Various minor changes and fixes.
[wimlib] / 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 "wimlib_internal.h"
34 #include "dentry.h"
35 #include "io.h"
36 #include "timestamp.h"
37 #include "lookup_table.h"
38 #include "sha1.h"
39 #include <unistd.h>
40 #include <sys/stat.h>
41
42
43 /* Transfers file attributes from a `stat' buffer to a struct dentry. */
44 void stbuf_to_dentry(const struct stat *stbuf, struct dentry *dentry)
45 {
46         if (S_ISDIR(stbuf->st_mode))
47                 dentry->attributes = WIM_FILE_ATTRIBUTE_DIRECTORY;
48         else
49                 dentry->attributes = WIM_FILE_ATTRIBUTE_NORMAL;
50 }
51
52 /* Transfers file attributes from a struct dentry to a `stat' buffer. */
53 void dentry_to_stbuf(const struct dentry *dentry, struct stat *stbuf, 
54                      const struct lookup_table *table)
55 {
56         struct lookup_table_entry *lte;
57
58         if (dentry_is_directory(dentry))
59                 stbuf->st_mode = S_IFDIR | 0755;
60         else
61                 stbuf->st_mode = S_IFREG | 0644;
62
63         if (table)
64                 lte = lookup_resource(table, dentry->hash);
65         else
66                 lte = NULL;
67
68         if (lte) {
69                 stbuf->st_nlink = lte->refcnt;
70                 stbuf->st_size = lte->resource_entry.original_size;
71         } else {
72                 stbuf->st_nlink = 1;
73                 stbuf->st_size = 0;
74         }
75         stbuf->st_uid     = getuid();
76         stbuf->st_gid     = getgid();
77         stbuf->st_atime   = ms_timestamp_to_unix(dentry->last_access_time);
78         stbuf->st_mtime   = ms_timestamp_to_unix(dentry->last_write_time);
79         stbuf->st_ctime   = ms_timestamp_to_unix(dentry->creation_time);
80         stbuf->st_blocks  = (stbuf->st_size + 511) / 512;
81 }
82
83 /* Makes all timestamp fields for the dentry be the current time. */
84 void dentry_update_all_timestamps(struct dentry *dentry)
85 {
86         u64 now = get_timestamp();
87         dentry->creation_time    = now;
88         dentry->last_access_time = now;
89         dentry->last_write_time  = now;
90 }
91
92 /* 
93  * Calls a function on all directory entries in a directory tree.  It is called
94  * on a parent before its children.
95  */
96 int for_dentry_in_tree(struct dentry *root, 
97                        int (*visitor)(struct dentry*, void*), void *arg)
98 {
99         int ret;
100         struct dentry *child;
101
102         ret = visitor(root, arg);
103
104         if (ret != 0)
105                 return ret;
106
107         child = root->children;
108
109         if (!child)
110                 return 0;
111
112         do {
113                 ret = for_dentry_in_tree(child, visitor, arg);
114                 if (ret != 0)
115                         return ret;
116                 child = child->next;
117         } while (child != root->children);
118         return 0;
119 }
120
121 /* 
122  * Like for_dentry_in_tree(), but the visitor function is always called on a
123  * dentry's children before on itself.
124  */
125 int for_dentry_in_tree_depth(struct dentry *root, 
126                              int (*visitor)(struct dentry*, void*), void *arg)
127 {
128         int ret;
129         struct dentry *child;
130         struct dentry *next;
131
132         child = root->children;
133         if (child) {
134                 do {
135                         next = child->next;
136                         ret = for_dentry_in_tree_depth(child, visitor, arg);
137                         if (ret != 0)
138                                 return ret;
139                         child = next;
140                 } while (child != root->children);
141         }
142         return visitor(root, arg);
143 }
144
145 /* 
146  * Calculate the full path of @dentry, based on its parent's full path and on
147  * its UTF-8 file name. 
148  */
149 int calculate_dentry_full_path(struct dentry *dentry, void *ignore)
150 {
151         char *full_path;
152         u32 full_path_len;
153         if (dentry_is_root(dentry)) {
154                 full_path = MALLOC(2);
155                 if (!full_path)
156                         goto oom;
157                 full_path[0] = '/';
158                 full_path[1] = '\0';
159                 full_path_len = 1;
160         } else {
161                 char *parent_full_path;
162                 u32 parent_full_path_len;
163                 const struct dentry *parent = dentry->parent;
164
165                 if (dentry_is_root(parent)) {
166                         parent_full_path = "";
167                         parent_full_path_len = 0;
168                 } else {
169                         parent_full_path = parent->full_path_utf8;
170                         parent_full_path_len = parent->full_path_utf8_len;
171                 }
172
173                 full_path_len = parent_full_path_len + 1 +
174                                 dentry->file_name_utf8_len;
175                 full_path = MALLOC(full_path_len + 1);
176                 if (!full_path)
177                         goto oom;
178
179                 memcpy(full_path, parent_full_path, parent_full_path_len);
180                 full_path[parent_full_path_len] = '/';
181                 memcpy(full_path + parent_full_path_len + 1,
182                        dentry->file_name_utf8,
183                        dentry->file_name_utf8_len);
184                 full_path[full_path_len] = '\0';
185         }
186         FREE(dentry->full_path_utf8);
187         dentry->full_path_utf8 = full_path;
188         dentry->full_path_utf8_len = full_path_len;
189         return 0;
190 oom:
191         ERROR("Out of memory while calculating dentry full path");
192         return WIMLIB_ERR_NOMEM;
193 }
194
195 /* 
196  * Recursively calculates the subdir offsets for a directory tree. 
