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 #define GRAPH_CHUNKID_BASE 0x42415345 /* "BASE" */
  26
  27 #define GRAPH_DATA_WIDTH (the_hash_algo->rawsz + 16)
  28
  29 #define GRAPH_VERSION_1 0x1
  30 #define GRAPH_VERSION GRAPH_VERSION_1
  31
  32 #define GRAPH_EXTRA_EDGES_NEEDED 0x80000000
  33 #define GRAPH_EDGE_LAST_MASK 0x7fffffff
  34 #define GRAPH_PARENT_NONE 0x70000000
  35
  36 #define GRAPH_LAST_EDGE 0x80000000
  37
  38 #define GRAPH_HEADER_SIZE 8
  39 #define GRAPH_FANOUT_SIZE (4 * 256)
  40 #define GRAPH_CHUNKLOOKUP_WIDTH 12
  41 #define GRAPH_MIN_SIZE (GRAPH_HEADER_SIZE + 4 * GRAPH_CHUNKLOOKUP_WIDTH \
  42                         + GRAPH_FANOUT_SIZE + the_hash_algo->rawsz)
  43
  44 /* Remember to update object flag allocation in object.h */
  45 #define REACHABLE       (1u<<15)
  46
  47 char *get_commit_graph_filename(struct object_directory *odb)
  48 {
  49         return xstrfmt("%s/info/commit-graph", odb->path);
  50 }
  51
  52 static char *get_split_graph_filename(struct object_directory *odb,
  53                                       const char *oid_hex)
  54 {
  55         return xstrfmt("%s/info/commit-graphs/graph-%s.graph", odb->path,
  56                        oid_hex);
  57 }
  58
  59 static char *get_chain_filename(struct object_directory *odb)
  60 {
  61         return xstrfmt("%s/info/commit-graphs/commit-graph-chain", odb->path);
  62 }
  63
  64 static uint8_t oid_version(void)
  65 {
  66         return 1;
  67 }
  68
  69 static struct commit_graph *alloc_commit_graph(void)
  70 {
  71         struct commit_graph *g = xcalloc(1, sizeof(*g));
  72
  73         return g;
  74 }
  75
  76 extern int read_replace_refs;
  77
  78 static int commit_graph_compatible(struct repository *r)
  79 {
  80         if (!r->gitdir)
  81                 return 0;
  82
  83         if (read_replace_refs) {
  84                 prepare_replace_object(r);
  85                 if (hashmap_get_size(&r->objects->replace_map->map))
  86                         return 0;
  87         }
  88
  89         prepare_commit_graft(r);
  90         if (r->parsed_objects && r->parsed_objects->grafts_nr)
  91                 return 0;
  92         if (is_repository_shallow(r))
  93                 return 0;
  94
  95         return 1;
  96 }
  97
  98 int open_commit_graph(const char *graph_file, int *fd, struct stat *st)
  99 {
 100         *fd = git_open(graph_file);
 101         if (*fd < 0)
 102                 return 0;
 103         if (fstat(*fd, st)) {
 104                 close(*fd);
 105                 return 0;
 106         }
 107         return 1;
 108 }
 109
 110 struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st,
 111                                                  struct object_directory *odb)
 112 {
 113         void *graph_map;
 114         size_t graph_size;
 115         struct commit_graph *ret;
 116
 117         graph_size = xsize_t(st->st_size);
 118
 119         if (graph_size < GRAPH_MIN_SIZE) {
 120                 close(fd);
 121                 error(_("commit-graph file is too small"));
 122                 return NULL;
 123         }
 124         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
 125         close(fd);
 126         ret = parse_commit_graph(graph_map, graph_size);
 127
 128         if (ret)
 129                 ret->odb = odb;
 130         else
 131                 munmap(graph_map, graph_size);
 132
 133         return ret;
 134 }
 135
 136 static int verify_commit_graph_lite(struct commit_graph *g)
 137 {
 138         /*
 139          * Basic validation shared between parse_commit_graph()
 140          * which'll be called every time the graph is used, and the
 141          * much more expensive verify_commit_graph() used by
 142          * "commit-graph verify".
 143          *
 144          * There should only be very basic checks here to ensure that
 145          * we don't e.g. segfault in fill_commit_in_graph(), but
 146          * because this is a very hot codepath nothing that e.g. loops
 147          * over g->num_commits, or runs a checksum on the commit-graph
 148          * itself.
 149          */
 150         if (!g->chunk_oid_fanout) {
 151                 error("commit-graph is missing the OID Fanout chunk");
 152                 return 1;
 153         }
 154         if (!g->chunk_oid_lookup) {
 155                 error("commit-graph is missing the OID Lookup chunk");
 156                 return 1;
 157         }
 158         if (!g->chunk_commit_data) {
 159                 error("commit-graph is missing the Commit Data chunk");
 160                 return 1;
 161         }
 162
 163         return 0;
 164 }
 165
 166 struct commit_graph *parse_commit_graph(void *graph_map, size_t graph_size)
 167 {
 168         const unsigned char *data, *chunk_lookup;
 169         uint32_t i;
 170         struct commit_graph *graph;
 171         uint64_t last_chunk_offset;
 172         uint32_t last_chunk_id;
 173         uint32_t graph_signature;
 174         unsigned char graph_version, hash_version;
 175
 176         if (!graph_map)
 177                 return NULL;
 178
 179         if (graph_size < GRAPH_MIN_SIZE)
 180                 return NULL;
 181
 182         data = (const unsigned char *)graph_map;
 183
 184         graph_signature = get_be32(data);
 185         if (graph_signature != GRAPH_SIGNATURE) {
 186                 error(_("commit-graph signature %X does not match signature %X"),
 187                       graph_signature, GRAPH_SIGNATURE);
 188                 return NULL;
 189         }
 190
 191         graph_version = *(unsigned char*)(data + 4);
 192         if (graph_version != GRAPH_VERSION) {
 193                 error(_("commit-graph version %X does not match version %X"),
 194                       graph_version, GRAPH_VERSION);
 195                 return NULL;
 196         }
 197
 198         hash_version = *(unsigned char*)(data + 5);
 199         if (hash_version != oid_version()) {
 200                 error(_("commit-graph hash version %X does not match version %X"),
 201                       hash_version, oid_version());
 202                 return NULL;
 203         }
 204
 205         graph = alloc_commit_graph();
 206
 207         graph->hash_len = the_hash_algo->rawsz;
 208         graph->num_chunks = *(unsigned char*)(data + 6);
 209         graph->data = graph_map;
 210         graph->data_len = graph_size;
 211
 212         last_chunk_id = 0;
 213         last_chunk_offset = 8;
 214         chunk_lookup = data + 8;
 215         for (i = 0; i < graph->num_chunks; i++) {
 216                 uint32_t chunk_id;
 217                 uint64_t chunk_offset;
 218                 int chunk_repeated = 0;
 219
 220                 if (data + graph_size - chunk_lookup <
 221                     GRAPH_CHUNKLOOKUP_WIDTH) {
 222                         error(_("commit-graph chunk lookup table entry missing; file may be incomplete"));
 223                         free(graph);
 224                         return NULL;
 225                 }
 226
 227                 chunk_id = get_be32(chunk_lookup + 0);
 228                 chunk_offset = get_be64(chunk_lookup + 4);
 229
 230                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 231
 232                 if (chunk_offset > graph_size - the_hash_algo->rawsz) {
 233                         error(_("commit-graph improper chunk offset %08x%08x"), (uint32_t)(chunk_offset >> 32),
 234                               (uint32_t)chunk_offset);
 235                         free(graph);
 236                         return NULL;
 237                 }
 238
 239                 switch (chunk_id) {
 240                 case GRAPH_CHUNKID_OIDFANOUT:
 241                         if (graph->chunk_oid_fanout)
 242                                 chunk_repeated = 1;
 243                         else
 244                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 245                         break;
 246
 247                 case GRAPH_CHUNKID_OIDLOOKUP:
 248                         if (graph->chunk_oid_lookup)
 249                                 chunk_repeated = 1;
 250                         else
 251                                 graph->chunk_oid_lookup = data + chunk_offset;
 252                         break;
 253
 254                 case GRAPH_CHUNKID_DATA:
 255                         if (graph->chunk_commit_data)
 256                                 chunk_repeated = 1;
 257                         else
 258                                 graph->chunk_commit_data = data + chunk_offset;
 259                         break;
 260
 261                 case GRAPH_CHUNKID_EXTRAEDGES:
 262                         if (graph->chunk_extra_edges)
 263                                 chunk_repeated = 1;
 264                         else
 265                                 graph->chunk_extra_edges = data + chunk_offset;
 266                         break;
 267
 268                 case GRAPH_CHUNKID_BASE:
 269                         if (graph->chunk_base_graphs)
 270                                 chunk_repeated = 1;
 271                         else
 272                                 graph->chunk_base_graphs = data + chunk_offset;
 273                 }
 274
 275                 if (chunk_repeated) {
 276                         error(_("commit-graph chunk id %08x appears multiple times"), chunk_id);
 277                         free(graph);
 278                         return NULL;
 279                 }
 280
 281                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 282                 {
 283                         graph->num_commits = (chunk_offset - last_chunk_offset)
 284                                              / graph->hash_len;
 285                 }
 286
 287                 last_chunk_id = chunk_id;
 288                 last_chunk_offset = chunk_offset;
 289         }
 290
 291         hashcpy(graph->oid.hash, graph->data + graph->data_len - graph->hash_len);
 292
 293         if (verify_commit_graph_lite(graph)) {
 294                 free(graph);
 295                 return NULL;
 296         }
 297
 298         return graph;
 299 }
 300
 301 static struct commit_graph *load_commit_graph_one(const char *graph_file,
 302                                                   struct object_directory *odb)
 303 {
 304
 305         struct stat st;
 306         int fd;
 307         struct commit_graph *g;
 308         int open_ok = open_commit_graph(graph_file, &fd, &st);
 309
 310         if (!open_ok)
 311                 return NULL;
 312
 313         g = load_commit_graph_one_fd_st(fd, &st, odb);
 314
 315         if (g)
 316                 g->filename = xstrdup(graph_file);
