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
13 * Copyright (C) 2012 Eric Biggers
15 * This file is part of wimlib, a library for working with WIM files.
17 * wimlib is free software; you can redistribute it and/or modify it under the
18 * terms of the GNU General Public License as published by the Free Software
19 * Foundation; either version 3 of the License, or (at your option) any later
22 * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
23 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
24 * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
26 * You should have received a copy of the GNU General Public License along with
27 * wimlib; if not, see http://www.gnu.org/licenses/.
37 #include "lookup_table.h"
39 #include "timestamp.h"
40 #include "wimlib_internal.h"
43 * Returns true if @dentry has the UTF-8 file name @name that has length
46 static bool dentry_has_name(const struct dentry *dentry, const char *name,
49 if (dentry->file_name_utf8_len != name_len)
51 return memcmp(dentry->file_name_utf8, name, name_len) == 0;
54 static u64 __dentry_correct_length_unaligned(u16 file_name_len,
57 u64 length = WIM_DENTRY_DISK_SIZE;
59 length += file_name_len + 2;
61 length += short_name_len + 2;
65 static u64 dentry_correct_length_unaligned(const struct dentry *dentry)
67 return __dentry_correct_length_unaligned(dentry->file_name_len,
68 dentry->short_name_len);
71 /* Return the "correct" value to write in the length field of the dentry, based
72 * on the file name length and short name length */
73 static u64 dentry_correct_length(const struct dentry *dentry)
75 return (dentry_correct_length_unaligned(dentry) + 7) & ~7;
78 static u64 __dentry_total_length(const struct dentry *dentry, u64 length)
80 const struct inode *inode = dentry->inode;
81 for (u16 i = 0; i < inode->num_ads; i++)
82 length += ads_entry_total_length(inode->ads_entries[i]);
83 return (length + 7) & ~7;
86 u64 dentry_correct_total_length(const struct dentry *dentry)
88 return __dentry_total_length(dentry,
89 dentry_correct_length_unaligned(dentry));
92 /* Real length of a dentry, including the alternate data stream entries, which
93 * are not included in the dentry->length field... */
94 u64 dentry_total_length(const struct dentry *dentry)
96 return __dentry_total_length(dentry, dentry->length);
99 /* Transfers file attributes from a `stat' buffer to an inode. */
100 void stbuf_to_inode(const struct stat *stbuf, struct inode *inode)
102 if (S_ISLNK(stbuf->st_mode)) {
103 inode->attributes = FILE_ATTRIBUTE_REPARSE_POINT;
104 inode->reparse_tag = WIM_IO_REPARSE_TAG_SYMLINK;
105 } else if (S_ISDIR(stbuf->st_mode)) {
106 inode->attributes = FILE_ATTRIBUTE_DIRECTORY;
108 inode->attributes = FILE_ATTRIBUTE_NORMAL;
110 if (sizeof(ino_t) >= 8)
111 inode->ino = (u64)stbuf->st_ino;
113 inode->ino = (u64)stbuf->st_ino |
114 ((u64)stbuf->st_dev << (sizeof(ino_t) * 8));
116 inode->creation_time = timespec_to_wim_timestamp(&stbuf->st_mtim);
117 inode->last_write_time = timespec_to_wim_timestamp(&stbuf->st_mtim);
118 inode->last_access_time = timespec_to_wim_timestamp(&stbuf->st_atim);
122 /* Sets all the timestamp fields of the dentry to the current time. */
123 void inode_update_all_timestamps(struct inode *inode)
125 u64 now = get_wim_timestamp();
126 inode->creation_time = now;
127 inode->last_access_time = now;
128 inode->last_write_time = now;
131 /* Returns the alternate data stream entry belonging to @inode that has the
132 * stream name @stream_name. */
133 struct ads_entry *inode_get_ads_entry(struct inode *inode,
134 const char *stream_name,
137 size_t stream_name_len;
140 if (inode->num_ads) {
142 stream_name_len = strlen(stream_name);
144 if (ads_entry_has_name(inode->ads_entries[i],
145 stream_name, stream_name_len))
149 return inode->ads_entries[i];
151 } while (++i != inode->num_ads);
157 static struct ads_entry *new_ads_entry(const char *name)
159 struct ads_entry *ads_entry = CALLOC(1, sizeof(struct ads_entry));
163 if (change_ads_name(ads_entry, name)) {
172 * Add an alternate stream entry to an inode and return a pointer to it, or NULL
173 * if memory could not be allocated.
175 struct ads_entry *inode_add_ads(struct inode *inode, const char *stream_name)
178 struct ads_entry **ads_entries;
179 struct ads_entry *new_entry;
181 if (inode->num_ads >= 0xfffe) {
182 ERROR("Too many alternate data streams in one inode!");
185 num_ads = inode->num_ads + 1;
186 ads_entries = REALLOC(inode->ads_entries,
187 num_ads * sizeof(inode->ads_entries[0]));
189 ERROR("Failed to allocate memory for new alternate data stream");
192 inode->ads_entries = ads_entries;
194 new_entry = new_ads_entry(stream_name);
197 inode->num_ads = num_ads;
198 ads_entries[num_ads - 1] = new_entry;
204 * Calls a function on all directory entries in a directory tree. It is called
205 * on a parent before its children.
207 int for_dentry_in_tree(struct dentry *root,
208 int (*visitor)(struct dentry*, void*), void *arg)
211 struct dentry *child;
213 ret = visitor(root, arg);
218 child = root->inode->children;
224 ret = for_dentry_in_tree(child, visitor, arg);
228 } while (child != root->inode->children);
233 * Like for_dentry_in_tree(), but the visitor function is always called on a
234 * dentry's children before on itself.
236 int for_dentry_in_tree_depth(struct dentry *root,
237 int (*visitor)(struct dentry*, void*), void *arg)
240 struct dentry *child;
243 child = root->inode->children;
247 ret = for_dentry_in_tree_depth(child, visitor, arg);
251 } while (child != root->inode->children);
253 return visitor(root, arg);
257 * Calculate the full path of @dentry, based on its parent's full path and on
258 * its UTF-8 file name.
