wimlib.net Git - wimlib/blob - src/dentry.c

   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;
 103         if (!stream_name)
 104                 return NULL;
 105         if (dentry->num_ads) {
 106                 u16 i = 0;
 107                 stream_name_len = strlen(stream_name);
 108                 do {
 109                         if (ads_entry_has_name(&dentry->ads_entries[i],
 110                                                stream_name, stream_name_len))
 111                                 return &dentry->ads_entries[i];
 112                 } while (++i != dentry->num_ads);
 113         }
 114         return NULL;
 115 }
 116
 117 static void ads_entry_init(struct ads_entry *ads_entry)
 118 {
 119         memset(ads_entry, 0, sizeof(struct ads_entry));
 120         INIT_LIST_HEAD(&ads_entry->lte_group_list.list);
 121         ads_entry->lte_group_list.type = STREAM_TYPE_ADS;
 122 }
 123
 124 /* Add an alternate stream entry to a dentry and return a pointer to it, or NULL
 125  * on failure. */
 126 struct ads_entry *dentry_add_ads(struct dentry *dentry, const char *stream_name)
 127 {
 128         u16 num_ads;
 129         struct ads_entry *ads_entries;
 130         struct ads_entry *new_entry;
 131
 132         DEBUG("Add alternate data stream %s:%s",
 133                dentry->file_name_utf8, stream_name);
 134
 135         if (dentry->num_ads == 0xffff)
 136                 return NULL;
 137         num_ads = dentry->num_ads + 1;
 138         ads_entries = REALLOC(dentry->ads_entries,
 139                               num_ads * sizeof(struct ads_entry));
 140         if (!ads_entries)
 141                 return NULL;
 142         if (ads_entries != dentry->ads_entries) {
 143                 /* We moved the ADS entries.  Adjust the stream lists. */
 144                 for (u16 i = 0; i < dentry->num_ads; i++) {
 145                         struct list_head *cur = &ads_entries[i].lte_group_list.list;
 146                         cur->prev->next = cur;
 147                         cur->next->prev = cur;
 148                 }
 149         }
 150
 151         new_entry = &ads_entries[num_ads - 1];
 152         ads_entry_init(new_entry);
 153         if (change_ads_name(new_entry, stream_name) != 0)
 154                 return NULL;
 155         dentry->ads_entries = ads_entries;
 156         dentry->num_ads = num_ads;
 157         return new_entry;
 158 }
 159
 160 void dentry_remove_ads(struct dentry *dentry, struct ads_entry *ads_entry)
 161 {
 162         u16 idx;
 163         u16 following;
 164
 165         wimlib_assert(dentry->num_ads);
 166         idx = ads_entry - dentry->ads_entries;
 167         wimlib_assert(idx < dentry->num_ads);
 168         following = dentry->num_ads - idx - 1;
 169
 170         destroy_ads_entry(ads_entry);
 171         memcpy(ads_entry, ads_entry + 1, following * sizeof(struct ads_entry));
 172
 173         /* We moved the ADS entries.  Adjust the stream lists. */
 174         for (u16 i = 0; i < following; i++) {
 175                 struct list_head *cur = &ads_entry[i].lte_group_list.list;
 176                 cur->prev->next = cur;
 177                 cur->next->prev = cur;
 178         }
 179
 180         dentry->num_ads--;
 181 }
 182
 183 /*
 184  * Calls a function on all directory entries in a directory tree.  It is called
 185  * on a parent before its children.
 186  */
 187 int for_dentry_in_tree(struct dentry *root,
 188                        int (*visitor)(struct dentry*, void*), void *arg)
 189 {
 190         int ret;
 191         struct dentry *child;
 192
 193         ret = visitor(root, arg);
 194
 195         if (ret != 0)
 196                 return ret;
 197
 198         child = root->children;
 199
 200         if (!child)
 201                 return 0;
 202
 203         do {
 204                 ret = for_dentry_in_tree(child, visitor, arg);
 205                 if (ret != 0)
 206                         return ret;
 207                 child = child->next;
 208         } while (child != root->children);
 209         return 0;
 210 }
 211
 212 /*
 213  * Like for_dentry_in_tree(), but the visitor function is always called on a
 214  * dentry's children before on itself.
 215  */
 216 int for_dentry_in_tree_depth(struct dentry *root,
 217                              int (*visitor)(struct dentry*, void*), void *arg)
 218 {
 219         int ret;
 220         struct dentry *child;
 221         struct dentry *next;
 222
 223         child = root->children;
 224         if (child) {
 225                 do {
 226                         next = child->next;
 227                         ret = for_dentry_in_tree_depth(child, visitor, arg);
 228                         if (ret != 0)
 229                                 return ret;
 230                         child = next;
 231                 } while (child != root->children);
 232         }
 233         return visitor(root, arg);
 234 }
 235
 236 /*
 237  * Calculate the full path of @dentry, based on its parent's full path and on
 238  * its UTF-8 file name.
 239  */
 240 int calculate_dentry_full_path(struct dentry *dentry, void *ignore)
 241 {
 242         char *full_path;
 243         u32 full_path_len;
 244         if (dentry_is_root(dentry)) {
 245                 full_path = MALLOC(2);
 246                 if (!full_path)
 247                         goto oom;
 248                 full_path[0] = '/';
 249                 full_path[1] = '\0';
 250                 full_path_len = 1;
 251         } else {
 252                 char *parent_full_path;
 253                 u32 parent_full_path_len;
 254                 const struct dentry *parent = dentry->parent;
 255
 256                 if (dentry_is_root(parent)) {
 257                         parent_full_path = "";
 258                         parent_full_path_len = 0;
 259                 } else {
 260                         parent_full_path = parent->full_path_utf8;
 261                         parent_full_path_len = parent->full_path_utf8_len;
 262                 }
 263
 264                 full_path_len = parent_full_path_len + 1 +
 265                                 dentry->file_name_utf8_len;
 266                 full_path = MALLOC(full_path_len + 1);
 267                 if (!full_path)
 268                         goto oom;
 269
 270                 memcpy(full_path, parent_full_path, parent_full_path_len);
 271                 full_path[parent_full_path_len] = '/';
 272                 memcpy(full_path + parent_full_path_len + 1,
 273                        dentry->file_name_utf8,
 274                        dentry->file_name_utf8_len);
 275                 full_path[full_path_len] = '\0';
 276         }
 277         FREE(dentry->full_path_utf8);
 278         dentry->full_path_utf8 = full_path;
 279         dentry->full_path_utf8_len = full_path_len;
 280         return 0;
 281 oom:
 282         ERROR("Out of memory while calculating dentry full path");
 283         return WIMLIB_ERR_NOMEM;
 284 }
 285
 286 /*
 287  * Recursively calculates the subdir offsets for a directory tree.
