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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 General Public License as published by the Free
  15  * Software Foundation; either version 3 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 General Public License for more
  21  * details.
  22  *
  23  * You should have received a copy of the GNU 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 #ifdef WITH_FUSE
  33 #include <unistd.h>
  34 #endif
  35
  36 struct lookup_table *new_lookup_table(size_t capacity)
  37 {
  38         struct lookup_table *table;
  39         struct hlist_head *array;
  40
  41         table = MALLOC(sizeof(struct lookup_table));
  42         if (!table)
  43                 goto err;
  44         array = CALLOC(capacity, sizeof(array[0]));
  45         if (!array) {
  46                 FREE(table);
  47                 goto err;
  48         }
  49         table->num_entries = 0;
  50         table->capacity = capacity;
  51         table->array = array;
  52         return table;
  53 err:
  54         ERROR("Failed to allocate memory for lookup table with capacity %zu",
  55               capacity);
  56         return NULL;
  57 }
  58
  59 struct lookup_table_entry *new_lookup_table_entry()
  60 {
  61         struct lookup_table_entry *lte;
  62
  63         lte = CALLOC(1, sizeof(struct lookup_table_entry));
  64         if (lte) {
  65                 lte->part_number  = 1;
  66                 lte->refcnt       = 1;
  67         } else {
  68                 ERROR("Out of memory (tried to allocate %zu bytes for "
  69                       "lookup table entry)",
  70                       sizeof(struct lookup_table_entry));
  71         }
  72         return lte;
  73 }
  74
  75 struct lookup_table_entry *
  76 clone_lookup_table_entry(const struct lookup_table_entry *old)
  77 {
  78         struct lookup_table_entry *new;
  79
  80         new = MALLOC(sizeof(*new));
  81         if (!new)
  82                 return NULL;
  83
  84         memcpy(new, old, sizeof(*old));
  85         new->extracted_file = NULL;
  86         switch (new->resource_location) {
  87         case RESOURCE_IN_STAGING_FILE:
  88         case RESOURCE_IN_FILE_ON_DISK:
  89                 wimlib_assert((void*)&old->file_on_disk ==
  90                               (void*)&old->staging_file_name);
  91                 new->staging_file_name = STRDUP(old->staging_file_name);
  92                 if (!new->staging_file_name)
  93                         goto out_free;
  94                 break;
  95         case RESOURCE_IN_ATTACHED_BUFFER:
  96                 new->attached_buffer = MALLOC(wim_resource_size(old));
  97                 if (!new->attached_buffer)
  98                         goto out_free;
  99                 memcpy(new->attached_buffer, old->attached_buffer,
 100                        wim_resource_size(old));
 101                 break;
 102 #ifdef WITH_NTFS_3G
 103         case RESOURCE_IN_NTFS_VOLUME:
 104                 if (old->ntfs_loc) {
 105                         struct ntfs_location *loc;
 106                         loc = MALLOC(sizeof(*loc));
 107                         if (!loc)
 108                                 goto out_free;
 109                         memcpy(loc, old->ntfs_loc, sizeof(*loc));
 110                         loc->path_utf8 = NULL;
 111                         loc->stream_name_utf16 = NULL;
 112                         new->ntfs_loc = loc;
 113                         loc->path_utf8 = STRDUP(old->ntfs_loc->path_utf8);
 114                         if (!loc->path_utf8)
 115                                 goto out_free;
 116                         loc->stream_name_utf16 = MALLOC(loc->stream_name_utf16_num_chars * 2);
 117                         if (!loc->stream_name_utf16)
 118                                 goto out_free;
 119                         memcpy(loc->stream_name_utf16,
 120                                old->ntfs_loc->stream_name_utf16,
 121                                loc->stream_name_utf16_num_chars * 2);
 122                 }
 123                 break;
 124 #endif
 125         default:
 126                 break;
 127         }
 128         return new;
 129 out_free:
 130         free_lookup_table_entry(new);
 131         return NULL;
