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                         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                 die(_("bad pack-int-id: %u (%u total packs)"),
 210                     pack_int_id, m->num_packs);
 211
 212         if (m->packs[pack_int_id])
 213                 return 0;
 214
 215         strbuf_addf(&pack_name, "%s/pack/%s", m->object_dir,
 216                     m->pack_names[pack_int_id]);
 217
 218         m->packs[pack_int_id] = add_packed_git(pack_name.buf, pack_name.len, m->local);
 219         strbuf_release(&pack_name);
 220         return !m->packs[pack_int_id];
 221 }
 222
 223 int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
 224 {
 225         return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
 226                             MIDX_HASH_LEN, result);
 227 }
 228
 229 struct object_id *nth_midxed_object_oid(struct object_id *oid,
 230                                         struct multi_pack_index *m,
 231                                         uint32_t n)
 232 {
 233         if (n >= m->num_objects)
 234                 return NULL;
 235
 236         hashcpy(oid->hash, m->chunk_oid_lookup + m->hash_len * n);
 237         return oid;
 238 }
 239
 240 static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
 241 {
 242         const unsigned char *offset_data;
 243         uint32_t offset32;
 244
 245         offset_data = m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH;
 246         offset32 = get_be32(offset_data + sizeof(uint32_t));
 247
 248         if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
 249                 if (sizeof(off_t) < sizeof(uint64_t))
 250                         die(_("multi-pack-index stores a 64-bit offset, but off_t is too small"));
 251
 252                 offset32 ^= MIDX_LARGE_OFFSET_NEEDED;
 253                 return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32);
 254         }
 255
 256         return offset32;
 257 }
 258
 259 static uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
 260 {
 261         return get_be32(m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH);
 262 }
 263
 264 static int nth_midxed_pack_entry(struct multi_pack_index *m, struct pack_entry *e, uint32_t pos)
 265 {
 266         uint32_t pack_int_id;
 267         struct packed_git *p;
 268
 269         if (pos >= m->num_objects)
 270                 return 0;
 271
 272         pack_int_id = nth_midxed_pack_int_id(m, pos);
 273
 274         if (prepare_midx_pack(m, pack_int_id))
 275                 die(_("error preparing packfile from multi-pack-index"));
 276         p = m->packs[pack_int_id];
 277
 278         /*
 279         * We are about to tell the caller where they can locate the
 280         * requested object.  We better make sure the packfile is
 281         * still here and can be accessed before supplying that
 282         * answer, as it may have been deleted since the MIDX was
 283         * loaded!
 284         */
 285         if (!is_pack_valid(p))
 286                 return 0;
 287
 288         if (p->num_bad_objects) {
 289                 uint32_t i;
 290                 struct object_id oid;
 291                 nth_midxed_object_oid(&oid, m, pos);
 292                 for (i = 0; i < p->num_bad_objects; i++)
 293                         if (hasheq(oid.hash,
 294                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
 295                                 return 0;
 296         }
 297
 298         e->offset = nth_midxed_offset(m, pos);
 299         e->p = p;
 300
 301         return 1;
 302 }
 303
 304 int fill_midx_entry(const struct object_id *oid, struct pack_entry *e, struct multi_pack_index *m)
 305 {
 306         uint32_t pos;
 307
 308         if (!bsearch_midx(oid, m, &pos))
 309                 return 0;
 310
 311         return nth_midxed_pack_entry(m, e, pos);
 312 }
 313
 314 /* Match "foo.idx" against either "foo.pack" _or_ "foo.idx". */
 315 static int cmp_idx_or_pack_name(const char *idx_or_pack_name,
 316                                 const char *idx_name)
 317 {
 318         /* Skip past any initial matching prefix. */
 319         while (*idx_name && *idx_name == *idx_or_pack_name) {
 320                 idx_name++;
 321                 idx_or_pack_name++;
 322         }
 323
 324         /*
 325          * If we didn't match completely, we may have matched "pack-1234." and
 326          * be left with "idx" and "pack" respectively, which is also OK. We do
 327          * not have to check for "idx" and "idx", because that would have been
 328          * a complete match (and in that case these strcmps will be false, but
 329          * we'll correctly return 0 from the final strcmp() below.
