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

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "csum-file.h"
   4 #include "dir.h"
   5 #include "lockfile.h"
   6 #include "packfile.h"
   7 #include "object-store.h"
   8 #include "sha1-lookup.h"
   9 #include "midx.h"
  10
  11 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
  12 #define MIDX_VERSION 1
  13 #define MIDX_BYTE_FILE_VERSION 4
  14 #define MIDX_BYTE_HASH_VERSION 5
  15 #define MIDX_BYTE_NUM_CHUNKS 6
  16 #define MIDX_BYTE_NUM_PACKS 8
  17 #define MIDX_HASH_VERSION 1
  18 #define MIDX_HEADER_SIZE 12
  19 #define MIDX_HASH_LEN 20
  20 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
  21
  22 #define MIDX_MAX_CHUNKS 5
  23 #define MIDX_CHUNK_ALIGNMENT 4
  24 #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
  25 #define MIDX_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  26 #define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  27 #define MIDX_CHUNKID_OBJECTOFFSETS 0x4f4f4646 /* "OOFF" */
  28 #define MIDX_CHUNKID_LARGEOFFSETS 0x4c4f4646 /* "LOFF" */
  29 #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
  30 #define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
  31 #define MIDX_CHUNK_OFFSET_WIDTH (2 * sizeof(uint32_t))
  32 #define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
  33 #define MIDX_LARGE_OFFSET_NEEDED 0x80000000
  34
  35 static char *get_midx_filename(const char *object_dir)
  36 {
  37         return xstrfmt("%s/pack/multi-pack-index", object_dir);
  38 }
  39
  40 struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local)
  41 {
  42         struct multi_pack_index *m = NULL;
  43         int fd;
  44         struct stat st;
  45         size_t midx_size;
  46         void *midx_map = NULL;
  47         uint32_t hash_version;
  48         char *midx_name = get_midx_filename(object_dir);
  49         uint32_t i;
  50         const char *cur_pack_name;
  51
  52         fd = git_open(midx_name);
  53
  54         if (fd < 0)
  55                 goto cleanup_fail;
  56         if (fstat(fd, &st)) {
  57                 error_errno(_("failed to read %s"), midx_name);
  58                 goto cleanup_fail;
  59         }
  60
  61         midx_size = xsize_t(st.st_size);
  62
  63         if (midx_size < MIDX_MIN_SIZE) {
  64                 error(_("multi-pack-index file %s is too small"), midx_name);
  65                 goto cleanup_fail;
  66         }
  67
  68         FREE_AND_NULL(midx_name);
  69
  70         midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
  71
  72         FLEX_ALLOC_MEM(m, object_dir, object_dir, strlen(object_dir));
  73         m->fd = fd;
  74         m->data = midx_map;
  75         m->data_len = midx_size;
  76         m->local = local;
  77
  78         m->signature = get_be32(m->data);
  79         if (m->signature != MIDX_SIGNATURE) {
  80                 error(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
  81                       m->signature, MIDX_SIGNATURE);
  82                 goto cleanup_fail;
  83         }
  84
  85         m->version = m->data[MIDX_BYTE_FILE_VERSION];
  86         if (m->version != MIDX_VERSION) {
  87                 error(_("multi-pack-index version %d not recognized"),
  88                       m->version);
  89                 goto cleanup_fail;
  90         }
  91
  92         hash_version = m->data[MIDX_BYTE_HASH_VERSION];
  93         if (hash_version != MIDX_HASH_VERSION) {
  94                 error(_("hash version %u does not match"), hash_version);
  95                 goto cleanup_fail;
  96         }
  97         m->hash_len = MIDX_HASH_LEN;
  98
  99         m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
 100
 101         m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
 102
 103         for (i = 0; i < m->num_chunks; i++) {
 104                 uint32_t chunk_id = get_be32(m->data + MIDX_HEADER_SIZE +
 105                                              MIDX_CHUNKLOOKUP_WIDTH * i);
 106                 uint64_t chunk_offset = get_be64(m->data + MIDX_HEADER_SIZE + 4 +
 107                                                  MIDX_CHUNKLOOKUP_WIDTH * i);
 108
 109                 switch (chunk_id) {
 110                         case MIDX_CHUNKID_PACKNAMES:
 111                                 m->chunk_pack_names = m->data + chunk_offset;
 112                                 break;
 113
 114                         case MIDX_CHUNKID_OIDFANOUT:
 115                                 m->chunk_oid_fanout = (uint32_t *)(m->data + chunk_offset);
 116                                 break;
 117
 118                         case MIDX_CHUNKID_OIDLOOKUP:
 119                                 m->chunk_oid_lookup = m->data + chunk_offset;
 120                                 break;
 121
 122                         case MIDX_CHUNKID_OBJECTOFFSETS:
 123                                 m->chunk_object_offsets = m->data + chunk_offset;
 124                                 break;
 125
 126                         case MIDX_CHUNKID_LARGEOFFSETS:
 127                                 m->chunk_large_offsets = m->data + chunk_offset;
 128                                 break;
 129
 130                         case 0:
 131                                 die(_("terminating multi-pack-index chunk id appears earlier than expected"));
 132                                 break;
 133
 134                         default:
 135                                 /*
 136                                  * Do nothing on unrecognized chunks, allowing future
 137                                  * extensions to add optional chunks.
