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   1 /*
   2  * dentry.c
   3  *
   4  * A dentry (directory entry) contains the metadata for a file.  In the WIM file
   5  * format, the dentries are stored in the "metadata resource" section right
   6  * after the security data.  Each image in the WIM file has its own metadata
   7  * resource with its own security data and dentry tree.  Dentries in different
   8  * images may share file resources by referring to the same lookup table
   9  * entries.
  10  */
  11
  12 /*
  13  *
  14  * Copyright (C) 2010 Carl Thijssen
  15  * Copyright (C) 2012 Eric Biggers
  16  *
  17  * This file is part of wimlib, a library for working with WIM files.
  18  *
  19  * wimlib is free software; you can redistribute it and/or modify it under the
  20  * terms of the GNU Lesser General Public License as published by the Free
  21  * Software Foundation; either version 2.1 of the License, or (at your option)
  22  * any later version.
  23  *
  24  * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
  25  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  26  * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  27  * details.
  28  *
  29  * You should have received a copy of the GNU Lesser General Public License
  30  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  31  */
  32
  33 #include <errno.h>
  34 #include <sys/stat.h>
  35 #include <time.h>
  36 #include <unistd.h>
  37
  38 #include "wimlib_internal.h"
  39 #include "dentry.h"
  40 #include "io.h"
  41 #include "timestamp.h"
  42 #include "lookup_table.h"
  43 #include "sha1.h"
  44
  45 /*
  46  * Returns true if @dentry has the UTF-8 file name @name that has length
  47  * @name_len.
  48  */
  49 static bool dentry_has_name(const struct dentry *dentry, const char *name,
  50                             size_t name_len)
  51 {
  52         if (dentry->file_name_utf8_len != name_len)
  53                 return false;
  54         return memcmp(dentry->file_name_utf8, name, name_len) == 0;
  55 }
  56
  57 /* Real length of a dentry, including the alternate data stream entries, which
  58  * are not included in the dentry->length field... */
  59 u64 dentry_total_length(const struct dentry *dentry)
  60 {
  61         u64 length = (dentry->length + 7) & ~7;
  62         for (u16 i = 0; i < dentry->num_ads; i++)
  63                 length += ads_entry_length(&dentry->ads_entries[i]);
  64         return length;
  65 }
  66
  67 /* Transfers file attributes from a `stat' buffer to a struct dentry. */
  68 void stbuf_to_dentry(const struct stat *stbuf, struct dentry *dentry)
  69 {
  70         if (S_ISLNK(stbuf->st_mode)) {
  71                 dentry->attributes = FILE_ATTRIBUTE_REPARSE_POINT;
  72                 dentry->reparse_tag = WIM_IO_REPARSE_TAG_SYMLINK;
  73         } else if (S_ISDIR(stbuf->st_mode)) {
  74                 dentry->attributes = FILE_ATTRIBUTE_DIRECTORY;
  75         } else {
  76                 dentry->attributes = FILE_ATTRIBUTE_NORMAL;
  77         }
  78         if (sizeof(ino_t) >= 8)
  79                 dentry->hard_link = (u64)stbuf->st_ino;
  80         else
  81                 dentry->hard_link = (u64)stbuf->st_ino |
  82                                    ((u64)stbuf->st_dev << (sizeof(ino_t) * 8));
  83         /* Set timestamps */
  84         dentry->creation_time = timespec_to_wim_timestamp(&stbuf->st_mtim);
  85         dentry->last_write_time = timespec_to_wim_timestamp(&stbuf->st_mtim);
  86         dentry->last_access_time = timespec_to_wim_timestamp(&stbuf->st_atim);
  87 }
  88
  89
  90 /* Makes all timestamp fields for the dentry be the current time. */
  91 void dentry_update_all_timestamps(struct dentry *dentry)
  92 {
  93         u64 now = get_wim_timestamp();
  94         dentry->creation_time    = now;
  95         dentry->last_access_time = now;
  96         dentry->last_write_time  = now;
  97 }
  98
  99 struct ads_entry *dentry_get_ads_entry(struct dentry *dentry,
 100                                        const char *stream_name)
 101 {
 102         size_t stream_name_len = strlen(stream_name);
 103         if (!stream_name)
 104                 return NULL;
 105         for (u16 i = 0; i < dentry->num_ads; i++)
 106                 if (ads_entry_has_name(&dentry->ads_entries[i],
 107                                        stream_name, stream_name_len))
 108                         return &dentry->ads_entries[i];
 109         return NULL;
 110 }
 111
 112 static void ads_entry_init(struct ads_entry *ads_entry)
 113 {
 114         memset(ads_entry, 0, sizeof(struct ads_entry));
 115         INIT_LIST_HEAD(&ads_entry->lte_group_list.list);
 116         ads_entry->lte_group_list.type = STREAM_TYPE_ADS;
 117 }
 118
 119 /* Add an alternate stream entry to a dentry and return a pointer to it, or NULL
 120  * on failure. */
 121 struct ads_entry *dentry_add_ads(struct dentry *dentry, const char *stream_name)
 122 {
 123         u16 num_ads;
 124         struct ads_entry *ads_entries;
 125         struct ads_entry *new_entry;
 126
 127         DEBUG("Add alternate data stream %s:%s",
 128                dentry->file_name_utf8, stream_name);
 129
 130         if (dentry->num_ads == 0xffff)
 131                 return NULL;
 132         num_ads = dentry->num_ads + 1;
 133         ads_entries = REALLOC(dentry->ads_entries,
 134                               num_ads * sizeof(struct ads_entry));
 135         if (!ads_entries)
 136                 return NULL;
 137         if (ads_entries != dentry->ads_entries) {
 138                 /* We moved the ADS entries.  Adjust the stream lists. */
 139                 for (u16 i = 0; i < dentry->num_ads; i++) {
 140                         struct list_head *cur = &ads_entries[i].lte_group_list.list;
 141                         cur->prev->next = cur;
 142                         cur->next->prev = cur;
 143                 }
 144         }
 145
 146         new_entry = &ads_entries[num_ads - 1];
 147         ads_entry_init(new_entry);
 148         if (change_ads_name(new_entry, stream_name) != 0)
 149                 return NULL;
 150         dentry->ads_entries = ads_entries;
 151         dentry->num_ads = num_ads;
 152         return new_entry;
 153 }
 154
 155 void dentry_remove_ads(struct dentry *dentry, struct ads_entry *ads_entry)
 156 {
 157         u16 idx;
 158         u16 following;
 159
 160         wimlib_assert(dentry->num_ads);
 161         idx = ads_entry - dentry->ads_entries;
 162         wimlib_assert(idx < dentry->num_ads);
 163         following = dentry->num_ads - idx - 1;
 164
 165         destroy_ads_entry(ads_entry);
 166         memcpy(ads_entry, ads_entry + 1, following * sizeof(struct ads_entry));
 167
 168         /* We moved the ADS entries.  Adjust the stream lists. */
 169         for (u16 i = 0; i < following; i++) {
 170                 struct list_head *cur = &ads_entry[i].lte_group_list.list;
 171                 cur->prev->next = cur;
 172                 cur->next->prev = cur;
 173         }
 174
 175         dentry->num_ads--;
 176 }
 177
 178 /*
 179  * Calls a function on all directory entries in a directory tree.  It is called
 180  * on a parent before its children.
