+/*
+ * hardlink.c
+ *
+ * Code to deal with hard links in WIMs. Essentially, the WIM dentries are put
+ * into a hash table indexed by the hard link group ID field, then for each hard
+ * link group, a linked list is made to connect the dentries.
+ */
+
+/*
+ * Copyright (C) 2012 Eric Biggers
+ *
+ * This file is part of wimlib, a library for working with WIM files.
+ *
+ * wimlib is free software; you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at your option)
+ * any later version.
+ *
+ * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with wimlib; if not, see http://www.gnu.org/licenses/.
+ */
+
#include "wimlib_internal.h"
#include "dentry.h"
#include "list.h"
#include "lookup_table.h"
+/* NULL NULL
+ * ^ ^
+ * dentry | |
+ * / \ ----------- -----------
+ * | dentry<---| struct | | struct |---> dentry
+ * \ / |link_group| |link_group|
+ * dentry ------------ ------------
+ * ^ ^
+ * | |
+ * | | dentry
+ * ----------- ----------- / \
+ * dentry<---| struct | | struct |---> dentry dentry
+ * / |link_group| |link_group| \ /
+ * dentry ------------ ------------ dentry
+ * ^ ^
+ * | |
+ * -----------------
+ * link_group_table->array | idx 0 | idx 1 |
+ * -----------------
+ */
+
+/* Hard link group; it's identified by its hard link group ID and points to a
+ * circularly linked list of dentries. */
struct link_group {
u64 link_group_id;
+
+ /* Pointer to use to make a singly-linked list of link groups. */
struct link_group *next;
- struct list_head dentry_list;
+
+ /* This is a pointer to the circle and not part of the circle itself.
+ * This makes it easy to iterate through other dentries hard-linked to a
+ * given dentry without having to find the "head" of the list first. */
+ struct list_head *dentry_list;
};
+/* Hash table to find hard link groups, identified by their hard link group ID.
+ * */
struct link_group_table {
+ /* Fields for the hash table */
struct link_group **array;
u64 num_entries;
u64 capacity;
-};
-#include <sys/mman.h>
+ /*
+ * Linked list of "extra" groups. These may be:
+ *
+ * - Hard link groups of size 1, which are all allowed to have 0 for
+ * their hard link group ID, meaning we cannot insert them into the
+ * hash table before calling assign_link_group_ids().
+ *
+ * - Groups we create ourselves by splitting a nominal hard link group
+ * due to inconsistencies in the dentries. These groups will share a
+ * hard link group ID with some other group until
+ * assign_link_group_ids() is called.
+ */
+ struct link_group *extra_groups;
+};
-struct link_group_table *new_link_group_table(u64 capacity)
+/* Returns pointer to a new link group table having the specified capacity */
+struct link_group_table *new_link_group_table(size_t capacity)
{
- return (struct link_group_table*)new_lookup_table(capacity);
+ struct link_group_table *table;
+ struct link_group **array;
+
+ table = MALLOC(sizeof(struct link_group_table));
+ if (!table)
+ goto err;
+ array = CALLOC(capacity, sizeof(array[0]));
+ if (!array) {
+ FREE(table);
+ goto err;
+ }
+ table->num_entries = 0;
+ table->capacity = capacity;
+ table->array = array;
+ table->extra_groups = NULL;
+ return table;
+err:
+ ERROR("Failed to allocate memory for link group table with capacity %zu",
+ capacity);
+ return NULL;
}
-/* Insert a dentry into the hard link group table based on its hard link group
+/*
+ * Insert a dentry into the hard link group table based on its hard link group
* ID.
*
* If there is already a dentry in the table having the same hard link group ID,
- * we link the dentries together in a circular list.
+ * and the hard link group ID is not 0, the dentry is added to the circular
+ * linked list for that hard link group.
*
- * If the hard link group ID is 0, this is a no-op and the dentry is not
- * inserted.
+ * If the hard link group ID is 0, this indicates a dentry that's in a hard link
+ * group by itself (has a link count of 1). We can't insert it into the hash
+ * table itself because we don't know what hard link group IDs are available to
+ * give it (this could be kept track of but would be more difficult). Instead
+ * we keep a linked list of the single dentries, and assign them hard link group
+ * IDs later.
