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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         return lte;
  70 }
  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 /*
  84  * Inserts an entry into the lookup table.
  85  *
  86  * @lookup_table:       A pointer to the lookup table.
  87  * @entry:              A pointer to the entry to insert.
  88  */
  89 void lookup_table_insert(struct lookup_table *table,
  90                          struct lookup_table_entry *lte)
  91 {
  92         size_t pos;
  93         pos = lte->hash_short % table->capacity;
  94         lte->next = table->array[pos];
  95         table->array[pos] = lte;
  96         /* XXX Make the table grow when too many entries have been inserted. */
  97         table->num_entries++;
  98 }
  99
 100
 101 /* Unlinks a lookup table entry from the table; does not free it. */
 102 void lookup_table_unlink(struct lookup_table *table,
 103                          struct lookup_table_entry *lte)
 104 {
 105         size_t pos;
 106         struct lookup_table_entry *prev, *cur_entry, *next;
 107
 108         pos = lte->hash_short % table->capacity;
 109         prev = NULL;
 110         cur_entry = table->array[pos];
 111
 112         while (cur_entry) {
 113                 next = cur_entry->next;
 114                 if (cur_entry == lte) {
 115                         if (prev)
 116                                 prev->next = next;
 117                         else
 118                                 table->array[pos] = next;
 119                         table->num_entries--;
 120                         return;
 121                 }
 122                 prev = cur_entry;
 123                 cur_entry = next;
 124         }
 125 }
 126
 127
 128 /* Decrement the reference count for the dentry having hash value @hash in the
 129  * lookup table.  The lookup table entry is unlinked and freed if there are no
 130  * references to in remaining.  */
 131 struct lookup_table_entry *
 132 lookup_table_decrement_refcnt(struct lookup_table* table, const u8 hash[])
 133 {
 134         size_t pos = *(size_t*)hash % table->capacity;
 135         struct lookup_table_entry *prev = NULL;
 136         struct lookup_table_entry *entry = table->array[pos];
 137         struct lookup_table_entry *next;
 138         while (entry) {
 139                 next = entry->next;
 140                 if (memcmp(hash, entry->hash, WIM_HASH_SIZE) == 0) {
 141                         wimlib_assert(entry->refcnt != 0);
 142                         if (--entry->refcnt == 0) {
 143                                 if (entry->num_opened_fds == 0) {
 144                                         free_lookup_table_entry(entry);
 145                                         entry = NULL;
 146                                 }
 147                                 if (prev)
 148                                         prev->next = next;
 149                                 else
 150                                         table->array[pos] = next;
 151                                 break;
 152                         }
 153                 }
 154                 prev = entry;
 155                 entry = next;
 156         }
 157         return entry;
 158 }
 159
 160
 161 /*
 162  * Calls a function on all the entries in the lookup table.  Stop early and
 163  * return nonzero if any call to the function returns nonzero.
 164  */
 165 int for_lookup_table_entry(struct lookup_table *table,
 166                            int (*visitor)(struct lookup_table_entry *, void *),
 167                            void *arg)
 168 {
 169         struct lookup_table_entry *entry, *next;
 170         size_t i;
 171         int ret;
 172
 173         for (i = 0; i < table->capacity; i++) {
 174                 entry = table->array[i];
 175                 while (entry) {
 176                         next = entry->next;
 177                         ret = visitor(entry, arg);
 178                         if (ret != 0)
 179                                 return ret;
 180                         entry = next;
 181                 }
 182         }
 183         return 0;
 184 }
 185
 186
 187 /*
 188  * Reads the lookup table from a WIM file.
 189  *
 190  * @fp:                 The FILE* for the WIM file.
 191  * @offset:             The offset of the lookup table resource.
 192  * @size:               The size of the lookup table resource.
 193  * @lookup_table_ret:   A pointer to a struct lookup_table structure into which the
 194  *                              lookup table will be returned.
 195  * @return:             True on success, false on failure.
