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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  * Copyright (C) 2010 Carl Thijssen
  12  * Copyright (C) 2012 Eric Biggers
  13  *
  14  * wimlib - Library for working with WIM files
  15  *
  16  * This library is free software; you can redistribute it and/or modify it under
  17  * the terms of the GNU Lesser General Public License as published by the Free
  18  * Software Foundation; either version 2.1 of the License, or (at your option) any
  19  * later version.
  20  *
  21  * This library is distributed in the hope that it will be useful, but WITHOUT ANY
  22  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
  23  * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU Lesser General Public License along
  26  * with this library; if not, write to the Free Software Foundation, Inc., 59
  27  * Temple Place, Suite 330, Boston, MA 02111-1307 USA
  28  */
  29
  30 #include "wimlib_internal.h"
  31 #include "dentry.h"
  32 #include "io.h"
  33 #include "timestamp.h"
  34 #include "lookup_table.h"
  35 #include <unistd.h>
  36 #include <sys/stat.h>
  37
  38
  39 /* Transfers file attributes from a `stat' buffer to a struct dentry. */
  40 void stbuf_to_dentry(const struct stat *stbuf, struct dentry *dentry)
  41 {
  42         if (S_ISDIR(stbuf->st_mode))
  43                 dentry->attributes = WIM_FILE_ATTRIBUTE_DIRECTORY;
  44         else
  45                 dentry->attributes = WIM_FILE_ATTRIBUTE_NORMAL;
  46 }
  47
  48 /* Transfers file attributes from a struct dentry to a `stat' buffer. */
  49 void dentry_to_stbuf(const struct dentry *dentry, struct stat *stbuf,
  50                      const struct lookup_table *table)
  51 {
  52         struct lookup_table_entry *lte;
  53
  54         if (dentry_is_directory(dentry))
  55                 stbuf->st_mode = S_IFDIR | 0755;
  56         else
  57                 stbuf->st_mode = S_IFREG | 0644;
  58
  59         if (table)
  60                 lte = lookup_resource(table, dentry->hash);
  61         else
  62                 lte = NULL;
  63
  64         if (lte) {
  65                 stbuf->st_nlink = lte->refcnt;
  66                 stbuf->st_size = lte->resource_entry.original_size;
  67         } else {
  68                 stbuf->st_nlink = 1;
  69                 stbuf->st_size = 0;
  70         }
  71         stbuf->st_uid     = getuid();
  72         stbuf->st_gid     = getgid();
  73         stbuf->st_atime   = ms_timestamp_to_unix(dentry->last_access_time);
  74         stbuf->st_mtime   = ms_timestamp_to_unix(dentry->last_write_time);
  75         stbuf->st_ctime   = ms_timestamp_to_unix(dentry->creation_time);
  76         stbuf->st_blocks  = (stbuf->st_size + 511) / 512;
  77 }
  78
  79 /* Makes all timestamp fields for the dentry be the current time. */
  80 void dentry_update_all_timestamps(struct dentry *dentry)
  81 {
  82         u64 now = get_timestamp();
  83         dentry->creation_time       = now;
  84         dentry->last_access_time    = now;
  85         dentry->last_write_time     = now;
  86 }
  87
  88 /*
  89  * Calls a function on all directory entries in a directory tree.  It is called
  90  * on a parent before its children.
  91  */
  92 int for_dentry_in_tree(struct dentry *root,
  93                        int (*visitor)(struct dentry*, void*), void *arg)
  94 {
  95         int ret;
  96         struct dentry *child;
  97
  98         ret = visitor(root, arg);
  99
 100         if (ret != 0)
 101                 return ret;
 102
 103         child = root->children;
 104
 105         if (!child)
 106                 return 0;
 107
 108         do {
 109                 ret = for_dentry_in_tree(child, visitor, arg);
 110                 if (ret != 0)
 111                         return ret;
 112                 child = child->next;
 113         } while (child != root->children);
 114         return 0;
 115 }
 116
 117 /*
 118  * Like for_dentry_in_tree(), but the visitor function is always called on a
 119  * dentry's children before on itself.