*/
-int link_group_table_insert(struct dentry *dentry, struct link_group_table *table)
+int link_group_table_insert(struct dentry *dentry, void *__table)
{
+ struct link_group_table *table = __table;
size_t pos;
struct link_group *group;
- if (dentry->hard_link == 0)
- return 0;
+ if (dentry->link_group_id == 0) {
+ /* Single group--- Add to the list of extra groups (we can't put
+ * it in the table itself because all the singles have a link
+ * group ID of 0) */
+ group = MALLOC(sizeof(struct link_group));
+ if (!group)
+ return WIMLIB_ERR_NOMEM;
+ group->link_group_id = 0;
+ group->next = table->extra_groups;
+ table->extra_groups = group;
+ INIT_LIST_HEAD(&dentry->link_group_list);
+ group->dentry_list = &dentry->link_group_list;
+ } else {
+ /* Hard link group that may contain multiple dentries (the code
+ * will work even if the group actually contains only 1 dentry
+ * though) */
- /* Try adding to existing hard link group */
- pos = dentry->hard_link % table->capacity;
- group = table->array[pos];
- while (group) {
- if (group->link_group_id == dentry->hard_link) {
- list_add(&dentry->link_group_list, &group->dentry_list);
- return 0;
+ /* Try adding to existing hard link group */
+ pos = dentry->link_group_id % table->capacity;
+ group = table->array[pos];
+ while (group) {
+ if (group->link_group_id == dentry->link_group_id) {
+ list_add(&dentry->link_group_list,
+ group->dentry_list);
+ return 0;
+ }
+ group = group->next;
}
- group = group->next;
- }
- /* Add new hard link group to the table */
+ /* Add new hard link group to the table */
- group = MALLOC(sizeof(struct link_group));
- if (!group)
- return WIMLIB_ERR_NOMEM;
- group->link_group_id = dentry->hard_link;
- group->next = table->array[pos];
- INIT_LIST_HEAD(&group->dentry_list);
- list_add(&dentry->link_group_list, &group->dentry_list);
- table->array[pos] = group;
+ group = MALLOC(sizeof(struct link_group));
+ if (!group)
+ return WIMLIB_ERR_NOMEM;
+ group->link_group_id = dentry->link_group_id;
+ group->next = table->array[pos];
+ INIT_LIST_HEAD(&dentry->link_group_list);
+ group->dentry_list = &dentry->link_group_list;
+ table->array[pos] = group;
- /* XXX Make the table grow when too many entries have been inserted. */
- table->num_entries++;
+ /* XXX Make the table grow when too many entries have been
+ * inserted. */
+ table->num_entries++;
+ }
return 0;
}
+static void free_link_group_list(struct link_group *group)
+{
+ struct link_group *next_group;
+ while (group) {
+ next_group = group->next;
+ FREE(group);
+ group = next_group;
+ }
+}
+
/* Frees a link group table. */
void free_link_group_table(struct link_group_table *table)
{
- if (!table)
- return;
- if (table->array) {
- for (u64 i = 0; i < table->capacity; i++) {
- struct link_group *group = table->array[i];
- struct link_group *next;
- while (group) {
- next = group->next;
- FREE(group);
- group = next;
- }
- }
- FREE(table->array);
+ if (table) {
+ if (table->array)
+ for (size_t i = 0; i < table->capacity; i++)
+ free_link_group_list(table->array[i]);
+ free_link_group_list(table->extra_groups);
+ FREE(table);
+ }
+}
+
+static u64
+assign_link_group_ids_to_list(struct link_group *group, u64 id,
+ struct link_group **extra_groups)
+{
+ struct dentry *dentry;
+ struct list_head *cur_head;
+ struct link_group *prev_group = NULL;
+ struct link_group *cur_group = group;
+ while (cur_group) {
+ cur_head = cur_group->dentry_list;
+ do {
+ dentry = container_of(cur_head,
+ struct dentry,
+ link_group_list);
+ dentry->link_group_id = id;
+ cur_head = cur_head->next;
