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