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 int open_commit_graph(const char *graph_file, int *fd, struct stat *st)
  84 {
  85         *fd = git_open(graph_file);
  86         if (*fd < 0)
  87                 return 0;
  88         if (fstat(*fd, st)) {
  89                 close(*fd);
  90                 return 0;
  91         }
  92         return 1;
  93 }
  94
  95 struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st)
  96 {
  97         void *graph_map;
  98         size_t graph_size;
  99         struct commit_graph *ret;
 100
 101         graph_size = xsize_t(st->st_size);
 102
 103         if (graph_size < GRAPH_MIN_SIZE) {
 104                 close(fd);
 105                 error(_("commit-graph file is too small"));
 106                 return NULL;
 107         }
 108         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
 109         ret = parse_commit_graph(graph_map, fd, graph_size);
 110
 111         if (!ret) {
 112                 munmap(graph_map, graph_size);
 113                 close(fd);
 114         }
 115
 116         return ret;
 117 }
 118
 119 static int verify_commit_graph_lite(struct commit_graph *g)
 120 {
 121         /*
 122          * Basic validation shared between parse_commit_graph()
 123          * which'll be called every time the graph is used, and the
 124          * much more expensive verify_commit_graph() used by
 125          * "commit-graph verify".
 126          *
 127          * There should only be very basic checks here to ensure that
 128          * we don't e.g. segfault in fill_commit_in_graph(), but
 129          * because this is a very hot codepath nothing that e.g. loops
 130          * over g->num_commits, or runs a checksum on the commit-graph
 131          * itself.
 132          */
 133         if (!g->chunk_oid_fanout) {
 134                 error("commit-graph is missing the OID Fanout chunk");
 135                 return 1;
 136         }
 137         if (!g->chunk_oid_lookup) {
 138                 error("commit-graph is missing the OID Lookup chunk");
 139                 return 1;
 140         }
 141         if (!g->chunk_commit_data) {
 142                 error("commit-graph is missing the Commit Data chunk");
 143                 return 1;
 144         }
 145
 146         return 0;
 147 }
 148
 149 struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 150                                         size_t graph_size)
 151 {
 152         const unsigned char *data, *chunk_lookup;
 153         uint32_t i;
 154         struct commit_graph *graph;
 155         uint64_t last_chunk_offset;
 156         uint32_t last_chunk_id;
 157         uint32_t graph_signature;
 158         unsigned char graph_version, hash_version;
 159
 160         if (!graph_map)
 161                 return NULL;
 162
 163         if (graph_size < GRAPH_MIN_SIZE)
 164                 return NULL;
 165
 166         data = (const unsigned char *)graph_map;
 167
 168         graph_signature = get_be32(data);
 169         if (graph_signature != GRAPH_SIGNATURE) {
 170                 error(_("commit-graph signature %X does not match signature %X"),
 171                       graph_signature, GRAPH_SIGNATURE);
 172                 return NULL;
 173         }
 174
 175         graph_version = *(unsigned char*)(data + 4);
 176         if (graph_version != GRAPH_VERSION) {
 177                 error(_("commit-graph version %X does not match version %X"),
 178                       graph_version, GRAPH_VERSION);
 179                 return NULL;
 180         }
 181
 182         hash_version = *(unsigned char*)(data + 5);
 183         if (hash_version != oid_version()) {
 184                 error(_("commit-graph hash version %X does not match version %X"),
 185                       hash_version, oid_version());
 186                 return NULL;
 187         }
 188
 189         graph = alloc_commit_graph();
 190
 191         graph->hash_len = the_hash_algo->rawsz;
 192         graph->num_chunks = *(unsigned char*)(data + 6);
 193         graph->graph_fd = fd;
 194         graph->data = graph_map;
 195         graph->data_len = graph_size;
 196
 197         last_chunk_id = 0;
 198         last_chunk_offset = 8;
 199         chunk_lookup = data + 8;
 200         for (i = 0; i < graph->num_chunks; i++) {
 201                 uint32_t chunk_id;
 202                 uint64_t chunk_offset;
 203                 int chunk_repeated = 0;
 204
 205                 if (data + graph_size - chunk_lookup <
 206                     GRAPH_CHUNKLOOKUP_WIDTH) {
 207                         error(_("commit-graph chunk lookup table entry missing; file may be incomplete"));
 208                         free(graph);
 209                         return NULL;
 210                 }
 211
 212                 chunk_id = get_be32(chunk_lookup + 0);
 213                 chunk_offset = get_be64(chunk_lookup + 4);
 214
 215                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 216
 217                 if (chunk_offset > graph_size - the_hash_algo->rawsz) {
 218                         error(_("commit-graph improper chunk offset %08x%08x"), (uint32_t)(chunk_offset >> 32),
 219                               (uint32_t)chunk_offset);
 220                         free(graph);
 221                         return NULL;
 222                 }
 223
 224                 switch (chunk_id) {
 225                 case GRAPH_CHUNKID_OIDFANOUT:
 226                         if (graph->chunk_oid_fanout)
 227                                 chunk_repeated = 1;
 228                         else
 229                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 230                         break;
 231
 232                 case GRAPH_CHUNKID_OIDLOOKUP:
 233                         if (graph->chunk_oid_lookup)
 234                                 chunk_repeated = 1;
 235                         else
 236                                 graph->chunk_oid_lookup = data + chunk_offset;
 237                         break;
 238
 239                 case GRAPH_CHUNKID_DATA:
 240                         if (graph->chunk_commit_data)
 241                                 chunk_repeated = 1;
 242                         else
 243                                 graph->chunk_commit_data = data + chunk_offset;
 244                         break;
 245
 246                 case GRAPH_CHUNKID_EXTRAEDGES:
 247                         if (graph->chunk_extra_edges)
 248                                 chunk_repeated = 1;
 249                         else
 250                                 graph->chunk_extra_edges = data + chunk_offset;
 251                         break;
 252                 }
 253
 254                 if (chunk_repeated) {
 255                         error(_("commit-graph chunk id %08x appears multiple times"), chunk_id);
 256                         free(graph);
 257                         return NULL;
 258                 }
 259
 260                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 261                 {
 262                         graph->num_commits = (chunk_offset - last_chunk_offset)
 263                                              / graph->hash_len;
 264                 }
 265
 266                 last_chunk_id = chunk_id;
 267                 last_chunk_offset = chunk_offset;
 268         }
 269
 270         if (verify_commit_graph_lite(graph))
 271                 return NULL;
 272
 273         return graph;
 274 }
 275
 276 static struct commit_graph *load_commit_graph_one(const char *graph_file)
 277 {
 278
 279         struct stat st;
 280         int fd;
 281         int open_ok = open_commit_graph(graph_file, &fd, &st);
 282
 283         if (!open_ok)
 284                 return NULL;
 285
 286         return load_commit_graph_one_fd_st(fd, &st);
 287 }
 288
 289 static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
 290 {
 291         char *graph_name;
 292
 293         if (r->objects->commit_graph)
 294                 return;
 295
 296         graph_name = get_commit_graph_filename(obj_dir);
 297         r->objects->commit_graph =
 298                 load_commit_graph_one(graph_name);
 299
 300         FREE_AND_NULL(graph_name);
 301 }
 302
 303 /*
 304  * Return 1 if commit_graph is non-NULL, and 0 otherwise.