260 int calculate_dentry_full_path(struct dentry *dentry, void *ignore)
264 if (dentry_is_root(dentry)) {
265 full_path = MALLOC(2);
272 char *parent_full_path;
273 u32 parent_full_path_len;
274 const struct dentry *parent = dentry->parent;
276 if (dentry_is_root(parent)) {
277 parent_full_path = "";
278 parent_full_path_len = 0;
280 parent_full_path = parent->full_path_utf8;
281 parent_full_path_len = parent->full_path_utf8_len;
284 full_path_len = parent_full_path_len + 1 +
285 dentry->file_name_utf8_len;
286 full_path = MALLOC(full_path_len + 1);
290 memcpy(full_path, parent_full_path, parent_full_path_len);
291 full_path[parent_full_path_len] = '/';
292 memcpy(full_path + parent_full_path_len + 1,
293 dentry->file_name_utf8,
294 dentry->file_name_utf8_len);
295 full_path[full_path_len] = '\0';
297 FREE(dentry->full_path_utf8);
298 dentry->full_path_utf8 = full_path;
299 dentry->full_path_utf8_len = full_path_len;
302 ERROR("Out of memory while calculating dentry full path");
303 return WIMLIB_ERR_NOMEM;
307 * Recursively calculates the subdir offsets for a directory tree.
309 * @dentry: The root of the directory tree.
310 * @subdir_offset_p: The current subdirectory offset; i.e., the subdirectory
311 * offset for @dentry.
313 void calculate_subdir_offsets(struct dentry *dentry, u64 *subdir_offset_p)
315 struct dentry *child;
317 child = dentry->inode->children;
318 dentry->subdir_offset = *subdir_offset_p;
321 /* Advance the subdir offset by the amount of space the children
322 * of this dentry take up. */
324 *subdir_offset_p += dentry_correct_total_length(child);
326 } while (child != dentry->inode->children);
328 /* End-of-directory dentry on disk. */
329 *subdir_offset_p += 8;
331 /* Recursively call calculate_subdir_offsets() on all the
334 calculate_subdir_offsets(child, subdir_offset_p);
336 } while (child != dentry->inode->children);
338 /* On disk, childless directories have a valid subdir_offset
339 * that points to an 8-byte end-of-directory dentry. Regular
340 * files or reparse points have a subdir_offset of 0. */
341 if (dentry_is_directory(dentry))
342 *subdir_offset_p += 8;
344 dentry->subdir_offset = 0;
349 /* Returns the child of @dentry that has the file name @name.
350 * Returns NULL if no child has the name. */
351 struct dentry *get_dentry_child_with_name(const struct dentry *dentry,
354 struct dentry *child;
357 child = dentry->inode->children;
359 name_len = strlen(name);
361 if (dentry_has_name(child, name, name_len))
364 } while (child != dentry->inode->children);
369 /* Retrieves the dentry that has the UTF-8 @path relative to the dentry
370 * @cur_dir. Returns NULL if no dentry having the path is found. */
371 static struct dentry *get_dentry_relative_path(struct dentry *cur_dir,
374 struct dentry *child;
376 const char *new_path;
381 child = cur_dir->inode->children;
383 new_path = path_next_part(path, &base_len);
385 if (dentry_has_name(child, path, base_len))
386 return get_dentry_relative_path(child, new_path);
388 } while (child != cur_dir->inode->children);
393 /* Returns the dentry corresponding to the UTF-8 @path, or NULL if there is no
395 struct dentry *get_dentry(WIMStruct *w, const char *path)
397 struct dentry *root = wim_root_dentry(w);
400 return get_dentry_relative_path(root, path);
403 struct inode *wim_pathname_to_inode(WIMStruct *w, const char *path)
405 struct dentry *dentry;
406 dentry = get_dentry(w, path);
410 return dentry->inode;
413 /* Returns the dentry that corresponds to the parent directory of @path, or NULL
414 * if the dentry is not found. */
415 struct dentry *get_parent_dentry(WIMStruct *w, const char *path)
417 size_t path_len = strlen(path);
418 char buf[path_len + 1];
420 memcpy(buf, path, path_len + 1);
422 to_parent_name(buf, path_len);
424 return get_dentry(w, buf);
427 /* Prints the full path of a dentry. */
428 int print_dentry_full_path(struct dentry *dentry, void *ignore)
430 if (dentry->full_path_utf8)
431 puts(dentry->full_path_utf8);
435 /* We want to be able to show the names of the file attribute flags that are
437 struct file_attr_flag {
441 struct file_attr_flag file_attr_flags[] = {
442 {FILE_ATTRIBUTE_READONLY, "READONLY"},
443 {FILE_ATTRIBUTE_HIDDEN, "HIDDEN"},
444 {FILE_ATTRIBUTE_SYSTEM, "SYSTEM"},
445 {FILE_ATTRIBUTE_DIRECTORY, "DIRECTORY"},
446 {FILE_ATTRIBUTE_ARCHIVE, "ARCHIVE"},
447 {FILE_ATTRIBUTE_DEVICE, "DEVICE"},
448 {FILE_ATTRIBUTE_NORMAL, "NORMAL"},
449 {FILE_ATTRIBUTE_TEMPORARY, "TEMPORARY"},
450 {FILE_ATTRIBUTE_SPARSE_FILE, "SPARSE_FILE"},
451 {FILE_ATTRIBUTE_REPARSE_POINT, "REPARSE_POINT"},
452 {FILE_ATTRIBUTE_COMPRESSED, "COMPRESSED"},
453 {FILE_ATTRIBUTE_OFFLINE, "OFFLINE"},
454 {FILE_ATTRIBUTE_NOT_CONTENT_INDEXED,"NOT_CONTENT_INDEXED"},
455 {FILE_ATTRIBUTE_ENCRYPTED, "ENCRYPTED"},
456 {FILE_ATTRIBUTE_VIRTUAL, "VIRTUAL"},
459 /* Prints a directory entry. @lookup_table is a pointer to the lookup table, if
460 * available. If the dentry is unresolved and the lookup table is NULL, the
461 * lookup table entries will not be printed. Otherwise, they will be. */
462 int print_dentry(struct dentry *dentry, void *lookup_table)
465 struct lookup_table_entry *lte;
466 const struct inode *inode = dentry->inode;
470 printf("[DENTRY]\n");
471 printf("Length = %"PRIu64"\n", dentry->length);
472 printf("Attributes = 0x%x\n", inode->attributes);
