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