 305  *
 306  * On the first invocation, this function attemps to load the commit
 307  * graph if the_repository is configured to have one.
 308  */
 309 static int prepare_commit_graph(struct repository *r)
 310 {
 311         struct object_directory *odb;
 312         int config_value;
 313
 314         if (git_env_bool(GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD, 0))
 315                 die("dying as requested by the '%s' variable on commit-graph load!",
 316                     GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD);
 317
 318         if (r->objects->commit_graph_attempted)
 319                 return !!r->objects->commit_graph;
 320         r->objects->commit_graph_attempted = 1;
 321
 322         if (!git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
 323             (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
 324             !config_value))
 325                 /*
 326                  * This repository is not configured to use commit graphs, so
 327                  * do not load one. (But report commit_graph_attempted anyway
 328                  * so that commit graph loading is not attempted again for this
 329                  * repository.)
 330                  */
 331                 return 0;
 332
 333         if (!commit_graph_compatible(r))
 334                 return 0;
 335
 336         prepare_alt_odb(r);
 337         for (odb = r->objects->odb;
 338              !r->objects->commit_graph && odb;
 339              odb = odb->next)
 340                 prepare_commit_graph_one(r, odb->path);
 341         return !!r->objects->commit_graph;
 342 }
 343
 344 int generation_numbers_enabled(struct repository *r)
 345 {
 346         uint32_t first_generation;
 347         struct commit_graph *g;
 348         if (!prepare_commit_graph(r))
 349                return 0;
 350
 351         g = r->objects->commit_graph;
 352
 353         if (!g->num_commits)
 354                 return 0;
 355
 356         first_generation = get_be32(g->chunk_commit_data +
 357                                     g->hash_len + 8) >> 2;
 358
 359         return !!first_generation;
 360 }
 361
 362 void close_commit_graph(struct raw_object_store *o)
 363 {
 364         free_commit_graph(o->commit_graph);
 365         o->commit_graph = NULL;
 366 }
 367
 368 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 369 {
 370         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 371                             g->chunk_oid_lookup, g->hash_len, pos);
 372 }
 373
 374 static struct commit_list **insert_parent_or_die(struct repository *r,
 375                                                  struct commit_graph *g,
 376                                                  uint64_t pos,
 377                                                  struct commit_list **pptr)
 378 {
 379         struct commit *c;
 380         struct object_id oid;
 381
 382         if (pos >= g->num_commits)
 383                 die("invalid parent position %"PRIu64, pos);
 384
 385         hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
 386         c = lookup_commit(r, &oid);
 387         if (!c)
 388                 die(_("could not find commit %s"), oid_to_hex(&oid));
 389         c->graph_pos = pos;
 390         return &commit_list_insert(c, pptr)->next;
 391 }
 392
 393 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 394 {
 395         const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
 396         item->graph_pos = pos;
 397         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 398 }
 399
 400 static int fill_commit_in_graph(struct repository *r,
 401                                 struct commit *item,
 402                                 struct commit_graph *g, uint32_t pos)
 403 {
 404         uint32_t edge_value;
 405         uint32_t *parent_data_ptr;
 406         uint64_t date_low, date_high;
 407         struct commit_list **pptr;
 408         const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
 409
 410         item->object.parsed = 1;
 411         item->graph_pos = pos;
 412
 413         item->maybe_tree = NULL;
 414
 415         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 416         date_low = get_be32(commit_data + g->hash_len + 12);
 417         item->date = (timestamp_t)((date_high << 32) | date_low);
 418
 419         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 420
 421         pptr = &item->parents;
 422
 423         edge_value = get_be32(commit_data + g->hash_len);
 424         if (edge_value == GRAPH_PARENT_NONE)
 425                 return 1;
 426         pptr = insert_parent_or_die(r, g, edge_value, pptr);
 427
 428         edge_value = get_be32(commit_data + g->hash_len + 4);
 429         if (edge_value == GRAPH_PARENT_NONE)
 430                 return 1;
 431         if (!(edge_value & GRAPH_EXTRA_EDGES_NEEDED)) {
 432                 pptr = insert_parent_or_die(r, g, edge_value, pptr);
 433                 return 1;
 434         }
 435
 436         parent_data_ptr = (uint32_t*)(g->chunk_extra_edges +
 437                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 438         do {
 439                 edge_value = get_be32(parent_data_ptr);
 440                 pptr = insert_parent_or_die(r, g,
 441                                             edge_value & GRAPH_EDGE_LAST_MASK,
 442                                             pptr);
 443                 parent_data_ptr++;
 444         } while (!(edge_value & GRAPH_LAST_EDGE));
 445
 446         return 1;
 447 }
 448
 449 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 450 {
 451         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 452                 *pos = item->graph_pos;
 453                 return 1;
 454         } else {
 455                 return bsearch_graph(g, &(item->object.oid), pos);
 456         }
 457 }
 458
 459 static int parse_commit_in_graph_one(struct repository *r,
 460                                      struct commit_graph *g,
 461                                      struct commit *item)
 462 {
 463         uint32_t pos;
 464
 465         if (item->object.parsed)
