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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                 if (lte->resource_location != RESOURCE_IN_WIM &&
  79                     lte->resource_location != RESOURCE_NONEXISTENT)
  80                         FREE(lte->file_on_disk);
  81                 FREE(lte);
  82         }
  83 }
  84
  85 static int do_free_lookup_table_entry(struct lookup_table_entry *entry,
  86                                       void *ignore)
  87 {
  88         free_lookup_table_entry(entry);
  89         return 0;
  90 }
  91
  92
  93 void free_lookup_table(struct lookup_table *table)
  94 {
  95         DEBUG("Freeing lookup table");
  96         if (table) {
  97                 if (table->array) {
  98                         for_lookup_table_entry(table,
  99                                                do_free_lookup_table_entry,
 100                                                NULL);
 101                         FREE(table->array);
 102                 }
 103                 FREE(table);
 104         }
 105 }
 106
 107 /*
 108  * Inserts an entry into the lookup table.
 109  *
 110  * @table:      A pointer to the lookup table.
 111  * @entry:      A pointer to the entry to insert.
 112  */
 113 void lookup_table_insert(struct lookup_table *table,
 114                          struct lookup_table_entry *lte)
 115 {
 116         size_t i = lte->hash_short % table->capacity;
 117         hlist_add_head(&lte->hash_list, &table->array[i]);
 118
 119         /* XXX Make the table grow when too many entries have been inserted. */
 120         table->num_entries++;
 121 }
 122
 123
 124
 125 /* Decrements the reference count for the lookup table entry @lte.  If its
 126  * reference count reaches 0, it is unlinked from the lookup table.  If,
 127  * furthermore, the entry has no opened file descriptors associated with it, the
 128  * entry is freed.  */
 129 struct lookup_table_entry *
 130 lte_decrement_refcnt(struct lookup_table_entry *lte, struct lookup_table *table)
 131 {
 132         if (lte) {
 133                 wimlib_assert(lte->refcnt);
 134                 if (--lte->refcnt == 0) {
 135                         lookup_table_unlink(table, lte);
 136                 #ifdef WITH_FUSE
 137                         if (lte->num_opened_fds == 0)
 138                 #endif
 139                         {
 140                                 free_lookup_table_entry(lte);
 141                                 lte = NULL;
 142                         }
 143                 }
 144         }
 145         return lte;
 146 }
 147
 148 /*
 149  * Calls a function on all the entries in the lookup table.  Stop early and
 150  * return nonzero if any call to the function returns nonzero.
 151  */
 152 int for_lookup_table_entry(struct lookup_table *table,
 153                            int (*visitor)(struct lookup_table_entry *, void *),
 154                            void *arg)
 155 {
 156         struct lookup_table_entry *lte;
 157         struct hlist_node *pos, *tmp;
 158         int ret;
 159
 160         for (size_t i = 0; i < table->capacity; i++) {
 161                 hlist_for_each_entry_safe(lte, pos, tmp, &table->array[i],
 162                                           hash_list)
 163                 {
 164                         ret = visitor(lte, arg);
 165                         if (ret != 0)
 166                                 return ret;
 167                 }
 168         }
 169         return 0;
 170 }
 171
 172
 173 /*
 174  * Reads the lookup table from a WIM file.