 138                                  */
 139                                 break;
 140                 }
 141         }
 142
 143         if (!m->chunk_pack_names)
 144                 die(_("multi-pack-index missing required pack-name chunk"));
 145         if (!m->chunk_oid_fanout)
 146                 die(_("multi-pack-index missing required OID fanout chunk"));
 147         if (!m->chunk_oid_lookup)
 148                 die(_("multi-pack-index missing required OID lookup chunk"));
 149         if (!m->chunk_object_offsets)
 150                 die(_("multi-pack-index missing required object offsets chunk"));
 151
 152         m->num_objects = ntohl(m->chunk_oid_fanout[255]);
 153
 154         m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
 155         m->packs = xcalloc(m->num_packs, sizeof(*m->packs));
 156
 157         cur_pack_name = (const char *)m->chunk_pack_names;
 158         for (i = 0; i < m->num_packs; i++) {
 159                 m->pack_names[i] = cur_pack_name;
 160
 161                 cur_pack_name += strlen(cur_pack_name) + 1;
 162
 163                 if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0) {
 164                         error(_("multi-pack-index pack names out of order: '%s' before '%s'"),
 165                               m->pack_names[i - 1],
 166                               m->pack_names[i]);
 167                         goto cleanup_fail;
 168                 }
 169         }
 170
 171         return m;
 172
 173 cleanup_fail:
 174         free(m);
 175         free(midx_name);
 176         if (midx_map)
 177                 munmap(midx_map, midx_size);
 178         if (0 <= fd)
 179                 close(fd);
 180         return NULL;
 181 }
 182
 183 void close_midx(struct multi_pack_index *m)
 184 {
 185         uint32_t i;
 186
 187         if (!m)
 188                 return;
 189
 190         munmap((unsigned char *)m->data, m->data_len);
 191         close(m->fd);
 192         m->fd = -1;
 193
 194         for (i = 0; i < m->num_packs; i++) {
 195                 if (m->packs[i]) {
 196                         close_pack(m->packs[i]);
 197                         free(m->packs[i]);
 198                 }
 199         }
 200         FREE_AND_NULL(m->packs);
 201         FREE_AND_NULL(m->pack_names);
 202 }
 203
 204 int prepare_midx_pack(struct multi_pack_index *m, uint32_t pack_int_id)
 205 {
 206         struct strbuf pack_name = STRBUF_INIT;
 207
 208         if (pack_int_id >= m->num_packs)
 209                 BUG("bad pack-int-id");
 210
 211         if (m->packs[pack_int_id])
 212                 return 0;
 213
 214         strbuf_addf(&pack_name, "%s/pack/%s", m->object_dir,
 215                     m->pack_names[pack_int_id]);
 216
 217         m->packs[pack_int_id] = add_packed_git(pack_name.buf, pack_name.len, m->local);
 218         strbuf_release(&pack_name);
 219         return !m->packs[pack_int_id];
 220 }
 221
 222 int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
 223 {
 224         return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
 225                             MIDX_HASH_LEN, result);
 226 }
 227
 228 struct object_id *nth_midxed_object_oid(struct object_id *oid,
 229                                         struct multi_pack_index *m,
 230                                         uint32_t n)
 231 {
 232         if (n >= m->num_objects)
 233                 return NULL;
 234
 235         hashcpy(oid->hash, m->chunk_oid_lookup + m->hash_len * n);
 236         return oid;
 237 }
 238
 239 static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
 240 {
 241         const unsigned char *offset_data;
 242         uint32_t offset32;
 243
 244         offset_data = m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH;
 245         offset32 = get_be32(offset_data + sizeof(uint32_t));
 246
 247         if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
 248                 if (sizeof(offset32) < sizeof(uint64_t))
 249                         die(_("multi-pack-index stores a 64-bit offset, but off_t is too small"));
 250
 251                 offset32 ^= MIDX_LARGE_OFFSET_NEEDED;
 252                 return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32);
 253         }
 254
 255         return offset32;
 256 }
 257