 330          *
 331          * Technically this matches "fooidx" and "foopack", but we'd never have
 332          * such names in the first place.
 333          */
 334         if (!strcmp(idx_name, "idx") && !strcmp(idx_or_pack_name, "pack"))
 335                 return 0;
 336
 337         /*
 338          * This not only checks for a complete match, but also orders based on
 339          * the first non-identical character, which means our ordering will
 340          * match a raw strcmp(). That makes it OK to use this to binary search
 341          * a naively-sorted list.
 342          */
 343         return strcmp(idx_or_pack_name, idx_name);
 344 }
 345
 346 int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
 347 {
 348         uint32_t first = 0, last = m->num_packs;
 349
 350         while (first < last) {
 351                 uint32_t mid = first + (last - first) / 2;
 352                 const char *current;
 353                 int cmp;
 354
 355                 current = m->pack_names[mid];
 356                 cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
 357                 if (!cmp)
 358                         return 1;
 359                 if (cmp > 0) {
 360                         first = mid + 1;
 361                         continue;
 362                 }
 363                 last = mid;
 364         }
 365
 366         return 0;
 367 }
 368
 369 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local)
 370 {
 371         struct multi_pack_index *m;
 372         struct multi_pack_index *m_search;
 373         int config_value;
 374         static int env_value = -1;
 375
 376         if (env_value < 0)
 377                 env_value = git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0);
 378
 379         if (!env_value &&
 380             (repo_config_get_bool(r, "core.multipackindex", &config_value) ||
 381             !config_value))
 382                 return 0;
 383
 384         for (m_search = r->objects->multi_pack_index; m_search; m_search = m_search->next)
 385                 if (!strcmp(object_dir, m_search->object_dir))
 386                         return 1;
 387
 388         m = load_multi_pack_index(object_dir, local);
 389
 390         if (m) {
 391                 m->next = r->objects->multi_pack_index;
 392                 r->objects->multi_pack_index = m;
 393                 return 1;
 394         }
 395
 396         return 0;
 397 }
 398
 399 static size_t write_midx_header(struct hashfile *f,
 400                                 unsigned char num_chunks,
 401                                 uint32_t num_packs)
 402 {
 403         unsigned char byte_values[4];
 404
 405         hashwrite_be32(f, MIDX_SIGNATURE);
 406         byte_values[0] = MIDX_VERSION;
 407         byte_values[1] = MIDX_HASH_VERSION;
 408         byte_values[2] = num_chunks;
 409         byte_values[3] = 0; /* unused */
 410         hashwrite(f, byte_values, sizeof(byte_values));
 411         hashwrite_be32(f, num_packs);
 412
 413         return MIDX_HEADER_SIZE;
 414 }
 415
 416 struct pack_list {
 417         struct packed_git **list;
 418         char **names;
 419         uint32_t nr;
 420         uint32_t alloc_list;
 421         uint32_t alloc_names;
 422         size_t pack_name_concat_len;
 423         struct multi_pack_index *m;
 424 };
 425
 426 static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 427                              const char *file_name, void *data)
 428 {
 429         struct pack_list *packs = (struct pack_list *)data;
 430
 431         if (ends_with(file_name, ".idx")) {
 432                 if (packs->m && midx_contains_pack(packs->m, file_name))
 433                         return;
 434
 435                 ALLOC_GROW(packs->list, packs->nr + 1, packs->alloc_list);
 436                 ALLOC_GROW(packs->names, packs->nr + 1, packs->alloc_names);
 437
 438                 packs->list[packs->nr] = add_packed_git(full_path,
 439                                                         full_path_len,
 440                                                         0);
 441
 442                 if (!packs->list[packs->nr]) {
 443                         warning(_("failed to add packfile '%s'"),
 444                                 full_path);