473 for (unsigned i = 0; i < ARRAY_LEN(file_attr_flags); i++)
474 if (file_attr_flags[i].flag & inode->attributes)
475 printf(" FILE_ATTRIBUTE_%s is set\n",
476 file_attr_flags[i].name);
477 printf("Security ID = %d\n", inode->security_id);
478 printf("Subdir offset = %"PRIu64"\n", dentry->subdir_offset);
480 /* Translate the timestamps into something readable */
481 time = wim_timestamp_to_unix(inode->creation_time);
482 p = asctime(gmtime(&time));
483 *(strrchr(p, '\n')) = '\0';
484 printf("Creation Time = %s UTC\n", p);
486 time = wim_timestamp_to_unix(inode->last_access_time);
487 p = asctime(gmtime(&time));
488 *(strrchr(p, '\n')) = '\0';
489 printf("Last Access Time = %s UTC\n", p);
491 time = wim_timestamp_to_unix(inode->last_write_time);
492 p = asctime(gmtime(&time));
493 *(strrchr(p, '\n')) = '\0';
494 printf("Last Write Time = %s UTC\n", p);
496 printf("Reparse Tag = 0x%"PRIx32"\n", inode->reparse_tag);
497 printf("Hard Link Group = 0x%"PRIx64"\n", inode->ino);
498 printf("Hard Link Group Size = %"PRIu32"\n", inode->link_count);
499 printf("Number of Alternate Data Streams = %hu\n", inode->num_ads);
500 printf("Filename = \"");
501 print_string(dentry->file_name, dentry->file_name_len);
503 printf("Filename Length = %hu\n", dentry->file_name_len);
504 printf("Filename (UTF-8) = \"%s\"\n", dentry->file_name_utf8);
505 printf("Filename (UTF-8) Length = %hu\n", dentry->file_name_utf8_len);
506 printf("Short Name = \"");
507 print_string(dentry->short_name, dentry->short_name_len);
509 printf("Short Name Length = %hu\n", dentry->short_name_len);
510 printf("Full Path (UTF-8) = \"%s\"\n", dentry->full_path_utf8);
511 lte = inode_stream_lte(dentry->inode, 0, lookup_table);
513 print_lookup_table_entry(lte);
515 hash = inode_stream_hash(inode, 0);
523 for (u16 i = 0; i < inode->num_ads; i++) {
524 printf("[Alternate Stream Entry %u]\n", i);
525 printf("Name = \"%s\"\n", inode->ads_entries[i]->stream_name_utf8);
526 printf("Name Length (UTF-16) = %u\n",
527 inode->ads_entries[i]->stream_name_len);
528 hash = inode_stream_hash(inode, i + 1);
534 print_lookup_table_entry(inode_stream_lte(inode, i + 1,
540 /* Initializations done on every `struct dentry'. */
541 static void dentry_common_init(struct dentry *dentry)
543 memset(dentry, 0, sizeof(struct dentry));
547 struct inode *new_timeless_inode()
549 struct inode *inode = CALLOC(1, sizeof(struct inode));
552 inode->security_id = -1;
553 inode->link_count = 1;
554 INIT_LIST_HEAD(&inode->dentry_list);
558 struct inode *new_inode()
560 struct inode *inode = new_timeless_inode();
563 u64 now = get_wim_timestamp();
564 inode->creation_time = now;
565 inode->last_access_time = now;
566 inode->last_write_time = now;
571 * Creates an unlinked directory entry.
573 * @name: The UTF-8 filename of the new dentry.
575 * Returns a pointer to the new dentry, or NULL if out of memory.
577 struct dentry *new_dentry(const char *name)
579 struct dentry *dentry;
581 dentry = MALLOC(sizeof(struct dentry));
585 dentry_common_init(dentry);
586 if (change_dentry_name(dentry, name) != 0)
589 dentry->next = dentry;
590 dentry->prev = dentry;
591 dentry->parent = dentry;
596 ERROR("Failed to allocate new dentry");
600 struct dentry *new_dentry_with_inode(const char *name)
602 struct dentry *dentry;
603 dentry = new_dentry(name);
605 dentry->inode = new_inode();
607 inode_add_dentry(dentry, dentry->inode);
616 void free_ads_entry(struct ads_entry *entry)
619 FREE(entry->stream_name);
620 FREE(entry->stream_name_utf8);
625 void inode_free_ads_entries(struct inode *inode)
627 if (inode->ads_entries) {
628 for (u16 i = 0; i < inode->num_ads; i++)
629 free_ads_entry(inode->ads_entries[i]);
630 FREE(inode->ads_entries);
634 /* Frees an inode. */
635 void free_inode(struct inode *inode)
638 inode_free_ads_entries(inode);
640 wimlib_assert(inode->num_opened_fds == 0);
647 /* Decrements link count on an inode and frees it if the link count reaches 0.
649 struct inode *put_inode(struct inode *inode)
652 wimlib_assert(inode->link_count);
653 if (--inode->link_count == 0) {
655 if (inode->num_opened_fds == 0)
666 /* Frees a WIM dentry.
668 * The inode is freed only if its link count is decremented to 0.
670 struct inode *free_dentry(struct dentry *dentry)
672 wimlib_assert(dentry);
675 FREE(dentry->file_name);
676 FREE(dentry->file_name_utf8);
677 FREE(dentry->short_name);
678 FREE(dentry->full_path_utf8);
679 inode = put_inode(dentry->inode);
684 void put_dentry(struct dentry *dentry)
686 wimlib_assert(dentry);
687 wimlib_assert(dentry->refcnt);
689 if (--dentry->refcnt == 0)
694 /* Partically clones a dentry.
697 * - memory for file names is not cloned (the pointers are all set to NULL
698 * and the lengths are set to zero)
699 * - next, prev, and children pointers and not touched
701 struct dentry *clone_dentry(struct dentry *old)
703 struct dentry *new = MALLOC(sizeof(struct dentry));
706 memcpy(new, old, sizeof(struct dentry));
707 new->file_name = NULL;
708 new->file_name_len = 0;
709 new->file_name_utf8 = NULL;
710 new->file_name_utf8_len = 0;
711 new->short_name = NULL;
712 new->short_name_len = 0;
718 * This function is passed as an argument to for_dentry_in_tree_depth() in order
719 * to free a directory tree. __args is a pointer to a `struct free_dentry_args'.