 132 }
 133
 134 void free_lookup_table_entry(struct lookup_table_entry *lte)
 135 {
 136         if (lte) {
 137                 switch (lte->resource_location) {
 138                 case RESOURCE_IN_STAGING_FILE:
 139                 case RESOURCE_IN_ATTACHED_BUFFER:
 140                 case RESOURCE_IN_FILE_ON_DISK:
 141                         wimlib_assert(((void*)&lte->file_on_disk ==
 142                                       (void*)&lte->staging_file_name)
 143                                       && ((void*)&lte->file_on_disk ==
 144                                       (void*)&lte->attached_buffer));
 145                         FREE(lte->file_on_disk);
 146                         break;
 147 #ifdef WITH_NTFS_3G
 148                 case RESOURCE_IN_NTFS_VOLUME:
 149                         if (lte->ntfs_loc) {
 150                                 FREE(lte->ntfs_loc->path_utf8);
 151                                 FREE(lte->ntfs_loc->stream_name_utf16);
 152                                 FREE(lte->ntfs_loc);
 153                         }
 154                         break;
 155 #endif
 156                 default:
 157                         break;
 158                 }
 159                 FREE(lte);
 160         }
 161 }
 162
 163 static int do_free_lookup_table_entry(struct lookup_table_entry *entry,
 164                                       void *ignore)
 165 {
 166         free_lookup_table_entry(entry);
 167         return 0;
 168 }
 169
 170
 171 void free_lookup_table(struct lookup_table *table)
 172 {
 173         DEBUG2("Freeing lookup table");
 174         if (table) {
 175                 if (table->array) {
 176                         for_lookup_table_entry(table,
 177                                                do_free_lookup_table_entry,
 178                                                NULL);
 179                         FREE(table->array);
 180                 }
 181                 FREE(table);
 182         }
 183 }
 184
 185 /*
 186  * Inserts an entry into the lookup table.
 187  *
 188  * @table:      A pointer to the lookup table.
 189  * @entry:      A pointer to the entry to insert.
 190  */
 191 void lookup_table_insert(struct lookup_table *table,
 192                          struct lookup_table_entry *lte)
 193 {
 194         size_t i = lte->hash_short % table->capacity;
 195         hlist_add_head(&lte->hash_list, &table->array[i]);
 196
 197         /* XXX Make the table grow when too many entries have been inserted. */
 198         table->num_entries++;
 199 }
 200
 201 static void finalize_lte(struct lookup_table_entry *lte)
 202 {
 203         #ifdef WITH_FUSE
 204         if (lte->resource_location == RESOURCE_IN_STAGING_FILE) {
 205                 unlink(lte->staging_file_name);
 206                 wimlib_assert(lte->staging_list.next);
 207                 wimlib_assert(lte->staging_list.prev);
 208                 list_del(&lte->staging_list);
 209         }
 210         #endif
 211         free_lookup_table_entry(lte);
 212 }
 213
 214 /* Decrements the reference count for the lookup table entry @lte.  If its
 215  * reference count reaches 0, it is unlinked from the lookup table.  If,
 216  * furthermore, the entry has no opened file descriptors associated with it, the
 217  * entry is freed.  */
 218 void lte_decrement_refcnt(struct lookup_table_entry *lte,
 219                           struct lookup_table *table)
 220 {
 221         wimlib_assert(lte != NULL);
 222         wimlib_assert(lte->refcnt != 0);
 223         if (--lte->refcnt == 0) {
 224                 lookup_table_unlink(table, lte);
 225         #ifdef WITH_FUSE
 226                 if (lte->num_opened_fds == 0)
 227         #endif
 228                         finalize_lte(lte);
 229         }
 230 }
 231
 232 #ifdef WITH_FUSE
 233 void lte_decrement_num_opened_fds(struct lookup_table_entry *lte)
 234 {
 235         wimlib_assert(lte != NULL);
 236         wimlib_assert(lte->num_opened_fds != 0);
 237         if (atomic_dec(&lte->num_opened_fds) == 0 && lte->refcnt == 0)
 238                 finalize_lte(lte);
 239 }
 240 #endif
 241
 242 /*
 243  * Calls a function on all the entries in the lookup table.  Stop early and
 244  * return nonzero if any call to the function returns nonzero.