 445                         return;
 446                 }
 447
 448                 if (open_pack_index(packs->list[packs->nr])) {
 449                         warning(_("failed to open pack-index '%s'"),
 450                                 full_path);
 451                         close_pack(packs->list[packs->nr]);
 452                         FREE_AND_NULL(packs->list[packs->nr]);
 453                         return;
 454                 }
 455
 456                 packs->names[packs->nr] = xstrdup(file_name);
 457                 packs->pack_name_concat_len += strlen(file_name) + 1;
 458                 packs->nr++;
 459         }
 460 }
 461
 462 struct pack_pair {
 463         uint32_t pack_int_id;
 464         char *pack_name;
 465 };
 466
 467 static int pack_pair_compare(const void *_a, const void *_b)
 468 {
 469         struct pack_pair *a = (struct pack_pair *)_a;
 470         struct pack_pair *b = (struct pack_pair *)_b;
 471         return strcmp(a->pack_name, b->pack_name);
 472 }
 473
 474 static void sort_packs_by_name(char **pack_names, uint32_t nr_packs, uint32_t *perm)
 475 {
 476         uint32_t i;
 477         struct pack_pair *pairs;
 478
 479         ALLOC_ARRAY(pairs, nr_packs);
 480
 481         for (i = 0; i < nr_packs; i++) {
 482                 pairs[i].pack_int_id = i;
 483                 pairs[i].pack_name = pack_names[i];
 484         }
 485
 486         QSORT(pairs, nr_packs, pack_pair_compare);
 487
 488         for (i = 0; i < nr_packs; i++) {
 489                 pack_names[i] = pairs[i].pack_name;
 490                 perm[pairs[i].pack_int_id] = i;
 491         }
 492
 493         free(pairs);
 494 }
 495
 496 struct pack_midx_entry {
 497         struct object_id oid;
 498         uint32_t pack_int_id;
 499         time_t pack_mtime;
 500         uint64_t offset;
 501 };
 502
 503 static int midx_oid_compare(const void *_a, const void *_b)
 504 {
 505         const struct pack_midx_entry *a = (const struct pack_midx_entry *)_a;
 506         const struct pack_midx_entry *b = (const struct pack_midx_entry *)_b;
 507         int cmp = oidcmp(&a->oid, &b->oid);
 508
 509         if (cmp)
 510                 return cmp;
 511
 512         if (a->pack_mtime > b->pack_mtime)
 513                 return -1;
 514         else if (a->pack_mtime < b->pack_mtime)
 515                 return 1;
 516
 517         return a->pack_int_id - b->pack_int_id;
 518 }
 519
 520 static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
 521                                       uint32_t *pack_perm,
 522                                       struct pack_midx_entry *e,
 523                                       uint32_t pos)
 524 {
 525         if (pos >= m->num_objects)
 526                 return 1;
 527
 528         nth_midxed_object_oid(&e->oid, m, pos);
 529         e->pack_int_id = pack_perm[nth_midxed_pack_int_id(m, pos)];
 530         e->offset = nth_midxed_offset(m, pos);
 531
 532         /* consider objects in midx to be from "old" packs */
 533         e->pack_mtime = 0;
 534         return 0;
 535 }
 536
 537 static void fill_pack_entry(uint32_t pack_int_id,
 538                             struct packed_git *p,
 539                             uint32_t cur_object,
 540                             struct pack_midx_entry *entry)
 541 {
 542         if (!nth_packed_object_oid(&entry->oid, p, cur_object))
 543                 die(_("failed to locate object %d in packfile"), cur_object);
 544
 545         entry->pack_int_id = pack_int_id;
 546         entry->pack_mtime = p->mtime;
 547
 548         entry->offset = nth_packed_object_offset(p, cur_object);
 549 }
 550
 551 /*
 552  * It is possible to artificially get into a state where there are many
 553  * duplicate copies of objects. That can create high memory pressure if
 554  * we are to create a list of all objects before de-duplication. To reduce
 555  * this memory pressure without a significant performance drop, automatically
 556  * group objects by the first byte of their object id. Use the IDX fanout
 557  * tables to group the data, copy to a local array, then sort.
 558  *
 559  * Copy only the de-duplicated entries (selected by most-recent modified time
 560  * of a packfile containing the object).