 196  */
 197 int read_lookup_table(FILE *fp, u64 offset, u64 size,
 198                       struct lookup_table **table_ret)
 199 {
 200         size_t num_entries;
 201         u8     buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 202         int    ret;
 203         struct lookup_table *table;
 204         const u8 *p;
 205         struct lookup_table_entry *cur_entry;
 206
 207         DEBUG("Reading lookup table: offset %"PRIu64", size %"PRIu64"",
 208               offset, size);
 209
 210         if (fseeko(fp, offset, SEEK_SET) != 0) {
 211                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
 212                                  "lookup table", offset);
 213                 return WIMLIB_ERR_READ;
 214         }
 215
 216         num_entries = size / WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE;
 217         table = new_lookup_table(num_entries * 2 + 1);
 218         if (!table)
 219                 return WIMLIB_ERR_NOMEM;
 220
 221         while (num_entries--) {
 222                 if (fread(buf, 1, sizeof(buf), fp) != sizeof(buf)) {
 223                         if (feof(fp)) {
 224                                 ERROR("Unexpected EOF in WIM lookup table!");
 225                         } else {
 226                                 ERROR_WITH_ERRNO("Error reading WIM lookup "
 227                                                  "table");
 228                         }
 229                         ret = WIMLIB_ERR_READ;
 230                         goto out;
 231                 }
 232                 cur_entry = new_lookup_table_entry();
 233                 if (!cur_entry) {
 234                         ret = WIMLIB_ERR_NOMEM;
 235                         goto out;
 236                 }
 237
 238                 p = get_resource_entry(buf, &cur_entry->resource_entry);
 239                 p = get_u16(p, &cur_entry->part_number);
 240                 p = get_u32(p, &cur_entry->refcnt);
 241                 p = get_bytes(p, WIM_HASH_SIZE, cur_entry->hash);
 242                 lookup_table_insert(table, cur_entry);
 243         }
 244         DEBUG("Done reading lookup table.");
 245         *table_ret = table;
 246         return 0;
 247 out:
 248         free_lookup_table(table);
 249         return ret;
 250 }
 251
 252
 253 /*
 254  * Writes a lookup table entry to the output file.
 255  */
 256 int write_lookup_table_entry(struct lookup_table_entry *lte, void *__out)
 257 {
 258         FILE *out;
 259         u8 buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 260         u8 *p;
 261
 262         out = __out;
 263
 264         /* do not write lookup table entries for empty files */
 265         if (lte->output_resource_entry.original_size == 0)
 266                 return 0;
 267
 268         /* Don't write entries that have not had file resources or metadata
 269          * resources written for them. */
 270         if (lte->out_refcnt == 0)
 271                 return 0;
 272
 273         if (lte->output_resource_entry.flags & WIM_RESHDR_FLAG_METADATA)
 274                 DEBUG("Writing metadata entry at %lu (orig size = %zu)",
 275                       ftello(out), lte->output_resource_entry.original_size);
 276
 277         p = put_resource_entry(buf, &lte->output_resource_entry);
 278         p = put_u16(p, lte->part_number);
 279         p = put_u32(p, lte->out_refcnt);
 280         p = put_bytes(p, WIM_HASH_SIZE, lte->hash);
 281         if (fwrite(buf, 1, sizeof(buf), out) != sizeof(buf)) {
 282                 ERROR_WITH_ERRNO("Failed to write lookup table entry");
 283                 return WIMLIB_ERR_WRITE;
 284         }
 285         return 0;
 286 }
 287
 288 static int do_free_lookup_table_entry(struct lookup_table_entry *entry,
 289                                       void *ignore)
 290 {
 291         free_lookup_table_entry(entry);
 292         return 0;
 293 }
 294
 295 void free_lookup_table(struct lookup_table *table)
 296 {
 297         if (!table)
 298                 return;
 299         if (table->array) {
 300                 for_lookup_table_entry(table, do_free_lookup_table_entry, NULL);
 301                 FREE(table->array);
 302         }
 303         FREE(table);
 304 }
 305
 306 int zero_out_refcnts(struct lookup_table_entry *entry, void *ignore)
