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 #include "progress.h"
  11 #include "trace2.h"
  12
  13 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
  14 #define MIDX_VERSION 1
  15 #define MIDX_BYTE_FILE_VERSION 4
  16 #define MIDX_BYTE_HASH_VERSION 5
  17 #define MIDX_BYTE_NUM_CHUNKS 6
  18 #define MIDX_BYTE_NUM_PACKS 8
  19 #define MIDX_HASH_VERSION 1
  20 #define MIDX_HEADER_SIZE 12
  21 #define MIDX_HASH_LEN 20
  22 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
  23
  24 #define MIDX_MAX_CHUNKS 5
  25 #define MIDX_CHUNK_ALIGNMENT 4
  26 #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
  27 #define MIDX_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  28 #define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  29 #define MIDX_CHUNKID_OBJECTOFFSETS 0x4f4f4646 /* "OOFF" */
  30 #define MIDX_CHUNKID_LARGEOFFSETS 0x4c4f4646 /* "LOFF" */
  31 #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
  32 #define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
  33 #define MIDX_CHUNK_OFFSET_WIDTH (2 * sizeof(uint32_t))
  34 #define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
  35 #define MIDX_LARGE_OFFSET_NEEDED 0x80000000
  36
  37 static char *get_midx_filename(const char *object_dir)
  38 {
  39         return xstrfmt("%s/pack/multi-pack-index", object_dir);
  40 }
  41
  42 struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local)
  43 {
  44         struct multi_pack_index *m = NULL;
  45         int fd;
  46         struct stat st;
  47         size_t midx_size;
  48         void *midx_map = NULL;
  49         uint32_t hash_version;
  50         char *midx_name = get_midx_filename(object_dir);
  51         uint32_t i;
  52         const char *cur_pack_name;
  53
  54         fd = git_open(midx_name);
  55
  56         if (fd < 0)
  57                 goto cleanup_fail;
  58         if (fstat(fd, &st)) {
  59                 error_errno(_("failed to read %s"), midx_name);
  60                 goto cleanup_fail;
  61         }
  62
  63         midx_size = xsize_t(st.st_size);
  64
  65         if (midx_size < MIDX_MIN_SIZE) {
  66                 error(_("multi-pack-index file %s is too small"), midx_name);
  67                 goto cleanup_fail;
  68         }
  69
  70         FREE_AND_NULL(midx_name);
  71
  72         midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
  73
  74         FLEX_ALLOC_STR(m, object_dir, object_dir);
  75         m->fd = fd;
  76         m->data = midx_map;
  77         m->data_len = midx_size;
  78         m->local = local;
  79
  80         m->signature = get_be32(m->data);
  81         if (m->signature != MIDX_SIGNATURE)
  82                 die(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
  83                       m->signature, MIDX_SIGNATURE);
  84
  85         m->version = m->data[MIDX_BYTE_FILE_VERSION];
  86         if (m->version != MIDX_VERSION)
  87                 die(_("multi-pack-index version %d not recognized"),
  88                       m->version);
  89
  90         hash_version = m->data[MIDX_BYTE_HASH_VERSION];
  91         if (hash_version != MIDX_HASH_VERSION)
  92                 die(_("hash version %u does not match"), hash_version);
  93         m->hash_len = MIDX_HASH_LEN;
  94
  95         m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
  96
  97         m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
  98
  99         for (i = 0; i < m->num_chunks; i++) {
 100                 uint32_t chunk_id = get_be32(m->data + MIDX_HEADER_SIZE +
 101                                              MIDX_CHUNKLOOKUP_WIDTH * i);
 102                 uint64_t chunk_offset = get_be64(m->data + MIDX_HEADER_SIZE + 4 +
 103                                                  MIDX_CHUNKLOOKUP_WIDTH * i);
 104
 105                 if (chunk_offset >= m->data_len)
 106                         die(_("invalid chunk offset (too large)"));
 107
 108                 switch (chunk_id) {
 109                         case MIDX_CHUNKID_PACKNAMES:
 110                                 m->chunk_pack_names = m->data + chunk_offset;
 111                                 break;
 112
 113                         case MIDX_CHUNKID_OIDFANOUT:
 114                                 m->chunk_oid_fanout = (uint32_t *)(m->data + chunk_offset);
 115                                 break;
 116
 117                         case MIDX_CHUNKID_OIDLOOKUP:
 118                                 m->chunk_oid_lookup = m->data + chunk_offset;
 119                                 break;
 120
 121                         case MIDX_CHUNKID_OBJECTOFFSETS:
 122                                 m->chunk_object_offsets = m->data + chunk_offset;
 123                                 break;
 124
 125                         case MIDX_CHUNKID_LARGEOFFSETS:
 126                                 m->chunk_large_offsets = m->data + chunk_offset;
 127                                 break;
 128
 129                         case 0:
 130                                 die(_("terminating multi-pack-index chunk id appears earlier than expected"));
 131                                 break;
 132
 133                         default:
 134                                 /*
 135                                  * Do nothing on unrecognized chunks, allowing future
 136                                  * extensions to add optional chunks.