 561  */
 562 static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 563                                                   struct packed_git **p,
 564                                                   uint32_t *perm,
 565                                                   uint32_t nr_packs,
 566                                                   uint32_t *nr_objects)
 567 {
 568         uint32_t cur_fanout, cur_pack, cur_object;
 569         uint32_t alloc_fanout, alloc_objects, total_objects = 0;
 570         struct pack_midx_entry *entries_by_fanout = NULL;
 571         struct pack_midx_entry *deduplicated_entries = NULL;
 572         uint32_t start_pack = m ? m->num_packs : 0;
 573
 574         for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
 575                 total_objects += p[cur_pack]->num_objects;
 576
 577         /*
 578          * As we de-duplicate by fanout value, we expect the fanout
 579          * slices to be evenly distributed, with some noise. Hence,
 580          * allocate slightly more than one 256th.
 581          */
 582         alloc_objects = alloc_fanout = total_objects > 3200 ? total_objects / 200 : 16;
 583
 584         ALLOC_ARRAY(entries_by_fanout, alloc_fanout);
 585         ALLOC_ARRAY(deduplicated_entries, alloc_objects);
 586         *nr_objects = 0;
 587
 588         for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
 589                 uint32_t nr_fanout = 0;
 590
 591                 if (m) {
 592                         uint32_t start = 0, end;
 593
 594                         if (cur_fanout)
 595                                 start = ntohl(m->chunk_oid_fanout[cur_fanout - 1]);
 596                         end = ntohl(m->chunk_oid_fanout[cur_fanout]);
 597
 598                         for (cur_object = start; cur_object < end; cur_object++) {
 599                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 600                                 nth_midxed_pack_midx_entry(m, perm,
 601                                                            &entries_by_fanout[nr_fanout],
 602                                                            cur_object);
 603                                 nr_fanout++;
 604                         }
 605                 }
 606
 607                 for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++) {
 608                         uint32_t start = 0, end;
 609
 610                         if (cur_fanout)
 611                                 start = get_pack_fanout(p[cur_pack], cur_fanout - 1);
 612                         end = get_pack_fanout(p[cur_pack], cur_fanout);
 613
 614                         for (cur_object = start; cur_object < end; cur_object++) {
 615                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 616                                 fill_pack_entry(perm[cur_pack], p[cur_pack], cur_object, &entries_by_fanout[nr_fanout]);
 617                                 nr_fanout++;
 618                         }
 619                 }
 620
 621                 QSORT(entries_by_fanout, nr_fanout, midx_oid_compare);
 622
 623                 /*
 624                  * The batch is now sorted by OID and then mtime (descending).
 625                  * Take only the first duplicate.
 626                  */
 627                 for (cur_object = 0; cur_object < nr_fanout; cur_object++) {
 628                         if (cur_object && oideq(&entries_by_fanout[cur_object - 1].oid,
 629                                                 &entries_by_fanout[cur_object].oid))
 630                                 continue;
 631
 632                         ALLOC_GROW(deduplicated_entries, *nr_objects + 1, alloc_objects);
 633                         memcpy(&deduplicated_entries[*nr_objects],
 634                                &entries_by_fanout[cur_object],
 635                                sizeof(struct pack_midx_entry));
 636                         (*nr_objects)++;
 637                 }
 638         }
 639
 640         free(entries_by_fanout);
 641         return deduplicated_entries;
 642 }
 643
 644 static size_t write_midx_pack_names(struct hashfile *f,
 645                                     char **pack_names,
 646                                     uint32_t num_packs)
 647 {
 648         uint32_t i;
 649         unsigned char padding[MIDX_CHUNK_ALIGNMENT];
 650         size_t written = 0;
 651
 652         for (i = 0; i < num_packs; i++) {
 653                 size_t writelen = strlen(pack_names[i]) + 1;
 654
 655                 if (i && strcmp(pack_names[i], pack_names[i - 1]) <= 0)
 656                         BUG("incorrect pack-file order: %s before %s",
 657                             pack_names[i - 1],
 658                             pack_names[i]);
 659
 660                 hashwrite(f, pack_names[i], writelen);
 661                 written += writelen;
 662         }
 663
 664         /* add padding to be aligned */
 665         i = MIDX_CHUNK_ALIGNMENT - (written % MIDX_CHUNK_ALIGNMENT);
 666         if (i < MIDX_CHUNK_ALIGNMENT) {
 667                 memset(padding, 0, sizeof(padding));
 668                 hashwrite(f, padding, i);
 669                 written += i;
 670         }
 671
 672         return written;
 673 }
 674
 675 static size_t write_midx_oid_fanout(struct hashfile *f,
 676                                     struct pack_midx_entry *objects,
 677                                     uint32_t nr_objects)
 678 {
 679         struct pack_midx_entry *list = objects;
 680         struct pack_midx_entry *last = objects + nr_objects;
 681         uint32_t count = 0;
 682         uint32_t i;
 683
 684         /*
 685         * Write the first-level table (the list is sorted,
 686         * but we use a 256-entry lookup to be able to avoid
 687         * having to do eight extra binary search iterations).
