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
  17 #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
  18 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  19 #define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  20 #define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
  21 #define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
  22
  23 #define GRAPH_DATA_WIDTH 36
  24
  25 #define GRAPH_VERSION_1 0x1
  26 #define GRAPH_VERSION GRAPH_VERSION_1
  27
  28 #define GRAPH_OID_VERSION_SHA1 1
  29 #define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
  30 #define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
  31 #define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
  32
  33 #define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
  34 #define GRAPH_PARENT_MISSING 0x7fffffff
  35 #define GRAPH_EDGE_LAST_MASK 0x7fffffff
  36 #define GRAPH_PARENT_NONE 0x70000000
  37
  38 #define GRAPH_LAST_EDGE 0x80000000
  39
  40 #define GRAPH_HEADER_SIZE 8
  41 #define GRAPH_FANOUT_SIZE (4 * 256)
  42 #define GRAPH_CHUNKLOOKUP_WIDTH 12
  43 #define GRAPH_MIN_SIZE (GRAPH_HEADER_SIZE + 4 * GRAPH_CHUNKLOOKUP_WIDTH \
  44                         + GRAPH_FANOUT_SIZE + GRAPH_OID_LEN)
  45
  46 char *get_commit_graph_filename(const char *obj_dir)
  47 {
  48         return xstrfmt("%s/info/commit-graph", obj_dir);
  49 }
  50
  51 static struct commit_graph *alloc_commit_graph(void)
  52 {
  53         struct commit_graph *g = xcalloc(1, sizeof(*g));
  54         g->graph_fd = -1;
  55
  56         return g;
  57 }
  58
  59 struct commit_graph *load_commit_graph_one(const char *graph_file)
  60 {
  61         void *graph_map;
  62         const unsigned char *data, *chunk_lookup;
  63         size_t graph_size;
  64         struct stat st;
  65         uint32_t i;
  66         struct commit_graph *graph;
  67         int fd = git_open(graph_file);
  68         uint64_t last_chunk_offset;
  69         uint32_t last_chunk_id;
  70         uint32_t graph_signature;
  71         unsigned char graph_version, hash_version;
  72
  73         if (fd < 0)
  74                 return NULL;
  75         if (fstat(fd, &st)) {
  76                 close(fd);
  77                 return NULL;
  78         }
  79         graph_size = xsize_t(st.st_size);
  80
  81         if (graph_size < GRAPH_MIN_SIZE) {
  82                 close(fd);
  83                 die("graph file %s is too small", graph_file);
  84         }
  85         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
  86         data = (const unsigned char *)graph_map;
  87
  88         graph_signature = get_be32(data);
  89         if (graph_signature != GRAPH_SIGNATURE) {
  90                 error("graph signature %X does not match signature %X",
  91                       graph_signature, GRAPH_SIGNATURE);
  92                 goto cleanup_fail;
  93         }
  94
  95         graph_version = *(unsigned char*)(data + 4);
  96         if (graph_version != GRAPH_VERSION) {
  97                 error("graph version %X does not match version %X",
  98                       graph_version, GRAPH_VERSION);
  99                 goto cleanup_fail;
 100         }
 101
 102         hash_version = *(unsigned char*)(data + 5);
 103         if (hash_version != GRAPH_OID_VERSION) {
 104                 error("hash version %X does not match version %X",
 105                       hash_version, GRAPH_OID_VERSION);
 106                 goto cleanup_fail;
 107         }
 108
 109         graph = alloc_commit_graph();
 110
 111         graph->hash_len = GRAPH_OID_LEN;
 112         graph->num_chunks = *(unsigned char*)(data + 6);
 113         graph->graph_fd = fd;
 114         graph->data = graph_map;
 115         graph->data_len = graph_size;
 116
 117         last_chunk_id = 0;
 118         last_chunk_offset = 8;
 119         chunk_lookup = data + 8;
 120         for (i = 0; i < graph->num_chunks; i++) {
 121                 uint32_t chunk_id = get_be32(chunk_lookup + 0);
 122                 uint64_t chunk_offset = get_be64(chunk_lookup + 4);
 123                 int chunk_repeated = 0;
 124
 125                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 126
 127                 if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
 128                         error("improper chunk offset %08x%08x", (uint32_t)(chunk_offset >> 32),
 129                               (uint32_t)chunk_offset);
 130                         goto cleanup_fail;
 131                 }
 132
 133                 switch (chunk_id) {
 134                 case GRAPH_CHUNKID_OIDFANOUT:
 135                         if (graph->chunk_oid_fanout)
 136                                 chunk_repeated = 1;