 120  */
 121 int for_dentry_in_tree_depth(struct dentry *root,
 122                              int (*visitor)(struct dentry*, void*), void *arg)
 123 {
 124         int ret;
 125         struct dentry *child;
 126         struct dentry *next;
 127
 128         child = root->children;
 129         if (child) {
 130                 do {
 131                         next = child->next;
 132                         ret = for_dentry_in_tree_depth(child, visitor, arg);
 133                         if (ret != 0)
 134                                 return ret;
 135                         child = next;
 136                 } while (child != root->children);
 137         }
 138         return visitor(root, arg);
 139 }
 140
 141 /*
 142  * Calculate the full path of @dentry, based on its parent's full path and on
 143  * its UTF-8 file name.
 144  */
 145 int calculate_dentry_full_path(struct dentry *dentry, void *ignore)
 146 {
 147         int parent_len;
 148         int len;
 149         char *parent_full_path;
 150         char *full_path;
 151
 152         FREE(dentry->full_path_utf8);
 153
 154         if (dentry_is_root(dentry)) {
 155                 dentry->full_path_utf8 = MALLOC(2);
 156                 if (!dentry->full_path_utf8) {
 157                         ERROR("Out of memory!\n");
 158                         return WIMLIB_ERR_NOMEM;
 159                 }
 160
 161                 dentry->full_path_utf8[0] = '/';
 162                 dentry->full_path_utf8[1] = '\0';
 163                 dentry->full_path_utf8_len = 1;
 164                 return 0;
 165         }
 166
 167         if (dentry_is_root(dentry->parent)) {
 168                 parent_len = 0;
 169                 parent_full_path = "";
 170         } else {
 171                 parent_len = dentry->parent->full_path_utf8_len;
 172                 parent_full_path = dentry->parent->full_path_utf8;
 173         }
 174
 175         len = parent_len + 1 + dentry->file_name_utf8_len;
 176         full_path = MALLOC(len + 1);
 177         if (!full_path) {
 178                 ERROR("Out of memory!\n");
 179                 return WIMLIB_ERR_NOMEM;
 180         }
 181
 182         memcpy(full_path, parent_full_path, parent_len);
 183         full_path[parent_len] = '/';
 184         memcpy(full_path + parent_len + 1, dentry->file_name_utf8,
 185                                 dentry->file_name_utf8_len);
 186         full_path[len] = '\0';
 187         dentry->full_path_utf8 = full_path;
 188         dentry->full_path_utf8_len = len;
 189         return 0;
 190 }
 191
 192 /*
 193  * Recursively calculates the subdir offsets for a directory tree.
 194  *
 195  * @dentry:  The root of the directory tree.
 196  * @subdir_offset_p:  The current subdirectory offset; i.e., the subdirectory
 197  *      offset for @dentry.
 198  */
 199 void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
 200 {
 201         struct dentry *child;
 202
 203         child = dentry->children;
 204         dentry->subdir_offset = *subdir_offset_p;
 205         if (child) {
 206
 207                 /* Advance the subdir offset by the amount of space the children
 208                  * of this dentry take up. */
 209                 do {
 210                         *subdir_offset_p += child->length;
 211                         child = child->next;
 212                 } while (child != dentry->children);
 213
 214                 /* End-of-directory dentry on disk. */
 215                 *subdir_offset_p += 8;
 216
 217                 /* Recursively call calculate_subdir_offsets() on all the
 218                  * children. */
 219                 do {
 220                         calculate_subdir_offsets(child, subdir_offset_p);
 221                         child = child->next;
 222                 } while (child != dentry->children);
 223         } else {
 224                 /* On disk, childless directories have a valid subdir_offset
 225                  * that points to an 8-byte end-of-directory dentry.  Regular
 226                  * files have a subdir_offset of 0. */
 227                 if (dentry_is_directory(dentry))
 228                         *subdir_offset_p += 8;
 229                 else
 230                         dentry->subdir_offset = 0;
 231         }
 232 }
 233
 234
 235 /* Returns the child of @dentry that has the file name @name.