 258 static uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
 259 {
 260         return get_be32(m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH);
 261 }
 262
 263 static int nth_midxed_pack_entry(struct multi_pack_index *m, struct pack_entry *e, uint32_t pos)
 264 {
 265         uint32_t pack_int_id;
 266         struct packed_git *p;
 267
 268         if (pos >= m->num_objects)
 269                 return 0;
 270
 271         pack_int_id = nth_midxed_pack_int_id(m, pos);
 272
 273         if (prepare_midx_pack(m, pack_int_id))
 274                 die(_("error preparing packfile from multi-pack-index"));
 275         p = m->packs[pack_int_id];
 276
 277         /*
 278         * We are about to tell the caller where they can locate the
 279         * requested object.  We better make sure the packfile is
 280         * still here and can be accessed before supplying that
 281         * answer, as it may have been deleted since the MIDX was
 282         * loaded!
 283         */
 284         if (!is_pack_valid(p))
 285                 return 0;
 286
 287         if (p->num_bad_objects) {
 288                 uint32_t i;
 289                 struct object_id oid;
 290                 nth_midxed_object_oid(&oid, m, pos);
 291                 for (i = 0; i < p->num_bad_objects; i++)
 292                         if (!hashcmp(oid.hash,
 293                                      p->bad_object_sha1 + the_hash_algo->rawsz * i))
 294                                 return 0;
 295         }
 296
 297         e->offset = nth_midxed_offset(m, pos);
 298         e->p = p;
 299
 300         return 1;
 301 }
 302
 303 int fill_midx_entry(const struct object_id *oid, struct pack_entry *e, struct multi_pack_index *m)
 304 {
 305         uint32_t pos;
 306
 307         if (!bsearch_midx(oid, m, &pos))
 308                 return 0;
 309
 310         return nth_midxed_pack_entry(m, e, pos);
 311 }
 312
 313 int midx_contains_pack(struct multi_pack_index *m, const char *idx_name)
 314 {
 315         uint32_t first = 0, last = m->num_packs;
 316
 317         while (first < last) {
 318                 uint32_t mid = first + (last - first) / 2;
 319                 const char *current;
 320                 int cmp;
 321
 322                 current = m->pack_names[mid];
 323                 cmp = strcmp(idx_name, current);
 324                 if (!cmp)
 325                         return 1;
 326                 if (cmp > 0) {
 327                         first = mid + 1;
 328                         continue;
 329                 }
 330                 last = mid;
 331         }
 332
 333         return 0;
 334 }
 335
 336 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local)
 337 {
 338         struct multi_pack_index *m;
 339         struct multi_pack_index *m_search;
 340         int config_value;
 341         static int env_value = -1;
 342
 343         if (env_value < 0)
 344                 env_value = git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0);
 345
 346         if (!env_value &&
 347             (repo_config_get_bool(r, "core.multipackindex", &config_value) ||
 348             !config_value))
 349                 return 0;
 350
 351         for (m_search = r->objects->multi_pack_index; m_search; m_search = m_search->next)
 352                 if (!strcmp(object_dir, m_search->object_dir))
 353                         return 1;
 354
 355         m = load_multi_pack_index(object_dir, local);
 356
 357         if (m) {
 358                 m->next = r->objects->multi_pack_index;
 359                 r->objects->multi_pack_index = m;
 360                 return 1;
 361         }
 362
 363         return 0;
 364 }
 365
 366 static size_t write_midx_header(struct hashfile *f,
 367                                 unsigned char num_chunks,
 368                                 uint32_t num_packs)
 369 {
 370         unsigned char byte_values[4];
 371
 372         hashwrite_be32(f, MIDX_SIGNATURE);
 373         byte_values[0] = MIDX_VERSION;
 374         byte_values[1] = MIDX_HASH_VERSION;
 375         byte_values[2] = num_chunks;
 376         byte_values[3] = 0; /* unused */
 377         hashwrite(f, byte_values, sizeof(byte_values));
 378         hashwrite_be32(f, num_packs);
 379
 380         return MIDX_HEADER_SIZE;
 381 }
 382
 383 struct pack_list {