 175  */
 176 int read_lookup_table(WIMStruct *w)
 177 {
 178         u64    num_entries;
 179         u8     buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 180         int    ret;
 181         struct lookup_table *table;
 182
 183         DEBUG("Reading lookup table: offset %"PRIu64", size %"PRIu64"",
 184               w->hdr.lookup_table_res_entry.offset,
 185               w->hdr.lookup_table_res_entry.original_size);
 186
 187         if (fseeko(w->fp, w->hdr.lookup_table_res_entry.offset, SEEK_SET) != 0) {
 188                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
 189                                  "lookup table",
 190                                  w->hdr.lookup_table_res_entry.offset);
 191                 return WIMLIB_ERR_READ;
 192         }
 193
 194         num_entries = w->hdr.lookup_table_res_entry.original_size /
 195                       WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE;
 196         table = new_lookup_table(num_entries * 2 + 1);
 197         if (!table)
 198                 return WIMLIB_ERR_NOMEM;
 199
 200         while (num_entries--) {
 201                 const u8 *p;
 202                 struct lookup_table_entry *cur_entry, *duplicate_entry;
 203
 204                 if (fread(buf, 1, sizeof(buf), w->fp) != sizeof(buf)) {
 205                         if (feof(w->fp)) {
 206                                 ERROR("Unexpected EOF in WIM lookup table!");
 207                         } else {
 208                                 ERROR_WITH_ERRNO("Error reading WIM lookup "
 209                                                  "table");
 210                         }
 211                         ret = WIMLIB_ERR_READ;
 212                         goto out;
 213                 }
 214                 cur_entry = new_lookup_table_entry();
 215                 if (!cur_entry) {
 216                         ret = WIMLIB_ERR_NOMEM;
 217                         goto out;
 218                 }
 219                 cur_entry->wim = w;
 220                 cur_entry->resource_location = RESOURCE_IN_WIM;
 221
 222                 p = get_resource_entry(buf, &cur_entry->resource_entry);
 223                 p = get_u16(p, &cur_entry->part_number);
 224                 p = get_u32(p, &cur_entry->refcnt);
 225                 p = get_bytes(p, SHA1_HASH_SIZE, cur_entry->hash);
 226
 227                 if (is_zero_hash(cur_entry->hash)) {
 228                         ERROR("The WIM lookup table contains an entry with a "
 229                               "SHA1 message digest of all 0's");
 230                         ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
 231                         FREE(cur_entry);
 232                         goto out;
 233                 }
 234
 235                 duplicate_entry = __lookup_resource(table, cur_entry->hash);
 236                 if (duplicate_entry) {
 237                         ERROR("The WIM lookup table contains two entries with the "
 238                               "same SHA1 message digest!");
 239                         ERROR("The first entry is:");
 240                         print_lookup_table_entry(duplicate_entry);
 241                         ERROR("The second entry is:");
 242                         print_lookup_table_entry(cur_entry);
 243                         ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
 244                         FREE(cur_entry);
 245                         goto out;
 246                 }
 247                 lookup_table_insert(table, cur_entry);
 248
 249                 if (!(cur_entry->resource_entry.flags & WIM_RESHDR_FLAG_COMPRESSED)
 250                     && (cur_entry->resource_entry.size !=
 251                       cur_entry->resource_entry.original_size))
 252                 {
 253                         ERROR("Found uncompressed resource with original size "
 254                               "not the same as compressed size");
 255                         ERROR("The lookup table entry for the resource is as follows:");
 256                         print_lookup_table_entry(cur_entry);
 257                         ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
 258                         goto out;
 259                 }
 260         }
 261         DEBUG("Done reading lookup table.");
 262         w->lookup_table = table;
 263         return 0;
 264 out:
 265         free_lookup_table(table);
 266         return ret;
 267 }
 268
 269
 270 /*
 271  * Writes a lookup table entry to the output file.
 272  */