 288  *
 289  * @dentry:  The root of the directory tree.
 290  * @subdir_offset_p:  The current subdirectory offset; i.e., the subdirectory
 291  *      offset for @dentry.
 292  */
 293 void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
 294 {
 295         struct dentry *child;
 296
 297         child = dentry->children;
 298         dentry->subdir_offset = *subdir_offset_p;
 299         if (child) {
 300
 301                 /* Advance the subdir offset by the amount of space the children
 302                  * of this dentry take up. */
 303                 do {
 304                         *subdir_offset_p += dentry_total_length(child);
 305                         child = child->next;
 306                 } while (child != dentry->children);
 307
 308                 /* End-of-directory dentry on disk. */
 309                 *subdir_offset_p += 8;
 310
 311                 /* Recursively call calculate_subdir_offsets() on all the
 312                  * children. */
 313                 do {
 314                         calculate_subdir_offsets(child, subdir_offset_p);
 315                         child = child->next;
 316                 } while (child != dentry->children);
 317         } else {
 318                 /* On disk, childless directories have a valid subdir_offset
 319                  * that points to an 8-byte end-of-directory dentry.  Regular
 320                  * files have a subdir_offset of 0. */
 321                 if (dentry_is_directory(dentry))
 322                         *subdir_offset_p += 8;
 323                 else
 324                         dentry->subdir_offset = 0;
 325         }
 326 }
 327
 328
 329 /* Returns the child of @dentry that has the file name @name.
 330  * Returns NULL if no child has the name. */
 331 struct dentry *get_dentry_child_with_name(const struct dentry *dentry,
 332                                                         const char *name)
 333 {
 334         struct dentry *child;
 335         size_t name_len;
 336
 337         child = dentry->children;
 338         if (child) {
 339                 name_len = strlen(name);
 340                 do {
 341                         if (dentry_has_name(child, name, name_len))
 342                                 return child;
 343                         child = child->next;
 344                 } while (child != dentry->children);
 345         }
 346         return NULL;
 347 }
 348
 349 /* Retrieves the dentry that has the UTF-8 @path relative to the dentry
 350  * @cur_dir.  Returns NULL if no dentry having the path is found. */
 351 static struct dentry *get_dentry_relative_path(struct dentry *cur_dir, const char *path)
 352 {
 353         struct dentry *child;
 354         size_t base_len;
 355         const char *new_path;
 356
 357         if (*path == '\0')
 358                 return cur_dir;
 359
 360         child = cur_dir->children;
 361         if (child) {
 362                 new_path = path_next_part(path, &base_len);
 363                 do {
 364                         if (dentry_has_name(child, path, base_len))
 365                                 return get_dentry_relative_path(child, new_path);
 366                         child = child->next;
 367                 } while (child != cur_dir->children);
 368         }
 369         return NULL;
 370 }
 371
 372 /* Returns the dentry corresponding to the UTF-8 @path, or NULL if there is no
 373  * such dentry. */
 374 struct dentry *get_dentry(WIMStruct *w, const char *path)
 375 {
 376         struct dentry *root = wim_root_dentry(w);
 377         while (*path == '/')
 378                 path++;
 379         return get_dentry_relative_path(root, path);
 380 }
 381
 382 /* Returns the parent directory for the @path. */
 383 struct dentry *get_parent_dentry(WIMStruct *w, const char *path)
 384 {
 385         size_t path_len = strlen(path);
 386         char buf[path_len + 1];
 387
 388         memcpy(buf, path, path_len + 1);
 389
 390         to_parent_name(buf, path_len);
 391
 392         return get_dentry(w, buf);
 393 }
 394
 395 /* Prints the full path of a dentry. */
 396 int print_dentry_full_path(struct dentry *dentry, void *ignore)
 397 {
 398         if (dentry->full_path_utf8)
 399                 puts(dentry->full_path_utf8);
 400         return 0;
 401 }
 402
 403 struct file_attr_flag {
 404         u32 flag;
 405         const char *name;
 406 };
 407 struct file_attr_flag file_attr_flags[] = {
 408         {FILE_ATTRIBUTE_READONLY,               "READONLY"},
 409         {FILE_ATTRIBUTE_HIDDEN,         "HIDDEN"},
 410         {FILE_ATTRIBUTE_SYSTEM,         "SYSTEM"},
 411         {FILE_ATTRIBUTE_DIRECTORY,              "DIRECTORY"},
 412         {FILE_ATTRIBUTE_ARCHIVE,                "ARCHIVE"},
 413         {FILE_ATTRIBUTE_DEVICE,         "DEVICE"},
 414         {FILE_ATTRIBUTE_NORMAL,         "NORMAL"},
 415         {FILE_ATTRIBUTE_TEMPORARY,              "TEMPORARY"},