 384         struct packed_git **list;
 385         char **names;
 386         uint32_t nr;
 387         uint32_t alloc_list;
 388         uint32_t alloc_names;
 389         size_t pack_name_concat_len;
 390         struct multi_pack_index *m;
 391 };
 392
 393 static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 394                              const char *file_name, void *data)
 395 {
 396         struct pack_list *packs = (struct pack_list *)data;
 397
 398         if (ends_with(file_name, ".idx")) {
 399                 if (packs->m && midx_contains_pack(packs->m, file_name))
 400                         return;
 401
 402                 ALLOC_GROW(packs->list, packs->nr + 1, packs->alloc_list);
 403                 ALLOC_GROW(packs->names, packs->nr + 1, packs->alloc_names);
 404
 405                 packs->list[packs->nr] = add_packed_git(full_path,
 406                                                         full_path_len,
 407                                                         0);
 408
 409                 if (!packs->list[packs->nr]) {
 410                         warning(_("failed to add packfile '%s'"),
 411                                 full_path);
 412                         return;
 413                 }
 414
 415                 if (open_pack_index(packs->list[packs->nr])) {
 416                         warning(_("failed to open pack-index '%s'"),
 417                                 full_path);
 418                         close_pack(packs->list[packs->nr]);
 419                         FREE_AND_NULL(packs->list[packs->nr]);
 420                         return;
 421                 }
 422
 423                 packs->names[packs->nr] = xstrdup(file_name);
 424                 packs->pack_name_concat_len += strlen(file_name) + 1;
 425                 packs->nr++;
 426         }
 427 }
 428
 429 struct pack_pair {
 430         uint32_t pack_int_id;
 431         char *pack_name;
 432 };
 433
 434 static int pack_pair_compare(const void *_a, const void *_b)
 435 {
 436         struct pack_pair *a = (struct pack_pair *)_a;
 437         struct pack_pair *b = (struct pack_pair *)_b;
 438         return strcmp(a->pack_name, b->pack_name);
 439 }
 440
 441 static void sort_packs_by_name(char **pack_names, uint32_t nr_packs, uint32_t *perm)
 442 {
 443         uint32_t i;
 444         struct pack_pair *pairs;
 445
 446         ALLOC_ARRAY(pairs, nr_packs);
 447
 448         for (i = 0; i < nr_packs; i++) {
 449                 pairs[i].pack_int_id = i;
 450                 pairs[i].pack_name = pack_names[i];
 451         }
 452
 453         QSORT(pairs, nr_packs, pack_pair_compare);
 454
 455         for (i = 0; i < nr_packs; i++) {
 456                 pack_names[i] = pairs[i].pack_name;
 457                 perm[pairs[i].pack_int_id] = i;
 458         }
 459
 460         free(pairs);
 461 }
 462
 463 struct pack_midx_entry {
 464         struct object_id oid;
 465         uint32_t pack_int_id;
 466         time_t pack_mtime;
 467         uint64_t offset;
 468 };
 469
 470 static int midx_oid_compare(const void *_a, const void *_b)
 471 {
 472         const struct pack_midx_entry *a = (const struct pack_midx_entry *)_a;
 473         const struct pack_midx_entry *b = (const struct pack_midx_entry *)_b;
 474         int cmp = oidcmp(&a->oid, &b->oid);
 475
 476         if (cmp)
 477                 return cmp;
 478
 479         if (a->pack_mtime > b->pack_mtime)
 480                 return -1;
 481         else if (a->pack_mtime < b->pack_mtime)
 482                 return 1;
 483
 484         return a->pack_int_id - b->pack_int_id;
 485 }
 486
 487 static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
 488                                       uint32_t *pack_perm,
 489                                       struct pack_midx_entry *e,
 490                                       uint32_t pos)
 491 {
 492         if (pos >= m->num_objects)
 493                 return 1;
 494
 495         nth_midxed_object_oid(&e->oid, m, pos);
 496         e->pack_int_id = pack_perm[nth_midxed_pack_int_id(m, pos)];
 497         e->offset = nth_midxed_offset(m, pos);
 498
 499         /* consider objects in midx to be from "old" packs */
 500         e->pack_mtime = 0;
 501         return 0;
 502 }
 503
 504 static void fill_pack_entry(uint32_t pack_int_id,