 137                                  */
 138                                 break;
 139                 }
 140         }
 141
 142         if (!m->chunk_pack_names)
 143                 die(_("multi-pack-index missing required pack-name chunk"));
 144         if (!m->chunk_oid_fanout)
 145                 die(_("multi-pack-index missing required OID fanout chunk"));
 146         if (!m->chunk_oid_lookup)
 147                 die(_("multi-pack-index missing required OID lookup chunk"));
 148         if (!m->chunk_object_offsets)
 149                 die(_("multi-pack-index missing required object offsets chunk"));
 150
 151         m->num_objects = ntohl(m->chunk_oid_fanout[255]);
 152
 153         m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
 154         m->packs = xcalloc(m->num_packs, sizeof(*m->packs));
 155
 156         cur_pack_name = (const char *)m->chunk_pack_names;
 157         for (i = 0; i < m->num_packs; i++) {
 158                 m->pack_names[i] = cur_pack_name;
 159
 160                 cur_pack_name += strlen(cur_pack_name) + 1;
 161
 162                 if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0)
 163                         die(_("multi-pack-index pack names out of order: '%s' before '%s'"),
 164                               m->pack_names[i - 1],
 165                               m->pack_names[i]);
 166         }
 167
 168         trace2_data_intmax("midx", the_repository, "load/num_packs", m->num_packs);
 169         trace2_data_intmax("midx", the_repository, "load/num_objects", m->num_objects);
 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                         m->packs[i]->multi_pack_index = 0;
 197         }
 198         FREE_AND_NULL(m->packs);
 199         FREE_AND_NULL(m->pack_names);
 200 }
 201
 202 int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id)
 203 {
 204         struct strbuf pack_name = STRBUF_INIT;
 205         struct packed_git *p;
 206
 207         if (pack_int_id >= m->num_packs)
 208                 die(_("bad pack-int-id: %u (%u total packs)"),
 209                     pack_int_id, m->num_packs);
 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         p = add_packed_git(pack_name.buf, pack_name.len, m->local);
 218         strbuf_release(&pack_name);
 219
 220         if (!p)
 221                 return 1;
 222
 223         p->multi_pack_index = 1;
 224         m->packs[pack_int_id] = p;
 225         install_packed_git(r, p);
 226         list_add_tail(&p->mru, &r->objects->packed_git_mru);
 227
 228         return 0;
 229 }
 230
 231 int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
 232 {
 233         return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
 234                             MIDX_HASH_LEN, result);
 235 }
 236
 237 struct object_id *nth_midxed_object_oid(struct object_id *oid,
 238                                         struct multi_pack_index *m,
 239                                         uint32_t n)
 240 {
 241         if (n >= m->num_objects)
 242                 return NULL;
 243
 244         hashcpy(oid->hash, m->chunk_oid_lookup + m->hash_len * n);
 245         return oid;
 246 }
 247
 248 static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
 249 {
 250         const unsigned char *offset_data;
 251         uint32_t offset32;
 252
 253         offset_data = m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH;
 254         offset32 = get_be32(offset_data + sizeof(uint32_t));
 255
 256         if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
 257                 if (sizeof(off_t) < sizeof(uint64_t))
 258                         die(_("multi-pack-index stores a 64-bit offset, but off_t is too small"));
 259
 260                 offset32 ^= MIDX_LARGE_OFFSET_NEEDED;
 261                 return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32);
 262         }
 263
 264         return offset32;
 265 }
 266
 267 static uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
 268 {
 269         return get_be32(m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH);
 270 }
 271
 272 static int nth_midxed_pack_entry(struct repository *r,
 273                                  struct multi_pack_index *m,
 274                                  struct pack_entry *e,
 275                                  uint32_t pos)
 276 {
 277         uint32_t pack_int_id;
 278         struct packed_git *p;
 279
 280         if (pos >= m->num_objects)
 281                 return 0;
 282
 283         pack_int_id = nth_midxed_pack_int_id(m, pos);
 284
 285         if (prepare_midx_pack(r, m, pack_int_id))
 286                 die(_("error preparing packfile from multi-pack-index"));
 287         p = m->packs[pack_int_id];
 288
 289         /*
 290         * We are about to tell the caller where they can locate the
 291         * requested object.  We better make sure the packfile is
 292         * still here and can be accessed before supplying that
 293         * answer, as it may have been deleted since the MIDX was
 294         * loaded!
