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