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 char *get_split_graph_filename(const char *obj_dir,
  49                                       const char *oid_hex)
  50 {
  51         return xstrfmt("%s/info/commit-graphs/graph-%s.graph",
  52                        obj_dir,
  53                        oid_hex);
  54 }
  55
  56 static char *get_chain_filename(const char *obj_dir)
  57 {
  58         return xstrfmt("%s/info/commit-graphs/commit-graph-chain", obj_dir);
  59 }
  60
  61 static uint8_t oid_version(void)
  62 {
  63         return 1;
  64 }
  65
  66 static struct commit_graph *alloc_commit_graph(void)
  67 {
  68         struct commit_graph *g = xcalloc(1, sizeof(*g));
  69         g->graph_fd = -1;
  70
  71         return g;
  72 }
  73
  74 extern int read_replace_refs;
  75
  76 static int commit_graph_compatible(struct repository *r)
  77 {
  78         if (!r->gitdir)
  79                 return 0;
  80
  81         if (read_replace_refs) {
  82                 prepare_replace_object(r);
  83                 if (hashmap_get_size(&r->objects->replace_map->map))
  84                         return 0;
  85         }
  86
  87         prepare_commit_graft(r);
  88         if (r->parsed_objects && r->parsed_objects->grafts_nr)
  89                 return 0;
  90         if (is_repository_shallow(r))
  91                 return 0;
  92
  93         return 1;
  94 }
  95
  96 int open_commit_graph(const char *graph_file, int *fd, struct stat *st)
  97 {
  98         *fd = git_open(graph_file);
  99         if (*fd < 0)
 100                 return 0;
 101         if (fstat(*fd, st)) {
 102                 close(*fd);
 103                 return 0;
 104         }
 105         return 1;
 106 }
 107
 108 struct commit_graph *load_commit_graph_one_fd_st(int fd, struct stat *st)
 109 {
 110         void *graph_map;
 111         size_t graph_size;
 112         struct commit_graph *ret;
 113
 114         graph_size = xsize_t(st->st_size);
 115
 116         if (graph_size < GRAPH_MIN_SIZE) {
 117                 close(fd);
 118                 error(_("commit-graph file is too small"));
 119                 return NULL;
 120         }
 121         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
 122         ret = parse_commit_graph(graph_map, fd, graph_size);
 123
 124         if (!ret) {
 125                 munmap(graph_map, graph_size);
 126                 close(fd);
 127         }
 128
 129         return ret;
 130 }
 131
 132 static int verify_commit_graph_lite(struct commit_graph *g)
 133 {
 134         /*
 135          * Basic validation shared between parse_commit_graph()
 136          * which'll be called every time the graph is used, and the
 137          * much more expensive verify_commit_graph() used by
 138          * "commit-graph verify".
 139          *
 140          * There should only be very basic checks here to ensure that
 141          * we don't e.g. segfault in fill_commit_in_graph(), but
 142          * because this is a very hot codepath nothing that e.g. loops
 143          * over g->num_commits, or runs a checksum on the commit-graph
 144          * itself.
 145          */
 146         if (!g->chunk_oid_fanout) {
 147                 error("commit-graph is missing the OID Fanout chunk");
 148                 return 1;
 149         }
 150         if (!g->chunk_oid_lookup) {
 151                 error("commit-graph is missing the OID Lookup chunk");
 152                 return 1;
 153         }
 154         if (!g->chunk_commit_data) {
 155                 error("commit-graph is missing the Commit Data chunk");
 156                 return 1;
 157         }
 158
 159         return 0;
 160 }
 161
 162 struct commit_graph *parse_commit_graph(void *graph_map, int fd,
 163                                         size_t graph_size)
 164 {
 165         const unsigned char *data, *chunk_lookup;
 166         uint32_t i;
 167         struct commit_graph *graph;
 168         uint64_t last_chunk_offset;
 169         uint32_t last_chunk_id;
 170         uint32_t graph_signature;
 171         unsigned char graph_version, hash_version;
 172
 173         if (!graph_map)
 174                 return NULL;
 175
 176         if (graph_size < GRAPH_MIN_SIZE)
 177                 return NULL;
 178
 179         data = (const unsigned char *)graph_map;
 180
 181         graph_signature = get_be32(data);
 182         if (graph_signature != GRAPH_SIGNATURE) {
 183                 error(_("commit-graph signature %X does not match signature %X"),
 184                       graph_signature, GRAPH_SIGNATURE);
 185                 return NULL;
 186         }
 187
 188         graph_version = *(unsigned char*)(data + 4);
 189         if (graph_version != GRAPH_VERSION) {
 190                 error(_("commit-graph version %X does not match version %X"),
 191                       graph_version, GRAPH_VERSION);
 192                 return NULL;
 193         }
 194
 195         hash_version = *(unsigned char*)(data + 5);
 196         if (hash_version != oid_version()) {
 197                 error(_("commit-graph hash version %X does not match version %X"),
 198                       hash_version, oid_version());
 199                 return NULL;
 200         }
 201
 202         graph = alloc_commit_graph();
 203
 204         graph->hash_len = the_hash_algo->rawsz;
 205         graph->num_chunks = *(unsigned char*)(data + 6);
 206         graph->graph_fd = fd;
 207         graph->data = graph_map;
 208         graph->data_len = graph_size;
 209
 210         last_chunk_id = 0;
 211         last_chunk_offset = 8;
 212         chunk_lookup = data + 8;
 213         for (i = 0; i < graph->num_chunks; i++) {
 214                 uint32_t chunk_id;
 215                 uint64_t chunk_offset;
 216                 int chunk_repeated = 0;
 217
 218                 if (data + graph_size - chunk_lookup <
 219                     GRAPH_CHUNKLOOKUP_WIDTH) {
 220                         error(_("commit-graph chunk lookup table entry missing; file may be incomplete"));
 221                         free(graph);
 222                         return NULL;
 223                 }
 224
 225                 chunk_id = get_be32(chunk_lookup + 0);
 226                 chunk_offset = get_be64(chunk_lookup + 4);
 227
 228                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 229
 230                 if (chunk_offset > graph_size - the_hash_algo->rawsz) {
 231                         error(_("commit-graph improper chunk offset %08x%08x"), (uint32_t)(chunk_offset >> 32),
 232                               (uint32_t)chunk_offset);
 233                         free(graph);
 234                         return NULL;
 235                 }
 236
 237                 switch (chunk_id) {
 238                 case GRAPH_CHUNKID_OIDFANOUT:
 239                         if (graph->chunk_oid_fanout)