+ } while (cur_head != cur_group->dentry_list);
+ cur_group->link_group_id = id;
+ id++;
+ prev_group = cur_group;
+ cur_group = cur_group->next;
+ }
+ if (group && extra_groups) {
+ prev_group->next = *extra_groups;
+ *extra_groups = group;
+ }
+ return id;
+}
+
+/* Insert the link groups in the `extra_groups' list into the hash table */
+static void insert_extra_groups(struct link_group_table *table)
+{
+ struct link_group *group, *next_group;
+ size_t pos;
+
+ group = table->extra_groups;
+ while (group) {
+ next_group = group->next;
+ pos = group->link_group_id % table->capacity;
+ group->next = table->array[pos];
+ table->array[pos] = group;
+ group = next_group;
}
- FREE(table);
+ table->extra_groups = NULL;
}
/* Assign the link group IDs to dentries in a link group table, and return the
* next available link group ID. */
-u64 assign_link_groups(struct link_group_table *table)
+u64 assign_link_group_ids(struct link_group_table *table)
{
- struct link_group *remaining_groups = NULL;
+ DEBUG("Assigning link groups");
+ struct link_group *extra_groups = table->extra_groups;
+
+ /* Assign consecutive link group IDs to each link group in the hash
+ * table */
u64 id = 1;
- for (u64 i = 0; i < table->capacity; i++) {
- struct link_group *group = table->array[i];
- struct link_group *next_group;
- struct dentry *dentry;
- while (group) {
- next_group = group->next;
- if (list_is_singular(&group->dentry_list)) {
- /* Hard link group of size 1. Change the hard
- * link ID to 0 and discard the link_group */
- dentry = container_of(group->dentry_list.next,
- struct dentry,
- link_group_list);
- dentry->hard_link = 0;
- FREE(group);
+ for (size_t i = 0; i < table->capacity; i++) {
+ id = assign_link_group_ids_to_list(table->array[i], id,
+ &table->extra_groups);
+ table->array[i] = NULL;
+ }
+
+ /* Assign link group IDs to the "extra" link groups and insert them into
+ * the hash table */
+ id = assign_link_group_ids_to_list(extra_groups, id, NULL);
+ insert_extra_groups(table);
+ return id;
+}
+
+
+
+static void inconsistent_link_group(const struct dentry *first_dentry)
+{
+ const struct dentry *dentry = first_dentry;
+
+ ERROR("An inconsistent hard link group that we cannot correct has been "
+ "detected");
+ ERROR("The dentries are located at the following paths:");
+ do {
+ ERROR("`%s'", dentry->full_path_utf8);
+ } while ((dentry = container_of(dentry->link_group_list.next,
+ const struct dentry,
+ link_group_list)) != first_dentry);
+}
+
+static bool ref_dentries_consistent(const struct dentry * restrict ref_dentry_1,
+ const struct dentry * restrict ref_dentry_2)
+{
+ wimlib_assert(ref_dentry_1 != ref_dentry_2);
+
+ if (ref_dentry_1->num_ads != ref_dentry_2->num_ads)
+ return false;
+ if (ref_dentry_1->security_id != ref_dentry_2->security_id
+ || ref_dentry_1->attributes != ref_dentry_2->attributes)
+ return false;
+ for (unsigned i = 0; i <= ref_dentry_1->num_ads; i++) {
+ const u8 *ref_1_hash, *ref_2_hash;
+ ref_1_hash = dentry_stream_hash(ref_dentry_1, i);
+ ref_2_hash = dentry_stream_hash(ref_dentry_2, i);
+ if (!hashes_equal(ref_1_hash, ref_2_hash))
+ return false;
+ if (i && !ads_entries_have_same_name(&ref_dentry_1->ads_entries[i - 1],
+ &ref_dentry_2->ads_entries[i - 1]))
+ return false;
+
+ }
+ return true;
+}
+
+static bool dentries_consistent(const struct dentry * restrict ref_dentry,
+ const struct dentry * restrict dentry)
+{
+ wimlib_assert(ref_dentry != dentry);
+
+ if (ref_dentry->num_ads != dentry->num_ads && dentry->num_ads != 0)
+ return false;
+ if (ref_dentry->security_id != dentry->security_id