 137                         else
 138                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 139                         break;
 140
 141                 case GRAPH_CHUNKID_OIDLOOKUP:
 142                         if (graph->chunk_oid_lookup)
 143                                 chunk_repeated = 1;
 144                         else
 145                                 graph->chunk_oid_lookup = data + chunk_offset;
 146                         break;
 147
 148                 case GRAPH_CHUNKID_DATA:
 149                         if (graph->chunk_commit_data)
 150                                 chunk_repeated = 1;
 151                         else
 152                                 graph->chunk_commit_data = data + chunk_offset;
 153                         break;
 154
 155                 case GRAPH_CHUNKID_LARGEEDGES:
 156                         if (graph->chunk_large_edges)
 157                                 chunk_repeated = 1;
 158                         else
 159                                 graph->chunk_large_edges = data + chunk_offset;
 160                         break;
 161                 }
 162
 163                 if (chunk_repeated) {
 164                         error("chunk id %08x appears multiple times", chunk_id);
 165                         goto cleanup_fail;
 166                 }
 167
 168                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 169                 {
 170                         graph->num_commits = (chunk_offset - last_chunk_offset)
 171                                              / graph->hash_len;
 172                 }
 173
 174                 last_chunk_id = chunk_id;
 175                 last_chunk_offset = chunk_offset;
 176         }
 177
 178         return graph;
 179
 180 cleanup_fail:
 181         munmap(graph_map, graph_size);
 182         close(fd);
 183         exit(1);
 184 }
 185
 186 /* global storage */
 187 static struct commit_graph *commit_graph = NULL;
 188
 189 static void prepare_commit_graph_one(const char *obj_dir)
 190 {
 191         char *graph_name;
 192
 193         if (commit_graph)
 194                 return;
 195
 196         graph_name = get_commit_graph_filename(obj_dir);
 197         commit_graph = load_commit_graph_one(graph_name);
 198
 199         FREE_AND_NULL(graph_name);
 200 }
 201
 202 static int prepare_commit_graph_run_once = 0;
 203 static void prepare_commit_graph(void)
 204 {
 205         struct alternate_object_database *alt;
 206         char *obj_dir;
 207
 208         if (prepare_commit_graph_run_once)
 209                 return;
 210         prepare_commit_graph_run_once = 1;
 211
 212         obj_dir = get_object_directory();
 213         prepare_commit_graph_one(obj_dir);
 214         prepare_alt_odb(the_repository);
 215         for (alt = the_repository->objects->alt_odb_list;
 216              !commit_graph && alt;
 217              alt = alt->next)
 218                 prepare_commit_graph_one(alt->path);
 219 }
 220
 221 static void close_commit_graph(void)
 222 {
 223         if (!commit_graph)
 224                 return;
 225
 226         if (commit_graph->graph_fd >= 0) {
 227                 munmap((void *)commit_graph->data, commit_graph->data_len);
 228                 commit_graph->data = NULL;
 229                 close(commit_graph->graph_fd);
 230         }
 231
 232         FREE_AND_NULL(commit_graph);
 233 }
 234
 235 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 236 {
 237         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 238                             g->chunk_oid_lookup, g->hash_len, pos);
 239 }
 240
 241 static struct commit_list **insert_parent_or_die(struct commit_graph *g,
 242                                                  uint64_t pos,
 243                                                  struct commit_list **pptr)
 244 {
 245         struct commit *c;
 246         struct object_id oid;
 247
 248         if (pos >= g->num_commits)
 249                 die("invalid parent position %"PRIu64, pos);
 250
 251         hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
 252         c = lookup_commit(the_repository, &oid);
 253         if (!c)
 254                 die("could not find commit %s", oid_to_hex(&oid));
 255         c->graph_pos = pos;
 256         return &commit_list_insert(c, pptr)->next;
 257 }
 258
 259 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 260 {
 261         const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
 262         item->graph_pos = pos;
 263         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 264 }
 265
 266 static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