 181  */
 182 int for_dentry_in_tree(struct dentry *root,
 183                        int (*visitor)(struct dentry*, void*), void *arg)
 184 {
 185         int ret;
 186         struct dentry *child;
 187
 188         ret = visitor(root, arg);
 189
 190         if (ret != 0)
 191                 return ret;
 192
 193         child = root->children;
 194
 195         if (!child)
 196                 return 0;
 197
 198         do {
 199                 ret = for_dentry_in_tree(child, visitor, arg);
 200                 if (ret != 0)
 201                         return ret;
 202                 child = child->next;
 203         } while (child != root->children);
 204         return 0;
 205 }
 206
 207 /*
 208  * Like for_dentry_in_tree(), but the visitor function is always called on a
 209  * dentry's children before on itself.
 210  */
 211 int for_dentry_in_tree_depth(struct dentry *root,
 212                              int (*visitor)(struct dentry*, void*), void *arg)
 213 {
 214         int ret;
 215         struct dentry *child;
 216         struct dentry *next;
 217
 218         child = root->children;
 219         if (child) {
 220                 do {
 221                         next = child->next;
 222                         ret = for_dentry_in_tree_depth(child, visitor, arg);
 223                         if (ret != 0)
 224                                 return ret;
 225                         child = next;
 226                 } while (child != root->children);
 227         }
 228         return visitor(root, arg);
 229 }
 230
 231 /*
 232  * Calculate the full path of @dentry, based on its parent's full path and on
 233  * its UTF-8 file name.
 234  */
 235 int calculate_dentry_full_path(struct dentry *dentry, void *ignore)
 236 {
 237         char *full_path;
 238         u32 full_path_len;
 239         if (dentry_is_root(dentry)) {
 240                 full_path = MALLOC(2);
 241                 if (!full_path)
 242                         goto oom;
 243                 full_path[0] = '/';
 244                 full_path[1] = '\0';
 245                 full_path_len = 1;
 246         } else {
 247                 char *parent_full_path;
 248                 u32 parent_full_path_len;
 249                 const struct dentry *parent = dentry->parent;
 250
 251                 if (dentry_is_root(parent)) {
 252                         parent_full_path = "";
 253                         parent_full_path_len = 0;
 254                 } else {
 255                         parent_full_path = parent->full_path_utf8;
 256                         parent_full_path_len = parent->full_path_utf8_len;
 257                 }
 258
 259                 full_path_len = parent_full_path_len + 1 +
 260                                 dentry->file_name_utf8_len;
 261                 full_path = MALLOC(full_path_len + 1);
 262                 if (!full_path)
 263                         goto oom;
 264
 265                 memcpy(full_path, parent_full_path, parent_full_path_len);
 266                 full_path[parent_full_path_len] = '/';
 267                 memcpy(full_path + parent_full_path_len + 1,
 268                        dentry->file_name_utf8,
 269                        dentry->file_name_utf8_len);
 270                 full_path[full_path_len] = '\0';
 271         }
 272         FREE(dentry->full_path_utf8);
 273         dentry->full_path_utf8 = full_path;
 274         dentry->full_path_utf8_len = full_path_len;
 275         return 0;
 276 oom:
 277         ERROR("Out of memory while calculating dentry full path");
 278         return WIMLIB_ERR_NOMEM;
 279 }
 280
 281 /*
 282  * Recursively calculates the subdir offsets for a directory tree.
 283  *
 284  * @dentry:  The root of the directory tree.
 285  * @subdir_offset_p:  The current subdirectory offset; i.e., the subdirectory
 286  *      offset for @dentry.
 287  */
 288 void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
 289 {
 290         struct dentry *child;
 291
 292         child = dentry->children;
 293         dentry->subdir_offset = *subdir_offset_p;
 294         if (child) {
 295
 296                 /* Advance the subdir offset by the amount of space the children
 297                  * of this dentry take up. */
 298                 do {
 299                         *subdir_offset_p += dentry_total_length(child);
 300                         child = child->next;
 301                 } while (child != dentry->children);
 302
 303                 /* End-of-directory dentry on disk. */
 304                 *subdir_offset_p += 8;
 305
 306                 /* Recursively call calculate_subdir_offsets() on all the
 307                  * children. */
 308                 do {
 309                         calculate_subdir_offsets(child, subdir_offset_p);
 310                         child = child->next;
 311                 } while (child != dentry->children);
 312         } else {
 313                 /* On disk, childless directories have a valid subdir_offset
 314                  * that points to an 8-byte end-of-directory dentry.  Regular
 315                  * files have a subdir_offset of 0. */
 316                 if (dentry_is_directory(dentry))
 317                         *subdir_offset_p += 8;
 318                 else
 319                         dentry->subdir_offset = 0;
 320         }
 321 }
 322
 323
 324 /* Returns the child of @dentry that has the file name @name.
