/* * hardlink.c * * Code to deal with hard links in WIMs. */ /* * 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 * \ / | wim_inode| | wim_inode| * dentry ------------ ------------ * ^ ^ * | | * | | dentry * ----------- ----------- / \ * dentry<---| struct | | struct |---> dentry dentry * / | wim_inode| | wim_inode| \ / * dentry ------------ ------------ dentry * ^ ^ * | | * ----------------- * wim_inode_table->array | idx 0 | idx 1 | * ----------------- */ /* Hash table to find inodes, identified by their inode ID. * */ struct wim_inode_table { /* Fields for the hash table */ struct hlist_head *array; u64 num_entries; u64 capacity; /* * Linked list of "extra" inodes. These may be: * * - inodes with link count 1, which are all allowed to have 0 for their * inode number, meaning we cannot insert them into the hash table * before calling assign_inode_numbers(). * * - Groups we create ourselves by splitting a nominal inode due to * inconsistencies in the dentries. These inodes will share a inode * number with some other inode until assign_inode_numbers() is * called. */ struct hlist_head extra_inodes; }; static inline void destroy_inode_table(struct wim_inode_table *table) { FREE(table->array); } static int init_inode_table(struct wim_inode_table *table, size_t capacity) { table->array = CALLOC(capacity, sizeof(table->array[0])); if (!table->array) { ERROR("Cannot initalize inode table: out of memory"); return WIMLIB_ERR_NOMEM; } table->num_entries = 0; table->capacity = capacity; INIT_HLIST_HEAD(&table->extra_inodes); return 0; } static inline size_t inode_link_count(const struct wim_inode *inode) { const struct list_head *cur; size_t size = 0; list_for_each(cur, &inode->i_dentry) size++; return size; } /* Insert a dentry into the inode table based on the inode number of the * attached inode (which came from the hard link group ID field of the on-disk * WIM dentry) */ static int inode_table_insert(struct wim_dentry *dentry, void *__table) { struct wim_inode_table *table = __table; struct wim_inode *d_inode = dentry->d_inode; if (d_inode->i_ino == 0) { /* A dentry with a hard link group ID of 0 indicates that it's * in a hard link group by itself. Add it to the list of extra * inodes rather than inserting it into the hash lists. */ hlist_add_head(&d_inode->i_hlist, &table->extra_inodes); wimlib_assert(d_inode->i_dentry.next == &dentry->d_alias); wimlib_assert(d_inode->i_dentry.prev == &dentry->d_alias); wimlib_assert(d_inode->i_nlink == 1); } else { size_t pos; struct wim_inode *inode; struct hlist_node *cur; /* Try adding this dentry to an existing inode */ pos = d_inode->i_ino % table->capacity; hlist_for_each_entry(inode, cur, &table->array[pos], i_hlist) { if (inode->i_ino == d_inode->i_ino) { inode_add_dentry(dentry, inode); inode->i_nlink++; return 0; } } /* No inode in the table has the same number as this one, so add * it to the table. */ hlist_add_head(&d_inode->i_hlist, &table->array[pos]); wimlib_assert(d_inode->i_dentry.next == &dentry->d_alias); wimlib_assert(d_inode->i_dentry.prev == &dentry->d_alias); wimlib_assert(d_inode->i_nlink == 1); /* XXX Make the table grow when too many entries have been * inserted. */ table->num_entries++; } return 0; } static void print_inode_dentries(const struct wim_inode *inode) { struct wim_dentry *dentry; inode_for_each_dentry(dentry, inode) printf("`%s'\n", dentry->full_path_utf8); } static void inconsistent_inode(const struct wim_inode *inode) { ERROR("An inconsistent hard link group that cannot be corrected has " "been detected"); ERROR("The dentries are located at the following paths:"); #ifdef ENABLE_ERROR_MESSAGES print_inode_dentries(inode); #endif } static bool ref_inodes_consistent(const struct wim_inode * restrict ref_inode_1, const struct wim_inode * restrict ref_inode_2) { wimlib_assert(ref_inode_1 != ref_inode_2); if (ref_inode_1->i_num_ads != ref_inode_2->i_num_ads) return false; if (ref_inode_1->i_security_id != ref_inode_2->i_security_id || ref_inode_1->i_attributes != ref_inode_2->i_attributes) return false; for (unsigned i = 0; i <= ref_inode_1->i_num_ads; i++) { const u8 *ref_1_hash, *ref_2_hash; ref_1_hash = inode_stream_hash(ref_inode_1, i); ref_2_hash = inode_stream_hash(ref_inode_2, i); if (!hashes_equal(ref_1_hash, ref_2_hash)) return false; if (i && !ads_entries_have_same_name(&ref_inode_1->i_ads_entries[i - 1], &ref_inode_2->i_ads_entries[i - 1])) return false; } return true; } static bool inodes_consistent(const struct wim_inode * restrict ref_inode, const struct wim_inode * restrict inode) { wimlib_assert(ref_inode != inode); if (ref_inode->i_num_ads != inode->i_num_ads && inode->i_num_ads != 0) return false; if (ref_inode->i_security_id != inode->i_security_id || ref_inode->i_attributes != inode->i_attributes) return false; for (unsigned i = 0; i <= min(ref_inode->i_num_ads, inode->i_num_ads); i++) { const u8 *ref_hash, *hash; ref_hash = inode_stream_hash(ref_inode, i); hash = inode_stream_hash(inode, i); if (!hashes_equal(ref_hash, hash) && !is_zero_hash(hash)) return false; if (i && !ads_entries_have_same_name(&ref_inode->i_ads_entries[i - 1], &inode->i_ads_entries[i - 1])) return false; } return true; } /* Fix up a "true" inode and check for inconsistencies */ static int fix_true_inode(struct wim_inode *inode, struct hlist_head *inode_list) { struct wim_dentry *dentry; struct wim_dentry *ref_dentry = NULL; struct wim_inode *ref_inode; u64 last_ctime = 0; u64 last_mtime = 0; u64 last_atime = 0; inode_for_each_dentry(dentry, inode) { if (!ref_dentry || dentry->d_inode->i_num_ads > ref_dentry->d_inode->i_num_ads) ref_dentry = dentry; if (dentry->d_inode->i_creation_time > last_ctime) last_ctime = dentry->d_inode->i_creation_time; if (dentry->d_inode->i_last_write_time > last_mtime) last_mtime = dentry->d_inode->i_last_write_time; if (dentry->d_inode->i_last_access_time > last_atime) last_atime = dentry->d_inode->i_last_access_time; } ref_inode = ref_dentry->d_inode; ref_inode->i_nlink = 1; hlist_add_head(&ref_inode->i_hlist, inode_list); list_del(&inode->i_dentry); list_add(&ref_inode->i_dentry, &ref_dentry->d_alias); inode_for_each_dentry(dentry, ref_inode) { if (dentry != ref_dentry) { if (!inodes_consistent(ref_inode, dentry->d_inode)) { inconsistent_inode(ref_inode); return WIMLIB_ERR_INVALID_DENTRY; } /* Free the unneeded `struct wim_inode'. */ dentry->d_inode->i_hlist.next = NULL; dentry->d_inode->i_hlist.pprev = NULL; free_inode(dentry->d_inode); dentry->d_inode = ref_inode; ref_inode->i_nlink++; } } ref_inode->i_creation_time = last_ctime; ref_inode->i_last_write_time = last_mtime; ref_inode->i_last_access_time = last_atime; wimlib_assert(inode_link_count(ref_inode) == ref_inode->i_nlink); return 0; } /* * Fixes up a nominal inode. * * By a nominal inode we mean a group of two or more dentries that share the * same hard link group ID. * * If dentries in the inode are found to be inconsistent, we may split the inode * into several "true" inodes. * * After splitting up each nominal inode into the "true" inodes we will * canonicalize the link group by getting rid of all the unnecessary `struct * wim_inode's. There will be just one `struct wim_inode' for each hard link * group remaining. */ static int fix_nominal_inode(struct wim_inode *inode, struct hlist_head *inode_list) { struct wim_dentry *dentry; struct hlist_node *cur, *tmp; int ret; size_t num_true_inodes; wimlib_assert(inode->i_nlink == inode_link_count(inode)); LIST_HEAD(dentries_with_data_streams); LIST_HEAD(dentries_with_no_data_streams); HLIST_HEAD(true_inodes); /* Create a list of dentries in the nominal inode 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. */ inode_for_each_dentry(dentry, inode) { for (unsigned i = 0; i <= dentry->d_inode->i_num_ads; i++) { const u8 *hash; hash = inode_stream_hash(dentry->d_inode, i); if (!is_zero_hash(hash)) { list_add(&dentry->tmp_list, &dentries_with_data_streams); goto next_dentry; } } list_add(&dentry->tmp_list, &dentries_with_no_data_streams); next_dentry: ; } /* If there are no dentries with data streams, we require the nominal * inode to be a true inode */ if (list_empty(&dentries_with_data_streams)) { #ifdef ENABLE_DEBUG if (inode->i_nlink > 1) { DEBUG("Found link group of size %u without " "any data streams:", inode->i_nlink); print_inode_dentries(inode); DEBUG("We are going to interpret it as true " "link group, provided that the dentries " "are consistent."); } #endif return fix_true_inode(inode, inode_list); } /* 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 * inodes. */ num_true_inodes = 0; list_for_each_entry(dentry, &dentries_with_data_streams, tmp_list) { /* Look for a true inode that is consistent with this dentry and * add this dentry to it. Or, if none of the true inodes are * consistent with this dentry, add a new one (if that happens, * we have split the hard link group). */ hlist_for_each_entry(inode, cur, &true_inodes, i_hlist) { if (ref_inodes_consistent(inode, dentry->d_inode)) { inode_add_dentry(dentry, inode); goto