 295         */
 296         if (!is_pack_valid(p))
 297                 return 0;
 298
 299         if (p->num_bad_objects) {
 300                 uint32_t i;
 301                 struct object_id oid;
 302                 nth_midxed_object_oid(&oid, m, pos);
 303                 for (i = 0; i < p->num_bad_objects; i++)
 304                         if (hasheq(oid.hash,
 305                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
 306                                 return 0;
 307         }
 308
 309         e->offset = nth_midxed_offset(m, pos);
 310         e->p = p;
 311
 312         return 1;
 313 }
 314
 315 int fill_midx_entry(struct repository * r,
 316                     const struct object_id *oid,
 317                     struct pack_entry *e,
 318                     struct multi_pack_index *m)
 319 {
 320         uint32_t pos;
 321
 322         if (!bsearch_midx(oid, m, &pos))
 323                 return 0;
 324
 325         return nth_midxed_pack_entry(r, m, e, pos);
 326 }
 327
 328 /* Match "foo.idx" against either "foo.pack" _or_ "foo.idx". */
 329 static int cmp_idx_or_pack_name(const char *idx_or_pack_name,
 330                                 const char *idx_name)
 331 {
 332         /* Skip past any initial matching prefix. */
 333         while (*idx_name && *idx_name == *idx_or_pack_name) {
 334                 idx_name++;
 335                 idx_or_pack_name++;
 336         }
 337
 338         /*
 339          * If we didn't match completely, we may have matched "pack-1234." and
 340          * be left with "idx" and "pack" respectively, which is also OK. We do
 341          * not have to check for "idx" and "idx", because that would have been
 342          * a complete match (and in that case these strcmps will be false, but
 343          * we'll correctly return 0 from the final strcmp() below.
 344          *
 345          * Technically this matches "fooidx" and "foopack", but we'd never have
 346          * such names in the first place.
 347          */
 348         if (!strcmp(idx_name, "idx") && !strcmp(idx_or_pack_name, "pack"))
 349                 return 0;
 350
 351         /*
 352          * This not only checks for a complete match, but also orders based on
 353          * the first non-identical character, which means our ordering will
 354          * match a raw strcmp(). That makes it OK to use this to binary search
 355          * a naively-sorted list.
 356          */
 357         return strcmp(idx_or_pack_name, idx_name);
 358 }
 359
 360 int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
 361 {
 362         uint32_t first = 0, last = m->num_packs;
 363
 364         while (first < last) {
 365                 uint32_t mid = first + (last - first) / 2;
 366                 const char *current;
 367                 int cmp;
 368
 369                 current = m->pack_names[mid];
 370                 cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
 371                 if (!cmp)
 372                         return 1;
 373                 if (cmp > 0) {
 374                         first = mid + 1;
 375                         continue;
 376                 }
 377                 last = mid;
 378         }
 379
 380         return 0;
 381 }
 382
 383 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local)
 384 {
 385         struct multi_pack_index *m;
 386         struct multi_pack_index *m_search;
 387         int config_value;
 388         static int env_value = -1;
 389
 390         if (env_value < 0)
 391                 env_value = git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0);
 392
 393         if (!env_value &&
 394             (repo_config_get_bool(r, "core.multipackindex", &config_value) ||
 395             !config_value))
 396                 return 0;
 397
 398         for (m_search = r->objects->multi_pack_index; m_search; m_search = m_search->next)
 399                 if (!strcmp(object_dir, m_search->object_dir))
 400                         return 1;
 401
 402         m = load_multi_pack_index(object_dir, local);
 403
 404         if (m) {
 405                 m->next = r->objects->multi_pack_index;
 406                 r->objects->multi_pack_index = m;
 407                 return 1;
 408         }
 409
 410         return 0;
 411 }
 412
 413 static size_t write_midx_header(struct hashfile *f,
 414                                 unsigned char num_chunks,
 415                                 uint32_t num_packs)
 416 {
 417         unsigned char byte_values[4];
 418
 419         hashwrite_be32(f, MIDX_SIGNATURE);
 420         byte_values[0] = MIDX_VERSION;
 421         byte_values[1] = MIDX_HASH_VERSION;
 422         byte_values[2] = num_chunks;
 423         byte_values[3] = 0; /* unused */
 424         hashwrite(f, byte_values, sizeof(byte_values));
 425         hashwrite_be32(f, num_packs);
 426
 427         return MIDX_HEADER_SIZE;
 428 }
 429
 430 struct pack_list {
 431         struct packed_git **list;
 432         char **names;
 433         uint32_t nr;
 434         uint32_t alloc_list;
 435         uint32_t alloc_names;
 436         size_t pack_name_concat_len;
 437         struct multi_pack_index *m;
 438 };
 439
 440 static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 441                              const char *file_name, void *data)
 442 {
 443         struct pack_list *packs = (struct pack_list *)data;
 444
 445         if (ends_with(file_name, ".idx")) {
 446                 if (packs->m && midx_contains_pack(packs->m, file_name))
 447                         return;
 448
 449                 ALLOC_GROW(packs->list, packs->nr + 1, packs->alloc_list);
 450                 ALLOC_GROW(packs->names, packs->nr + 1, packs->alloc_names);