 245  */
 246 int for_lookup_table_entry(struct lookup_table *table,
 247                            int (*visitor)(struct lookup_table_entry *, void *),
 248                            void *arg)
 249 {
 250         struct lookup_table_entry *lte;
 251         struct hlist_node *pos, *tmp;
 252         int ret;
 253
 254         for (size_t i = 0; i < table->capacity; i++) {
 255                 hlist_for_each_entry_safe(lte, pos, tmp, &table->array[i],
 256                                           hash_list)
 257                 {
 258                         ret = visitor(lte, arg);
 259                         if (ret != 0)
 260                                 return ret;
 261                 }
 262         }
 263         return 0;
 264 }
 265
 266
 267 /*
 268  * Reads the lookup table from a WIM file.
 269  */
 270 int read_lookup_table(WIMStruct *w)
 271 {
 272         u64    num_entries;
 273         u8     buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 274         int    ret;
 275         struct lookup_table *table;
 276         struct lookup_table_entry *cur_entry = NULL, *duplicate_entry;
 277
 278         DEBUG("Reading lookup table: offset %"PRIu64", size %"PRIu64"",
 279               w->hdr.lookup_table_res_entry.offset,
 280               w->hdr.lookup_table_res_entry.original_size);
 281
 282         if (fseeko(w->fp, w->hdr.lookup_table_res_entry.offset, SEEK_SET) != 0)
 283         {
 284                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
 285                                  "lookup table",
 286                                  w->hdr.lookup_table_res_entry.offset);
 287                 return WIMLIB_ERR_READ;
 288         }
 289
 290         num_entries = w->hdr.lookup_table_res_entry.original_size /
 291                       WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE;
 292         table = new_lookup_table(num_entries * 2 + 1);
 293         if (!table)
 294                 return WIMLIB_ERR_NOMEM;
 295
 296         while (num_entries--) {
 297                 const u8 *p;
 298
 299                 if (fread(buf, 1, sizeof(buf), w->fp) != sizeof(buf)) {
 300                         if (feof(w->fp)) {
 301                                 ERROR("Unexpected EOF in WIM lookup table!");
 302                         } else {
 303                                 ERROR_WITH_ERRNO("Error reading WIM lookup "
 304                                                  "table");
 305                         }
 306                         ret = WIMLIB_ERR_READ;
 307                         goto out;
 308                 }
 309                 cur_entry = new_lookup_table_entry();
 310                 if (!cur_entry) {
 311                         ret = WIMLIB_ERR_NOMEM;
 312                         goto out;
 313                 }
 314                 cur_entry->wim = w;
 315                 cur_entry->resource_location = RESOURCE_IN_WIM;
 316
 317                 p = get_resource_entry(buf, &cur_entry->resource_entry);
 318                 p = get_u16(p, &cur_entry->part_number);
 319                 p = get_u32(p, &cur_entry->refcnt);
 320                 p = get_bytes(p, SHA1_HASH_SIZE, cur_entry->hash);
 321
 322                 if (cur_entry->part_number != w->hdr.part_number) {
 323                         ERROR("A lookup table entry in part %hu of the WIM "
 324                               "points to part %hu",
 325                               w->hdr.part_number, cur_entry->part_number);
 326                         ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
 327                         goto out_free_cur_entry;
 328                 }
 329
 330                 if (is_zero_hash(cur_entry->hash)) {
 331                         ERROR("The WIM lookup table contains an entry with a "
 332                               "SHA1 message digest of all 0's");
 333                         ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
 334                         goto out_free_cur_entry;
 335                 }
 336
 337                 /* Ordinarily, no two streams should share the same SHA1 message
 338                  * digest.  However, this constraint can be broken for metadata
 339                  * resources--- two identical images will have the same metadata
 340                  * resource, but their lookup table entries are not shared. */
 341                 duplicate_entry = __lookup_resource(table, cur_entry->hash);
 342                 if (duplicate_entry
 343                     && !((duplicate_entry->resource_entry.flags & WIM_RESHDR_FLAG_METADATA)
 344                           && cur_entry->resource_entry.flags & WIM_RESHDR_FLAG_METADATA))
 345                 {
 346                         ERROR("The WIM lookup table contains two entries with the "
 347                               "same SHA1 message digest!");
 348                         ERROR("The first entry is:");
 349                         print_lookup_table_entry(duplicate_entry);
 350                         ERROR("The second entry is:");
 351                         print_lookup_table_entry(cur_entry);
 352                         ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
 353                         goto out_free_cur_entry;
 354                 }
 355
 356                 if (!(cur_entry->resource_entry.flags & WIM_RESHDR_FLAG_COMPRESSED)
 357                     && (cur_entry->resource_entry.size !=
 358                         cur_entry->resource_entry.original_size))
 359                 {
 360                         ERROR("Found uncompressed resource with original size "
 361                               "not the same as compressed size");
 362                         ERROR("The lookup table entry for the resource is as follows:");
 363                         print_lookup_table_entry(cur_entry);
 364                         ret = WIMLIB_ERR_INVALID_LOOKUP_TABLE_ENTRY;
 365                         goto out_free_cur_entry;
 366                 }
 367                 lookup_table_insert(table, cur_entry);
 368
 369         }
 370         DEBUG("Done reading lookup table.");
 371         w->lookup_table = table;
 372         return 0;
 373 out_free_cur_entry:
 374         FREE(cur_entry);
 375 out:
 376         free_lookup_table(table);
 377         return ret;
 378 }
 379
 380
 381 /*
 382  * Writes a lookup table entry to the output file.
