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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
  31 struct lookup_table *new_lookup_table(size_t capacity)
  32 {
  33         struct lookup_table *table;
  34         struct lookup_table_entry **array;
  35
  36         table = MALLOC(sizeof(struct lookup_table));
  37         if (!table)
  38                 goto err;
  39         array = CALLOC(capacity, sizeof(array[0]));
  40         if (!array) {
  41                 FREE(table);
  42                 goto err;
  43         }
  44         table->num_entries = 0;
  45         table->capacity = capacity;
  46         table->array = array;
  47         return table;
  48 err:
  49         ERROR("Failed to allocate memory for lookup table with capacity %zu",
  50               capacity);
  51         return NULL;
  52 }
  53
  54 struct lookup_table_entry *new_lookup_table_entry()
  55 {
  56         struct lookup_table_entry *lte;
  57
  58         lte = CALLOC(1, sizeof(struct lookup_table_entry));
  59         if (!lte) {
  60                 ERROR("Out of memory (tried to allocate %zu bytes for "
  61                       "lookup table entry)",
  62                       sizeof(struct lookup_table_entry));
  63                 return NULL;
  64         }
  65
  66         lte->part_number  = 1;
  67         lte->refcnt       = 1;
  68         return lte;
  69 }
  70
  71
  72
  73 /*
  74  * Inserts an entry into the lookup table.
  75  *
  76  * @lookup_table:       A pointer to the lookup table.
  77  * @entry:              A pointer to the entry to insert.
  78  */
  79 void lookup_table_insert(struct lookup_table *table,
  80                          struct lookup_table_entry *lte)
  81 {
  82         size_t pos;
  83         pos = lte->hash_short % table->capacity;
  84         lte->next = table->array[pos];
  85         table->array[pos] = lte;
  86         /* XXX Make the table grow when too many entries have been inserted. */
  87         table->num_entries++;
  88 }
  89
  90
  91 /* Unlinks a lookup table entry from the table; does not free it. */
  92 void lookup_table_unlink(struct lookup_table *table,
  93                          struct lookup_table_entry *lte)
  94 {
  95         size_t pos;
  96         struct lookup_table_entry *prev, *cur_entry, *next;
  97
  98         pos = lte->hash_short % table->capacity;
  99         prev = NULL;
 100         cur_entry = table->array[pos];
 101
 102         while (cur_entry) {
 103                 next = cur_entry->next;
 104                 if (cur_entry == lte) {
 105                         if (prev)
 106                                 prev->next = next;
 107                         else
 108                                 table->array[pos] = next;
 109                         table->num_entries--;
 110                         return;
 111                 }
 112                 prev = cur_entry;
 113                 cur_entry = next;
 114         }
 115 }
 116
 117
 118 /* Decrement the reference count for the dentry having hash value @hash in the
 119  * lookup table.  The lookup table entry is unlinked and freed if there are no
 120  * references to in remaining.  */
 121 struct lookup_table_entry *
 122 lookup_table_decrement_refcnt(struct lookup_table* table, const u8 hash[])
 123 {
 124         size_t pos = *(size_t*)hash % table->capacity;
 125         struct lookup_table_entry *prev = NULL;
 126         struct lookup_table_entry *entry = table->array[pos];
 127         struct lookup_table_entry *next;
 128         while (entry) {
 129                 next = entry->next;
 130                 if (memcmp(hash, entry->hash, WIM_HASH_SIZE) == 0) {
 131                         wimlib_assert(entry->refcnt != 0);
 132                         if (--entry->refcnt == 0) {
 133                                 if (entry->num_opened_fds == 0) {
 134                                         free_lookup_table_entry(entry);
 135                                         entry = NULL;
 136                                 }
 137                                 if (prev)
 138                                         prev->next = next;
 139                                 else
 140                                         table->array[pos] = next;
 141                                 break;
 142                         }
 143                 }
 144                 prev = entry;
 145                 entry = next;
 146         }
 147         return entry;
 148 }
 149
 150
 151 /*
 152  * Calls a function on all the entries in the lookup table.  Stop early and
 153  * return nonzero if any call to the function returns nonzero.
 154  */
 155 int for_lookup_table_entry(struct lookup_table *table,
 156                            int (*visitor)(struct lookup_table_entry *, void *),
 157                            void *arg)
 158 {
 159         struct lookup_table_entry *entry, *next;
 160         size_t i;
 161         int ret;
 162
 163         for (i = 0; i < table->capacity; i++) {
 164                 entry = table->array[i];
 165                 while (entry) {
 166                         next = entry->next;
 167                         ret = visitor(entry, arg);
 168                         if (ret != 0)
 169                                 return ret;
 170                         entry = next;
 171                 }
 172         }
 173         return 0;
 174 }
 175
 176
 177 /*
 178  * Reads the lookup table from a WIM file.
