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   1 /*
   2  * lookup_table.c
   3  *
   4  * Lookup table, implemented as a hash table, that maps dentries to file
   5  * resources.
   6  */
   7
   8 /*
   9  * Copyright (C) 2012 Eric Biggers
  10  *
  11  * This file is part of wimlib, a library for working with WIM files.
  12  *
  13  * wimlib is free software; you can redistribute it and/or modify it under the
  14  * terms of the GNU Lesser General Public License as published by the Free
  15  * Software Foundation; either version 2.1 of the License, or (at your option)
  16  * any later version.
  17  *
  18  * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
  19  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  20  * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  21  * details.
  22  *
  23  * You should have received a copy of the GNU Lesser General Public License
  24  * along with wimlib; if not, see http://www.gnu.org/licenses/.
  25  */
  26
  27 #include "wimlib_internal.h"
  28 #include "lookup_table.h"
  29 #include "io.h"
  30 #include <errno.h>
  31
  32 struct lookup_table *new_lookup_table(size_t capacity)
  33 {
  34         struct lookup_table *table;
  35         struct hlist_head *array;
  36
  37         table = MALLOC(sizeof(struct lookup_table));
  38         if (!table)
  39                 goto err;
  40         array = CALLOC(capacity, sizeof(array[0]));
  41         if (!array) {
  42                 FREE(table);
  43                 goto err;
  44         }
  45         table->num_entries = 0;
  46         table->capacity = capacity;
  47         table->array = array;
  48         return table;
  49 err:
  50         ERROR("Failed to allocate memory for lookup table with capacity %zu",
  51               capacity);
  52         return NULL;
  53 }
  54
  55 struct lookup_table_entry *new_lookup_table_entry()
  56 {
  57         struct lookup_table_entry *lte;
  58
  59         lte = CALLOC(1, sizeof(struct lookup_table_entry));
  60         if (!lte) {
  61                 ERROR("Out of memory (tried to allocate %zu bytes for "
  62                       "lookup table entry)",
  63                       sizeof(struct lookup_table_entry));
  64                 return NULL;
  65         }
  66
  67         lte->part_number  = 1;
  68         lte->refcnt       = 1;
  69         INIT_LIST_HEAD(&lte->lte_group_list);
  70         return lte;
  71 }
  72
  73 void free_lookup_table_entry(struct lookup_table_entry *lte)
  74 {
  75         if (lte) {
  76                 if (lte->staging_list.next)
  77                         list_del(&lte->staging_list);
  78                 FREE(lte->file_on_disk);
  79                 FREE(lte);
  80         }
  81 }
  82
  83 static int do_free_lookup_table_entry(struct lookup_table_entry *entry,
  84                                       void *ignore)
  85 {
  86         free_lookup_table_entry(entry);
  87         return 0;
  88 }
  89
  90
  91 void free_lookup_table(struct lookup_table *table)
  92 {
  93         DEBUG("Freeing lookup table");
  94         if (table) {
  95                 if (table->array) {
  96                         for_lookup_table_entry(table,
  97                                                do_free_lookup_table_entry,
  98                                                NULL);
  99                         FREE(table->array);
 100                 }
 101                 FREE(table);
 102         }
 103 }
 104
 105 /*
 106  * Inserts an entry into the lookup table.
 107  *
 108  * @table:      A pointer to the lookup table.
 109  * @entry:      A pointer to the entry to insert.
 110  */
 111 void lookup_table_insert(struct lookup_table *table,
 112                          struct lookup_table_entry *lte)
 113 {
 114         size_t i = lte->hash_short % table->capacity;
 115         hlist_add_head(&lte->hash_list, &table->array[i]);
 116
 117         /* XXX Make the table grow when too many entries have been inserted. */
 118         table->num_entries++;
 119 }
 120
 121
 122
 123 /* Decrements the reference count for the lookup table entry @lte.  If its
 124  * reference count reaches 0, it is unlinked from the lookup table.  If,
 125  * furthermore, the entry has no opened file descriptors associated with it, the
 126  * entry is freed.  */
 127 struct lookup_table_entry *
 128 lte_decrement_refcnt(struct lookup_table_entry *lte, struct lookup_table *table)
 129 {
 130         if (lte) {
 131                 wimlib_assert(lte->refcnt);
 132                 if (--lte->refcnt == 0) {
 133                         lookup_table_unlink(table, lte);
 134                         if (lte->num_opened_fds == 0) {
 135                                 free_lookup_table_entry(lte);
 136                                 lte = NULL;
 137                         }
 138                 }
 139         }
 140         return lte;
 141 }
 142
 143 /*
 144  * Calls a function on all the entries in the lookup table.  Stop early and
 145  * return nonzero if any call to the function returns nonzero.