 451
 452                 packs->list[packs->nr] = add_packed_git(full_path,
 453                                                         full_path_len,
 454                                                         0);
 455
 456                 if (!packs->list[packs->nr]) {
 457                         warning(_("failed to add packfile '%s'"),
 458                                 full_path);
 459                         return;
 460                 }
 461
 462                 if (open_pack_index(packs->list[packs->nr])) {
 463                         warning(_("failed to open pack-index '%s'"),
 464                                 full_path);
 465                         close_pack(packs->list[packs->nr]);
 466                         FREE_AND_NULL(packs->list[packs->nr]);
 467                         return;
 468                 }
 469
 470                 packs->names[packs->nr] = xstrdup(file_name);
 471                 packs->pack_name_concat_len += strlen(file_name) + 1;
 472                 packs->nr++;
 473         }
 474 }
 475
 476 struct pack_pair {
 477         uint32_t pack_int_id;
 478         char *pack_name;
 479 };
 480
 481 static int pack_pair_compare(const void *_a, const void *_b)
 482 {
 483         struct pack_pair *a = (struct pack_pair *)_a;
 484         struct pack_pair *b = (struct pack_pair *)_b;
 485         return strcmp(a->pack_name, b->pack_name);
 486 }
 487
 488 static void sort_packs_by_name(char **pack_names, uint32_t nr_packs, uint32_t *perm)
 489 {
 490         uint32_t i;
 491         struct pack_pair *pairs;
 492
 493         ALLOC_ARRAY(pairs, nr_packs);
 494
 495         for (i = 0; i < nr_packs; i++) {
 496                 pairs[i].pack_int_id = i;
 497                 pairs[i].pack_name = pack_names[i];
 498         }
 499
 500         QSORT(pairs, nr_packs, pack_pair_compare);
 501
 502         for (i = 0; i < nr_packs; i++) {
 503                 pack_names[i] = pairs[i].pack_name;
 504                 perm[pairs[i].pack_int_id] = i;
 505         }
 506
 507         free(pairs);
 508 }
 509
 510 struct pack_midx_entry {
 511         struct object_id oid;
 512         uint32_t pack_int_id;
 513         time_t pack_mtime;
 514         uint64_t offset;
 515 };
 516
 517 static int midx_oid_compare(const void *_a, const void *_b)
 518 {
 519         const struct pack_midx_entry *a = (const struct pack_midx_entry *)_a;
 520         const struct pack_midx_entry *b = (const struct pack_midx_entry *)_b;
 521         int cmp = oidcmp(&a->oid, &b->oid);
 522
 523         if (cmp)
 524                 return cmp;
 525
 526         if (a->pack_mtime > b->pack_mtime)
 527                 return -1;
 528         else if (a->pack_mtime < b->pack_mtime)
 529                 return 1;
 530
 531         return a->pack_int_id - b->pack_int_id;
 532 }
 533
 534 static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
 535                                       uint32_t *pack_perm,
 536                                       struct pack_midx_entry *e,
 537                                       uint32_t pos)
 538 {
 539         if (pos >= m->num_objects)
 540                 return 1;
 541
 542         nth_midxed_object_oid(&e->oid, m, pos);
 543         e->pack_int_id = pack_perm[nth_midxed_pack_int_id(m, pos)];
 544         e->offset = nth_midxed_offset(m, pos);
 545
 546         /* consider objects in midx to be from "old" packs */
 547         e->pack_mtime = 0;
 548         return 0;
 549 }
 550
 551 static void fill_pack_entry(uint32_t pack_int_id,
 552                             struct packed_git *p,
 553                             uint32_t cur_object,
 554                             struct pack_midx_entry *entry)
 555 {
 556         if (!nth_packed_object_oid(&entry->oid, p, cur_object))
 557                 die(_("failed to locate object %d in packfile"), cur_object);
 558
 559         entry->pack_int_id = pack_int_id;
 560         entry->pack_mtime = p->mtime;
 561
 562         entry->offset = nth_packed_object_offset(p, cur_object);
 563 }
 564
 565 /*
 566  * It is possible to artificially get into a state where there are many
 567  * duplicate copies of objects. That can create high memory pressure if
 568  * we are to create a list of all objects before de-duplication. To reduce
 569  * this memory pressure without a significant performance drop, automatically
 570  * group objects by the first byte of their object id. Use the IDX fanout
 571  * tables to group the data, copy to a local array, then sort.
 572  *
 573  * Copy only the de-duplicated entries (selected by most-recent modified time
 574  * of a packfile containing the object).
 575  */
 576 static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 577                                                   struct packed_git **p,
 578                                                   uint32_t *perm,
 579                                                   uint32_t nr_packs,
 580                                                   uint32_t *nr_objects)
 581 {
 582         uint32_t cur_fanout, cur_pack, cur_object;
 583         uint32_t alloc_fanout, alloc_objects, total_objects = 0;
 584         struct pack_midx_entry *entries_by_fanout = NULL;
 585         struct pack_midx_entry *deduplicated_entries = NULL;
 586         uint32_t start_pack = m ? m->num_packs : 0;
 587
 588         for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
 589                 total_objects += p[cur_pack]->num_objects;
 590
 591         /*
 592          * As we de-duplicate by fanout value, we expect the fanout
 593          * slices to be evenly distributed, with some noise. Hence,
 594          * allocate slightly more than one 256th.
