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