git.oblomov.eu Git - git/blob - midx.c

   1 #include "cache.h"
   2 #include "csum-file.h"
   3 #include "dir.h"
   4 #include "lockfile.h"
   5 #include "packfile.h"
   6 #include "object-store.h"
   7 #include "packfile.h"
   8 #include "midx.h"
   9
  10 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
  11 #define MIDX_VERSION 1
  12 #define MIDX_BYTE_FILE_VERSION 4
  13 #define MIDX_BYTE_HASH_VERSION 5
  14 #define MIDX_BYTE_NUM_CHUNKS 6
  15 #define MIDX_BYTE_NUM_PACKS 8
  16 #define MIDX_HASH_VERSION 1
  17 #define MIDX_HEADER_SIZE 12
  18 #define MIDX_HASH_LEN 20
  19 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
  20
  21 #define MIDX_MAX_CHUNKS 5
  22 #define MIDX_CHUNK_ALIGNMENT 4
  23 #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
  24 #define MIDX_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  25 #define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  26 #define MIDX_CHUNKID_OBJECTOFFSETS 0x4f4f4646 /* "OOFF" */
  27 #define MIDX_CHUNKID_LARGEOFFSETS 0x4c4f4646 /* "LOFF" */
  28 #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
  29 #define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
  30 #define MIDX_CHUNK_OFFSET_WIDTH (2 * sizeof(uint32_t))
  31 #define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
  32 #define MIDX_LARGE_OFFSET_NEEDED 0x80000000
  33
  34 static char *get_midx_filename(const char *object_dir)
  35 {
  36         return xstrfmt("%s/pack/multi-pack-index", object_dir);
  37 }
  38
  39 struct multi_pack_index *load_multi_pack_index(const char *object_dir)
  40 {
  41         struct multi_pack_index *m = NULL;
  42         int fd;
  43         struct stat st;
  44         size_t midx_size;
  45         void *midx_map = NULL;
  46         uint32_t hash_version;
  47         char *midx_name = get_midx_filename(object_dir);
  48         uint32_t i;
  49         const char *cur_pack_name;
  50
  51         fd = git_open(midx_name);
  52
  53         if (fd < 0)
  54                 goto cleanup_fail;
  55         if (fstat(fd, &st)) {
  56                 error_errno(_("failed to read %s"), midx_name);
  57                 goto cleanup_fail;
  58         }
  59
  60         midx_size = xsize_t(st.st_size);
  61
  62         if (midx_size < MIDX_MIN_SIZE) {
  63                 error(_("multi-pack-index file %s is too small"), midx_name);
  64                 goto cleanup_fail;
  65         }
  66
  67         FREE_AND_NULL(midx_name);
  68
  69         midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
  70
  71         FLEX_ALLOC_MEM(m, object_dir, object_dir, strlen(object_dir));
  72         m->fd = fd;
  73         m->data = midx_map;
  74         m->data_len = midx_size;
  75
  76         m->signature = get_be32(m->data);
  77         if (m->signature != MIDX_SIGNATURE) {
  78                 error(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
  79                       m->signature, MIDX_SIGNATURE);
  80                 goto cleanup_fail;
  81         }
  82
  83         m->version = m->data[MIDX_BYTE_FILE_VERSION];
  84         if (m->version != MIDX_VERSION) {
  85                 error(_("multi-pack-index version %d not recognized"),
  86                       m->version);
  87                 goto cleanup_fail;
  88         }
  89
  90         hash_version = m->data[MIDX_BYTE_HASH_VERSION];
  91         if (hash_version != MIDX_HASH_VERSION) {
  92                 error(_("hash version %u does not match"), hash_version);
  93                 goto cleanup_fail;
  94         }
  95         m->hash_len = MIDX_HASH_LEN;
  96
  97         m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
  98
  99         m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
 100
 101         for (i = 0; i < m->num_chunks; i++) {
 102                 uint32_t chunk_id = get_be32(m->data + MIDX_HEADER_SIZE +
 103                                              MIDX_CHUNKLOOKUP_WIDTH * i);
 104                 uint64_t chunk_offset = get_be64(m->data + MIDX_HEADER_SIZE + 4 +
 105                                                  MIDX_CHUNKLOOKUP_WIDTH * i);
 106
 107                 switch (chunk_id) {
 108                         case MIDX_CHUNKID_PACKNAMES:
 109                                 m->chunk_pack_names = m->data + chunk_offset;
 110                                 break;
 111
 112                         case MIDX_CHUNKID_OIDFANOUT:
 113                                 m->chunk_oid_fanout = (uint32_t *)(m->data + chunk_offset);
 114                                 break;
 115
 116                         case MIDX_CHUNKID_OIDLOOKUP:
 117                                 m->chunk_oid_lookup = m->data + chunk_offset;
 118                                 break;
 119
 120                         case MIDX_CHUNKID_OBJECTOFFSETS:
 121                                 m->chunk_object_offsets = m->data + chunk_offset;
 122                                 break;
 123
 124                         case MIDX_CHUNKID_LARGEOFFSETS:
 125                                 m->chunk_large_offsets = m->data + chunk_offset;
 126                                 break;
 127
 128                         case 0:
 129                                 die(_("terminating multi-pack-index chunk id appears earlier than expected"));
 130                                 break;
 131
 132                         default:
 133                                 /*
 134                                  * Do nothing on unrecognized chunks, allowing future
 135                                  * extensions to add optional chunks.