 416         {FILE_ATTRIBUTE_SPARSE_FILE,    "SPARSE_FILE"},
 417         {FILE_ATTRIBUTE_REPARSE_POINT,  "REPARSE_POINT"},
 418         {FILE_ATTRIBUTE_COMPRESSED,             "COMPRESSED"},
 419         {FILE_ATTRIBUTE_OFFLINE,                "OFFLINE"},
 420         {FILE_ATTRIBUTE_NOT_CONTENT_INDEXED,"NOT_CONTENT_INDEXED"},
 421         {FILE_ATTRIBUTE_ENCRYPTED,              "ENCRYPTED"},
 422         {FILE_ATTRIBUTE_VIRTUAL,                "VIRTUAL"},
 423 };
 424
 425 /* Prints a directory entry.  @lookup_table is a pointer to the lookup table, or
 426  * NULL if the resource entry for the dentry is not to be printed. */
 427 int print_dentry(struct dentry *dentry, void *lookup_table)
 428 {
 429         const u8 *hash;
 430         struct lookup_table_entry *lte;
 431
 432         printf("[DENTRY]\n");
 433         printf("Length            = %"PRIu64"\n", dentry->length);
 434         printf("Attributes        = 0x%x\n", dentry->attributes);
 435         for (unsigned i = 0; i < ARRAY_LEN(file_attr_flags); i++)
 436                 if (file_attr_flags[i].flag & dentry->attributes)
 437                         printf("    FILE_ATTRIBUTE_%s is set\n",
 438                                 file_attr_flags[i].name);
 439         printf("Security ID       = %d\n", dentry->security_id);
 440         printf("Subdir offset     = %"PRIu64"\n", dentry->subdir_offset);
 441 #if 0
 442         printf("Unused1           = 0x%"PRIu64"\n", dentry->unused1);
 443         printf("Unused2           = %"PRIu64"\n", dentry->unused2);
 444 #endif
 445 #if 0
 446         printf("Creation Time     = 0x%"PRIx64"\n");
 447         printf("Last Access Time  = 0x%"PRIx64"\n");
 448         printf("Last Write Time   = 0x%"PRIx64"\n");
 449 #endif
 450
 451         time_t creat_time = wim_timestamp_to_unix(dentry->creation_time);
 452         time_t access_time = wim_timestamp_to_unix(dentry->last_access_time);
 453         time_t mod_time = wim_timestamp_to_unix(dentry->last_write_time);
 454         printf("Creation Time     = %s", asctime(localtime(&creat_time)));
 455         printf("Last Access Time  = %s", asctime(localtime(&access_time)));
 456         printf("Last Write Time   = %s", asctime(localtime(&mod_time)));
 457
 458         printf("Reparse Tag       = 0x%"PRIx32"\n", dentry->reparse_tag);
 459         printf("Hard Link Group   = 0x%"PRIx64"\n", dentry->hard_link);
 460         printf("Number of Alternate Data Streams = %hu\n", dentry->num_ads);
 461         printf("Filename          = \"");
 462         print_string(dentry->file_name, dentry->file_name_len);
 463         puts("\"");
 464         printf("Filename Length   = %hu\n", dentry->file_name_len);
 465         printf("Filename (UTF-8)  = \"%s\"\n", dentry->file_name_utf8);
 466         printf("Filename (UTF-8) Length = %hu\n", dentry->file_name_utf8_len);
 467         printf("Short Name        = \"");
 468         print_string(dentry->short_name, dentry->short_name_len);
 469         puts("\"");
 470         printf("Short Name Length = %hu\n", dentry->short_name_len);
 471         printf("Full Path (UTF-8) = \"%s\"\n", dentry->full_path_utf8);
 472         lte = dentry_stream_lte(dentry, 0, lookup_table);
 473         if (lte) {
 474                 print_lookup_table_entry(lte);
 475         } else {
 476                 hash = dentry_stream_hash(dentry, 0);
 477                 if (hash) {
 478                         printf("Hash              = 0x");
 479                         print_hash(hash);
 480                         putchar('\n');
 481                         putchar('\n');
 482                 }
 483         }
 484         for (u16 i = 0; i < dentry->num_ads; i++) {
 485                 printf("[Alternate Stream Entry %u]\n", i);
 486                 printf("Name = \"%s\"\n", dentry->ads_entries[i].stream_name_utf8);
 487                 printf("Name Length (UTF-16) = %u\n",
 488                                 dentry->ads_entries[i].stream_name_len);
 489                 hash = dentry_stream_hash(dentry, i + 1);
 490                 if (hash) {
 491                         printf("Hash              = 0x");
 492                         print_hash(hash);
 493                         putchar('\n');
 494                 }
 495                 print_lookup_table_entry(dentry_stream_lte(dentry, i + 1,
 496                                                            lookup_table));
 497         }
 498         return 0;
 499 }
 500
 501 static inline void dentry_common_init(struct dentry *dentry)
 502 {
 503         memset(dentry, 0, sizeof(struct dentry));
 504         dentry->refcnt = 1;
 505         dentry->security_id = -1;
 506         dentry->ads_entries_status = ADS_ENTRIES_DEFAULT;
 507         dentry->lte_group_list.type = STREAM_TYPE_NORMAL;
 508 }
 509
 510 /*
 511  * Creates an unlinked directory entry.
 512  *
 513  * @name:    The base name of the new dentry.
 514  * @return:  A pointer to the new dentry, or NULL if out of memory.