 466                 return 1;
 467
 468         if (find_commit_in_graph(item, g, &pos))
 469                 return fill_commit_in_graph(r, item, g, pos);
 470
 471         return 0;
 472 }
 473
 474 int parse_commit_in_graph(struct repository *r, struct commit *item)
 475 {
 476         if (!prepare_commit_graph(r))
 477                 return 0;
 478         return parse_commit_in_graph_one(r, r->objects->commit_graph, item);
 479 }
 480
 481 void load_commit_graph_info(struct repository *r, struct commit *item)
 482 {
 483         uint32_t pos;
 484         if (!prepare_commit_graph(r))
 485                 return;
 486         if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
 487                 fill_commit_graph_info(item, r->objects->commit_graph, pos);
 488 }
 489
 490 static struct tree *load_tree_for_commit(struct repository *r,
 491                                          struct commit_graph *g,
 492                                          struct commit *c)
 493 {
 494         struct object_id oid;
 495         const unsigned char *commit_data = g->chunk_commit_data +
 496                                            GRAPH_DATA_WIDTH * (c->graph_pos);
 497
 498         hashcpy(oid.hash, commit_data);
 499         c->maybe_tree = lookup_tree(r, &oid);
 500
 501         return c->maybe_tree;
 502 }
 503
 504 static struct tree *get_commit_tree_in_graph_one(struct repository *r,
 505                                                  struct commit_graph *g,
 506                                                  const struct commit *c)
 507 {
 508         if (c->maybe_tree)
 509                 return c->maybe_tree;
 510         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 511                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 512
 513         return load_tree_for_commit(r, g, (struct commit *)c);
 514 }
 515
 516 struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
 517 {
 518         return get_commit_tree_in_graph_one(r, r->objects->commit_graph, c);
 519 }
 520
 521 struct packed_commit_list {
 522         struct commit **list;
 523         int nr;
 524         int alloc;
 525 };
 526
 527 struct packed_oid_list {
 528         struct object_id *list;
 529         int nr;
 530         int alloc;
 531 };
 532
 533 struct write_commit_graph_context {
 534         struct repository *r;
 535         const char *obj_dir;
 536         char *graph_name;
 537         struct packed_oid_list oids;
 538         struct packed_commit_list commits;
 539         int num_extra_edges;
 540         unsigned long approx_nr_objects;
 541         struct progress *progress;
 542         int progress_done;
 543         uint64_t progress_cnt;
 544         unsigned append:1,
 545                  report_progress:1;
 546 };
 547
 548 static void write_graph_chunk_fanout(struct hashfile *f,
 549                                      struct write_commit_graph_context *ctx)
 550 {
 551         int i, count = 0;
 552         struct commit **list = ctx->commits.list;
 553
 554         /*
 555          * Write the first-level table (the list is sorted,
 556          * but we use a 256-entry lookup to be able to avoid
 557          * having to do eight extra binary search iterations).
 558          */
 559         for (i = 0; i < 256; i++) {
 560                 while (count < ctx->commits.nr) {
 561                         if ((*list)->object.oid.hash[0] != i)
 562                                 break;
 563                         display_progress(ctx->progress, ++ctx->progress_cnt);
 564                         count++;
 565                         list++;
 566                 }
 567
 568                 hashwrite_be32(f, count);
 569         }
 570 }
 571
 572 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 573                                    struct write_commit_graph_context *ctx)
 574 {
 575         struct commit **list = ctx->commits.list;
 576         int count;
 577         for (count = 0; count < ctx->commits.nr; count++, list++) {
 578                 display_progress(ctx->progress, ++ctx->progress_cnt);
 579                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 580         }
 581 }
 582
 583 static const unsigned char *commit_to_sha1(size_t index, void *table)
 584 {
 585         struct commit **commits = table;
 586         return commits[index]->object.oid.hash;
 587 }
 588
 589 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 590                                    struct write_commit_graph_context *ctx)
 591 {
 592         struct commit **list = ctx->commits.list;
 593         struct commit **last = ctx->commits.list + ctx->commits.nr;
 594         uint32_t num_extra_edges = 0;
 595
 596         while (list < last) {
 597                 struct commit_list *parent;
 598                 int edge_value;
 599                 uint32_t packedDate[2];
 600                 display_progress(ctx->progress, ++ctx->progress_cnt);
 601
 602                 parse_commit_no_graph(*list);
 603                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 604
 605                 parent = (*list)->parents;
 606
 607                 if (!parent)
 608                         edge_value = GRAPH_PARENT_NONE;
 609                 else {
 610                         edge_value = sha1_pos(parent->item->object.oid.hash,
 611                                               ctx->commits.list,
 612                                               ctx->commits.nr,
 613                                               commit_to_sha1);
 614
 615                         if (edge_value < 0)
 616                                 BUG("missing parent %s for commit %s",
 617                                     oid_to_hex(&parent->item->object.oid),
 618                                     oid_to_hex(&(*list)->object.oid));
 619                 }
 620
 621                 hashwrite_be32(f, edge_value);
 622
 623                 if (parent)
 624                         parent = parent->next;
 625
 626                 if (!parent)
 627                         edge_value = GRAPH_PARENT_NONE;
 628                 else if (parent->next)