 146  */
 147 int for_lookup_table_entry(struct lookup_table *table,
 148                            int (*visitor)(struct lookup_table_entry *, void *),
 149                            void *arg)
 150 {
 151         struct lookup_table_entry *lte;
 152         struct hlist_node *pos, *tmp;
 153         int ret;
 154
 155         for (size_t i = 0; i < table->capacity; i++) {
 156                 hlist_for_each_entry_safe(lte, pos, tmp, &table->array[i],
 157                                           hash_list)
 158                 {
 159                         ret = visitor(lte, arg);
 160                         if (ret != 0)
 161                                 return ret;
 162                 }
 163         }
 164         return 0;
 165 }
 166
 167
 168 /*
 169  * Reads the lookup table from a WIM file.
 170  *
 171  * @fp:                 The FILE* for the WIM file.
 172  * @offset:             The offset of the lookup table resource.
 173  * @size:               The size of the lookup table resource.
 174  * @lookup_table_ret:   A pointer to a struct lookup_table structure into which the
 175  *                              lookup table will be returned.
 176  * @return:             True on success, false on failure.
 177  */
 178 int read_lookup_table(FILE *fp, u64 offset, u64 size,
 179                       struct lookup_table **table_ret)
 180 {
 181         size_t num_entries;
 182         u8     buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 183         int    ret;
 184         struct lookup_table *table;
 185         const u8 *p;
 186         struct lookup_table_entry *cur_entry;
 187
 188         DEBUG("Reading lookup table: offset %"PRIu64", size %"PRIu64"",
 189               offset, size);
 190
 191         if (fseeko(fp, offset, SEEK_SET) != 0) {
 192                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
 193                                  "lookup table", offset);
 194                 return WIMLIB_ERR_READ;
 195         }
 196
 197         num_entries = size / WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE;
 198         table = new_lookup_table(num_entries * 2 + 1);
 199         if (!table)
 200                 return WIMLIB_ERR_NOMEM;
 201
 202         while (num_entries--) {
 203                 if (fread(buf, 1, sizeof(buf), fp) != sizeof(buf)) {
 204                         if (feof(fp)) {
 205                                 ERROR("Unexpected EOF in WIM lookup table!");
 206                         } else {
 207                                 ERROR_WITH_ERRNO("Error reading WIM lookup "
 208                                                  "table");
 209                         }
 210                         ret = WIMLIB_ERR_READ;
 211                         goto out;
 212                 }
 213                 cur_entry = new_lookup_table_entry();
 214                 if (!cur_entry) {
 215                         ret = WIMLIB_ERR_NOMEM;
 216                         goto out;
 217                 }
 218
 219                 p = get_resource_entry(buf, &cur_entry->resource_entry);
 220                 p = get_u16(p, &cur_entry->part_number);
 221                 p = get_u32(p, &cur_entry->refcnt);
 222                 p = get_bytes(p, SHA1_HASH_SIZE, cur_entry->hash);
 223                 lookup_table_insert(table, cur_entry);
 224         }
 225         DEBUG("Done reading lookup table.");
 226         *table_ret = table;
 227         return 0;
 228 out:
 229         free_lookup_table(table);
 230         return ret;
 231 }
 232
 233
 234 /*
 235  * Writes a lookup table entry to the output file.