 325  * Returns NULL if no child has the name. */
 326 struct dentry *get_dentry_child_with_name(const struct dentry *dentry,
 327                                                         const char *name)
 328 {
 329         struct dentry *child;
 330         size_t name_len;
 331
 332         child = dentry->children;
 333         if (child) {
 334                 name_len = strlen(name);
 335                 do {
 336                         if (dentry_has_name(child, name, name_len))
 337                                 return child;
 338                         child = child->next;
 339                 } while (child != dentry->children);
 340         }
 341         return NULL;
 342 }
 343
 344 /* Retrieves the dentry that has the UTF-8 @path relative to the dentry
 345  * @cur_dir.  Returns NULL if no dentry having the path is found. */
 346 static struct dentry *get_dentry_relative_path(struct dentry *cur_dir, const char *path)
 347 {
 348         struct dentry *child;
 349         size_t base_len;
 350         const char *new_path;
 351
 352         if (*path == '\0')
 353                 return cur_dir;
 354
 355         child = cur_dir->children;
 356         if (child) {
 357                 new_path = path_next_part(path, &base_len);
 358                 do {
 359                         if (dentry_has_name(child, path, base_len))
 360                                 return get_dentry_relative_path(child, new_path);
 361                         child = child->next;
 362                 } while (child != cur_dir->children);
 363         }
 364         return NULL;
 365 }
 366
 367 /* Returns the dentry corresponding to the UTF-8 @path, or NULL if there is no
 368  * such dentry. */
 369 struct dentry *get_dentry(WIMStruct *w, const char *path)
 370 {
 371         struct dentry *root = wim_root_dentry(w);
 372         while (*path == '/')
 373                 path++;
 374         return get_dentry_relative_path(root, path);
 375 }
 376
 377 /* Returns the parent directory for the @path. */
 378 struct dentry *get_parent_dentry(WIMStruct *w, const char *path)
 379 {
 380         size_t path_len = strlen(path);
 381         char buf[path_len + 1];
 382
 383         memcpy(buf, path, path_len + 1);
 384
 385         to_parent_name(buf, path_len);
 386
 387         return get_dentry(w, buf);
 388 }
 389
 390 /* Prints the full path of a dentry. */
 391 int print_dentry_full_path(struct dentry *dentry, void *ignore)
 392 {
 393         if (dentry->full_path_utf8)
 394                 puts(dentry->full_path_utf8);
 395         return 0;
 396 }
 397
 398 struct file_attr_flag {
 399         u32 flag;
 400         const char *name;
 401 };
 402 struct file_attr_flag file_attr_flags[] = {
 403         {FILE_ATTRIBUTE_READONLY,               "READONLY"},
 404         {FILE_ATTRIBUTE_HIDDEN,         "HIDDEN"},
 405         {FILE_ATTRIBUTE_SYSTEM,         "SYSTEM"},
 406         {FILE_ATTRIBUTE_DIRECTORY,              "DIRECTORY"},
 407         {FILE_ATTRIBUTE_ARCHIVE,                "ARCHIVE"},
 408         {FILE_ATTRIBUTE_DEVICE,         "DEVICE"},
 409         {FILE_ATTRIBUTE_NORMAL,         "NORMAL"},
 410         {FILE_ATTRIBUTE_TEMPORARY,              "TEMPORARY"},
 411         {FILE_ATTRIBUTE_SPARSE_FILE,    "SPARSE_FILE"},
 412         {FILE_ATTRIBUTE_REPARSE_POINT,  "REPARSE_POINT"},
 413         {FILE_ATTRIBUTE_COMPRESSED,             "COMPRESSED"},
 414         {FILE_ATTRIBUTE_OFFLINE,                "OFFLINE"},
 415         {FILE_ATTRIBUTE_NOT_CONTENT_INDEXED,"NOT_CONTENT_INDEXED"},
 416         {FILE_ATTRIBUTE_ENCRYPTED,              "ENCRYPTED"},
 417         {FILE_ATTRIBUTE_VIRTUAL,                "VIRTUAL"},
 418 };
 419
 420 /* Prints a directory entry.  @lookup_table is a pointer to the lookup table, or
 421  * NULL if the resource entry for the dentry is not to be printed. */
 422 int print_dentry(struct dentry *dentry, void *lookup_table)
 423 {
 424         const u8 *hash;
 425         struct lookup_table_entry *lte;
 426
 427         printf("[DENTRY]\n");
 428         printf("Length            = %"PRIu64"\n", dentry->length);
 429         printf("Attributes        = 0x%x\n", dentry->attributes);
 430         for (unsigned i = 0; i < ARRAY_LEN(file_attr_flags); i++)
 431                 if (file_attr_flags[i].flag & dentry->attributes)
 432                         printf("    FILE_ATTRIBUTE_%s is set\n",
 433                                 file_attr_flags[i].name);
 434         printf("Security ID       = %d\n", dentry->security_id);
 435         printf("Subdir offset     = %"PRIu64"\n", dentry->subdir_offset);
 436 #if 0
 437         printf("Unused1           = 0x%"PRIu64"\n", dentry->unused1);
 438         printf("Unused2           = %"PRIu64"\n", dentry->unused2);
 439 #endif
 440 #if 0
 441         printf("Creation Time     = 0x%"PRIx64"\n");
 442         printf("Last Access Time  = 0x%"PRIx64"\n");
 443         printf("Last Write Time   = 0x%"PRIx64"\n");
 444 #endif
 445
 446         time_t creat_time = wim_timestamp_to_unix(dentry->creation_time);
 447         time_t access_time = wim_timestamp_to_unix(dentry->last_access_time);
 448         time_t mod_time = wim_timestamp_to_unix(dentry->last_write_time);
 449         printf("Creation Time     = %s", asctime(localtime(&creat_time)));
 450         printf("Last Access Time  = %s", asctime(localtime(&access_time)));
 451         printf("Last Write Time   = %s", asctime(localtime(&mod_time)));
 452
 453         printf("Reparse Tag       = 0x%"PRIx32"\n", dentry->reparse_tag);
 454         printf("Hard Link Group   = 0x%"PRIx64"\n", dentry->hard_link);
 455         printf("Number of Alternate Data Streams = %hu\n", dentry->num_ads);
 456         printf("Filename          = \"");
 457         print_string(dentry->file_name, dentry->file_name_len);
 458         puts("\"");
 459         printf("Filename Length   = %hu\n", dentry->file_name_len);
 460         printf("Filename (UTF-8)  = \"%s\"\n", dentry->file_name_utf8);
 461         printf("Filename (UTF-8) Length = %hu\n", dentry->file_name_utf8_len);
 462         printf("Short Name        = \"");
 463         print_string(dentry->short_name, dentry->short_name_len);
 464         puts("\"");
 465         printf("Short Name Length = %hu\n", dentry->short_name_len);
 466         printf("Full Path (UTF-8) = \"%s\"\n", dentry->full_path_utf8);
 467         lte = dentry_stream_lte(dentry, 0, lookup_table);
 468         if (lte) {
 469                 print_lookup_table_entry(lte);
 470         } else {
 471                 hash = dentry_stream_hash(dentry, 0);
 472                 if (hash) {
 473                         printf("Hash              = 0x");
 474                         print_hash(hash);
 475                         putchar('\n');
 476                 }
 477         }
 478         for (u16 i = 0; i < dentry->num_ads; i++) {
 479                 printf("[Alternate Stream Entry %u]\n", i);
 480                 printf("Name = \"%s\"\n", dentry->ads_entries[i].stream_name_utf8);
 481                 printf("Name Length (UTF-16) = %u\n",
 482                                 dentry->ads_entries[i].stream_name_len);
 483                 hash = dentry_stream_hash(dentry, i + 1);
 484                 if (hash) {
 485                         printf("Hash              = 0x");
 486                         print_hash(hash);
 487                         putchar('\n');
 488                 }
 489                 print_lookup_table_entry(dentry_stream_lte(dentry, i + 1,
 490                                                            lookup_table));
 491         }
 492         return 0;
 493 }
 494
 495 static inline void dentry_common_init(struct dentry *dentry)
 496 {
 497         memset(dentry, 0, sizeof(struct dentry));
 498         dentry->refcnt = 1;
 499         dentry->security_id = -1;
 500         dentry->ads_entries_status = ADS_ENTRIES_DEFAULT;
 501         dentry->lte_group_list.type = STREAM_TYPE_NORMAL;
 502 }
 503
 504 /*
 505  * Creates an unlinked directory entry.