 240                                 chunk_repeated = 1;
 241                         else
 242                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 243                         break;
 244
 245                 case GRAPH_CHUNKID_OIDLOOKUP:
 246                         if (graph->chunk_oid_lookup)
 247                                 chunk_repeated = 1;
 248                         else
 249                                 graph->chunk_oid_lookup = data + chunk_offset;
 250                         break;
 251
 252                 case GRAPH_CHUNKID_DATA:
 253                         if (graph->chunk_commit_data)
 254                                 chunk_repeated = 1;
 255                         else
 256                                 graph->chunk_commit_data = data + chunk_offset;
 257                         break;
 258
 259                 case GRAPH_CHUNKID_EXTRAEDGES:
 260                         if (graph->chunk_extra_edges)
 261                                 chunk_repeated = 1;
 262                         else
 263                                 graph->chunk_extra_edges = data + chunk_offset;
 264                         break;
 265                 }
 266
 267                 if (chunk_repeated) {
 268                         error(_("commit-graph chunk id %08x appears multiple times"), chunk_id);
 269                         free(graph);
 270                         return NULL;
 271                 }
 272
 273                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 274                 {
 275                         graph->num_commits = (chunk_offset - last_chunk_offset)
 276                                              / graph->hash_len;
 277                 }
 278
 279                 last_chunk_id = chunk_id;
 280                 last_chunk_offset = chunk_offset;
 281         }
 282
 283         if (verify_commit_graph_lite(graph))
 284                 return NULL;
 285
 286         return graph;
 287 }
 288
 289 static struct commit_graph *load_commit_graph_one(const char *graph_file)
 290 {
 291
 292         struct stat st;
 293         int fd;
 294         int open_ok = open_commit_graph(graph_file, &fd, &st);
 295
 296         if (!open_ok)
 297                 return NULL;
 298
 299         return load_commit_graph_one_fd_st(fd, &st);
 300 }
 301
 302 static struct commit_graph *load_commit_graph_v1(struct repository *r, const char *obj_dir)
 303 {
 304         char *graph_name = get_commit_graph_filename(obj_dir);
 305         struct commit_graph *g = load_commit_graph_one(graph_name);
 306         free(graph_name);
 307
 308         return g;
 309 }
 310
 311 static int add_graph_to_chain(struct commit_graph *g,
 312                               struct commit_graph *chain,
 313                               struct object_id *oids,
 314                               int n)
 315 {
 316         struct commit_graph *cur_g = chain;
 317
 318         while (n) {
 319                 n--;
 320                 cur_g = cur_g->base_graph;
 321         }
 322
 323         g->base_graph = chain;
 324
 325         if (chain)
 326                 g->num_commits_in_base = chain->num_commits + chain->num_commits_in_base;
 327
 328         return 1;
 329 }
 330
 331 static struct commit_graph *load_commit_graph_chain(struct repository *r, const char *obj_dir)
 332 {
 333         struct commit_graph *graph_chain = NULL;
 334         struct strbuf line = STRBUF_INIT;
 335         struct stat st;
 336         struct object_id *oids;
 337         int i = 0, valid = 1, count;
 338         char *chain_name = get_chain_filename(obj_dir);
 339         FILE *fp;
 340         int stat_res;
 341
 342         fp = fopen(chain_name, "r");
 343         stat_res = stat(chain_name, &st);
 344         free(chain_name);
 345
 346         if (!fp ||
 347             stat_res ||
 348             st.st_size <= the_hash_algo->hexsz)
 349                 return NULL;
 350
 351         count = st.st_size / (the_hash_algo->hexsz + 1);
 352         oids = xcalloc(count, sizeof(struct object_id));
 353
 354         for (i = 0; i < count && valid; i++) {
 355                 char *graph_name;
 356                 struct commit_graph *g;
 357
 358                 if (strbuf_getline_lf(&line, fp) == EOF)
 359                         break;
 360
 361                 if (get_oid_hex(line.buf, &oids[i])) {
 362                         warning(_("invalid commit-graph chain: line '%s' not a hash"),
 363                                 line.buf);
 364                         valid = 0;
 365                         break;
 366                 }
 367
 368                 graph_name = get_split_graph_filename(obj_dir, line.buf);
 369                 g = load_commit_graph_one(graph_name);
 370                 free(graph_name);
 371
 372                 if (g && add_graph_to_chain(g, graph_chain, oids, i))
 373                         graph_chain = g;
 374                 else
 375                         valid = 0;
 376         }
 377
 378         free(oids);
 379         fclose(fp);
 380
 381         return graph_chain;
 382 }
 383
 384 static struct commit_graph *read_commit_graph_one(struct repository *r, const char *obj_dir)
 385 {
 386         struct commit_graph *g = load_commit_graph_v1(r, obj_dir);
 387
 388         if (!g)
 389                 g = load_commit_graph_chain(r, obj_dir);
 390
 391         return g;
 392 }
 393
 394 static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
 395 {
 396
 397         if (r->objects->commit_graph)
 398                 return;
 399
 400         r->objects->commit_graph = read_commit_graph_one(r, obj_dir);
 401 }
 402
 403 /*
 404  * Return 1 if commit_graph is non-NULL, and 0 otherwise.
 405  *
 406  * On the first invocation, this function attemps to load the commit
 407  * graph if the_repository is configured to have one.
 408  */
 409 static int prepare_commit_graph(struct repository *r)
 410 {
 411         struct object_directory *odb;
 412         int config_value;
 413
 414         if (git_env_bool(GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD, 0))
 415                 die("dying as requested by the '%s' variable on commit-graph load!",
 416                     GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD);
 417
 418         if (r->objects->commit_graph_attempted)
 419                 return !!r->objects->commit_graph;
 420         r->objects->commit_graph_attempted = 1;
 421
 422         if (!git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
 423             (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
 424             !config_value))
 425                 /*
 426                  * This repository is not configured to use commit graphs, so
 427                  * do not load one. (But report commit_graph_attempted anyway
 428                  * so that commit graph loading is not attempted again for this
 429                  * repository.)