 273 int write_lookup_table_entry(struct lookup_table_entry *lte, void *__out)
 274 {
 275         FILE *out;
 276         u8 buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 277         u8 *p;
 278
 279         out = __out;
 280
 281         /* Don't write entries that have not had file resources or metadata
 282          * resources written for them. */
 283         if (lte->out_refcnt == 0)
 284                 return 0;
 285
 286         if (lte->output_resource_entry.flags & WIM_RESHDR_FLAG_METADATA)
 287                 DEBUG("Writing metadata entry at %lu (orig size = %zu)",
 288                       ftello(out), lte->output_resource_entry.original_size);
 289
 290         p = put_resource_entry(buf, &lte->output_resource_entry);
 291         p = put_u16(p, lte->part_number);
 292         p = put_u32(p, lte->out_refcnt);
 293         p = put_bytes(p, SHA1_HASH_SIZE, lte->hash);
 294         if (fwrite(buf, 1, sizeof(buf), out) != sizeof(buf)) {
 295                 ERROR_WITH_ERRNO("Failed to write lookup table entry");
 296                 return WIMLIB_ERR_WRITE;
 297         }
 298         return 0;
 299 }
 300
 301
 302
 303 int zero_out_refcnts(struct lookup_table_entry *entry, void *ignore)
 304 {
 305         entry->out_refcnt = 0;
 306         return 0;
 307 }
 308
 309 void print_lookup_table_entry(const struct lookup_table_entry *lte)
 310 {
 311         if (!lte) {
 312                 putchar('\n');
 313                 return;
 314         }
 315         printf("Offset            = %"PRIu64" bytes\n",
 316                lte->resource_entry.offset);
 317         printf("Size              = %"PRIu64" bytes\n",
 318                (u64)lte->resource_entry.size);
 319         printf("Original size     = %"PRIu64" bytes\n",
 320                lte->resource_entry.original_size);
 321         printf("Part Number       = %hu\n", lte->part_number);
 322         printf("Reference Count   = %u\n", lte->refcnt);
 323         printf("Hash              = 0x");
 324         print_hash(lte->hash);
 325         putchar('\n');
 326         printf("Flags             = ");
 327         u8 flags = lte->resource_entry.flags;
 328         if (flags & WIM_RESHDR_FLAG_COMPRESSED)
 329                 fputs("WIM_RESHDR_FLAG_COMPRESSED, ", stdout);
 330         if (flags & WIM_RESHDR_FLAG_FREE)
 331                 fputs("WIM_RESHDR_FLAG_FREE, ", stdout);
 332         if (flags & WIM_RESHDR_FLAG_METADATA)
 333                 fputs("WIM_RESHDR_FLAG_METADATA, ", stdout);
 334         if (flags & WIM_RESHDR_FLAG_SPANNED)
 335                 fputs("WIM_RESHDR_FLAG_SPANNED, ", stdout);
 336         putchar('\n');
 337         switch (lte->resource_location) {
 338         case RESOURCE_IN_WIM:
 339                 if (lte->wim->filename) {
 340                         printf("WIM file          = `%s'\n",
 341                                lte->wim->filename);
 342                 }
 343                 break;
 344         case RESOURCE_IN_FILE_ON_DISK:
 345                 printf("File on Disk      = `%s'\n", lte->file_on_disk);
 346                 break;
 347         case RESOURCE_IN_STAGING_FILE:
 348                 printf("Staging File      = `%s'\n", lte->staging_file_name);
 349                 break;
 350         default:
 351                 break;
 352         }
 353         putchar('\n');
 354 }
 355
 356 static int do_print_lookup_table_entry(struct lookup_table_entry *lte,
 357                                        void *ignore)
 358 {
 359         print_lookup_table_entry(lte);
 360         return 0;
 361 }
 362
 363 /*
 364  * Prints the lookup table of a WIM file.
 365  */
 366 WIMLIBAPI void wimlib_print_lookup_table(WIMStruct *w)
 367 {
 368         for_lookup_table_entry(w->lookup_table,
 369                                do_print_lookup_table_entry,
 370                                NULL);
 371 }
 372
 373 /*
 374  * Looks up an entry in the lookup table.
 375  */
 376 struct lookup_table_entry *
 377 __lookup_resource(const struct lookup_table *table, const u8 hash[])
 378 {
 379         size_t i;
 380         struct lookup_table_entry *lte;
 381         struct hlist_node *pos;
 382
 383         i = *(size_t*)hash % table->capacity;
 384         hlist_for_each_entry(lte, pos, &table->array[i], hash_list)
 385                 if (hashes_equal(hash, lte->hash))
 386                         return lte;
 387         return NULL;
 388 }
 389
 390 /*
 391  * Finds the dentry, lookup table entry, and stream index for a WIM file stream,
 392  * given a path name.
 393  *
 394  * This is only for pre-resolved dentries.