next_dentry_2; } } num_true_inodes++; INIT_LIST_HEAD(&dentry->d_inode->i_dentry); inode_add_dentry(dentry, dentry->d_inode); hlist_add_head(&dentry->d_inode->i_hlist, &true_inodes); next_dentry_2: ; } wimlib_assert(num_true_inodes != 0); /* If there were dentries with no data streams, we require there to only * be one true inode so that we know which inode to assign the * streamless dentries to. */ if (!list_empty(&dentries_with_no_data_streams)) { if (num_true_inodes != 1) { ERROR("Hard inode ambiguity detected!"); ERROR("We split up inode 0x%"PRIx64" due to " "inconsistencies,", inode->i_ino); ERROR("but dentries with no stream information remained. " "We don't know which inode"); ERROR("to assign them to."); return WIMLIB_ERR_INVALID_DENTRY; } inode = container_of(true_inodes.first, struct wim_inode, i_hlist); /* Assign the streamless dentries to the one and only true * inode. */ list_for_each_entry(dentry, &dentries_with_no_data_streams, tmp_list) inode_add_dentry(dentry, inode); } #ifdef ENABLE_DEBUG if (num_true_inodes != 1) { inode = container_of(true_inodes.first, struct wim_inode, i_hlist); printf("Split nominal inode 0x%"PRIx64" into %zu " "inodes:\n", inode->i_ino, num_true_inodes); puts("------------------------------------------------------------------------------"); size_t i = 1; hlist_for_each_entry(inode, cur, &true_inodes, i_hlist) { printf("[Split inode %zu]\n", i++); print_inode_dentries(inode); putchar('\n'); } puts("------------------------------------------------------------------------------"); } #endif hlist_for_each_entry_safe(inode, cur, tmp, &true_inodes, i_hlist) { ret = fix_true_inode(inode, inode_list); if (ret != 0) return ret; } return 0; } static int fix_inodes(struct wim_inode_table *table, struct hlist_head *inode_list) { struct wim_inode *inode; struct hlist_node *cur, *tmp; int ret; INIT_HLIST_HEAD(inode_list); for (u64 i = 0; i < table->capacity; i++) { hlist_for_each_entry_safe(inode, cur, tmp, &table->array[i], i_hlist) { ret = fix_nominal_inode(inode, inode_list); if (ret != 0) return ret; } } hlist_for_each_safe(cur, tmp, &table->extra_inodes) hlist_add_head(cur, inode_list); return 0; } /* * dentry_tree_fix_inodes(): * * This function takes as input a tree of WIM dentries that initially has a * different inode associated with each dentry. Sets of dentries that should * share the same inode (a.k.a. hard link groups) are built using the i_ino * field of each inode, then the link count and alias list for one inode in each * set is set correctly and the unnecessary struct wim_inode's freed. The * effect is to correctly associate exactly one struct wim_inode with each * original inode, regardless of how many dentries are aliases for that inode. * * The special inode number of 0 indicates that the dentry is in a hard link * group by itself, and therefore has a 'struct wim_inode' with i_nlink=1 to * itself. * * This function also checks the dentries in each hard link group for * consistency. In some WIMs, such as install.wim for some versions of Windows * 7, dentries can share the same hard link group ID but not actually be hard * linked to each other (based on conflicting information, such as file * contents). This should be an error, but this case needs be handled. So, * each "nominal" inode (the inode based on the inode numbers provided in the * WIM) is examined for consistency and may be split into multiple "true" inodes * that are maximally sized consistent sets of dentries. * * Return 0 on success; WIMLIB_ERR_NOMEM or WIMLIB_ERR_INVALID_DENTRY on * failure. On success, the list of "true" inodes, linked by the i_hlist field, * is returned in the hlist @inode_list. */ int dentry_tree_fix_inodes(struct wim_dentry *root, struct hlist_head *inode_list) { struct wim_inode_table inode_tab; int ret; DEBUG("Inserting dentries into inode table"); ret = init_inode_table(&inode_tab, 9001); if (ret != 0) return ret; for_dentry_in_tree(root, inode_table_insert, &inode_tab); DEBUG("Cleaning up the hard link groups"); ret = fix_inodes(&inode_tab, inode_list); destroy_inode_table(&inode_tab); return ret; } /* Assign inode numbers to a list of inodes and return the next available * number. */ u64 assign_inode_numbers(struct hlist_head *inode_list) { DEBUG("Assigning inode numbers"); struct wim_inode *inode; struct hlist_node *cur; u64 cur_ino = 1; hlist_for_each_entry(inode, cur, inode_list, i_hlist) { inode->i_ino = cur_ino; cur_ino++; } return cur_ino; }