 430                  */
 431                 return 0;
 432
 433         if (!commit_graph_compatible(r))
 434                 return 0;
 435
 436         prepare_alt_odb(r);
 437         for (odb = r->objects->odb;
 438              !r->objects->commit_graph && odb;
 439              odb = odb->next)
 440                 prepare_commit_graph_one(r, odb->path);
 441         return !!r->objects->commit_graph;
 442 }
 443
 444 int generation_numbers_enabled(struct repository *r)
 445 {
 446         uint32_t first_generation;
 447         struct commit_graph *g;
 448         if (!prepare_commit_graph(r))
 449                return 0;
 450
 451         g = r->objects->commit_graph;
 452
 453         if (!g->num_commits)
 454                 return 0;
 455
 456         first_generation = get_be32(g->chunk_commit_data +
 457                                     g->hash_len + 8) >> 2;
 458
 459         return !!first_generation;
 460 }
 461
 462 static void close_commit_graph_one(struct commit_graph *g)
 463 {
 464         if (!g)
 465                 return;
 466
 467         close_commit_graph_one(g->base_graph);
 468         free_commit_graph(g);
 469 }
 470
 471 void close_commit_graph(struct raw_object_store *o)
 472 {
 473         close_commit_graph_one(o->commit_graph);
 474         o->commit_graph = NULL;
 475 }
 476
 477 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 478 {
 479         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 480                             g->chunk_oid_lookup, g->hash_len, pos);
 481 }
 482
 483 static void load_oid_from_graph(struct commit_graph *g,
 484                                 uint32_t pos,
 485                                 struct object_id *oid)
 486 {
 487         uint32_t lex_index;
 488
 489         while (g && pos < g->num_commits_in_base)
 490                 g = g->base_graph;
 491
 492         if (!g)
 493                 BUG("NULL commit-graph");
 494
 495         if (pos >= g->num_commits + g->num_commits_in_base)
 496                 die(_("invalid commit position. commit-graph is likely corrupt"));
 497
 498         lex_index = pos - g->num_commits_in_base;
 499
 500         hashcpy(oid->hash, g->chunk_oid_lookup + g->hash_len * lex_index);
 501 }
 502
 503 static struct commit_list **insert_parent_or_die(struct repository *r,
 504                                                  struct commit_graph *g,
 505                                                  uint32_t pos,
 506                                                  struct commit_list **pptr)
 507 {
 508         struct commit *c;
 509         struct object_id oid;
 510
 511         if (pos >= g->num_commits + g->num_commits_in_base)
 512                 die("invalid parent position %"PRIu32, pos);
 513
 514         load_oid_from_graph(g, pos, &oid);
 515         c = lookup_commit(r, &oid);
 516         if (!c)
 517                 die(_("could not find commit %s"), oid_to_hex(&oid));
 518         c->graph_pos = pos;
 519         return &commit_list_insert(c, pptr)->next;
 520 }
 521
 522 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 523 {
 524         const unsigned char *commit_data;
 525         uint32_t lex_index;
 526
 527         while (pos < g->num_commits_in_base)
 528                 g = g->base_graph;
 529
 530         lex_index = pos - g->num_commits_in_base;
 531         commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * lex_index;
 532         item->graph_pos = pos;
 533         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 534 }
 535
 536 static int fill_commit_in_graph(struct repository *r,
 537                                 struct commit *item,
 538                                 struct commit_graph *g, uint32_t pos)
 539 {
 540         uint32_t edge_value;
 541         uint32_t *parent_data_ptr;
 542         uint64_t date_low, date_high;
 543         struct commit_list **pptr;
 544         const unsigned char *commit_data;
 545         uint32_t lex_index;
 546
 547         while (pos < g->num_commits_in_base)
 548                 g = g->base_graph;
 549
 550         if (pos >= g->num_commits + g->num_commits_in_base)
 551                 die(_("invalid commit position. commit-graph is likely corrupt"));
 552
 553         /*
 554          * Store the "full" position, but then use the
 555          * "local" position for the rest of the calculation.
 556          */
 557         item->graph_pos = pos;
 558         lex_index = pos - g->num_commits_in_base;
 559
 560         commit_data = g->chunk_commit_data + (g->hash_len + 16) * lex_index;
 561
 562         item->object.parsed = 1;
 563
 564         item->maybe_tree = NULL;
 565
 566         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 567         date_low = get_be32(commit_data + g->hash_len + 12);
 568         item->date = (timestamp_t)((date_high << 32) | date_low);
 569
 570         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 571
 572         pptr = &item->parents;
 573
 574         edge_value = get_be32(commit_data + g->hash_len);
 575         if (edge_value == GRAPH_PARENT_NONE)
 576                 return 1;
 577         pptr = insert_parent_or_die(r, g, edge_value, pptr);
 578
 579         edge_value = get_be32(commit_data + g->hash_len + 4);
 580         if (edge_value == GRAPH_PARENT_NONE)
 581                 return 1;
 582         if (!(edge_value & GRAPH_EXTRA_EDGES_NEEDED)) {
 583                 pptr = insert_parent_or_die(r, g, edge_value, pptr);
 584                 return 1;
 585         }
 586
 587         parent_data_ptr = (uint32_t*)(g->chunk_extra_edges +
 588                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 589         do {
 590                 edge_value = get_be32(parent_data_ptr);
 591                 pptr = insert_parent_or_die(r, g,
 592                                             edge_value & GRAPH_EDGE_LAST_MASK,
 593                                             pptr);
 594                 parent_data_ptr++;
 595         } while (!(edge_value & GRAPH_LAST_EDGE));
 596
 597         return 1;
 598 }
 599
 600 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 601 {
 602         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 603                 *pos = item->graph_pos;
 604                 return 1;
 605         } else {
 606                 struct commit_graph *cur_g = g;
 607                 uint32_t lex_index;
 608
 609                 while (cur_g && !bsearch_graph(cur_g, &(item->object.oid), &lex_index))
 610                         cur_g = cur_g->base_graph;
 611
 612                 if (cur_g) {
 613                         *pos = lex_index + cur_g->num_commits_in_base;
 614                         return 1;
 615                 }
 616
 617                 return 0;
 618         }
 619 }
 620
 621 static int parse_commit_in_graph_one(struct repository *r,
 622                                      struct commit_graph *g,
 623                                      struct commit *item)
 624 {
 625         uint32_t pos;
 626
 627         if (item->object.parsed)
 628                 return 1;
 629
 630         if (find_commit_in_graph(item, g, &pos))
 631                 return fill_commit_in_graph(r, item, g, pos);
 632
 633         return 0;
 634 }
 635
 636 int parse_commit_in_graph(struct repository *r, struct commit *item)
 637 {
 638         if (!prepare_commit_graph(r))
 639                 return 0;