 307 {
 308         entry->out_refcnt = 0;
 309         return 0;
 310 }
 311
 312 int print_lookup_table_entry(struct lookup_table_entry *entry, void *ignore)
 313 {
 314         printf("Offset            = %"PRIu64" bytes\n",
 315                entry->resource_entry.offset);
 316         printf("Size              = %"PRIu64" bytes\n",
 317                (u64)entry->resource_entry.size);
 318         printf("Original size     = %"PRIu64" bytes\n",
 319                entry->resource_entry.original_size);
 320         printf("Part Number       = %hu\n", entry->part_number);
 321         printf("Reference Count   = %u\n", entry->refcnt);
 322         printf("Hash              = ");
 323         print_hash(entry->hash);
 324         putchar('\n');
 325         printf("Flags             = ");
 326         u8 flags = entry->resource_entry.flags;
 327         if (flags & WIM_RESHDR_FLAG_COMPRESSED)
 328                 fputs("WIM_RESHDR_FLAG_COMPRESSED, ", stdout);
 329         if (flags & WIM_RESHDR_FLAG_FREE)
 330                 fputs("WIM_RESHDR_FLAG_FREE, ", stdout);
 331         if (flags & WIM_RESHDR_FLAG_METADATA)
 332                 fputs("WIM_RESHDR_FLAG_METADATA, ", stdout);
 333         if (flags & WIM_RESHDR_FLAG_SPANNED)
 334                 fputs("WIM_RESHDR_FLAG_SPANNED, ", stdout);
 335         putchar('\n');
 336         if (entry->file_on_disk)
 337                 printf("File on Disk      = `%s'\n", entry->file_on_disk);
 338         putchar('\n');
 339         return 0;
 340 }
 341
 342 /*
 343  * Prints the lookup table of a WIM file.
 344  */
 345 WIMLIBAPI void wimlib_print_lookup_table(WIMStruct *w)
 346 {
 347         for_lookup_table_entry(w->lookup_table,
 348                                print_lookup_table_entry, NULL);
 349 }
 350
 351 /*
 352  * Looks up an entry in the lookup table.
 353  */
 354 struct lookup_table_entry *
 355 __lookup_resource(const struct lookup_table *lookup_table, const u8 hash[])
 356 {
 357         size_t pos;
 358         struct lookup_table_entry *lte;
 359
 360         pos = *(size_t*)hash % lookup_table->capacity;
 361         lte = lookup_table->array[pos];
 362         while (lte) {
 363                 if (memcmp(hash, lte->hash, WIM_HASH_SIZE) == 0)
 364                         return lte;
 365                 lte = lte->next;
 366         }
 367         return NULL;
 368 }
 369
 370 int lookup_resource(WIMStruct *w, const char *path,
 371                     int lookup_flags,
 372                     struct dentry **dentry_ret,
 373                     struct lookup_table_entry **lte_ret,
 374                     unsigned *stream_idx_ret)
 375 {
 376         struct dentry *dentry = get_dentry(w, path);
 377         struct lookup_table_entry *lte;
 378         unsigned stream_idx = 0;
 379         const u8 *hash = dentry->hash;
 380         if (!dentry)
 381                 return -ENOENT;
 382         if (!(lookup_flags & LOOKUP_FLAG_DIRECTORY_OK)
 383               && dentry_is_directory(dentry))
 384                 return -EISDIR;
 385         if (lookup_flags & LOOKUP_FLAG_ADS_OK) {
 386                 const char *stream_name = path_stream_name(path);
 387                 if (stream_name) {
 388                         size_t stream_name_len = strlen(stream_name);
 389                         for (u16 i = 0; i < dentry->num_ads; i++) {
 390                                 if (ads_entry_has_name(&dentry->ads_entries[i],
 391                                                        stream_name,
 392                                                        stream_name_len))
 393                                 {
 394                                         stream_idx = i + 1;
 395                                         hash = dentry->ads_entries[i].hash;
 396                                         goto do_lookup;
 397                                 }
 398                         }
 399                         return -ENOENT;
 400                 }
 401         }
 402 do_lookup:
 403         lte = __lookup_resource(w->lookup_table, hash);
 404         if (dentry_ret)
 405                 *dentry_ret = dentry;
 406         if (lte_ret)
 407                 *lte_ret = lte;
 408         if (stream_idx_ret)
 409                 *stream_idx_ret = stream_idx;
 410         return 0;
 411 }