 136                                  */
 137                                 break;
 138                 }
 139         }
 140
 141         if (!m->chunk_pack_names)
 142                 die(_("multi-pack-index missing required pack-name chunk"));
 143         if (!m->chunk_oid_fanout)
 144                 die(_("multi-pack-index missing required OID fanout chunk"));
 145         if (!m->chunk_oid_lookup)
 146                 die(_("multi-pack-index missing required OID lookup chunk"));
 147         if (!m->chunk_object_offsets)
 148                 die(_("multi-pack-index missing required object offsets chunk"));
 149
 150         m->num_objects = ntohl(m->chunk_oid_fanout[255]);
 151
 152         m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
 153
 154         cur_pack_name = (const char *)m->chunk_pack_names;
 155         for (i = 0; i < m->num_packs; i++) {
 156                 m->pack_names[i] = cur_pack_name;
 157
 158                 cur_pack_name += strlen(cur_pack_name) + 1;
 159
 160                 if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0) {
 161                         error(_("multi-pack-index pack names out of order: '%s' before '%s'"),
 162                               m->pack_names[i - 1],
 163                               m->pack_names[i]);
 164                         goto cleanup_fail;
 165                 }
 166         }
 167
 168         return m;
 169
 170 cleanup_fail:
 171         free(m);
 172         free(midx_name);
 173         if (midx_map)
 174                 munmap(midx_map, midx_size);
 175         if (0 <= fd)
 176                 close(fd);
 177         return NULL;
 178 }
 179
 180 static size_t write_midx_header(struct hashfile *f,
 181                                 unsigned char num_chunks,
 182                                 uint32_t num_packs)
 183 {
 184         unsigned char byte_values[4];
 185
 186         hashwrite_be32(f, MIDX_SIGNATURE);
 187         byte_values[0] = MIDX_VERSION;
 188         byte_values[1] = MIDX_HASH_VERSION;
 189         byte_values[2] = num_chunks;
 190         byte_values[3] = 0; /* unused */
 191         hashwrite(f, byte_values, sizeof(byte_values));
 192         hashwrite_be32(f, num_packs);
 193
 194         return MIDX_HEADER_SIZE;
 195 }
 196
 197 struct pack_list {
 198         struct packed_git **list;
 199         char **names;
 200         uint32_t nr;
 201         uint32_t alloc_list;
 202         uint32_t alloc_names;
 203         size_t pack_name_concat_len;
 204 };
 205
 206 static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 207                              const char *file_name, void *data)
 208 {
 209         struct pack_list *packs = (struct pack_list *)data;
 210
 211         if (ends_with(file_name, ".idx")) {
 212                 ALLOC_GROW(packs->list, packs->nr + 1, packs->alloc_list);
 213                 ALLOC_GROW(packs->names, packs->nr + 1, packs->alloc_names);
 214
 215                 packs->list[packs->nr] = add_packed_git(full_path,
 216                                                         full_path_len,
 217                                                         0);
 218
 219                 if (!packs->list[packs->nr]) {
 220                         warning(_("failed to add packfile '%s'"),
 221                                 full_path);
 222                         return;
 223                 }
 224
 225                 if (open_pack_index(packs->list[packs->nr])) {
