git.oblomov.eu Git - git/blob - commit-graph.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "dir.h"
   4 #include "git-compat-util.h"
   5 #include "lockfile.h"
   6 #include "pack.h"
   7 #include "packfile.h"
   8 #include "commit.h"
   9 #include "object.h"
  10 #include "refs.h"
  11 #include "revision.h"
  12 #include "sha1-lookup.h"
  13 #include "commit-graph.h"
  14 #include "object-store.h"
  15 #include "alloc.h"
  16 #include "hashmap.h"
  17 #include "replace-object.h"
  18 #include "progress.h"
  19
  20 #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
  21 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  22 #define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  23 #define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
  24 #define GRAPH_CHUNKID_EXTRAEDGES 0x45444745 /* "EDGE" */
  25
  26 #define GRAPH_DATA_WIDTH (the_hash_algo->rawsz + 16)
  27
  28 #define GRAPH_VERSION_1 0x1
  29 #define GRAPH_VERSION GRAPH_VERSION_1
  30
  31 #define GRAPH_EXTRA_EDGES_NEEDED 0x80000000
  32 #define GRAPH_EDGE_LAST_MASK 0x7fffffff
  33 #define GRAPH_PARENT_NONE 0x70000000
  34
  35 #define GRAPH_LAST_EDGE 0x80000000
  36
  37 #define GRAPH_HEADER_SIZE 8
  38 #define GRAPH_FANOUT_SIZE (4 * 256)
  39 #define GRAPH_CHUNKLOOKUP_WIDTH 12
  40 #define GRAPH_MIN_SIZE (GRAPH_HEADER_SIZE + 4 * GRAPH_CHUNKLOOKUP_WIDTH \
  41                         + GRAPH_FANOUT_SIZE + the_hash_algo->rawsz)
  42
  43 char *get_commit_graph_filename(const char *obj_dir)
  44 {
  45         return xstrfmt("%s/info/commit-graph", obj_dir);
  46 }
  47
  48 static uint8_t oid_version(void)
  49 {
  50         return 1;
  51 }
  52
  53 static struct commit_graph *alloc_commit_graph(void)
  54 {
  55         struct commit_graph *g = xcalloc(1, sizeof(*g));
  56         g->graph_fd = -1;
  57
  58         return g;
  59 }
  60
  61 extern int read_replace_refs;
  62
  63 static int commit_graph_compatible(struct repository *r)
  64 {
  65         if (!r->gitdir)
  66                 return 0;
  67
  68         if (read_replace_refs) {
  69                 prepare_replace_object(r);
  70                 if (hashmap_get_size(&r->objects->replace_map->map))
  71                         return 0;
  72         }
  73
  74         prepare_commit_graft(r);
  75         if (r->parsed_objects && r->parsed_objects->grafts_nr)
  76                 return 0;
  77         if (is_repository_shallow(r))
  78                 return 0;
  79
  80         return 1;
  81 }
  82
  83 struct commit_graph *load_commit_graph_one(const char *graph_file)
  84 {
  85         void *graph_map;
  86         size_t graph_size;
  87         struct stat st;
  88         struct commit_graph *ret;
  89         int fd = git_open(graph_file);
  90
  91         if (fd < 0)
  92                 return NULL;
  93         if (fstat(fd, &st)) {
  94                 close(fd);
  95                 return NULL;
  96         }
  97         graph_size = xsize_t(st.st_size);
  98
  99         if (graph_size < GRAPH_MIN_SIZE) {
 100                 close(fd);
 101                 die(_("graph file %s is too small"), graph_file);
 102         }
 103         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
 104         ret = parse_commit_graph(graph_map, fd, graph_size);
 105
 106         if (!ret) {
 107                 munmap(graph_map, graph_size);
 108                 close(fd);
 109                 exit(1);
 110         }
 111
 112         return ret;
 113 }
 114
 115 static int verify_commit_graph_lite(struct commit_graph *g)
 116 {
 117         /*
 118          * Basic validation shared between parse_commit_graph()
 119          * which'll be called every time the graph is used, and the
 120          * much more expensive verify_commit_graph() used by
 121          * "commit-graph verify".
 122          *
 123          * There should only be very basic checks here to ensure that
 124          * we don't e.g. segfault in fill_commit_in_graph(), but
 125          * because this is a very hot codepath nothing that e.g. loops
 126          * over g->num_commits, or runs a checksum on the commit-graph
 127          * itself.