 236  * Returns NULL if no child has the name. */
 237 struct dentry *get_dentry_child_with_name(const struct dentry *dentry,
 238                                                         const char *name)
 239 {
 240         struct dentry *child;
 241         size_t name_len;
 242
 243         child = dentry->children;
 244         if (child) {
 245                 name_len = strlen(name);
 246                 do {
 247                         if (dentry_has_name(child, name, name_len))
 248                                 return child;
 249                         child = child->next;
 250                 } while (child != dentry->children);
 251         }
 252         return NULL;
 253 }
 254
 255 /* Retrieves the dentry that has the UTF-8 @path relative to the dentry
 256  * @cur_dir.  Returns NULL if no dentry having the path is found. */
 257 static struct dentry *get_dentry_relative_path(struct dentry *cur_dir, const char *path)
 258 {
 259         struct dentry *child;
 260         size_t base_len;
 261         const char *new_path;
 262
 263         if (*path == '\0')
 264                 return cur_dir;
 265
 266         child = cur_dir->children;
 267         if (child) {
 268                 new_path = path_next_part(path, &base_len);
 269                 do {
 270                         if (dentry_has_name(child, path, base_len))
 271                                 return get_dentry_relative_path(child, new_path);
 272                         child = child->next;
 273                 } while (child != cur_dir->children);
 274         }
 275         return NULL;
 276 }
 277
 278 /* Returns the dentry corresponding to the UTF-8 @path, or NULL if there is no
 279  * such dentry. */
 280 struct dentry *get_dentry(WIMStruct *w, const char *path)
 281 {
 282         struct dentry *root = wim_root_dentry(w);
 283         while (*path == '/')
 284                 path++;
 285         return get_dentry_relative_path(root, path);
 286 }
 287
 288 /* Returns the parent directory for the @path. */
 289 struct dentry *get_parent_dentry(WIMStruct *w, const char *path)
 290 {
 291         size_t path_len = strlen(path);
 292         char buf[path_len + 1];
 293
 294         memcpy(buf, path, path_len + 1);
 295
 296         to_parent_name(buf, path_len);
 297
 298         return get_dentry(w, buf);
 299 }
 300
 301 /* Prints the full path of a dentry. */
 302 int print_dentry_full_path(struct dentry *dentry, void *ignore)
 303 {
 304         if (dentry->full_path_utf8)
 305                 puts(dentry->full_path_utf8);
 306         return 0;
 307 }
 308
 309 /* Prints a directory entry.  @lookup_table is a pointer to the lookup table, or
 310  * NULL if the resource entry for the dentry is not to be printed. */
 311 int print_dentry(struct dentry *dentry, void *lookup_table)
 312 {
 313         struct lookup_table_entry *lte;
 314         printf("[DENTRY]\n");
 315         printf("Length            = %"PRIu64"\n", dentry->length);
 316         printf("Attributes        = 0x%x\n", dentry->attributes);
 317 #ifdef ENABLE_SECURITY_DATA
 318         printf("Security ID       = %d\n", dentry->security_id);
 319 #endif
 320         printf("Subdir offset     = %"PRIu64"\n", dentry->subdir_offset);
 321         /*printf("Unused1           = %"PRIu64"\n", dentry->unused1);*/
 322         /*printf("Unused2           = %"PRIu64"\n", dentry->unused2);*/
 323         printf("Creation Time     = %"PRIu64"\n", dentry->creation_time);
 324         printf("Last Access Time  = %"PRIu64"\n", dentry->last_access_time);
 325         printf("Last Write Time   = %"PRIu64"\n", dentry->last_write_time);
 326         printf("Creation Time     = 0x%"PRIx64"\n", dentry->creation_time);
 327         printf("Hash              = ");
 328         print_hash(dentry->hash);
 329         putchar('\n');
 330         /*printf("Reparse Tag       = %u\n", dentry->reparse_tag);*/
 331         printf("Hard Link Group   = %"PRIu64"\n", dentry->hard_link);
 332         /*printf("Number of Streams = %hu\n", dentry->streams);*/
 333         printf("Filename          = \"");
 334         print_string(dentry->file_name, dentry->file_name_len);
 335         puts("\"");
 336         printf("Filename Length   = %hu\n", dentry->file_name_len);
 337         printf("Filename (UTF-8)  = \"%s\"\n", dentry->file_name_utf8);
 338         printf("Filename (UTF-8) Length = %hu\n", dentry->file_name_utf8_len);
 339         printf("Short Name        = \"");
 340         print_string(dentry->short_name, dentry->short_name_len);
 341         puts("\"");
 342         printf("Short Name Length = %hu\n", dentry->short_name_len);
 343         printf("Full Path (UTF-8) = \"%s\"\n", dentry->full_path_utf8);
 344         if (lookup_table) {
 345                 lte = lookup_resource(lookup_table, dentry->hash);
 346                 if (lte)
 347                         print_lookup_table_entry(lte, NULL);
 348                 else
 349                         putchar('\n');
 350         } else {
 351                 putchar('\n');
 352         }
 353         return 0;
 354 }
 355
 356 static inline void dentry_common_init(struct dentry *dentry)
 357 {
 358         memset(dentry, 0, sizeof(struct dentry));
 359         dentry->refcnt = 1;
 360 #ifdef ENABLE_SECURITY_DATA
 361         dentry->security_id = -1;
 362 #endif
 363 }
 364
 365 /*
 366  * Creates an unlinked directory entry.