 515  */
 516 struct dentry *new_dentry(const char *name)
 517 {
 518         struct dentry *dentry;
 519
 520         dentry = MALLOC(sizeof(struct dentry));
 521         if (!dentry)
 522                 goto err;
 523
 524         dentry_common_init(dentry);
 525         if (change_dentry_name(dentry, name) != 0)
 526                 goto err;
 527
 528         dentry_update_all_timestamps(dentry);
 529         dentry->next   = dentry;
 530         dentry->prev   = dentry;
 531         dentry->parent = dentry;
 532         INIT_LIST_HEAD(&dentry->link_group_list);
 533         return dentry;
 534 err:
 535         FREE(dentry);
 536         ERROR("Failed to allocate new dentry");
 537         return NULL;
 538 }
 539
 540 void dentry_free_ads_entries(struct dentry *dentry)
 541 {
 542         for (u16 i = 0; i < dentry->num_ads; i++)
 543                 destroy_ads_entry(&dentry->ads_entries[i]);
 544         FREE(dentry->ads_entries);
 545         dentry->ads_entries = NULL;
 546         dentry->num_ads = 0;
 547 }
 548
 549 static void __destroy_dentry(struct dentry *dentry)
 550 {
 551         FREE(dentry->file_name);
 552         FREE(dentry->file_name_utf8);
 553         FREE(dentry->short_name);
 554         FREE(dentry->full_path_utf8);
 555         FREE(dentry->extracted_file);
 556 }
 557
 558 void free_dentry(struct dentry *dentry)
 559 {
 560         wimlib_assert(dentry);
 561         __destroy_dentry(dentry);
 562         if (dentry->ads_entries_status != ADS_ENTRIES_USER)
 563                 dentry_free_ads_entries(dentry);
 564         FREE(dentry);
 565 }
 566
 567 /* Like free_dentry(), but assigns a new ADS entries owner if this dentry was
 568  * the previous owner, and also deletes the dentry from its link_group_list */
 569 void put_dentry(struct dentry *dentry)
 570 {
 571         if (dentry->ads_entries_status == ADS_ENTRIES_OWNER) {
 572                 struct dentry *new_owner;
 573                 list_for_each_entry(new_owner, &dentry->link_group_list,
 574                                     link_group_list)
 575                 {
 576                         if (new_owner->ads_entries_status == ADS_ENTRIES_USER) {
 577                                 new_owner->ads_entries_status = ADS_ENTRIES_OWNER;
 578                                 break;
 579                         }
 580                 }
 581                 dentry->ads_entries_status = ADS_ENTRIES_USER;
 582         }
 583         struct list_head *next;
 584         list_del(&dentry->link_group_list);
 585         free_dentry(dentry);
 586 }
 587
 588
 589 /* clones a dentry.
 590  *
 591  * Beware:
 592  *      - memory for file names is not cloned
 593  *      - next, prev, and children pointers and not touched
 594  *      - stream entries are not cloned.
 595  */
 596 struct dentry *clone_dentry(struct dentry *old)
 597 {
 598         struct dentry *new = MALLOC(sizeof(struct dentry));
 599         if (!new)
 600                 return NULL;
 601         memcpy(new, old, sizeof(struct dentry));
 602         new->file_name          = NULL;
 603         new->file_name_len      = 0;
 604         new->file_name_utf8     = NULL;
 605         new->file_name_utf8_len = 0;
 606         new->short_name         = NULL;
 607         new->short_name_len     = 0;
 608         return new;
 609 }
 610
 611 /*
 612  * This function is passed as an argument to for_dentry_in_tree_depth() in order
 613  * to free a directory tree.  __args is a pointer to a `struct free_dentry_args'.
 614  */
 615 static int do_free_dentry(struct dentry *dentry, void *__lookup_table)
 616 {
 617         struct lookup_table *lookup_table = __lookup_table;
 618         if (lookup_table) {
 619                 struct lookup_table_entry *lte;
 620                 if (dentry->resolved)
 621                         lte = dentry->lte;
 622                 else
 623                         lte = __lookup_resource(lookup_table, dentry->hash);
 624                 lte_decrement_refcnt(lte, lookup_table);
 625         }
 626
 627         wimlib_assert(dentry->refcnt != 0);
 628         if (--dentry->refcnt == 0)
 629                 free_dentry(dentry);
 630         return 0;
 631 }
 632
 633 /*
 634  * Unlinks and frees a dentry tree.
 635  *
 636  * @root:               The root of the tree.
 637  * @lookup_table:       The lookup table for dentries.  If non-NULL, the
 638  *                      reference counts in the lookup table for the lookup
 639  *                      table entries corresponding to the dentries will be
 640  *                      decremented.
 641  */
 642 void free_dentry_tree(struct dentry *root, struct lookup_table *lookup_table)
 643 {
 644         if (!root || !root->parent)
 645                 return;
 646         for_dentry_in_tree_depth(root, do_free_dentry, lookup_table);
 647 }
 648
 649 int increment_dentry_refcnt(struct dentry *dentry, void *ignore)
 650 {
 651         dentry->refcnt++;
 652         return 0;
 653 }
 654
 655 /*
 656  * Links a dentry into the directory tree.
 657  *
 658  * @dentry: The dentry to link.
 659  * @parent: The dentry that will be the parent of @dentry.
 660  */
 661 void link_dentry(struct dentry *dentry, struct dentry *parent)
 662 {
 663         wimlib_assert(dentry_is_directory(parent));
 664         dentry->parent = parent;
 665         if (parent->children) {
 666                 /* Not an only child; link to siblings. */
 667                 dentry->next = parent->children;
 668                 dentry->prev = parent->children->prev;
 669                 dentry->next->prev = dentry;
 670                 dentry->prev->next = dentry;
 671         } else {
 672                 /* Only child; link to parent. */
 673                 parent->children = dentry;
 674                 dentry->next = dentry;
 675                 dentry->prev = dentry;
 676         }
 677 }
 678
 679
 680 /* Unlink a dentry from the directory tree.