721 static int do_free_dentry(struct dentry *dentry, void *__lookup_table)
723 struct lookup_table *lookup_table = __lookup_table;
724 struct lookup_table_entry *lte;
725 struct inode *inode = dentry->inode;
729 wimlib_assert(inode->link_count);
730 for (i = 0; i <= inode->num_ads; i++) {
731 lte = inode_stream_lte(inode, i, lookup_table);
732 lte_decrement_refcnt(lte, lookup_table);
736 wimlib_assert(dentry->refcnt != 0);
737 if (--dentry->refcnt == 0)
743 * Unlinks and frees a dentry tree.
745 * @root: The root of the tree.
746 * @lookup_table: The lookup table for dentries. If non-NULL, the
747 * reference counts in the lookup table for the lookup
748 * table entries corresponding to the dentries will be
751 void free_dentry_tree(struct dentry *root, struct lookup_table *lookup_table)
753 if (!root || !root->parent)
755 for_dentry_in_tree_depth(root, do_free_dentry, lookup_table);
758 int increment_dentry_refcnt(struct dentry *dentry, void *ignore)
765 * Links a dentry into the directory tree.
767 * @dentry: The dentry to link.
768 * @parent: The dentry that will be the parent of @dentry.
770 void link_dentry(struct dentry *dentry, struct dentry *parent)
772 wimlib_assert(dentry_is_directory(parent));
773 dentry->parent = parent;
774 if (parent->inode->children) {
775 /* Not an only child; link to siblings. */
776 dentry->next = parent->inode->children;
777 dentry->prev = parent->inode->children->prev;
778 dentry->next->prev = dentry;
779 dentry->prev->next = dentry;
781 /* Only child; link to parent. */
782 parent->inode->children = dentry;
783 dentry->next = dentry;
784 dentry->prev = dentry;
790 * Unlink a dentry from the directory tree.
792 * Note: This merely removes it from the in-memory tree structure.
794 void unlink_dentry(struct dentry *dentry)
796 if (dentry_is_root(dentry))
798 if (dentry_is_only_child(dentry)) {
799 dentry->parent->inode->children = NULL;
801 if (dentry_is_first_sibling(dentry))
802 dentry->parent->inode->children = dentry->next;
803 dentry->next->prev = dentry->prev;
804 dentry->prev->next = dentry->next;
808 /* Duplicates a UTF-8 name into UTF-8 and UTF-16 strings and returns the strings
809 * and their lengths in the pointer arguments */
810 int get_names(char **name_utf16_ret, char **name_utf8_ret,
811 u16 *name_utf16_len_ret, u16 *name_utf8_len_ret,
816 char *name_utf16, *name_utf8;
818 utf8_len = strlen(name);
820 name_utf16 = utf8_to_utf16(name, utf8_len, &utf16_len);
823 return WIMLIB_ERR_NOMEM;
825 name_utf8 = MALLOC(utf8_len + 1);
828 return WIMLIB_ERR_NOMEM;
830 memcpy(name_utf8, name, utf8_len + 1);
831 FREE(*name_utf8_ret);
832 FREE(*name_utf16_ret);
833 *name_utf8_ret = name_utf8;
834 *name_utf16_ret = name_utf16;
835 *name_utf8_len_ret = utf8_len;
836 *name_utf16_len_ret = utf16_len;
840 /* Changes the name of a dentry to @new_name. Only changes the file_name and
841 * file_name_utf8 fields; does not change the short_name, short_name_utf8, or
842 * full_path_utf8 fields. Also recalculates its length. */
843 int change_dentry_name(struct dentry *dentry, const char *new_name)
847 ret = get_names(&dentry->file_name, &dentry->file_name_utf8,
848 &dentry->file_name_len, &dentry->file_name_utf8_len,
850 FREE(dentry->short_name);
851 dentry->short_name_len = 0;
853 dentry->length = dentry_correct_length(dentry);
858 * Changes the name of an alternate data stream */
859 int change_ads_name(struct ads_entry *entry, const char *new_name)
861 return get_names(&entry->stream_name, &entry->stream_name_utf8,
862 &entry->stream_name_len,
863 &entry->stream_name_utf8_len,
867 /* Parameters for calculate_dentry_statistics(). */
868 struct image_statistics {
869 struct lookup_table *lookup_table;
873 u64 *hard_link_bytes;
876 static int calculate_dentry_statistics(struct dentry *dentry, void *arg)
878 struct image_statistics *stats;
879 struct lookup_table_entry *lte;
883 if (dentry_is_directory(dentry) && !dentry_is_root(dentry))
886 ++*stats->file_count;
888 for (unsigned i = 0; i <= dentry->inode->num_ads; i++) {
889 lte = inode_stream_lte(dentry->inode, i, stats->lookup_table);
891 *stats->total_bytes += wim_resource_size(lte);
892 if (++lte->out_refcnt == 1)
893 *stats->hard_link_bytes += wim_resource_size(lte);
899 /* Calculates some statistics about a dentry tree. */
900 void calculate_dir_tree_statistics(struct dentry *root, struct lookup_table *table,
901 u64 *dir_count_ret, u64 *file_count_ret,
902 u64 *total_bytes_ret,
903 u64 *hard_link_bytes_ret)
905 struct image_statistics stats;
908 *total_bytes_ret = 0;
909 *hard_link_bytes_ret = 0;
910 stats.lookup_table = table;
911 stats.dir_count = dir_count_ret;
912 stats.file_count = file_count_ret;
913 stats.total_bytes = total_bytes_ret;
914 stats.hard_link_bytes = hard_link_bytes_ret;
915 for_lookup_table_entry(table, zero_out_refcnts, NULL);
916 for_dentry_in_tree(root, calculate_dentry_statistics, &stats);
921 * Reads the alternate data stream entries for a dentry.
923 * @p: Pointer to buffer that starts with the first alternate stream entry.
925 * @inode: Inode to load the alternate data streams into.
926 * @inode->num_ads must have been set to the number of
927 * alternate data streams that are expected.
929 * @remaining_size: Number of bytes of data remaining in the buffer pointed
932 * The format of the on-disk alternate stream entries is as follows:
934 * struct ads_entry_on_disk {
935 * u64 length; // Length of the entry, in bytes. This includes
936 * all fields (including the stream name and
937 * null terminator if present, AND the padding!).
