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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 lookup_table_entry **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
  74 void free_lookup_table_entry(struct lookup_table_entry *lte)
  75 {
  76         if (lte) {
  77                 if (lte->staging_list.next)
  78                         list_del(&lte->staging_list);
  79                 FREE(lte->file_on_disk);
  80                 FREE(lte);
  81         }
  82 }
  83
  84 /*
  85  * Inserts an entry into the lookup table.
  86  *
  87  * @lookup_table:       A pointer to the lookup table.
  88  * @entry:              A pointer to the entry to insert.
  89  */
  90 void lookup_table_insert(struct lookup_table *table,
  91                          struct lookup_table_entry *lte)
  92 {
  93         size_t pos;
  94         pos = lte->hash_short % table->capacity;
  95         lte->next = table->array[pos];
  96         table->array[pos] = lte;
  97         /* XXX Make the table grow when too many entries have been inserted. */
  98         table->num_entries++;
  99 }
 100
 101
 102 /* Unlinks a lookup table entry from the table; does not free it. */
 103 void lookup_table_unlink(struct lookup_table *table,
 104                          struct lookup_table_entry *lte)
 105 {
 106         size_t pos;
 107         struct lookup_table_entry *prev, *cur_entry, *next;
 108
 109         pos = lte->hash_short % table->capacity;
 110         prev = NULL;
 111         cur_entry = table->array[pos];
 112
 113         while (cur_entry) {
 114                 next = cur_entry->next;
 115                 if (cur_entry == lte) {
 116                         if (prev)
 117                                 prev->next = next;
 118                         else
 119                                 table->array[pos] = next;
 120                         table->num_entries--;
 121                         return;
 122                 }
 123                 prev = cur_entry;
 124                 cur_entry = next;
 125         }
 126 }
 127
 128
 129 /* Decrement the reference count for the dentry having hash value @hash in the
 130  * lookup table.  The lookup table entry is unlinked and freed if there are no
 131  * references to in remaining.  */
 132 struct lookup_table_entry *
 133 lookup_table_decrement_refcnt(struct lookup_table* table, const u8 hash[])
 134 {
 135         size_t pos = *(size_t*)hash % table->capacity;
 136         struct lookup_table_entry *prev = NULL;
 137         struct lookup_table_entry *entry = table->array[pos];
 138         struct lookup_table_entry *next;
 139         while (entry) {
 140                 next = entry->next;
 141                 if (memcmp(hash, entry->hash, WIM_HASH_SIZE) == 0) {
 142                         wimlib_assert(entry->refcnt != 0);
 143                         if (--entry->refcnt == 0) {
 144                                 if (entry->num_opened_fds == 0) {
 145                                         free_lookup_table_entry(entry);
 146                                         entry = NULL;
 147                                 }
 148                                 if (prev)
 149                                         prev->next = next;
 150                                 else
 151                                         table->array[pos] = next;
 152                                 break;
 153                         }
 154                 }
 155                 prev = entry;
 156                 entry = next;
 157         }
 158         return entry;
 159 }
 160
 161 /* Like lookup_table_decrement_refcnt(), but for when we already know the lookup
 162  * table entry. */
 163 struct lookup_table_entry *
 164 lte_decrement_refcnt(struct lookup_table_entry *lte, struct lookup_table *table)
 165 {
 166         if (lte) {
 167                 wimlib_assert(lte->refcnt);
 168                 if (--lte->refcnt == 0) {
 169                         lookup_table_unlink(table, lte);
 170                         if (lte->num_opened_fds == 0) {
 171                                 free_lookup_table_entry(lte);
 172                                 lte = NULL;
 173                         }
 174                 }
 175         }
 176         return lte;
 177 }
 178
 179 /*
 180  * Calls a function on all the entries in the lookup table.  Stop early and
 181  * return nonzero if any call to the function returns nonzero.