197  *
198  * @dentry:  The root of the directory tree.
199  * @subdir_offset_p:  The current subdirectory offset; i.e., the subdirectory
200  *      offset for @dentry. 
201  */
202 void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
203 {
204         struct dentry *child;
205
206         child = dentry->children;
207         dentry->subdir_offset = *subdir_offset_p;
208         if (child) {
209
210                 /* Advance the subdir offset by the amount of space the children
211                  * of this dentry take up. */
212                 do {
213                         *subdir_offset_p += child->length;
214                         child = child->next;
215                 } while (child != dentry->children);
216
217                 /* End-of-directory dentry on disk. */
218                 *subdir_offset_p += 8;
219
220                 /* Recursively call calculate_subdir_offsets() on all the
221                  * children. */
222                 do {
223                         calculate_subdir_offsets(child, subdir_offset_p);
224                         child = child->next;
225                 } while (child != dentry->children);
226         } else {
227                 /* On disk, childless directories have a valid subdir_offset
228                  * that points to an 8-byte end-of-directory dentry.  Regular
229                  * files have a subdir_offset of 0. */
230                 if (dentry_is_directory(dentry))
231                         *subdir_offset_p += 8;
232                 else
233                         dentry->subdir_offset = 0;
234         }
235 }
236
237
238 /* Returns the child of @dentry that has the file name @name.  
239  * Returns NULL if no child has the name. */
240 struct dentry *get_dentry_child_with_name(const struct dentry *dentry, 
241                                                         const char *name)
242 {
243         struct dentry *child;
244         size_t name_len;
245         
246         child = dentry->children;
247         if (child) {
248                 name_len = strlen(name);
249                 do {
250                         if (dentry_has_name(child, name, name_len))
251                                 return child;
252                         child = child->next;
253                 } while (child != dentry->children);
254         }
255         return NULL;
256 }
257
258 /* Retrieves the dentry that has the UTF-8 @path relative to the dentry
259  * @cur_dir.  Returns NULL if no dentry having the path is found. */
260 static struct dentry *get_dentry_relative_path(struct dentry *cur_dir, const char *path)
261 {
262         struct dentry *child;
263         size_t base_len;
264         const char *new_path;
265
266         if (*path == '\0')
267                 return cur_dir;
268
269         child = cur_dir->children;
270         if (child) {
271                 new_path = path_next_part(path, &base_len);
272                 do {
273                         if (dentry_has_name(child, path, base_len))
274                                 return get_dentry_relative_path(child, new_path);
275                         child = child->next;
276                 } while (child != cur_dir->children);
277         }
278         return NULL;
279 }
280
281 /* Returns the dentry corresponding to the UTF-8 @path, or NULL if there is no
282  * such dentry. */
283 struct dentry *get_dentry(WIMStruct *w, const char *path)
284 {
285         struct dentry *root = wim_root_dentry(w);
286         while (*path == '/')
287                 path++;
288         return get_dentry_relative_path(root, path);
289 }
290
291 /* Returns the parent directory for the @path. */
292 struct dentry *get_parent_dentry(WIMStruct *w, const char *path)
293 {
294         size_t path_len = strlen(path);
295         char buf[path_len + 1];
296
297         memcpy(buf, path, path_len + 1);
298
299         to_parent_name(buf, path_len);
300
301         return get_dentry(w, buf);
302 }
303
304 /* Prints the full path of a dentry. */
305 int print_dentry_full_path(struct dentry *dentry, void *ignore)
306 {
307         if (dentry->full_path_utf8)
308                 puts(dentry->full_path_utf8);
309         return 0;
310 }
311
312 /* Prints a directory entry.  @lookup_table is a pointer to the lookup table, or
313  * NULL if the resource entry for the dentry is not to be printed. */
314 int print_dentry(struct dentry *dentry, void *lookup_table)
315 {
316         struct lookup_table_entry *lte;