 128          */
 129         if (!g->chunk_oid_fanout) {
 130                 error("commit-graph is missing the OID Fanout chunk");
 131                 return 1;
 132         }
 133         if (!g->chunk_oid_lookup) {
 134                 error("commit-graph is missing the OID Lookup chunk");
 135                 return 1;
 136         }
 137         if (!g->chunk_commit_data) {
 138                 error("commit-graph is missing the Commit Data chunk");
 139                 return 1;
 140         }
 141
 142         return 0;
 143 }
 144
 145 struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 146                                         size_t graph_size)
 147 {
 148         const unsigned char *data, *chunk_lookup;
 149         uint32_t i;
 150         struct commit_graph *graph;
 151         uint64_t last_chunk_offset;
 152         uint32_t last_chunk_id;
 153         uint32_t graph_signature;
 154         unsigned char graph_version, hash_version;
 155
 156         if (!graph_map)
 157                 return NULL;
 158
 159         if (graph_size < GRAPH_MIN_SIZE)
 160                 return NULL;
 161
 162         data = (const unsigned char *)graph_map;
 163
 164         graph_signature = get_be32(data);
 165         if (graph_signature != GRAPH_SIGNATURE) {
 166                 error(_("graph signature %X does not match signature %X"),
 167                       graph_signature, GRAPH_SIGNATURE);
 168                 return NULL;
 169         }
 170
 171         graph_version = *(unsigned char*)(data + 4);
 172         if (graph_version != GRAPH_VERSION) {
 173                 error(_("graph version %X does not match version %X"),
 174                       graph_version, GRAPH_VERSION);
 175                 return NULL;
 176         }
 177
 178         hash_version = *(unsigned char*)(data + 5);
 179         if (hash_version != oid_version()) {
 180                 error(_("hash version %X does not match version %X"),
 181                       hash_version, oid_version());
 182                 return NULL;
 183         }
 184
 185         graph = alloc_commit_graph();
 186
 187         graph->hash_len = the_hash_algo->rawsz;
 188         graph->num_chunks = *(unsigned char*)(data + 6);
 189         graph->graph_fd = fd;
 190         graph->data = graph_map;
 191         graph->data_len = graph_size;
 192
 193         last_chunk_id = 0;
 194         last_chunk_offset = 8;
 195         chunk_lookup = data + 8;
 196         for (i = 0; i < graph->num_chunks; i++) {
 197                 uint32_t chunk_id;
 198                 uint64_t chunk_offset;
 199                 int chunk_repeated = 0;
 200
 201                 if (data + graph_size - chunk_lookup <
 202                     GRAPH_CHUNKLOOKUP_WIDTH) {
 203                         error(_("chunk lookup table entry missing; graph file may be incomplete"));
 204                         free(graph);
 205                         return NULL;
 206                 }
 207
 208                 chunk_id = get_be32(chunk_lookup + 0);
 209                 chunk_offset = get_be64(chunk_lookup + 4);
 210
 211                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 212
 213                 if (chunk_offset > graph_size - the_hash_algo->rawsz) {
 214                         error(_("improper chunk offset %08x%08x"), (uint32_t)(chunk_offset >> 32),
 215                               (uint32_t)chunk_offset);
 216                         free(graph);
 217                         return NULL;
 218                 }
 219
 220                 switch (chunk_id) {
 221                 case GRAPH_CHUNKID_OIDFANOUT:
 222                         if (graph->chunk_oid_fanout)
 223                                 chunk_repeated = 1;
 224                         else
 225                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 226                         break;
 227
 228                 case GRAPH_CHUNKID_OIDLOOKUP:
 229                         if (graph->chunk_oid_lookup)
 230                                 chunk_repeated = 1;
 231                         else
 232                                 graph->chunk_oid_lookup = data + chunk_offset;
 233                         break;
 234
 235                 case GRAPH_CHUNKID_DATA:
 236                         if (graph->chunk_commit_data)
 237                                 chunk_repeated = 1;
 238                         else
 239                                 graph->chunk_commit_data = data + chunk_offset;
 240                         break;
 241
 242                 case GRAPH_CHUNKID_EXTRAEDGES:
 243                         if (graph->chunk_extra_edges)
 244                                 chunk_repeated = 1;
 245                         else
 246                                 graph->chunk_extra_edges = data + chunk_offset;
 247                         break;
 248                 }
 249
 250                 if (chunk_repeated) {
 251                         error(_("chunk id %08x appears multiple times"), chunk_id);
 252                         free(graph);
 253                         return NULL;
 254                 }
 255
 256                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 257                 {
 258                         graph->num_commits = (chunk_offset - last_chunk_offset)
 259                                              / graph->hash_len;
 260                 }
 261
 262                 last_chunk_id = chunk_id;
 263                 last_chunk_offset = chunk_offset;
 264         }
 265
 266         if (verify_commit_graph_lite(graph))
 267                 return NULL;
 268
 269         return graph;
 270 }
 271
 272 static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
 273 {
 274         char *graph_name;
 275
 276         if (r->objects->commit_graph)
 277                 return;
 278
 279         graph_name = get_commit_graph_filename(obj_dir);
 280         r->objects->commit_graph =
 281                 load_commit_graph_one(graph_name);
 282
 283         FREE_AND_NULL(graph_name);
 284 }
 285
 286 /*
 287  * Return 1 if commit_graph is non-NULL, and 0 otherwise.
 288  *
 289  * On the first invocation, this function attemps to load the commit
 290  * graph if the_repository is configured to have one.
 291  */
 292 static int prepare_commit_graph(struct repository *r)
 293 {
 294         struct object_directory *odb;
 295         int config_value;
 296
 297         if (r->objects->commit_graph_attempted)
 298                 return !!r->objects->commit_graph;
 299         r->objects->commit_graph_attempted = 1;
 300
 301         if (!git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
 302             (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
 303             !config_value))
 304                 /*
 305                  * This repository is not configured to use commit graphs, so
 306                  * do not load one. (But report commit_graph_attempted anyway
 307                  * so that commit graph loading is not attempted again for this
 308                  * repository.)