 267 {
 268         uint32_t edge_value;
 269         uint32_t *parent_data_ptr;
 270         uint64_t date_low, date_high;
 271         struct commit_list **pptr;
 272         const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
 273
 274         item->object.parsed = 1;
 275         item->graph_pos = pos;
 276
 277         item->maybe_tree = NULL;
 278
 279         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 280         date_low = get_be32(commit_data + g->hash_len + 12);
 281         item->date = (timestamp_t)((date_high << 32) | date_low);
 282
 283         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 284
 285         pptr = &item->parents;
 286
 287         edge_value = get_be32(commit_data + g->hash_len);
 288         if (edge_value == GRAPH_PARENT_NONE)
 289                 return 1;
 290         pptr = insert_parent_or_die(g, edge_value, pptr);
 291
 292         edge_value = get_be32(commit_data + g->hash_len + 4);
 293         if (edge_value == GRAPH_PARENT_NONE)
 294                 return 1;
 295         if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
 296                 pptr = insert_parent_or_die(g, edge_value, pptr);
 297                 return 1;
 298         }
 299
 300         parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
 301                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 302         do {
 303                 edge_value = get_be32(parent_data_ptr);
 304                 pptr = insert_parent_or_die(g,
 305                                             edge_value & GRAPH_EDGE_LAST_MASK,
 306                                             pptr);
 307                 parent_data_ptr++;
 308         } while (!(edge_value & GRAPH_LAST_EDGE));
 309
 310         return 1;
 311 }
 312
 313 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 314 {
 315         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 316                 *pos = item->graph_pos;
 317                 return 1;
 318         } else {
 319                 return bsearch_graph(g, &(item->object.oid), pos);
 320         }
 321 }
 322
 323 static int parse_commit_in_graph_one(struct commit_graph *g, struct commit *item)
 324 {
 325         uint32_t pos;
 326
 327         if (!core_commit_graph)
 328                 return 0;
 329         if (item->object.parsed)
 330                 return 1;
 331
 332         if (find_commit_in_graph(item, g, &pos))
 333                 return fill_commit_in_graph(item, g, pos);
 334
 335         return 0;
 336 }
 337
 338 int parse_commit_in_graph(struct commit *item)
 339 {
 340         if (!core_commit_graph)
 341                 return 0;
 342
 343         prepare_commit_graph();
 344         if (commit_graph)
 345                 return parse_commit_in_graph_one(commit_graph, item);
 346         return 0;
 347 }
 348
 349 void load_commit_graph_info(struct commit *item)
 350 {
 351         uint32_t pos;
 352         if (!core_commit_graph)
 353                 return;
 354         prepare_commit_graph();
 355         if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
 356                 fill_commit_graph_info(item, commit_graph, pos);
 357 }
 358
 359 static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
 360 {
 361         struct object_id oid;
 362         const unsigned char *commit_data = g->chunk_commit_data +
 363                                            GRAPH_DATA_WIDTH * (c->graph_pos);
 364
 365         hashcpy(oid.hash, commit_data);
 366         c->maybe_tree = lookup_tree(the_repository, &oid);
 367
 368         return c->maybe_tree;
 369 }
 370
 371 static struct tree *get_commit_tree_in_graph_one(struct commit_graph *g,
 372                                                  const struct commit *c)
 373 {
 374         if (c->maybe_tree)
 375                 return c->maybe_tree;
 376         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 377                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 378
 379         return load_tree_for_commit(g, (struct commit *)c);
 380 }
 381
 382 struct tree *get_commit_tree_in_graph(const struct commit *c)
 383 {
 384         return get_commit_tree_in_graph_one(commit_graph, c);
 385 }
 386
 387 static void write_graph_chunk_fanout(struct hashfile *f,
 388                                      struct commit **commits,
 389                                      int nr_commits)
 390 {
 391         int i, count = 0;
 392         struct commit **list = commits;
 393
 394         /*
 395          * Write the first-level table (the list is sorted,
 396          * but we use a 256-entry lookup to be able to avoid
 397          * having to do eight extra binary search iterations).