 226                         warning(_("failed to open pack-index '%s'"),
 227                                 full_path);
 228                         close_pack(packs->list[packs->nr]);
 229                         FREE_AND_NULL(packs->list[packs->nr]);
 230                         return;
 231                 }
 232
 233                 packs->names[packs->nr] = xstrdup(file_name);
 234                 packs->pack_name_concat_len += strlen(file_name) + 1;
 235                 packs->nr++;
 236         }
 237 }
 238
 239 struct pack_pair {
 240         uint32_t pack_int_id;
 241         char *pack_name;
 242 };
 243
 244 static int pack_pair_compare(const void *_a, const void *_b)
 245 {
 246         struct pack_pair *a = (struct pack_pair *)_a;
 247         struct pack_pair *b = (struct pack_pair *)_b;
 248         return strcmp(a->pack_name, b->pack_name);
 249 }
 250
 251 static void sort_packs_by_name(char **pack_names, uint32_t nr_packs, uint32_t *perm)
 252 {
 253         uint32_t i;
 254         struct pack_pair *pairs;
 255
 256         ALLOC_ARRAY(pairs, nr_packs);
 257
 258         for (i = 0; i < nr_packs; i++) {
 259                 pairs[i].pack_int_id = i;
 260                 pairs[i].pack_name = pack_names[i];
 261         }
 262
 263         QSORT(pairs, nr_packs, pack_pair_compare);
 264
 265         for (i = 0; i < nr_packs; i++) {
 266                 pack_names[i] = pairs[i].pack_name;
 267                 perm[pairs[i].pack_int_id] = i;
 268         }
 269
 270         free(pairs);
 271 }
 272
 273 struct pack_midx_entry {
 274         struct object_id oid;
 275         uint32_t pack_int_id;
 276         time_t pack_mtime;
 277         uint64_t offset;
 278 };
 279
 280 static int midx_oid_compare(const void *_a, const void *_b)
 281 {
 282         const struct pack_midx_entry *a = (const struct pack_midx_entry *)_a;
 283         const struct pack_midx_entry *b = (const struct pack_midx_entry *)_b;
 284         int cmp = oidcmp(&a->oid, &b->oid);
 285
 286         if (cmp)
 287                 return cmp;
 288
 289         if (a->pack_mtime > b->pack_mtime)
 290                 return -1;
 291         else if (a->pack_mtime < b->pack_mtime)
 292                 return 1;
 293
 294         return a->pack_int_id - b->pack_int_id;
 295 }
 296
 297 static void fill_pack_entry(uint32_t pack_int_id,
 298                             struct packed_git *p,
 299                             uint32_t cur_object,
 300                             struct pack_midx_entry *entry)
 301 {
 302         if (!nth_packed_object_oid(&entry->oid, p, cur_object))
 303                 die(_("failed to locate object %d in packfile"), cur_object);
 304
 305         entry->pack_int_id = pack_int_id;
 306         entry->pack_mtime = p->mtime;
 307
 308         entry->offset = nth_packed_object_offset(p, cur_object);
 309 }
 310
 311 /*
 312  * It is possible to artificially get into a state where there are many
 313  * duplicate copies of objects. That can create high memory pressure if
 314  * we are to create a list of all objects before de-duplication. To reduce
 315  * this memory pressure without a significant performance drop, automatically
 316  * group objects by the first byte of their object id. Use the IDX fanout
 317  * tables to group the data, copy to a local array, then sort.
 318  *
 319  * Copy only the de-duplicated entries (selected by most-recent modified time
 320  * of a packfile containing the object).