 309                  */
 310                 return 0;
 311
 312         if (!commit_graph_compatible(r))
 313                 return 0;
 314
 315         prepare_alt_odb(r);
 316         for (odb = r->objects->odb;
 317              !r->objects->commit_graph && odb;
 318              odb = odb->next)
 319                 prepare_commit_graph_one(r, odb->path);
 320         return !!r->objects->commit_graph;
 321 }
 322
 323 int generation_numbers_enabled(struct repository *r)
 324 {
 325         uint32_t first_generation;
 326         struct commit_graph *g;
 327         if (!prepare_commit_graph(r))
 328                return 0;
 329
 330         g = r->objects->commit_graph;
 331
 332         if (!g->num_commits)
 333                 return 0;
 334
 335         first_generation = get_be32(g->chunk_commit_data +
 336                                     g->hash_len + 8) >> 2;
 337
 338         return !!first_generation;
 339 }
 340
 341 void close_commit_graph(struct repository *r)
 342 {
 343         free_commit_graph(r->objects->commit_graph);
 344         r->objects->commit_graph = NULL;
 345 }
 346
 347 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 348 {
 349         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 350                             g->chunk_oid_lookup, g->hash_len, pos);
 351 }
 352
 353 static struct commit_list **insert_parent_or_die(struct repository *r,
 354                                                  struct commit_graph *g,
 355                                                  uint64_t pos,
 356                                                  struct commit_list **pptr)
 357 {
 358         struct commit *c;
 359         struct object_id oid;
 360
 361         if (pos >= g->num_commits)
 362                 die("invalid parent position %"PRIu64, pos);
 363
 364         hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
 365         c = lookup_commit(r, &oid);
 366         if (!c)
 367                 die(_("could not find commit %s"), oid_to_hex(&oid));
 368         c->graph_pos = pos;
 369         return &commit_list_insert(c, pptr)->next;
 370 }
 371
 372 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 373 {
 374         const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
 375         item->graph_pos = pos;
 376         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 377 }
 378
 379 static int fill_commit_in_graph(struct repository *r,
 380                                 struct commit *item,
 381                                 struct commit_graph *g, uint32_t pos)
 382 {
 383         uint32_t edge_value;
 384         uint32_t *parent_data_ptr;
 385         uint64_t date_low, date_high;
 386         struct commit_list **pptr;
 387         const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
 388
 389         item->object.parsed = 1;
 390         item->graph_pos = pos;
 391
 392         item->maybe_tree = NULL;
 393
 394         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 395         date_low = get_be32(commit_data + g->hash_len + 12);
 396         item->date = (timestamp_t)((date_high << 32) | date_low);
 397
 398         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 399
 400         pptr = &item->parents;
 401
 402         edge_value = get_be32(commit_data + g->hash_len);
 403         if (edge_value == GRAPH_PARENT_NONE)
 404                 return 1;
 405         pptr = insert_parent_or_die(r, g, edge_value, pptr);
 406
 407         edge_value = get_be32(commit_data + g->hash_len + 4);
 408         if (edge_value == GRAPH_PARENT_NONE)
 409                 return 1;
 410         if (!(edge_value & GRAPH_EXTRA_EDGES_NEEDED)) {
 411                 pptr = insert_parent_or_die(r, g, edge_value, pptr);
 412                 return 1;
 413         }
 414
 415         parent_data_ptr = (uint32_t*)(g->chunk_extra_edges +
 416                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 417         do {
 418                 edge_value = get_be32(parent_data_ptr);
 419                 pptr = insert_parent_or_die(r, g,
 420                                             edge_value & GRAPH_EDGE_LAST_MASK,
 421                                             pptr);
 422                 parent_data_ptr++;
 423         } while (!(edge_value & GRAPH_LAST_EDGE));
 424
 425         return 1;
 426 }
 427
 428 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 429 {
 430         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 431                 *pos = item->graph_pos;
 432                 return 1;
 433         } else {
 434                 return bsearch_graph(g, &(item->object.oid), pos);
 435         }
 436 }
 437
 438 static int parse_commit_in_graph_one(struct repository *r,
 439                                      struct commit_graph *g,
 440                                      struct commit *item)
 441 {
 442         uint32_t pos;
 443
 444         if (item->object.parsed)
 445                 return 1;
 446
 447         if (find_commit_in_graph(item, g, &pos))
 448                 return fill_commit_in_graph(r, item, g, pos);
 449
 450         return 0;
 451 }
 452
 453 int parse_commit_in_graph(struct repository *r, struct commit *item)
 454 {
 455         if (!prepare_commit_graph(r))
 456                 return 0;
 457         return parse_commit_in_graph_one(r, r->objects->commit_graph, item);
 458 }
 459
 460 void load_commit_graph_info(struct repository *r, struct commit *item)
 461 {
 462         uint32_t pos;
 463         if (!prepare_commit_graph(r))
 464                 return;
 465         if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
 466                 fill_commit_graph_info(item, r->objects->commit_graph, pos);
 467 }
 468
 469 static struct tree *load_tree_for_commit(struct repository *r,
 470                                          struct commit_graph *g,
 471                                          struct commit *c)
 472 {
 473         struct object_id oid;
 474         const unsigned char *commit_data = g->chunk_commit_data +
 475                                            GRAPH_DATA_WIDTH * (c->graph_pos);
 476
 477         hashcpy(oid.hash, commit_data);
 478         c->maybe_tree = lookup_tree(r, &oid);
 479
 480         return c->maybe_tree;
 481 }
 482
 483 static struct tree *get_commit_tree_in_graph_one(struct repository *r,
 484                                                  struct commit_graph *g,
 485                                                  const struct commit *c)
 486 {
 487         if (c->maybe_tree)
 488                 return c->maybe_tree;
 489         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 490                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 491
 492         return load_tree_for_commit(r, g, (struct commit *)c);
 493 }
 494
 495 struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
 496 {
 497         return get_commit_tree_in_graph_one(r, r->objects->commit_graph, c);
 498 }
 499
 500 static void write_graph_chunk_fanout(struct hashfile *f,
 501                                      struct commit **commits,
 502                                      int nr_commits,
 503                                      struct progress *progress,
 504                                      uint64_t *progress_cnt)
 505 {
 506         int i, count = 0;
 507         struct commit **list = commits;
 508
 509         /*
 510          * Write the first-level table (the list is sorted,
 511          * but we use a 256-entry lookup to be able to avoid
 512          * having to do eight extra binary search iterations).