+ || ref_dentry->attributes != dentry->attributes)
+ return false;
+ for (unsigned i = 0; i <= min(ref_dentry->num_ads, dentry->num_ads); i++) {
+ const u8 *ref_hash, *hash;
+ ref_hash = dentry_stream_hash(ref_dentry, i);
+ hash = dentry_stream_hash(dentry, i);
+ if (!hashes_equal(ref_hash, hash) && !is_zero_hash(hash))
+ return false;
+ if (i && !ads_entries_have_same_name(&ref_dentry->ads_entries[i - 1],
+ &dentry->ads_entries[i - 1]))
+ return false;
+ }
+ return true;
+}
+
+#ifdef ENABLE_DEBUG
+static void
+print_dentry_list(const struct dentry *first_dentry)
+{
+ const struct dentry *dentry = first_dentry;
+ do {
+ printf("`%s'\n", dentry->full_path_utf8);
+ } while ((dentry = container_of(dentry->link_group_list.next,
+ struct dentry,
+ link_group_list)) != first_dentry);
+}
+#endif
+
+/* Fix up a "true" link group and check for inconsistencies */
+static int
+fix_true_link_group(struct dentry *first_dentry)
+{
+ struct dentry *dentry;
+ struct dentry *ref_dentry = NULL;
+ u64 last_ctime = 0;
+ u64 last_mtime = 0;
+ u64 last_atime = 0;
+ bool found_short_name = false;
+
+ dentry = first_dentry;
+ do {
+ if (!ref_dentry || ref_dentry->num_ads == 0)
+ ref_dentry = dentry;
+ if (dentry->short_name_len) {
+ if (found_short_name) {
+ ERROR("Multiple short names in hard link "
+ "group!");
+ inconsistent_link_group(first_dentry);
+ return WIMLIB_ERR_INVALID_DENTRY;
} else {
- /* Hard link group of size > 1. Assign the
- * dentries in the group the next available hard
- * link IDs and queue the group to be
- * re-inserted into the table. */
- list_for_each_entry(dentry, &group->dentry_list,
- link_group_list)
- dentry->hard_link = id;
- group->next = remaining_groups;
- remaining_groups = group;
- id++;
+ found_short_name = true;
+ }
+ }
+ if (dentry->creation_time > last_ctime)
+ last_ctime = dentry->creation_time;
+ if (dentry->last_write_time > last_mtime)
+ last_mtime = dentry->last_write_time;
+ if (dentry->last_access_time > last_atime)
+ last_atime = dentry->last_access_time;
+ } while ((dentry = container_of(dentry->link_group_list.next,
+ struct dentry,
+ link_group_list)) != first_dentry);
+
+
+ ref_dentry->ads_entries_status = ADS_ENTRIES_OWNER;
+ dentry = first_dentry;
+ do {
+ if (dentry != ref_dentry) {
+ if (!dentries_consistent(ref_dentry, dentry)) {
+ inconsistent_link_group(first_dentry);
+ return WIMLIB_ERR_INVALID_DENTRY;
+ }
+ copy_hash(dentry->hash, ref_dentry->hash);
+ dentry_free_ads_entries(dentry);
+ dentry->num_ads = ref_dentry->num_ads;
+ dentry->ads_entries = ref_dentry->ads_entries;
+ dentry->ads_entries_status = ADS_ENTRIES_USER;
+ }
+ dentry->creation_time = last_ctime;
+ dentry->last_write_time = last_mtime;
+ dentry->last_access_time = last_atime;
+ } while ((dentry = container_of(dentry->link_group_list.next,
+ struct dentry,
+ link_group_list)) != first_dentry);
+ return 0;
+}
+
+/*
+ * Fixes up a nominal link group.
+ *
+ * By a nominal link group we mean a group of two or more dentries that share
+ * the same hard link group ID.
+ *
+ * If dentries in the group are found to be inconsistent, we may split the group
+ * into several "true" hard link groups. @new_groups points to a linked list of
+ * these split groups, and if we create any, they will be added to this list.
+ *
+ * After splitting up each nominal link group into the "true" link groups we
+ * will canonicalize the link groups. To do this, we:
+ *
+ * - Assign all the dentries in the link group the most recent timestamp
+ * among all the corresponding timestamps in the link group, for each of
+ * the three categories of time stamps.