 398          */
 399         for (i = 0; i < 256; i++) {
 400                 while (count < nr_commits) {
 401                         if ((*list)->object.oid.hash[0] != i)
 402                                 break;
 403                         count++;
 404                         list++;
 405                 }
 406
 407                 hashwrite_be32(f, count);
 408         }
 409 }
 410
 411 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 412                                    struct commit **commits, int nr_commits)
 413 {
 414         struct commit **list = commits;
 415         int count;
 416         for (count = 0; count < nr_commits; count++, list++)
 417                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 418 }
 419
 420 static const unsigned char *commit_to_sha1(size_t index, void *table)
 421 {
 422         struct commit **commits = table;
 423         return commits[index]->object.oid.hash;
 424 }
 425
 426 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 427                                    struct commit **commits, int nr_commits)
 428 {
 429         struct commit **list = commits;
 430         struct commit **last = commits + nr_commits;
 431         uint32_t num_extra_edges = 0;
 432
 433         while (list < last) {
 434                 struct commit_list *parent;
 435                 int edge_value;
 436                 uint32_t packedDate[2];
 437
 438                 parse_commit(*list);
 439                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 440
 441                 parent = (*list)->parents;
 442
 443                 if (!parent)
 444                         edge_value = GRAPH_PARENT_NONE;
 445                 else {
 446                         edge_value = sha1_pos(parent->item->object.oid.hash,
 447                                               commits,
 448                                               nr_commits,
 449                                               commit_to_sha1);
 450
 451                         if (edge_value < 0)
 452                                 edge_value = GRAPH_PARENT_MISSING;
 453                 }
 454
 455                 hashwrite_be32(f, edge_value);
 456
 457                 if (parent)
 458                         parent = parent->next;
 459
 460                 if (!parent)
 461                         edge_value = GRAPH_PARENT_NONE;
 462                 else if (parent->next)
 463                         edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
 464                 else {
 465                         edge_value = sha1_pos(parent->item->object.oid.hash,
 466                                               commits,
 467                                               nr_commits,
 468                                               commit_to_sha1);
 469                         if (edge_value < 0)
 470                                 edge_value = GRAPH_PARENT_MISSING;
 471                 }
 472
 473                 hashwrite_be32(f, edge_value);
 474
 475                 if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
 476                         do {
 477                                 num_extra_edges++;
 478                                 parent = parent->next;
 479                         } while (parent);
 480                 }
 481
 482                 if (sizeof((*list)->date) > 4)
 483                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 484                 else
 485                         packedDate[0] = 0;
 486
 487                 packedDate[0] |= htonl((*list)->generation << 2);
 488
 489                 packedDate[1] = htonl((*list)->date);
 490                 hashwrite(f, packedDate, 8);
 491
 492                 list++;
 493         }
 494 }
 495
 496 static void write_graph_chunk_large_edges(struct hashfile *f,
 497                                           struct commit **commits,
 498                                           int nr_commits)