 236  */
 237 int write_lookup_table_entry(struct lookup_table_entry *lte, void *__out)
 238 {
 239         FILE *out;
 240         u8 buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 241         u8 *p;
 242
 243         out = __out;
 244
 245         /* do not write lookup table entries for empty files */
 246         if (lte->output_resource_entry.original_size == 0)
 247                 return 0;
 248
 249         /* Don't write entries that have not had file resources or metadata
 250          * resources written for them. */
 251         if (lte->out_refcnt == 0)
 252                 return 0;
 253
 254         if (lte->output_resource_entry.flags & WIM_RESHDR_FLAG_METADATA)
 255                 DEBUG("Writing metadata entry at %lu (orig size = %zu)",
 256                       ftello(out), lte->output_resource_entry.original_size);
 257
 258         p = put_resource_entry(buf, &lte->output_resource_entry);
 259         p = put_u16(p, lte->part_number);
 260         p = put_u32(p, lte->out_refcnt);
 261         p = put_bytes(p, SHA1_HASH_SIZE, lte->hash);
 262         if (fwrite(buf, 1, sizeof(buf), out) != sizeof(buf)) {
 263                 ERROR_WITH_ERRNO("Failed to write lookup table entry");
 264                 return WIMLIB_ERR_WRITE;
 265         }
 266         return 0;
 267 }
 268
 269
 270
 271 int zero_out_refcnts(struct lookup_table_entry *entry, void *ignore)
 272 {
 273         entry->out_refcnt = 0;
 274         return 0;
 275 }
 276
 277 void print_lookup_table_entry(struct lookup_table_entry *lte)
 278 {
 279         if (!lte) {
 280                 putchar('\n');
 281                 return;
 282         }
 283         printf("Offset            = %"PRIu64" bytes\n",
 284                lte->resource_entry.offset);
 285         printf("Size              = %"PRIu64" bytes\n",
 286                (u64)lte->resource_entry.size);
 287         printf("Original size     = %"PRIu64" bytes\n",
 288                lte->resource_entry.original_size);
 289         printf("Part Number       = %hu\n", lte->part_number);
 290         printf("Reference Count   = %u\n", lte->refcnt);
 291         printf("Hash              = 0x");
 292         print_hash(lte->hash);
 293         putchar('\n');
 294         printf("Flags             = ");
 295         u8 flags = lte->resource_entry.flags;
 296         if (flags & WIM_RESHDR_FLAG_COMPRESSED)
 297                 fputs("WIM_RESHDR_FLAG_COMPRESSED, ", stdout);
 298         if (flags & WIM_RESHDR_FLAG_FREE)
 299                 fputs("WIM_RESHDR_FLAG_FREE, ", stdout);
 300         if (flags & WIM_RESHDR_FLAG_METADATA)
 301                 fputs("WIM_RESHDR_FLAG_METADATA, ", stdout);
 302         if (flags & WIM_RESHDR_FLAG_SPANNED)
 303                 fputs("WIM_RESHDR_FLAG_SPANNED, ", stdout);
 304         putchar('\n');
 305         if (lte->file_on_disk && !lte->is_symlink)
 306                 printf("File on Disk      = `%s'\n", lte->file_on_disk);
 307         putchar('\n');
 308 }
 309
 310 static int do_print_lookup_table_entry(struct lookup_table_entry *lte,
 311                                        void *ignore)
 312 {
 313         print_lookup_table_entry(lte);
 314         return 0;
 315 }
 316
 317 /*
 318  * Prints the lookup table of a WIM file.
 319  */
 320 WIMLIBAPI void wimlib_print_lookup_table(WIMStruct *w)
 321 {
 322         for_lookup_table_entry(w->lookup_table,
 323                                do_print_lookup_table_entry,
 324                                NULL);
 325 }
 326
 327 /*
 328  * Looks up an entry in the lookup table.
 329  */
 330 struct lookup_table_entry *
 331 __lookup_resource(const struct lookup_table *table, const u8 hash[])
 332 {
 333         size_t i;
 334         struct lookup_table_entry *lte;
 335         struct hlist_node *pos;
 336
 337         i = *(size_t*)hash % table->capacity;
 338         hlist_for_each_entry(lte, pos, &table->array[i], hash_list)
 339                 if (hashes_equal(hash, lte->hash))
 340                         return lte;
 341         return NULL;
 342 }
 343
 344 /*
 345  * Finds the dentry, lookup table entry, and stream index for a WIM file stream,
 346  * given a path name.