 367  *
 368  * @name:    The base name of the new dentry.
 369  * @return:  A pointer to the new dentry, or NULL if out of memory.
 370  */
 371 struct dentry *new_dentry(const char *name)
 372 {
 373         struct dentry *dentry;
 374
 375         dentry = MALLOC(sizeof(struct dentry));
 376         if (!dentry)
 377                 return NULL;
 378
 379         dentry_common_init(dentry);
 380         if (change_dentry_name(dentry, name) != 0) {
 381                 FREE(dentry);
 382                 return NULL;
 383         }
 384
 385         dentry_update_all_timestamps(dentry);
 386         dentry->next   = dentry;
 387         dentry->prev   = dentry;
 388         dentry->parent = dentry;
 389         return dentry;
 390 }
 391
 392
 393 void free_dentry(struct dentry *dentry)
 394 {
 395         FREE(dentry->file_name);
 396         FREE(dentry->file_name_utf8);
 397         FREE(dentry->short_name);
 398         FREE(dentry->full_path_utf8);
 399         FREE(dentry);
 400 }
 401
 402 /* Arguments for do_free_dentry(). */
 403 struct free_dentry_args {
 404         struct lookup_table *lookup_table;
 405         bool decrement_refcnt;
 406 };
 407
 408 /*
 409  * This function is passed as an argument to for_dentry_in_tree_depth() in order
 410  * to free a directory tree.  __args is a pointer to a `struct free_dentry_args'.
 411  */
 412 static int do_free_dentry(struct dentry *dentry, void *__args)
 413 {
 414         struct free_dentry_args *args = (struct free_dentry_args*)__args;
 415
 416         if (args->decrement_refcnt && !dentry_is_directory(dentry)) {
 417                 lookup_table_decrement_refcnt(args->lookup_table,
 418                                               dentry->hash);
 419         }
 420
 421         wimlib_assert(dentry->refcnt >= 1);
 422         if (--dentry->refcnt == 0)
 423                 free_dentry(dentry);
 424         return 0;
 425 }
 426
 427 /*
 428  * Unlinks and frees a dentry tree.
 429  *
 430  * @root:               The root of the tree.
 431  * @lookup_table:       The lookup table for dentries.
 432  * @decrement_refcnt:   True if the dentries in the tree are to have their
 433  *                      reference counts in the lookup table decremented.
 434  */
 435 void free_dentry_tree(struct dentry *root, struct lookup_table *lookup_table,
 436                       bool decrement_refcnt)
 437 {
 438         if (!root || !root->parent)
 439                 return;
 440
 441         struct free_dentry_args args;
 442         args.lookup_table        = lookup_table;
 443         args.decrement_refcnt    = decrement_refcnt;
 444         for_dentry_in_tree_depth(root, do_free_dentry, &args);
 445 }
 446
 447 int increment_dentry_refcnt(struct dentry *dentry, void *ignore)
 448 {
 449         dentry->refcnt++;
 450         return 0;
 451 }
 452
 453 /*
 454  * Links a dentry into the directory tree.
 455  *
 456  * @dentry: The dentry to link.
 457  * @parent: The dentry that will be the parent of @dentry.