938 * u64 reserved; // Seems to be unused
939 * u8 hash[20]; // SHA1 message digest of the uncompressed stream
940 * u16 stream_name_len; // Length of the stream name, in bytes
941 * char stream_name[]; // Stream name in UTF-16LE, @stream_name_len bytes long,
942 * not including null terminator
943 * u16 zero; // UTF-16 null terminator for the stream name, NOT
944 * included in @stream_name_len. Based on what
945 * I've observed from filenames in dentries,
946 * this field should not exist when
947 * (@stream_name_len == 0), but you can't
948 * actually tell because of the padding anyway
949 * (provided that the padding is zeroed, which
950 * it always seems to be).
951 * char padding[]; // Padding to make the size a multiple of 8 bytes.
954 * In addition, the entries are 8-byte aligned.
956 * Return 0 on success or nonzero on failure. On success, inode->ads_entries
957 * is set to an array of `struct ads_entry's of length inode->num_ads. On
958 * failure, @inode is not modified.
960 static int read_ads_entries(const u8 *p, struct inode *inode,
964 struct ads_entry **ads_entries;
967 num_ads = inode->num_ads;
968 ads_entries = CALLOC(num_ads, sizeof(inode->ads_entries[0]));
970 ERROR("Could not allocate memory for %"PRIu16" "
971 "alternate data stream entries", num_ads);
972 return WIMLIB_ERR_NOMEM;
975 for (u16 i = 0; i < num_ads; i++) {
976 struct ads_entry *cur_entry;
978 u64 length_no_padding;
981 const u8 *p_save = p;
983 cur_entry = new_ads_entry(NULL);
985 ret = WIMLIB_ERR_NOMEM;
986 goto out_free_ads_entries;
989 ads_entries[i] = cur_entry;
991 /* Read the base stream entry, excluding the stream name. */
992 if (remaining_size < WIM_ADS_ENTRY_DISK_SIZE) {
993 ERROR("Stream entries go past end of metadata resource");
994 ERROR("(remaining_size = %"PRIu64")", remaining_size);
995 ret = WIMLIB_ERR_INVALID_DENTRY;
996 goto out_free_ads_entries;
999 p = get_u64(p, &length);
1000 p += 8; /* Skip the reserved field */
1001 p = get_bytes(p, SHA1_HASH_SIZE, (u8*)cur_entry->hash);
1002 p = get_u16(p, &cur_entry->stream_name_len);
1004 cur_entry->stream_name = NULL;
1005 cur_entry->stream_name_utf8 = NULL;
1007 /* Length including neither the null terminator nor the padding
1009 length_no_padding = WIM_ADS_ENTRY_DISK_SIZE +
1010 cur_entry->stream_name_len;
1012 /* Length including the null terminator and the padding */
1013 total_length = ((length_no_padding + 2) + 7) & ~7;
1015 wimlib_assert(total_length == ads_entry_total_length(cur_entry));
1017 if (remaining_size < length_no_padding) {
1018 ERROR("Stream entries go past end of metadata resource");
1019 ERROR("(remaining_size = %"PRIu64" bytes, "
1020 "length_no_padding = %"PRIu64" bytes)",
1021 remaining_size, length_no_padding);
1022 ret = WIMLIB_ERR_INVALID_DENTRY;
1023 goto out_free_ads_entries;
1026 /* The @length field in the on-disk ADS entry is expected to be
1027 * equal to @total_length, which includes all of the entry and
1028 * the padding that follows it to align the next ADS entry to an
1029 * 8-byte boundary. However, to be safe, we'll accept the
1030 * length field as long as it's not less than the un-padded
1031 * total length and not more than the padded total length. */
1032 if (length < length_no_padding || length > total_length) {
1033 ERROR("Stream entry has unexpected length "
1034 "field (length field = %"PRIu64", "
1035 "unpadded total length = %"PRIu64", "
1036 "padded total length = %"PRIu64")",
1037 length, length_no_padding, total_length);
1038 ret = WIMLIB_ERR_INVALID_DENTRY;
1039 goto out_free_ads_entries;
1042 if (cur_entry->stream_name_len) {
1043 cur_entry->stream_name = MALLOC(cur_entry->stream_name_len);
1044 if (!cur_entry->stream_name) {
1045 ret = WIMLIB_ERR_NOMEM;
1046 goto out_free_ads_entries;
1048 get_bytes(p, cur_entry->stream_name_len,
1049 (u8*)cur_entry->stream_name);
1050 cur_entry->stream_name_utf8 = utf16_to_utf8(cur_entry->stream_name,
1051 cur_entry->stream_name_len,
1053 cur_entry->stream_name_utf8_len = utf8_len;
1055 if (!cur_entry->stream_name_utf8) {
1056 ret = WIMLIB_ERR_NOMEM;
1057 goto out_free_ads_entries;
1060 /* It's expected that the size of every ADS entry is a multiple
1061 * of 8. However, to be safe, I'm allowing the possibility of
1062 * an ADS entry at the very end of the metadata resource ending
1063 * un-aligned. So although we still need to increment the input
1064 * pointer by @total_length to reach the next ADS entry, it's
1065 * possible that less than @total_length is actually remaining
1066 * in the metadata resource. We should set the remaining size to
1067 * 0 bytes if this happens. */
1068 p = p_save + total_length;
1069 if (remaining_size < total_length)
1072 remaining_size -= total_length;
1074 inode->ads_entries = ads_entries;
1076 out_free_ads_entries:
1077 for (u16 i = 0; i < num_ads; i++)
1078 free_ads_entry(ads_entries[i]);
1084 * Reads a directory entry, including all alternate data stream entries that
1085 * follow it, from the WIM image's metadata resource.
1087 * @metadata_resource: Buffer containing the uncompressed metadata resource.
1088 * @metadata_resource_len: Length of the metadata resource.
1089 * @offset: Offset of this directory entry in the metadata resource.
1090 * @dentry: A `struct dentry' that will be filled in by this function.
1092 * Return 0 on success or nonzero on failure. On failure, @dentry have been
1093 * modified, bu it will be left with no pointers to any allocated buffers.
1094 * On success, the dentry->length field must be examined. If zero, this was a
1095 * special "end of directory" dentry and not a real dentry. If nonzero, this
1096 * was a real dentry.