 681  *
 682  * Note: This merely removes it from the in-memory tree structure.  See
 683  * remove_dentry() in mount.c for a function implemented on top of this one that
 684  * frees the dentry and implements reference counting for the lookup table
 685  * entries. */
 686 void unlink_dentry(struct dentry *dentry)
 687 {
 688         if (dentry_is_root(dentry))
 689                 return;
 690         if (dentry_is_only_child(dentry)) {
 691                 dentry->parent->children = NULL;
 692         } else {
 693                 if (dentry_is_first_sibling(dentry))
 694                         dentry->parent->children = dentry->next;
 695                 dentry->next->prev = dentry->prev;
 696                 dentry->prev->next = dentry->next;
 697         }
 698 }
 699
 700
 701 /* Recalculates the length of @dentry based on its file name length and short
 702  * name length.  */
 703 static inline void recalculate_dentry_size(struct dentry *dentry)
 704 {
 705         dentry->length = WIM_DENTRY_DISK_SIZE + dentry->file_name_len +
 706                          2 + dentry->short_name_len;
 707         /* Must be multiple of 8. */
 708         dentry->length = (dentry->length + 7) & ~7;
 709 }
 710
 711 /* Duplicates a UTF-8 name into UTF-8 and UTF-16 strings and returns the strings
 712  * and their lengths in the pointer arguments */
 713 int get_names(char **name_utf16_ret, char **name_utf8_ret,
 714               u16 *name_utf16_len_ret, u16 *name_utf8_len_ret,
 715               const char *name)
 716 {
 717         size_t utf8_len;
 718         size_t utf16_len;
 719         char *name_utf16, *name_utf8;
 720
 721         utf8_len = strlen(name);
 722
 723         name_utf16 = utf8_to_utf16(name, utf8_len, &utf16_len);
 724
 725         if (!name_utf16)
 726                 return WIMLIB_ERR_NOMEM;
 727
 728         name_utf8 = MALLOC(utf8_len + 1);
 729         if (!name_utf8) {
 730                 FREE(name_utf8);
 731                 return WIMLIB_ERR_NOMEM;
 732         }
 733         memcpy(name_utf8, name, utf8_len + 1);
 734         FREE(*name_utf8_ret);
 735         FREE(*name_utf16_ret);
 736         *name_utf8_ret      = name_utf8;
 737         *name_utf16_ret     = name_utf16;
 738         *name_utf8_len_ret  = utf8_len;
 739         *name_utf16_len_ret = utf16_len;
 740         return 0;
 741 }
 742
 743 /* Changes the name of a dentry to @new_name.  Only changes the file_name and
 744  * file_name_utf8 fields; does not change the short_name, short_name_utf8, or
 745  * full_path_utf8 fields.  Also recalculates its length. */
 746 int change_dentry_name(struct dentry *dentry, const char *new_name)
 747 {
 748         int ret;
 749
 750         ret = get_names(&dentry->file_name, &dentry->file_name_utf8,
 751                         &dentry->file_name_len, &dentry->file_name_utf8_len,
 752                          new_name);
 753         if (ret == 0)
 754                 recalculate_dentry_size(dentry);
 755         return ret;
 756 }
 757
 758 int change_ads_name(struct ads_entry *entry, const char *new_name)
 759 {
 760         return get_names(&entry->stream_name, &entry->stream_name_utf8,
 761                          &entry->stream_name_len,
 762                          &entry->stream_name_utf8_len,
 763                          new_name);
 764 }
 765
 766 /* Parameters for calculate_dentry_statistics(). */
 767 struct image_statistics {
 768         struct lookup_table *lookup_table;
 769         u64 *dir_count;
 770         u64 *file_count;
 771         u64 *total_bytes;
 772         u64 *hard_link_bytes;
 773 };
 774
 775 static int calculate_dentry_statistics(struct dentry *dentry, void *arg)
 776 {
 777         struct image_statistics *stats;
 778         struct lookup_table_entry *lte;
 779         u16 i;
 780
 781         stats = arg;
 782
 783         if (dentry_is_directory(dentry) && !dentry_is_root(dentry))
 784                 ++*stats->dir_count;
 785         else
 786                 ++*stats->file_count;
 787
 788         if (dentry->resolved)
 789                 lte = dentry->lte;
 790         else
 791                 lte = __lookup_resource(stats->lookup_table, dentry->hash);
 792         i = 0;
 793         while (1) {
 794                 if (lte) {
 795                         u64 size = lte->resource_entry.original_size;
 796                         *stats->total_bytes += size;
 797                         if (++lte->out_refcnt == 1)
 798                                 *stats->hard_link_bytes += size;
 799                 }
 800                 if (i == dentry->num_ads)
 801                         break;
 802                 lte = __lookup_resource(stats->lookup_table,
 803                                         dentry->ads_entries[i].hash);
 804                 i++;
 805         }
 806
 807         return 0;
 808 }
 809
 810 void calculate_dir_tree_statistics(struct dentry *root, struct lookup_table *table,
 811                                    u64 *dir_count_ret, u64 *file_count_ret,
 812                                    u64 *total_bytes_ret,
 813                                    u64 *hard_link_bytes_ret)
 814 {
 815         struct image_statistics stats;
 816         *dir_count_ret         = 0;
 817         *file_count_ret        = 0;
 818         *total_bytes_ret       = 0;
 819         *hard_link_bytes_ret   = 0;
 820         stats.lookup_table     = table;
 821         stats.dir_count       = dir_count_ret;
 822         stats.file_count      = file_count_ret;
 823         stats.total_bytes     = total_bytes_ret;
 824         stats.hard_link_bytes = hard_link_bytes_ret;
 825         for_lookup_table_entry(table, zero_out_refcnts, NULL);
 826         for_dentry_in_tree(root, calculate_dentry_statistics, &stats);
 827 }
 828
 829 static int read_ads_entries(const u8 *p, struct dentry *dentry,
 830                             u64 remaining_size)
 831 {
 832         u16 num_ads = dentry->num_ads;
 833         struct ads_entry *ads_entries = CALLOC(num_ads, sizeof(struct ads_entry));
 834         int ret;
 835         if (!ads_entries) {
 836                 ERROR("Could not allocate memory for %"PRIu16" "
 837                       "alternate data stream entries", num_ads);
 838                 return WIMLIB_ERR_NOMEM;
 839         }
 840         DEBUG2("Reading %"PRIu16" alternate data streams "
 841                "(remaining size = %"PRIu64")", num_ads, remaining_size);
 842
 843         for (u16 i = 0; i < num_ads; i++) {
 844                 struct ads_entry *cur_entry = &ads_entries[i];