 595          */
 596         alloc_objects = alloc_fanout = total_objects > 3200 ? total_objects / 200 : 16;
 597
 598         ALLOC_ARRAY(entries_by_fanout, alloc_fanout);
 599         ALLOC_ARRAY(deduplicated_entries, alloc_objects);
 600         *nr_objects = 0;
 601
 602         for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
 603                 uint32_t nr_fanout = 0;
 604
 605                 if (m) {
 606                         uint32_t start = 0, end;
 607
 608                         if (cur_fanout)
 609                                 start = ntohl(m->chunk_oid_fanout[cur_fanout - 1]);
 610                         end = ntohl(m->chunk_oid_fanout[cur_fanout]);
 611
 612                         for (cur_object = start; cur_object < end; cur_object++) {
 613                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 614                                 nth_midxed_pack_midx_entry(m, perm,
 615                                                            &entries_by_fanout[nr_fanout],
 616                                                            cur_object);
 617                                 nr_fanout++;
 618                         }
 619                 }
 620
 621                 for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++) {
 622                         uint32_t start = 0, end;
 623
 624                         if (cur_fanout)
 625                                 start = get_pack_fanout(p[cur_pack], cur_fanout - 1);
 626                         end = get_pack_fanout(p[cur_pack], cur_fanout);
 627
 628                         for (cur_object = start; cur_object < end; cur_object++) {
 629                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 630                                 fill_pack_entry(perm[cur_pack], p[cur_pack], cur_object, &entries_by_fanout[nr_fanout]);
 631                                 nr_fanout++;
 632                         }
 633                 }
 634
 635                 QSORT(entries_by_fanout, nr_fanout, midx_oid_compare);
 636
 637                 /*
 638                  * The batch is now sorted by OID and then mtime (descending).
 639                  * Take only the first duplicate.
 640                  */
 641                 for (cur_object = 0; cur_object < nr_fanout; cur_object++) {
 642                         if (cur_object && oideq(&entries_by_fanout[cur_object - 1].oid,
 643                                                 &entries_by_fanout[cur_object].oid))
 644                                 continue;
 645
 646                         ALLOC_GROW(deduplicated_entries, *nr_objects + 1, alloc_objects);
 647                         memcpy(&deduplicated_entries[*nr_objects],
 648                                &entries_by_fanout[cur_object],
 649                                sizeof(struct pack_midx_entry));
 650                         (*nr_objects)++;
 651                 }
 652         }
 653
 654         free(entries_by_fanout);
 655         return deduplicated_entries;
 656 }
 657
 658 static size_t write_midx_pack_names(struct hashfile *f,
 659                                     char **pack_names,
 660                                     uint32_t num_packs)
 661 {
 662         uint32_t i;
 663         unsigned char padding[MIDX_CHUNK_ALIGNMENT];
 664         size_t written = 0;
 665
 666         for (i = 0; i < num_packs; i++) {
 667                 size_t writelen = strlen(pack_names[i]) + 1;
 668
 669                 if (i && strcmp(pack_names[i], pack_names[i - 1]) <= 0)
 670                         BUG("incorrect pack-file order: %s before %s",
 671                             pack_names[i - 1],
 672                             pack_names[i]);
 673
 674                 hashwrite(f, pack_names[i], writelen);
 675                 written += writelen;
 676         }
 677
 678         /* add padding to be aligned */
 679         i = MIDX_CHUNK_ALIGNMENT - (written % MIDX_CHUNK_ALIGNMENT);
 680         if (i < MIDX_CHUNK_ALIGNMENT) {
 681                 memset(padding, 0, sizeof(padding));
 682                 hashwrite(f, padding, i);
 683                 written += i;
 684         }
 685
 686         return written;
 687 }
 688
 689 static size_t write_midx_oid_fanout(struct hashfile *f,
 690                                     struct pack_midx_entry *objects,
 691                                     uint32_t nr_objects)
 692 {
 693         struct pack_midx_entry *list = objects;
 694         struct pack_midx_entry *last = objects + nr_objects;
 695         uint32_t count = 0;
 696         uint32_t i;
 697
 698         /*
 699         * Write the first-level table (the list is sorted,
 700         * but we use a 256-entry lookup to be able to avoid
 701         * having to do eight extra binary search iterations).