 383  */
 384 int write_lookup_table_entry(struct lookup_table_entry *lte, void *__out)
 385 {
 386         FILE *out;
 387         u8 buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 388         u8 *p;
 389
 390         out = __out;
 391
 392         /* Don't write entries that have not had file resources or metadata
 393          * resources written for them. */
 394         if (lte->out_refcnt == 0)
 395                 return 0;
 396
 397         if (lte->output_resource_entry.flags & WIM_RESHDR_FLAG_METADATA)
 398                 DEBUG("Writing metadata entry at %lu (orig size = %zu)",
 399                       ftello(out), lte->output_resource_entry.original_size);
 400
 401         p = put_resource_entry(buf, &lte->output_resource_entry);
 402         p = put_u16(p, lte->part_number);
 403         p = put_u32(p, lte->out_refcnt);
 404         p = put_bytes(p, SHA1_HASH_SIZE, lte->hash);
 405         if (fwrite(buf, 1, sizeof(buf), out) != sizeof(buf)) {
 406                 ERROR_WITH_ERRNO("Failed to write lookup table entry");
 407                 return WIMLIB_ERR_WRITE;
 408         }
 409         return 0;
 410 }
 411
 412
 413 int lte_zero_real_refcnt(struct lookup_table_entry *lte, void *ignore)
 414 {
 415         lte->real_refcnt = 0;
 416         return 0;
 417 }
 418
 419 int lte_zero_out_refcnt(struct lookup_table_entry *lte, void *ignore)
 420 {
 421         lte->out_refcnt = 0;
 422         return 0;
 423 }
 424
 425 int lte_zero_extracted_file(struct lookup_table_entry *lte, void *ignore)
 426 {
 427         lte->extracted_file = NULL;
 428         return 0;
 429 }
 430
 431 int lte_free_extracted_file(struct lookup_table_entry *lte, void *ignore)
 432 {
 433         if (lte->extracted_file != NULL) {
 434                 FREE(lte->extracted_file);
 435                 lte->extracted_file = NULL;
 436         }
 437         return 0;
 438 }
 439
 440 void print_lookup_table_entry(const struct lookup_table_entry *lte)
 441 {
 442         if (!lte) {
 443                 putchar('\n');
 444                 return;
 445         }
 446         printf("Offset            = %"PRIu64" bytes\n",
 447                lte->resource_entry.offset);
 448         printf("Size              = %"PRIu64" bytes\n",
 449                (u64)lte->resource_entry.size);
 450         printf("Original size     = %"PRIu64" bytes\n",
 451                lte->resource_entry.original_size);
 452         printf("Part Number       = %hu\n", lte->part_number);
 453         printf("Reference Count   = %u\n", lte->refcnt);
 454         printf("Hash              = 0x");
 455         print_hash(lte->hash);
 456         putchar('\n');
 457         printf("Flags             = ");
 458         u8 flags = lte->resource_entry.flags;
 459         if (flags & WIM_RESHDR_FLAG_COMPRESSED)
 460                 fputs("WIM_RESHDR_FLAG_COMPRESSED, ", stdout);
 461         if (flags & WIM_RESHDR_FLAG_FREE)
 462                 fputs("WIM_RESHDR_FLAG_FREE, ", stdout);
 463         if (flags & WIM_RESHDR_FLAG_METADATA)
 464                 fputs("WIM_RESHDR_FLAG_METADATA, ", stdout);
 465         if (flags & WIM_RESHDR_FLAG_SPANNED)
 466                 fputs("WIM_RESHDR_FLAG_SPANNED, ", stdout);
 467         putchar('\n');
 468         switch (lte->resource_location) {
 469         case RESOURCE_IN_WIM:
 470                 if (lte->wim->filename) {
 471                         printf("WIM file          = `%s'\n",
 472                                lte->wim->filename);
 473                 }
 474                 break;
 475         case RESOURCE_IN_FILE_ON_DISK:
 476                 printf("File on Disk      = `%s'\n", lte->file_on_disk);
