lwext4/ext4_dir.c

   1 /*
   2  * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
   3  *
   4  *
   5  * HelenOS:
   6  * Copyright (c) 2012 Martin Sucha
   7  * Copyright (c) 2012 Frantisek Princ
   8  * All rights reserved.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  * - Redistributions of source code must retain the above copyright
  15  *   notice, this list of conditions and the following disclaimer.
  16  * - Redistributions in binary form must reproduce the above copyright
  17  *   notice, this list of conditions and the following disclaimer in the
  18  *   documentation and/or other materials provided with the distribution.
  19  * - The name of the author may not be used to endorse or promote products
  20  *   derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 /** @addtogroup lwext4
  35  * @{
  36  */
  37 /**
  38  * @file  ext4_dir.h
  39  * @brief Directory handle procedures.
  40  */
  41
  42 #include "ext4_config.h"
  43 #include "ext4_dir.h"
  44 #include "ext4_dir_idx.h"
  45 #include "ext4_inode.h"
  46 #include "ext4_fs.h"
  47
  48 #include <string.h>
  49
  50 /****************************************************************************/
  51
  52 /**@brief Do some checks before returning iterator.
  53  * @param it Iterator to be checked
  54  * @param block_size Size of data block
  55  * @return Error code
  56  */
  57 static int ext4_dir_iterator_set(struct ext4_directory_iterator *it,
  58                                  uint32_t block_size)
  59 {
  60         it->current = NULL;
  61
  62         uint32_t offset_in_block = it->current_offset % block_size;
  63
  64         /* Ensure proper alignment */
  65         if ((offset_in_block % 4) != 0)
  66                 return EIO;
  67
  68         /* Ensure that the core of the entry does not overflow the block */
  69         if (offset_in_block > block_size - 8)
  70                 return EIO;
  71
  72         struct ext4_directory_entry_ll *entry =
  73             (void *)(it->current_block.data + offset_in_block);
  74
  75         /* Ensure that the whole entry does not overflow the block */
  76         uint16_t length = ext4_dir_entry_ll_get_entry_length(entry);
  77         if (offset_in_block + length > block_size)
  78                 return EIO;
  79
  80         /* Ensure the name length is not too large */
  81         if (ext4_dir_entry_ll_get_name_length(&it->inode_ref->fs->sb, entry) >
  82             length - 8)
  83                 return EIO;
  84
  85         /* Everything OK - "publish" the entry */
  86         it->current = entry;
  87         return EOK;
  88 }
  89
  90 /**@brief Seek to next valid directory entry.
  91  *        Here can be jumped to the next data block.
  92  * @param it  Initialized iterator
  93  * @param pos Position of the next entry
  94  * @return Error code
  95  */
  96 static int ext4_dir_iterator_seek(struct ext4_directory_iterator *it,
  97                                   uint64_t pos)
  98 {
  99         uint64_t size =
 100             ext4_inode_get_size(&it->inode_ref->fs->sb, it->inode_ref->inode);
 101
 102         /* The iterator is not valid until we seek to the desired position */
 103         it->current = NULL;
 104
 105         /* Are we at the end? */
 106         if (pos >= size) {
 107                 if (it->current_block.lb_id) {
 108
 109                         int rc = ext4_block_set(it->inode_ref->fs->bdev,
 110                                                 &it->current_block);
 111                         it->current_block.lb_id = 0;
 112
 113                         if (rc != EOK)
 114                                 return rc;
 115                 }
 116
 117                 it->current_offset = pos;
 118                 return EOK;
 119         }
 120
 121         /* Compute next block address */
 122         uint32_t block_size = ext4_sb_get_block_size(&it->inode_ref->fs->sb);
 123         uint64_t current_block_idx = it->current_offset / block_size;
 124         uint64_t next_block_idx = pos / block_size;
 125
 126         /*
 127          * If we don't have a block or are moving across block boundary,
 128          * we need to get another block
 129          */
 130         if ((it->current_block.lb_id == 0) ||
 131             (current_block_idx != next_block_idx)) {
 132                 if (it->current_block.lb_id) {
 133                         int rc = ext4_block_set(it->inode_ref->fs->bdev,
 134                                                 &it->current_block);