 702         */
 703         for (i = 0; i < 256; i++) {
 704                 struct pack_midx_entry *next = list;
 705
 706                 while (next < last && next->oid.hash[0] == i) {
 707                         count++;
 708                         next++;
 709                 }
 710
 711                 hashwrite_be32(f, count);
 712                 list = next;
 713         }
 714
 715         return MIDX_CHUNK_FANOUT_SIZE;
 716 }
 717
 718 static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
 719                                     struct pack_midx_entry *objects,
 720                                     uint32_t nr_objects)
 721 {
 722         struct pack_midx_entry *list = objects;
 723         uint32_t i;
 724         size_t written = 0;
 725
 726         for (i = 0; i < nr_objects; i++) {
 727                 struct pack_midx_entry *obj = list++;
 728
 729                 if (i < nr_objects - 1) {
 730                         struct pack_midx_entry *next = list;
 731                         if (oidcmp(&obj->oid, &next->oid) >= 0)
 732                                 BUG("OIDs not in order: %s >= %s",
 733                                     oid_to_hex(&obj->oid),
 734                                     oid_to_hex(&next->oid));
 735                 }
 736
 737                 hashwrite(f, obj->oid.hash, (int)hash_len);
 738                 written += hash_len;
 739         }
 740
 741         return written;
 742 }
 743
 744 static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
 745                                         struct pack_midx_entry *objects, uint32_t nr_objects)
 746 {
 747         struct pack_midx_entry *list = objects;
 748         uint32_t i, nr_large_offset = 0;
 749         size_t written = 0;
 750
 751         for (i = 0; i < nr_objects; i++) {
 752                 struct pack_midx_entry *obj = list++;
 753
 754                 hashwrite_be32(f, obj->pack_int_id);
 755
 756                 if (large_offset_needed && obj->offset >> 31)
 757                         hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
 758                 else if (!large_offset_needed && obj->offset >> 32)
 759                         BUG("object %s requires a large offset (%"PRIx64") but the MIDX is not writing large offsets!",
 760                             oid_to_hex(&obj->oid),
 761                             obj->offset);
 762                 else
 763                         hashwrite_be32(f, (uint32_t)obj->offset);
 764
 765                 written += MIDX_CHUNK_OFFSET_WIDTH;
 766         }
 767
 768         return written;
 769 }
 770
 771 static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_offset,
 772                                        struct pack_midx_entry *objects, uint32_t nr_objects)
 773 {
 774         struct pack_midx_entry *list = objects, *end = objects + nr_objects;
 775         size_t written = 0;
 776
 777         while (nr_large_offset) {
 778                 struct pack_midx_entry *obj;
 779                 uint64_t offset;
 780
 781                 if (list >= end)
 782                         BUG("too many large-offset objects");
 783
 784                 obj = list++;
 785                 offset = obj->offset;
 786
 787                 if (!(offset >> 31))
 788                         continue;
 789
 790                 hashwrite_be32(f, offset >> 32);
 791                 hashwrite_be32(f, offset & 0xffffffffUL);
 792                 written += 2 * sizeof(uint32_t);
 793
 794                 nr_large_offset--;
 795         }
 796
 797         return written;
 798 }
 799
 800 int write_midx_file(const char *object_dir)
 801 {
 802         unsigned char cur_chunk, num_chunks = 0;
 803         char *midx_name;
 804         uint32_t i;
 805         struct hashfile *f = NULL;
 806         struct lock_file lk;
 807         struct pack_list packs;
 808         uint32_t *pack_perm = NULL;
 809         uint64_t written = 0;
 810         uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
 811         uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
 812         uint32_t nr_entries, num_large_offsets = 0;
 813         struct pack_midx_entry *entries = NULL;
 814         int large_offsets_needed = 0;
 815
 816         midx_name = get_midx_filename(object_dir);
 817         if (safe_create_leading_directories(midx_name)) {
 818                 UNLEAK(midx_name);
 819                 die_errno(_("unable to create leading directories of %s"),
 820                           midx_name);
 821         }
 822
 823         packs.m = load_multi_pack_index(object_dir, 1);
 824
 825         packs.nr = 0;
 826         packs.alloc_list = packs.m ? packs.m->num_packs : 16;
 827         packs.alloc_names = packs.alloc_list;
 828         packs.list = NULL;
 829         packs.names = NULL;
 830         packs.pack_name_concat_len = 0;
 831         ALLOC_ARRAY(packs.list, packs.alloc_list);
 832         ALLOC_ARRAY(packs.names, packs.alloc_names);
 833
 834         if (packs.m) {
 835                 for (i = 0; i < packs.m->num_packs; i++) {
 836                         ALLOC_GROW(packs.list, packs.nr + 1, packs.alloc_list);
 837                         ALLOC_GROW(packs.names, packs.nr + 1, packs.alloc_names);
 838
 839                         packs.list[packs.nr] = NULL;
 840                         packs.names[packs.nr] = xstrdup(packs.m->pack_names[i]);
 841                         packs.pack_name_concat_len += strlen(packs.names[packs.nr]) + 1;
 842                         packs.nr++;
 843                 }
 844         }
 845
 846         for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 847
 848         if (packs.m && packs.nr == packs.m->num_packs)
 849                 goto cleanup;
 850
 851         if (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 852                 packs.pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
 853                                               (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
 854
 855         ALLOC_ARRAY(pack_perm, packs.nr);
 856         sort_packs_by_name(packs.names, packs.nr, pack_perm);
 857
 858         entries = get_sorted_entries(packs.m, packs.list, pack_perm, packs.nr, &nr_entries);
 859
 860         for (i = 0; i < nr_entries; i++) {
 861                 if (entries[i].offset > 0x7fffffff)