 505                             struct packed_git *p,
 506                             uint32_t cur_object,
 507                             struct pack_midx_entry *entry)
 508 {
 509         if (!nth_packed_object_oid(&entry->oid, p, cur_object))
 510                 die(_("failed to locate object %d in packfile"), cur_object);
 511
 512         entry->pack_int_id = pack_int_id;
 513         entry->pack_mtime = p->mtime;
 514
 515         entry->offset = nth_packed_object_offset(p, cur_object);
 516 }
 517
 518 /*
 519  * It is possible to artificially get into a state where there are many
 520  * duplicate copies of objects. That can create high memory pressure if
 521  * we are to create a list of all objects before de-duplication. To reduce
 522  * this memory pressure without a significant performance drop, automatically
 523  * group objects by the first byte of their object id. Use the IDX fanout
 524  * tables to group the data, copy to a local array, then sort.
 525  *
 526  * Copy only the de-duplicated entries (selected by most-recent modified time
 527  * of a packfile containing the object).
 528  */
 529 static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 530                                                   struct packed_git **p,
 531                                                   uint32_t *perm,
 532                                                   uint32_t nr_packs,
 533                                                   uint32_t *nr_objects)
 534 {
 535         uint32_t cur_fanout, cur_pack, cur_object;
 536         uint32_t alloc_fanout, alloc_objects, total_objects = 0;
 537         struct pack_midx_entry *entries_by_fanout = NULL;
 538         struct pack_midx_entry *deduplicated_entries = NULL;
 539         uint32_t start_pack = m ? m->num_packs : 0;
 540
 541         for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
 542                 total_objects += p[cur_pack]->num_objects;
 543
 544         /*
 545          * As we de-duplicate by fanout value, we expect the fanout
 546          * slices to be evenly distributed, with some noise. Hence,
 547          * allocate slightly more than one 256th.
 548          */
 549         alloc_objects = alloc_fanout = total_objects > 3200 ? total_objects / 200 : 16;
 550
 551         ALLOC_ARRAY(entries_by_fanout, alloc_fanout);
 552         ALLOC_ARRAY(deduplicated_entries, alloc_objects);
 553         *nr_objects = 0;
 554
 555         for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
 556                 uint32_t nr_fanout = 0;
 557
 558                 if (m) {
 559                         uint32_t start = 0, end;
 560
 561                         if (cur_fanout)
 562                                 start = ntohl(m->chunk_oid_fanout[cur_fanout - 1]);
 563                         end = ntohl(m->chunk_oid_fanout[cur_fanout]);
 564
 565                         for (cur_object = start; cur_object < end; cur_object++) {
 566                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 567                                 nth_midxed_pack_midx_entry(m, perm,
 568                                                            &entries_by_fanout[nr_fanout],
 569                                                            cur_object);
 570                                 nr_fanout++;
 571                         }
 572                 }
 573
 574                 for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++) {
 575                         uint32_t start = 0, end;
 576
 577                         if (cur_fanout)
 578                                 start = get_pack_fanout(p[cur_pack], cur_fanout - 1);
 579                         end = get_pack_fanout(p[cur_pack], cur_fanout);
 580
 581                         for (cur_object = start; cur_object < end; cur_object++) {
 582                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 583                                 fill_pack_entry(perm[cur_pack], p[cur_pack], cur_object, &entries_by_fanout[nr_fanout]);
 584                                 nr_fanout++;
 585                         }
 586                 }
 587
 588                 QSORT(entries_by_fanout, nr_fanout, midx_oid_compare);
 589
 590                 /*
 591                  * The batch is now sorted by OID and then mtime (descending).