 506  *
 507  * @name:    The base name of the new dentry.
 508  * @return:  A pointer to the new dentry, or NULL if out of memory.
 509  */
 510 struct dentry *new_dentry(const char *name)
 511 {
 512         struct dentry *dentry;
 513
 514         dentry = MALLOC(sizeof(struct dentry));
 515         if (!dentry)
 516                 goto err;
 517
 518         dentry_common_init(dentry);
 519         if (change_dentry_name(dentry, name) != 0)
 520                 goto err;
 521
 522         dentry_update_all_timestamps(dentry);
 523         dentry->next   = dentry;
 524         dentry->prev   = dentry;
 525         dentry->parent = dentry;
 526         INIT_LIST_HEAD(&dentry->link_group_list);
 527         return dentry;
 528 err:
 529         FREE(dentry);
 530         ERROR("Failed to allocate new dentry");
 531         return NULL;
 532 }
 533
 534 void dentry_free_ads_entries(struct dentry *dentry)
 535 {
 536         for (u16 i = 0; i < dentry->num_ads; i++)
 537                 destroy_ads_entry(&dentry->ads_entries[i]);
 538         FREE(dentry->ads_entries);
 539         dentry->ads_entries = NULL;
 540         dentry->num_ads = 0;
 541 }
 542
 543 static void __destroy_dentry(struct dentry *dentry)
 544 {
 545         FREE(dentry->file_name);
 546         FREE(dentry->file_name_utf8);
 547         FREE(dentry->short_name);
 548         FREE(dentry->full_path_utf8);
 549         FREE(dentry->extracted_file);
 550 }
 551
 552 void free_dentry(struct dentry *dentry)
 553 {
 554         wimlib_assert(dentry);
 555         __destroy_dentry(dentry);
 556         if (dentry->ads_entries_status != ADS_ENTRIES_USER)
 557                 dentry_free_ads_entries(dentry);
 558         FREE(dentry);
 559 }
 560
 561 /* Like free_dentry(), but assigns a new ADS entries owner if this dentry was
 562  * the previous owner, and also deletes the dentry from its link_group_list */
 563 void put_dentry(struct dentry *dentry)
 564 {
 565         if (dentry->ads_entries_status == ADS_ENTRIES_OWNER) {
 566                 struct dentry *new_owner;
 567                 list_for_each_entry(new_owner, &dentry->link_group_list,
 568                                     link_group_list)
 569                 {
 570                         if (new_owner->ads_entries_status == ADS_ENTRIES_USER) {
 571                                 new_owner->ads_entries_status = ADS_ENTRIES_OWNER;
 572                                 break;
 573                         }
 574                 }
 575                 dentry->ads_entries_status = ADS_ENTRIES_USER;
 576         }
 577         struct list_head *next;
 578         list_del(&dentry->link_group_list);
 579         free_dentry(dentry);
 580 }
 581
 582
 583 /* clones a dentry.
 584  *
 585  * Beware:
 586  *      - memory for file names is not cloned
 587  *      - next, prev, and children pointers and not touched
 588  *      - stream entries are not cloned.
 589  */
 590 struct dentry *clone_dentry(struct dentry *old)
 591 {
 592         struct dentry *new = MALLOC(sizeof(struct dentry));
 593         if (!new)
 594                 return NULL;
 595         memcpy(new, old, sizeof(struct dentry));
 596         new->file_name          = NULL;
 597         new->file_name_len      = 0;
 598         new->file_name_utf8     = NULL;
 599         new->file_name_utf8_len = 0;
 600         new->short_name         = NULL;
 601         new->short_name_len     = 0;
 602         return new;
 603 }
 604
 605 /*
 606  * This function is passed as an argument to for_dentry_in_tree_depth() in order
 607  * to free a directory tree.  __args is a pointer to a `struct free_dentry_args'.
 608  */
 609 static int do_free_dentry(struct dentry *dentry, void *__lookup_table)
 610 {
 611         struct lookup_table *lookup_table = __lookup_table;
 612         if (lookup_table) {
 613                 struct lookup_table_entry *lte;
 614                 if (dentry->resolved)
 615                         lte = dentry->lte;
 616                 else
 617                         lte = __lookup_resource(lookup_table, dentry->hash);
 618                 lte_decrement_refcnt(lte, lookup_table);
 619         }
 620
 621         wimlib_assert(dentry->refcnt != 0);
 622         if (--dentry->refcnt == 0)
 623                 free_dentry(dentry);
 624         return 0;
 625 }
 626
 627 /*
 628  * Unlinks and frees a dentry tree.
 629  *
 630  * @root:               The root of the tree.
 631  * @lookup_table:       The lookup table for dentries.  If non-NULL, the
 632  *                      reference counts in the lookup table for the lookup
 633  *                      table entries corresponding to the dentries will be
 634  *                      decremented.
 635  */
 636 void free_dentry_tree(struct dentry *root, struct lookup_table *lookup_table)
 637 {
 638         if (!root || !root->parent)
 639                 return;
 640         for_dentry_in_tree_depth(root, do_free_dentry, lookup_table);
 641 }
 642
 643 int increment_dentry_refcnt(struct dentry *dentry, void *ignore)
 644 {
 645         dentry->refcnt++;
 646         return 0;
 647 }
 648
 649 /*
 650  * Links a dentry into the directory tree.
 651  *
 652  * @dentry: The dentry to link.
 653  * @parent: The dentry that will be the parent of @dentry.