 513          */
 514         for (i = 0; i < 256; i++) {
 515                 while (count < nr_commits) {
 516                         if ((*list)->object.oid.hash[0] != i)
 517                                 break;
 518                         display_progress(progress, ++*progress_cnt);
 519                         count++;
 520                         list++;
 521                 }
 522
 523                 hashwrite_be32(f, count);
 524         }
 525 }
 526
 527 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 528                                    struct commit **commits, int nr_commits,
 529                                    struct progress *progress,
 530                                    uint64_t *progress_cnt)
 531 {
 532         struct commit **list = commits;
 533         int count;
 534         for (count = 0; count < nr_commits; count++, list++) {
 535                 display_progress(progress, ++*progress_cnt);
 536                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 537         }
 538 }
 539
 540 static const unsigned char *commit_to_sha1(size_t index, void *table)
 541 {
 542         struct commit **commits = table;
 543         return commits[index]->object.oid.hash;
 544 }
 545
 546 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 547                                    struct commit **commits, int nr_commits,
 548                                    struct progress *progress,
 549                                    uint64_t *progress_cnt)
 550 {
 551         struct commit **list = commits;
 552         struct commit **last = commits + nr_commits;
 553         uint32_t num_extra_edges = 0;
 554
 555         while (list < last) {
 556                 struct commit_list *parent;
 557                 int edge_value;
 558                 uint32_t packedDate[2];
 559                 display_progress(progress, ++*progress_cnt);
 560
 561                 parse_commit(*list);
 562                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 563
 564                 parent = (*list)->parents;
 565
 566                 if (!parent)
 567                         edge_value = GRAPH_PARENT_NONE;
 568                 else {
 569                         edge_value = sha1_pos(parent->item->object.oid.hash,
 570                                               commits,
 571                                               nr_commits,
 572                                               commit_to_sha1);
 573
 574                         if (edge_value < 0)
 575                                 BUG("missing parent %s for commit %s",
 576                                     oid_to_hex(&parent->item->object.oid),
 577                                     oid_to_hex(&(*list)->object.oid));
 578                 }
 579
 580                 hashwrite_be32(f, edge_value);
 581
 582                 if (parent)
 583                         parent = parent->next;
 584
 585                 if (!parent)
 586                         edge_value = GRAPH_PARENT_NONE;
 587                 else if (parent->next)
 588                         edge_value = GRAPH_EXTRA_EDGES_NEEDED | num_extra_edges;
 589                 else {
 590                         edge_value = sha1_pos(parent->item->object.oid.hash,
 591                                               commits,
 592                                               nr_commits,
 593                                               commit_to_sha1);
 594                         if (edge_value < 0)
 595                                 BUG("missing parent %s for commit %s",
 596                                     oid_to_hex(&parent->item->object.oid),
 597                                     oid_to_hex(&(*list)->object.oid));
 598                 }
 599
 600                 hashwrite_be32(f, edge_value);
 601
 602                 if (edge_value & GRAPH_EXTRA_EDGES_NEEDED) {
 603                         do {
 604                                 num_extra_edges++;
 605                                 parent = parent->next;
 606                         } while (parent);
 607                 }
 608
 609                 if (sizeof((*list)->date) > 4)
 610                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 611                 else
 612                         packedDate[0] = 0;
 613
 614                 packedDate[0] |= htonl((*list)->generation << 2);
 615
 616                 packedDate[1] = htonl((*list)->date);
 617                 hashwrite(f, packedDate, 8);
 618
 619                 list++;
 620         }
 621 }
 622
 623 static void write_graph_chunk_extra_edges(struct hashfile *f,
 624                                           struct commit **commits,
 625                                           int nr_commits,
 626                                           struct progress *progress,
 627                                           uint64_t *progress_cnt)
 628 {
 629         struct commit **list = commits;
 630         struct commit **last = commits + nr_commits;
 631         struct commit_list *parent;
 632
 633         while (list < last) {
 634                 int num_parents = 0;
 635
 636                 display_progress(progress, ++*progress_cnt);
 637
 638                 for (parent = (*list)->parents; num_parents < 3 && parent;
 639                      parent = parent->next)
 640                         num_parents++;
 641
 642                 if (num_parents <= 2) {
 643                         list++;
 644                         continue;
 645                 }
 646
 647                 /* Since num_parents > 2, this initializer is safe. */
 648                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 649                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 650                                                   commits,
 651                                                   nr_commits,
 652                                                   commit_to_sha1);
 653
 654                         if (edge_value < 0)
 655                                 BUG("missing parent %s for commit %s",
 656                                     oid_to_hex(&parent->item->object.oid),
 657                                     oid_to_hex(&(*list)->object.oid));
 658                         else if (!parent->next)
 659                                 edge_value |= GRAPH_LAST_EDGE;
 660