 135                         it->current_block.lb_id = 0;
 136
 137                         if (rc != EOK)
 138                                 return rc;
 139                 }
 140
 141                 uint32_t next_block_phys_idx;
 142                 int rc = ext4_fs_get_inode_data_block_index(
 143                     it->inode_ref, next_block_idx, &next_block_phys_idx);
 144                 if (rc != EOK)
 145                         return rc;
 146
 147                 rc = ext4_block_get(it->inode_ref->fs->bdev, &it->current_block,
 148                                     next_block_phys_idx);
 149                 if (rc != EOK) {
 150                         it->current_block.lb_id = 0;
 151                         return rc;
 152                 }
 153         }
 154
 155         it->current_offset = pos;
 156
 157         return ext4_dir_iterator_set(it, block_size);
 158 }
 159
 160 int ext4_dir_iterator_init(struct ext4_directory_iterator *it,
 161                            struct ext4_inode_ref *inode_ref, uint64_t pos)
 162 {
 163         it->inode_ref = inode_ref;
 164         it->current = 0;
 165         it->current_offset = 0;
 166         it->current_block.lb_id = 0;
 167
 168         return ext4_dir_iterator_seek(it, pos);
 169 }
 170
 171 int ext4_dir_iterator_next(struct ext4_directory_iterator *it)
 172 {
 173         int r = EOK;
 174         uint16_t skip;
 175
 176         while (r == EOK) {
 177                 skip = ext4_dir_entry_ll_get_entry_length(it->current);
 178                 r = ext4_dir_iterator_seek(it, it->current_offset + skip);
 179
 180                 if (!it->current)
 181                         break;
 182                 /*Skip NULL referenced entry*/
 183                 if (ext4_dir_entry_ll_get_inode(it->current) != 0)
 184                         break;
 185         }
 186
 187         return r;
 188 }
 189
 190 int ext4_dir_iterator_fini(struct ext4_directory_iterator *it)
 191 {
 192         it->current = 0;
 193
 194         if (it->current_block.lb_id)
 195                 return ext4_block_set(it->inode_ref->fs->bdev,
 196                                       &it->current_block);
 197
 198         return EOK;
 199 }
 200
 201 void ext4_dir_write_entry(struct ext4_sblock *sb,
 202                           struct ext4_directory_entry_ll *entry,
 203                           uint16_t entry_len, struct ext4_inode_ref *child,
 204                           const char *name, size_t name_len)
 205 {
 206         /* Check maximum entry length */
 207         ext4_assert(entry_len <= ext4_sb_get_block_size(sb));
 208
 209         /* Set basic attributes */
 210         ext4_dir_entry_ll_set_inode(entry, child->index);
 211         ext4_dir_entry_ll_set_entry_length(entry, entry_len);
 212         ext4_dir_entry_ll_set_name_length(sb, entry, name_len);
 213
 214         /* Write name */
 215         memcpy(entry->name, name, name_len);
 216
 217         /* Set type of entry */
 218         if (ext4_inode_is_type(sb, child->inode, EXT4_INODE_MODE_DIRECTORY))
 219                 ext4_dir_entry_ll_set_inode_type(sb, entry,
 220                                                  EXT4_DIRECTORY_FILETYPE_DIR);
 221         else
 222                 ext4_dir_entry_ll_set_inode_type(
 223                     sb, entry, EXT4_DIRECTORY_FILETYPE_REG_FILE);
 224 }
 225
 226 int ext4_dir_add_entry(struct ext4_inode_ref *parent, const char *name,
 227                        uint32_t name_len, struct ext4_inode_ref *child)
 228 {
 229         struct ext4_fs *fs = parent->fs;
 230
 231 #if CONFIG_DIR_INDEX_ENABLE
 232         /* Index adding (if allowed) */
 233         if ((ext4_sb_has_feature_compatible(&fs->sb,
 234                                             EXT4_FEATURE_COMPAT_DIR_INDEX)) &&
 235             (ext4_inode_has_flag(parent->inode, EXT4_INODE_FLAG_INDEX))) {
 236                 int rc = ext4_dir_dx_add_entry(parent, child, name);
 237
 238                 /* Check if index is not corrupted */
 239                 if (rc != EXT4_ERR_BAD_DX_DIR) {
 240                         if (rc != EOK)
 241                                 return rc;
 242
 243                         return EOK;
 244                 }
 245
 246                 /* Needed to clear dir index flag if corrupted */
 247                 ext4_inode_clear_flag(parent->inode, EXT4_INODE_FLAG_INDEX);
 248                 parent->dirty = true;
 249         }
 250 #endif
 251
 252         /* Linear algorithm */
