wimlib.net Git - wimlib/blob - src/lookup_table.c

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