 661                         hashwrite_be32(f, edge_value);
 662                 }
 663
 664                 list++;
 665         }
 666 }
 667
 668 static int commit_compare(const void *_a, const void *_b)
 669 {
 670         const struct object_id *a = (const struct object_id *)_a;
 671         const struct object_id *b = (const struct object_id *)_b;
 672         return oidcmp(a, b);
 673 }
 674
 675 struct packed_commit_list {
 676         struct commit **list;
 677         int nr;
 678         int alloc;
 679 };
 680
 681 struct packed_oid_list {
 682         struct object_id *list;
 683         int nr;
 684         int alloc;
 685         struct progress *progress;
 686         int progress_done;
 687 };
 688
 689 static int add_packed_commits(const struct object_id *oid,
 690                               struct packed_git *pack,
 691                               uint32_t pos,
 692                               void *data)
 693 {
 694         struct packed_oid_list *list = (struct packed_oid_list*)data;
 695         enum object_type type;
 696         off_t offset = nth_packed_object_offset(pack, pos);
 697         struct object_info oi = OBJECT_INFO_INIT;
 698
 699         if (list->progress)
 700                 display_progress(list->progress, ++list->progress_done);
 701
 702         oi.typep = &type;
 703         if (packed_object_info(the_repository, pack, offset, &oi) < 0)
 704                 die(_("unable to get type of object %s"), oid_to_hex(oid));
 705
 706         if (type != OBJ_COMMIT)
 707                 return 0;
 708
 709         ALLOC_GROW(list->list, list->nr + 1, list->alloc);
 710         oidcpy(&(list->list[list->nr]), oid);
 711         list->nr++;
 712
 713         return 0;
 714 }
 715
 716 static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
 717 {
 718         struct commit_list *parent;
 719         for (parent = commit->parents; parent; parent = parent->next) {
 720                 if (!(parent->item->object.flags & UNINTERESTING)) {
 721                         ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
 722                         oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
 723                         oids->nr++;
 724                         parent->item->object.flags |= UNINTERESTING;
 725                 }
 726         }
 727 }
 728
 729 static void close_reachable(struct packed_oid_list *oids, int report_progress)
 730 {
 731         int i;
 732         struct commit *commit;
 733         struct progress *progress = NULL;
 734
 735         if (report_progress)
 736                 progress = start_delayed_progress(
 737                         _("Loading known commits in commit graph"), oids->nr);
 738         for (i = 0; i < oids->nr; i++) {
 739                 display_progress(progress, i + 1);
 740                 commit = lookup_commit(the_repository, &oids->list[i]);
 741                 if (commit)
 742                         commit->object.flags |= UNINTERESTING;
 743         }
 744         stop_progress(&progress);
 745
 746         /*
 747          * As this loop runs, oids->nr may grow, but not more
 748          * than the number of missing commits in the reachable
 749          * closure.
 750          */
 751         if (report_progress)
 752                 progress = start_delayed_progress(
 753                         _("Expanding reachable commits in commit graph"), oids->nr);
 754         for (i = 0; i < oids->nr; i++) {
 755                 display_progress(progress, i + 1);
 756                 commit = lookup_commit(the_repository, &oids->list[i]);
 757
 758                 if (commit && !parse_commit(commit))
 759                         add_missing_parents(oids, commit);
 760         }
 761         stop_progress(&progress);
 762
 763         if (report_progress)
 764                 progress = start_delayed_progress(
 765                         _("Clearing commit marks in commit graph"), oids->nr);
 766         for (i = 0; i < oids->nr; i++) {
 767                 display_progress(progress, i + 1);
 768                 commit = lookup_commit(the_repository, &oids->list[i]);
 769
 770                 if (commit)
 771                         commit->object.flags &= ~UNINTERESTING;
 772         }
 773         stop_progress(&progress);
 774 }
 775
 776 static void compute_generation_numbers(struct packed_commit_list* commits,
 777                                        int report_progress)
 778 {
 779         int i;
 780         struct commit_list *list = NULL;
 781         struct progress *progress = NULL;
 782
 783         if (report_progress)
 784                 progress = start_progress(
 785                         _("Computing commit graph generation numbers"),
 786                         commits->nr);
 787         for (i = 0; i < commits->nr; i++) {
 788                 display_progress(progress, i + 1);
 789                 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
 790                     commits->list[i]->generation != GENERATION_NUMBER_ZERO)
 791                         continue;
 792
 793                 commit_list_insert(commits->list[i], &list);
 794                 while (list) {
 795                         struct commit *current = list->item;
 796                         struct commit_list *parent;
 797                         int all_parents_computed = 1;
 798                         uint32_t max_generation = 0;
 799
 800                         for (parent = current->parents; parent; parent = parent->next) {
 801                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 802                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 803                                         all_parents_computed = 0;
 804                                         commit_list_insert(parent->item, &list);
 805                                         break;
 806                                 } else if (parent->item->generation > max_generation) {
 807                                         max_generation = parent->item->generation;
 808                                 }
 809                         }
 810
 811                         if (all_parents_computed) {
 812                                 current->generation = max_generation + 1;
 813                                 pop_commit(&list);
 814
 815                                 if (current->generation > GENERATION_NUMBER_MAX)
