKS; i++)
 162                         inode->i_block[i] = __le32_to_cpu(le_inode->i_block[i]);
 163         }
 164         inode->i_generation = __le32_to_cpu(le_inode->i_generation);
 165         inode->i_file_acl = __le32_to_cpu(le_inode->i_file_acl);
 166         inode->i_dir_acl = __le32_to_cpu(le_inode->i_dir_acl);
 167         inode->i_faddr = __le32_to_cpu(le_inode->i_faddr);
 168         inode->osd2.linux2.l_i_frag = le_inode->osd2.linux2.l_i_frag;
 169         inode->osd2.linux2.l_i_fsize = le_inode->osd2.linux2.l_i_fsize;
 170         inode->osd2.linux2.l_i_uid_high =
 171                         __le16_to_cpu(le_inode->osd2.linux2.l_i_uid_high);
 172         inode->osd2.linux2.l_i_gid_high =
 173                         __le16_to_cpu(le_inode->osd2.linux2.l_i_gid_high);
 174         return 0;
 175 }
 176
 177 unsigned int ext2_get_block_addr(ext2_VOLUME* volume, struct ext2_inode *inode,
 178                                  unsigned int logical)
 179 {
 180         unsigned int physical;
 181         unsigned int addr_per_block;
 182
 183         /* direct */
 184
 185         if (logical < EXT2_NDIR_BLOCKS) {
 186                 physical = inode->i_block[logical];
 187                 return physical;
 188         }
 189
 190         /* indirect */
 191
 192         logical -= EXT2_NDIR_BLOCKS;
 193
 194         addr_per_block = EXT2_ADDR_PER_BLOCK (volume->super);
 195         if (logical < addr_per_block) {
 196                 ext2_read_block(volume, inode->i_block[EXT2_IND_BLOCK]);
 197                 physical = __le32_to_cpu(((unsigned int *)volume->buffer)[logical]);
 198                 return physical;
 199         }
 200
 201         /* double indirect */
 202
 203         logical -=  addr_per_block;
 204
 205         if (logical < addr_per_block * addr_per_block) {
 206                 ext2_read_block(volume, inode->i_block[EXT2_DIND_BLOCK]);
 207                 physical = __le32_to_cpu(((unsigned int *)volume->buffer)
 208                                                 [logical / addr_per_block]);
 209                 ext2_read_block(volume, physical);
 210                 physical = __le32_to_cpu(((unsigned int *)volume->buffer)
 211                                                 [logical % addr_per_block]);
 212                 return physical;
 213         }
 214
 215         /* triple indirect */
 216
 217         logical -= addr_per_block * addr_per_block;
 218         ext2_read_block(volume, inode->i_block[EXT2_DIND_BLOCK]);
 219         physical = __le32_to_cpu(((unsigned int *)volume->buffer)
 220                                 [logical / (addr_per_block * addr_per_block)]);
 221         ext2_read_block(volume, physical);
 222         logical = logical % (addr_per_block * addr_per_block);
 223         physical = __le32_to_cpu(((unsigned int *)volume->buffer)[logical / addr_per_block]);
 224         ext2_read_block(volume, physical);
 225         physical = __le32_to_cpu(((unsigned int *)volume->buffer)[logical % addr_per_block]);
 226         return physical;
 227 }
 228
 229 int ext2_read_data(ext2_VOLUME* volume, struct ext2_inode *inode,
 230                    off_t offset, char *buffer, size_t length)
 231 {
 232         unsigned int logical, physical;
 233         int blocksize = EXT2_BLOCK_SIZE(volume->super);
 234         int shift;
 235         size_t read;
 236
 237         if (offset >= inode->i_size)
 238                 return -1;
 239
 240         if (offset + length >= inode->i_size)
 241                 length = inode->i_size - offset;
 242
 243         read = 0;
 244         logical = offset / blocksize;
 245         shift = offset % blocksize;
 246
 247         if (shift) {
 248                 physical = ext2_get_block_addr(volume, inode, logical);
 249                 ext2_read_block(volume, physical);
 250
 251                 if (length < blocksize - shift) {
 252                         memcpy(buffer, volume->buffer + shift, length);
 253                         return length;
 254                 }
 255                 read += blocksize - shift;
 256                 memcpy(buffer, volume->buffer + shift, read);
 257
 258                 buffer += read;
 259                 length -= read;
 260                 logical++;
 261         }
 262
 263         while (length) {
 264                 physical = ext2_get_block_addr(volume, inode, logical);
 265                 ext2_read_block(volume, physical);
 266
 267                 if (length < blocksize) {
 268                         memcpy(buffer, volume->buffer, length);
 269                         read += length;
 270                         return read;
 271                 }
 272                 memcpy(buffer, volume->buffer, blocksize);
 273
 274                 buffer += blocksize;
 275                 length -= blocksize;
 276                 read += blocksize;
 277                 logical++;
 278         }
 279
 280         return read;
 281 }
 282
 283 off_t ext2_dir_entry(ext2_VOLUME *volume, struct ext2_inode *inode,
 284                      off_t index, struct ext2_dir_entry_2 *entry)
 285 {
 286         int ret;
 287
 288         ret = ext2_read_data(volume, inode, index,
 289                              (char*)entry, sizeof(*entry));
 290         if (ret == -1)
 291                 return -1;
 292
 293         entry->inode = __le32_to_cpu(entry->inode);
 294         entry->rec_len = __le16_to_cpu(entry->rec_len);
 295         return index + entry->rec_len;
 296 }
 297
 298 unsigned int ext2_seek_name(ext2_VOLUME *volume, const char *name)
 299 {
 300         struct ext2_inode inode;
 301         int ret;
 302         unsigned int ino;
 303         off_t index;
 304         struct ext2_dir_entry_2 entry;
 305
 306         ino = EXT2_ROOT_INO;
 307         while(1) {
 308                 while (*name == '\\')
 309                         name++;
 310                 if (!*name)
 311                     break;
 312                 ret = ext2_get_inode(volume, ino, &inode);
 313                 if (ret == -1)
 314                         return 0;
 315                 index = 0;
 316                 while (1) {
 317                         index = ext2_dir_entry(volume, &inode, index, &entry);
 318                         if (index == -1)
 319                                 return 0;
 320                         ret = strncmp(name, entry.name, entry.name_len);
 321                         if (ret == 0  &&
 322                             (name[entry.name_len] == 0 ||
 323                              name[entry.name_len] == '\\')) {
 324                                 ino = entry.inode;
 325                                 break;
 326                         }
 327                 }
 328                 name += entry.name_len;
 329         }
 330
 331         return ino;
 332 }