 592                  * Take only the first duplicate.
 593                  */
 594                 for (cur_object = 0; cur_object < nr_fanout; cur_object++) {
 595                         if (cur_object && !oidcmp(&entries_by_fanout[cur_object - 1].oid,
 596                                                   &entries_by_fanout[cur_object].oid))
 597                                 continue;
 598
 599                         ALLOC_GROW(deduplicated_entries, *nr_objects + 1, alloc_objects);
 600                         memcpy(&deduplicated_entries[*nr_objects],
 601                                &entries_by_fanout[cur_object],
 602                                sizeof(struct pack_midx_entry));
 603                         (*nr_objects)++;
 604                 }
 605         }
 606
 607         free(entries_by_fanout);
 608         return deduplicated_entries;
 609 }
 610
 611 static size_t write_midx_pack_names(struct hashfile *f,
 612                                     char **pack_names,
 613                                     uint32_t num_packs)
 614 {
 615         uint32_t i;
 616         unsigned char padding[MIDX_CHUNK_ALIGNMENT];
 617         size_t written = 0;
 618
 619         for (i = 0; i < num_packs; i++) {
 620                 size_t writelen = strlen(pack_names[i]) + 1;
 621
 622                 if (i && strcmp(pack_names[i], pack_names[i - 1]) <= 0)
 623                         BUG("incorrect pack-file order: %s before %s",
 624                             pack_names[i - 1],
 625                             pack_names[i]);
 626
 627                 hashwrite(f, pack_names[i], writelen);
 628                 written += writelen;
 629         }
 630
 631         /* add padding to be aligned */
 632         i = MIDX_CHUNK_ALIGNMENT - (written % MIDX_CHUNK_ALIGNMENT);
 633         if (i < MIDX_CHUNK_ALIGNMENT) {
 634                 memset(padding, 0, sizeof(padding));
 635                 hashwrite(f, padding, i);
 636                 written += i;
 637         }
 638
 639         return written;
 640 }
 641
 642 static size_t write_midx_oid_fanout(struct hashfile *f,
 643                                     struct pack_midx_entry *objects,
 644                                     uint32_t nr_objects)
 645 {
 646         struct pack_midx_entry *list = objects;
 647         struct pack_midx_entry *last = objects + nr_objects;
 648         uint32_t count = 0;
 649         uint32_t i;
 650
 651         /*
 652         * Write the first-level table (the list is sorted,
 653         * but we use a 256-entry lookup to be able to avoid
 654         * having to do eight extra binary search iterations).
 655         */
 656         for (i = 0; i < 256; i++) {
 657                 struct pack_midx_entry *next = list;
 658
 659                 while (next < last && next->oid.hash[0] == i) {
 660                         count++;
 661                         next++;
 662                 }
 663
 664                 hashwrite_be32(f, count);
 665                 list = next;
 666         }
 667
 668         return MIDX_CHUNK_FANOUT_SIZE;
 669 }
 670
 671 static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
 672                                     struct pack_midx_entry *objects,
 673                                     uint32_t nr_objects)
 674 {
 675         struct pack_midx_entry *list = objects;
 676         uint32_t i;
 677         size_t written = 0;
 678
 679         for (i = 0; i < nr_objects; i++) {
 680                 struct pack_midx_entry *obj = list++;
 681
 682                 if (i < nr_objects - 1) {
 683                         struct pack_midx_entry *next = list;
 684                         if (oidcmp(&obj->oid, &next->oid) >= 0)
 685                                 BUG("OIDs not in order: %s >= %s",
 686                                     oid_to_hex(&obj->oid),
 687                                     oid_to_hex(&next->oid));
 688                 }
 689
 690                 hashwrite(f, obj->oid.hash, (int)hash_len);
 691                 written += hash_len;
 692         }
 693
 694         return written;
 695 }
 696
 697 static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
 698                                         struct pack_midx_entry *objects, uint32_t nr_objects)
 699 {
 700         struct pack_midx_entry *list = objects;
 701         uint32_t i, nr_large_offset = 0;
 702         size_t written = 0;
 703
 704         for (i = 0; i < nr_objects; i++) {
 705                 struct pack_midx_entry *obj = list++;
 706
 707                 hashwrite_be32(f, obj->pack_int_id);
 708
 709                 if (large_offset_needed && obj->offset >> 31)
 710                         hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