 654  */
 655 void link_dentry(struct dentry *dentry, struct dentry *parent)
 656 {
 657         wimlib_assert(dentry_is_directory(parent));
 658         dentry->parent = parent;
 659         if (parent->children) {
 660                 /* Not an only child; link to siblings. */
 661                 dentry->next = parent->children;
 662                 dentry->prev = parent->children->prev;
 663                 dentry->next->prev = dentry;
 664                 dentry->prev->next = dentry;
 665         } else {
 666                 /* Only child; link to parent. */
 667                 parent->children = dentry;
 668                 dentry->next = dentry;
 669                 dentry->prev = dentry;
 670         }
 671 }
 672
 673
 674 /* Unlink a dentry from the directory tree.
 675  *
 676  * Note: This merely removes it from the in-memory tree structure.  See
 677  * remove_dentry() in mount.c for a function implemented on top of this one that
 678  * frees the dentry and implements reference counting for the lookup table
 679  * entries. */
 680 void unlink_dentry(struct dentry *dentry)
 681 {
 682         if (dentry_is_root(dentry))
 683                 return;
 684         if (dentry_is_only_child(dentry)) {
 685                 dentry->parent->children = NULL;
 686         } else {
 687                 if (dentry_is_first_sibling(dentry))
 688                         dentry->parent->children = dentry->next;
 689                 dentry->next->prev = dentry->prev;
 690                 dentry->prev->next = dentry->next;
 691         }
 692 }
 693
 694
 695 /* Recalculates the length of @dentry based on its file name length and short
 696  * name length.  */
 697 static inline void recalculate_dentry_size(struct dentry *dentry)
 698 {
 699         dentry->length = WIM_DENTRY_DISK_SIZE + dentry->file_name_len +
 700                          2 + dentry->short_name_len;
 701         /* Must be multiple of 8. */
 702         dentry->length = (dentry->length + 7) & ~7;
 703 }
 704
 705 /* Duplicates a UTF-8 name into UTF-8 and UTF-16 strings and returns the strings
 706  * and their lengths in the pointer arguments */
 707 int get_names(char **name_utf16_ret, char **name_utf8_ret,
 708               u16 *name_utf16_len_ret, u16 *name_utf8_len_ret,
 709               const char *name)
 710 {
 711         size_t utf8_len;
 712         size_t utf16_len;
 713         char *name_utf16, *name_utf8;
 714
 715         utf8_len = strlen(name);
 716
 717         name_utf16 = utf8_to_utf16(name, utf8_len, &utf16_len);
 718
 719         if (!name_utf16)
 720                 return WIMLIB_ERR_NOMEM;
 721
 722         name_utf8 = MALLOC(utf8_len + 1);
 723         if (!name_utf8) {
 724                 FREE(name_utf8);
 725                 return WIMLIB_ERR_NOMEM;
 726         }
 727         memcpy(name_utf8, name, utf8_len + 1);
 728         FREE(*name_utf8_ret);
 729         FREE(*name_utf16_ret);
 730         *name_utf8_ret      = name_utf8;
 731         *name_utf16_ret     = name_utf16;
 732         *name_utf8_len_ret  = utf8_len;
 733         *name_utf16_len_ret = utf16_len;
 734         return 0;
 735 }
 736
 737 /* Changes the name of a dentry to @new_name.  Only changes the file_name and
 738  * file_name_utf8 fields; does not change the short_name, short_name_utf8, or
 739  * full_path_utf8 fields.  Also recalculates its length. */
 740 int change_dentry_name(struct dentry *dentry, const char *new_name)
 741 {
 742         int ret;
 743
 744         ret = get_names(&dentry->file_name, &dentry->file_name_utf8,
 745                         &dentry->file_name_len, &dentry->file_name_utf8_len,
 746                          new_name);
 747         if (ret == 0)
 748                 recalculate_dentry_size(dentry);
 749         return ret;
 750 }
 751
 752 int change_ads_name(struct ads_entry *entry, const char *new_name)
 753 {
 754         return get_names(&entry->stream_name, &entry->stream_name_utf8,
 755                          &entry->stream_name_len,
 756                          &entry->stream_name_utf8_len,
 757                          new_name);
 758 }
 759
 760 /* Parameters for calculate_dentry_statistics(). */
 761 struct image_statistics {
 762         struct lookup_table *lookup_table;
 763         u64 *dir_count;
 764         u64 *file_count;
 765         u64 *total_bytes;
 766         u64 *hard_link_bytes;
 767 };
 768
 769 static int calculate_dentry_statistics(struct dentry *dentry, void *arg)
 770 {
 771         struct image_statistics *stats;
 772         struct lookup_table_entry *lte;
 773         u16 i;
 774
 775         stats = arg;
 776
 777         if (dentry_is_directory(dentry) && !dentry_is_root(dentry))
 778                 ++*stats->dir_count;
 779         else
 780                 ++*stats->file_count;
 781
 782         if (dentry->resolved)
 783                 lte = dentry->lte;
 784         else
 785                 lte = __lookup_resource(stats->lookup_table, dentry->hash);
 786         i = 0;
 787         while (1) {
 788                 if (lte) {
 789                         u64 size = lte->resource_entry.original_size;
 790                         *stats->total_bytes += size;
 791                         if (++lte->out_refcnt == 1)
 792                                 *stats->hard_link_bytes += size;
 793                 }
 794                 if (i == dentry->num_ads)
 795                         break;
 796                 lte = __lookup_resource(stats->lookup_table,
 797                                         dentry->ads_entries[i].hash);
 798                 i++;
 799         }
 800
 801         return 0;
 802 }
 803
 804 void calculate_dir_tree_statistics(struct dentry *root, struct lookup_table *table,
 805                                    u64 *dir_count_ret, u64 *file_count_ret,
 806                                    u64 *total_bytes_ret,
 807                                    u64 *hard_link_bytes_ret)
 808 {
 809         struct image_statistics stats;
 810         *dir_count_ret         = 0;
 811         *file_count_ret        = 0;
 812         *total_bytes_ret       = 0;
 813         *hard_link_bytes_ret   = 0;
 814         stats.lookup_table     = table;
 815         stats.dir_count       = dir_count_ret;
 816         stats.file_count      = file_count_ret;
 817         stats.total_bytes     = total_bytes_ret;
 818         stats.hard_link_bytes = hard_link_bytes_ret;
 819         for_lookup_table_entry(table, zero_out_refcnts, NULL);
 820         for_dentry_in_tree(root, calculate_dentry_statistics, &stats);
 821 }
 822
 823 static int read_ads_entries(const u8 *p, struct dentry *dentry,
 824                             u64 remaining_size)
 825 {
 826         u16 num_ads = dentry->num_ads;
 827         struct ads_entry *ads_entries = CALLOC(num_ads, sizeof(struct ads_entry));
 828         int ret;
 829         if (!ads_entries) {
 830                 ERROR("Could not allocate memory for %"PRIu16" "