 317
 318         return g;
 319 }
 320
 321 static struct commit_graph *load_commit_graph_v1(struct repository *r,
 322                                                  struct object_directory *odb)
 323 {
 324         char *graph_name = get_commit_graph_filename(odb);
 325         struct commit_graph *g = load_commit_graph_one(graph_name, odb);
 326         free(graph_name);
 327
 328         return g;
 329 }
 330
 331 static int add_graph_to_chain(struct commit_graph *g,
 332                               struct commit_graph *chain,
 333                               struct object_id *oids,
 334                               int n)
 335 {
 336         struct commit_graph *cur_g = chain;
 337
 338         if (n && !g->chunk_base_graphs) {
 339                 warning(_("commit-graph has no base graphs chunk"));
 340                 return 0;
 341         }
 342
 343         while (n) {
 344                 n--;
 345
 346                 if (!cur_g ||
 347                     !oideq(&oids[n], &cur_g->oid) ||
 348                     !hasheq(oids[n].hash, g->chunk_base_graphs + g->hash_len * n)) {
 349                         warning(_("commit-graph chain does not match"));
 350                         return 0;
 351                 }
 352
 353                 cur_g = cur_g->base_graph;
 354         }
 355
 356         g->base_graph = chain;
 357
 358         if (chain)
 359                 g->num_commits_in_base = chain->num_commits + chain->num_commits_in_base;
 360
 361         return 1;
 362 }
 363
 364 static struct commit_graph *load_commit_graph_chain(struct repository *r,
 365                                                     struct object_directory *odb)
 366 {
 367         struct commit_graph *graph_chain = NULL;
 368         struct strbuf line = STRBUF_INIT;
 369         struct stat st;
 370         struct object_id *oids;
 371         int i = 0, valid = 1, count;
 372         char *chain_name = get_chain_filename(odb);
 373         FILE *fp;
 374         int stat_res;
 375
 376         fp = fopen(chain_name, "r");
 377         stat_res = stat(chain_name, &st);
 378         free(chain_name);
 379
 380         if (!fp ||
 381             stat_res ||
 382             st.st_size <= the_hash_algo->hexsz)
 383                 return NULL;
 384
 385         count = st.st_size / (the_hash_algo->hexsz + 1);
 386         oids = xcalloc(count, sizeof(struct object_id));
 387
 388         prepare_alt_odb(r);
 389
 390         for (i = 0; i < count; i++) {
 391                 struct object_directory *odb;
 392
 393                 if (strbuf_getline_lf(&line, fp) == EOF)
 394                         break;
 395
 396                 if (get_oid_hex(line.buf, &oids[i])) {
 397                         warning(_("invalid commit-graph chain: line '%s' not a hash"),
 398                                 line.buf);
 399                         valid = 0;
 400                         break;
 401                 }
 402
 403                 valid = 0;
 404                 for (odb = r->objects->odb; odb; odb = odb->next) {
 405                         char *graph_name = get_split_graph_filename(odb, line.buf);
 406                         struct commit_graph *g = load_commit_graph_one(graph_name, odb);
 407
 408                         free(graph_name);
 409
 410                         if (g) {
 411                                 if (add_graph_to_chain(g, graph_chain, oids, i)) {
 412                                         graph_chain = g;
 413                                         valid = 1;
 414                                 }
 415
 416                                 break;
 417                         }
 418                 }
 419
 420                 if (!valid) {
 421                         warning(_("unable to find all commit-graph files"));
 422                         break;
 423                 }
 424         }
 425
 426         free(oids);
 427         fclose(fp);
 428         strbuf_release(&line);
 429
 430         return graph_chain;
 431 }
 432
 433 struct commit_graph *read_commit_graph_one(struct repository *r,
 434                                            struct object_directory *odb)
 435 {
 436         struct commit_graph *g = load_commit_graph_v1(r, odb);
 437
 438         if (!g)
 439                 g = load_commit_graph_chain(r, odb);
 440
 441         return g;
 442 }
 443
 444 static void prepare_commit_graph_one(struct repository *r,
 445                                      struct object_directory *odb)
 446 {
 447
 448         if (r->objects->commit_graph)
 449                 return;
 450
 451         r->objects->commit_graph = read_commit_graph_one(r, odb);
 452 }
 453
 454 /*
 455  * Return 1 if commit_graph is non-NULL, and 0 otherwise.
 456  *
 457  * On the first invocation, this function attempts to load the commit
 458  * graph if the_repository is configured to have one.
 459  */
 460 static int prepare_commit_graph(struct repository *r)
 461 {
 462         struct object_directory *odb;
 463
 464         /*
 465          * This must come before the "already attempted?" check below, because
 466          * we want to disable even an already-loaded graph file.
 467          */
 468         if (r->commit_graph_disabled)
 469                 return 0;
 470
 471         if (r->objects->commit_graph_attempted)
 472                 return !!r->objects->commit_graph;
 473         r->objects->commit_graph_attempted = 1;
 474
 475         if (git_env_bool(GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD, 0))
 476                 die("dying as requested by the '%s' variable on commit-graph load!",
 477                     GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD);
 478
 479         prepare_repo_settings(r);
 480
 481         if (!git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
 482             r->settings.core_commit_graph != 1)
 483                 /*
 484                  * This repository is not configured to use commit graphs, so
 485                  * do not load one. (But report commit_graph_attempted anyway
 486                  * so that commit graph loading is not attempted again for this
 487                  * repository.)
 488                  */
 489                 return 0;
 490
 491         if (!commit_graph_compatible(r))
 492                 return 0;
 493
 494         prepare_alt_odb(r);
 495         for (odb = r->objects->odb;
 496              !r->objects->commit_graph && odb;
 497              odb = odb->next)
 498                 prepare_commit_graph_one(r, odb);
 499         return !!r->objects->commit_graph;
 500 }
 501
 502 int generation_numbers_enabled(struct repository *r)
 503 {
 504         uint32_t first_generation;
 505         struct commit_graph *g;
 506         if (!prepare_commit_graph(r))
 507                return 0;
 508
 509         g = r->objects->commit_graph;
 510
 511         if (!g->num_commits)
 512                 return 0;
 513
 514         first_generation = get_be32(g->chunk_commit_data +
 515                                     g->hash_len + 8) >> 2;
 516
 517         return !!first_generation;
 518 }
 519
 520 static void close_commit_graph_one(struct commit_graph *g)
 521 {
 522         if (!g)
 523                 return;
 524
 525         close_commit_graph_one(g->base_graph);
 526         free_commit_graph(g);
 527 }
 528
 529 void close_commit_graph(struct raw_object_store *o)
 530 {
 531         close_commit_graph_one(o->commit_graph);
 532         o->commit_graph = NULL;
 533 }
 534
 535 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 536 {
 537         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 538                             g->chunk_oid_lookup, g->hash_len, pos);
 539 }
 540
 541 static void load_oid_from_graph(struct commit_graph *g,
 542                                 uint32_t pos,
 543                                 struct object_id *oid)
 544 {
 545         uint32_t lex_index;
 546
 547         while (g && pos < g->num_commits_in_base)
 548                 g = g->base_graph;
 549
 550         if (!g)
 551                 BUG("NULL commit-graph");
 552
 553         if (pos >= g->num_commits + g->num_commits_in_base)
 554                 die(_("invalid commit position. commit-graph is likely corrupt"));
 555
 556         lex_index = pos - g->num_commits_in_base;
 557
 558         hashcpy(oid->hash, g->chunk_oid_lookup + g->hash_len * lex_index);
 559 }
 560
 561 static struct commit_list **insert_parent_or_die(struct repository *r,
 562                                                  struct commit_graph *g,
 563                                                  uint32_t pos,
 564                                                  struct commit_list **pptr)
 565 {
 566         struct commit *c;
 567         struct object_id oid;
 568
 569         if (pos >= g->num_commits + g->num_commits_in_base)
 570                 die("invalid parent position %"PRIu32, pos);
 571
 572         load_oid_from_graph(g, pos, &oid);
 573         c = lookup_commit(r, &oid);
 574         if (!c)
 575                 die(_("could not find commit %s"), oid_to_hex(&oid));
 576         c->graph_pos = pos;
 577         return &commit_list_insert(c, pptr)->next;
 578 }
 579
 580 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 581 {
 582         const unsigned char *commit_data;
 583         uint32_t lex_index;
 584
 585         while (pos < g->num_commits_in_base)
 586                 g = g->base_graph;
 587
 588         lex_index = pos - g->num_commits_in_base;
 589         commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * lex_index;
 590         item->graph_pos = pos;
 591         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 592 }
 593
 594 static inline void set_commit_tree(struct commit *c, struct tree *t)
 595 {
 596         c->maybe_tree = t;
 597 }
 598
 599 static int fill_commit_in_graph(struct repository *r,
 600                                 struct commit *item,
 601                                 struct commit_graph *g, uint32_t pos)
 602 {
 603         uint32_t edge_value;
 604         uint32_t *parent_data_ptr;
 605         uint64_t date_low, date_high;
 606         struct commit_list **pptr;
 607         const unsigned char *commit_data;
 608         uint32_t lex_index;
 609
 610         while (pos < g->num_commits_in_base)
 611                 g = g->base_graph;
 612
 613         if (pos >= g->num_commits + g->num_commits_in_base)
 614                 die(_("invalid commit position. commit-graph is likely corrupt"));
 615
 616         /*
 617          * Store the "full" position, but then use the
 618          * "local" position for the rest of the calculation.