 179  *
 180  * @fp:                 The FILE* for the WIM file.
 181  * @offset:             The offset of the lookup table resource.
 182  * @size:               The size of the lookup table resource.
 183  * @lookup_table_ret:   A pointer to a struct lookup_table structure into which the
 184  *                              lookup table will be returned.
 185  * @return:             True on success, false on failure.
 186  */
 187 int read_lookup_table(FILE *fp, u64 offset, u64 size,
 188                       struct lookup_table **table_ret)
 189 {
 190         size_t num_entries;
 191         u8     buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 192         int    ret;
 193         struct lookup_table *table;
 194         const u8 *p;
 195         struct lookup_table_entry *cur_entry;
 196
 197         DEBUG("Reading lookup table: offset %"PRIu64", size %"PRIu64"",
 198               offset, size);
 199
 200         if (fseeko(fp, offset, SEEK_SET) != 0) {
 201                 ERROR_WITH_ERRNO("Failed to seek to byte %"PRIu64" to read "
 202                                  "lookup table", offset);
 203                 return WIMLIB_ERR_READ;
 204         }
 205
 206         num_entries = size / WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE;
 207         table = new_lookup_table(num_entries * 2 + 1);
 208         if (!table)
 209                 return WIMLIB_ERR_NOMEM;
 210
 211         while (num_entries--) {
 212                 if (fread(buf, 1, sizeof(buf), fp) != sizeof(buf)) {
 213                         if (feof(fp)) {
 214                                 ERROR("Unexpected EOF in WIM lookup table!");
 215                         } else {
 216                                 ERROR_WITH_ERRNO("Error reading WIM lookup "
 217                                                  "table");
 218                         }
 219                         ret = WIMLIB_ERR_READ;
 220                         goto out;
 221                 }
 222                 cur_entry = new_lookup_table_entry();
 223                 if (!cur_entry) {
 224                         ret = WIMLIB_ERR_NOMEM;
 225                         goto out;
 226                 }
 227
 228                 p = get_resource_entry(buf, &cur_entry->resource_entry);
 229                 p = get_u16(p, &cur_entry->part_number);
 230                 p = get_u32(p, &cur_entry->refcnt);
 231                 p = get_bytes(p, WIM_HASH_SIZE, cur_entry->hash);
 232                 lookup_table_insert(table, cur_entry);
 233         }
 234         DEBUG("Done reading lookup table.");
 235         *table_ret = table;
 236         return 0;
 237 out:
 238         free_lookup_table(table);
 239         return ret;
 240 }
 241
 242
 243 /*
 244  * Writes a lookup table entry to the output file.
 245  */
 246 int write_lookup_table_entry(struct lookup_table_entry *lte, void *__out)
 247 {
 248         FILE *out;
 249         u8 buf[WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE];
 250         u8 *p;
 251
 252         out = __out;
 253
 254         /* do not write lookup table entries for empty files */
 255         if (lte->output_resource_entry.original_size == 0)
 256                 return 0;
 257
 258         /* Don't write entries that have not had file resources or metadata
 259          * resources written for them. */
 260         if (lte->out_refcnt == 0)
 261                 return 0;
 262
 263         if (lte->output_resource_entry.flags & WIM_RESHDR_FLAG_METADATA)
 264                 DEBUG("Writing metadata entry at %lu", ftello(out));
 265
 266         p = put_resource_entry(buf, &lte->output_resource_entry);
 267         p = put_u16(p, lte->part_number);
 268         p = put_u32(p, lte->out_refcnt);
 269         p = put_bytes(p, WIM_HASH_SIZE, lte->hash);
 270         if (fwrite(buf, 1, sizeof(buf), out) != sizeof(buf)) {
 271                 ERROR_WITH_ERRNO("Failed to write lookup table entry");
 272                 return WIMLIB_ERR_WRITE;
 273         }
 274         return 0;
 275 }
 276
 277 static int do_free_lookup_table_entry(struct lookup_table_entry *entry,
 278                                       void *ignore)
 279 {
 280         free_lookup_table_entry(entry);
 281         return 0;
 282 }
 283
 284 void free_lookup_table(struct lookup_table *table)
 285 {
 286         if (!table)
 287                 return;
 288         if (table->array) {