 629                         edge_value = GRAPH_EXTRA_EDGES_NEEDED | num_extra_edges;
 630                 else {
 631                         edge_value = sha1_pos(parent->item->object.oid.hash,
 632                                               ctx->commits.list,
 633                                               ctx->commits.nr,
 634                                               commit_to_sha1);
 635                         if (edge_value < 0)
 636                                 BUG("missing parent %s for commit %s",
 637                                     oid_to_hex(&parent->item->object.oid),
 638                                     oid_to_hex(&(*list)->object.oid));
 639                 }
 640
 641                 hashwrite_be32(f, edge_value);
 642
 643                 if (edge_value & GRAPH_EXTRA_EDGES_NEEDED) {
 644                         do {
 645                                 num_extra_edges++;
 646                                 parent = parent->next;
 647                         } while (parent);
 648                 }
 649
 650                 if (sizeof((*list)->date) > 4)
 651                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 652                 else
 653                         packedDate[0] = 0;
 654
 655                 packedDate[0] |= htonl((*list)->generation << 2);
 656
 657                 packedDate[1] = htonl((*list)->date);
 658                 hashwrite(f, packedDate, 8);
 659
 660                 list++;
 661         }
 662 }
 663
 664 static void write_graph_chunk_extra_edges(struct hashfile *f,
 665                                           struct write_commit_graph_context *ctx)
 666 {
 667         struct commit **list = ctx->commits.list;
 668         struct commit **last = ctx->commits.list + ctx->commits.nr;
 669         struct commit_list *parent;
 670
 671         while (list < last) {
 672                 int num_parents = 0;
 673
 674                 display_progress(ctx->progress, ++ctx->progress_cnt);
 675
 676                 for (parent = (*list)->parents; num_parents < 3 && parent;
 677                      parent = parent->next)
 678                         num_parents++;
 679
 680                 if (num_parents <= 2) {
 681                         list++;
 682                         continue;
 683                 }
 684
 685                 /* Since num_parents > 2, this initializer is safe. */
 686                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 687                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 688                                                   ctx->commits.list,
 689                                                   ctx->commits.nr,
 690                                                   commit_to_sha1);
 691
 692                         if (edge_value < 0)
 693                                 BUG("missing parent %s for commit %s",
 694                                     oid_to_hex(&parent->item->object.oid),
 695                                     oid_to_hex(&(*list)->object.oid));
 696                         else if (!parent->next)
 697                                 edge_value |= GRAPH_LAST_EDGE;
 698
 699                         hashwrite_be32(f, edge_value);
 700                 }
 701
 702                 list++;
 703         }
 704 }
 705
 706 static int commit_compare(const void *_a, const void *_b)
 707 {
 708         const struct object_id *a = (const struct object_id *)_a;
 709         const struct object_id *b = (const struct object_id *)_b;
 710         return oidcmp(a, b);
 711 }
 712
 713 static int add_packed_commits(const struct object_id *oid,
 714                               struct packed_git *pack,
 715                               uint32_t pos,
 716                               void *data)
 717 {
 718         struct write_commit_graph_context *ctx = (struct write_commit_graph_context*)data;
 719         enum object_type type;
 720         off_t offset = nth_packed_object_offset(pack, pos);
 721         struct object_info oi = OBJECT_INFO_INIT;
 722
 723         if (ctx->progress)
 724                 display_progress(ctx->progress, ++ctx->progress_done);
 725
 726         oi.typep = &type;
 727         if (packed_object_info(ctx->r, pack, offset, &oi) < 0)
 728                 die(_("unable to get type of object %s"), oid_to_hex(oid));
 729
 730         if (type != OBJ_COMMIT)
 731                 return 0;
 732
 733         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
 734         oidcpy(&(ctx->oids.list[ctx->oids.nr]), oid);
 735         ctx->oids.nr++;
 736
 737         return 0;
 738 }
 739
 740 static void add_missing_parents(struct write_commit_graph_context *ctx, struct commit *commit)
 741 {
 742         struct commit_list *parent;
 743         for (parent = commit->parents; parent; parent = parent->next) {
 744                 if (!(parent->item->object.flags & UNINTERESTING)) {
 745                         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
 746                         oidcpy(&ctx->oids.list[ctx->oids.nr], &(parent->item->object.oid));
 747                         ctx->oids.nr++;
 748                         parent->item->object.flags |= UNINTERESTING;
 749                 }
 750         }
 751 }
 752
 753 static void close_reachable(struct write_commit_graph_context *ctx)
 754 {
 755         int i;
 756         struct commit *commit;
 757
 758         if (ctx->report_progress)
 759                 ctx->progress = start_delayed_progress(
 760                                         _("Loading known commits in commit graph"),
 761                                         ctx->oids.nr);
 762         for (i = 0; i < ctx->oids.nr; i++) {
 763                 display_progress(ctx->progress, i + 1);
 764                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
 765                 if (commit)
 766                         commit->object.flags |= UNINTERESTING;
 767         }
 768         stop_progress(&ctx->progress);
 769
 770         /*
 771          * As this loop runs, ctx->oids.nr may grow, but not more
 772          * than the number of missing commits in the reachable
 773          * closure.