 253         uint32_t iblock = 0;
 254         uint32_t fblock = 0;
 255         uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
 256         uint32_t inode_size = ext4_inode_get_size(&fs->sb, parent->inode);
 257         uint32_t total_blocks = inode_size / block_size;
 258
 259         /* Find block, where is space for new entry and try to add */
 260         bool success = false;
 261         for (iblock = 0; iblock < total_blocks; ++iblock) {
 262                 int rc =
 263                     ext4_fs_get_inode_data_block_index(parent, iblock, &fblock);
 264                 if (rc != EOK)
 265                         return rc;
 266
 267                 struct ext4_block block;
 268                 rc = ext4_block_get(fs->bdev, &block, fblock);
 269                 if (rc != EOK)
 270                         return rc;
 271
 272                 /* If adding is successful, function can finish */
 273                 rc = ext4_dir_try_insert_entry(&fs->sb, &block, child, name,
 274                                                name_len);
 275                 if (rc == EOK)
 276                         success = true;
 277
 278                 rc = ext4_block_set(fs->bdev, &block);
 279                 if (rc != EOK)
 280                         return rc;
 281
 282                 if (success)
 283                         return EOK;
 284         }
 285
 286         /* No free block found - needed to allocate next data block */
 287
 288         iblock = 0;
 289         fblock = 0;
 290         int rc = ext4_fs_append_inode_block(parent, &fblock, &iblock);
 291         if (rc != EOK)
 292                 return rc;
 293
 294         /* Load new block */
 295         struct ext4_block new_block;
 296
 297         rc = ext4_block_get(fs->bdev, &new_block, fblock);
 298         if (rc != EOK)
 299                 return rc;
 300
 301         /* Fill block with zeroes */
 302         memset(new_block.data, 0, block_size);
 303         struct ext4_directory_entry_ll *block_entry = (void *)new_block.data;
 304         ext4_dir_write_entry(&fs->sb, block_entry, block_size, child, name,
 305                              name_len);
 306
 307         /* Save new block */
 308         new_block.dirty = true;
 309         rc = ext4_block_set(fs->bdev, &new_block);
 310
 311         return rc;
 312 }
 313
 314 int ext4_dir_find_entry(struct ext4_directory_search_result *result,
 315                         struct ext4_inode_ref *parent, const char *name,
 316                         uint32_t name_len)
 317 {
 318         struct ext4_sblock *sb = &parent->fs->sb;
 319
 320 #if CONFIG_DIR_INDEX_ENABLE
 321         /* Index search */
 322         if ((ext4_sb_has_feature_compatible(sb,
 323                                             EXT4_FEATURE_COMPAT_DIR_INDEX)) &&
 324             (ext4_inode_has_flag(parent->inode, EXT4_INODE_FLAG_INDEX))) {
 325                 int rc = ext4_dir_dx_find_entry(result, parent, name_len, name);
 326
 327                 /* Check if index is not corrupted */
 328                 if (rc != EXT4_ERR_BAD_DX_DIR) {
 329                         if (rc != EOK)
 330                                 return rc;
 331
 332                         return EOK;
 333                 }
 334
 335                 /* Needed to clear dir index flag if corrupted */
 336                 ext4_inode_clear_flag(parent->inode, EXT4_INODE_FLAG_INDEX);
 337                 parent->dirty = true;
 338         }
 339 #endif
 340
 341         /* Linear algorithm */
 342
 343         uint32_t iblock;
 344         uint32_t fblock;
 345         uint32_t block_size = ext4_sb_get_block_size(sb);
 346         uint32_t inode_size = ext4_inode_get_size(sb, parent->inode);
 347         uint32_t total_blocks = inode_size / block_size;
 348
 349         /* Walk through all data blocks */
 350         for (iblock = 0; iblock < total_blocks; ++iblock) {
 351                 /* Load block address */
 352                 int rc =
 353                     ext4_fs_get_inode_data_block_index(parent, iblock, &fblock);
 354                 if (rc != EOK)
 355                         return rc;
 356
 357                 /* Load data block */
 358                 struct ext4_block block;
 359                 rc = ext4_block_get(parent->fs->bdev, &block, fblock);
 360                 if (rc != EOK)
 361                         return rc;
 362
 363                 /* Try to find entry in block */
 364                 struct ext4_directory_entry_ll *res_entry;