 711                 else if (!large_offset_needed && obj->offset >> 32)
 712                         BUG("object %s requires a large offset (%"PRIx64") but the MIDX is not writing large offsets!",
 713                             oid_to_hex(&obj->oid),
 714                             obj->offset);
 715                 else
 716                         hashwrite_be32(f, (uint32_t)obj->offset);
 717
 718                 written += MIDX_CHUNK_OFFSET_WIDTH;
 719         }
 720
 721         return written;
 722 }
 723
 724 static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_offset,
 725                                        struct pack_midx_entry *objects, uint32_t nr_objects)
 726 {
 727         struct pack_midx_entry *list = objects;
 728         size_t written = 0;
 729
 730         while (nr_large_offset) {
 731                 struct pack_midx_entry *obj = list++;
 732                 uint64_t offset = obj->offset;
 733
 734                 if (!(offset >> 31))
 735                         continue;
 736
 737                 hashwrite_be32(f, offset >> 32);
 738                 hashwrite_be32(f, offset & 0xffffffffUL);
 739                 written += 2 * sizeof(uint32_t);
 740
 741                 nr_large_offset--;
 742         }
 743
 744         return written;
 745 }
 746
 747 int write_midx_file(const char *object_dir)
 748 {
 749         unsigned char cur_chunk, num_chunks = 0;
 750         char *midx_name;
 751         uint32_t i;
 752         struct hashfile *f = NULL;
 753         struct lock_file lk;
 754         struct pack_list packs;
 755         uint32_t *pack_perm = NULL;
 756         uint64_t written = 0;
 757         uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
 758         uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
 759         uint32_t nr_entries, num_large_offsets = 0;
 760         struct pack_midx_entry *entries = NULL;
 761         int large_offsets_needed = 0;
 762
 763         midx_name = get_midx_filename(object_dir);
 764         if (safe_create_leading_directories(midx_name)) {
 765                 UNLEAK(midx_name);
 766                 die_errno(_("unable to create leading directories of %s"),
 767                           midx_name);
 768         }
 769
 770         packs.m = load_multi_pack_index(object_dir, 1);
 771
 772         packs.nr = 0;
 773         packs.alloc_list = packs.m ? packs.m->num_packs : 16;
 774         packs.alloc_names = packs.alloc_list;
 775         packs.list = NULL;
 776         packs.names = NULL;
 777         packs.pack_name_concat_len = 0;
 778         ALLOC_ARRAY(packs.list, packs.alloc_list);
 779         ALLOC_ARRAY(packs.names, packs.alloc_names);
 780
 781         if (packs.m) {
 782                 for (i = 0; i < packs.m->num_packs; i++) {
 783                         ALLOC_GROW(packs.list, packs.nr + 1, packs.alloc_list);
 784                         ALLOC_GROW(packs.names, packs.nr + 1, packs.alloc_names);
 785
 786                         packs.list[packs.nr] = NULL;
 787                         packs.names[packs.nr] = xstrdup(packs.m->pack_names[i]);
 788                         packs.pack_name_concat_len += strlen(packs.names[packs.nr]) + 1;
 789                         packs.nr++;
 790                 }
 791         }
 792
 793         for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 794
 795         if (packs.m && packs.nr == packs.m->num_packs)
 796                 goto cleanup;
 797
 798         if (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 799                 packs.pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
 800                                               (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
 801
 802         ALLOC_ARRAY(pack_perm, packs.nr);
 803         sort_packs_by_name(packs.names, packs.nr, pack_perm);
 804
 805         entries = get_sorted_entries(packs.m, packs.list, pack_perm, packs.nr, &nr_entries);
 806
 807         for (i = 0; i < nr_entries; i++) {
 808                 if (entries[i].offset > 0x7fffffff)
 809                         num_large_offsets++;
 810                 if (entries[i].offset > 0xffffffff)
 811                         large_offsets_needed = 1;
 812         }
 813
 814         hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
 815         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 816         FREE_AND_NULL(midx_name);
 817
 818         if (packs.m)
 819                 close_midx(packs.m);
 820
 821         cur_chunk = 0;
 822         num_chunks = large_offsets_needed ? 5 : 4;
 823
 824         written = write_midx_header(f, num_chunks, packs.nr);
 825
 826         chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
 827         chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
 828
 829         cur_chunk++;