 619          */
 620         item->graph_pos = pos;
 621         lex_index = pos - g->num_commits_in_base;
 622
 623         commit_data = g->chunk_commit_data + (g->hash_len + 16) * lex_index;
 624
 625         item->object.parsed = 1;
 626
 627         set_commit_tree(item, NULL);
 628
 629         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 630         date_low = get_be32(commit_data + g->hash_len + 12);
 631         item->date = (timestamp_t)((date_high << 32) | date_low);
 632
 633         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 634
 635         pptr = &item->parents;
 636
 637         edge_value = get_be32(commit_data + g->hash_len);
 638         if (edge_value == GRAPH_PARENT_NONE)
 639                 return 1;
 640         pptr = insert_parent_or_die(r, g, edge_value, pptr);
 641
 642         edge_value = get_be32(commit_data + g->hash_len + 4);
 643         if (edge_value == GRAPH_PARENT_NONE)
 644                 return 1;
 645         if (!(edge_value & GRAPH_EXTRA_EDGES_NEEDED)) {
 646                 pptr = insert_parent_or_die(r, g, edge_value, pptr);
 647                 return 1;
 648         }
 649
 650         parent_data_ptr = (uint32_t*)(g->chunk_extra_edges +
 651                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 652         do {
 653                 edge_value = get_be32(parent_data_ptr);
 654                 pptr = insert_parent_or_die(r, g,
 655                                             edge_value & GRAPH_EDGE_LAST_MASK,
 656                                             pptr);
 657                 parent_data_ptr++;
 658         } while (!(edge_value & GRAPH_LAST_EDGE));
 659
 660         return 1;
 661 }
 662
 663 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 664 {
 665         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 666                 *pos = item->graph_pos;
 667                 return 1;
 668         } else {
 669                 struct commit_graph *cur_g = g;
 670                 uint32_t lex_index;
 671
 672                 while (cur_g && !bsearch_graph(cur_g, &(item->object.oid), &lex_index))
 673                         cur_g = cur_g->base_graph;
 674
 675                 if (cur_g) {
 676                         *pos = lex_index + cur_g->num_commits_in_base;
 677                         return 1;
 678                 }
 679
 680                 return 0;
 681         }
 682 }
 683
 684 static int parse_commit_in_graph_one(struct repository *r,
 685                                      struct commit_graph *g,
 686                                      struct commit *item)
 687 {
 688         uint32_t pos;
 689
 690         if (item->object.parsed)
 691                 return 1;
 692
 693         if (find_commit_in_graph(item, g, &pos))
 694                 return fill_commit_in_graph(r, item, g, pos);
 695
 696         return 0;
 697 }
 698
 699 int parse_commit_in_graph(struct repository *r, struct commit *item)
 700 {
 701         if (!prepare_commit_graph(r))
 702                 return 0;
 703         return parse_commit_in_graph_one(r, r->objects->commit_graph, item);
 704 }
 705
 706 void load_commit_graph_info(struct repository *r, struct commit *item)
 707 {
 708         uint32_t pos;
 709         if (!prepare_commit_graph(r))
 710                 return;
 711         if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
 712                 fill_commit_graph_info(item, r->objects->commit_graph, pos);
 713 }
 714
 715 static struct tree *load_tree_for_commit(struct repository *r,
 716                                          struct commit_graph *g,
 717                                          struct commit *c)
 718 {
 719         struct object_id oid;
 720         const unsigned char *commit_data;
 721
 722         while (c->graph_pos < g->num_commits_in_base)
 723                 g = g->base_graph;
 724
 725         commit_data = g->chunk_commit_data +
 726                         GRAPH_DATA_WIDTH * (c->graph_pos - g->num_commits_in_base);
 727
 728         hashcpy(oid.hash, commit_data);
 729         set_commit_tree(c, lookup_tree(r, &oid));
 730
 731         return c->maybe_tree;
 732 }
 733
 734 static struct tree *get_commit_tree_in_graph_one(struct repository *r,
 735                                                  struct commit_graph *g,
 736                                                  const struct commit *c)
 737 {
 738         if (c->maybe_tree)
 739                 return c->maybe_tree;
 740         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 741                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 742
 743         return load_tree_for_commit(r, g, (struct commit *)c);
 744 }
 745
 746 struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
 747 {
 748         return get_commit_tree_in_graph_one(r, r->objects->commit_graph, c);
 749 }
 750
 751 struct packed_commit_list {
 752         struct commit **list;
 753         int nr;
 754         int alloc;
 755 };
 756
 757 struct packed_oid_list {
 758         struct object_id *list;
 759         int nr;
 760         int alloc;
 761 };
 762
 763 struct write_commit_graph_context {
 764         struct repository *r;
 765         struct object_directory *odb;
 766         char *graph_name;
 767         struct packed_oid_list oids;
 768         struct packed_commit_list commits;
 769         int num_extra_edges;
 770         unsigned long approx_nr_objects;
 771         struct progress *progress;
 772         int progress_done;
 773         uint64_t progress_cnt;
 774
 775         char *base_graph_name;
 776         int num_commit_graphs_before;
 777         int num_commit_graphs_after;
 778         char **commit_graph_filenames_before;
 779         char **commit_graph_filenames_after;
 780         char **commit_graph_hash_after;
 781         uint32_t new_num_commits_in_base;
 782         struct commit_graph *new_base_graph;
 783
 784         unsigned append:1,
 785                  report_progress:1,
 786                  split:1,
 787                  check_oids:1;
 788
 789         const struct split_commit_graph_opts *split_opts;
 790 };
 791
 792 static void write_graph_chunk_fanout(struct hashfile *f,
 793                                      struct write_commit_graph_context *ctx)
 794 {
 795         int i, count = 0;
 796         struct commit **list = ctx->commits.list;
 797
 798         /*
 799          * Write the first-level table (the list is sorted,
 800          * but we use a 256-entry lookup to be able to avoid
 801          * having to do eight extra binary search iterations).
 802          */
 803         for (i = 0; i < 256; i++) {
 804                 while (count < ctx->commits.nr) {
 805                         if ((*list)->object.oid.hash[0] != i)
 806                                 break;
 807                         display_progress(ctx->progress, ++ctx->progress_cnt);
 808                         count++;
 809                         list++;
 810                 }
 811
 812                 hashwrite_be32(f, count);
 813         }
 814 }
 815
 816 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 817                                    struct write_commit_graph_context *ctx)
 818 {
 819         struct commit **list = ctx->commits.list;
 820         int count;
 821         for (count = 0; count < ctx->commits.nr; count++, list++) {
 822                 display_progress(ctx->progress, ++ctx->progress_cnt);
 823                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 824         }
 825 }
 826
 827 static const unsigned char *commit_to_sha1(size_t index, void *table)
 828 {
 829         struct commit **commits = table;
 830         return commits[index]->object.oid.hash;
 831 }
 832
 833 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 834                                    struct write_commit_graph_context *ctx)
 835 {
 836         struct commit **list = ctx->commits.list;
 837         struct commit **last = ctx->commits.list + ctx->commits.nr;
 838         uint32_t num_extra_edges = 0;
 839
 840         while (list < last) {
 841                 struct commit_list *parent;
 842                 struct object_id *tree;
 843                 int edge_value;
 844                 uint32_t packedDate[2];
 845                 display_progress(ctx->progress, ++ctx->progress_cnt);
 846
 847                 if (parse_commit_no_graph(*list))
 848                         die(_("unable to parse commit %s"),
 849                                 oid_to_hex(&(*list)->object.oid));
 850                 tree = get_commit_tree_oid(*list);
 851                 hashwrite(f, tree->hash, hash_len);
 852
 853                 parent = (*list)->parents;
 854
 855                 if (!parent)
 856                         edge_value = GRAPH_PARENT_NONE;
 857                 else {
 858                         edge_value = sha1_pos(parent->item->object.oid.hash,
 859                                               ctx->commits.list,
 860                                               ctx->commits.nr,
 861                                               commit_to_sha1);
 862
 863                         if (edge_value >= 0)
 864                                 edge_value += ctx->new_num_commits_in_base;
 865                         else if (ctx->new_base_graph) {
 866                                 uint32_t pos;
 867                                 if (find_commit_in_graph(parent->item,
 868                                                          ctx->new_base_graph,
 869                                                          &pos))
 870                                         edge_value = pos;
 871                         }
 872
 873                         if (edge_value < 0)
 874                                 BUG("missing parent %s for commit %s",
 875                                     oid_to_hex(&parent->item->object.oid),
 876                                     oid_to_hex(&(*list)->object.oid));
 877                 }
 878
 879                 hashwrite_be32(f, edge_value);
 880
 881                 if (parent)
 882                         parent = parent->next;
 883
 884                 if (!parent)
 885                         edge_value = GRAPH_PARENT_NONE;
 886                 else if (parent->next)
 887                         edge_value = GRAPH_EXTRA_EDGES_NEEDED | num_extra_edges;
 888                 else {
 889                         edge_value = sha1_pos(parent->item->object.oid.hash,
 890                                               ctx->commits.list,
 891                                               ctx->commits.nr,
 892                                               commit_to_sha1);
 893
 894                         if (edge_value >= 0)
 895                                 edge_value += ctx->new_num_commits_in_base;
 896                         else if (ctx->new_base_graph) {