 845                 u64 length;
 846                 size_t utf8_len;
 847                 const char *p_save = p;
 848                 /* Read the base stream entry, excluding the stream name. */
 849                 if (remaining_size < WIM_ADS_ENTRY_DISK_SIZE) {
 850                         ERROR("Stream entries go past end of metadata resource");
 851                         ERROR("(remaining_size = %"PRIu64")", remaining_size);
 852                         ret = WIMLIB_ERR_INVALID_DENTRY;
 853                         goto out_free_ads_entries;
 854                 }
 855                 remaining_size -= WIM_ADS_ENTRY_DISK_SIZE;
 856
 857                 p = get_u64(p, &length); /* ADS entry length */
 858
 859                 DEBUG2("ADS length = %"PRIu64, length);
 860
 861                 p += 8; /* Unused */
 862                 p = get_bytes(p, SHA1_HASH_SIZE, (u8*)cur_entry->hash);
 863                 p = get_u16(p, &cur_entry->stream_name_len);
 864
 865                 DEBUG2("Stream name length = %u", cur_entry->stream_name_len);
 866
 867                 cur_entry->stream_name = NULL;
 868                 cur_entry->stream_name_utf8 = NULL;
 869
 870                 if (remaining_size < cur_entry->stream_name_len + 2) {
 871                         ERROR("Stream entries go past end of metadata resource");
 872                         ERROR("(remaining_size = %"PRIu64" bytes, stream_name_len "
 873                               "= %"PRIu16" bytes", remaining_size,
 874                               cur_entry->stream_name_len);
 875                         ret = WIMLIB_ERR_INVALID_DENTRY;
 876                         goto out_free_ads_entries;
 877                 }
 878                 remaining_size -= cur_entry->stream_name_len + 2;
 879
 880                 cur_entry->stream_name = MALLOC(cur_entry->stream_name_len);
 881                 if (!cur_entry->stream_name) {
 882                         ret = WIMLIB_ERR_NOMEM;
 883                         goto out_free_ads_entries;
 884                 }
 885                 get_bytes(p, cur_entry->stream_name_len,
 886                           (u8*)cur_entry->stream_name);
 887                 cur_entry->stream_name_utf8 = utf16_to_utf8(cur_entry->stream_name,
 888                                                             cur_entry->stream_name_len,
 889                                                             &utf8_len);
 890                 cur_entry->stream_name_utf8_len = utf8_len;
 891
 892                 if (!cur_entry->stream_name_utf8) {
 893                         ret = WIMLIB_ERR_NOMEM;
 894                         goto out_free_ads_entries;
 895                 }
 896                 p = p_save + ads_entry_length(cur_entry);
 897         }
 898         dentry->ads_entries = ads_entries;
 899         return 0;
 900 out_free_ads_entries:
 901         for (u16 i = 0; i < num_ads; i++) {
 902                 FREE(ads_entries[i].stream_name);
 903                 FREE(ads_entries[i].stream_name_utf8);
 904         }
 905         FREE(ads_entries);
 906         return ret;
 907 }
 908
 909 /*
 910  * Reads a directory entry from the metadata resource.
 911  */
 912 int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
 913                 u64 offset, struct dentry *dentry)
 914 {
 915         const u8 *p;
 916         u64 calculated_size;
 917         char *file_name;
 918         char *file_name_utf8;
 919         char *short_name;
 920         u16 short_name_len;
 921         u16 file_name_len;
 922         size_t file_name_utf8_len;
 923         int ret;
 924
 925         dentry_common_init(dentry);
 926
 927         /*Make sure the dentry really fits into the metadata resource.*/
 928         if (offset + 8 > metadata_resource_len) {
 929                 ERROR("Directory entry starting at %"PRIu64" ends past the "
 930                       "end of the metadata resource (size %"PRIu64")",
 931                       offset, metadata_resource_len);
 932                 return WIMLIB_ERR_INVALID_DENTRY;
 933         }
 934
 935         /* Before reading the whole entry, we need to read just the length.
 936          * This is because an entry of length 8 (that is, just the length field)
 937          * terminates the list of sibling directory entries. */
 938
 939         p = get_u64(&metadata_resource[offset], &dentry->length);
 940
 941         /* A zero length field (really a length of 8, since that's how big the
 942          * directory entry is...) indicates that this is the end of directory
 943          * dentry.  We do not read it into memory as an actual dentry, so just
 944          * return true in that case. */
 945         if (dentry->length == 0)
 946                 return 0;
 947
 948         if (offset + dentry->length >= metadata_resource_len) {
 949                 ERROR("Directory entry at offset %"PRIu64" and with size "
 950                       "%"PRIu64" ends past the end of the metadata resource "
 951                       "(size %"PRIu64")",
 952                       offset, dentry->length, metadata_resource_len);
 953                 return WIMLIB_ERR_INVALID_DENTRY;
 954         }
 955
 956         /* If it is a recognized length, read the rest of the directory entry.
 957          * Note: The root directory entry has no name, and its length does not
 958          * include the short name length field.  */
 959         if (dentry->length < WIM_DENTRY_DISK_SIZE) {
 960                 ERROR("Directory entry has invalid length of %"PRIu64" bytes",
 961                       dentry->length);
 962                 return WIMLIB_ERR_INVALID_DENTRY;
 963         }
 964
 965         p = get_u32(p, &dentry->attributes);
 966         p = get_u32(p, (u32*)&dentry->security_id);
 967         p = get_u64(p, &dentry->subdir_offset);
 968
 969         /* 2 unused fields */
 970         p += 2 * sizeof(u64);
 971         /*p = get_u64(p, &dentry->unused1);*/
 972         /*p = get_u64(p, &dentry->unused2);*/
 973
 974         p = get_u64(p, &dentry->creation_time);
 975         p = get_u64(p, &dentry->last_access_time);
 976         p = get_u64(p, &dentry->last_write_time);
 977
 978         p = get_bytes(p, SHA1_HASH_SIZE, dentry->hash);
 979
 980         /*
 981          * I don't know what's going on here.  It seems like M$ screwed up the
 982          * reparse points, then put the fields in the same place and didn't
 983          * document it.  The WIM_HDR_FLAG_RP_FIX flag in the WIM header might
 984          * have something to do with this, but it's not documented.