 640         return parse_commit_in_graph_one(r, r->objects->commit_graph, item);
 641 }
 642
 643 void load_commit_graph_info(struct repository *r, struct commit *item)
 644 {
 645         uint32_t pos;
 646         if (!prepare_commit_graph(r))
 647                 return;
 648         if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
 649                 fill_commit_graph_info(item, r->objects->commit_graph, pos);
 650 }
 651
 652 static struct tree *load_tree_for_commit(struct repository *r,
 653                                          struct commit_graph *g,
 654                                          struct commit *c)
 655 {
 656         struct object_id oid;
 657         const unsigned char *commit_data;
 658
 659         while (c->graph_pos < g->num_commits_in_base)
 660                 g = g->base_graph;
 661
 662         commit_data = g->chunk_commit_data +
 663                         GRAPH_DATA_WIDTH * (c->graph_pos - g->num_commits_in_base);
 664
 665         hashcpy(oid.hash, commit_data);
 666         c->maybe_tree = lookup_tree(r, &oid);
 667
 668         return c->maybe_tree;
 669 }
 670
 671 static struct tree *get_commit_tree_in_graph_one(struct repository *r,
 672                                                  struct commit_graph *g,
 673                                                  const struct commit *c)
 674 {
 675         if (c->maybe_tree)
 676                 return c->maybe_tree;
 677         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 678                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 679
 680         return load_tree_for_commit(r, g, (struct commit *)c);
 681 }
 682
 683 struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
 684 {
 685         return get_commit_tree_in_graph_one(r, r->objects->commit_graph, c);
 686 }
 687
 688 struct packed_commit_list {
 689         struct commit **list;
 690         int nr;
 691         int alloc;
 692 };
 693
 694 struct packed_oid_list {
 695         struct object_id *list;
 696         int nr;
 697         int alloc;
 698 };
 699
 700 struct write_commit_graph_context {
 701         struct repository *r;
 702         const char *obj_dir;
 703         char *graph_name;
 704         struct packed_oid_list oids;
 705         struct packed_commit_list commits;
 706         int num_extra_edges;
 707         unsigned long approx_nr_objects;
 708         struct progress *progress;
 709         int progress_done;
 710         uint64_t progress_cnt;
 711         unsigned append:1,
 712                  report_progress:1;
 713 };
 714
 715 static void write_graph_chunk_fanout(struct hashfile *f,
 716                                      struct write_commit_graph_context *ctx)
 717 {
 718         int i, count = 0;
 719         struct commit **list = ctx->commits.list;
 720
 721         /*
 722          * Write the first-level table (the list is sorted,
 723          * but we use a 256-entry lookup to be able to avoid
 724          * having to do eight extra binary search iterations).
 725          */
 726         for (i = 0; i < 256; i++) {
 727                 while (count < ctx->commits.nr) {
 728                         if ((*list)->object.oid.hash[0] != i)
 729                                 break;
 730                         display_progress(ctx->progress, ++ctx->progress_cnt);
 731                         count++;
 732                         list++;
 733                 }
 734
 735                 hashwrite_be32(f, count);
 736         }
 737 }
 738
 739 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 740                                    struct write_commit_graph_context *ctx)
 741 {
 742         struct commit **list = ctx->commits.list;
 743         int count;
 744         for (count = 0; count < ctx->commits.nr; count++, list++) {
 745                 display_progress(ctx->progress, ++ctx->progress_cnt);
 746                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 747         }
 748 }
 749
 750 static const unsigned char *commit_to_sha1(size_t index, void *table)
 751 {
 752         struct commit **commits = table;
 753         return commits[index]->object.oid.hash;
 754 }
 755
 756 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 757                                    struct write_commit_graph_context *ctx)
 758 {
 759         struct commit **list = ctx->commits.list;
 760         struct commit **last = ctx->commits.list + ctx->commits.nr;
 761         uint32_t num_extra_edges = 0;
 762
 763         while (list < last) {
 764                 struct commit_list *parent;
 765                 int edge_value;
 766                 uint32_t packedDate[2];
 767                 display_progress(ctx->progress, ++ctx->progress_cnt);
 768
 769                 parse_commit_no_graph(*list);
 770                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 771
 772                 parent = (*list)->parents;
 773
 774                 if (!parent)
 775                         edge_value = GRAPH_PARENT_NONE;
 776                 else {
 777                         edge_value = sha1_pos(parent->item->object.oid.hash,
 778                                               ctx->commits.list,
 779                                               ctx->commits.nr,
 780                                               commit_to_sha1);
 781
 782                         if (edge_value < 0)
 783                                 BUG("missing parent %s for commit %s",
 784                                     oid_to_hex(&parent->item->object.oid),
 785                                     oid_to_hex(&(*list)->object.oid));
 786                 }
 787
 788                 hashwrite_be32(f, edge_value);
 789
 790                 if (parent)
 791                         parent = parent->next;
 792
 793                 if (!parent)
 794                         edge_value = GRAPH_PARENT_NONE;
 795                 else if (parent->next)
 796                         edge_value = GRAPH_EXTRA_EDGES_NEEDED | num_extra_edges;
 797                 else {
 798                         edge_value = sha1_pos(parent->item->object.oid.hash,
 799                                               ctx->commits.list,
 800                                               ctx->commits.nr,
 801                                               commit_to_sha1);
 802                         if (edge_value < 0)
 803                                 BUG("missing parent %s for commit %s",
 804                                     oid_to_hex(&parent->item->object.oid),
 805                                     oid_to_hex(&(*list)->object.oid));
 806                 }
 807
 808                 hashwrite_be32(f, edge_value);
 809
 810                 if (edge_value & GRAPH_EXTRA_EDGES_NEEDED) {
 811                         do {
 812                                 num_extra_edges++;
 813                                 parent = parent->next;
 814                         } while (parent);
 815                 }
 816
 817                 if (sizeof((*list)->date) > 4)
 818                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 819                 else
 820                         packedDate[0] = 0;
 821
 822                 packedDate[0] |= htonl((*list)->generation << 2);
 823
 824                 packedDate[1] = htonl((*list)->date);
 825                 hashwrite(f, packedDate, 8);
 826
 827                 list++;