 816                                         current->generation = GENERATION_NUMBER_MAX;
 817                         }
 818                 }
 819         }
 820         stop_progress(&progress);
 821 }
 822
 823 static int add_ref_to_list(const char *refname,
 824                            const struct object_id *oid,
 825                            int flags, void *cb_data)
 826 {
 827         struct string_list *list = (struct string_list *)cb_data;
 828
 829         string_list_append(list, oid_to_hex(oid));
 830         return 0;
 831 }
 832
 833 void write_commit_graph_reachable(const char *obj_dir, int append,
 834                                   int report_progress)
 835 {
 836         struct string_list list = STRING_LIST_INIT_DUP;
 837
 838         for_each_ref(add_ref_to_list, &list);
 839         write_commit_graph(obj_dir, NULL, &list, append, report_progress);
 840
 841         string_list_clear(&list, 0);
 842 }
 843
 844 void write_commit_graph(const char *obj_dir,
 845                         struct string_list *pack_indexes,
 846                         struct string_list *commit_hex,
 847                         int append, int report_progress)
 848 {
 849         struct packed_oid_list oids;
 850         struct packed_commit_list commits;
 851         struct hashfile *f;
 852         uint32_t i, count_distinct = 0;
 853         char *graph_name;
 854         struct lock_file lk = LOCK_INIT;
 855         uint32_t chunk_ids[5];
 856         uint64_t chunk_offsets[5];
 857         int num_chunks;
 858         int num_extra_edges;
 859         struct commit_list *parent;
 860         struct progress *progress = NULL;
 861         const unsigned hashsz = the_hash_algo->rawsz;
 862         uint64_t progress_cnt = 0;
 863         struct strbuf progress_title = STRBUF_INIT;
 864         unsigned long approx_nr_objects;
 865
 866         if (!commit_graph_compatible(the_repository))
 867                 return;
 868
 869         oids.nr = 0;
 870         approx_nr_objects = approximate_object_count();
 871         oids.alloc = approx_nr_objects / 32;
 872         oids.progress = NULL;
 873         oids.progress_done = 0;
 874
 875         if (append) {
 876                 prepare_commit_graph_one(the_repository, obj_dir);
 877                 if (the_repository->objects->commit_graph)
 878                         oids.alloc += the_repository->objects->commit_graph->num_commits;
 879         }
 880
 881         if (oids.alloc < 1024)
 882                 oids.alloc = 1024;
 883         ALLOC_ARRAY(oids.list, oids.alloc);
 884
 885         if (append && the_repository->objects->commit_graph) {
 886                 struct commit_graph *commit_graph =
 887                         the_repository->objects->commit_graph;
 888                 for (i = 0; i < commit_graph->num_commits; i++) {
 889                         const unsigned char *hash = commit_graph->chunk_oid_lookup +
 890                                 commit_graph->hash_len * i;
 891                         hashcpy(oids.list[oids.nr++].hash, hash);
 892                 }
 893         }
 894
 895         if (pack_indexes) {
 896                 struct strbuf packname = STRBUF_INIT;
 897                 int dirlen;
 898                 strbuf_addf(&packname, "%s/pack/", obj_dir);
 899                 dirlen = packname.len;
 900                 if (report_progress) {
 901                         strbuf_addf(&progress_title,
 902                                     Q_("Finding commits for commit graph in %d pack",
 903                                        "Finding commits for commit graph in %d packs",
 904                                        pack_indexes->nr),
 905                                     pack_indexes->nr);
 906                         oids.progress = start_delayed_progress(progress_title.buf, 0);
 907                         oids.progress_done = 0;
 908                 }
 909                 for (i = 0; i < pack_indexes->nr; i++) {
 910                         struct packed_git *p;
 911                         strbuf_setlen(&packname, dirlen);
 912                         strbuf_addstr(&packname, pack_indexes->items[i].string);
 913                         p = add_packed_git(packname.buf, packname.len, 1);
 914                         if (!p)
 915                                 die(_("error adding pack %s"), packname.buf);
 916                         if (open_pack_index(p))
 917                                 die(_("error opening index for %s"), packname.buf);
 918                         for_each_object_in_pack(p, add_packed_commits, &oids,
 919                                                 FOR_EACH_OBJECT_PACK_ORDER);
 920                         close_pack(p);
 921                         free(p);
 922                 }
 923                 stop_progress(&oids.progress);
 924                 strbuf_reset(&progress_title);
 925                 strbuf_release(&packname);
 926         }
 927
 928         if (commit_hex) {
 929                 if (report_progress) {
 930                         strbuf_addf(&progress_title,
 931                                     Q_("Finding commits for commit graph from %d ref",
 932                                        "Finding commits for commit graph from %d refs",
 933                                        commit_hex->nr),
 934                                     commit_hex->nr);
 935                         progress = start_delayed_progress(progress_title.buf,
 936                                                           commit_hex->nr);
 937                 }
 938                 for (i = 0; i < commit_hex->nr; i++) {
 939                         const char *end;
 940                         struct object_id oid;
 941                         struct commit *result;
 942
 943                         display_progress(progress, i + 1);
 944                         if (commit_hex->items[i].string &&
 945                             parse_oid_hex(commit_hex->items[i].string, &oid, &end))
 946                                 continue;
 947
 948                         result = lookup_commit_reference_gently(the_repository, &oid, 1);
 949
 950                         if (result) {
 951                                 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
 952                                 oidcpy(&oids.list[oids.nr], &(result->object.oid));
 953                                 oids.nr++;