 774          */
 775         if (ctx->report_progress)
 776                 ctx->progress = start_delayed_progress(
 777                                         _("Expanding reachable commits in commit graph"),
 778                                         ctx->oids.nr);
 779         for (i = 0; i < ctx->oids.nr; i++) {
 780                 display_progress(ctx->progress, i + 1);
 781                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
 782
 783                 if (commit && !parse_commit_no_graph(commit))
 784                         add_missing_parents(ctx, commit);
 785         }
 786         stop_progress(&ctx->progress);
 787
 788         if (ctx->report_progress)
 789                 ctx->progress = start_delayed_progress(
 790                                         _("Clearing commit marks in commit graph"),
 791                                         ctx->oids.nr);
 792         for (i = 0; i < ctx->oids.nr; i++) {
 793                 display_progress(ctx->progress, i + 1);
 794                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
 795
 796                 if (commit)
 797                         commit->object.flags &= ~UNINTERESTING;
 798         }
 799         stop_progress(&ctx->progress);
 800 }
 801
 802 static void compute_generation_numbers(struct write_commit_graph_context *ctx)
 803 {
 804         int i;
 805         struct commit_list *list = NULL;
 806
 807         if (ctx->report_progress)
 808                 ctx->progress = start_progress(
 809                                         _("Computing commit graph generation numbers"),
 810                                         ctx->commits.nr);
 811         for (i = 0; i < ctx->commits.nr; i++) {
 812                 display_progress(ctx->progress, i + 1);
 813                 if (ctx->commits.list[i]->generation != GENERATION_NUMBER_INFINITY &&
 814                     ctx->commits.list[i]->generation != GENERATION_NUMBER_ZERO)
 815                         continue;
 816
 817                 commit_list_insert(ctx->commits.list[i], &list);
 818                 while (list) {
 819                         struct commit *current = list->item;
 820                         struct commit_list *parent;
 821                         int all_parents_computed = 1;
 822                         uint32_t max_generation = 0;
 823
 824                         for (parent = current->parents; parent; parent = parent->next) {
 825                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 826                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 827                                         all_parents_computed = 0;
 828                                         commit_list_insert(parent->item, &list);
 829                                         break;
 830                                 } else if (parent->item->generation > max_generation) {
 831                                         max_generation = parent->item->generation;
 832                                 }
 833                         }
 834
 835                         if (all_parents_computed) {
 836                                 current->generation = max_generation + 1;
 837                                 pop_commit(&list);
 838
 839                                 if (current->generation > GENERATION_NUMBER_MAX)
 840                                         current->generation = GENERATION_NUMBER_MAX;
 841                         }
 842                 }
 843         }
 844         stop_progress(&ctx->progress);
 845 }
 846
 847 static int add_ref_to_list(const char *refname,
 848                            const struct object_id *oid,
 849                            int flags, void *cb_data)
 850 {
 851         struct string_list *list = (struct string_list *)cb_data;
 852
 853         string_list_append(list, oid_to_hex(oid));
 854         return 0;
 855 }
 856
 857 int write_commit_graph_reachable(const char *obj_dir, unsigned int flags)
 858 {
 859         struct string_list list = STRING_LIST_INIT_DUP;
 860         int result;
 861
 862         for_each_ref(add_ref_to_list, &list);
 863         result = write_commit_graph(obj_dir, NULL, &list,
 864                                     flags);
 865
 866         string_list_clear(&list, 0);
 867         return result;
 868 }
 869
 870 static int fill_oids_from_packs(struct write_commit_graph_context *ctx,
 871                                 struct string_list *pack_indexes)
 872 {
 873         uint32_t i;
 874         struct strbuf progress_title = STRBUF_INIT;
 875         struct strbuf packname = STRBUF_INIT;
 876         int dirlen;
 877
 878         strbuf_addf(&packname, "%s/pack/", ctx->obj_dir);
 879         dirlen = packname.len;
 880         if (ctx->report_progress) {
 881                 strbuf_addf(&progress_title,
 882                             Q_("Finding commits for commit graph in %d pack",
 883                                "Finding commits for commit graph in %d packs",
 884                                pack_indexes->nr),
 885                             pack_indexes->nr);
 886                 ctx->progress = start_delayed_progress(progress_title.buf, 0);
 887                 ctx->progress_done = 0;
 888         }
 889         for (i = 0; i < pack_indexes->nr; i++) {
 890                 struct packed_git *p;
 891                 strbuf_setlen(&packname, dirlen);
 892                 strbuf_addstr(&packname, pack_indexes->items[i].string);
 893                 p = add_packed_git(packname.buf, packname.len, 1);
 894                 if (!p) {
 895                         error(_("error adding pack %s"), packname.buf);
 896                         return -1;
 897                 }
 898                 if (open_pack_index(p)) {
 899                         error(_("error opening index for %s"), packname.buf);