 828         }
 829 }
 830
 831 static void write_graph_chunk_extra_edges(struct hashfile *f,
 832                                           struct write_commit_graph_context *ctx)
 833 {
 834         struct commit **list = ctx->commits.list;
 835         struct commit **last = ctx->commits.list + ctx->commits.nr;
 836         struct commit_list *parent;
 837
 838         while (list < last) {
 839                 int num_parents = 0;
 840
 841                 display_progress(ctx->progress, ++ctx->progress_cnt);
 842
 843                 for (parent = (*list)->parents; num_parents < 3 && parent;
 844                      parent = parent->next)
 845                         num_parents++;
 846
 847                 if (num_parents <= 2) {
 848                         list++;
 849                         continue;
 850                 }
 851
 852                 /* Since num_parents > 2, this initializer is safe. */
 853                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 854                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 855                                                   ctx->commits.list,
 856                                                   ctx->commits.nr,
 857                                                   commit_to_sha1);
 858
 859                         if (edge_value < 0)
 860                                 BUG("missing parent %s for commit %s",
 861                                     oid_to_hex(&parent->item->object.oid),
 862                                     oid_to_hex(&(*list)->object.oid));
 863                         else if (!parent->next)
 864                                 edge_value |= GRAPH_LAST_EDGE;
 865
 866                         hashwrite_be32(f, edge_value);
 867                 }
 868
 869                 list++;
 870         }
 871 }
 872
 873 static int oid_compare(const void *_a, const void *_b)
 874 {
 875         const struct object_id *a = (const struct object_id *)_a;
 876         const struct object_id *b = (const struct object_id *)_b;
 877         return oidcmp(a, b);
 878 }
 879
 880 static int add_packed_commits(const struct object_id *oid,
 881                               struct packed_git *pack,
 882                               uint32_t pos,
 883                               void *data)
 884 {
 885         struct write_commit_graph_context *ctx = (struct write_commit_graph_context*)data;
 886         enum object_type type;
 887         off_t offset = nth_packed_object_offset(pack, pos);
 888         struct object_info oi = OBJECT_INFO_INIT;
 889
 890         if (ctx->progress)
 891                 display_progress(ctx->progress, ++ctx->progress_done);
 892
 893         oi.typep = &type;
 894         if (packed_object_info(ctx->r, pack, offset, &oi) < 0)
 895                 die(_("unable to get type of object %s"), oid_to_hex(oid));
 896
 897         if (type != OBJ_COMMIT)
 898                 return 0;
 899
 900         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
 901         oidcpy(&(ctx->oids.list[ctx->oids.nr]), oid);
 902         ctx->oids.nr++;
 903
 904         return 0;
 905 }
 906
 907 static void add_missing_parents(struct write_commit_graph_context *ctx, struct commit *commit)
 908 {
 909         struct commit_list *parent;
 910         for (parent = commit->parents; parent; parent = parent->next) {
 911                 if (!(parent->item->object.flags & UNINTERESTING)) {
 912                         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
 913                         oidcpy(&ctx->oids.list[ctx->oids.nr], &(parent->item->object.oid));
 914                         ctx->oids.nr++;
 915                         parent->item->object.flags |= UNINTERESTING;
 916                 }
 917         }
 918 }
 919
 920 static void close_reachable(struct write_commit_graph_context *ctx)
 921 {
 922         int i;
 923         struct commit *commit;
 924
 925         if (ctx->report_progress)
 926                 ctx->progress = start_delayed_progress(
 927                                         _("Loading known commits in commit graph"),
 928                                         ctx->oids.nr);
 929         for (i = 0; i < ctx->oids.nr; i++) {
 930                 display_progress(ctx->progress, i + 1);
 931                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
 932                 if (commit)
 933                         commit->object.flags |= UNINTERESTING;
 934         }
 935         stop_progress(&ctx->progress);
 936
 937         /*
 938          * As this loop runs, ctx->oids.nr may grow, but not more
 939          * than the number of missing commits in the reachable
 940          * closure.
 941          */
 942         if (ctx->report_progress)
 943                 ctx->progress = start_delayed_progress(
 944                                         _("Expanding reachable commits in commit graph"),
 945                                         ctx->oids.nr);
 946         for (i = 0; i < ctx->oids.nr; i++) {
 947                 display_progress(ctx->progress, i + 1);
 948                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
 949
 950                 if (commit && !parse_commit_no_graph(commit))
 951                         add_missing_parents(ctx, commit);
 952         }
 953         stop_progress(&ctx->progress);
 954
 955         if (ctx->report_progress)
 956                 ctx->progress = start_delayed_progress(
 957                                         _("Clearing commit marks in commit graph"),
 958                                         ctx->oids.nr);
 959         for (i = 0; i < ctx->oids.nr; i++) {
 960                 display_progress(ctx->progress, i + 1);
 961                 commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
 962
 963                 if (commit)
 964                         commit->object.flags &= ~UNINTERESTING;
 965         }
 966         stop_progress(&ctx->progress);
 967 }
 968
 969 static void compute_generation_numbers(struct write_commit_graph_context *ctx)
 970 {
 971         int i;
 972         struct commit_list *list = NULL;
 973
 974         if (ctx->report_progress)
 975                 ctx->progress = start_progress(
 976                                         _("Computing commit graph generation numbers"),
 977                                         ctx->commits.nr);
 978         for (i = 0; i < ctx->commits.nr; i++) {
 979                 display_progress(ctx->progress, i + 1);
 980                 if (ctx->commits.list[i]->generation != GENERATION_NUMBER_INFINITY &&
 981                     ctx->commits.list[i]->generation != GENERATION_NUMBER_ZERO)
 982                         continue;
 983
 984                 commit_list_insert(ctx->commits.list[i], &list);
 985                 while (list) {
 986                         struct commit *current = list->item;
 987                         struct commit_list *parent;
 988                         int all_parents_computed = 1;
 989                         uint32_t max_generation = 0;
 990
 991                         for (parent = current->parents; parent; parent = parent->next) {
 992                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 993                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 994                                         all_parents_computed = 0;