 395  */
 396 int lookup_resource(WIMStruct *w, const char *path,
 397                     int lookup_flags,
 398                     struct dentry **dentry_ret,
 399                     struct lookup_table_entry **lte_ret,
 400                     unsigned *stream_idx_ret)
 401 {
 402         struct dentry *dentry;
 403         struct lookup_table_entry *lte;
 404         unsigned stream_idx;
 405         const char *stream_name = NULL;
 406         char *p = NULL;
 407
 408         if (lookup_flags & LOOKUP_FLAG_ADS_OK) {
 409                 stream_name = path_stream_name(path);
 410                 if (stream_name) {
 411                         p = (char*)stream_name - 1;
 412                         *p = '\0';
 413                 }
 414         }
 415
 416         dentry = get_dentry(w, path);
 417         if (p)
 418                 *p = ':';
 419         if (!dentry)
 420                 return -ENOENT;
 421
 422         wimlib_assert(dentry->resolved);
 423
 424         lte = dentry->lte;
 425         if (!(lookup_flags & LOOKUP_FLAG_DIRECTORY_OK)
 426               && dentry_is_directory(dentry))
 427                 return -EISDIR;
 428         stream_idx = 0;
 429         if (stream_name) {
 430                 size_t stream_name_len = strlen(stream_name);
 431                 for (u16 i = 0; i < dentry->num_ads; i++) {
 432                         if (ads_entry_has_name(&dentry->ads_entries[i],
 433                                                stream_name,
 434                                                stream_name_len))
 435                         {
 436                                 stream_idx = i + 1;
 437                                 lte = dentry->ads_entries[i].lte;
 438                                 goto out;
 439                         }
 440                 }
 441                 return -ENOENT;
 442         }
 443 out:
 444         if (dentry_ret)
 445                 *dentry_ret = dentry;
 446         if (lte_ret)
 447                 *lte_ret = lte;
 448         if (stream_idx_ret)
 449                 *stream_idx_ret = stream_idx;
 450         return 0;
 451 }
 452
 453 /* Resolve a dentry's lookup table entries
 454  *
 455  * This replaces the SHA1 hash fields (which are used to lookup an entry in the
 456  * lookup table) with pointers directly to the lookup table entries.  A circular
 457  * linked list of streams sharing the same lookup table entry is created.
 458  *
 459  * This function always succeeds; unresolved lookup table entries are given a
 460  * NULL pointer.
 461  */
 462 int dentry_resolve_ltes(struct dentry *dentry, void *__table)
 463 {
 464         struct lookup_table *table = __table;
 465         struct lookup_table_entry *lte;
 466
 467         if (dentry->resolved)
 468                 return 0;
 469
 470         /* Resolve the default file stream */
 471         lte = __lookup_resource(table, dentry->hash);
 472         if (lte)
 473                 list_add(&dentry->lte_group_list.list, &lte->lte_group_list);
 474         else
 475                 INIT_LIST_HEAD(&dentry->lte_group_list.list);
 476         dentry->lte = lte;
 477         dentry->lte_group_list.type = STREAM_TYPE_NORMAL;
 478         dentry->resolved = true;
 479
 480         /* Resolve the alternate data streams */
 481         if (dentry->ads_entries_status != ADS_ENTRIES_USER) {
 482                 for (u16 i = 0; i < dentry->num_ads; i++) {
 483                         struct ads_entry *cur_entry = &dentry->ads_entries[i];
 484
 485                         lte = __lookup_resource(table, cur_entry->hash);
 486                         if (lte)
 487                                 list_add(&cur_entry->lte_group_list.list,
 488                                          &lte->lte_group_list);
 489                         else
 490                                 INIT_LIST_HEAD(&cur_entry->lte_group_list.list);
 491                         cur_entry->lte = lte;
 492                         cur_entry->lte_group_list.type = STREAM_TYPE_ADS;
 493                 }
 494         }
 495         return 0;
 496 }
 497
 498 /* Return the lookup table entry for the unnamed data stream of a dentry, or
 499  * NULL if there is none.
 500  *
 501  * You'd think this would be easier than it actually is, since the unnamed data
 502  * stream should be the one referenced from the dentry itself.  Alas, if there
 503  * are named data streams, Microsoft's "imagex.exe" program will put the unnamed
 504  * data stream in one of the alternate data streams instead of inside the
 505  * dentry.  So we need to check the alternate data streams too.
 506  *
 507  * Also, note that a dentry may appear to have than one unnamed stream, but if
 508  * the SHA1 message digest is all 0's then the corresponding stream does not
 509  * really "count" (this is the case for the dentry's own file stream when the
 510  * file stream that should be there is actually in one of the alternate stream
 511  * entries.).  This is despite the fact that we may need to extract such a
 512  * missing entry as an empty file or empty named data stream.
 513  */
 514 struct lookup_table_entry *
 515 dentry_unnamed_lte(const struct dentry *dentry,
 516                    const struct lookup_table *table)
 517 {
 518         if (dentry->resolved)
 519                 return dentry_unnamed_lte_resolved(dentry);
 520         else
 521                 return dentry_unnamed_lte_unresolved(dentry, table);
 522 }
 523