 897                                 uint32_t pos;
 898                                 if (find_commit_in_graph(parent->item,
 899                                                          ctx->new_base_graph,
 900                                                          &pos))
 901                                         edge_value = pos;
 902                         }
 903
 904                         if (edge_value < 0)
 905                                 BUG("missing parent %s for commit %s",
 906                                     oid_to_hex(&parent->item->object.oid),
 907                                     oid_to_hex(&(*list)->object.oid));
 908                 }
 909
 910                 hashwrite_be32(f, edge_value);
 911
 912                 if (edge_value & GRAPH_EXTRA_EDGES_NEEDED) {
 913                         do {
 914                                 num_extra_edges++;
 915                                 parent = parent->next;
 916                         } while (parent);
 917                 }
 918
 919                 if (sizeof((*list)->date) > 4)
 920                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 921                 else
 922                         packedDate[0] = 0;
 923
 924                 packedDate[0] |= htonl((*list)->generation << 2);
 925
 926                 packedDate[1] = htonl((*list)->date);
 927                 hashwrite(f, packedDate, 8);
 928
 929                 list++;
 930         }
 931 }
 932
 933 static void write_graph_chunk_extra_edges(struct hashfile *f,
 934                                           struct write_commit_graph_context *ctx)
 935 {
 936         struct commit **list = ctx->commits.list;
 937         struct commit **last = ctx->commits.list + ctx->commits.nr;
 938         struct commit_list *parent;
 939
 940         while (list < last) {
 941                 int num_parents = 0;
 942
 943                 display_progress(ctx->progress, ++ctx->progress_cnt);
 944
 945                 for (parent = (*list)->parents; num_parents < 3 && parent;
 946                      parent = parent->next)
 947                         num_parents++;
 948
 949                 if (num_parents <= 2) {
 950                         list++;
 951                         continue;
 952                 }
 953
 954                 /* Since num_parents > 2, this initializer is safe. */
 955                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 956                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 957                                                   ctx->commits.list,
 958                                                   ctx->commits.nr,
 959                                                   commit_to_sha1);
 960
 961                         if (edge_value >= 0)
 962                                 edge_value += ctx->new_num_commits_in_base;
 963                         else if (ctx->new_base_graph) {
 964                                 uint32_t pos;
 965                                 if (find_commit_in_graph(parent->item,
 966                                                          ctx->new_base_graph,
 967                                                          &pos))
 968                                         edge_value = pos;
 969                         }
 970
 971                         if (edge_value < 0)
 972                                 BUG("missing parent %s for commit %s",
 973                                     oid_to_hex(&parent->item->object.oid),
 974                                     oid_to_hex(&(*list)->object.oid));
 975                         else if (!parent->next)
 976                                 edge_value |= GRAPH_LAST_EDGE;
 977
 978                         hashwrite_be32(f, edge_value);
 979                 }
 980
 981                 list++;
 982         }
 983 }
 984
 985 static int oid_compare(const void *_a, const void *_b)
 986 {
 987         const struct object_id *a = (const struct object_id *)_a;
 988         const struct object_id *b = (const struct object_id *)_b;
 989         return oidcmp(a, b);
 990 }
 991
 992 static int add_packed_commits(const struct object_id *oid,
 993                               struct packed_git *pack,
 994                               uint32_t pos,
 995                               void *data)
 996 {
 997         struct write_commit_graph_context *ctx = (struct write_commit_graph_context*)data;
 998         enum object_type type;
 999         off_t offset = nth_packed_object_offset(pack, pos);
1000         struct object_info oi = OBJECT_INFO_INIT;
1001
1002         if (ctx->progress)
1003                 display_progress(ctx->progress, ++ctx->progress_done);
1004
1005         oi.typep = &type;
1006         if (packed_object_info(ctx->r, pack, offset, &oi) < 0)
1007                 die(_("unable to get type of object %s"), oid_to_hex(oid));
1008
1009         if (type != OBJ_COMMIT)
1010                 return 0;
1011
1012         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
1013         oidcpy(&(ctx->oids.list[ctx->oids.nr]), oid);
1014         ctx->oids.nr++;
1015
1016         return 0;
1017 }
1018
1019 static void add_missing_parents(struct write_commit_graph_context *ctx, struct commit *commit)
1020 {
1021         struct commit_list *parent;
1022         for (parent = commit->parents; parent; parent = parent->next) {
1023                 if (!(parent->item->object.flags & REACHABLE)) {
1024                         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
1025                         oidcpy(&ctx->oids.list[ctx->oids.nr], &(parent->item->object.oid));
1026                         ctx->oids.nr++;
1027                         parent->item->object.flags |= REACHABLE;
1028                 }
1029         }
1030 }
1031
1032 static void close_reachable(struct write_commit_graph_context *ctx)
1033 {
1034         int i;
1035         struct commit *commit;
1036         enum commit_graph_split_flags flags = ctx->split_opts ?
1037                 ctx->split_opts->flags : COMMIT_GRAPH_SPLIT_UNSPECIFIED;
1038
1039         if (ctx->report_progress)
1040                 ctx->progress = start_delayed_progress(
1041                                         _("Loading known commits in commit graph"),
1042                                         ctx->oids.nr);
1043         for (i = 0; i < ctx->oids.nr; i++) {
1044                 display_progress(ctx->progress, i + 1);
1045                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
1046                 if (commit)
1047                         commit->object.flags |= REACHABLE;
1048         }
1049         stop_progress(&ctx->progress);
1050
1051         /*
1052          * As this loop runs, ctx->oids.nr may grow, but not more
1053          * than the number of missing commits in the reachable
1054          * closure.
1055          */
1056         if (ctx->report_progress)
1057                 ctx->progress = start_delayed_progress(
1058                                         _("Expanding reachable commits in commit graph"),
1059                                         0);
1060         for (i = 0; i < ctx->oids.nr; i++) {
1061                 display_progress(ctx->progress, i + 1);
1062                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
1063
1064                 if (!commit)
1065                         continue;
1066                 if (ctx->split) {
1067                         if ((!parse_commit(commit) &&
1068                              commit->graph_pos == COMMIT_NOT_FROM_GRAPH) ||
1069                             flags == COMMIT_GRAPH_SPLIT_REPLACE)
1070                                 add_missing_parents(ctx, commit);
1071                 } else if (!parse_commit_no_graph(commit))
1072                         add_missing_parents(ctx, commit);
1073         }
1074         stop_progress(&ctx->progress);
1075
1076         if (ctx->report_progress)
1077                 ctx->progress = start_delayed_progress(
1078                                         _("Clearing commit marks in commit graph"),
1079                                         ctx->oids.nr);
1080         for (i = 0; i < ctx->oids.nr; i++) {
1081                 display_progress(ctx->progress, i + 1);
1082                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
1083
1084                 if (commit)
1085                         commit->object.flags &= ~REACHABLE;
1086         }
1087         stop_progress(&ctx->progress);
1088 }
1089
1090 static void compute_generation_numbers(struct write_commit_graph_context *ctx)
1091 {
1092         int i;
1093         struct commit_list *list = NULL;
1094
1095         if (ctx->report_progress)
1096                 ctx->progress = start_delayed_progress(
1097                                         _("Computing commit graph generation numbers"),
1098                                         ctx->commits.nr);
1099         for (i = 0; i < ctx->commits.nr; i++) {
1100                 display_progress(ctx->progress, i + 1);
1101                 if (ctx->commits.list[i]->generation != GENERATION_NUMBER_INFINITY &&
1102                     ctx->commits.list[i]->generation != GENERATION_NUMBER_ZERO)
1103                         continue;
1104
1105                 commit_list_insert(ctx->commits.list[i], &list);
1106                 while (list) {
1107                         struct commit *current = list->item;
1108                         struct commit_list *parent;
1109                         int all_parents_computed = 1;
1110                         uint32_t max_generation = 0;
1111
1112                         for (parent = current->parents; parent; parent = parent->next) {
1113                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
1114                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
1115                                         all_parents_computed = 0;
1116                                         commit_list_insert(parent->item, &list);
1117                                         break;
1118                                 } else if (parent->item->generation > max_generation) {
1119                                         max_generation = parent->item->generation;
1120                                 }
1121                         }
1122
1123                         if (all_parents_computed) {
1124                                 current->generation = max_generation + 1;
1125                                 pop_commit(&list);
1126
1127                                 if (current->generation > GENERATION_NUMBER_MAX)
1128                                         current->generation = GENERATION_NUMBER_MAX;
1129                         }
1130                 }
1131         }
1132         stop_progress(&ctx->progress);
1133 }
1134
1135 static int add_ref_to_set(const char *refname,
1136                           const struct object_id *oid,