 688         */
 689         for (i = 0; i < 256; i++) {
 690                 struct pack_midx_entry *next = list;
 691
 692                 while (next < last && next->oid.hash[0] == i) {
 693                         count++;
 694                         next++;
 695                 }
 696
 697                 hashwrite_be32(f, count);
 698                 list = next;
 699         }
 700
 701         return MIDX_CHUNK_FANOUT_SIZE;
 702 }
 703
 704 static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
 705                                     struct pack_midx_entry *objects,
 706                                     uint32_t nr_objects)
 707 {
 708         struct pack_midx_entry *list = objects;
 709         uint32_t i;
 710         size_t written = 0;
 711
 712         for (i = 0; i < nr_objects; i++) {
 713                 struct pack_midx_entry *obj = list++;
 714
 715                 if (i < nr_objects - 1) {
 716                         struct pack_midx_entry *next = list;
 717                         if (oidcmp(&obj->oid, &next->oid) >= 0)
 718                                 BUG("OIDs not in order: %s >= %s",
 719                                     oid_to_hex(&obj->oid),
 720                                     oid_to_hex(&next->oid));
 721                 }
 722
 723                 hashwrite(f, obj->oid.hash, (int)hash_len);
 724                 written += hash_len;
 725         }
 726
 727         return written;
 728 }
 729
 730 static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
 731                                         struct pack_midx_entry *objects, uint32_t nr_objects)
 732 {
 733         struct pack_midx_entry *list = objects;
 734         uint32_t i, nr_large_offset = 0;
 735         size_t written = 0;
 736
 737         for (i = 0; i < nr_objects; i++) {
 738                 struct pack_midx_entry *obj = list++;
 739
 740                 hashwrite_be32(f, obj->pack_int_id);
 741
 742                 if (large_offset_needed && obj->offset >> 31)
 743                         hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
 744                 else if (!large_offset_needed && obj->offset >> 32)
 745                         BUG("object %s requires a large offset (%"PRIx64") but the MIDX is not writing large offsets!",
 746                             oid_to_hex(&obj->oid),
 747                             obj->offset);
 748                 else
 749                         hashwrite_be32(f, (uint32_t)obj->offset);
 750
 751                 written += MIDX_CHUNK_OFFSET_WIDTH;
 752         }
 753
 754         return written;
 755 }
 756
 757 static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_offset,
 758                                        struct pack_midx_entry *objects, uint32_t nr_objects)
 759 {
 760         struct pack_midx_entry *list = objects, *end = objects + nr_objects;
 761         size_t written = 0;
 762
 763         while (nr_large_offset) {
 764                 struct pack_midx_entry *obj;
 765                 uint64_t offset;
 766
 767                 if (list >= end)
 768                         BUG("too many large-offset objects");
 769
 770                 obj = list++;
 771                 offset = obj->offset;
 772
 773                 if (!(offset >> 31))
 774                         continue;
 775
 776                 hashwrite_be32(f, offset >> 32);
 777                 hashwrite_be32(f, offset & 0xffffffffUL);
 778                 written += 2 * sizeof(uint32_t);
 779
 780                 nr_large_offset--;
 781         }
 782
 783         return written;
 784 }
 785
 786 int write_midx_file(const char *object_dir)
 787 {
 788         unsigned char cur_chunk, num_chunks = 0;
 789         char *midx_name;
 790         uint32_t i;
 791         struct hashfile *f = NULL;
 792         struct lock_file lk;
 793         struct pack_list packs;
 794         uint32_t *pack_perm = NULL;
 795         uint64_t written = 0;
 796         uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
 797         uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
 798         uint32_t nr_entries, num_large_offsets = 0;
 799         struct pack_midx_entry *entries = NULL;
 800         int large_offsets_needed = 0;