 458  */
 459 void link_dentry(struct dentry *dentry, struct dentry *parent)
 460 {
 461         dentry->parent = parent;
 462         if (parent->children) {
 463                 /* Not an only child; link to siblings. */
 464                 dentry->next = parent->children;
 465                 dentry->prev = parent->children->prev;
 466                 dentry->next->prev = dentry;
 467                 dentry->prev->next = dentry;
 468         } else {
 469                 /* Only child; link to parent. */
 470                 parent->children = dentry;
 471                 dentry->next = dentry;
 472                 dentry->prev = dentry;
 473         }
 474 }
 475
 476 /* Unlink a dentry from the directory tree. */
 477 void unlink_dentry(struct dentry *dentry)
 478 {
 479         if (dentry_is_root(dentry))
 480                 return;
 481         if (dentry_is_only_child(dentry)) {
 482                 dentry->parent->children = NULL;
 483         } else {
 484                 if (dentry_is_first_sibling(dentry))
 485                         dentry->parent->children = dentry->next;
 486                 dentry->next->prev = dentry->prev;
 487                 dentry->prev->next = dentry->next;
 488         }
 489 }
 490
 491
 492 /* Recalculates the length of @dentry based on its file name length and short
 493  * name length.  */
 494 static inline void recalculate_dentry_size(struct dentry *dentry)
 495 {
 496         dentry->length = WIM_DENTRY_DISK_SIZE + dentry->file_name_len +
 497                          2 + dentry->short_name_len;
 498         /* Must be multiple of 8. */
 499         dentry->length += (8 - dentry->length % 8) % 8;
 500 }
 501
 502 /* Changes the name of a dentry to @new_name.  Only changes the file_name and
 503  * file_name_utf8 fields; does not change the short_name, short_name_utf8, or
 504  * full_path_utf8 fields.  Also recalculates its length. */
 505 int change_dentry_name(struct dentry *dentry, const char *new_name)
 506 {
 507         size_t utf8_len;
 508         size_t utf16_len;
 509
 510         FREE(dentry->file_name);
 511
 512         utf8_len = strlen(new_name);
 513
 514         dentry->file_name = utf8_to_utf16(new_name, utf8_len, &utf16_len);
 515
 516         if (!dentry->file_name)
 517                 return WIMLIB_ERR_NOMEM;
 518
 519         FREE(dentry->file_name_utf8);
 520         dentry->file_name_utf8 = MALLOC(utf8_len + 1);
 521         if (!dentry->file_name_utf8) {
 522                 FREE(dentry->file_name);
 523                 dentry->file_name = NULL;
 524                 return WIMLIB_ERR_NOMEM;
 525         }
 526
 527         dentry->file_name_len = utf16_len;
 528         dentry->file_name_utf8_len = utf8_len;
 529         memcpy(dentry->file_name_utf8, new_name, utf8_len + 1);
 530         recalculate_dentry_size(dentry);
 531         return 0;
 532 }
 533
 534 /* Parameters for calculate_dentry_statistics(). */
 535 struct image_statistics {
 536         struct lookup_table *lookup_table;
 537         u64 *dir_count;
 538         u64 *file_count;
 539         u64 *total_bytes;
 540         u64 *hard_link_bytes;
 541 };
 542
 543 static int calculate_dentry_statistics(struct dentry *dentry, void *arg)
 544 {
 545         struct image_statistics *stats;
 546         struct lookup_table_entry *lte;
 547
 548         stats = arg;
 549         lte = lookup_resource(stats->lookup_table, dentry->hash);
 550
 551         if (dentry_is_directory(dentry) && !dentry_is_root(dentry))
 552                 ++*stats->dir_count;
 553         else
 554                 ++*stats->file_count;
 555
 556         if (lte) {
 557                 u64 size = lte->resource_entry.original_size;
 558                 *stats->total_bytes += size;
 559                 if (++lte->out_refcnt == 1)
 560                         *stats->hard_link_bytes += size;
 561         }
 562         return 0;
 563 }
 564
 565 void calculate_dir_tree_statistics(struct dentry *root, struct lookup_table *table,
 566                                    u64 *dir_count_ret, u64 *file_count_ret,
 567                                    u64 *total_bytes_ret,
 568                                    u64 *hard_link_bytes_ret)
 569 {
 570         struct image_statistics stats;
 571         *dir_count_ret         = 0;
 572         *file_count_ret        = 0;
 573         *total_bytes_ret       = 0;
 574         *hard_link_bytes_ret   = 0;
 575         stats.lookup_table     = table;
 576         stats.dir_count       = dir_count_ret;
 577         stats.file_count      = file_count_ret;
 578         stats.total_bytes     = total_bytes_ret;
 579         stats.hard_link_bytes = hard_link_bytes_ret;
 580         for_lookup_table_entry(table, zero_out_refcnts, NULL);
 581         for_dentry_in_tree(root, calculate_dentry_statistics, &stats);
 582 }
 583
 584 /*
 585  * Reads a directory entry from the metadata resource.