 831                       "alternate data stream entries", num_ads);
 832                 return WIMLIB_ERR_NOMEM;
 833         }
 834         DEBUG2("Reading %"PRIu16" alternate data streams "
 835                "(remaining size = %"PRIu64")", num_ads, remaining_size);
 836
 837         for (u16 i = 0; i < num_ads; i++) {
 838                 struct ads_entry *cur_entry = &ads_entries[i];
 839                 u64 length;
 840                 size_t utf8_len;
 841                 const char *p_save = p;
 842                 /* Read the base stream entry, excluding the stream name. */
 843                 if (remaining_size < WIM_ADS_ENTRY_DISK_SIZE) {
 844                         ERROR("Stream entries go past end of metadata resource");
 845                         ERROR("(remaining_size = %"PRIu64")", remaining_size);
 846                         ret = WIMLIB_ERR_INVALID_DENTRY;
 847                         goto out_free_ads_entries;
 848                 }
 849                 remaining_size -= WIM_ADS_ENTRY_DISK_SIZE;
 850
 851                 p = get_u64(p, &length); /* ADS entry length */
 852
 853                 DEBUG2("ADS length = %"PRIu64, length);
 854
 855                 p += 8; /* Unused */
 856                 p = get_bytes(p, SHA1_HASH_SIZE, (u8*)cur_entry->hash);
 857                 p = get_u16(p, &cur_entry->stream_name_len);
 858
 859                 DEBUG2("Stream name length = %u", cur_entry->stream_name_len);
 860
 861                 cur_entry->stream_name = NULL;
 862                 cur_entry->stream_name_utf8 = NULL;
 863
 864                 if (remaining_size < cur_entry->stream_name_len + 2) {
 865                         ERROR("Stream entries go past end of metadata resource");
 866                         ERROR("(remaining_size = %"PRIu64" bytes, stream_name_len "
 867                               "= %"PRIu16" bytes", remaining_size,
 868                               cur_entry->stream_name_len);
 869                         ret = WIMLIB_ERR_INVALID_DENTRY;
 870                         goto out_free_ads_entries;
 871                 }
 872                 remaining_size -= cur_entry->stream_name_len + 2;
 873
 874                 cur_entry->stream_name = MALLOC(cur_entry->stream_name_len);
 875                 if (!cur_entry->stream_name) {
 876                         ret = WIMLIB_ERR_NOMEM;
 877                         goto out_free_ads_entries;
 878                 }
 879                 get_bytes(p, cur_entry->stream_name_len,
 880                           (u8*)cur_entry->stream_name);
 881                 cur_entry->stream_name_utf8 = utf16_to_utf8(cur_entry->stream_name,
 882                                                             cur_entry->stream_name_len,
 883                                                             &utf8_len);
 884                 cur_entry->stream_name_utf8_len = utf8_len;
 885
 886                 if (!cur_entry->stream_name_utf8) {
 887                         ret = WIMLIB_ERR_NOMEM;
 888                         goto out_free_ads_entries;
 889                 }
 890                 p = p_save + ads_entry_length(cur_entry);
 891         }
 892         dentry->ads_entries = ads_entries;
 893         return 0;
 894 out_free_ads_entries:
 895         for (u16 i = 0; i < num_ads; i++) {
 896                 FREE(ads_entries[i].stream_name);
 897                 FREE(ads_entries[i].stream_name_utf8);
 898         }
 899         FREE(ads_entries);
 900         return ret;
 901 }
 902
 903 /*
 904  * Reads a directory entry from the metadata resource.
 905  */
 906 int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
 907                 u64 offset, struct dentry *dentry)
 908 {
 909         const u8 *p;
 910         u64 calculated_size;
 911         char *file_name;
 912         char *file_name_utf8;
 913         char *short_name;
 914         u16 short_name_len;
 915         u16 file_name_len;
 916         size_t file_name_utf8_len;
 917         int ret;
 918
 919         dentry_common_init(dentry);
 920
 921         /*Make sure the dentry really fits into the metadata resource.*/
 922         if (offset + 8 > metadata_resource_len) {
 923                 ERROR("Directory entry starting at %"PRIu64" ends past the "
 924                       "end of the metadata resource (size %"PRIu64")",
 925                       offset, metadata_resource_len);
 926                 return WIMLIB_ERR_INVALID_DENTRY;
 927         }
 928
 929         /* Before reading the whole entry, we need to read just the length.
 930          * This is because an entry of length 8 (that is, just the length field)
 931          * terminates the list of sibling directory entries. */
 932
 933         p = get_u64(&metadata_resource[offset], &dentry->length);
 934
 935         /* A zero length field (really a length of 8, since that's how big the
 936          * directory entry is...) indicates that this is the end of directory
 937          * dentry.  We do not read it into memory as an actual dentry, so just
 938          * return true in that case. */
 939         if (dentry->length == 0)
 940                 return 0;
 941
 942         if (offset + dentry->length >= metadata_resource_len) {
 943                 ERROR("Directory entry at offset %"PRIu64" and with size "
 944                       "%"PRIu64" ends past the end of the metadata resource "
 945                       "(size %"PRIu64")",
 946                       offset, dentry->length, metadata_resource_len);
 947                 return WIMLIB_ERR_INVALID_DENTRY;
 948         }
 949
 950         /* If it is a recognized length, read the rest of the directory entry.
 951          * Note: The root directory entry has no name, and its length does not
 952          * include the short name length field.  */
 953         if (dentry->length < WIM_DENTRY_DISK_SIZE) {
 954                 ERROR("Directory entry has invalid length of %"PRIu64" bytes",
 955                       dentry->length);
 956                 return WIMLIB_ERR_INVALID_DENTRY;
 957         }
 958
 959         p = get_u32(p, &dentry->attributes);
 960         p = get_u32(p, (u32*)&dentry->security_id);
 961         p = get_u64(p, &dentry->subdir_offset);
 962
 963         /* 2 unused fields */
 964         p += 2 * sizeof(u64);
 965         /*p = get_u64(p, &dentry->unused1);*/
 966         /*p = get_u64(p, &dentry->unused2);*/
 967
 968         p = get_u64(p, &dentry->creation_time);
 969         p = get_u64(p, &dentry->last_access_time);
 970         p = get_u64(p, &dentry->last_write_time);
 971
 972         p = get_bytes(p, SHA1_HASH_SIZE, dentry->hash);
 973
 974         /*
 975          * I don't know what's going on here.  It seems like M$ screwed up the
 976          * reparse points, then put the fields in the same place and didn't
 977          * document it.  The WIM_HDR_FLAG_RP_FIX flag in the WIM header might
 978          * have something to do with this, but it's not documented.