1137                           int flags, void *cb_data)
1138 {
1139         struct oidset *commits = (struct oidset *)cb_data;
1140
1141         oidset_insert(commits, oid);
1142         return 0;
1143 }
1144
1145 int write_commit_graph_reachable(struct object_directory *odb,
1146                                  enum commit_graph_write_flags flags,
1147                                  const struct split_commit_graph_opts *split_opts)
1148 {
1149         struct oidset commits = OIDSET_INIT;
1150         int result;
1151
1152         for_each_ref(add_ref_to_set, &commits);
1153         result = write_commit_graph(odb, NULL, &commits,
1154                                     flags, split_opts);
1155
1156         oidset_clear(&commits);
1157         return result;
1158 }
1159
1160 static int fill_oids_from_packs(struct write_commit_graph_context *ctx,
1161                                 struct string_list *pack_indexes)
1162 {
1163         uint32_t i;
1164         struct strbuf progress_title = STRBUF_INIT;
1165         struct strbuf packname = STRBUF_INIT;
1166         int dirlen;
1167
1168         strbuf_addf(&packname, "%s/pack/", ctx->odb->path);
1169         dirlen = packname.len;
1170         if (ctx->report_progress) {
1171                 strbuf_addf(&progress_title,
1172                             Q_("Finding commits for commit graph in %d pack",
1173                                "Finding commits for commit graph in %d packs",
1174                                pack_indexes->nr),
1175                             pack_indexes->nr);
1176                 ctx->progress = start_delayed_progress(progress_title.buf, 0);
1177                 ctx->progress_done = 0;
1178         }
1179         for (i = 0; i < pack_indexes->nr; i++) {
1180                 struct packed_git *p;
1181                 strbuf_setlen(&packname, dirlen);
1182                 strbuf_addstr(&packname, pack_indexes->items[i].string);
1183                 p = add_packed_git(packname.buf, packname.len, 1);
1184                 if (!p) {
1185                         error(_("error adding pack %s"), packname.buf);
1186                         return -1;
1187                 }
1188                 if (open_pack_index(p)) {
1189                         error(_("error opening index for %s"), packname.buf);
1190                         return -1;
1191                 }
1192                 for_each_object_in_pack(p, add_packed_commits, ctx,
1193                                         FOR_EACH_OBJECT_PACK_ORDER);
1194                 close_pack(p);
1195                 free(p);
1196         }
1197
1198         stop_progress(&ctx->progress);
1199         strbuf_release(&progress_title);
1200         strbuf_release(&packname);
1201
1202         return 0;
1203 }
1204
1205 static int fill_oids_from_commits(struct write_commit_graph_context *ctx,
1206                                   struct oidset *commits)
1207 {
1208         uint32_t i = 0;
1209         struct strbuf progress_title = STRBUF_INIT;
1210         struct oidset_iter iter;
1211         struct object_id *oid;
1212
1213         if (!oidset_size(commits))
1214                 return 0;
1215
1216         if (ctx->report_progress) {
1217                 strbuf_addf(&progress_title,
1218                             Q_("Finding commits for commit graph from %d ref",
1219                                "Finding commits for commit graph from %d refs",
1220                                oidset_size(commits)),
1221                             oidset_size(commits));
1222                 ctx->progress = start_delayed_progress(
1223                                         progress_title.buf,
1224                                         oidset_size(commits));
1225         }
1226
1227         oidset_iter_init(commits, &iter);
1228         while ((oid = oidset_iter_next(&iter))) {
1229                 struct commit *result;
1230
1231                 display_progress(ctx->progress, ++i);
1232
1233                 result = lookup_commit_reference_gently(ctx->r, oid, 1);
1234                 if (result) {
1235                         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
1236                         oidcpy(&ctx->oids.list[ctx->oids.nr], &(result->object.oid));
1237                         ctx->oids.nr++;
1238                 } else if (ctx->check_oids) {
1239                         error(_("invalid commit object id: %s"),
1240                               oid_to_hex(oid));
1241                         return -1;
1242                 }
1243         }
1244
1245         stop_progress(&ctx->progress);
1246         strbuf_release(&progress_title);
1247
1248         return 0;
1249 }
1250
1251 static void fill_oids_from_all_packs(struct write_commit_graph_context *ctx)
1252 {
1253         if (ctx->report_progress)
1254                 ctx->progress = start_delayed_progress(
1255                         _("Finding commits for commit graph among packed objects"),
1256                         ctx->approx_nr_objects);
1257         for_each_packed_object(add_packed_commits, ctx,
1258                                FOR_EACH_OBJECT_PACK_ORDER);
1259         if (ctx->progress_done < ctx->approx_nr_objects)
1260                 display_progress(ctx->progress, ctx->approx_nr_objects);
1261         stop_progress(&ctx->progress);
1262 }
1263
1264 static uint32_t count_distinct_commits(struct write_commit_graph_context *ctx)
1265 {
1266         uint32_t i, count_distinct = 1;
1267
1268         if (ctx->report_progress)
1269                 ctx->progress = start_delayed_progress(
1270                         _("Counting distinct commits in commit graph"),
1271                         ctx->oids.nr);
1272         display_progress(ctx->progress, 0); /* TODO: Measure QSORT() progress */
1273         QSORT(ctx->oids.list, ctx->oids.nr, oid_compare);
1274
1275         for (i = 1; i < ctx->oids.nr; i++) {
1276                 display_progress(ctx->progress, i + 1);
1277                 if (!oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i])) {
1278                         if (ctx->split) {
1279                                 struct commit *c = lookup_commit(ctx->r, &ctx->oids.list[i]);
1280
1281                                 if (!c || c->graph_pos != COMMIT_NOT_FROM_GRAPH)
1282                                         continue;
1283                         }
1284
1285                         count_distinct++;
1286                 }
1287         }
1288         stop_progress(&ctx->progress);
1289
1290         return count_distinct;
1291 }
1292
1293 static void copy_oids_to_commits(struct write_commit_graph_context *ctx)
1294 {
1295         uint32_t i;
1296         enum commit_graph_split_flags flags = ctx->split_opts ?
1297                 ctx->split_opts->flags : COMMIT_GRAPH_SPLIT_UNSPECIFIED;
1298
1299         ctx->num_extra_edges = 0;
1300         if (ctx->report_progress)
1301                 ctx->progress = start_delayed_progress(
1302                         _("Finding extra edges in commit graph"),
1303                         ctx->oids.nr);
1304         for (i = 0; i < ctx->oids.nr; i++) {
1305                 unsigned int num_parents;
1306
1307                 display_progress(ctx->progress, i + 1);
1308                 if (i > 0 && oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i]))
1309                         continue;
1310
1311                 ALLOC_GROW(ctx->commits.list, ctx->commits.nr + 1, ctx->commits.alloc);
1312                 ctx->commits.list[ctx->commits.nr] = lookup_commit(ctx->r, &ctx->oids.list[i]);
1313
1314                 if (ctx->split && flags != COMMIT_GRAPH_SPLIT_REPLACE &&
1315                     ctx->commits.list[ctx->commits.nr]->graph_pos != COMMIT_NOT_FROM_GRAPH)
1316                         continue;
1317
1318                 if (ctx->split && flags == COMMIT_GRAPH_SPLIT_REPLACE)
1319                         parse_commit(ctx->commits.list[ctx->commits.nr]);
1320                 else
1321                         parse_commit_no_graph(ctx->commits.list[ctx->commits.nr]);
1322
1323                 num_parents = commit_list_count(ctx->commits.list[ctx->commits.nr]->parents);
1324                 if (num_parents > 2)
1325                         ctx->num_extra_edges += num_parents - 1;
1326
1327                 ctx->commits.nr++;
1328         }
1329         stop_progress(&ctx->progress);
1330 }
1331
1332 static int write_graph_chunk_base_1(struct hashfile *f,
1333                                     struct commit_graph *g)
1334 {
1335         int num = 0;
1336
1337         if (!g)
1338                 return 0;
1339
1340         num = write_graph_chunk_base_1(f, g->base_graph);
1341         hashwrite(f, g->oid.hash, the_hash_algo->rawsz);
1342         return num + 1;
1343 }
1344
1345 static int write_graph_chunk_base(struct hashfile *f,
1346                                   struct write_commit_graph_context *ctx)
1347 {
1348         int num = write_graph_chunk_base_1(f, ctx->new_base_graph);
1349
1350         if (num != ctx->num_commit_graphs_after - 1) {
1351                 error(_("failed to write correct number of base graph ids"));
1352                 return -1;
1353         }
1354
1355         return 0;
1356 }
1357
1358 static int write_commit_graph_file(struct write_commit_graph_context *ctx)
1359 {
1360         uint32_t i;
1361         int fd;
1362         struct hashfile *f;
1363         struct lock_file lk = LOCK_INIT;
1364         uint32_t chunk_ids[6];
1365         uint64_t chunk_offsets[6];
1366         const unsigned hashsz = the_hash_algo->rawsz;
1367         struct strbuf progress_title = STRBUF_INIT;
1368         int num_chunks = 3;
1369         struct object_id file_hash;
1370
1371         if (ctx->split) {
1372                 struct strbuf tmp_file = STRBUF_INIT;
1373
1374                 strbuf_addf(&tmp_file,
1375                             "%s/info/commit-graphs/tmp_graph_XXXXXX",
1376                             ctx->odb->path);
1377                 ctx->graph_name = strbuf_detach(&tmp_file, NULL);
1378         } else {
1379                 ctx->graph_name = get_commit_graph_filename(ctx->odb);
1380         }
1381
1382         if (safe_create_leading_directories(ctx->graph_name)) {
1383                 UNLEAK(ctx->graph_name);
1384                 error(_("unable to create leading directories of %s"),
1385                         ctx->graph_name);
1386                 return -1;
1387         }
1388
1389         if (ctx->split) {
1390                 char *lock_name = get_chain_filename(ctx->odb);
1391
1392                 hold_lock_file_for_update(&lk, lock_name, LOCK_DIE_ON_ERROR);
1393
1394                 fd = git_mkstemp_mode(ctx->graph_name, 0444);
1395                 if (fd < 0) {
1396                         error(_("unable to create temporary graph layer"));
1397                         return -1;
1398                 }
1399