 365                 rc = ext4_dir_find_in_block(&block, sb, name_len, name,
 366                                             &res_entry);
 367                 if (rc == EOK) {
 368                         result->block = block;
 369                         result->dentry = res_entry;
 370                         return EOK;
 371                 }
 372
 373                 /* Entry not found - put block and continue to the next block */
 374
 375                 rc = ext4_block_set(parent->fs->bdev, &block);
 376                 if (rc != EOK)
 377                         return rc;
 378         }
 379
 380         /* Entry was not found */
 381
 382         result->block.lb_id = 0;
 383         result->dentry = NULL;
 384
 385         return ENOENT;
 386 }
 387
 388 int ext4_dir_remove_entry(struct ext4_inode_ref *parent, const char *name,
 389                           uint32_t name_len)
 390 {
 391         /* Check if removing from directory */
 392         if (!ext4_inode_is_type(&parent->fs->sb, parent->inode,
 393                                 EXT4_INODE_MODE_DIRECTORY))
 394                 return ENOTDIR;
 395
 396         /* Try to find entry */
 397         struct ext4_directory_search_result result;
 398         int rc = ext4_dir_find_entry(&result, parent, name, name_len);
 399         if (rc != EOK)
 400                 return rc;
 401
 402         /* Invalidate entry */
 403         ext4_dir_entry_ll_set_inode(result.dentry, 0);
 404
 405         /* Store entry position in block */
 406         uint32_t pos = (uint8_t *)result.dentry - result.block.data;
 407
 408         /*
 409          * If entry is not the first in block, it must be merged
 410          * with previous entry
 411          */
 412         if (pos != 0) {
 413                 uint32_t offset = 0;
 414
 415                 /* Start from the first entry in block */
 416                 struct ext4_directory_entry_ll *tmp_dentry =
 417                     (void *)result.block.data;
 418                 uint16_t tmp_dentry_length =
 419                     ext4_dir_entry_ll_get_entry_length(tmp_dentry);
 420
 421                 /* Find direct predecessor of removed entry */
 422                 while ((offset + tmp_dentry_length) < pos) {
 423                         offset +=
 424                             ext4_dir_entry_ll_get_entry_length(tmp_dentry);
 425                         tmp_dentry = (void *)(result.block.data + offset);
 426                         tmp_dentry_length =
 427                             ext4_dir_entry_ll_get_entry_length(tmp_dentry);
 428                 }
 429
 430                 ext4_assert(tmp_dentry_length + offset == pos);
 431
 432                 /* Add to removed entry length to predecessor's length */
 433                 uint16_t del_entry_length =
 434                     ext4_dir_entry_ll_get_entry_length(result.dentry);
 435                 ext4_dir_entry_ll_set_entry_length(
 436                     tmp_dentry, tmp_dentry_length + del_entry_length);
 437         }
 438
 439         result.block.dirty = true;
 440
 441         return ext4_dir_destroy_result(parent, &result);
 442 }
 443
 444 int ext4_dir_try_insert_entry(struct ext4_sblock *sb,
 445                               struct ext4_block *target_block,
 446                               struct ext4_inode_ref *child, const char *name,
 447                               uint32_t name_len)
 448 {
 449         /* Compute required length entry and align it to 4 bytes */
 450         uint32_t block_size = ext4_sb_get_block_size(sb);
 451         uint16_t required_len =
 452             sizeof(struct ext4_fake_directory_entry) + name_len;
 453
 454         if ((required_len % 4) != 0)
 455                 required_len += 4 - (required_len % 4);
 456
 457         /* Initialize pointers, stop means to upper bound */
 458         struct ext4_directory_entry_ll *dentry = (void *)target_block->data;
 459         struct ext4_directory_entry_ll *stop =
 460             (void *)(target_block->data + block_size);
 461
 462         /*
 463          * Walk through the block and check for invalid entries
 464          * or entries with free space for new entry
 465          */
 466         while (dentry < stop) {
 467                 uint32_t inode = ext4_dir_entry_ll_get_inode(dentry);
 468                 uint16_t rec_len = ext4_dir_entry_ll_get_entry_length(dentry);
 469
 470                 /* If invalid and large enough entry, use it */