 900                         return -1;
 901                 }
 902                 for_each_object_in_pack(p, add_packed_commits, ctx,
 903                                         FOR_EACH_OBJECT_PACK_ORDER);
 904                 close_pack(p);
 905                 free(p);
 906         }
 907
 908         stop_progress(&ctx->progress);
 909         strbuf_reset(&progress_title);
 910         strbuf_release(&packname);
 911
 912         return 0;
 913 }
 914
 915 static void fill_oids_from_commit_hex(struct write_commit_graph_context *ctx,
 916                                       struct string_list *commit_hex)
 917 {
 918         uint32_t i;
 919         struct strbuf progress_title = STRBUF_INIT;
 920
 921         if (ctx->report_progress) {
 922                 strbuf_addf(&progress_title,
 923                             Q_("Finding commits for commit graph from %d ref",
 924                                "Finding commits for commit graph from %d refs",
 925                                commit_hex->nr),
 926                             commit_hex->nr);
 927                 ctx->progress = start_delayed_progress(
 928                                         progress_title.buf,
 929                                         commit_hex->nr);
 930         }
 931         for (i = 0; i < commit_hex->nr; i++) {
 932                 const char *end;
 933                 struct object_id oid;
 934                 struct commit *result;
 935
 936                 display_progress(ctx->progress, i + 1);
 937                 if (commit_hex->items[i].string &&
 938                     parse_oid_hex(commit_hex->items[i].string, &oid, &end))
 939                         continue;
 940
 941                 result = lookup_commit_reference_gently(ctx->r, &oid, 1);
 942
 943                 if (result) {
 944                         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
 945                         oidcpy(&ctx->oids.list[ctx->oids.nr], &(result->object.oid));
 946                         ctx->oids.nr++;
 947                 }
 948         }
 949         stop_progress(&ctx->progress);
 950         strbuf_release(&progress_title);
 951 }
 952
 953 static void fill_oids_from_all_packs(struct write_commit_graph_context *ctx)
 954 {
 955         if (ctx->report_progress)
 956                 ctx->progress = start_delayed_progress(
 957                         _("Finding commits for commit graph among packed objects"),
 958                         ctx->approx_nr_objects);
 959         for_each_packed_object(add_packed_commits, ctx,
 960                                FOR_EACH_OBJECT_PACK_ORDER);
 961         if (ctx->progress_done < ctx->approx_nr_objects)
 962                 display_progress(ctx->progress, ctx->approx_nr_objects);
 963         stop_progress(&ctx->progress);
 964 }
 965
 966 static uint32_t count_distinct_commits(struct write_commit_graph_context *ctx)
 967 {
 968         uint32_t i, count_distinct = 1;
 969
 970         if (ctx->report_progress)
 971                 ctx->progress = start_delayed_progress(
 972                         _("Counting distinct commits in commit graph"),
 973                         ctx->oids.nr);
 974         display_progress(ctx->progress, 0); /* TODO: Measure QSORT() progress */
 975         QSORT(ctx->oids.list, ctx->oids.nr, commit_compare);
 976
 977         for (i = 1; i < ctx->oids.nr; i++) {
 978                 display_progress(ctx->progress, i + 1);
 979                 if (!oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i]))
 980                         count_distinct++;
 981         }
 982         stop_progress(&ctx->progress);
 983
 984         return count_distinct;
 985 }
 986
 987 static void copy_oids_to_commits(struct write_commit_graph_context *ctx)
 988 {
 989         uint32_t i;
 990         struct commit_list *parent;
 991
 992         ctx->num_extra_edges = 0;
 993         if (ctx->report_progress)
 994                 ctx->progress = start_delayed_progress(
 995                         _("Finding extra edges in commit graph"),
 996                         ctx->oids.nr);
 997         for (i = 0; i < ctx->oids.nr; i++) {
 998                 int num_parents = 0;
 999                 display_progress(ctx->progress, i + 1);
1000                 if (i > 0 && oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i]))
1001                         continue;
1002
1003                 ctx->commits.list[ctx->commits.nr] = lookup_commit(ctx->r, &ctx->oids.list[i]);
1004                 parse_commit_no_graph(ctx->commits.list[ctx->commits.nr]);
1005
1006                 for (parent = ctx->commits.list[ctx->commits.nr]->parents;
1007                      parent; parent = parent->next)
1008                         num_parents++;
1009
1010                 if (num_parents > 2)
1011                         ctx->num_extra_edges += num_parents - 1;
1012
1013                 ctx->commits.nr++;
1014         }
1015         stop_progress(&ctx->progress);
1016 }
1017
1018 static int write_commit_graph_file(struct write_commit_graph_context *ctx)
1019 {
1020         uint32_t i;
1021         struct hashfile *f;
1022         struct lock_file lk = LOCK_INIT;
1023         uint32_t chunk_ids[5];
1024         uint64_t chunk_offsets[5];
1025         const unsigned hashsz = the_hash_algo->rawsz;
1026         struct strbuf progress_title = STRBUF_INIT;
1027         int num_chunks = ctx->num_extra_edges ? 4 : 3;
1028
1029         ctx->graph_name = get_commit_graph_filename(ctx->obj_dir);
1030         if (safe_create_leading_directories(ctx->graph_name)) {
1031                 UNLEAK(ctx->graph_name);
1032                 error(_("unable to create leading directories of %s"),
1033                         ctx->graph_name);
1034                 return -1;
1035         }
1036