 995                                         commit_list_insert(parent->item, &list);
 996                                         break;
 997                                 } else if (parent->item->generation > max_generation) {
 998                                         max_generation = parent->item->generation;
 999                                 }
1000                         }
1001
1002                         if (all_parents_computed) {
1003                                 current->generation = max_generation + 1;
1004                                 pop_commit(&list);
1005
1006                                 if (current->generation > GENERATION_NUMBER_MAX)
1007                                         current->generation = GENERATION_NUMBER_MAX;
1008                         }
1009                 }
1010         }
1011         stop_progress(&ctx->progress);
1012 }
1013
1014 static int add_ref_to_list(const char *refname,
1015                            const struct object_id *oid,
1016                            int flags, void *cb_data)
1017 {
1018         struct string_list *list = (struct string_list *)cb_data;
1019
1020         string_list_append(list, oid_to_hex(oid));
1021         return 0;
1022 }
1023
1024 int write_commit_graph_reachable(const char *obj_dir, unsigned int flags)
1025 {
1026         struct string_list list = STRING_LIST_INIT_DUP;
1027         int result;
1028
1029         for_each_ref(add_ref_to_list, &list);
1030         result = write_commit_graph(obj_dir, NULL, &list,
1031                                     flags);
1032
1033         string_list_clear(&list, 0);
1034         return result;
1035 }
1036
1037 static int fill_oids_from_packs(struct write_commit_graph_context *ctx,
1038                                 struct string_list *pack_indexes)
1039 {
1040         uint32_t i;
1041         struct strbuf progress_title = STRBUF_INIT;
1042         struct strbuf packname = STRBUF_INIT;
1043         int dirlen;
1044
1045         strbuf_addf(&packname, "%s/pack/", ctx->obj_dir);
1046         dirlen = packname.len;
1047         if (ctx->report_progress) {
1048                 strbuf_addf(&progress_title,
1049                             Q_("Finding commits for commit graph in %d pack",
1050                                "Finding commits for commit graph in %d packs",
1051                                pack_indexes->nr),
1052                             pack_indexes->nr);
1053                 ctx->progress = start_delayed_progress(progress_title.buf, 0);
1054                 ctx->progress_done = 0;
1055         }
1056         for (i = 0; i < pack_indexes->nr; i++) {
1057                 struct packed_git *p;
1058                 strbuf_setlen(&packname, dirlen);
1059                 strbuf_addstr(&packname, pack_indexes->items[i].string);
1060                 p = add_packed_git(packname.buf, packname.len, 1);
1061                 if (!p) {
1062                         error(_("error adding pack %s"), packname.buf);
1063                         return -1;
1064                 }
1065                 if (open_pack_index(p)) {
1066                         error(_("error opening index for %s"), packname.buf);
1067                         return -1;
1068                 }
1069                 for_each_object_in_pack(p, add_packed_commits, ctx,
1070                                         FOR_EACH_OBJECT_PACK_ORDER);
1071                 close_pack(p);
1072                 free(p);
1073         }
1074
1075         stop_progress(&ctx->progress);
1076         strbuf_reset(&progress_title);
1077         strbuf_release(&packname);
1078
1079         return 0;
1080 }
1081
1082 static void fill_oids_from_commit_hex(struct write_commit_graph_context *ctx,
1083                                       struct string_list *commit_hex)
1084 {
1085         uint32_t i;
1086         struct strbuf progress_title = STRBUF_INIT;
1087
1088         if (ctx->report_progress) {
1089                 strbuf_addf(&progress_title,
1090                             Q_("Finding commits for commit graph from %d ref",
1091                                "Finding commits for commit graph from %d refs",
1092                                commit_hex->nr),
1093                             commit_hex->nr);
1094                 ctx->progress = start_delayed_progress(
1095                                         progress_title.buf,
1096                                         commit_hex->nr);
1097         }
1098         for (i = 0; i < commit_hex->nr; i++) {
1099                 const char *end;
1100                 struct object_id oid;
1101                 struct commit *result;
1102
1103                 display_progress(ctx->progress, i + 1);
1104                 if (commit_hex->items[i].string &&
1105                     parse_oid_hex(commit_hex->items[i].string, &oid, &end))
1106                         continue;
1107
1108                 result = lookup_commit_reference_gently(ctx->r, &oid, 1);
1109
1110                 if (result) {
1111                         ALLOC_GROW(ctx->oids.list, ctx->oids.nr + 1, ctx->oids.alloc);
1112                         oidcpy(&ctx->oids.list[ctx->oids.nr], &(result->object.oid));
1113                         ctx->oids.nr++;
1114                 }
1115         }
1116         stop_progress(&ctx->progress);
1117         strbuf_release(&progress_title);
1118 }
1119
1120 static void fill_oids_from_all_packs(struct write_commit_graph_context *ctx)
1121 {
1122         if (ctx->report_progress)
1123                 ctx->progress = start_delayed_progress(
1124                         _("Finding commits for commit graph among packed objects"),
1125                         ctx->approx_nr_objects);
1126         for_each_packed_object(add_packed_commits, ctx,
1127                                FOR_EACH_OBJECT_PACK_ORDER);
1128         if (ctx->progress_done < ctx->approx_nr_objects)
1129                 display_progress(ctx->progress, ctx->approx_nr_objects);
1130         stop_progress(&ctx->progress);
1131 }
1132
1133 static uint32_t count_distinct_commits(struct write_commit_graph_context *ctx)
1134 {
1135         uint32_t i, count_distinct = 1;
1136
1137         if (ctx->report_progress)
1138                 ctx->progress = start_delayed_progress(
1139                         _("Counting distinct commits in commit graph"),
1140                         ctx->oids.nr);
1141         display_progress(ctx->progress, 0); /* TODO: Measure QSORT() progress */
1142         QSORT(ctx->oids.list, ctx->oids.nr, oid_compare);
1143
1144         for (i = 1; i < ctx->oids.nr; i++) {
1145                 display_progress(ctx->progress, i + 1);
1146                 if (!oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i]))
1147                         count_distinct++;
1148         }
1149         stop_progress(&ctx->progress);
1150
1151         return count_distinct;
1152 }
1153
1154 static void copy_oids_to_commits(struct write_commit_graph_context *ctx)
1155 {
1156         uint32_t i;
1157         struct commit_list *parent;
1158
1159         ctx->num_extra_edges = 0;
1160         if (ctx->report_progress)
1161                 ctx->progress = start_delayed_progress(
1162                         _("Finding extra edges in commit graph"),
1163                         ctx->oids.nr);
1164         for (i = 0; i < ctx->oids.nr; i++) {
1165                 int num_parents = 0;
1166                 display_progress(ctx->progress, i + 1);