 979          */
 980         if (dentry->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
 981                 /* ??? */
 982                 p += 4;
 983                 p = get_u32(p, &dentry->reparse_tag);
 984                 p += 4;
 985         } else {
 986                 p = get_u32(p, &dentry->reparse_tag);
 987                 p = get_u64(p, &dentry->hard_link);
 988         }
 989
 990         /* By the way, the reparse_reserved field does not actually exist (at
 991          * least when the file is not a reparse point) */
 992
 993
 994         p = get_u16(p, &dentry->num_ads);
 995
 996         p = get_u16(p, &short_name_len);
 997         p = get_u16(p, &file_name_len);
 998
 999         calculated_size = WIM_DENTRY_DISK_SIZE + file_name_len + 2 +
1000                           short_name_len;
1001
1002         if (dentry->length < calculated_size) {
1003                 ERROR("Unexpected end of directory entry! (Expected "
1004                       "%"PRIu64" bytes, got %"PRIu64" bytes. "
1005                       "short_name_len = %hu, file_name_len = %hu)",
1006                       calculated_size, dentry->length,
1007                       short_name_len, file_name_len);
1008                 return WIMLIB_ERR_INVALID_DENTRY;
1009         }
1010
1011         /* Read the filename. */
1012         file_name = MALLOC(file_name_len);
1013         if (!file_name) {
1014                 ERROR("Failed to allocate %hu bytes for dentry file name",
1015                       file_name_len);
1016                 return WIMLIB_ERR_NOMEM;
1017         }
1018         p = get_bytes(p, file_name_len, file_name);
1019
1020         /* Convert filename to UTF-8. */
1021         file_name_utf8 = utf16_to_utf8(file_name, file_name_len,
1022                                        &file_name_utf8_len);
1023
1024         if (!file_name_utf8) {
1025                 ERROR("Failed to allocate memory to convert UTF-16 "
1026                       "filename (%hu bytes) to UTF-8", file_name_len);
1027                 ret = WIMLIB_ERR_NOMEM;
1028                 goto out_free_file_name;
1029         }
1030
1031         /* Undocumented padding between file name and short name.  This probably
1032          * is supposed to be a terminating null character. */
1033         p += 2;
1034
1035         /* Read the short filename. */
1036         short_name = MALLOC(short_name_len);
1037         if (!short_name) {
1038                 ERROR("Failed to allocate %hu bytes for short filename",
1039                       short_name_len);
1040                 ret = WIMLIB_ERR_NOMEM;
1041                 goto out_free_file_name_utf8;
1042         }
1043
1044         p = get_bytes(p, short_name_len, short_name);
1045
1046         /* Some directory entries inexplicibly have a little over 70 bytes of
1047          * extra data.  The exact amount of data seems to be 72 bytes, but it is
1048          * aligned on the next 8-byte boundary.  Here's an example of the
1049          * aligned data:
1050          *
1051          * 01000000 40000000 6c786bba c58ede11 b0bb0026 1870892a b6adb76f
1052          * e63a3e46 8fca8653 0d2effa1 6c786bba c58ede11 b0bb0026 1870892a
1053          * 00000000 00000000 00000000 00000000
1054          *
1055          * Here's one interpretation of how the data is laid out.
1056          *
1057          * struct unknown {
1058          *      u32 field1; (always 0x00000001)
1059          *      u32 field2; (always 0x40000000)
1060          *      u8  data[48]; (???)
1061          *      u64 reserved1; (always 0)
1062          *      u64 reserved2; (always 0)
1063          * };*/
1064 #if 0
1065         if (dentry->length - calculated_size >= WIM_ADS_ENTRY_DISK_SIZE) {
1066                 printf("%s: %lu / %lu (", file_name_utf8,
1067                                 calculated_size, dentry->length);
1068                 print_string(p + WIM_ADS_ENTRY_DISK_SIZE, dentry->length - calculated_size - WIM_ADS_ENTRY_DISK_SIZE);
1069                 puts(")");
1070                 print_byte_field(p, dentry->length - calculated_size);
1071                 putchar('\n');
1072         }
1073 #endif
1074
1075         if (dentry->num_ads != 0) {
1076                 calculated_size = (calculated_size + 7) & ~7;
1077                 if (calculated_size > metadata_resource_len - offset) {
1078                         ERROR("Not enough space in metadata resource for "
1079                               "alternate stream entries");
1080                         ret = WIMLIB_ERR_INVALID_DENTRY;
1081                         goto out_free_short_name;
1082                 }
1083                 ret = read_ads_entries(&metadata_resource[offset + calculated_size],
1084                                        dentry,
1085                                        metadata_resource_len - offset - calculated_size);
1086                 if (ret != 0)
1087                         goto out_free_short_name;
1088         }
1089
1090         dentry->file_name          = file_name;
1091         dentry->file_name_utf8     = file_name_utf8;
1092         dentry->short_name         = short_name;
1093         dentry->file_name_len      = file_name_len;
1094         dentry->file_name_utf8_len = file_name_utf8_len;
1095         dentry->short_name_len     = short_name_len;
1096         return 0;
1097 out_free_short_name:
1098         FREE(short_name);
1099 out_free_file_name_utf8:
1100         FREE(file_name_utf8);
1101 out_free_file_name:
1102         FREE(file_name);
1103         return ret;
1104 }
1105
1106 /*
1107  * Writes a dentry to an output buffer.
1108  *
1109  * @dentry:  The dentry structure.
1110  * @p:       The memory location to write the data to.
1111  * @return:  Pointer to the byte after the last byte we wrote as part of the
1112  *              dentry.