 499 {
 500         struct commit **list = commits;
 501         struct commit **last = commits + nr_commits;
 502         struct commit_list *parent;
 503
 504         while (list < last) {
 505                 int num_parents = 0;
 506                 for (parent = (*list)->parents; num_parents < 3 && parent;
 507                      parent = parent->next)
 508                         num_parents++;
 509
 510                 if (num_parents <= 2) {
 511                         list++;
 512                         continue;
 513                 }
 514
 515                 /* Since num_parents > 2, this initializer is safe. */
 516                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 517                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 518                                                   commits,
 519                                                   nr_commits,
 520                                                   commit_to_sha1);
 521
 522                         if (edge_value < 0)
 523                                 edge_value = GRAPH_PARENT_MISSING;
 524                         else if (!parent->next)
 525                                 edge_value |= GRAPH_LAST_EDGE;
 526
 527                         hashwrite_be32(f, edge_value);
 528                 }
 529
 530                 list++;
 531         }
 532 }
 533
 534 static int commit_compare(const void *_a, const void *_b)
 535 {
 536         const struct object_id *a = (const struct object_id *)_a;
 537         const struct object_id *b = (const struct object_id *)_b;
 538         return oidcmp(a, b);
 539 }
 540
 541 struct packed_commit_list {
 542         struct commit **list;
 543         int nr;
 544         int alloc;
 545 };
 546
 547 struct packed_oid_list {
 548         struct object_id *list;
 549         int nr;
 550         int alloc;
 551 };
 552
 553 static int add_packed_commits(const struct object_id *oid,
 554                               struct packed_git *pack,
 555                               uint32_t pos,
 556                               void *data)
 557 {
 558         struct packed_oid_list *list = (struct packed_oid_list*)data;
 559         enum object_type type;
 560         off_t offset = nth_packed_object_offset(pack, pos);
 561         struct object_info oi = OBJECT_INFO_INIT;
 562
 563         oi.typep = &type;
 564         if (packed_object_info(the_repository, pack, offset, &oi) < 0)
 565                 die("unable to get type of object %s", oid_to_hex(oid));
 566
 567         if (type != OBJ_COMMIT)
 568                 return 0;
 569
 570         ALLOC_GROW(list->list, list->nr + 1, list->alloc);
 571         oidcpy(&(list->list[list->nr]), oid);
 572         list->nr++;
 573
 574         return 0;
 575 }
 576
 577 static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
 578 {
 579         struct commit_list *parent;
 580         for (parent = commit->parents; parent; parent = parent->next) {
 581                 if (!(parent->item->object.flags & UNINTERESTING)) {
 582                         ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
 583                         oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
 584                         oids->nr++;
 585                         parent->item->object.flags |= UNINTERESTING;
 586                 }
 587         }
 588 }
 589
 590 static void close_reachable(struct packed_oid_list *oids)
 591 {
 592         int i;
 593         struct commit *commit;
 594
 595         for (i = 0; i < oids->nr; i++) {
 596                 commit = lookup_commit(the_repository, &oids->list[i]);
 597                 if (commit)
 598                         commit->object.flags |= UNINTERESTING;
 599         }
 600
 601         /*
 602          * As this loop runs, oids->nr may grow, but not more
 603          * than the number of missing commits in the reachable
 604          * closure.