 801
 802         midx_name = get_midx_filename(object_dir);
 803         if (safe_create_leading_directories(midx_name)) {
 804                 UNLEAK(midx_name);
 805                 die_errno(_("unable to create leading directories of %s"),
 806                           midx_name);
 807         }
 808
 809         packs.m = load_multi_pack_index(object_dir, 1);
 810
 811         packs.nr = 0;
 812         packs.alloc_list = packs.m ? packs.m->num_packs : 16;
 813         packs.alloc_names = packs.alloc_list;
 814         packs.list = NULL;
 815         packs.names = NULL;
 816         packs.pack_name_concat_len = 0;
 817         ALLOC_ARRAY(packs.list, packs.alloc_list);
 818         ALLOC_ARRAY(packs.names, packs.alloc_names);
 819
 820         if (packs.m) {
 821                 for (i = 0; i < packs.m->num_packs; i++) {
 822                         ALLOC_GROW(packs.list, packs.nr + 1, packs.alloc_list);
 823                         ALLOC_GROW(packs.names, packs.nr + 1, packs.alloc_names);
 824
 825                         packs.list[packs.nr] = NULL;
 826                         packs.names[packs.nr] = xstrdup(packs.m->pack_names[i]);
 827                         packs.pack_name_concat_len += strlen(packs.names[packs.nr]) + 1;
 828                         packs.nr++;
 829                 }
 830         }
 831
 832         for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 833
 834         if (packs.m && packs.nr == packs.m->num_packs)
 835                 goto cleanup;
 836
 837         if (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 838                 packs.pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
 839                                               (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
 840
 841         ALLOC_ARRAY(pack_perm, packs.nr);
 842         sort_packs_by_name(packs.names, packs.nr, pack_perm);
 843
 844         entries = get_sorted_entries(packs.m, packs.list, pack_perm, packs.nr, &nr_entries);
 845
 846         for (i = 0; i < nr_entries; i++) {
 847                 if (entries[i].offset > 0x7fffffff)
 848                         num_large_offsets++;
 849                 if (entries[i].offset > 0xffffffff)
 850                         large_offsets_needed = 1;
 851         }
 852
 853         hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
 854         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 855         FREE_AND_NULL(midx_name);
 856
 857         if (packs.m)
 858                 close_midx(packs.m);
 859
 860         cur_chunk = 0;
 861         num_chunks = large_offsets_needed ? 5 : 4;
 862
 863         written = write_midx_header(f, num_chunks, packs.nr);
 864
 865         chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
 866         chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
 867
 868         cur_chunk++;
 869         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
 870         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
 871
 872         cur_chunk++;
 873         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
 874         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
 875
 876         cur_chunk++;
 877         chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
 878         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
 879
 880         cur_chunk++;
 881         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
 882         if (large_offsets_needed) {
 883                 chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
 884
 885                 cur_chunk++;
 886                 chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
 887                                            num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
 888         }
 889
 890         chunk_ids[cur_chunk] = 0;
 891
 892         for (i = 0; i <= num_chunks; i++) {
 893                 if (i && chunk_offsets[i] < chunk_offsets[i - 1])
 894                         BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
 895                             chunk_offsets[i - 1],
 896                             chunk_offsets[i]);
 897
 898                 if (chunk_offsets[i] % MIDX_CHUNK_ALIGNMENT)