317         printf("[DENTRY]\n");
318         printf("Length            = %"PRIu64"\n", dentry->length);
319         printf("Attributes        = 0x%x\n", dentry->attributes);
320 #ifdef ENABLE_SECURITY_DATA
321         printf("Security ID       = %d\n", dentry->security_id);
322 #endif
323         printf("Subdir offset     = %"PRIu64"\n", dentry->subdir_offset);
324         /*printf("Unused1           = %"PRIu64"\n", dentry->unused1);*/
325         /*printf("Unused2           = %"PRIu64"\n", dentry->unused2);*/
326         printf("Creation Time     = %"PRIu64"\n", dentry->creation_time);
327         printf("Last Access Time  = %"PRIu64"\n", dentry->last_access_time);
328         printf("Last Write Time   = %"PRIu64"\n", dentry->last_write_time);
329         printf("Creation Time     = 0x%"PRIx64"\n", dentry->creation_time);
330         printf("Hash              = "); 
331         print_hash(dentry->hash); 
332         putchar('\n');
333         /*printf("Reparse Tag       = %u\n", dentry->reparse_tag);*/
334         printf("Hard Link Group   = %"PRIu64"\n", dentry->hard_link);
335         /*printf("Number of Streams = %hu\n", dentry->streams);*/
336         printf("Filename          = \"");
337         print_string(dentry->file_name, dentry->file_name_len);
338         puts("\"");
339         printf("Filename Length   = %hu\n", dentry->file_name_len);
340         printf("Filename (UTF-8)  = \"%s\"\n", dentry->file_name_utf8);
341         printf("Filename (UTF-8) Length = %hu\n", dentry->file_name_utf8_len);
342         printf("Short Name        = \"");
343         print_string(dentry->short_name, dentry->short_name_len);
344         puts("\"");
345         printf("Short Name Length = %hu\n", dentry->short_name_len);
346         printf("Full Path (UTF-8) = \"%s\"\n", dentry->full_path_utf8);
347         if (lookup_table) {
348                 lte = lookup_resource(lookup_table, dentry->hash);
349                 if (lte)
350                         print_lookup_table_entry(lte, NULL);
351                 else
352                         putchar('\n');
353         } else {
354                 putchar('\n');
355         }
356         return 0;
357 }
358
359 static inline void dentry_common_init(struct dentry *dentry)
360 {
361         memset(dentry, 0, sizeof(struct dentry));
362         dentry->refcnt = 1;
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 lt_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->lt_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 lt_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.lt_decrement_refcnt = lt_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")",
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")",
626                       offset, dentry->length, 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 %"PRIu64" bytes",
635                       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, (u32*)&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)", 
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",
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 UTF-16 "
696                       "filename (%hu bytes) to UTF-8", file_name_len);
697                 goto out_free_file_name;
698         }
699
700         /* Undocumented padding between file name and short name.  This probably
701          * is supposed to be a terminating null character. */
702         p += 2;
703
704         /* Read the short filename. */
705         short_name = MALLOC(short_name_len);
706         if (!short_name) {
707                 ERROR("Failed to allocate %hu bytes for short filename",
708                       short_name_len);
709                 goto out_free_file_name_utf8;
710         }
711
712         get_bytes(p, short_name_len, short_name);
713
714         dentry->file_name          = file_name;
715         dentry->file_name_utf8     = file_name_utf8;
716         dentry->short_name         = short_name;
717         dentry->file_name_len      = file_name_len;
718         dentry->file_name_utf8_len = file_name_utf8_len;
719         dentry->short_name_len     = short_name_len;
720         return 0;
721 out_free_file_name_utf8:
722         FREE(dentry->file_name_utf8);
723 out_free_file_name:
724         FREE(dentry->file_name);
725         return WIMLIB_ERR_NOMEM;
726 }
727
728 /* 
729  * Writes a dentry to an output buffer.
730  *
731  * @dentry:  The dentry structure.
732  * @p:       The memory location to write the data to.
733  * @return:  True on success, false on failure.