 586  */
 587 int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
 588                                         u64 offset, struct dentry *dentry)
 589 {
 590         const u8 *p;
 591         u64 calculated_size;
 592         char *file_name;
 593         char *file_name_utf8;
 594         char *short_name;
 595         u16 short_name_len;
 596         u16 file_name_len;
 597         size_t file_name_utf8_len;
 598
 599         dentry_common_init(dentry);
 600
 601         /*Make sure the dentry really fits into the metadata resource.*/
 602         if (offset + 8 > metadata_resource_len) {
 603                 ERROR("Directory entry starting at %"PRIu64" ends past the "
 604                         "end of the metadata resource (size %"PRIu64")!\n",
 605                         offset, metadata_resource_len);
 606                 return WIMLIB_ERR_INVALID_DENTRY;
 607         }
 608
 609         /* Before reading the whole entry, we need to read just the length.
 610          * This is because an entry of length 8 (that is, just the length field)
 611          * terminates the list of sibling directory entries. */
 612
 613         p = get_u64(&metadata_resource[offset], &dentry->length);
 614
 615         /* A zero length field (really a length of 8, since that's how big the
 616          * directory entry is...) indicates that this is the end of directory
 617          * dentry.  We do not read it into memory as an actual dentry, so just
 618          * return true in that case. */
 619         if (dentry->length == 0)
 620                 return 0;
 621
 622         if (offset + dentry->length >= metadata_resource_len) {
 623                 ERROR("Directory entry at offset %"PRIu64" and with size "
 624                                 "%"PRIu64" ends past the end of the metadata resource "
 625                                 "(size %"PRIu64")!\n", offset, dentry->length,
 626                                 metadata_resource_len);
 627                 return WIMLIB_ERR_INVALID_DENTRY;
 628         }
 629
 630         /* If it is a recognized length, read the rest of the directory entry.
 631          * Note: The root directory entry has no name, and its length does not
 632          * include the short name length field.  */
 633         if (dentry->length < WIM_DENTRY_DISK_SIZE) {
 634                 ERROR("Directory entry has invalid length of "
 635                                 "%"PRIu64" bytes\n", dentry->length);
 636                 return WIMLIB_ERR_INVALID_DENTRY;
 637         }
 638
 639         p = get_u32(p, &dentry->attributes);
 640 #ifdef ENABLE_SECURITY_DATA
 641         p = get_u32(p, &dentry->security_id);
 642 #else
 643         p += sizeof(u32);
 644 #endif
 645         p = get_u64(p, &dentry->subdir_offset);
 646
 647         /* 2 unused fields */
 648         p += 2 * sizeof(u64);
 649
 650         p = get_u64(p, &dentry->creation_time);
 651         p = get_u64(p, &dentry->last_access_time);
 652         p = get_u64(p, &dentry->last_write_time);
 653
 654         p = get_bytes(p, WIM_HASH_SIZE, dentry->hash);
 655
 656         /* Currently ignoring reparse_tag. */
 657         p += sizeof(u32);
 658
 659         /* The reparse_reserved field does not actually exist. */
 660
 661         p = get_u64(p, &dentry->hard_link);
 662
 663         /* Currently ignoring streams. */
 664         p += sizeof(u16);
 665
 666         p = get_u16(p, &short_name_len);
 667         p = get_u16(p, &file_name_len);
 668
 669         calculated_size = WIM_DENTRY_DISK_SIZE + file_name_len + 2 +
 670                           short_name_len;
 671
 672         if (dentry->length < calculated_size) {
 673                 ERROR("Unexpected end of directory entry! (Expected "
 674                                 "%"PRIu64" bytes, got %"PRIu64" bytes. "
 675                                 "short_name_len = %hu, file_name_len = %hu)\n",
 676                                 calculated_size, dentry->length,
 677                                 short_name_len, file_name_len);
 678                 return WIMLIB_ERR_INVALID_DENTRY;
 679         }
 680
 681         /* Read the filename. */
 682         file_name = MALLOC(file_name_len);
 683         if (!file_name) {