 899                         BUG("chunk offset %"PRIu64" is not properly aligned",
 900                             chunk_offsets[i]);
 901
 902                 hashwrite_be32(f, chunk_ids[i]);
 903                 hashwrite_be32(f, chunk_offsets[i] >> 32);
 904                 hashwrite_be32(f, chunk_offsets[i]);
 905
 906                 written += MIDX_CHUNKLOOKUP_WIDTH;
 907         }
 908
 909         for (i = 0; i < num_chunks; i++) {
 910                 if (written != chunk_offsets[i])
 911                         BUG("incorrect chunk offset (%"PRIu64" != %"PRIu64") for chunk id %"PRIx32,
 912                             chunk_offsets[i],
 913                             written,
 914                             chunk_ids[i]);
 915
 916                 switch (chunk_ids[i]) {
 917                         case MIDX_CHUNKID_PACKNAMES:
 918                                 written += write_midx_pack_names(f, packs.names, packs.nr);
 919                                 break;
 920
 921                         case MIDX_CHUNKID_OIDFANOUT:
 922                                 written += write_midx_oid_fanout(f, entries, nr_entries);
 923                                 break;
 924
 925                         case MIDX_CHUNKID_OIDLOOKUP:
 926                                 written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
 927                                 break;
 928
 929                         case MIDX_CHUNKID_OBJECTOFFSETS:
 930                                 written += write_midx_object_offsets(f, large_offsets_needed, entries, nr_entries);
 931                                 break;
 932
 933                         case MIDX_CHUNKID_LARGEOFFSETS:
 934                                 written += write_midx_large_offsets(f, num_large_offsets, entries, nr_entries);
 935                                 break;
 936
 937                         default:
 938                                 BUG("trying to write unknown chunk id %"PRIx32,
 939                                     chunk_ids[i]);
 940                 }
 941         }
 942
 943         if (written != chunk_offsets[num_chunks])
 944                 BUG("incorrect final offset %"PRIu64" != %"PRIu64,
 945                     written,
 946                     chunk_offsets[num_chunks]);
 947
 948         finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
 949         commit_lock_file(&lk);
 950
 951 cleanup:
 952         for (i = 0; i < packs.nr; i++) {
 953                 if (packs.list[i]) {
 954                         close_pack(packs.list[i]);
 955                         free(packs.list[i]);
 956                 }
 957                 free(packs.names[i]);
 958         }
 959
 960         free(packs.list);
 961         free(packs.names);
 962         free(entries);
 963         free(pack_perm);
 964         free(midx_name);
 965         return 0;
 966 }
 967
 968 void clear_midx_file(struct repository *r)
 969 {
 970         char *midx = get_midx_filename(r->objects->odb->path);
 971
 972         if (r->objects && r->objects->multi_pack_index) {
 973                 close_midx(r->objects->multi_pack_index);
 974                 r->objects->multi_pack_index = NULL;
 975         }
 976
 977         if (remove_path(midx)) {
 978                 UNLEAK(midx);
 979                 die(_("failed to clear multi-pack-index at %s"), midx);
 980         }
 981
 982         free(midx);
 983 }
 984
 985 static int verify_midx_error;
 986
 987 static void midx_report(const char *fmt, ...)
 988 {
 989         va_list ap;
 990         verify_midx_error = 1;
 991         va_start(ap, fmt);
 992         vfprintf(stderr, fmt, ap);
 993         fprintf(stderr, "\n");
 994         va_end(ap);
 995 }
 996
 997 struct pair_pos_vs_id
 998 {
 999         uint32_t pos;
1000         uint32_t pack_int_id;
1001 };
1002
1003 static int compare_pair_pos_vs_id(const void *_a, const void *_b)
1004 {
1005         struct pair_pos_vs_id *a = (struct pair_pos_vs_id *)_a;
1006         struct pair_pos_vs_id *b = (struct pair_pos_vs_id *)_b;
1007
1008         return b->pack_int_id - a->pack_int_id;
1009 }
1010
1011 /*
1012  * Limit calls to display_progress() for performance reasons.
1013  * The interval here was arbitrarily chosen.