 347  *
 348  * This is only for pre-resolved dentries.
 349  */
 350 int lookup_resource(WIMStruct *w, const char *path,
 351                     int lookup_flags,
 352                     struct dentry **dentry_ret,
 353                     struct lookup_table_entry **lte_ret,
 354                     unsigned *stream_idx_ret)
 355 {
 356         struct dentry *dentry;
 357         struct lookup_table_entry *lte;
 358         unsigned stream_idx;
 359         dentry = get_dentry(w, path);
 360         if (!dentry)
 361                 return -ENOENT;
 362
 363         wimlib_assert(dentry->resolved);
 364
 365         lte = dentry->lte;
 366         if (!(lookup_flags & LOOKUP_FLAG_DIRECTORY_OK)
 367               && dentry_is_directory(dentry))
 368                 return -EISDIR;
 369         stream_idx = 0;
 370         if (lookup_flags & LOOKUP_FLAG_ADS_OK) {
 371                 const char *stream_name = path_stream_name(path);
 372                 if (stream_name) {
 373                         size_t stream_name_len = strlen(stream_name);
 374                         for (u16 i = 0; i < dentry->num_ads; i++) {
 375                                 if (ads_entry_has_name(&dentry->ads_entries[i],
 376                                                        stream_name,
 377                                                        stream_name_len))
 378                                 {
 379                                         stream_idx = i + 1;
 380                                         lte = dentry->ads_entries[i].lte;
 381                                         goto out;
 382                                 }
 383                         }
 384                         return -ENOENT;
 385                 }
 386         }
 387 out:
 388         if (dentry_ret)
 389                 *dentry_ret = dentry;
 390         if (lte_ret)
 391                 *lte_ret = lte;
 392         if (stream_idx_ret)
 393                 *stream_idx_ret = stream_idx;
 394         return 0;
 395 }
 396
 397 /* Resolve a dentry's lookup table entries
 398  *
 399  * This replaces the SHA1 hash fields (which are used to lookup an entry in the
 400  * lookup table) with pointers directly to the lookup table entries.  A circular
 401  * linked list of streams sharing the same lookup table entry is created.
 402  *
 403  * This function always succeeds; unresolved lookup table entries are given a
 404  * NULL pointer.
 405  */
 406 int dentry_resolve_ltes(struct dentry *dentry, void *__table)
 407 {
 408         struct lookup_table *table = __table;
 409         struct lookup_table_entry *lte;
 410
 411         if (dentry->resolved)
 412                 return 0;
 413
 414         /* Resolve the default file stream */
 415         lte = __lookup_resource(table, dentry->hash);
 416         if (lte)
 417                 list_add(&dentry->lte_group_list.list, &lte->lte_group_list);
 418         else
 419                 INIT_LIST_HEAD(&dentry->lte_group_list.list);
 420         dentry->lte = lte;
 421         dentry->lte_group_list.type = STREAM_TYPE_NORMAL;
 422         dentry->resolved = true;
 423
 424         /* Resolve the alternate data streams */
 425         if (dentry->ads_entries_status != ADS_ENTRIES_USER) {
 426                 for (u16 i = 0; i < dentry->num_ads; i++) {
 427                         struct ads_entry *cur_entry = &dentry->ads_entries[i];
 428
 429                         lte = __lookup_resource(table, cur_entry->hash);
 430                         if (lte)
 431                                 list_add(&cur_entry->lte_group_list.list,
 432                                          &lte->lte_group_list);
 433                         else
 434                                 INIT_LIST_HEAD(&cur_entry->lte_group_list.list);
 435                         cur_entry->lte = lte;
 436                         cur_entry->lte_group_list.type = STREAM_TYPE_ADS;
 437                 }
 438         }
 439         return 0;
 440 }
 441
 442 struct lookup_table_entry *
 443 dentry_first_lte(const struct dentry *dentry, const struct lookup_table *table)
 444 {
 445         if (dentry->resolved)
 446                 return dentry_first_lte_resolved(dentry);
 447         else
 448                 return dentry_first_lte_unresolved(dentry, table);
 449 }
 450