1098 int read_dentry(const u8 metadata_resource[], u64 metadata_resource_len,
1099 u64 offset, struct dentry *dentry)
1102 u64 calculated_size;
1103 char *file_name = NULL;
1104 char *file_name_utf8 = NULL;
1105 char *short_name = NULL;
1108 size_t file_name_utf8_len = 0;
1110 struct inode *inode = NULL;
1112 dentry_common_init(dentry);
1114 /*Make sure the dentry really fits into the metadata resource.*/
1115 if (offset + 8 > metadata_resource_len || offset + 8 < offset) {
1116 ERROR("Directory entry starting at %"PRIu64" ends past the "
1117 "end of the metadata resource (size %"PRIu64")",
1118 offset, metadata_resource_len);
1119 return WIMLIB_ERR_INVALID_DENTRY;
1122 /* Before reading the whole dentry, we need to read just the length.
1123 * This is because a dentry of length 8 (that is, just the length field)
1124 * terminates the list of sibling directory entries. */
1126 p = get_u64(&metadata_resource[offset], &dentry->length);
1128 /* A zero length field (really a length of 8, since that's how big the
1129 * directory entry is...) indicates that this is the end of directory
1130 * dentry. We do not read it into memory as an actual dentry, so just
1131 * return successfully in that case. */
1132 if (dentry->length == 0)
1135 /* If the dentry does not overflow the metadata resource buffer and is
1136 * not too short, read the rest of it (excluding the alternate data
1137 * streams, but including the file name and short name variable-length
1138 * fields) into memory. */
1139 if (offset + dentry->length >= metadata_resource_len
1140 || offset + dentry->length < offset)
1142 ERROR("Directory entry at offset %"PRIu64" and with size "
1143 "%"PRIu64" ends past the end of the metadata resource "
1145 offset, dentry->length, metadata_resource_len);
1146 return WIMLIB_ERR_INVALID_DENTRY;
1149 if (dentry->length < WIM_DENTRY_DISK_SIZE) {
1150 ERROR("Directory entry has invalid length of %"PRIu64" bytes",
1152 return WIMLIB_ERR_INVALID_DENTRY;
1155 inode = new_timeless_inode();
1157 return WIMLIB_ERR_NOMEM;
1159 p = get_u32(p, &inode->attributes);
1160 p = get_u32(p, (u32*)&inode->security_id);
1161 p = get_u64(p, &dentry->subdir_offset);
1163 /* 2 unused fields */
1164 p += 2 * sizeof(u64);
1165 /*p = get_u64(p, &dentry->unused1);*/
1166 /*p = get_u64(p, &dentry->unused2);*/
1168 p = get_u64(p, &inode->creation_time);
1169 p = get_u64(p, &inode->last_access_time);
1170 p = get_u64(p, &inode->last_write_time);
1172 p = get_bytes(p, SHA1_HASH_SIZE, inode->hash);
1175 * I don't know what's going on here. It seems like M$ screwed up the
1176 * reparse points, then put the fields in the same place and didn't
1177 * document it. The WIM_HDR_FLAG_RP_FIX flag in the WIM header might
1178 * have something to do with this, but it's not documented.
1180 if (inode->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
1183 p = get_u32(p, &inode->reparse_tag);
1186 p = get_u32(p, &inode->reparse_tag);
1187 p = get_u64(p, &inode->ino);
1190 /* By the way, the reparse_reserved field does not actually exist (at
1191 * least when the file is not a reparse point) */
1193 p = get_u16(p, &inode->num_ads);
1195 p = get_u16(p, &short_name_len);
1196 p = get_u16(p, &file_name_len);
1198 /* We now know the length of the file name and short name. Make sure
1199 * the length of the dentry is large enough to actually hold them.
1201 * The calculated length here is unaligned to allow for the possibility
1202 * that the dentry->length names an unaligned length, although this
1203 * would be unexpected. */
1204 calculated_size = __dentry_correct_length_unaligned(file_name_len,
1207 if (dentry->length < calculated_size) {
1208 ERROR("Unexpected end of directory entry! (Expected "
1209 "at least %"PRIu64" bytes, got %"PRIu64" bytes. "
1210 "short_name_len = %hu, file_name_len = %hu)",
1211 calculated_size, dentry->length,
1212 short_name_len, file_name_len);
1213 return WIMLIB_ERR_INVALID_DENTRY;
1216 /* Read the filename if present. Note: if the filename is empty, there
1217 * is no null terminator following it. */
1218 if (file_name_len) {
1219 file_name = MALLOC(file_name_len);
1221 ERROR("Failed to allocate %hu bytes for dentry file name",
1223 return WIMLIB_ERR_NOMEM;
1225 p = get_bytes(p, file_name_len, file_name);
1227 /* Convert filename to UTF-8. */
1228 file_name_utf8 = utf16_to_utf8(file_name, file_name_len,
1229 &file_name_utf8_len);
1231 if (!file_name_utf8) {
1232 ERROR("Failed to allocate memory to convert UTF-16 "
1233 "filename (%hu bytes) to UTF-8", file_name_len);
1234 ret = WIMLIB_ERR_NOMEM;
1235 goto out_free_file_name;
1238 WARNING("Expected two zero bytes following the file name "
1239 "`%s', but found non-zero bytes", file_name_utf8);
1243 /* Align the calculated size */
1244 calculated_size = (calculated_size + 7) & ~7;
1246 if (dentry->length > calculated_size) {
1247 /* Weird; the dentry says it's longer than it should be. Note
1248 * that the length field does NOT include the size of the
1249 * alternate stream entries. */
1251 /* Strangely, some directory entries inexplicably have a little
1252 * over 70 bytes of extra data. The exact amount of data seems
1253 * to be 72 bytes, but it is aligned on the next 8-byte
1254 * boundary. It does NOT seem to be alternate data stream
1255 * entries. Here's an example of the aligned data:
1257 * 01000000 40000000 6c786bba c58ede11 b0bb0026 1870892a b6adb76f
1258 * e63a3e46 8fca8653 0d2effa1 6c786bba c58ede11 b0bb0026 1870892a
1259 * 00000000 00000000 00000000 00000000
1261 * Here's one interpretation of how the data is laid out.
1264 * u32 field1; (always 0x00000001)
1265 * u32 field2; (always 0x40000000)
1266 * u8 data[48]; (???)