 954                         }
 955                 }
 956                 stop_progress(&progress);
 957                 strbuf_reset(&progress_title);
 958         }
 959
 960         if (!pack_indexes && !commit_hex) {
 961                 if (report_progress)
 962                         oids.progress = start_delayed_progress(
 963                                 _("Finding commits for commit graph among packed objects"),
 964                                 approx_nr_objects);
 965                 for_each_packed_object(add_packed_commits, &oids,
 966                                        FOR_EACH_OBJECT_PACK_ORDER);
 967                 if (oids.progress_done < approx_nr_objects)
 968                         display_progress(oids.progress, approx_nr_objects);
 969                 stop_progress(&oids.progress);
 970         }
 971
 972         close_reachable(&oids, report_progress);
 973
 974         if (report_progress)
 975                 progress = start_delayed_progress(
 976                         _("Counting distinct commits in commit graph"),
 977                         oids.nr);
 978         display_progress(progress, 0); /* TODO: Measure QSORT() progress */
 979         QSORT(oids.list, oids.nr, commit_compare);
 980         count_distinct = 1;
 981         for (i = 1; i < oids.nr; i++) {
 982                 display_progress(progress, i + 1);
 983                 if (!oideq(&oids.list[i - 1], &oids.list[i]))
 984                         count_distinct++;
 985         }
 986         stop_progress(&progress);
 987
 988         if (count_distinct >= GRAPH_EDGE_LAST_MASK)
 989                 die(_("the commit graph format cannot write %d commits"), count_distinct);
 990
 991         commits.nr = 0;
 992         commits.alloc = count_distinct;
 993         ALLOC_ARRAY(commits.list, commits.alloc);
 994
 995         num_extra_edges = 0;
 996         if (report_progress)
 997                 progress = start_delayed_progress(
 998                         _("Finding extra edges in commit graph"),
 999                         oids.nr);
1000         for (i = 0; i < oids.nr; i++) {
1001                 int num_parents = 0;
1002                 display_progress(progress, i + 1);
1003                 if (i > 0 && oideq(&oids.list[i - 1], &oids.list[i]))
1004                         continue;
1005
1006                 commits.list[commits.nr] = lookup_commit(the_repository, &oids.list[i]);
1007                 parse_commit(commits.list[commits.nr]);
1008
1009                 for (parent = commits.list[commits.nr]->parents;
1010                      parent; parent = parent->next)
1011                         num_parents++;
1012
1013                 if (num_parents > 2)
1014                         num_extra_edges += num_parents - 1;
1015
1016                 commits.nr++;
1017         }
1018         num_chunks = num_extra_edges ? 4 : 3;
1019         stop_progress(&progress);
1020
1021         if (commits.nr >= GRAPH_EDGE_LAST_MASK)
1022                 die(_("too many commits to write graph"));
1023
1024         compute_generation_numbers(&commits, report_progress);
1025
1026         graph_name = get_commit_graph_filename(obj_dir);
1027         if (safe_create_leading_directories(graph_name)) {
1028                 UNLEAK(graph_name);
1029                 die_errno(_("unable to create leading directories of %s"),
1030                           graph_name);
1031         }
1032
1033         hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
1034         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
1035
1036         hashwrite_be32(f, GRAPH_SIGNATURE);
1037
1038         hashwrite_u8(f, GRAPH_VERSION);
1039         hashwrite_u8(f, oid_version());
1040         hashwrite_u8(f, num_chunks);
1041         hashwrite_u8(f, 0); /* unused padding byte */
1042
1043         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
1044         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
1045         chunk_ids[2] = GRAPH_CHUNKID_DATA;
1046         if (num_extra_edges)
1047                 chunk_ids[3] = GRAPH_CHUNKID_EXTRAEDGES;
1048         else
1049                 chunk_ids[3] = 0;
1050         chunk_ids[4] = 0;
1051
1052         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
1053         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
1054         chunk_offsets[2] = chunk_offsets[1] + hashsz * commits.nr;
1055         chunk_offsets[3] = chunk_offsets[2] + (hashsz + 16) * commits.nr;
1056         chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
1057
1058         for (i = 0; i <= num_chunks; i++) {
1059                 uint32_t chunk_write[3];
1060
1061                 chunk_write[0] = htonl(chunk_ids[i]);
1062                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
1063                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
1064                 hashwrite(f, chunk_write, 12);
1065         }
1066
1067         if (report_progress) {
1068                 strbuf_addf(&progress_title,
1069                             Q_("Writing out commit graph in %d pass",
1070                                "Writing out commit graph in %d passes",
1071                                num_chunks),
1072                             num_chunks);
1073                 progress = start_delayed_progress(
1074                         progress_title.buf,
1075                         num_chunks * commits.nr);
1076         }
1077         write_graph_chunk_fanout(f, commits.list, commits.nr, progress, &progress_cnt);
1078         write_graph_chunk_oids(f, hashsz, commits.list, commits.nr, progress, &progress_cnt);
1079         write_graph_chunk_data(f, hashsz, commits.list, commits.nr, progress, &progress_cnt);
1080         if (num_extra_edges)
1081                 write_graph_chunk_extra_edges(f, commits.list, commits.nr, progress, &progress_cnt);
1082         stop_progress(&progress);
1083         strbuf_release(&progress_title);
1084
1085         close_commit_graph(the_repository);
1086         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
1087         commit_lock_file(&lk);
1088
1089         free(graph_name);
1090         free(commits.list);
1091         free(oids.list);
1092 }
1093
1094 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
1095 static int verify_commit_graph_error;
1096
1097 static void graph_report(const char *fmt, ...)