1037         hold_lock_file_for_update(&lk, ctx->graph_name, LOCK_DIE_ON_ERROR);
1038         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
1039
1040         hashwrite_be32(f, GRAPH_SIGNATURE);
1041
1042         hashwrite_u8(f, GRAPH_VERSION);
1043         hashwrite_u8(f, oid_version());
1044         hashwrite_u8(f, num_chunks);
1045         hashwrite_u8(f, 0); /* unused padding byte */
1046
1047         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
1048         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
1049         chunk_ids[2] = GRAPH_CHUNKID_DATA;
1050         if (ctx->num_extra_edges)
1051                 chunk_ids[3] = GRAPH_CHUNKID_EXTRAEDGES;
1052         else
1053                 chunk_ids[3] = 0;
1054         chunk_ids[4] = 0;
1055
1056         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
1057         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
1058         chunk_offsets[2] = chunk_offsets[1] + hashsz * ctx->commits.nr;
1059         chunk_offsets[3] = chunk_offsets[2] + (hashsz + 16) * ctx->commits.nr;
1060         chunk_offsets[4] = chunk_offsets[3] + 4 * ctx->num_extra_edges;
1061
1062         for (i = 0; i <= num_chunks; i++) {
1063                 uint32_t chunk_write[3];
1064
1065                 chunk_write[0] = htonl(chunk_ids[i]);
1066                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
1067                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
1068                 hashwrite(f, chunk_write, 12);
1069         }
1070
1071         if (ctx->report_progress) {
1072                 strbuf_addf(&progress_title,
1073                             Q_("Writing out commit graph in %d pass",
1074                                "Writing out commit graph in %d passes",
1075                                num_chunks),
1076                             num_chunks);
1077                 ctx->progress = start_delayed_progress(
1078                         progress_title.buf,
1079                         num_chunks * ctx->commits.nr);
1080         }
1081         write_graph_chunk_fanout(f, ctx);
1082         write_graph_chunk_oids(f, hashsz, ctx);
1083         write_graph_chunk_data(f, hashsz, ctx);
1084         if (ctx->num_extra_edges)
1085                 write_graph_chunk_extra_edges(f, ctx);
1086         stop_progress(&ctx->progress);
1087         strbuf_release(&progress_title);
1088
1089         close_commit_graph(ctx->r->objects);
1090         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
1091         commit_lock_file(&lk);
1092
1093         return 0;
1094 }
1095
1096 int write_commit_graph(const char *obj_dir,
1097                        struct string_list *pack_indexes,
1098                        struct string_list *commit_hex,
1099                        unsigned int flags)
1100 {
1101         struct write_commit_graph_context *ctx;
1102         uint32_t i, count_distinct = 0;
1103         int res = 0;
1104
1105         if (!commit_graph_compatible(the_repository))
1106                 return 0;
1107
1108         ctx = xcalloc(1, sizeof(struct write_commit_graph_context));
1109         ctx->r = the_repository;
1110         ctx->obj_dir = obj_dir;
1111         ctx->append = flags & COMMIT_GRAPH_APPEND ? 1 : 0;
1112         ctx->report_progress = flags & COMMIT_GRAPH_PROGRESS ? 1 : 0;
1113
1114         ctx->approx_nr_objects = approximate_object_count();
1115         ctx->oids.alloc = ctx->approx_nr_objects / 32;
1116
1117         if (ctx->append) {
1118                 prepare_commit_graph_one(ctx->r, ctx->obj_dir);
1119                 if (ctx->r->objects->commit_graph)
1120                         ctx->oids.alloc += ctx->r->objects->commit_graph->num_commits;
1121         }
1122
1123         if (ctx->oids.alloc < 1024)
1124                 ctx->oids.alloc = 1024;
1125         ALLOC_ARRAY(ctx->oids.list, ctx->oids.alloc);
1126
1127         if (ctx->append && ctx->r->objects->commit_graph) {
1128                 struct commit_graph *g = ctx->r->objects->commit_graph;
1129                 for (i = 0; i < g->num_commits; i++) {
1130                         const unsigned char *hash = g->chunk_oid_lookup + g->hash_len * i;
1131                         hashcpy(ctx->oids.list[ctx->oids.nr++].hash, hash);
1132                 }
1133         }
1134
1135         if (pack_indexes) {
1136                 if ((res = fill_oids_from_packs(ctx, pack_indexes)))
1137                         goto cleanup;
1138         }
1139
1140         if (commit_hex)
1141                 fill_oids_from_commit_hex(ctx, commit_hex);
1142
1143         if (!pack_indexes && !commit_hex)
1144                 fill_oids_from_all_packs(ctx);
1145
1146         close_reachable(ctx);
1147
1148         count_distinct = count_distinct_commits(ctx);
1149
1150         if (count_distinct >= GRAPH_EDGE_LAST_MASK) {
1151                 error(_("the commit graph format cannot write %d commits"), count_distinct);
1152                 res = -1;
1153                 goto cleanup;
1154         }
1155
1156         ctx->commits.alloc = count_distinct;
1157         ALLOC_ARRAY(ctx->commits.list, ctx->commits.alloc);
1158
1159         copy_oids_to_commits(ctx);
1160
1161         if (ctx->commits.nr >= GRAPH_EDGE_LAST_MASK) {
1162                 error(_("too many commits to write graph"));
1163                 res = -1;
1164                 goto cleanup;
1165         }
1166
1167         compute_generation_numbers(ctx);
1168
1169         res = write_commit_graph_file(ctx);
1170
1171 cleanup:
1172         free(ctx->graph_name);
1173         free(ctx->commits.list);
1174         free(ctx->oids.list);
1175         free(ctx);
1176
1177         return res;
1178 }
1179
1180 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
1181 static int verify_commit_graph_error;
1182
1183 static void graph_report(const char *fmt, ...)