 684                 ERROR("Failed to allocate %hu bytes for dentry file name!\n",
 685                                 file_name_len);
 686                 return WIMLIB_ERR_NOMEM;
 687         }
 688         p = get_bytes(p, file_name_len, file_name);
 689
 690         /* Convert filename to UTF-8. */
 691         file_name_utf8 = utf16_to_utf8(file_name, file_name_len,
 692                                        &file_name_utf8_len);
 693
 694         if (!file_name_utf8) {
 695                 ERROR("Failed to allocate memory to convert UTF16 "
 696                                 "filename (%hu bytes) to UTF8\n",
 697                                 file_name_len);
 698                 goto err_nomem2;
 699         }
 700
 701         /* Undocumented padding between file name and short name.  This probably
 702          * is supposed to be a terminating NULL character. */
 703         p += 2;
 704
 705         /* Read the short filename. */
 706         short_name = MALLOC(short_name_len);
 707         if (!short_name) {
 708                 ERROR("Failed to allocate %hu bytes for short filename\n",
 709                                 short_name_len);
 710                 goto err_nomem1;
 711         }
 712
 713         get_bytes(p, short_name_len, short_name);
 714
 715         dentry->file_name          = file_name;
 716         dentry->file_name_utf8     = file_name_utf8;
 717         dentry->short_name         = short_name;
 718         dentry->file_name_len      = file_name_len;
 719         dentry->file_name_utf8_len = file_name_utf8_len;
 720         dentry->short_name_len     = short_name_len;
 721         return 0;
 722 err_nomem1:
 723         FREE(dentry->file_name_utf8);
 724 err_nomem2:
 725         FREE(dentry->file_name);
 726         return WIMLIB_ERR_NOMEM;
 727 }
 728
 729 /*
 730  * Writes a dentry to an output buffer.
 731  *
 732  * @dentry:  The dentry structure.
 733  * @p:       The memory location to write the data to.
 734  * @return:  True on success, false on failure.
 735  */
 736 static u8 *write_dentry(const struct dentry *dentry, u8 *p)
 737 {
 738         u8 *orig_p = p;
 739         memset(p, 0, dentry->length);
 740         p = put_u64(p, dentry->length);
 741         p = put_u32(p, dentry->attributes);
 742 #ifdef ENABLE_SECURITY_DATA
 743         p = put_u32(p, dentry->security_id);
 744 #else
 745         p = put_u32(p, (u32)(-1));
 746 #endif
 747         p = put_u64(p, dentry->subdir_offset);
 748         p = put_u64(p, 0); /* unused1 */
 749         p = put_u64(p, 0); /* unused2 */
 750         p = put_u64(p, dentry->creation_time);
 751         p = put_u64(p, dentry->last_access_time);
 752         p = put_u64(p, dentry->last_write_time);
 753         p = put_bytes(p, WIM_HASH_SIZE, dentry->hash);
 754         p = put_u32(p, 0); /* reparse_tag */
 755         p = put_u64(p, dentry->hard_link);
 756         p = put_u16(p, 0); /*streams */
 757         p = put_u16(p, dentry->short_name_len);
 758         p = put_u16(p, dentry->file_name_len);
 759         p = put_bytes(p, dentry->file_name_len, (u8*)dentry->file_name);
 760         p = put_u16(p, 0); /* filename padding, 2 bytes. */
 761         p = put_bytes(p, dentry->short_name_len, (u8*)dentry->short_name);
 762         return orig_p + dentry->length;
 763 }
 764
 765 /* Recursive function that writes a dentry tree rooted at @tree, not including
 766  * @tree itself, which has already been written, except in the case of the root
 767  * dentry, which is written right away, along with an end-of-directory entry. */
 768 u8 *write_dentry_tree(const struct dentry *tree, u8 *p)
 769 {
 770         const struct dentry *child;
 771
 772         if (dentry_is_root(tree)) {
 773                 p = write_dentry(tree, p);
 774
 775                 /* write end of directory entry */
 776                 p = put_u64(p, 0);
 777         } else {
 778                 /* Nothing to do for a regular file. */
 779                 if (dentry_is_regular_file(tree))
 780                         return p;
 781         }
 782
 783         /* Write child dentries and end-of-directory entry. */
 784         child = tree->children;
 785         if (child) {
 786                 do {
 787                         p = write_dentry(child, p);