 182  */
 183 int for_lookup_table_entry(struct lookup_table *table,
 184                            int (*visitor)(struct lookup_table_entry *, void *),
 185                            void *arg)
 186 {
 187         struct lookup_table_entry *entry, *next;
 188         size_t i;
 189         int ret;
 190
 191         for (i = 0; i < table->capacity; i++) {
 192                 entry = table->array[i];
 193                 while (entry) {
 194                         next = entry->next;
 195                         ret = visitor(entry, arg);
 196                         if (ret != 0)
 197                                 return ret;
 198                         entry = next;
 199                 }
 200         }
 201         return 0;
 202 }
 203
 204
 205 /*
 206  * Reads the lookup table from a WIM file.
 207  *
 208  * @fp:                 The FILE* for the WIM file.
 209  * @offset:             The offset of the lookup table resource.
 210  * @size:               The size of the lookup table resource.
 211  * @lookup_table_ret:   A pointer to a struct lookup_table structure into which the
 212  *                              lookup table will be returned.
 213  * @return:             True on success, false on failure.
 214  */
 215 int read_lookup_table(FILE *fp, u64 offset, u64 size,
 216                       struct lookup_table **table_ret)
 217 {
 218         size_t num_entries;
 219         u8     buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 220         int    ret;
 221         struct lookup_table *table;
 222         const u8 *p;
 223         struct lookup_table_entry *cur_entry;
 224
 225         DEBUG("Reading lookup table: offset %"PRIu64", size %"PRIu64"",
 226               offset, size);
 227
 228         if (fseeko(fp, offset, SEEK_SET) != 0) {
 229                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
 230                                  "lookup table", offset);
 231                 return WIMLIB_ERR_READ;
 232         }
 233
 234         num_entries = size / WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE;
 235         table = new_lookup_table(num_entries * 2 + 1);
 236         if (!table)
 237                 return WIMLIB_ERR_NOMEM;
 238
 239         while (num_entries--) {
 240                 if (fread(buf, 1, sizeof(buf), fp) != sizeof(buf)) {
 241                         if (feof(fp)) {
 242                                 ERROR("Unexpected EOF in WIM lookup table!");
 243                         } else {
 244                                 ERROR_WITH_ERRNO("Error reading WIM lookup "
 245                                                  "table");
 246                         }
 247                         ret = WIMLIB_ERR_READ;
 248                         goto out;
 249                 }
 250                 cur_entry = new_lookup_table_entry();
 251                 if (!cur_entry) {
 252                         ret = WIMLIB_ERR_NOMEM;
 253                         goto out;
 254                 }
 255
 256                 p = get_resource_entry(buf, &cur_entry->resource_entry);
 257                 p = get_u16(p, &cur_entry->part_number);
 258                 p = get_u32(p, &cur_entry->refcnt);
 259                 p = get_bytes(p, WIM_HASH_SIZE, cur_entry->hash);
 260                 lookup_table_insert(table, cur_entry);
 261         }
 262         DEBUG("Done reading lookup table.");
 263         *table_ret = table;
 264         return 0;
 265 out:
 266         free_lookup_table(table);
 267         return ret;
 268 }
 269
 270
 271 /*
 272  * Writes a lookup table entry to the output file.