1014  */
1015 #define SPARSE_PROGRESS_INTERVAL (1 << 12)
1016 #define midx_display_sparse_progress(progress, n) \
1017         do { \
1018                 uint64_t _n = (n); \
1019                 if ((_n & (SPARSE_PROGRESS_INTERVAL - 1)) == 0) \
1020                         display_progress(progress, _n); \
1021         } while (0)
1022
1023 int verify_midx_file(const char *object_dir)
1024 {
1025         struct pair_pos_vs_id *pairs = NULL;
1026         uint32_t i;
1027         struct progress *progress;
1028         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1029         verify_midx_error = 0;
1030
1031         if (!m)
1032                 return 0;
1033
1034         progress = start_progress(_("Looking for referenced packfiles"),
1035                                   m->num_packs);
1036         for (i = 0; i < m->num_packs; i++) {
1037                 if (prepare_midx_pack(m, i))
1038                         midx_report("failed to load pack in position %d", i);
1039
1040                 display_progress(progress, i + 1);
1041         }
1042         stop_progress(&progress);
1043
1044         for (i = 0; i < 255; i++) {
1045                 uint32_t oid_fanout1 = ntohl(m->chunk_oid_fanout[i]);
1046                 uint32_t oid_fanout2 = ntohl(m->chunk_oid_fanout[i + 1]);
1047
1048                 if (oid_fanout1 > oid_fanout2)
1049                         midx_report(_("oid fanout out of order: fanout[%d] = %"PRIx32" > %"PRIx32" = fanout[%d]"),
1050                                     i, oid_fanout1, oid_fanout2, i + 1);
1051         }
1052
1053         progress = start_sparse_progress(_("Verifying OID order in MIDX"),
1054                                          m->num_objects - 1);
1055         for (i = 0; i < m->num_objects - 1; i++) {
1056                 struct object_id oid1, oid2;
1057
1058                 nth_midxed_object_oid(&oid1, m, i);
1059                 nth_midxed_object_oid(&oid2, m, i + 1);
1060
1061                 if (oidcmp(&oid1, &oid2) >= 0)
1062                         midx_report(_("oid lookup out of order: oid[%d] = %s >= %s = oid[%d]"),
1063                                     i, oid_to_hex(&oid1), oid_to_hex(&oid2), i + 1);
1064
1065                 midx_display_sparse_progress(progress, i + 1);
1066         }
1067         stop_progress(&progress);
1068
1069         /*
1070          * Create an array mapping each object to its packfile id.  Sort it
1071          * to group the objects by packfile.  Use this permutation to visit
1072          * each of the objects and only require 1 packfile to be open at a
1073          * time.
1074          */
1075         ALLOC_ARRAY(pairs, m->num_objects);
1076         for (i = 0; i < m->num_objects; i++) {
1077                 pairs[i].pos = i;
1078                 pairs[i].pack_int_id = nth_midxed_pack_int_id(m, i);
1079         }
1080
1081         progress = start_sparse_progress(_("Sorting objects by packfile"),
1082                                          m->num_objects);
1083         display_progress(progress, 0); /* TODO: Measure QSORT() progress */
1084         QSORT(pairs, m->num_objects, compare_pair_pos_vs_id);
1085         stop_progress(&progress);
1086
1087         progress = start_sparse_progress(_("Verifying object offsets"), m->num_objects);
1088         for (i = 0; i < m->num_objects; i++) {
1089                 struct object_id oid;
1090                 struct pack_entry e;
1091                 off_t m_offset, p_offset;
1092
1093                 if (i > 0 && pairs[i-1].pack_int_id != pairs[i].pack_int_id &&
1094                     m->packs[pairs[i-1].pack_int_id])
1095                 {
1096                         close_pack_fd(m->packs[pairs[i-1].pack_int_id]);
1097                         close_pack_index(m->packs[pairs[i-1].pack_int_id]);
1098                 }
1099
1100                 nth_midxed_object_oid(&oid, m, pairs[i].pos);
1101
1102                 if (!fill_midx_entry(&oid, &e, m)) {
1103                         midx_report(_("failed to load pack entry for oid[%d] = %s"),
1104                                     pairs[i].pos, oid_to_hex(&oid));
1105                         continue;
1106                 }
1107
1108                 if (open_pack_index(e.p)) {
1109                         midx_report(_("failed to load pack-index for packfile %s"),
1110                                     e.p->pack_name);
1111                         break;
1112                 }
1113
1114                 m_offset = e.offset;
1115                 p_offset = find_pack_entry_one(oid.hash, e.p);
1116
1117                 if (m_offset != p_offset)
1118                         midx_report(_("incorrect object offset for oid[%d] = %s: %"PRIx64" != %"PRIx64),
1119                                     pairs[i].pos, oid_to_hex(&oid), m_offset, p_offset);
1120
1121                 midx_display_sparse_progress(progress, i + 1);
1122         }
1123         stop_progress(&progress);
1124
1125         free(pairs);
1126
1127         return verify_midx_error;
1128 }