1113  */
1114 static u8 *write_dentry(const struct dentry *dentry, u8 *p)
1115 {
1116         u8 *orig_p = p;
1117         unsigned padding;
1118         const u8 *hash;
1119
1120         p = put_u64(p, dentry->length);
1121         p = put_u32(p, dentry->attributes);
1122         p = put_u32(p, dentry->security_id);
1123         p = put_u64(p, dentry->subdir_offset);
1124         p = put_u64(p, 0); /* unused1 */
1125         p = put_u64(p, 0); /* unused2 */
1126         p = put_u64(p, dentry->creation_time);
1127         p = put_u64(p, dentry->last_access_time);
1128         p = put_u64(p, dentry->last_write_time);
1129         if (dentry->resolved && dentry->lte)
1130                 hash = dentry->lte->hash;
1131         else
1132                 hash = dentry->hash;
1133         p = put_bytes(p, SHA1_HASH_SIZE, hash);
1134         if (dentry->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
1135                 p = put_zeroes(p, 4);
1136                 p = put_u32(p, dentry->reparse_tag);
1137                 p = put_zeroes(p, 4);
1138         } else {
1139                 u64 hard_link;
1140                 p = put_u32(p, dentry->reparse_tag);
1141                 if (dentry->link_group_list.next == &dentry->link_group_list)
1142                         hard_link = 0;
1143                 else
1144                         hard_link = dentry->hard_link;
1145                 p = put_u64(p, hard_link);
1146         }
1147         p = put_u16(p, dentry->num_ads);
1148         p = put_u16(p, dentry->short_name_len);
1149         p = put_u16(p, dentry->file_name_len);
1150         p = put_bytes(p, dentry->file_name_len, (u8*)dentry->file_name);
1151         p = put_u16(p, 0); /* filename padding, 2 bytes. */
1152         p = put_bytes(p, dentry->short_name_len, (u8*)dentry->short_name);
1153
1154         wimlib_assert(p - orig_p <= dentry->length);
1155         if (p - orig_p < dentry->length)
1156                 p = put_zeroes(p, dentry->length - (p - orig_p));
1157
1158         p = put_zeroes(p, (8 - dentry->length % 8) % 8);
1159
1160         for (u16 i = 0; i < dentry->num_ads; i++) {
1161                 p = put_u64(p, ads_entry_length(&dentry->ads_entries[i]));
1162                 p = put_u64(p, 0); /* Unused */
1163                 if (dentry->resolved && dentry->ads_entries[i].lte)
1164                         hash = dentry->ads_entries[i].lte->hash;
1165                 else
1166                         hash = dentry->ads_entries[i].hash;
1167                 p = put_bytes(p, SHA1_HASH_SIZE, hash);
1168                 p = put_u16(p, dentry->ads_entries[i].stream_name_len);
1169                 p = put_bytes(p, dentry->ads_entries[i].stream_name_len,
1170                                  (u8*)dentry->ads_entries[i].stream_name);
1171                 p = put_u16(p, 0);
1172                 p = put_zeroes(p, (8 - (p - orig_p) % 8) % 8);
1173         }
1174         return p;
1175 }
1176
1177 /* Recursive function that writes a dentry tree rooted at @tree, not including
1178  * @tree itself, which has already been written, except in the case of the root
1179  * dentry, which is written right away, along with an end-of-directory entry. */
1180 u8 *write_dentry_tree(const struct dentry *tree, u8 *p)
1181 {
1182         const struct dentry *child;
1183
1184         if (dentry_is_root(tree)) {
1185                 p = write_dentry(tree, p);
1186
1187                 /* write end of directory entry */
1188                 p = put_u64(p, 0);
1189         } else {
1190                 /* Nothing to do for non-directories */
1191                 if (!dentry_is_directory(tree))
1192                         return p;
1193         }
1194
1195         /* Write child dentries and end-of-directory entry. */
1196         child = tree->children;
1197         if (child) {
1198                 do {
1199                         p = write_dentry(child, p);
1200                         child = child->next;
1201                 } while (child != tree->children);
1202         }
1203
1204         /* write end of directory entry */
1205         p = put_u64(p, 0);
1206
1207         /* Recurse on children. */
1208         if (child) {
1209                 do {
1210                         p = write_dentry_tree(child, p);
1211                         child = child->next;
1212                 } while (child != tree->children);
1213         }
1214         return p;
1215 }
1216
1217 /* Reads the children of a dentry, and all their children, ..., etc. from the
1218  * metadata resource and into the dentry tree.
1219  *
1220  * @metadata_resource:  An array that contains the uncompressed metadata
1221  *                      resource for the WIM file.
1222  * @metadata_resource_len:      The length of @metadata_resource.
1223  * @dentry:     A pointer to a struct dentry that is the root of the directory
1224  *              tree and has already been read from the metadata resource.  It
1225  *              does not need to be the real root because this procedure is
1226  *              called recursively.
1227  *
1228  * @return:     Zero on success, nonzero on failure.
1229  */
1230 int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
1231                      struct dentry *dentry)
1232 {
1233         u64 cur_offset = dentry->subdir_offset;
1234         struct dentry *prev_child = NULL;
1235         struct dentry *first_child = NULL;
1236         struct dentry *child;
1237         struct dentry cur_child;
1238         int ret;
1239
1240         /* If @dentry is a regular file, nothing more needs to be done for this
1241          * branch. */
1242         if (cur_offset == 0)
1243                 return 0;
1244
1245         /* Find and read all the children of @dentry. */
1246         while (1) {
1247
1248                 /* Read next child of @dentry into @cur_child. */
1249                 ret = read_dentry(metadata_resource, metadata_resource_len,
1250                                   cur_offset, &cur_child);
1251                 if (ret != 0)
1252                         break;
1253
1254                 /* Check for end of directory. */
1255                 if (cur_child.length == 0) {
1256                         ret = 0;
1257                         break;
1258                 }
1259
1260                 /* Not end of directory.  Allocate this child permanently and
1261                  * link it to the parent and previous child. */
1262                 child = MALLOC(sizeof(struct dentry));
1263                 if (!child) {
1264                         ERROR("Failed to allocate %zu bytes for new dentry",
1265                               sizeof(struct dentry));
1266                         ret = WIMLIB_ERR_NOMEM;
1267                         break;
1268                 }
1269                 memcpy(child, &cur_child, sizeof(struct dentry));
1270
1271                 if (prev_child) {
1272                         prev_child->next = child;
1273                         child->prev = prev_child;
1274                 } else {
1275                         first_child = child;
1276                 }
1277
1278                 child->parent = dentry;
1279                 prev_child = child;
1280
1281                 /* If there are children of this child, call this procedure
1282                  * recursively. */
1283                 if (child->subdir_offset != 0) {
1284                         ret = read_dentry_tree(metadata_resource,
1285                                                metadata_resource_len, child);
1286                         if (ret != 0)
1287                                 break;
1288                 }
1289
1290                 /* Advance to the offset of the next child. */
1291                 cur_offset += dentry_total_length(child);
1292         }
1293
1294         /* Link last child to first one, and set parent's
1295          * children pointer to the first child.  */
1296         if (prev_child) {
1297                 prev_child->next = first_child;
1298                 first_child->prev = prev_child;
1299         }
1300         dentry->children = first_child;
1301         return ret;
1302 }