 471                 if ((inode == 0) && (rec_len >= required_len)) {
 472                         ext4_dir_write_entry(sb, dentry, rec_len, child, name,
 473                                              name_len);
 474                         target_block->dirty = true;
 475
 476                         return EOK;
 477                 }
 478
 479                 /* Valid entry, try to split it */
 480                 if (inode != 0) {
 481                         uint16_t used_name_len =
 482                             ext4_dir_entry_ll_get_name_length(sb, dentry);
 483
 484                         uint16_t used_space =
 485                             sizeof(struct ext4_fake_directory_entry) +
 486                             used_name_len;
 487
 488                         if ((used_name_len % 4) != 0)
 489                                 used_space += 4 - (used_name_len % 4);
 490
 491                         uint16_t free_space = rec_len - used_space;
 492
 493                         /* There is free space for new entry */
 494                         if (free_space >= required_len) {
 495                                 /* Cut tail of current entry */
 496                                 ext4_dir_entry_ll_set_entry_length(dentry,
 497                                                                    used_space);
 498                                 struct ext4_directory_entry_ll *new_entry =
 499                                     (void *)((uint8_t *)dentry + used_space);
 500                                 ext4_dir_write_entry(sb, new_entry, free_space,
 501                                                      child, name, name_len);
 502
 503                                 target_block->dirty = true;
 504                                 return EOK;
 505                         }
 506                 }
 507
 508                 /* Jump to the next entry */
 509                 dentry = (void *)((uint8_t *)dentry + rec_len);
 510         }
 511
 512         /* No free space found for new entry */
 513         return ENOSPC;
 514 }
 515
 516 int ext4_dir_find_in_block(struct ext4_block *block, struct ext4_sblock *sb,
 517                            size_t name_len, const char *name,
 518                            struct ext4_directory_entry_ll **res_entry)
 519 {
 520         /* Start from the first entry in block */
 521         struct ext4_directory_entry_ll *dentry =
 522             (struct ext4_directory_entry_ll *)block->data;
 523
 524         /* Set upper bound for cycling */
 525         uint8_t *addr_limit = block->data + ext4_sb_get_block_size(sb);
 526
 527         /* Walk through the block and check entries */
 528         while ((uint8_t *)dentry < addr_limit) {
 529                 /* Termination condition */
 530                 if ((uint8_t *)dentry + name_len > addr_limit)
 531                         break;
 532
 533                 /* Valid entry - check it */
 534                 if (ext4_dir_entry_ll_get_inode(dentry) != 0) {
 535                         /* For more efficient compare only lengths firstly*/
 536                         if (ext4_dir_entry_ll_get_name_length(sb, dentry) ==
 537                             name_len) {
 538                                 /* Compare names */
 539                                 if (memcmp((uint8_t *)name, dentry->name,
 540                                            name_len) == 0) {
 541                                         *res_entry = dentry;
 542                                         return EOK;
 543                                 }
 544                         }
 545                 }
 546
 547                 uint16_t dentry_len =
 548                     ext4_dir_entry_ll_get_entry_length(dentry);
 549
 550                 /* Corrupted entry */
 551                 if (dentry_len == 0)
 552                         return EINVAL;
 553
 554                 /* Jump to next entry */
 555                 dentry = (struct ext4_directory_entry_ll *)((uint8_t *)dentry +
 556                                                             dentry_len);
 557         }
 558
 559         /* Entry not found */
 560         return ENOENT;
 561 }
 562
 563 int ext4_dir_destroy_result(struct ext4_inode_ref *parent,
 564                             struct ext4_directory_search_result *result)
 565 {
 566         if (result->block.lb_id)
 567                 return ext4_block_set(parent->fs->bdev, &result->block);
 568
 569         return EOK;
 570 }
 571
 572 /**
 573  * @}
 574  */