 605          */
 606         for (i = 0; i < oids->nr; i++) {
 607                 commit = lookup_commit(the_repository, &oids->list[i]);
 608
 609                 if (commit && !parse_commit(commit))
 610                         add_missing_parents(oids, commit);
 611         }
 612
 613         for (i = 0; i < oids->nr; i++) {
 614                 commit = lookup_commit(the_repository, &oids->list[i]);
 615
 616                 if (commit)
 617                         commit->object.flags &= ~UNINTERESTING;
 618         }
 619 }
 620
 621 static void compute_generation_numbers(struct packed_commit_list* commits)
 622 {
 623         int i;
 624         struct commit_list *list = NULL;
 625
 626         for (i = 0; i < commits->nr; i++) {
 627                 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
 628                     commits->list[i]->generation != GENERATION_NUMBER_ZERO)
 629                         continue;
 630
 631                 commit_list_insert(commits->list[i], &list);
 632                 while (list) {
 633                         struct commit *current = list->item;
 634                         struct commit_list *parent;
 635                         int all_parents_computed = 1;
 636                         uint32_t max_generation = 0;
 637
 638                         for (parent = current->parents; parent; parent = parent->next) {
 639                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 640                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 641                                         all_parents_computed = 0;
 642                                         commit_list_insert(parent->item, &list);
 643                                         break;
 644                                 } else if (parent->item->generation > max_generation) {
 645                                         max_generation = parent->item->generation;
 646                                 }
 647                         }
 648
 649                         if (all_parents_computed) {
 650                                 current->generation = max_generation + 1;
 651                                 pop_commit(&list);
 652
 653                                 if (current->generation > GENERATION_NUMBER_MAX)
 654                                         current->generation = GENERATION_NUMBER_MAX;
 655                         }
 656                 }
 657         }
 658 }
 659
 660 static int add_ref_to_list(const char *refname,
 661                            const struct object_id *oid,
 662                            int flags, void *cb_data)
 663 {
 664         struct string_list *list = (struct string_list *)cb_data;
 665
 666         string_list_append(list, oid_to_hex(oid));
 667         return 0;
 668 }
 669
 670 void write_commit_graph_reachable(const char *obj_dir, int append)
 671 {
 672         struct string_list list;
 673
 674         string_list_init(&list, 1);
 675         for_each_ref(add_ref_to_list, &list);
 676         write_commit_graph(obj_dir, NULL, &list, append);
 677 }
 678
 679 void write_commit_graph(const char *obj_dir,
 680                         struct string_list *pack_indexes,
 681                         struct string_list *commit_hex,
 682                         int append)
 683 {
 684         struct packed_oid_list oids;
 685         struct packed_commit_list commits;
 686         struct hashfile *f;
 687         uint32_t i, count_distinct = 0;
 688         char *graph_name;
 689         struct lock_file lk = LOCK_INIT;
 690         uint32_t chunk_ids[5];
 691         uint64_t chunk_offsets[5];
 692         int num_chunks;
 693         int num_extra_edges;
 694         struct commit_list *parent;
 695
 696         oids.nr = 0;
 697         oids.alloc = approximate_object_count() / 4;
 698
 699         if (append) {
 700                 prepare_commit_graph_one(obj_dir);
 701                 if (commit_graph)
 702                         oids.alloc += commit_graph->num_commits;
 703         }
 704
 705         if (oids.alloc < 1024)
 706                 oids.alloc = 1024;
 707         ALLOC_ARRAY(oids.list, oids.alloc);
 708
 709         if (append && commit_graph) {
 710                 for (i = 0; i < commit_graph->num_commits; i++) {
 711                         const unsigned char *hash = commit_graph->chunk_oid_lookup +
 712                                 commit_graph->hash_len * i;
 713                         hashcpy(oids.list[oids.nr++].hash, hash);
 714                 }
 715         }
 716
 717         if (pack_indexes) {
 718                 struct strbuf packname = STRBUF_INIT;
 719                 int dirlen;
 720                 strbuf_addf(&packname, "%s/pack/", obj_dir);
 721                 dirlen = packname.len;
 722                 for (i = 0; i < pack_indexes->nr; i++) {
 723                         struct packed_git *p;
 724                         strbuf_setlen(&packname, dirlen);