 321  */
 322 static struct pack_midx_entry *get_sorted_entries(struct packed_git **p,
 323                                                   uint32_t *perm,
 324                                                   uint32_t nr_packs,
 325                                                   uint32_t *nr_objects)
 326 {
 327         uint32_t cur_fanout, cur_pack, cur_object;
 328         uint32_t alloc_fanout, alloc_objects, total_objects = 0;
 329         struct pack_midx_entry *entries_by_fanout = NULL;
 330         struct pack_midx_entry *deduplicated_entries = NULL;
 331
 332         for (cur_pack = 0; cur_pack < nr_packs; cur_pack++)
 333                 total_objects += p[cur_pack]->num_objects;
 334
 335         /*
 336          * As we de-duplicate by fanout value, we expect the fanout
 337          * slices to be evenly distributed, with some noise. Hence,
 338          * allocate slightly more than one 256th.
 339          */
 340         alloc_objects = alloc_fanout = total_objects > 3200 ? total_objects / 200 : 16;
 341
 342         ALLOC_ARRAY(entries_by_fanout, alloc_fanout);
 343         ALLOC_ARRAY(deduplicated_entries, alloc_objects);
 344         *nr_objects = 0;
 345
 346         for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
 347                 uint32_t nr_fanout = 0;
 348
 349                 for (cur_pack = 0; cur_pack < nr_packs; cur_pack++) {
 350                         uint32_t start = 0, end;
 351
 352                         if (cur_fanout)
 353                                 start = get_pack_fanout(p[cur_pack], cur_fanout - 1);
 354                         end = get_pack_fanout(p[cur_pack], cur_fanout);
 355
 356                         for (cur_object = start; cur_object < end; cur_object++) {
 357                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 358                                 fill_pack_entry(perm[cur_pack], p[cur_pack], cur_object, &entries_by_fanout[nr_fanout]);
 359                                 nr_fanout++;
 360                         }
 361                 }
 362
 363                 QSORT(entries_by_fanout, nr_fanout, midx_oid_compare);
 364
 365                 /*
 366                  * The batch is now sorted by OID and then mtime (descending).
 367                  * Take only the first duplicate.
 368                  */
 369                 for (cur_object = 0; cur_object < nr_fanout; cur_object++) {
 370                         if (cur_object && !oidcmp(&entries_by_fanout[cur_object - 1].oid,
 371                                                   &entries_by_fanout[cur_object].oid))
 372                                 continue;
 373
 374                         ALLOC_GROW(deduplicated_entries, *nr_objects + 1, alloc_objects);
 375                         memcpy(&deduplicated_entries[*nr_objects],
 376                                &entries_by_fanout[cur_object],
 377                                sizeof(struct pack_midx_entry));
 378                         (*nr_objects)++;
 379                 }
 380         }
 381
 382         free(entries_by_fanout);
 383         return deduplicated_entries;
 384 }
 385
 386 static size_t write_midx_pack_names(struct hashfile *f,
 387                                     char **pack_names,
 388                                     uint32_t num_packs)
 389 {
 390         uint32_t i;
 391         unsigned char padding[MIDX_CHUNK_ALIGNMENT];
 392         size_t written = 0;
 393
 394         for (i = 0; i < num_packs; i++) {
 395                 size_t writelen = strlen(pack_names[i]) + 1;
 396
 397                 if (i && strcmp(pack_names[i], pack_names[i - 1]) <= 0)
 398                         BUG("incorrect pack-file order: %s before %s",
 399                             pack_names[i - 1],
 400                             pack_names[i]);
 401
 402                 hashwrite(f, pack_names[i], writelen);
 403                 written += writelen;
 404         }
 405
 406         /* add padding to be aligned */
 407         i = MIDX_CHUNK_ALIGNMENT - (written % MIDX_CHUNK_ALIGNMENT);
 408         if (i < MIDX_CHUNK_ALIGNMENT) {
 409                 memset(padding, 0, sizeof(padding));
 410                 hashwrite(f, padding, i);
 411                 written += i;
 412         }
 413
 414         return written;
 415 }
 416
 417 static size_t write_midx_oid_fanout(struct hashfile *f,
 418                                     struct pack_midx_entry *objects,
 419                                     uint32_t nr_objects)
 420 {
 421         struct pack_midx_entry *list = objects;
 422         struct pack_midx_entry *last = objects + nr_objects;
 423         uint32_t count = 0;
 424         uint32_t i;
 425
 426         /*
 427         * Write the first-level table (the list is sorted,
 428         * but we use a 256-entry lookup to be able to avoid
 429         * having to do eight extra binary search iterations).