 830         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
 831         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
 832
 833         cur_chunk++;
 834         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
 835         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
 836
 837         cur_chunk++;
 838         chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
 839         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
 840
 841         cur_chunk++;
 842         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
 843         if (large_offsets_needed) {
 844                 chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
 845
 846                 cur_chunk++;
 847                 chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
 848                                            num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
 849         }
 850
 851         chunk_ids[cur_chunk] = 0;
 852
 853         for (i = 0; i <= num_chunks; i++) {
 854                 if (i && chunk_offsets[i] < chunk_offsets[i - 1])
 855                         BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
 856                             chunk_offsets[i - 1],
 857                             chunk_offsets[i]);
 858
 859                 if (chunk_offsets[i] % MIDX_CHUNK_ALIGNMENT)
 860                         BUG("chunk offset %"PRIu64" is not properly aligned",
 861                             chunk_offsets[i]);
 862
 863                 hashwrite_be32(f, chunk_ids[i]);
 864                 hashwrite_be32(f, chunk_offsets[i] >> 32);
 865                 hashwrite_be32(f, chunk_offsets[i]);
 866
 867                 written += MIDX_CHUNKLOOKUP_WIDTH;
 868         }
 869
 870         for (i = 0; i < num_chunks; i++) {
 871                 if (written != chunk_offsets[i])
 872                         BUG("incorrect chunk offset (%"PRIu64" != %"PRIu64") for chunk id %"PRIx32,
 873                             chunk_offsets[i],
 874                             written,
 875                             chunk_ids[i]);
 876
 877                 switch (chunk_ids[i]) {
 878                         case MIDX_CHUNKID_PACKNAMES:
 879                                 written += write_midx_pack_names(f, packs.names, packs.nr);
 880                                 break;
 881
 882                         case MIDX_CHUNKID_OIDFANOUT:
 883                                 written += write_midx_oid_fanout(f, entries, nr_entries);
 884                                 break;
 885
 886                         case MIDX_CHUNKID_OIDLOOKUP:
 887                                 written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
 888                                 break;
 889
 890                         case MIDX_CHUNKID_OBJECTOFFSETS:
 891                                 written += write_midx_object_offsets(f, large_offsets_needed, entries, nr_entries);
 892                                 break;
 893
 894                         case MIDX_CHUNKID_LARGEOFFSETS:
 895                                 written += write_midx_large_offsets(f, num_large_offsets, entries, nr_entries);
 896                                 break;
 897
 898                         default:
 899                                 BUG("trying to write unknown chunk id %"PRIx32,
 900                                     chunk_ids[i]);
 901                 }
 902         }
 903
 904         if (written != chunk_offsets[num_chunks])
 905                 BUG("incorrect final offset %"PRIu64" != %"PRIu64,
 906                     written,
 907                     chunk_offsets[num_chunks]);
 908
 909         finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
 910         commit_lock_file(&lk);
 911
 912 cleanup:
 913         for (i = 0; i < packs.nr; i++) {
 914                 if (packs.list[i]) {
 915                         close_pack(packs.list[i]);
 916                         free(packs.list[i]);
 917                 }
 918                 free(packs.names[i]);
 919         }
 920
 921         free(packs.list);
 922         free(packs.names);
 923         free(entries);
 924         free(pack_perm);
 925         free(midx_name);
 926         return 0;
 927 }
 928
 929 void clear_midx_file(struct repository *r)
 930 {
 931         char *midx = get_midx_filename(r->objects->objectdir);
 932
 933         if (r->objects && r->objects->multi_pack_index) {
 934                 close_midx(r->objects->multi_pack_index);
 935                 r->objects->multi_pack_index = NULL;
 936         }
 937
 938         if (remove_path(midx)) {
 939                 UNLEAK(midx);
 940                 die(_("failed to clear multi-pack-index at %s"), midx);
 941         }
 942
 943         free(midx);
 944 }