734  */
735 static u8 *write_dentry(const struct dentry *dentry, u8 *p)
736 {
737         u8 *orig_p = p;
738         memset(p, 0, dentry->length);
739         p = put_u64(p, dentry->length);
740         p = put_u32(p, dentry->attributes);
741 #ifdef ENABLE_SECURITY_DATA
742         p = put_u32(p, dentry->security_id);
743 #else
744         p = put_u32(p, (u32)(-1));
745 #endif
746         p = put_u64(p, dentry->subdir_offset);
747         p = put_u64(p, 0); /* unused1 */
748         p = put_u64(p, 0); /* unused2 */
749         p = put_u64(p, dentry->creation_time);
750         p = put_u64(p, dentry->last_access_time);
751         p = put_u64(p, dentry->last_write_time);
752         if (!is_empty_file_hash(dentry->hash))
753                 memcpy(p, dentry->hash, WIM_HASH_SIZE);
754         else
755                 DEBUG("zero hash for %s\n", dentry->file_name_utf8);
756         p += WIM_HASH_SIZE;
757         p = put_u32(p, 0); /* reparse_tag */
758         p = put_u64(p, dentry->hard_link);
759         p = put_u16(p, 0); /*streams */
760         p = put_u16(p, dentry->short_name_len);
761         p = put_u16(p, dentry->file_name_len);
762         p = put_bytes(p, dentry->file_name_len, (u8*)dentry->file_name);
763         p = put_u16(p, 0); /* filename padding, 2 bytes. */
764         p = put_bytes(p, dentry->short_name_len, (u8*)dentry->short_name);
765         return orig_p + dentry->length;
766 }
767
768 /* Recursive function that writes a dentry tree rooted at @tree, not including
769  * @tree itself, which has already been written, except in the case of the root
770  * dentry, which is written right away, along with an end-of-directory entry. */
771 u8 *write_dentry_tree(const struct dentry *tree, u8 *p)
772 {
773         const struct dentry *child;
774
775         if (dentry_is_root(tree)) {
776                 p = write_dentry(tree, p);
777
778                 /* write end of directory entry */
779                 p = put_u64(p, 0);
780         } else {
781                 /* Nothing to do for a regular file. */
782                 if (dentry_is_regular_file(tree))
783                         return p;
784         }
785
786         /* Write child dentries and end-of-directory entry. */
787         child = tree->children;
788         if (child) {
789                 do {
790                         p = write_dentry(child, p);
791                         child = child->next;
792                 } while (child != tree->children);
793         }
794
795         /* write end of directory entry */
796         p = put_u64(p, 0);
797
798         /* Recurse on children. */
799         if (child) {
800                 do {
801                         p = write_dentry_tree(child, p);
802                         child = child->next;
803                 } while (child != tree->children);
804         }
805         return p;
806 }
807
808 /* Reads the children of a dentry, and all their children, ..., etc. from the
809  * metadata resource and into the dentry tree.
810  *
811  * @metadata_resource:  An array that contains the uncompressed metadata
812  *                      resource for the WIM file.
813  * @metadata_resource_len:      The length of @metadata_resource.
814  * @dentry:     A pointer to a struct dentry that is the root of the directory
815  *              tree and has already been read from the metadata resource.  It
816  *              does not need to be the real root because this procedure is
817  *              called recursively.
818  *
819  * @return:     Zero on success, nonzero on failure.
820  */
821 int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
822                      struct dentry *dentry)
823 {
824         u64 cur_offset = dentry->subdir_offset;
825         struct dentry *prev_child = NULL;
826         struct dentry *first_child = NULL;
827         struct dentry *child;
828         struct dentry cur_child;
829         int ret;
830
831         /* If @dentry is a regular file, nothing more needs to be done for this
832          * branch. */
833         if (cur_offset == 0)
834                 return 0;
835
836         /* Find and read all the children of @dentry. */
837         while (1) {
838
839                 /* Read next child of @dentry into @cur_child. */
840                 ret = read_dentry(metadata_resource, metadata_resource_len, 
841                                   cur_offset, &cur_child);
842                 if (ret != 0)
843                         break;
844
845                 /* Check for end of directory. */
846                 if (cur_child.length == 0) {
847                         ret = 0;
848                         break;
849                 }
850
851                 /* Not end of directory.  Allocate this child permanently and
852                  * link it to the parent and previous child. */
853                 child = MALLOC(sizeof(struct dentry));
854                 if (!child) {
855                         ERROR("Failed to allocate %zu bytes for new dentry",
856                               sizeof(struct dentry));
857                         ret = WIMLIB_ERR_NOMEM;
858                         break;
859                 }
860                 memcpy(child, &cur_child, sizeof(struct dentry));
861
862                 if (prev_child) {
863                         prev_child->next = child;
864                         child->prev = prev_child;
865                 } else {
866                         first_child = child;
867                 }
868
869                 child->parent = dentry;
870                 prev_child = child;
871
872                 /* If there are children of this child, call this procedure
873                  * recursively. */
874                 if (child->subdir_offset != 0) {
875                         ret = read_dentry_tree(metadata_resource, 
876                                                metadata_resource_len, child);
877                         if (ret != 0)
878                                 break;
879                 }
880
881                 /* Advance to the offset of the next child. */
882                 cur_offset += child->length;
883         }
884
885         /* Link last child to first one, and set parent's
886          * children pointer to the first child.  */
887         if (prev_child) {
888                 prev_child->next = first_child;
889                 first_child->prev = prev_child;
890         }
891         dentry->children = first_child;
892         return ret;
893 }