 273  */
 274 int write_lookup_table_entry(struct lookup_table_entry *lte, void *__out)
 275 {
 276         FILE *out;
 277         u8 buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 278         u8 *p;
 279
 280         out = __out;
 281
 282         /* do not write lookup table entries for empty files */
 283         if (lte->output_resource_entry.original_size == 0)
 284                 return 0;
 285
 286         /* Don't write entries that have not had file resources or metadata
 287          * resources written for them. */
 288         if (lte->out_refcnt == 0)
 289                 return 0;
 290
 291         if (lte->output_resource_entry.flags & WIM_RESHDR_FLAG_METADATA)
 292                 DEBUG("Writing metadata entry at %lu (orig size = %zu)",
 293                       ftello(out), lte->output_resource_entry.original_size);
 294
 295         p = put_resource_entry(buf, &lte->output_resource_entry);
 296         p = put_u16(p, lte->part_number);
 297         p = put_u32(p, lte->out_refcnt);
 298         p = put_bytes(p, WIM_HASH_SIZE, lte->hash);
 299         if (fwrite(buf, 1, sizeof(buf), out) != sizeof(buf)) {
 300                 ERROR_WITH_ERRNO("Failed to write lookup table entry");
 301                 return WIMLIB_ERR_WRITE;
 302         }
 303         return 0;
 304 }
 305
 306 static int do_free_lookup_table_entry(struct lookup_table_entry *entry,
 307                                       void *ignore)
 308 {
 309         free_lookup_table_entry(entry);
 310         return 0;
 311 }
 312
 313 void free_lookup_table(struct lookup_table *table)
 314 {
 315         if (!table)
 316                 return;
 317         if (table->array) {
 318                 for_lookup_table_entry(table, do_free_lookup_table_entry, NULL);
 319                 FREE(table->array);
 320         }
 321         FREE(table);
 322 }
 323
 324 int zero_out_refcnts(struct lookup_table_entry *entry, void *ignore)
 325 {
 326         entry->out_refcnt = 0;
 327         return 0;
 328 }
 329
 330 int print_lookup_table_entry(struct lookup_table_entry *entry, void *ignore)
 331 {
 332         printf("Offset            = %"PRIu64" bytes\n",
 333                entry->resource_entry.offset);
 334         printf("Size              = %"PRIu64" bytes\n",
 335                (u64)entry->resource_entry.size);
 336         printf("Original size     = %"PRIu64" bytes\n",
 337                entry->resource_entry.original_size);
 338         printf("Part Number       = %hu\n", entry->part_number);
 339         printf("Reference Count   = %u\n", entry->refcnt);
 340         printf("Hash              = ");
 341         print_hash(entry->hash);
 342         putchar('\n');
 343         printf("Flags             = ");
 344         u8 flags = entry->resource_entry.flags;
 345         if (flags & WIM_RESHDR_FLAG_COMPRESSED)
 346                 fputs("WIM_RESHDR_FLAG_COMPRESSED, ", stdout);
 347         if (flags & WIM_RESHDR_FLAG_FREE)
 348                 fputs("WIM_RESHDR_FLAG_FREE, ", stdout);
 349         if (flags & WIM_RESHDR_FLAG_METADATA)
 350                 fputs("WIM_RESHDR_FLAG_METADATA, ", stdout);
 351         if (flags & WIM_RESHDR_FLAG_SPANNED)
 352                 fputs("WIM_RESHDR_FLAG_SPANNED, ", stdout);
 353         putchar('\n');
 354         if (entry->file_on_disk)
 355                 printf("File on Disk      = `%s'\n", entry->file_on_disk);
 356         putchar('\n');
 357         return 0;
 358 }
 359
 360 /*
 361  * Prints the lookup table of a WIM file.
 362  */
 363 WIMLIBAPI void wimlib_print_lookup_table(WIMStruct *w)
 364 {
 365         for_lookup_table_entry(w->lookup_table,
 366                                print_lookup_table_entry, NULL);
 367 }
 368
 369 /*
 370  * Looks up an entry in the lookup table.
 371  */
 372 struct lookup_table_entry *
 373 __lookup_resource(const struct lookup_table *lookup_table, const u8 hash[])
 374 {
 375         size_t pos;
 376         struct lookup_table_entry *lte;
 377
 378         pos = *(size_t*)hash % lookup_table->capacity;
 379         lte = lookup_table->array[pos];
 380         while (lte) {
 381                 if (memcmp(hash, lte->hash, WIM_HASH_SIZE) == 0)
 382                         return lte;
 383                 lte = lte->next;
 384         }
 385         return NULL;
 386 }
 387
 388 /*
 389  * Finds the dentry, lookup table entry, and stream index for a WIM file stream,
 390  * given a path name.