+ *
+ * - Make sure the dentry->hash field is valid in all the dentries, if
+ * possible (this field may be all zeroes, and in the context of a hard
+ * link group this must be interpreted as implicitly refering to the same
+ * stream as another dentry in the hard link group that does NOT have all
+ * zeroes for this field).
+ *
+ * - Make sure dentry->num_ads is the same in all the dentries in the link
+ * group. In some cases, it's possible for it to be set to 0 when it
+ * actually must be interpreted as being the same as the number of
+ * alternate data streams in another dentry in the hard link group that has
+ * a nonzero number of alternate data streams.
+ *
+ * - Make sure only the dentry->ads_entries array is only allocated for one
+ * dentry in the hard link group. This dentry will have
+ * dentry->ads_entries_status set to ADS_ENTRIES_OWNER, while the others
+ * will have dentry->ads_entries_status set to ADS_ENTRIES_USER.
+ */
+static int
+fix_nominal_link_group(struct link_group *group,
+ struct link_group **new_groups)
+{
+ struct dentry *tmp, *dentry, *ref_dentry;
+ int ret;
+ size_t num_true_link_groups;
+ struct list_head *head;
+
+ LIST_HEAD(dentries_with_data_streams);
+ LIST_HEAD(dentries_with_no_data_streams);
+ LIST_HEAD(true_link_groups);
+
+ /* Create a list of dentries in the nominal hard link group that have at
+ * least one data stream with a non-zero hash, and another list that
+ * contains the dentries that have a zero hash for all data streams. */
+ dentry = container_of(group->dentry_list, struct dentry,
+ link_group_list);
+ do {
+ for (unsigned i = 0; i <= dentry->num_ads; i++) {
+ const u8 *hash;
+ hash = dentry_stream_hash(dentry, i);
+ if (!is_zero_hash(hash)) {
+ list_add(&dentry->tmp_list,
+ &dentries_with_data_streams);
+ goto next_dentry;
}
- group = next_group;
}
+ list_add(&dentry->tmp_list,
+ &dentries_with_no_data_streams);
+ next_dentry:
+ dentry = container_of(dentry->link_group_list.next,
+ struct dentry,
+ link_group_list);
+ } while (&dentry->link_group_list != group->dentry_list);
+
+ /* If there are no dentries with data streams, we require the nominal
+ * link group to be a true link group */
+ if (list_empty(&dentries_with_data_streams)) {
+ #ifdef ENABLE_DEBUG
+ {
+ size_t size = dentry_link_group_size(dentry);
+ if (size > 1) {
+ DEBUG("Found link group of size %zu without "
+ "any data streams:", size);
+ print_dentry_list(dentry);
+ DEBUG("We are going to interpret it as true "
+ "link group, provided that the dentries "
+ "are consistent.");
+ }
+ }
+ #endif
+ return fix_true_link_group(container_of(group->dentry_list,
+ struct dentry,
+ link_group_list));
}
- memset(table->array, 0, table->capacity * sizeof(table->array[0]));
- table->num_entries = 0;
- while (remaining_groups) {
- struct link_group *group = remaining_groups;
- size_t pos = group->link_group_id % table->capacity;
- table->num_entries++;
- group->next = table->array[pos];
- table->array[pos] = group;
- remaining_groups = remaining_groups->next;
+ /* One or more dentries had data streams specified. We check each of
+ * these dentries for consistency with the others to form a set of true
+ * link groups. */
+ num_true_link_groups = 0;
+ list_for_each_entry_safe(dentry, tmp, &dentries_with_data_streams,
+ tmp_list)
+ {
+ list_del(&dentry->tmp_list);
+
+ /* Look for a true link group that is consistent with
+ * this dentry and add this dentry to it. Or, if none
+ * of the true link groups are consistent with this
+ * dentry, make a new one. */
+ list_for_each_entry(ref_dentry, &true_link_groups, tmp_list) {
+ if (ref_dentries_consistent(ref_dentry, dentry)) {
+ list_add(&dentry->link_group_list,
+ &ref_dentry->link_group_list);