1400                 f = hashfd(fd, ctx->graph_name);
1401         } else {
1402                 hold_lock_file_for_update(&lk, ctx->graph_name, LOCK_DIE_ON_ERROR);
1403                 fd = lk.tempfile->fd;
1404                 f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
1405         }
1406
1407         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
1408         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
1409         chunk_ids[2] = GRAPH_CHUNKID_DATA;
1410         if (ctx->num_extra_edges) {
1411                 chunk_ids[num_chunks] = GRAPH_CHUNKID_EXTRAEDGES;
1412                 num_chunks++;
1413         }
1414         if (ctx->num_commit_graphs_after > 1) {
1415                 chunk_ids[num_chunks] = GRAPH_CHUNKID_BASE;
1416                 num_chunks++;
1417         }
1418
1419         chunk_ids[num_chunks] = 0;
1420
1421         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
1422         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
1423         chunk_offsets[2] = chunk_offsets[1] + hashsz * ctx->commits.nr;
1424         chunk_offsets[3] = chunk_offsets[2] + (hashsz + 16) * ctx->commits.nr;
1425
1426         num_chunks = 3;
1427         if (ctx->num_extra_edges) {
1428                 chunk_offsets[num_chunks + 1] = chunk_offsets[num_chunks] +
1429                                                 4 * ctx->num_extra_edges;
1430                 num_chunks++;
1431         }
1432         if (ctx->num_commit_graphs_after > 1) {
1433                 chunk_offsets[num_chunks + 1] = chunk_offsets[num_chunks] +
1434                                                 hashsz * (ctx->num_commit_graphs_after - 1);
1435                 num_chunks++;
1436         }
1437
1438         hashwrite_be32(f, GRAPH_SIGNATURE);
1439
1440         hashwrite_u8(f, GRAPH_VERSION);
1441         hashwrite_u8(f, oid_version());
1442         hashwrite_u8(f, num_chunks);
1443         hashwrite_u8(f, ctx->num_commit_graphs_after - 1);
1444
1445         for (i = 0; i <= num_chunks; i++) {
1446                 uint32_t chunk_write[3];
1447
1448                 chunk_write[0] = htonl(chunk_ids[i]);
1449                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
1450                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
1451                 hashwrite(f, chunk_write, 12);
1452         }
1453
1454         if (ctx->report_progress) {
1455                 strbuf_addf(&progress_title,
1456                             Q_("Writing out commit graph in %d pass",
1457                                "Writing out commit graph in %d passes",
1458                                num_chunks),
1459                             num_chunks);
1460                 ctx->progress = start_delayed_progress(
1461                         progress_title.buf,
1462                         num_chunks * ctx->commits.nr);
1463         }
1464         write_graph_chunk_fanout(f, ctx);
1465         write_graph_chunk_oids(f, hashsz, ctx);
1466         write_graph_chunk_data(f, hashsz, ctx);
1467         if (ctx->num_extra_edges)
1468                 write_graph_chunk_extra_edges(f, ctx);
1469         if (ctx->num_commit_graphs_after > 1 &&
1470             write_graph_chunk_base(f, ctx)) {
1471                 return -1;
1472         }
1473         stop_progress(&ctx->progress);
1474         strbuf_release(&progress_title);
1475
1476         if (ctx->split && ctx->base_graph_name && ctx->num_commit_graphs_after > 1) {
1477                 char *new_base_hash = xstrdup(oid_to_hex(&ctx->new_base_graph->oid));
1478                 char *new_base_name = get_split_graph_filename(ctx->new_base_graph->odb, new_base_hash);
1479
1480                 free(ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 2]);
1481                 free(ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 2]);
1482                 ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 2] = new_base_name;
1483                 ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 2] = new_base_hash;
1484         }
1485
1486         close_commit_graph(ctx->r->objects);
1487         finalize_hashfile(f, file_hash.hash, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
1488
1489         if (ctx->split) {
1490                 FILE *chainf = fdopen_lock_file(&lk, "w");
1491                 char *final_graph_name;
1492                 int result;
1493
1494                 close(fd);
1495
1496                 if (!chainf) {
1497                         error(_("unable to open commit-graph chain file"));
1498                         return -1;
1499                 }
1500
1501                 if (ctx->base_graph_name) {
1502                         const char *dest;
1503                         int idx = ctx->num_commit_graphs_after - 1;
1504                         if (ctx->num_commit_graphs_after > 1)
1505                                 idx--;
1506
1507                         dest = ctx->commit_graph_filenames_after[idx];
1508
1509                         if (strcmp(ctx->base_graph_name, dest)) {
1510                                 result = rename(ctx->base_graph_name, dest);
1511
1512                                 if (result) {
1513                                         error(_("failed to rename base commit-graph file"));
1514                                         return -1;
1515                                 }
1516                         }
1517                 } else {
1518                         char *graph_name = get_commit_graph_filename(ctx->odb);
1519                         unlink(graph_name);
1520                 }
1521
1522                 ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1] = xstrdup(oid_to_hex(&file_hash));
1523                 final_graph_name = get_split_graph_filename(ctx->odb,
1524                                         ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1]);
1525                 ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 1] = final_graph_name;
1526
1527                 result = rename(ctx->graph_name, final_graph_name);
1528
1529                 for (i = 0; i < ctx->num_commit_graphs_after; i++)
1530                         fprintf(lk.tempfile->fp, "%s\n", ctx->commit_graph_hash_after[i]);
1531
1532                 if (result) {
1533                         error(_("failed to rename temporary commit-graph file"));
1534                         return -1;
1535                 }
1536         }
1537
1538         commit_lock_file(&lk);
1539
1540         return 0;
1541 }
1542
1543 static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
1544 {
1545         struct commit_graph *g;
1546         uint32_t num_commits;
1547         enum commit_graph_split_flags flags = COMMIT_GRAPH_SPLIT_UNSPECIFIED;
1548         uint32_t i;
1549
1550         int max_commits = 0;
1551         int size_mult = 2;
1552
1553         if (ctx->split_opts) {
1554                 max_commits = ctx->split_opts->max_commits;
1555
1556                 if (ctx->split_opts->size_multiple)
1557                         size_mult = ctx->split_opts->size_multiple;
1558
1559                 flags = ctx->split_opts->flags;
1560         }
1561
1562         g = ctx->r->objects->commit_graph;
1563         num_commits = ctx->commits.nr;
1564         if (flags == COMMIT_GRAPH_SPLIT_REPLACE)
1565                 ctx->num_commit_graphs_after = 1;
1566         else
1567                 ctx->num_commit_graphs_after = ctx->num_commit_graphs_before + 1;
1568
1569         if (flags != COMMIT_GRAPH_SPLIT_MERGE_PROHIBITED &&
1570             flags != COMMIT_GRAPH_SPLIT_REPLACE) {
1571                 while (g && (g->num_commits <= size_mult * num_commits ||
1572                             (max_commits && num_commits > max_commits))) {
1573                         if (g->odb != ctx->odb)
1574                                 break;
1575
1576                         num_commits += g->num_commits;
1577                         g = g->base_graph;
1578
1579                         ctx->num_commit_graphs_after--;
1580                 }
1581         }
1582
1583         if (flags != COMMIT_GRAPH_SPLIT_REPLACE)
1584                 ctx->new_base_graph = g;
1585         else if (ctx->num_commit_graphs_after != 1)
1586                 BUG("split_graph_merge_strategy: num_commit_graphs_after "
1587                     "should be 1 with --split=replace");
1588
1589         if (ctx->num_commit_graphs_after == 2) {
1590                 char *old_graph_name = get_commit_graph_filename(g->odb);
1591
1592                 if (!strcmp(g->filename, old_graph_name) &&
1593                     g->odb != ctx->odb) {
1594                         ctx->num_commit_graphs_after = 1;
1595                         ctx->new_base_graph = NULL;
1596                 }
1597
1598                 free(old_graph_name);
1599         }
1600
1601         CALLOC_ARRAY(ctx->commit_graph_filenames_after, ctx->num_commit_graphs_after);
1602         CALLOC_ARRAY(ctx->commit_graph_hash_after, ctx->num_commit_graphs_after);
1603
1604         for (i = 0; i < ctx->num_commit_graphs_after &&
1605                     i < ctx->num_commit_graphs_before; i++)
1606                 ctx->commit_graph_filenames_after[i] = xstrdup(ctx->commit_graph_filenames_before[i]);
1607
1608         i = ctx->num_commit_graphs_before - 1;
1609         g = ctx->r->objects->commit_graph;
1610
1611         while (g) {
1612                 if (i < ctx->num_commit_graphs_after)
1613                         ctx->commit_graph_hash_after[i] = xstrdup(oid_to_hex(&g->oid));
1614
1615                 i--;
1616                 g = g->base_graph;
1617         }
1618 }
1619
1620 static void merge_commit_graph(struct write_commit_graph_context *ctx,
1621                                struct commit_graph *g)
1622 {
1623         uint32_t i;
1624         uint32_t offset = g->num_commits_in_base;
1625
1626         ALLOC_GROW(ctx->commits.list, ctx->commits.nr + g->num_commits, ctx->commits.alloc);
1627
1628         for (i = 0; i < g->num_commits; i++) {
1629                 struct object_id oid;
1630                 struct commit *result;
1631
1632                 display_progress(ctx->progress, i + 1);
1633
1634                 load_oid_from_graph(g, i + offset, &oid);
1635
1636                 /* only add commits if they still exist in the repo */
1637                 result = lookup_commit_reference_gently(ctx->r, &oid, 1);
1638
1639                 if (result) {
1640                         ctx->commits.list[ctx->commits.nr] = result;
1641                         ctx->commits.nr++;
1642                 }
1643         }
1644 }
1645
1646 static int commit_compare(const void *_a, const void *_b)
1647 {
1648         const struct commit *a = *(const struct commit **)_a;
1649         const struct commit *b = *(const struct commit **)_b;
1650         return oidcmp(&a->object.oid, &b->object.oid);
1651 }
1652
1653 static void sort_and_scan_merged_commits(struct write_commit_graph_context *ctx)