1167                 if (i > 0 && oideq(&ctx->oids.list[i - 1], &ctx->oids.list[i]))
1168                         continue;
1169
1170                 ctx->commits.list[ctx->commits.nr] = lookup_commit(ctx->r, &ctx->oids.list[i]);
1171                 parse_commit_no_graph(ctx->commits.list[ctx->commits.nr]);
1172
1173                 for (parent = ctx->commits.list[ctx->commits.nr]->parents;
1174                      parent; parent = parent->next)
1175                         num_parents++;
1176
1177                 if (num_parents > 2)
1178                         ctx->num_extra_edges += num_parents - 1;
1179
1180                 ctx->commits.nr++;
1181         }
1182         stop_progress(&ctx->progress);
1183 }
1184
1185 static int write_commit_graph_file(struct write_commit_graph_context *ctx)
1186 {
1187         uint32_t i;
1188         struct hashfile *f;
1189         struct lock_file lk = LOCK_INIT;
1190         uint32_t chunk_ids[5];
1191         uint64_t chunk_offsets[5];
1192         const unsigned hashsz = the_hash_algo->rawsz;
1193         struct strbuf progress_title = STRBUF_INIT;
1194         int num_chunks = ctx->num_extra_edges ? 4 : 3;
1195
1196         ctx->graph_name = get_commit_graph_filename(ctx->obj_dir);
1197         if (safe_create_leading_directories(ctx->graph_name)) {
1198                 UNLEAK(ctx->graph_name);
1199                 error(_("unable to create leading directories of %s"),
1200                         ctx->graph_name);
1201                 return -1;
1202         }
1203
1204         hold_lock_file_for_update(&lk, ctx->graph_name, LOCK_DIE_ON_ERROR);
1205         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
1206
1207         hashwrite_be32(f, GRAPH_SIGNATURE);
1208
1209         hashwrite_u8(f, GRAPH_VERSION);
1210         hashwrite_u8(f, oid_version());
1211         hashwrite_u8(f, num_chunks);
1212         hashwrite_u8(f, 0); /* unused padding byte */
1213
1214         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
1215         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
1216         chunk_ids[2] = GRAPH_CHUNKID_DATA;
1217         if (ctx->num_extra_edges)
1218                 chunk_ids[3] = GRAPH_CHUNKID_EXTRAEDGES;
1219         else
1220                 chunk_ids[3] = 0;
1221         chunk_ids[4] = 0;
1222
1223         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
1224         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
1225         chunk_offsets[2] = chunk_offsets[1] + hashsz * ctx->commits.nr;
1226         chunk_offsets[3] = chunk_offsets[2] + (hashsz + 16) * ctx->commits.nr;
1227         chunk_offsets[4] = chunk_offsets[3] + 4 * ctx->num_extra_edges;
1228
1229         for (i = 0; i <= num_chunks; i++) {
1230                 uint32_t chunk_write[3];
1231
1232                 chunk_write[0] = htonl(chunk_ids[i]);
1233                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
1234                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
1235                 hashwrite(f, chunk_write, 12);
1236         }
1237
1238         if (ctx->report_progress) {
1239                 strbuf_addf(&progress_title,
1240                             Q_("Writing out commit graph in %d pass",
1241                                "Writing out commit graph in %d passes",
1242                                num_chunks),
1243                             num_chunks);
1244                 ctx->progress = start_delayed_progress(
1245                         progress_title.buf,
1246                         num_chunks * ctx->commits.nr);
1247         }
1248         write_graph_chunk_fanout(f, ctx);
1249         write_graph_chunk_oids(f, hashsz, ctx);
1250         write_graph_chunk_data(f, hashsz, ctx);
1251         if (ctx->num_extra_edges)
1252                 write_graph_chunk_extra_edges(f, ctx);
1253         stop_progress(&ctx->progress);
1254         strbuf_release(&progress_title);
1255
1256         close_commit_graph(ctx->r->objects);
1257         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
1258         commit_lock_file(&lk);
1259
1260         return 0;
1261 }
1262
1263 int write_commit_graph(const char *obj_dir,
1264                        struct string_list *pack_indexes,
1265                        struct string_list *commit_hex,
1266                        unsigned int flags)
1267 {
1268         struct write_commit_graph_context *ctx;
1269         uint32_t i, count_distinct = 0;
1270         int res = 0;
1271
1272         if (!commit_graph_compatible(the_repository))
1273                 return 0;
1274
1275         ctx = xcalloc(1, sizeof(struct write_commit_graph_context));
1276         ctx->r = the_repository;
1277         ctx->obj_dir = obj_dir;
1278         ctx->append = flags & COMMIT_GRAPH_APPEND ? 1 : 0;
1279         ctx->report_progress = flags & COMMIT_GRAPH_PROGRESS ? 1 : 0;
1280
1281         ctx->approx_nr_objects = approximate_object_count();
1282         ctx->oids.alloc = ctx->approx_nr_objects / 32;
1283
1284         if (ctx->append) {
1285                 prepare_commit_graph_one(ctx->r, ctx->obj_dir);
1286                 if (ctx->r->objects->commit_graph)
1287                         ctx->oids.alloc += ctx->r->objects->commit_graph->num_commits;
1288         }
1289
1290         if (ctx->oids.alloc < 1024)
1291                 ctx->oids.alloc = 1024;
1292         ALLOC_ARRAY(ctx->oids.list, ctx->oids.alloc);
1293
1294         if (ctx->append && ctx->r->objects->commit_graph) {
1295                 struct commit_graph *g = ctx->r->objects->commit_graph;
1296                 for (i = 0; i < g->num_commits; i++) {
1297                         const unsigned char *hash = g->chunk_oid_lookup + g->hash_len * i;
1298                         hashcpy(ctx->oids.list[ctx->oids.nr++].hash, hash);
1299                 }
1300         }
1301
1302         if (pack_indexes) {
1303                 if ((res = fill_oids_from_packs(ctx, pack_indexes)))
1304                         goto cleanup;
1305         }
1306
1307         if (commit_hex)
1308                 fill_oids_from_commit_hex(ctx, commit_hex);
1309
1310         if (!pack_indexes && !commit_hex)
1311                 fill_oids_from_all_packs(ctx);
1312
1313         close_reachable(ctx);
1314
1315         count_distinct = count_distinct_commits(ctx);
1316
1317         if (count_distinct >= GRAPH_EDGE_LAST_MASK) {
1318                 error(_("the commit graph format cannot write %d commits"), count_distinct);
1319                 res = -1;
1320                 goto cleanup;
1321         }
1322
1323         ctx->commits.alloc = count_distinct;
1324         ALLOC_ARRAY(ctx->commits.list, ctx->commits.alloc);
1325
1326         copy_oids_to_commits(ctx);
1327
1328         if (ctx->commits.nr >= GRAPH_EDGE_LAST_MASK) {
1329                 error(_("too many commits to write graph"));
1330                 res = -1;
1331                 goto cleanup;
1332         }
1333
1334         compute_generation_numbers(ctx);
1335
1336         res = write_commit_graph_file(ctx);
1337
1338 cleanup:
1339         free(ctx->graph_name);
1340         free(ctx->commits.list);
1341         free(ctx->oids.list);
1342         free(ctx);
1343
1344         return res;
1345 }
1346
1347 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
1348 static int verify_commit_graph_error;
1349
1350 static void graph_report(const char *fmt, ...)