 862                         num_large_offsets++;
 863                 if (entries[i].offset > 0xffffffff)
 864                         large_offsets_needed = 1;
 865         }
 866
 867         hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
 868         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 869         FREE_AND_NULL(midx_name);
 870
 871         if (packs.m)
 872                 close_midx(packs.m);
 873
 874         cur_chunk = 0;
 875         num_chunks = large_offsets_needed ? 5 : 4;
 876
 877         written = write_midx_header(f, num_chunks, packs.nr);
 878
 879         chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
 880         chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
 881
 882         cur_chunk++;
 883         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
 884         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
 885
 886         cur_chunk++;
 887         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
 888         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
 889
 890         cur_chunk++;
 891         chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
 892         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
 893
 894         cur_chunk++;
 895         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
 896         if (large_offsets_needed) {
 897                 chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
 898
 899                 cur_chunk++;
 900                 chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
 901                                            num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
 902         }
 903
 904         chunk_ids[cur_chunk] = 0;
 905
 906         for (i = 0; i <= num_chunks; i++) {
 907                 if (i && chunk_offsets[i] < chunk_offsets[i - 1])
 908                         BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
 909                             chunk_offsets[i - 1],
 910                             chunk_offsets[i]);
 911
 912                 if (chunk_offsets[i] % MIDX_CHUNK_ALIGNMENT)
 913                         BUG("chunk offset %"PRIu64" is not properly aligned",
 914                             chunk_offsets[i]);
 915
 916                 hashwrite_be32(f, chunk_ids[i]);
 917                 hashwrite_be32(f, chunk_offsets[i] >> 32);
 918                 hashwrite_be32(f, chunk_offsets[i]);
 919
 920                 written += MIDX_CHUNKLOOKUP_WIDTH;
 921         }
 922
 923         for (i = 0; i < num_chunks; i++) {
 924                 if (written != chunk_offsets[i])
 925                         BUG("incorrect chunk offset (%"PRIu64" != %"PRIu64") for chunk id %"PRIx32,
 926                             chunk_offsets[i],
 927                             written,
 928                             chunk_ids[i]);
 929
 930                 switch (chunk_ids[i]) {
 931                         case MIDX_CHUNKID_PACKNAMES:
 932                                 written += write_midx_pack_names(f, packs.names, packs.nr);
 933                                 break;
 934
 935                         case MIDX_CHUNKID_OIDFANOUT:
 936                                 written += write_midx_oid_fanout(f, entries, nr_entries);
 937                                 break;
 938
 939                         case MIDX_CHUNKID_OIDLOOKUP:
 940                                 written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
 941                                 break;
 942
 943                         case MIDX_CHUNKID_OBJECTOFFSETS:
 944                                 written += write_midx_object_offsets(f, large_offsets_needed, entries, nr_entries);
 945                                 break;
 946
 947                         case MIDX_CHUNKID_LARGEOFFSETS:
 948                                 written += write_midx_large_offsets(f, num_large_offsets, entries, nr_entries);
 949                                 break;
 950
 951                         default:
 952                                 BUG("trying to write unknown chunk id %"PRIx32,
 953                                     chunk_ids[i]);
 954                 }
 955         }
 956
 957         if (written != chunk_offsets[num_chunks])
 958                 BUG("incorrect final offset %"PRIu64" != %"PRIu64,
 959                     written,
 960                     chunk_offsets[num_chunks]);
 961
 962         finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
 963         commit_lock_file(&lk);
 964
 965 cleanup:
 966         for (i = 0; i < packs.nr; i++) {
 967                 if (packs.list[i]) {
 968                         close_pack(packs.list[i]);
 969                         free(packs.list[i]);
 970                 }
 971                 free(packs.names[i]);
 972         }
 973
 974         free(packs.list);
 975         free(packs.names);
 976         free(entries);
 977         free(pack_perm);
 978         free(midx_name);
 979         return 0;
 980 }
 981
 982 void clear_midx_file(struct repository *r)
 983 {
 984         char *midx = get_midx_filename(r->objects->odb->path);
 985
 986         if (r->objects && r->objects->multi_pack_index) {
 987                 close_midx(r->objects->multi_pack_index);
 988                 r->objects->multi_pack_index = NULL;
 989         }
 990
 991         if (remove_path(midx)) {
 992                 UNLEAK(midx);
 993                 die(_("failed to clear multi-pack-index at %s"), midx);
 994         }
 995
 996         free(midx);
 997 }
 998
 999 static int verify_midx_error;
1000
1001 static void midx_report(const char *fmt, ...)
1002 {
1003         va_list ap;
1004         verify_midx_error = 1;
1005         va_start(ap, fmt);
1006         vfprintf(stderr, fmt, ap);
1007         fprintf(stderr, "\n");
1008         va_end(ap);
1009 }
1010
1011 struct pair_pos_vs_id
1012 {
1013         uint32_t pos;
1014         uint32_t pack_int_id;
1015 };
1016
1017 static int compare_pair_pos_vs_id(const void *_a, const void *_b)
1018 {
1019         struct pair_pos_vs_id *a = (struct pair_pos_vs_id *)_a;
1020         struct pair_pos_vs_id *b = (struct pair_pos_vs_id *)_b;
1021
1022         return b->pack_int_id - a->pack_int_id;
1023 }
1024
1025 /*
1026  * Limit calls to display_progress() for performance reasons.