1654 {
1655         uint32_t i;
1656
1657         if (ctx->report_progress)
1658                 ctx->progress = start_delayed_progress(
1659                                         _("Scanning merged commits"),
1660                                         ctx->commits.nr);
1661
1662         QSORT(ctx->commits.list, ctx->commits.nr, commit_compare);
1663
1664         ctx->num_extra_edges = 0;
1665         for (i = 0; i < ctx->commits.nr; i++) {
1666                 display_progress(ctx->progress, i);
1667
1668                 if (i && oideq(&ctx->commits.list[i - 1]->object.oid,
1669                           &ctx->commits.list[i]->object.oid)) {
1670                         die(_("unexpected duplicate commit id %s"),
1671                             oid_to_hex(&ctx->commits.list[i]->object.oid));
1672                 } else {
1673                         unsigned int num_parents;
1674
1675                         num_parents = commit_list_count(ctx->commits.list[i]->parents);
1676                         if (num_parents > 2)
1677                                 ctx->num_extra_edges += num_parents - 1;
1678                 }
1679         }
1680
1681         stop_progress(&ctx->progress);
1682 }
1683
1684 static void merge_commit_graphs(struct write_commit_graph_context *ctx)
1685 {
1686         struct commit_graph *g = ctx->r->objects->commit_graph;
1687         uint32_t current_graph_number = ctx->num_commit_graphs_before;
1688
1689         while (g && current_graph_number >= ctx->num_commit_graphs_after) {
1690                 current_graph_number--;
1691
1692                 if (ctx->report_progress)
1693                         ctx->progress = start_delayed_progress(_("Merging commit-graph"), 0);
1694
1695                 merge_commit_graph(ctx, g);
1696                 stop_progress(&ctx->progress);
1697
1698                 g = g->base_graph;
1699         }
1700
1701         if (g) {
1702                 ctx->new_base_graph = g;
1703                 ctx->new_num_commits_in_base = g->num_commits + g->num_commits_in_base;
1704         }
1705
1706         if (ctx->new_base_graph)
1707                 ctx->base_graph_name = xstrdup(ctx->new_base_graph->filename);
1708
1709         sort_and_scan_merged_commits(ctx);
1710 }
1711
1712 static void mark_commit_graphs(struct write_commit_graph_context *ctx)
1713 {
1714         uint32_t i;
1715         time_t now = time(NULL);
1716
1717         for (i = ctx->num_commit_graphs_after - 1; i < ctx->num_commit_graphs_before; i++) {
1718                 struct stat st;
1719                 struct utimbuf updated_time;
1720
1721                 stat(ctx->commit_graph_filenames_before[i], &st);
1722
1723                 updated_time.actime = st.st_atime;
1724                 updated_time.modtime = now;
1725                 utime(ctx->commit_graph_filenames_before[i], &updated_time);
1726         }
1727 }
1728
1729 static void expire_commit_graphs(struct write_commit_graph_context *ctx)
1730 {
1731         struct strbuf path = STRBUF_INIT;
1732         DIR *dir;
1733         struct dirent *de;
1734         size_t dirnamelen;
1735         timestamp_t expire_time = time(NULL);
1736
1737         if (ctx->split_opts && ctx->split_opts->expire_time)
1738                 expire_time = ctx->split_opts->expire_time;
1739         if (!ctx->split) {
1740                 char *chain_file_name = get_chain_filename(ctx->odb);
1741                 unlink(chain_file_name);
1742                 free(chain_file_name);
1743                 ctx->num_commit_graphs_after = 0;
1744         }
1745
1746         strbuf_addstr(&path, ctx->odb->path);
1747         strbuf_addstr(&path, "/info/commit-graphs");
1748         dir = opendir(path.buf);
1749
1750         if (!dir)
1751                 goto out;
1752
1753         strbuf_addch(&path, '/');
1754         dirnamelen = path.len;
1755         while ((de = readdir(dir)) != NULL) {
1756                 struct stat st;
1757                 uint32_t i, found = 0;
1758
1759                 strbuf_setlen(&path, dirnamelen);
1760                 strbuf_addstr(&path, de->d_name);
1761
1762                 stat(path.buf, &st);
1763
1764                 if (st.st_mtime > expire_time)
1765                         continue;
1766                 if (path.len < 6 || strcmp(path.buf + path.len - 6, ".graph"))
1767                         continue;
1768
1769                 for (i = 0; i < ctx->num_commit_graphs_after; i++) {
1770                         if (!strcmp(ctx->commit_graph_filenames_after[i],
1771                                     path.buf)) {
1772                                 found = 1;
1773                                 break;
1774                         }
1775                 }
1776
1777                 if (!found)
1778                         unlink(path.buf);
1779         }
1780
1781 out:
1782         strbuf_release(&path);
1783 }
1784
1785 int write_commit_graph(struct object_directory *odb,
1786                        struct string_list *pack_indexes,
1787                        struct oidset *commits,
1788                        enum commit_graph_write_flags flags,
1789                        const struct split_commit_graph_opts *split_opts)
1790 {
1791         struct write_commit_graph_context *ctx;
1792         uint32_t i, count_distinct = 0;
1793         int res = 0;
1794         int replace = 0;
1795
1796         if (!commit_graph_compatible(the_repository))
1797                 return 0;
1798
1799         ctx = xcalloc(1, sizeof(struct write_commit_graph_context));
1800         ctx->r = the_repository;
1801         ctx->odb = odb;
1802         ctx->append = flags & COMMIT_GRAPH_WRITE_APPEND ? 1 : 0;
1803         ctx->report_progress = flags & COMMIT_GRAPH_WRITE_PROGRESS ? 1 : 0;
1804         ctx->split = flags & COMMIT_GRAPH_WRITE_SPLIT ? 1 : 0;
1805         ctx->check_oids = flags & COMMIT_GRAPH_WRITE_CHECK_OIDS ? 1 : 0;
1806         ctx->split_opts = split_opts;
1807
1808         if (ctx->split) {
1809                 struct commit_graph *g;
1810                 prepare_commit_graph(ctx->r);
1811
1812                 g = ctx->r->objects->commit_graph;
1813
1814                 while (g) {
1815                         ctx->num_commit_graphs_before++;
1816                         g = g->base_graph;
1817                 }
1818
1819                 if (ctx->num_commit_graphs_before) {
1820                         ALLOC_ARRAY(ctx->commit_graph_filenames_before, ctx->num_commit_graphs_before);
1821                         i = ctx->num_commit_graphs_before;
1822                         g = ctx->r->objects->commit_graph;
1823
1824                         while (g) {
1825                                 ctx->commit_graph_filenames_before[--i] = xstrdup(g->filename);
1826                                 g = g->base_graph;
1827                         }
1828                 }
1829
1830                 if (ctx->split_opts)
1831                         replace = ctx->split_opts->flags & COMMIT_GRAPH_SPLIT_REPLACE;
1832         }
1833
1834         ctx->approx_nr_objects = approximate_object_count();
1835         ctx->oids.alloc = ctx->approx_nr_objects / 32;
1836
1837         if (ctx->split && split_opts && ctx->oids.alloc > split_opts->max_commits)
1838                 ctx->oids.alloc = split_opts->max_commits;
1839
1840         if (ctx->append) {
1841                 prepare_commit_graph_one(ctx->r, ctx->odb);
1842                 if (ctx->r->objects->commit_graph)
1843                         ctx->oids.alloc += ctx->r->objects->commit_graph->num_commits;
1844         }
1845
1846         if (ctx->oids.alloc < 1024)
1847                 ctx->oids.alloc = 1024;
1848         ALLOC_ARRAY(ctx->oids.list, ctx->oids.alloc);
1849
1850         if (ctx->append && ctx->r->objects->commit_graph) {
1851                 struct commit_graph *g = ctx->r->objects->commit_graph;
1852                 for (i = 0; i < g->num_commits; i++) {
1853                         const unsigned char *hash = g->chunk_oid_lookup + g->hash_len * i;
1854                         hashcpy(ctx->oids.list[ctx->oids.nr++].hash, hash);
1855                 }
1856         }
1857
1858         if (pack_indexes) {
1859                 if ((res = fill_oids_from_packs(ctx, pack_indexes)))
1860                         goto cleanup;
1861         }
1862
1863         if (commits) {
1864                 if ((res = fill_oids_from_commits(ctx, commits)))
1865                         goto cleanup;
1866         }
1867
1868         if (!pack_indexes && !commits)
1869                 fill_oids_from_all_packs(ctx);
1870
1871         close_reachable(ctx);
1872
1873         count_distinct = count_distinct_commits(ctx);
1874
1875         if (count_distinct >= GRAPH_EDGE_LAST_MASK) {
1876                 error(_("the commit graph format cannot write %d commits"), count_distinct);
1877                 res = -1;
1878                 goto cleanup;
1879         }
1880
1881         ctx->commits.alloc = count_distinct;
1882         ALLOC_ARRAY(ctx->commits.list, ctx->commits.alloc);
1883
1884         copy_oids_to_commits(ctx);
1885
1886         if (ctx->commits.nr >= GRAPH_EDGE_LAST_MASK) {
1887                 error(_("too many commits to write graph"));
1888                 res = -1;
1889                 goto cleanup;
1890         }
1891
1892         if (!ctx->commits.nr && !replace)
1893                 goto cleanup;
1894
1895         if (ctx->split) {
1896                 split_graph_merge_strategy(ctx);
1897
1898                 if (!replace)
1899                         merge_commit_graphs(ctx);
1900         } else
1901                 ctx->num_commit_graphs_after = 1;
1902
1903         compute_generation_numbers(ctx);
1904
1905         res = write_commit_graph_file(ctx);
1906
1907         if (ctx->split)
1908                 mark_commit_graphs(ctx);
1909
1910         expire_commit_graphs(ctx);
1911
1912 cleanup:
1913         free(ctx->graph_name);
1914         free(ctx->commits.list);
1915         free(ctx->oids.list);
1916
1917         if (ctx->commit_graph_filenames_after) {
1918                 for (i = 0; i < ctx->num_commit_graphs_after; i++) {
1919                         free(ctx->commit_graph_filenames_after[i]);
1920                         free(ctx->commit_graph_hash_after[i]);
1921                 }
1922
1923                 for (i = 0; i < ctx->num_commit_graphs_before; i++)
1924                         free(ctx->commit_graph_filenames_before[i]);
1925
1926                 free(ctx->commit_graph_filenames_after);
1927                 free(ctx->commit_graph_filenames_before);
1928                 free(ctx->commit_graph_hash_after);
1929         }
1930
1931         free(ctx);
1932
1933         return res;
1934 }
1935
1936 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
1937 static int verify_commit_graph_error;
1938
1939 static void graph_report(const char *fmt, ...)