1351 {
1352         va_list ap;
1353
1354         verify_commit_graph_error = 1;
1355         va_start(ap, fmt);
1356         vfprintf(stderr, fmt, ap);
1357         fprintf(stderr, "\n");
1358         va_end(ap);
1359 }
1360
1361 #define GENERATION_ZERO_EXISTS 1
1362 #define GENERATION_NUMBER_EXISTS 2
1363
1364 int verify_commit_graph(struct repository *r, struct commit_graph *g)
1365 {
1366         uint32_t i, cur_fanout_pos = 0;
1367         struct object_id prev_oid, cur_oid, checksum;
1368         int generation_zero = 0;
1369         struct hashfile *f;
1370         int devnull;
1371         struct progress *progress = NULL;
1372
1373         if (!g) {
1374                 graph_report("no commit-graph file loaded");
1375                 return 1;
1376         }
1377
1378         verify_commit_graph_error = verify_commit_graph_lite(g);
1379         if (verify_commit_graph_error)
1380                 return verify_commit_graph_error;
1381
1382         devnull = open("/dev/null", O_WRONLY);
1383         f = hashfd(devnull, NULL);
1384         hashwrite(f, g->data, g->data_len - g->hash_len);
1385         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
1386         if (!hasheq(checksum.hash, g->data + g->data_len - g->hash_len)) {
1387                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
1388                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
1389         }
1390
1391         for (i = 0; i < g->num_commits; i++) {
1392                 struct commit *graph_commit;
1393
1394                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1395
1396                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
1397                         graph_report(_("commit-graph has incorrect OID order: %s then %s"),
1398                                      oid_to_hex(&prev_oid),
1399                                      oid_to_hex(&cur_oid));
1400
1401                 oidcpy(&prev_oid, &cur_oid);
1402
1403                 while (cur_oid.hash[0] > cur_fanout_pos) {
1404                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1405
1406                         if (i != fanout_value)
1407                                 graph_report(_("commit-graph has incorrect fanout value: fanout[%d] = %u != %u"),
1408                                              cur_fanout_pos, fanout_value, i);
1409                         cur_fanout_pos++;
1410                 }
1411
1412                 graph_commit = lookup_commit(r, &cur_oid);
1413                 if (!parse_commit_in_graph_one(r, g, graph_commit))
1414                         graph_report(_("failed to parse commit %s from commit-graph"),
1415                                      oid_to_hex(&cur_oid));
1416         }
1417
1418         while (cur_fanout_pos < 256) {
1419                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1420
1421                 if (g->num_commits != fanout_value)
1422                         graph_report(_("commit-graph has incorrect fanout value: fanout[%d] = %u != %u"),
1423                                      cur_fanout_pos, fanout_value, i);
1424
1425                 cur_fanout_pos++;
1426         }
1427
1428         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
1429                 return verify_commit_graph_error;
1430
1431         progress = start_progress(_("Verifying commits in commit graph"),
1432                                   g->num_commits);
1433         for (i = 0; i < g->num_commits; i++) {
1434                 struct commit *graph_commit, *odb_commit;
1435                 struct commit_list *graph_parents, *odb_parents;
1436                 uint32_t max_generation = 0;
1437
1438                 display_progress(progress, i + 1);
1439                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1440
1441                 graph_commit = lookup_commit(r, &cur_oid);
1442                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
1443                 if (parse_commit_internal(odb_commit, 0, 0)) {
1444                         graph_report(_("failed to parse commit %s from object database for commit-graph"),
1445                                      oid_to_hex(&cur_oid));
1446                         continue;
1447                 }
1448
1449                 if (!oideq(&get_commit_tree_in_graph_one(r, g, graph_commit)->object.oid,
1450                            get_commit_tree_oid(odb_commit)))
1451                         graph_report(_("root tree OID for commit %s in commit-graph is %s != %s"),
1452                                      oid_to_hex(&cur_oid),
1453                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
1454                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
1455
1456                 graph_parents = graph_commit->parents;
1457                 odb_parents = odb_commit->parents;
1458
1459                 while (graph_parents) {
1460                         if (odb_parents == NULL) {
1461                                 graph_report(_("commit-graph parent list for commit %s is too long"),
1462                                              oid_to_hex(&cur_oid));
1463                                 break;
1464                         }
1465
1466                         if (!oideq(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
1467                                 graph_report(_("commit-graph parent for %s is %s != %s"),
1468                                              oid_to_hex(&cur_oid),
1469                                              oid_to_hex(&graph_parents->item->object.oid),
1470                                              oid_to_hex(&odb_parents->item->object.oid));
1471
1472                         if (graph_parents->item->generation > max_generation)
1473                                 max_generation = graph_parents->item->generation;
1474
1475                         graph_parents = graph_parents->next;
1476                         odb_parents = odb_parents->next;
1477                 }
1478
1479                 if (odb_parents != NULL)
1480                         graph_report(_("commit-graph parent list for commit %s terminates early"),
1481                                      oid_to_hex(&cur_oid));
1482
1483                 if (!graph_commit->generation) {
1484                         if (generation_zero == GENERATION_NUMBER_EXISTS)
1485                                 graph_report(_("commit-graph has generation number zero for commit %s, but non-zero elsewhere"),
1486                                              oid_to_hex(&cur_oid));
1487                         generation_zero = GENERATION_ZERO_EXISTS;
1488                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1489                         graph_report(_("commit-graph has non-zero generation number for commit %s, but zero elsewhere"),
1490                                      oid_to_hex(&cur_oid));
1491
1492                 if (generation_zero == GENERATION_ZERO_EXISTS)
1493                         continue;
1494
1495                 /*
1496                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1497                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1498                  * extra logic in the following condition.
1499                  */
1500                 if (max_generation == GENERATION_NUMBER_MAX)
1501                         max_generation--;
1502
1503                 if (graph_commit->generation != max_generation + 1)
1504                         graph_report(_("commit-graph generation for commit %s is %u != %u"),
1505                                      oid_to_hex(&cur_oid),
1506                                      graph_commit->generation,
1507                                      max_generation + 1);
1508
1509                 if (graph_commit->date != odb_commit->date)
1510                         graph_report(_("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime),
1511                                      oid_to_hex(&cur_oid),
1512                                      graph_commit->date,
1513                                      odb_commit->date);
1514         }
1515         stop_progress(&progress);
1516
1517         return verify_commit_graph_error;
1518 }
1519
1520 void free_commit_graph(struct commit_graph *g)
1521 {
1522         if (!g)
1523                 return;
1524         if (g->graph_fd >= 0) {
1525                 munmap((void *)g->data, g->data_len);
1526                 g->data = NULL;
1527                 close(g->graph_fd);
1528         }
1529         free(g);
1530 }