1184 {
1185         va_list ap;
1186
1187         verify_commit_graph_error = 1;
1188         va_start(ap, fmt);
1189         vfprintf(stderr, fmt, ap);
1190         fprintf(stderr, "\n");
1191         va_end(ap);
1192 }
1193
1194 #define GENERATION_ZERO_EXISTS 1
1195 #define GENERATION_NUMBER_EXISTS 2
1196
1197 int verify_commit_graph(struct repository *r, struct commit_graph *g)
1198 {
1199         uint32_t i, cur_fanout_pos = 0;
1200         struct object_id prev_oid, cur_oid, checksum;
1201         int generation_zero = 0;
1202         struct hashfile *f;
1203         int devnull;
1204         struct progress *progress = NULL;
1205
1206         if (!g) {
1207                 graph_report("no commit-graph file loaded");
1208                 return 1;
1209         }
1210
1211         verify_commit_graph_error = verify_commit_graph_lite(g);
1212         if (verify_commit_graph_error)
1213                 return verify_commit_graph_error;
1214
1215         devnull = open("/dev/null", O_WRONLY);
1216         f = hashfd(devnull, NULL);
1217         hashwrite(f, g->data, g->data_len - g->hash_len);
1218         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
1219         if (!hasheq(checksum.hash, g->data + g->data_len - g->hash_len)) {
1220                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
1221                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
1222         }
1223
1224         for (i = 0; i < g->num_commits; i++) {
1225                 struct commit *graph_commit;
1226
1227                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1228
1229                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
1230                         graph_report(_("commit-graph has incorrect OID order: %s then %s"),
1231                                      oid_to_hex(&prev_oid),
1232                                      oid_to_hex(&cur_oid));
1233
1234                 oidcpy(&prev_oid, &cur_oid);
1235
1236                 while (cur_oid.hash[0] > cur_fanout_pos) {
1237                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1238
1239                         if (i != fanout_value)
1240                                 graph_report(_("commit-graph has incorrect fanout value: fanout[%d] = %u != %u"),
1241                                              cur_fanout_pos, fanout_value, i);
1242                         cur_fanout_pos++;
1243                 }
1244
1245                 graph_commit = lookup_commit(r, &cur_oid);
1246                 if (!parse_commit_in_graph_one(r, g, graph_commit))
1247                         graph_report(_("failed to parse commit %s from commit-graph"),
1248                                      oid_to_hex(&cur_oid));
1249         }
1250
1251         while (cur_fanout_pos < 256) {
1252                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1253
1254                 if (g->num_commits != fanout_value)
1255                         graph_report(_("commit-graph has incorrect fanout value: fanout[%d] = %u != %u"),
1256                                      cur_fanout_pos, fanout_value, i);
1257
1258                 cur_fanout_pos++;
1259         }
1260
1261         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
1262                 return verify_commit_graph_error;
1263
1264         progress = start_progress(_("Verifying commits in commit graph"),
1265                                   g->num_commits);
1266         for (i = 0; i < g->num_commits; i++) {
1267                 struct commit *graph_commit, *odb_commit;
1268                 struct commit_list *graph_parents, *odb_parents;
1269                 uint32_t max_generation = 0;
1270
1271                 display_progress(progress, i + 1);
1272                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1273
1274                 graph_commit = lookup_commit(r, &cur_oid);
1275                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
1276                 if (parse_commit_internal(odb_commit, 0, 0)) {
1277                         graph_report(_("failed to parse commit %s from object database for commit-graph"),
1278                                      oid_to_hex(&cur_oid));
1279                         continue;
1280                 }
1281
1282                 if (!oideq(&get_commit_tree_in_graph_one(r, g, graph_commit)->object.oid,
1283                            get_commit_tree_oid(odb_commit)))
1284                         graph_report(_("root tree OID for commit %s in commit-graph is %s != %s"),
1285                                      oid_to_hex(&cur_oid),
1286                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
1287                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
1288
1289                 graph_parents = graph_commit->parents;
1290                 odb_parents = odb_commit->parents;
1291
1292                 while (graph_parents) {
1293                         if (odb_parents == NULL) {
1294                                 graph_report(_("commit-graph parent list for commit %s is too long"),
1295                                              oid_to_hex(&cur_oid));
1296                                 break;
1297                         }
1298
1299                         if (!oideq(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
1300                                 graph_report(_("commit-graph parent for %s is %s != %s"),
1301                                              oid_to_hex(&cur_oid),
1302                                              oid_to_hex(&graph_parents->item->object.oid),
1303                                              oid_to_hex(&odb_parents->item->object.oid));
1304
1305                         if (graph_parents->item->generation > max_generation)
1306                                 max_generation = graph_parents->item->generation;
1307
1308                         graph_parents = graph_parents->next;
1309                         odb_parents = odb_parents->next;
1310                 }
1311
1312                 if (odb_parents != NULL)
1313                         graph_report(_("commit-graph parent list for commit %s terminates early"),
1314                                      oid_to_hex(&cur_oid));
1315
1316                 if (!graph_commit->generation) {
1317                         if (generation_zero == GENERATION_NUMBER_EXISTS)
1318                                 graph_report(_("commit-graph has generation number zero for commit %s, but non-zero elsewhere"),
1319                                              oid_to_hex(&cur_oid));
1320                         generation_zero = GENERATION_ZERO_EXISTS;
1321                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1322                         graph_report(_("commit-graph has non-zero generation number for commit %s, but zero elsewhere"),
1323                                      oid_to_hex(&cur_oid));
1324
1325                 if (generation_zero == GENERATION_ZERO_EXISTS)
1326                         continue;
1327
1328                 /*
1329                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1330                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1331                  * extra logic in the following condition.
1332                  */
1333                 if (max_generation == GENERATION_NUMBER_MAX)
1334                         max_generation--;
1335
1336                 if (graph_commit->generation != max_generation + 1)
1337                         graph_report(_("commit-graph generation for commit %s is %u != %u"),
1338                                      oid_to_hex(&cur_oid),
1339                                      graph_commit->generation,
1340                                      max_generation + 1);
1341
1342                 if (graph_commit->date != odb_commit->date)
1343                         graph_report(_("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime),
1344                                      oid_to_hex(&cur_oid),
1345                                      graph_commit->date,
1346                                      odb_commit->date);
1347         }
1348         stop_progress(&progress);
1349
1350         return verify_commit_graph_error;
1351 }
1352
1353 void free_commit_graph(struct commit_graph *g)
1354 {
1355         if (!g)
1356                 return;
1357         if (g->graph_fd >= 0) {
1358                 munmap((void *)g->data, g->data_len);
1359                 g->data = NULL;
1360                 close(g->graph_fd);
1361         }
1362         free(g);
1363 }