1267 * u64 reserved1; (always 0)
1268 * u64 reserved2; (always 0)
1270 DEBUG("Dentry for file or directory `%s' has %zu extra "
1272 file_name_utf8, dentry->length - calculated_size);
1275 /* Read the short filename if present. Note: if there is no short
1276 * filename, there is no null terminator following it. */
1277 if (short_name_len) {
1278 short_name = MALLOC(short_name_len);
1280 ERROR("Failed to allocate %hu bytes for short filename",
1282 ret = WIMLIB_ERR_NOMEM;
1283 goto out_free_file_name_utf8;
1286 p = get_bytes(p, short_name_len, short_name);
1288 WARNING("Expected two zero bytes following the file name "
1289 "`%s', but found non-zero bytes", file_name_utf8);
1294 * Read the alternate data streams, if present. dentry->num_ads tells
1295 * us how many they are, and they will directly follow the dentry
1298 * Note that each alternate data stream entry begins on an 8-byte
1299 * aligned boundary, and the alternate data stream entries are NOT
1300 * included in the dentry->length field for some reason.
1302 if (inode->num_ads != 0) {
1303 if (calculated_size > metadata_resource_len - offset) {
1304 ERROR("Not enough space in metadata resource for "
1305 "alternate stream entries");
1306 ret = WIMLIB_ERR_INVALID_DENTRY;
1307 goto out_free_short_name;
1309 ret = read_ads_entries(&metadata_resource[offset + calculated_size],
1311 metadata_resource_len - offset - calculated_size);
1313 goto out_free_short_name;
1316 /* We've read all the data for this dentry. Set the names and their
1317 * lengths, and we've done. */
1318 dentry->inode = inode;
1319 dentry->file_name = file_name;
1320 dentry->file_name_utf8 = file_name_utf8;
1321 dentry->short_name = short_name;
1322 dentry->file_name_len = file_name_len;
1323 dentry->file_name_utf8_len = file_name_utf8_len;
1324 dentry->short_name_len = short_name_len;
1326 out_free_short_name:
1328 out_free_file_name_utf8:
1329 FREE(file_name_utf8);
1337 /* Run some miscellaneous verifications on a WIM dentry */
1338 int verify_dentry(struct dentry *dentry, void *wim)
1340 const WIMStruct *w = wim;
1341 const struct lookup_table *table = w->lookup_table;
1342 const struct wim_security_data *sd = wim_const_security_data(w);
1343 const struct inode *inode = dentry->inode;
1344 int ret = WIMLIB_ERR_INVALID_DENTRY;
1346 /* Check the security ID */
1347 if (inode->security_id < -1) {
1348 ERROR("Dentry `%s' has an invalid security ID (%d)",
1349 dentry->full_path_utf8, inode->security_id);
1352 if (inode->security_id >= sd->num_entries) {
1353 ERROR("Dentry `%s' has an invalid security ID (%d) "
1354 "(there are only %u entries in the security table)",
1355 dentry->full_path_utf8, inode->security_id,
1360 /* Check that lookup table entries for all the resources exist, except
1361 * if the SHA1 message digest is all 0's, which indicates there is
1362 * intentionally no resource there. */
1363 if (w->hdr.total_parts == 1) {
1364 for (unsigned i = 0; i <= inode->num_ads; i++) {
1365 struct lookup_table_entry *lte;
1367 hash = inode_stream_hash_unresolved(inode, i);
1368 lte = __lookup_resource(table, hash);
1369 if (!lte && !is_zero_hash(hash)) {
1370 ERROR("Could not find lookup table entry for stream "
1371 "%u of dentry `%s'", i, dentry->full_path_utf8);
1377 /* Make sure there is only one un-named stream. */
1378 unsigned num_unnamed_streams = 0;
1379 for (unsigned i = 0; i <= inode->num_ads; i++) {
1381 hash = inode_stream_hash_unresolved(inode, i);
1382 if (!inode_stream_name_len(inode, i) && !is_zero_hash(hash))
1383 num_unnamed_streams++;
1385 if (num_unnamed_streams > 1) {
1386 ERROR("Dentry `%s' has multiple (%u) un-named streams",
1387 dentry->full_path_utf8, num_unnamed_streams);
1391 /* Cannot have a short name but no long name */
1392 if (dentry->short_name_len && !dentry->file_name_len) {
1393 ERROR("Dentry `%s' has a short name but no long name",
1394 dentry->full_path_utf8);
1398 /* Make sure root dentry is unnamed */
1399 if (dentry_is_root(dentry)) {
1400 if (dentry->file_name_len) {
1401 ERROR("The root dentry is named `%s', but it must "
1402 "be unnamed", dentry->file_name_utf8);
1408 /* Check timestamps */
1409 if (inode->last_access_time < inode->creation_time ||
1410 inode->last_write_time < inode->creation_time) {
1411 WARNING("Dentry `%s' was created after it was last accessed or "
1412 "written to", dentry->full_path_utf8);
1422 * Writes a WIM dentry to an output buffer.
1424 * @dentry: The dentry structure.
1425 * @p: The memory location to write the data to.