1027  * The interval here was arbitrarily chosen.
1028  */
1029 #define SPARSE_PROGRESS_INTERVAL (1 << 12)
1030 #define midx_display_sparse_progress(progress, n) \
1031         do { \
1032                 uint64_t _n = (n); \
1033                 if ((_n & (SPARSE_PROGRESS_INTERVAL - 1)) == 0) \
1034                         display_progress(progress, _n); \
1035         } while (0)
1036
1037 int verify_midx_file(struct repository *r, const char *object_dir)
1038 {
1039         struct pair_pos_vs_id *pairs = NULL;
1040         uint32_t i;
1041         struct progress *progress;
1042         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1043         verify_midx_error = 0;
1044
1045         if (!m)
1046                 return 0;
1047
1048         progress = start_progress(_("Looking for referenced packfiles"),
1049                                   m->num_packs);
1050         for (i = 0; i < m->num_packs; i++) {
1051                 if (prepare_midx_pack(r, m, i))
1052                         midx_report("failed to load pack in position %d", i);
1053
1054                 display_progress(progress, i + 1);
1055         }
1056         stop_progress(&progress);
1057
1058         for (i = 0; i < 255; i++) {
1059                 uint32_t oid_fanout1 = ntohl(m->chunk_oid_fanout[i]);
1060                 uint32_t oid_fanout2 = ntohl(m->chunk_oid_fanout[i + 1]);
1061
1062                 if (oid_fanout1 > oid_fanout2)
1063                         midx_report(_("oid fanout out of order: fanout[%d] = %"PRIx32" > %"PRIx32" = fanout[%d]"),
1064                                     i, oid_fanout1, oid_fanout2, i + 1);
1065         }
1066
1067         progress = start_sparse_progress(_("Verifying OID order in MIDX"),
1068                                          m->num_objects - 1);
1069         for (i = 0; i < m->num_objects - 1; i++) {
1070                 struct object_id oid1, oid2;
1071
1072                 nth_midxed_object_oid(&oid1, m, i);
1073                 nth_midxed_object_oid(&oid2, m, i + 1);
1074
1075                 if (oidcmp(&oid1, &oid2) >= 0)
1076                         midx_report(_("oid lookup out of order: oid[%d] = %s >= %s = oid[%d]"),
1077                                     i, oid_to_hex(&oid1), oid_to_hex(&oid2), i + 1);
1078
1079                 midx_display_sparse_progress(progress, i + 1);
1080         }
1081         stop_progress(&progress);
1082
1083         /*
1084          * Create an array mapping each object to its packfile id.  Sort it
1085          * to group the objects by packfile.  Use this permutation to visit
1086          * each of the objects and only require 1 packfile to be open at a
1087          * time.
1088          */
1089         ALLOC_ARRAY(pairs, m->num_objects);
1090         for (i = 0; i < m->num_objects; i++) {
1091                 pairs[i].pos = i;
1092                 pairs[i].pack_int_id = nth_midxed_pack_int_id(m, i);
1093         }
1094
1095         progress = start_sparse_progress(_("Sorting objects by packfile"),
1096                                          m->num_objects);
1097         display_progress(progress, 0); /* TODO: Measure QSORT() progress */
1098         QSORT(pairs, m->num_objects, compare_pair_pos_vs_id);
1099         stop_progress(&progress);
1100
1101         progress = start_sparse_progress(_("Verifying object offsets"), m->num_objects);
1102         for (i = 0; i < m->num_objects; i++) {
1103                 struct object_id oid;
1104                 struct pack_entry e;
1105                 off_t m_offset, p_offset;
1106
1107                 if (i > 0 && pairs[i-1].pack_int_id != pairs[i].pack_int_id &&
1108                     m->packs[pairs[i-1].pack_int_id])
1109                 {
1110                         close_pack_fd(m->packs[pairs[i-1].pack_int_id]);
1111                         close_pack_index(m->packs[pairs[i-1].pack_int_id]);
1112                 }
1113
1114                 nth_midxed_object_oid(&oid, m, pairs[i].pos);
1115
1116                 if (!fill_midx_entry(r, &oid, &e, m)) {
1117                         midx_report(_("failed to load pack entry for oid[%d] = %s"),
1118                                     pairs[i].pos, oid_to_hex(&oid));
1119                         continue;
1120                 }
1121
1122                 if (open_pack_index(e.p)) {
1123                         midx_report(_("failed to load pack-index for packfile %s"),
1124                                     e.p->pack_name);
1125                         break;
1126                 }
1127
1128                 m_offset = e.offset;
1129                 p_offset = find_pack_entry_one(oid.hash, e.p);
1130
1131                 if (m_offset != p_offset)
1132                         midx_report(_("incorrect object offset for oid[%d] = %s: %"PRIx64" != %"PRIx64),
1133                                     pairs[i].pos, oid_to_hex(&oid), m_offset, p_offset);
1134
1135                 midx_display_sparse_progress(progress, i + 1);
1136         }
1137         stop_progress(&progress);
1138
1139         free(pairs);
1140
1141         return verify_midx_error;
1142 }