 430         */
 431         for (i = 0; i < 256; i++) {
 432                 struct pack_midx_entry *next = list;
 433
 434                 while (next < last && next->oid.hash[0] == i) {
 435                         count++;
 436                         next++;
 437                 }
 438
 439                 hashwrite_be32(f, count);
 440                 list = next;
 441         }
 442
 443         return MIDX_CHUNK_FANOUT_SIZE;
 444 }
 445
 446 static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
 447                                     struct pack_midx_entry *objects,
 448                                     uint32_t nr_objects)
 449 {
 450         struct pack_midx_entry *list = objects;
 451         uint32_t i;
 452         size_t written = 0;
 453
 454         for (i = 0; i < nr_objects; i++) {
 455                 struct pack_midx_entry *obj = list++;
 456
 457                 if (i < nr_objects - 1) {
 458                         struct pack_midx_entry *next = list;
 459                         if (oidcmp(&obj->oid, &next->oid) >= 0)
 460                                 BUG("OIDs not in order: %s >= %s",
 461                                     oid_to_hex(&obj->oid),
 462                                     oid_to_hex(&next->oid));
 463                 }
 464
 465                 hashwrite(f, obj->oid.hash, (int)hash_len);
 466                 written += hash_len;
 467         }
 468
 469         return written;
 470 }
 471
 472 static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
 473                                         struct pack_midx_entry *objects, uint32_t nr_objects)
 474 {
 475         struct pack_midx_entry *list = objects;
 476         uint32_t i, nr_large_offset = 0;
 477         size_t written = 0;
 478
 479         for (i = 0; i < nr_objects; i++) {
 480                 struct pack_midx_entry *obj = list++;
 481
 482                 hashwrite_be32(f, obj->pack_int_id);
 483
 484                 if (large_offset_needed && obj->offset >> 31)
 485                         hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
 486                 else if (!large_offset_needed && obj->offset >> 32)
 487                         BUG("object %s requires a large offset (%"PRIx64") but the MIDX is not writing large offsets!",
 488                             oid_to_hex(&obj->oid),
 489                             obj->offset);
 490                 else
 491                         hashwrite_be32(f, (uint32_t)obj->offset);
 492
 493                 written += MIDX_CHUNK_OFFSET_WIDTH;
 494         }
 495
 496         return written;
 497 }
 498
 499 static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_offset,
 500                                        struct pack_midx_entry *objects, uint32_t nr_objects)
 501 {
 502         struct pack_midx_entry *list = objects;
 503         size_t written = 0;
 504
 505         while (nr_large_offset) {
 506                 struct pack_midx_entry *obj = list++;
 507                 uint64_t offset = obj->offset;
 508
 509                 if (!(offset >> 31))
 510                         continue;
 511
 512                 hashwrite_be32(f, offset >> 32);
 513                 hashwrite_be32(f, offset & 0xffffffffUL);
 514                 written += 2 * sizeof(uint32_t);
 515
 516                 nr_large_offset--;
 517         }
 518
 519         return written;
 520 }
 521
 522 int write_midx_file(const char *object_dir)
 523 {
 524         unsigned char cur_chunk, num_chunks = 0;
 525         char *midx_name;
 526         uint32_t i;
 527         struct hashfile *f = NULL;
 528         struct lock_file lk;
 529         struct pack_list packs;
 530         uint32_t *pack_perm = NULL;
 531         uint64_t written = 0;
 532         uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
 533         uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
 534         uint32_t nr_entries, num_large_offsets = 0;
 535         struct pack_midx_entry *entries = NULL;
 536         int large_offsets_needed = 0;
 537
 538         midx_name = get_midx_filename(object_dir);
 539         if (safe_create_leading_directories(midx_name)) {
 540                 UNLEAK(midx_name);
 541                 die_errno(_("unable to create leading directories of %s"),
 542                           midx_name);
 543         }
 544
 545         packs.nr = 0;
 546         packs.alloc_list = 16;
 547         packs.alloc_names = 16;
 548         packs.list = NULL;
 549         packs.pack_name_concat_len = 0;
 550         ALLOC_ARRAY(packs.list, packs.alloc_list);
 551         ALLOC_ARRAY(packs.names, packs.alloc_names);
 552
 553         for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 554
 555         if (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 556                 packs.pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
 557                                               (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
 558
 559         ALLOC_ARRAY(pack_perm, packs.nr);
 560         sort_packs_by_name(packs.names, packs.nr, pack_perm);