 788                         child = child->next;
 789                 } while (child != tree->children);
 790         }
 791
 792         /* write end of directory entry */
 793         p = put_u64(p, 0);
 794
 795         /* Recurse on children. */
 796         if (child) {
 797                 do {
 798                         p = write_dentry_tree(child, p);
 799                         child = child->next;
 800                 } while (child != tree->children);
 801         }
 802         return p;
 803 }
 804
 805 /* Reads the children of a dentry, and all their children, ..., etc. from the
 806  * metadata resource and into the dentry tree.
 807  *
 808  * @metadata_resource:  An array that contains the uncompressed metadata
 809  *                              resource for the WIM file.
 810  * @metadata_resource_len:      The length of @metadata_resource.
 811  * @dentry:     A pointer to a struct dentry that is the root of the directory tree
 812  *              and has already been read from the metadata resource.  It does not
 813  *              need to be the real root, because this procedure is called
 814  *              recursively.
 815  * @return:     True on success, false on failure.
 816  */
 817 int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
 818                      struct dentry *dentry)
 819 {
 820         u64 cur_offset = dentry->subdir_offset;
 821         struct dentry *prev_child = NULL;
 822         struct dentry *first_child = NULL;
 823         struct dentry *child;
 824         struct dentry cur_child;
 825         int ret;
 826
 827         /* If @dentry is a regular file, nothing more needs to be done for this
 828          * branch. */
 829         if (cur_offset == 0)
 830                 return 0;
 831
 832         /* Find and read all the children of @dentry. */
 833         while (1) {
 834
 835                 /* Read next child of @dentry into @cur_child. */
 836                 ret = read_dentry(metadata_resource, metadata_resource_len,
 837                                   cur_offset, &cur_child);
 838                 if (ret != 0)
 839                         break;
 840
 841                 /* Check for end of directory. */
 842                 if (cur_child.length == 0) {
 843                         ret = 0;
 844                         break;
 845                 }
 846
 847                 /* Not end of directory.  Allocate this child permanently and
 848                  * link it to the parent and previous child. */
 849                 child = MALLOC(sizeof(struct dentry));
 850                 if (!child) {
 851                         ERROR("Failed to allocate %zu bytes for new dentry!\n",
 852                                         sizeof(struct dentry));
 853                         ret = WIMLIB_ERR_NOMEM;
 854                         break;
 855                 }
 856                 memcpy(child, &cur_child, sizeof(struct dentry));
 857
 858                 if (prev_child) {
 859                         prev_child->next = child;
 860                         child->prev = prev_child;
 861                 } else {
 862                         first_child = child;
 863                 }
 864
 865                 child->parent = dentry;
 866                 prev_child = child;
 867
 868                 /* If there are children of this child, call this procedure
 869                  * recursively. */
 870                 if (child->subdir_offset != 0) {
 871                         ret = read_dentry_tree(metadata_resource,
 872                                                metadata_resource_len, child);
 873                         if (ret != 0)
 874                                 break;
 875                 }
 876
 877                 /* Advance to the offset of the next child. */
 878                 cur_offset += child->length;
 879         }
 880
 881         /* Link last child to first one, and set parent's
 882          * children pointer to the first child.  */
 883         if (prev_child) {
 884                 prev_child->next = first_child;
 885                 first_child->prev = prev_child;
 886         }
 887         dentry->children = first_child;
 888         return ret;
 889 }