+ goto next_dentry_2;
+ }
+ }
+ num_true_link_groups++;
+ list_add(&dentry->tmp_list, &true_link_groups);
+ INIT_LIST_HEAD(&dentry->link_group_list);
+next_dentry_2:
+ ;
}
- return id;
+
+ wimlib_assert(num_true_link_groups != 0);
+
+ /* If there were dentries with no data streams, we require there to only
+ * be one true link group so that we know which link group to assign the
+ * streamless dentries to. */
+ if (!list_empty(&dentries_with_no_data_streams)) {
+ if (num_true_link_groups != 1) {
+ ERROR("Hard link group ambiguity detected!");
+ ERROR("We split up hard link group 0x%"PRIx64" due to "
+ "inconsistencies,", group->link_group_id);
+ ERROR("but dentries with no stream information remained. "
+ "We don't know which true hard link");
+ ERROR("group to assign them to.");
+ return WIMLIB_ERR_INVALID_DENTRY;
+ }
+ /* Assign the streamless dentries to the one and only true link
+ * group. */
+ ref_dentry = container_of(true_link_groups.next,
+ struct dentry,
+ tmp_list);
+ list_for_each_entry(dentry, &dentries_with_no_data_streams, tmp_list)
+ list_add(&dentry->link_group_list, &ref_dentry->link_group_list);
+ }
+ if (num_true_link_groups != 1) {
+ #ifdef ENABLE_DEBUG
+ {
+ printf("Split nominal link group 0x%"PRIx64" into %zu "
+ "link groups:\n",
+ group->link_group_id, num_true_link_groups);
+ puts("------------------------------------------------------------------------------");
+ size_t i = 1;
+ list_for_each_entry(dentry, &true_link_groups, tmp_list) {
+ printf("[Split link group %zu]\n", i++);
+ print_dentry_list(dentry);
+ putchar('\n');
+ }
+ puts("------------------------------------------------------------------------------");
+ }
+ #endif
+ }
+
+ list_for_each_entry(dentry, &true_link_groups, tmp_list) {
+ ret = fix_true_link_group(dentry);
+ if (ret != 0)
+ return ret;
+ }
+
+ /* Make new `struct link_group's for the new link groups */
+ for (head = true_link_groups.next->next;
+ head != &true_link_groups;
+ head = head->next)
+ {
+ dentry = container_of(head, struct dentry, tmp_list);
+ group = MALLOC(sizeof(*group));
+ if (!group) {
+ ERROR("Out of memory");
+ return WIMLIB_ERR_NOMEM;
+ }
+ group->link_group_id = dentry->link_group_id;
+ group->dentry_list = &dentry->link_group_list;
+ group->next = *new_groups;
+ *new_groups = group;
+ }
+ return 0;
}
-#if 0
-/* Load a dentry tree into the link group table */
-int load_link_groups(struct link_group_table *table, struct dentry *root)
+/*
+ * Goes through each link group and shares the ads_entries (Alternate Data
+ * Stream entries) field of each dentry among members of a hard link group.
+ *
+ * In the process, the dentries in each link group are checked for consistency.
+ * If they contain data features that indicate they cannot really be in the same
+ * hard link group, this should be an error, but in reality this case needs to
+ * be handled, so we split the dentries into different hard link groups.
+ *
+ * One of the dentries in each hard link group group is arbitrarily assigned the
+ * role of "owner" of the memory pointed to by the @ads_entries field,
+ * (ADS_ENTRIES_OWNER), while the others are "users" (ADS_ENTRIES_USER) who are
+ * not allowed to free the memory.
+ */
+int fix_link_groups(struct link_group_table *table)
{
- int ret = for_dentry_in_tree(dentry, link_group_table_insert, table);
- if (ret == 0)
- assign_link_groups(table);
- return ret;
+ for (u64 i = 0; i < table->capacity; i++) {
+ struct link_group *group = table->array[i];
+ while (group) {
+ int ret;
+ ret = fix_nominal_link_group(group, &table->extra_groups);
+ if (ret != 0)
+ return ret;
+ group = group->next;
+ }
+ }
+ return 0;
}
-#endif
git://wimlib.net / wimlib / blobdiff