1098 {
1099         va_list ap;
1100
1101         verify_commit_graph_error = 1;
1102         va_start(ap, fmt);
1103         vfprintf(stderr, fmt, ap);
1104         fprintf(stderr, "\n");
1105         va_end(ap);
1106 }
1107
1108 #define GENERATION_ZERO_EXISTS 1
1109 #define GENERATION_NUMBER_EXISTS 2
1110
1111 int verify_commit_graph(struct repository *r, struct commit_graph *g)
1112 {
1113         uint32_t i, cur_fanout_pos = 0;
1114         struct object_id prev_oid, cur_oid, checksum;
1115         int generation_zero = 0;
1116         struct hashfile *f;
1117         int devnull;
1118         struct progress *progress = NULL;
1119
1120         if (!g) {
1121                 graph_report("no commit-graph file loaded");
1122                 return 1;
1123         }
1124
1125         verify_commit_graph_error = verify_commit_graph_lite(g);
1126         if (verify_commit_graph_error)
1127                 return verify_commit_graph_error;
1128
1129         devnull = open("/dev/null", O_WRONLY);
1130         f = hashfd(devnull, NULL);
1131         hashwrite(f, g->data, g->data_len - g->hash_len);
1132         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
1133         if (!hasheq(checksum.hash, g->data + g->data_len - g->hash_len)) {
1134                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
1135                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
1136         }
1137
1138         for (i = 0; i < g->num_commits; i++) {
1139                 struct commit *graph_commit;
1140
1141                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1142
1143                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
1144                         graph_report("commit-graph has incorrect OID order: %s then %s",
1145                                      oid_to_hex(&prev_oid),
1146                                      oid_to_hex(&cur_oid));
1147
1148                 oidcpy(&prev_oid, &cur_oid);
1149
1150                 while (cur_oid.hash[0] > cur_fanout_pos) {
1151                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1152
1153                         if (i != fanout_value)
1154                                 graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
1155                                              cur_fanout_pos, fanout_value, i);
1156                         cur_fanout_pos++;
1157                 }
1158
1159                 graph_commit = lookup_commit(r, &cur_oid);
1160                 if (!parse_commit_in_graph_one(r, g, graph_commit))
1161                         graph_report("failed to parse %s from commit-graph",
1162                                      oid_to_hex(&cur_oid));
1163         }
1164
1165         while (cur_fanout_pos < 256) {
1166                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1167
1168                 if (g->num_commits != fanout_value)
1169                         graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
1170                                      cur_fanout_pos, fanout_value, i);
1171
1172                 cur_fanout_pos++;
1173         }
1174
1175         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
1176                 return verify_commit_graph_error;
1177
1178         progress = start_progress(_("Verifying commits in commit graph"),
1179                                   g->num_commits);
1180         for (i = 0; i < g->num_commits; i++) {
1181                 struct commit *graph_commit, *odb_commit;
1182                 struct commit_list *graph_parents, *odb_parents;
1183                 uint32_t max_generation = 0;
1184
1185                 display_progress(progress, i + 1);
1186                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1187
1188                 graph_commit = lookup_commit(r, &cur_oid);
1189                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
1190                 if (parse_commit_internal(odb_commit, 0, 0)) {
1191                         graph_report("failed to parse %s from object database",
1192                                      oid_to_hex(&cur_oid));
1193                         continue;
1194                 }
1195
1196                 if (!oideq(&get_commit_tree_in_graph_one(r, g, graph_commit)->object.oid,
1197                            get_commit_tree_oid(odb_commit)))
1198                         graph_report("root tree OID for commit %s in commit-graph is %s != %s",
1199                                      oid_to_hex(&cur_oid),
1200                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
1201                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
1202
1203                 graph_parents = graph_commit->parents;
1204                 odb_parents = odb_commit->parents;
1205
1206                 while (graph_parents) {
1207                         if (odb_parents == NULL) {
1208                                 graph_report("commit-graph parent list for commit %s is too long",
1209                                              oid_to_hex(&cur_oid));
1210                                 break;
1211                         }
1212
1213                         if (!oideq(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
1214                                 graph_report("commit-graph parent for %s is %s != %s",
1215                                              oid_to_hex(&cur_oid),
1216                                              oid_to_hex(&graph_parents->item->object.oid),
1217                                              oid_to_hex(&odb_parents->item->object.oid));
1218
1219                         if (graph_parents->item->generation > max_generation)
1220                                 max_generation = graph_parents->item->generation;
1221
1222                         graph_parents = graph_parents->next;
1223                         odb_parents = odb_parents->next;
1224                 }
1225
1226                 if (odb_parents != NULL)
1227                         graph_report("commit-graph parent list for commit %s terminates early",
1228                                      oid_to_hex(&cur_oid));
1229
1230                 if (!graph_commit->generation) {
1231                         if (generation_zero == GENERATION_NUMBER_EXISTS)
1232                                 graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
1233                                              oid_to_hex(&cur_oid));
1234                         generation_zero = GENERATION_ZERO_EXISTS;
1235                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1236                         graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
1237                                      oid_to_hex(&cur_oid));
1238
1239                 if (generation_zero == GENERATION_ZERO_EXISTS)
1240                         continue;
1241
1242                 /*
1243                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1244                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1245                  * extra logic in the following condition.
1246                  */
1247                 if (max_generation == GENERATION_NUMBER_MAX)
1248                         max_generation--;
1249
1250                 if (graph_commit->generation != max_generation + 1)
1251                         graph_report("commit-graph generation for commit %s is %u != %u",
1252                                      oid_to_hex(&cur_oid),
1253                                      graph_commit->generation,
1254                                      max_generation + 1);
1255
1256                 if (graph_commit->date != odb_commit->date)
1257                         graph_report("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime,
1258                                      oid_to_hex(&cur_oid),
1259                                      graph_commit->date,
1260                                      odb_commit->date);
1261         }
1262         stop_progress(&progress);
1263
1264         return verify_commit_graph_error;
1265 }
1266
1267 void free_commit_graph(struct commit_graph *g)
1268 {
1269         if (!g)
1270                 return;
1271         if (g->graph_fd >= 0) {
1272                 munmap((void *)g->data, g->data_len);
1273                 g->data = NULL;
1274                 close(g->graph_fd);
1275         }
1276         free(g);
1277 }