 477                 break;
 478         case RESOURCE_IN_STAGING_FILE:
 479                 printf("Staging File      = `%s'\n", lte->staging_file_name);
 480                 break;
 481         default:
 482                 break;
 483         }
 484         putchar('\n');
 485 }
 486
 487 static int do_print_lookup_table_entry(struct lookup_table_entry *lte,
 488                                        void *ignore)
 489 {
 490         print_lookup_table_entry(lte);
 491         return 0;
 492 }
 493
 494 /*
 495  * Prints the lookup table of a WIM file.
 496  */
 497 WIMLIBAPI void wimlib_print_lookup_table(WIMStruct *w)
 498 {
 499         for_lookup_table_entry(w->lookup_table,
 500                                do_print_lookup_table_entry,
 501                                NULL);
 502 }
 503
 504 /*
 505  * Looks up an entry in the lookup table.
 506  */
 507 struct lookup_table_entry *
 508 __lookup_resource(const struct lookup_table *table, const u8 hash[])
 509 {
 510         size_t i;
 511         struct lookup_table_entry *lte;
 512         struct hlist_node *pos;
 513
 514         wimlib_assert(table != NULL);
 515         wimlib_assert(hash != NULL);
 516
 517         i = *(size_t*)hash % table->capacity;
 518         hlist_for_each_entry(lte, pos, &table->array[i], hash_list)
 519                 if (hashes_equal(hash, lte->hash))
 520                         return lte;
 521         return NULL;
 522 }
 523
 524 #ifdef WITH_FUSE
 525 /*
 526  * Finds the dentry, lookup table entry, and stream index for a WIM file stream,
 527  * given a path name.
 528  *
 529  * This is only for pre-resolved inodes.
 530  */
 531 int lookup_resource(WIMStruct *w, const char *path,
 532                     int lookup_flags,
 533                     struct dentry **dentry_ret,
 534                     struct lookup_table_entry **lte_ret,
 535                     u16 *stream_idx_ret)
 536 {
 537         struct dentry *dentry;
 538         struct lookup_table_entry *lte;
 539         u16 stream_idx;
 540         const char *stream_name = NULL;
 541         struct inode *inode;
 542         char *p = NULL;
 543
 544         if (lookup_flags & LOOKUP_FLAG_ADS_OK) {
 545                 stream_name = path_stream_name(path);
 546                 if (stream_name) {
 547                         p = (char*)stream_name - 1;
 548                         *p = '\0';
 549                 }
 550         }
 551
 552         dentry = get_dentry(w, path);
 553         if (p)
 554                 *p = ':';
 555         if (!dentry)
 556                 return -ENOENT;
 557
 558         inode = dentry->d_inode;
 559
 560         wimlib_assert(inode->resolved);
 561
 562         if (!(lookup_flags & LOOKUP_FLAG_DIRECTORY_OK)
 563               && inode_is_directory(inode))
 564                 return -EISDIR;
 565
 566         if (stream_name) {
 567                 struct ads_entry *ads_entry;
 568                 u16 ads_idx;
 569                 ads_entry = inode_get_ads_entry(inode, stream_name,
 570                                                 &ads_idx);
 571                 if (ads_entry) {
 572                         stream_idx = ads_idx + 1;
 573                         lte = ads_entry->lte;
 574                         goto out;
 575                 } else {
 576                         return -ENOENT;
 577                 }
 578         } else {
 579                 lte = inode->lte;
 580                 stream_idx = 0;
 581         }
 582 out:
 583         if (dentry_ret)
 584                 *dentry_ret = dentry;
 585         if (lte_ret)
 586                 *lte_ret = lte;
 587         if (stream_idx_ret)
 588                 *stream_idx_ret = stream_idx;