 985          */
 986         if (dentry->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
 987                 /* ??? */
 988                 p += 4;
 989                 p = get_u32(p, &dentry->reparse_tag);
 990                 p += 4;
 991         } else {
 992                 p = get_u32(p, &dentry->reparse_tag);
 993                 p = get_u64(p, &dentry->hard_link);
 994         }
 995
 996         /* By the way, the reparse_reserved field does not actually exist (at
 997          * least when the file is not a reparse point) */
 998
 999
1000         p = get_u16(p, &dentry->num_ads);
1001
1002         p = get_u16(p, &short_name_len);
1003         p = get_u16(p, &file_name_len);
1004
1005         calculated_size = WIM_DENTRY_DISK_SIZE + file_name_len + 2 +
1006                           short_name_len;
1007
1008         if (dentry->length < calculated_size) {
1009                 ERROR("Unexpected end of directory entry! (Expected "
1010                       "%"PRIu64" bytes, got %"PRIu64" bytes. "
1011                       "short_name_len = %hu, file_name_len = %hu)",
1012                       calculated_size, dentry->length,
1013                       short_name_len, file_name_len);
1014                 return WIMLIB_ERR_INVALID_DENTRY;
1015         }
1016
1017         /* Read the filename. */
1018         file_name = MALLOC(file_name_len);
1019         if (!file_name) {
1020                 ERROR("Failed to allocate %hu bytes for dentry file name",
1021                       file_name_len);
1022                 return WIMLIB_ERR_NOMEM;
1023         }
1024         p = get_bytes(p, file_name_len, file_name);
1025
1026         /* Convert filename to UTF-8. */
1027         file_name_utf8 = utf16_to_utf8(file_name, file_name_len,
1028                                        &file_name_utf8_len);
1029
1030         if (!file_name_utf8) {
1031                 ERROR("Failed to allocate memory to convert UTF-16 "
1032                       "filename (%hu bytes) to UTF-8", file_name_len);
1033                 ret = WIMLIB_ERR_NOMEM;
1034                 goto out_free_file_name;
1035         }
1036
1037         /* Undocumented padding between file name and short name.  This probably
1038          * is supposed to be a terminating null character. */
1039         p += 2;
1040
1041         /* Read the short filename. */
1042         short_name = MALLOC(short_name_len);
1043         if (!short_name) {
1044                 ERROR("Failed to allocate %hu bytes for short filename",
1045                       short_name_len);
1046                 ret = WIMLIB_ERR_NOMEM;
1047                 goto out_free_file_name_utf8;
1048         }
1049
1050         p = get_bytes(p, short_name_len, short_name);
1051
1052         /* Some directory entries inexplicibly have a little over 70 bytes of
1053          * extra data.  The exact amount of data seems to be 72 bytes, but it is
1054          * aligned on the next 8-byte boundary.  Here's an example of the
1055          * aligned data:
1056          *
1057          * 01000000 40000000 6c786bba c58ede11 b0bb0026 1870892a b6adb76f
1058          * e63a3e46 8fca8653 0d2effa1 6c786bba c58ede11 b0bb0026 1870892a
1059          * 00000000 00000000 00000000 00000000
1060          *
1061          * Here's one interpretation of how the data is laid out.
1062          *
1063          * struct unknown {
1064          *      u32 field1; (always 0x00000001)
1065          *      u32 field2; (always 0x40000000)
1066          *      u8  data[48]; (???)
1067          *      u64 reserved1; (always 0)
1068          *      u64 reserved2; (always 0)
1069          * };*/
1070 #if 0
1071         if (dentry->length - calculated_size >= WIM_ADS_ENTRY_DISK_SIZE) {
1072                 printf("%s: %lu / %lu (", file_name_utf8,
1073                                 calculated_size, dentry->length);
1074                 print_string(p + WIM_ADS_ENTRY_DISK_SIZE, dentry->length - calculated_size - WIM_ADS_ENTRY_DISK_SIZE);
1075                 puts(")");
1076                 print_byte_field(p, dentry->length - calculated_size);
1077                 putchar('\n');
1078         }
1079 #endif
1080
1081         if (dentry->num_ads != 0) {
1082                 calculated_size = (calculated_size + 7) & ~7;
1083                 if (calculated_size > metadata_resource_len - offset) {
1084                         ERROR("Not enough space in metadata resource for "
1085                               "alternate stream entries");
1086                         ret = WIMLIB_ERR_INVALID_DENTRY;
1087                         goto out_free_short_name;
1088                 }
1089                 ret = read_ads_entries(&metadata_resource[offset + calculated_size],
1090                                        dentry,
1091                                        metadata_resource_len - offset - calculated_size);
1092                 if (ret != 0)
1093                         goto out_free_short_name;
1094         }
1095
1096         dentry->file_name          = file_name;
1097         dentry->file_name_utf8     = file_name_utf8;
1098         dentry->short_name         = short_name;
1099         dentry->file_name_len      = file_name_len;
1100         dentry->file_name_utf8_len = file_name_utf8_len;
1101         dentry->short_name_len     = short_name_len;
1102         return 0;
1103 out_free_short_name:
1104         FREE(short_name);
1105 out_free_file_name_utf8:
1106         FREE(file_name_utf8);
1107 out_free_file_name:
1108         FREE(file_name);
1109         return ret;
1110 }
1111
1112 /*
1113  * Writes a dentry to an output buffer.
1114  *
1115  * @dentry:  The dentry structure.
1116  * @p:       The memory location to write the data to.
1117  * @return:  Pointer to the byte after the last byte we wrote as part of the
1118  *              dentry.