 289                 for_lookup_table_entry(table, do_free_lookup_table_entry, NULL);
 290                 FREE(table->array);
 291         }
 292         FREE(table);
 293 }
 294
 295 int zero_out_refcnts(struct lookup_table_entry *entry, void *ignore)
 296 {
 297         entry->out_refcnt = 0;
 298         return 0;
 299 }
 300
 301 int print_lookup_table_entry(struct lookup_table_entry *entry, void *ignore)
 302 {
 303         printf("Offset            = %"PRIu64" bytes\n",
 304                entry->resource_entry.offset);
 305         printf("Size              = %"PRIu64" bytes\n",
 306                (u64)entry->resource_entry.size);
 307         printf("Original size     = %"PRIu64" bytes\n",
 308                entry->resource_entry.original_size);
 309         printf("Part Number       = %hu\n", entry->part_number);
 310         printf("Reference Count   = %u\n", entry->refcnt);
 311         printf("Hash              = ");
 312         print_hash(entry->hash);
 313         putchar('\n');
 314         printf("Flags             = ");
 315         u8 flags = entry->resource_entry.flags;
 316         if (flags & WIM_RESHDR_FLAG_COMPRESSED)
 317                 fputs("WIM_RESHDR_FLAG_COMPRESSED, ", stdout);
 318         if (flags & WIM_RESHDR_FLAG_FREE)
 319                 fputs("WIM_RESHDR_FLAG_FREE, ", stdout);
 320         if (flags & WIM_RESHDR_FLAG_METADATA)
 321                 fputs("WIM_RESHDR_FLAG_METADATA, ", stdout);
 322         if (flags & WIM_RESHDR_FLAG_SPANNED)
 323                 fputs("WIM_RESHDR_FLAG_SPANNED, ", stdout);
 324         putchar('\n');
 325         if (entry->file_on_disk)
 326                 printf("File on Disk      = `%s'\n", entry->file_on_disk);
 327         putchar('\n');
 328         return 0;
 329 }
 330
 331 /*
 332  * Prints the lookup table of a WIM file.
 333  */
 334 WIMLIBAPI void wimlib_print_lookup_table(WIMStruct *w)
 335 {
 336         for_lookup_table_entry(w->lookup_table,
 337                                print_lookup_table_entry, NULL);
 338 }
 339
 340 /*
 341  * Looks up an entry in the lookup table.
 342  */
 343 struct lookup_table_entry *
 344 __lookup_resource(const struct lookup_table *lookup_table, const u8 hash[])
 345 {
 346         size_t pos;
 347         struct lookup_table_entry *lte;
 348
 349         pos = *(size_t*)hash % lookup_table->capacity;
 350         lte = lookup_table->array[pos];
 351         while (lte) {
 352                 if (memcmp(hash, lte->hash, WIM_HASH_SIZE) == 0)
 353                         return lte;
 354                 lte = lte->next;
 355         }
 356         return NULL;
 357 }
 358
 359 int lookup_resource(WIMStruct *w, const char *path,
 360                     int lookup_flags,
 361                     struct dentry **dentry_ret,
 362                     struct lookup_table_entry **lte_ret,
 363                     u8 **hash_ret)
 364 {
 365         struct dentry *dentry = get_dentry(w, path);
 366         struct lookup_table_entry *lte;
 367         u8 *hash;
 368         if (!dentry)
 369                 return -ENOENT;
 370         if (!(lookup_flags & LOOKUP_FLAG_DIRECTORY_OK)
 371               && dentry_is_directory(dentry))
 372                 return -EISDIR;
 373         if (lookup_flags & LOOKUP_FLAG_ADS_OK) {
 374                 const char *stream_name = path_stream_name(path);
 375                 if (stream_name) {
 376                         size_t stream_name_len = strlen(stream_name);
 377                         for (u16 i = 0; i < dentry->num_ads; i++) {
 378                                 if (ads_entry_has_name(&dentry->ads_entries[i],
 379                                                        stream_name,
 380                                                        stream_name_len))
 381                                 {
 382                                         hash = dentry->ads_entries[i].hash;
 383                                         goto do_lookup;
 384                                 }
 385                         }
 386                         return -ENOENT;
 387                 }
 388         }
 389         hash = dentry->hash;
 390 do_lookup:
 391         lte = __lookup_resource(w->lookup_table, hash);
 392         if (dentry_ret)
 393                 *dentry_ret = dentry;
 394         if (lte_ret)
 395                 *lte_ret = lte;
 396         if (hash_ret)
 397                 *hash_ret = hash;
 398         return 0;
 399 }