 589         return 0;
 590 }
 591 #endif
 592
 593 static void inode_resolve_ltes(struct inode *inode, struct lookup_table *table)
 594 {
 595         struct lookup_table_entry *lte;
 596
 597         wimlib_assert(!inode->resolved);
 598
 599         /* Resolve the default file stream */
 600         lte = __lookup_resource(table, inode->hash);
 601         inode->lte = lte;
 602         inode->resolved = true;
 603
 604         /* Resolve the alternate data streams */
 605         for (u16 i = 0; i < inode->num_ads; i++) {
 606                 struct ads_entry *cur_entry = &inode->ads_entries[i];
 607                 lte = __lookup_resource(table, cur_entry->hash);
 608                 cur_entry->lte = lte;
 609         }
 610 }
 611
 612 static void inode_unresolve_ltes(struct inode *inode)
 613 {
 614         wimlib_assert(inode->resolved);
 615         if (inode->lte)
 616                 copy_hash(inode->hash, inode->lte->hash);
 617         else
 618                 zero_out_hash(inode->hash);
 619
 620         for (u16 i = 0; i < inode->num_ads; i++) {
 621                 if (inode->ads_entries[i].lte)
 622                         copy_hash(inode->ads_entries[i].hash,
 623                                   inode->ads_entries[i].lte->hash);
 624                 else
 625                         zero_out_hash(inode->ads_entries[i].hash);
 626         }
 627         inode->resolved = false;
 628 }
 629
 630 /* Resolve a dentry's lookup table entries
 631  *
 632  * This replaces the SHA1 hash fields (which are used to lookup an entry in the
 633  * lookup table) with pointers directly to the lookup table entries.  A circular
 634  * linked list of streams sharing the same lookup table entry is created.
 635  *
 636  * This function always succeeds; unresolved lookup table entries are given a
 637  * NULL pointer.
 638  */
 639 int dentry_resolve_ltes(struct dentry *dentry, void *table)
 640 {
 641         if (!dentry->d_inode->resolved)
 642                 inode_resolve_ltes(dentry->d_inode, table);
 643         return 0;
 644 }
 645
 646 int dentry_unresolve_ltes(struct dentry *dentry, void *ignore)
 647 {
 648         if (dentry->d_inode->resolved)
 649                 inode_unresolve_ltes(dentry->d_inode);
 650         return 0;
 651 }
 652
 653 /* Return the lookup table entry for the unnamed data stream of an inode, or
 654  * NULL if there is none.
 655  *
 656  * You'd think this would be easier than it actually is, since the unnamed data
 657  * stream should be the one referenced from the inode itself.  Alas, if there
 658  * are named data streams, Microsoft's "imagex.exe" program will put the unnamed
 659  * data stream in one of the alternate data streams instead of inside the WIM
 660  * dentry itself.  So we need to check the alternate data streams too.
 661  *
 662  * Also, note that a dentry may appear to have more than one unnamed stream, but
 663  * if the SHA1 message digest is all 0's then the corresponding stream does not
 664  * really "count" (this is the case for the inode's own file stream when the
 665  * file stream that should be there is actually in one of the alternate stream
 666  * entries.).  This is despite the fact that we may need to extract such a
 667  * missing entry as an empty file or empty named data stream.
 668  */
 669 struct lookup_table_entry *
 670 inode_unnamed_lte(const struct inode *inode,
 671                    const struct lookup_table *table)
 672 {
 673         if (inode->resolved)
 674                 return inode_unnamed_lte_resolved(inode);
 675         else
 676                 return inode_unnamed_lte_unresolved(inode, table);
 677 }
 678