1119  */
1120 static u8 *write_dentry(const struct dentry *dentry, u8 *p)
1121 {
1122         u8 *orig_p = p;
1123         unsigned padding;
1124         const u8 *hash;
1125
1126         p = put_u64(p, dentry->length);
1127         p = put_u32(p, dentry->attributes);
1128         p = put_u32(p, dentry->security_id);
1129         p = put_u64(p, dentry->subdir_offset);
1130         p = put_u64(p, 0); /* unused1 */
1131         p = put_u64(p, 0); /* unused2 */
1132         p = put_u64(p, dentry->creation_time);
1133         p = put_u64(p, dentry->last_access_time);
1134         p = put_u64(p, dentry->last_write_time);
1135         if (dentry->resolved && dentry->lte)
1136                 hash = dentry->lte->hash;
1137         else
1138                 hash = dentry->hash;
1139         p = put_bytes(p, SHA1_HASH_SIZE, hash);
1140         if (dentry->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
1141                 p = put_zeroes(p, 4);
1142                 p = put_u32(p, dentry->reparse_tag);
1143                 p = put_zeroes(p, 4);
1144         } else {
1145                 u64 hard_link;
1146                 p = put_u32(p, dentry->reparse_tag);
1147                 if (dentry->link_group_list.next == &dentry->link_group_list)
1148                         hard_link = 0;
1149                 else
1150                         hard_link = dentry->hard_link;
1151                 p = put_u64(p, hard_link);
1152         }
1153         p = put_u16(p, dentry->num_ads);
1154         p = put_u16(p, dentry->short_name_len);
1155         p = put_u16(p, dentry->file_name_len);
1156         p = put_bytes(p, dentry->file_name_len, (u8*)dentry->file_name);
1157         p = put_u16(p, 0); /* filename padding, 2 bytes. */
1158         p = put_bytes(p, dentry->short_name_len, (u8*)dentry->short_name);
1159
1160         wimlib_assert(p - orig_p <= dentry->length);
1161         if (p - orig_p < dentry->length)
1162                 p = put_zeroes(p, dentry->length - (p - orig_p));
1163
1164         p = put_zeroes(p, (8 - dentry->length % 8) % 8);
1165
1166         for (u16 i = 0; i < dentry->num_ads; i++) {
1167                 p = put_u64(p, ads_entry_length(&dentry->ads_entries[i]));
1168                 p = put_u64(p, 0); /* Unused */
1169                 if (dentry->resolved && dentry->ads_entries[i].lte)
1170                         hash = dentry->ads_entries[i].lte->hash;
1171                 else
1172                         hash = dentry->ads_entries[i].hash;
1173                 p = put_bytes(p, SHA1_HASH_SIZE, hash);
1174                 p = put_u16(p, dentry->ads_entries[i].stream_name_len);
1175                 p = put_bytes(p, dentry->ads_entries[i].stream_name_len,
1176                                  (u8*)dentry->ads_entries[i].stream_name);
1177                 p = put_u16(p, 0);
1178                 p = put_zeroes(p, (8 - (p - orig_p) % 8) % 8);
1179         }
1180         return p;
1181 }
1182
1183 /* Recursive function that writes a dentry tree rooted at @tree, not including
1184  * @tree itself, which has already been written, except in the case of the root
1185  * dentry, which is written right away, along with an end-of-directory entry. */
1186 u8 *write_dentry_tree(const struct dentry *tree, u8 *p)
1187 {
1188         const struct dentry *child;
1189
1190         if (dentry_is_root(tree)) {
1191                 p = write_dentry(tree, p);
1192
1193                 /* write end of directory entry */
1194                 p = put_u64(p, 0);
1195         } else {
1196                 /* Nothing to do for non-directories */
1197                 if (!dentry_is_directory(tree))
1198                         return p;
1199         }
1200
1201         /* Write child dentries and end-of-directory entry. */
1202         child = tree->children;
1203         if (child) {
1204                 do {
1205                         p = write_dentry(child, p);
1206                         child = child->next;
1207                 } while (child != tree->children);
1208         }
1209
1210         /* write end of directory entry */
1211         p = put_u64(p, 0);
1212
1213         /* Recurse on children. */
1214         if (child) {
1215                 do {
1216                         p = write_dentry_tree(child, p);
1217                         child = child->next;
1218                 } while (child != tree->children);
1219         }
1220         return p;
1221 }
1222
1223 /* Reads the children of a dentry, and all their children, ..., etc. from the
1224  * metadata resource and into the dentry tree.
1225  *
1226  * @metadata_resource:  An array that contains the uncompressed metadata
1227  *                      resource for the WIM file.
1228  * @metadata_resource_len:      The length of @metadata_resource.
1229  * @dentry:     A pointer to a struct dentry that is the root of the directory
1230  *              tree and has already been read from the metadata resource.  It
1231  *              does not need to be the real root because this procedure is
1232  *              called recursively.
1233  *
1234  * @return:     Zero on success, nonzero on failure.
1235  */
1236 int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
1237                      struct dentry *dentry)
1238 {
1239         u64 cur_offset = dentry->subdir_offset;
1240         struct dentry *prev_child = NULL;
1241         struct dentry *first_child = NULL;
1242         struct dentry *child;
1243         struct dentry cur_child;
1244         int ret;
1245
1246         /* If @dentry is a regular file, nothing more needs to be done for this
1247          * branch. */
1248         if (cur_offset == 0)
1249                 return 0;
1250
1251         /* Find and read all the children of @dentry. */
1252         while (1) {
1253
1254                 /* Read next child of @dentry into @cur_child. */
1255                 ret = read_dentry(metadata_resource, metadata_resource_len,
1256                                   cur_offset, &cur_child);
1257                 if (ret != 0)
1258                         break;
1259
1260                 /* Check for end of directory. */
1261                 if (cur_child.length == 0) {
1262                         ret = 0;
1263                         break;
1264                 }
1265
1266                 /* Not end of directory.  Allocate this child permanently and
1267                  * link it to the parent and previous child. */
1268                 child = MALLOC(sizeof(struct dentry));
1269                 if (!child) {
1270                         ERROR("Failed to allocate %zu bytes for new dentry",
1271                               sizeof(struct dentry));
1272                         ret = WIMLIB_ERR_NOMEM;
1273                         break;
1274                 }
1275                 memcpy(child, &cur_child, sizeof(struct dentry));
1276
1277                 if (prev_child) {
1278                         prev_child->next = child;
1279                         child->prev = prev_child;
1280                 } else {
1281                         first_child = child;
1282                 }
1283
1284                 child->parent = dentry;
1285                 prev_child = child;
1286
1287                 /* If there are children of this child, call this procedure
1288                  * recursively. */
1289                 if (child->subdir_offset != 0) {
1290                         ret = read_dentry_tree(metadata_resource,
1291                                                metadata_resource_len, child);
1292                         if (ret != 0)
1293                                 break;
1294                 }
1295
1296                 /* Advance to the offset of the next child. */
1297                 cur_offset += dentry_total_length(child);
1298         }
1299
1300         /* Link last child to first one, and set parent's
1301          * children pointer to the first child.  */
1302         if (prev_child) {
1303                 prev_child->next = first_child;
1304                 first_child->prev = prev_child;
1305         }
1306         dentry->children = first_child;
1307         return ret;
1308 }