 391  *
 392  * This is only for pre-resolved dentries.
 393  */
 394 int lookup_resource(WIMStruct *w, const char *path,
 395                     int lookup_flags,
 396                     struct dentry **dentry_ret,
 397                     struct lookup_table_entry **lte_ret,
 398                     unsigned *stream_idx_ret)
 399 {
 400         struct dentry *dentry;
 401         struct lookup_table_entry *lte;
 402         unsigned stream_idx;
 403         dentry = get_dentry(w, path);
 404         if (!dentry)
 405                 return -ENOENT;
 406
 407         wimlib_assert(dentry->resolved);
 408
 409         lte = dentry->lte;
 410         if (!(lookup_flags & LOOKUP_FLAG_DIRECTORY_OK)
 411               && dentry_is_directory(dentry))
 412                 return -EISDIR;
 413         stream_idx = 0;
 414         if (lookup_flags & LOOKUP_FLAG_ADS_OK) {
 415                 const char *stream_name = path_stream_name(path);
 416                 if (stream_name) {
 417                         size_t stream_name_len = strlen(stream_name);
 418                         for (u16 i = 0; i < dentry->num_ads; i++) {
 419                                 if (ads_entry_has_name(&dentry->ads_entries[i],
 420                                                        stream_name,
 421                                                        stream_name_len))
 422                                 {
 423                                         stream_idx = i + 1;
 424                                         lte = dentry->ads_entries[i].lte;
 425                                         goto out;
 426                                 }
 427                         }
 428                         return -ENOENT;
 429                 }
 430         }
 431 out:
 432         if (dentry_ret)
 433                 *dentry_ret = dentry;
 434         if (lte_ret)
 435                 *lte_ret = lte;
 436         if (stream_idx_ret)
 437                 *stream_idx_ret = stream_idx;
 438         return 0;
 439 }
 440
 441 /* Resolve a dentry's lookup table entries
 442  *
 443  * This replaces the SHA1 hash fields (which are used to lookup an entry in the
 444  * lookup table) with pointers directly to the lookup table entries.  A circular
 445  * linked list of streams sharing the same lookup table entry is created.
 446  *
 447  * This function always succeeds; unresolved lookup table entries are given a
 448  * NULL pointer.
 449  */
 450 int dentry_resolve_ltes(struct dentry *dentry, void *__table)
 451 {
 452         struct lookup_table *table = __table;
 453         struct lookup_table_entry *lte;
 454
 455         wimlib_assert(!dentry->resolved);
 456
 457         /* Resolve the default file stream */
 458         lte = __lookup_resource(table, dentry->hash);
 459         if (lte)
 460                 list_add(&dentry->lte_group_list.list, &lte->lte_group_list);
 461         else
 462                 INIT_LIST_HEAD(&dentry->lte_group_list.list);
 463         dentry->lte = lte;
 464         dentry->lte_group_list.type = STREAM_TYPE_NORMAL;
 465         dentry->resolved = true;
 466
 467         /* Resolve the alternate data streams */
 468         if (dentry->ads_entries_status != ADS_ENTRIES_USER) {
 469                 for (u16 i = 0; i < dentry->num_ads; i++) {
 470                         struct ads_entry *cur_entry = &dentry->ads_entries[i];
 471
 472                         lte = __lookup_resource(table, cur_entry->hash);
 473                         if (lte)
 474                                 list_add(&cur_entry->lte_group_list.list,
 475                                          &lte->lte_group_list);
 476                         else
 477                                 INIT_LIST_HEAD(&cur_entry->lte_group_list.list);
 478                         cur_entry->lte = lte;
 479                         cur_entry->lte_group_list.type = STREAM_TYPE_ADS;
 480                 }
 481         }
 482         return 0;
 483 }