1940 {
1941         va_list ap;
1942
1943         verify_commit_graph_error = 1;
1944         va_start(ap, fmt);
1945         vfprintf(stderr, fmt, ap);
1946         fprintf(stderr, "\n");
1947         va_end(ap);
1948 }
1949
1950 #define GENERATION_ZERO_EXISTS 1
1951 #define GENERATION_NUMBER_EXISTS 2
1952
1953 int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
1954 {
1955         uint32_t i, cur_fanout_pos = 0;
1956         struct object_id prev_oid, cur_oid, checksum;
1957         int generation_zero = 0;
1958         struct hashfile *f;
1959         int devnull;
1960         struct progress *progress = NULL;
1961         int local_error = 0;
1962
1963         if (!g) {
1964                 graph_report("no commit-graph file loaded");
1965                 return 1;
1966         }
1967
1968         verify_commit_graph_error = verify_commit_graph_lite(g);
1969         if (verify_commit_graph_error)
1970                 return verify_commit_graph_error;
1971
1972         devnull = open("/dev/null", O_WRONLY);
1973         f = hashfd(devnull, NULL);
1974         hashwrite(f, g->data, g->data_len - g->hash_len);
1975         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
1976         if (!hasheq(checksum.hash, g->data + g->data_len - g->hash_len)) {
1977                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
1978                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
1979         }
1980
1981         for (i = 0; i < g->num_commits; i++) {
1982                 struct commit *graph_commit;
1983
1984                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1985
1986                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
1987                         graph_report(_("commit-graph has incorrect OID order: %s then %s"),
1988                                      oid_to_hex(&prev_oid),
1989                                      oid_to_hex(&cur_oid));
1990
1991                 oidcpy(&prev_oid, &cur_oid);
1992
1993                 while (cur_oid.hash[0] > cur_fanout_pos) {
1994                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1995
1996                         if (i != fanout_value)
1997                                 graph_report(_("commit-graph has incorrect fanout value: fanout[%d] = %u != %u"),
1998                                              cur_fanout_pos, fanout_value, i);
1999                         cur_fanout_pos++;
2000                 }
2001
2002                 graph_commit = lookup_commit(r, &cur_oid);
2003                 if (!parse_commit_in_graph_one(r, g, graph_commit))
2004                         graph_report(_("failed to parse commit %s from commit-graph"),
2005                                      oid_to_hex(&cur_oid));
2006         }
2007
2008         while (cur_fanout_pos < 256) {
2009                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
2010
2011                 if (g->num_commits != fanout_value)
2012                         graph_report(_("commit-graph has incorrect fanout value: fanout[%d] = %u != %u"),
2013                                      cur_fanout_pos, fanout_value, i);
2014
2015                 cur_fanout_pos++;
2016         }
2017
2018         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
2019                 return verify_commit_graph_error;
2020
2021         if (flags & COMMIT_GRAPH_WRITE_PROGRESS)
2022                 progress = start_progress(_("Verifying commits in commit graph"),
2023                                         g->num_commits);
2024
2025         for (i = 0; i < g->num_commits; i++) {
2026                 struct commit *graph_commit, *odb_commit;
2027                 struct commit_list *graph_parents, *odb_parents;
2028                 uint32_t max_generation = 0;
2029
2030                 display_progress(progress, i + 1);
2031                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
2032
2033                 graph_commit = lookup_commit(r, &cur_oid);
2034                 odb_commit = (struct commit *)create_object(r, &cur_oid, alloc_commit_node(r));
2035                 if (parse_commit_internal(odb_commit, 0, 0)) {
2036                         graph_report(_("failed to parse commit %s from object database for commit-graph"),
2037                                      oid_to_hex(&cur_oid));
2038                         continue;
2039                 }
2040
2041                 if (!oideq(&get_commit_tree_in_graph_one(r, g, graph_commit)->object.oid,
2042                            get_commit_tree_oid(odb_commit)))
2043                         graph_report(_("root tree OID for commit %s in commit-graph is %s != %s"),
2044                                      oid_to_hex(&cur_oid),
2045                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
2046                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
2047
2048                 graph_parents = graph_commit->parents;
2049                 odb_parents = odb_commit->parents;
2050
2051                 while (graph_parents) {
2052                         if (odb_parents == NULL) {
2053                                 graph_report(_("commit-graph parent list for commit %s is too long"),
2054                                              oid_to_hex(&cur_oid));
2055                                 break;
2056                         }
2057
2058                         /* parse parent in case it is in a base graph */
2059                         parse_commit_in_graph_one(r, g, graph_parents->item);
2060
2061                         if (!oideq(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
2062                                 graph_report(_("commit-graph parent for %s is %s != %s"),
2063                                              oid_to_hex(&cur_oid),
2064                                              oid_to_hex(&graph_parents->item->object.oid),
2065                                              oid_to_hex(&odb_parents->item->object.oid));
2066
2067                         if (graph_parents->item->generation > max_generation)
2068                                 max_generation = graph_parents->item->generation;
2069
2070                         graph_parents = graph_parents->next;
2071                         odb_parents = odb_parents->next;
2072                 }
2073
2074                 if (odb_parents != NULL)
2075                         graph_report(_("commit-graph parent list for commit %s terminates early"),
2076                                      oid_to_hex(&cur_oid));
2077
2078                 if (!graph_commit->generation) {
2079                         if (generation_zero == GENERATION_NUMBER_EXISTS)
2080                                 graph_report(_("commit-graph has generation number zero for commit %s, but non-zero elsewhere"),
2081                                              oid_to_hex(&cur_oid));
2082                         generation_zero = GENERATION_ZERO_EXISTS;
2083                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
2084                         graph_report(_("commit-graph has non-zero generation number for commit %s, but zero elsewhere"),
2085                                      oid_to_hex(&cur_oid));
2086
2087                 if (generation_zero == GENERATION_ZERO_EXISTS)
2088                         continue;
2089
2090                 /*
2091                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
2092                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
2093                  * extra logic in the following condition.
2094                  */
2095                 if (max_generation == GENERATION_NUMBER_MAX)
2096                         max_generation--;
2097
2098                 if (graph_commit->generation != max_generation + 1)
2099                         graph_report(_("commit-graph generation for commit %s is %u != %u"),
2100                                      oid_to_hex(&cur_oid),
2101                                      graph_commit->generation,
2102                                      max_generation + 1);
2103
2104                 if (graph_commit->date != odb_commit->date)
2105                         graph_report(_("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime),
2106                                      oid_to_hex(&cur_oid),
2107                                      graph_commit->date,
2108                                      odb_commit->date);
2109         }
2110         stop_progress(&progress);
2111
2112         local_error = verify_commit_graph_error;
2113
2114         if (!(flags & COMMIT_GRAPH_VERIFY_SHALLOW) && g->base_graph)
2115                 local_error |= verify_commit_graph(r, g->base_graph, flags);
2116
2117         return local_error;
2118 }
2119
2120 void free_commit_graph(struct commit_graph *g)
2121 {
2122         if (!g)
2123                 return;
2124         if (g->data) {
2125                 munmap((void *)g->data, g->data_len);
2126                 g->data = NULL;
2127         }
2128         free(g->filename);
2129         free(g);
2130 }
2131
2132 void disable_commit_graph(struct repository *r)
2133 {
2134         r->commit_graph_disabled = 1;
2135 }