 561
 562         entries = get_sorted_entries(packs.list, pack_perm, packs.nr, &nr_entries);
 563         for (i = 0; i < nr_entries; i++) {
 564                 if (entries[i].offset > 0x7fffffff)
 565                         num_large_offsets++;
 566                 if (entries[i].offset > 0xffffffff)
 567                         large_offsets_needed = 1;
 568         }
 569
 570         hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
 571         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 572         FREE_AND_NULL(midx_name);
 573
 574         cur_chunk = 0;
 575         num_chunks = large_offsets_needed ? 5 : 4;
 576
 577         written = write_midx_header(f, num_chunks, packs.nr);
 578
 579         chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
 580         chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
 581
 582         cur_chunk++;
 583         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
 584         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
 585
 586         cur_chunk++;
 587         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
 588         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
 589
 590         cur_chunk++;
 591         chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
 592         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
 593
 594         cur_chunk++;
 595         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
 596         if (large_offsets_needed) {
 597                 chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
 598
 599                 cur_chunk++;
 600                 chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
 601                                            num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
 602         }
 603
 604         chunk_ids[cur_chunk] = 0;
 605
 606         for (i = 0; i <= num_chunks; i++) {
 607                 if (i && chunk_offsets[i] < chunk_offsets[i - 1])
 608                         BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
 609                             chunk_offsets[i - 1],
 610                             chunk_offsets[i]);
 611
 612                 if (chunk_offsets[i] % MIDX_CHUNK_ALIGNMENT)
 613                         BUG("chunk offset %"PRIu64" is not properly aligned",
 614                             chunk_offsets[i]);
 615
 616                 hashwrite_be32(f, chunk_ids[i]);
 617                 hashwrite_be32(f, chunk_offsets[i] >> 32);
 618                 hashwrite_be32(f, chunk_offsets[i]);
 619
 620                 written += MIDX_CHUNKLOOKUP_WIDTH;
 621         }
 622
 623         for (i = 0; i < num_chunks; i++) {
 624                 if (written != chunk_offsets[i])
 625                         BUG("incorrect chunk offset (%"PRIu64" != %"PRIu64") for chunk id %"PRIx32,
 626                             chunk_offsets[i],
 627                             written,
 628                             chunk_ids[i]);
 629
 630                 switch (chunk_ids[i]) {
 631                         case MIDX_CHUNKID_PACKNAMES:
 632                                 written += write_midx_pack_names(f, packs.names, packs.nr);
 633                                 break;
 634
 635                         case MIDX_CHUNKID_OIDFANOUT:
 636                                 written += write_midx_oid_fanout(f, entries, nr_entries);
 637                                 break;
 638
 639                         case MIDX_CHUNKID_OIDLOOKUP:
 640                                 written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
 641                                 break;
 642
 643                         case MIDX_CHUNKID_OBJECTOFFSETS:
 644                                 written += write_midx_object_offsets(f, large_offsets_needed, entries, nr_entries);
 645                                 break;
 646
 647                         case MIDX_CHUNKID_LARGEOFFSETS:
 648                                 written += write_midx_large_offsets(f, num_large_offsets, entries, nr_entries);
 649                                 break;
 650
 651                         default:
 652                                 BUG("trying to write unknown chunk id %"PRIx32,
 653                                     chunk_ids[i]);
 654                 }
 655         }
 656
 657         if (written != chunk_offsets[num_chunks])
 658                 BUG("incorrect final offset %"PRIu64" != %"PRIu64,
 659                     written,
 660                     chunk_offsets[num_chunks]);
 661
 662         finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
 663         commit_lock_file(&lk);
 664
 665         for (i = 0; i < packs.nr; i++) {
 666                 if (packs.list[i]) {
 667                         close_pack(packs.list[i]);
 668                         free(packs.list[i]);
 669                 }
 670                 free(packs.names[i]);
 671         }
 672
 673         free(packs.list);
 674         free(packs.names);
 675         free(entries);
 676         return 0;
 677 }