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