1426 * @return: Pointer to the byte after the last byte we wrote as part of the
1429 static u8 *write_dentry(const struct dentry *dentry, u8 *p)
1433 const struct inode *inode = dentry->inode;
1435 /* We calculate the correct length of the dentry ourselves because the
1436 * dentry->length field may been set to an unexpected value from when we
1437 * read the dentry in (for example, there may have been unknown data
1438 * appended to the end of the dentry...) */
1439 u64 length = dentry_correct_length(dentry);
1441 p = put_u64(p, length);
1442 p = put_u32(p, inode->attributes);
1443 p = put_u32(p, inode->security_id);
1444 p = put_u64(p, dentry->subdir_offset);
1445 p = put_u64(p, 0); /* unused1 */
1446 p = put_u64(p, 0); /* unused2 */
1447 p = put_u64(p, inode->creation_time);
1448 p = put_u64(p, inode->last_access_time);
1449 p = put_u64(p, inode->last_write_time);
1450 hash = inode_stream_hash(inode, 0);
1451 p = put_bytes(p, SHA1_HASH_SIZE, hash);
1452 if (inode->attributes & FILE_ATTRIBUTE_REPARSE_POINT) {
1453 p = put_zeroes(p, 4);
1454 p = put_u32(p, inode->reparse_tag);
1455 p = put_zeroes(p, 4);
1459 if (inode->link_count == 1)
1462 link_group_id = inode->ino;
1463 p = put_u64(p, link_group_id);
1465 p = put_u16(p, inode->num_ads);
1466 p = put_u16(p, dentry->short_name_len);
1467 p = put_u16(p, dentry->file_name_len);
1468 if (dentry->file_name_len) {
1469 p = put_bytes(p, dentry->file_name_len, (u8*)dentry->file_name);
1470 p = put_u16(p, 0); /* filename padding, 2 bytes. */
1472 if (dentry->short_name) {
1473 p = put_bytes(p, dentry->short_name_len, (u8*)dentry->short_name);
1474 p = put_u16(p, 0); /* short name padding, 2 bytes */
1477 /* Align to 8-byte boundary */
1478 wimlib_assert(length >= (p - orig_p)
1479 && length - (p - orig_p) <= 7);
1480 p = put_zeroes(p, length - (p - orig_p));
1482 /* Write the alternate data streams, if there are any. Please see
1483 * read_ads_entries() for comments about the format of the on-disk
1484 * alternate data stream entries. */
1485 for (u16 i = 0; i < inode->num_ads; i++) {
1486 p = put_u64(p, ads_entry_total_length(inode->ads_entries[i]));
1487 p = put_u64(p, 0); /* Unused */
1488 hash = inode_stream_hash(inode, i + 1);
1489 p = put_bytes(p, SHA1_HASH_SIZE, hash);
1490 p = put_u16(p, inode->ads_entries[i]->stream_name_len);
1491 if (inode->ads_entries[i]->stream_name_len) {
1492 p = put_bytes(p, inode->ads_entries[i]->stream_name_len,
1493 (u8*)inode->ads_entries[i]->stream_name);
1496 p = put_zeroes(p, (8 - (p - orig_p) % 8) % 8);
1498 #ifdef ENABLE_ASSERTIONS
1499 wimlib_assert(p - orig_p == __dentry_total_length(dentry, length));
1504 /* Recursive function that writes a dentry tree rooted at @parent, not including
1505 * @parent itself, which has already been written. */
1506 static u8 *write_dentry_tree_recursive(const struct dentry *parent, u8 *p)
1508 const struct dentry *child;
1510 /* Nothing to do if this dentry has no children. */
1511 if (parent->subdir_offset == 0)
1514 /* Write child dentries and end-of-directory entry.
1516 * Note: we need to write all of this dentry's children before
1517 * recursively writing the directory trees rooted at each of the child
1518 * dentries, since the on-disk dentries for a dentry's children are
1519 * always located at consecutive positions in the metadata resource! */
1520 child = parent->inode->children;
1523 p = write_dentry(child, p);
1524 child = child->next;
1525 } while (child != parent->inode->children);
1528 /* write end of directory entry */
1531 /* Recurse on children. */
1534 p = write_dentry_tree_recursive(child, p);
1535 child = child->next;
1536 } while (child != parent->inode->children);
1541 /* Writes a directory tree to the metadata resource.
1543 * @root: Root of the dentry tree.
1544 * @p: Pointer to a buffer with enough space for the dentry tree.
1546 * Returns pointer to the byte after the last byte we wrote.
1548 u8 *write_dentry_tree(const struct dentry *root, u8 *p)
1550 wimlib_assert(dentry_is_root(root));
1552 /* If we're the root dentry, we have no parent that already
1553 * wrote us, so we need to write ourselves. */
1554 p = write_dentry(root, p);
1556 /* Write end of directory entry after the root dentry just to be safe;
1557 * however the root dentry obviously cannot have any siblings. */
1560 /* Recursively write the rest of the dentry tree. */
1561 return write_dentry_tree_recursive(root, p);
1564 /* Reads the children of a dentry, and all their children, ..., etc. from the
1565 * metadata resource and into the dentry tree.
1567 * @metadata_resource: An array that contains the uncompressed metadata
1568 * resource for the WIM file.
1570 * @metadata_resource_len: The length of the uncompressed metadata resource, in
1573 * @dentry: A pointer to a `struct dentry' that is the root of the directory
1574 * tree and has already been read from the metadata resource. It
1575 * does not need to be the real root because this procedure is
1576 * called recursively.
1578 * @return: Zero on success, nonzero on failure.
1580 int read_dentry_tree(const u8 metadata_resource[], u64 metadata_resource_len,
1581 struct dentry *dentry)
1583 u64 cur_offset = dentry->subdir_offset;
1584 struct dentry *prev_child = NULL;
1585 struct dentry *first_child = NULL;
1586 struct dentry *child;
1587 struct dentry cur_child;
1591 * If @dentry has no child dentries, nothing more needs to be done for
1592 * this branch. This is the case for regular files, symbolic links, and
1593 * *possibly* empty directories (although an empty directory may also
1594 * have one child dentry that is the special end-of-directory dentry)
1596 if (cur_offset == 0)
1599 /* Find and read all the children of @dentry. */
1602 /* Read next child of @dentry into @cur_child. */
1603 ret = read_dentry(metadata_resource, metadata_resource_len,
1604 cur_offset, &cur_child);
1608 /* Check for end of directory. */
1609 if (cur_child.length == 0)
1612 /* Not end of directory. Allocate this child permanently and
1613 * link it to the parent and previous child. */
1614 child = MALLOC(sizeof(struct dentry));
1616 ERROR("Failed to allocate %zu bytes for new dentry",
1617 sizeof(struct dentry));
1618 ret = WIMLIB_ERR_NOMEM;
1621 memcpy(child, &cur_child, sizeof(struct dentry));
1624 prev_child->next = child;
1625 child->prev = prev_child;
1627 first_child = child;
1630 child->parent = dentry;
1632 list_add(&child->inode_dentry_list, &child->inode->dentry_list);
1634 /* If there are children of this child, call this procedure
1636 if (child->subdir_offset != 0) {
1637 ret = read_dentry_tree(metadata_resource,
1638 metadata_resource_len, child);
1643 /* Advance to the offset of the next child. Note: We need to
1644 * advance by the TOTAL length of the dentry, not by the length
1645 * child->length, which although it does take into account the
1646 * padding, it DOES NOT take into account alternate stream
1648 cur_offset += dentry_total_length(child);
1651 /* Link last child to first one, and set parent's children pointer to
1652 * the first child. */
1654 prev_child->next = first_child;
1655 first_child->prev = prev_child;
1657 dentry->inode->children = first_child;