 725                         strbuf_addstr(&packname, pack_indexes->items[i].string);
 726                         p = add_packed_git(packname.buf, packname.len, 1);
 727                         if (!p)
 728                                 die("error adding pack %s", packname.buf);
 729                         if (open_pack_index(p))
 730                                 die("error opening index for %s", packname.buf);
 731                         for_each_object_in_pack(p, add_packed_commits, &oids);
 732                         close_pack(p);
 733                 }
 734                 strbuf_release(&packname);
 735         }
 736
 737         if (commit_hex) {
 738                 for (i = 0; i < commit_hex->nr; i++) {
 739                         const char *end;
 740                         struct object_id oid;
 741                         struct commit *result;
 742
 743                         if (commit_hex->items[i].string &&
 744                             parse_oid_hex(commit_hex->items[i].string, &oid, &end))
 745                                 continue;
 746
 747                         result = lookup_commit_reference_gently(the_repository, &oid, 1);
 748
 749                         if (result) {
 750                                 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
 751                                 oidcpy(&oids.list[oids.nr], &(result->object.oid));
 752                                 oids.nr++;
 753                         }
 754                 }
 755         }
 756
 757         if (!pack_indexes && !commit_hex)
 758                 for_each_packed_object(add_packed_commits, &oids, 0);
 759
 760         close_reachable(&oids);
 761
 762         QSORT(oids.list, oids.nr, commit_compare);
 763
 764         count_distinct = 1;
 765         for (i = 1; i < oids.nr; i++) {
 766                 if (oidcmp(&oids.list[i-1], &oids.list[i]))
 767                         count_distinct++;
 768         }
 769
 770         if (count_distinct >= GRAPH_PARENT_MISSING)
 771                 die(_("the commit graph format cannot write %d commits"), count_distinct);
 772
 773         commits.nr = 0;
 774         commits.alloc = count_distinct;
 775         ALLOC_ARRAY(commits.list, commits.alloc);
 776
 777         num_extra_edges = 0;
 778         for (i = 0; i < oids.nr; i++) {
 779                 int num_parents = 0;
 780                 if (i > 0 && !oidcmp(&oids.list[i-1], &oids.list[i]))
 781                         continue;
 782
 783                 commits.list[commits.nr] = lookup_commit(the_repository, &oids.list[i]);
 784                 parse_commit(commits.list[commits.nr]);
 785
 786                 for (parent = commits.list[commits.nr]->parents;
 787                      parent; parent = parent->next)
 788                         num_parents++;
 789
 790                 if (num_parents > 2)
 791                         num_extra_edges += num_parents - 1;
 792
 793                 commits.nr++;
 794         }
 795         num_chunks = num_extra_edges ? 4 : 3;
 796
 797         if (commits.nr >= GRAPH_PARENT_MISSING)
 798                 die(_("too many commits to write graph"));
 799
 800         compute_generation_numbers(&commits);
 801
 802         graph_name = get_commit_graph_filename(obj_dir);
 803         if (safe_create_leading_directories(graph_name))
 804                 die_errno(_("unable to create leading directories of %s"),
 805                           graph_name);
 806
 807         hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
 808         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 809
 810         hashwrite_be32(f, GRAPH_SIGNATURE);
 811
 812         hashwrite_u8(f, GRAPH_VERSION);
 813         hashwrite_u8(f, GRAPH_OID_VERSION);
 814         hashwrite_u8(f, num_chunks);
 815         hashwrite_u8(f, 0); /* unused padding byte */
 816
 817         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
 818         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
 819         chunk_ids[2] = GRAPH_CHUNKID_DATA;
 820         if (num_extra_edges)
 821                 chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
 822         else
 823                 chunk_ids[3] = 0;
 824         chunk_ids[4] = 0;
 825
 826         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
 827         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
 828         chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
 829         chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
 830         chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
 831
 832         for (i = 0; i <= num_chunks; i++) {
 833                 uint32_t chunk_write[3];
 834
 835                 chunk_write[0] = htonl(chunk_ids[i]);
 836                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
 837                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
 838                 hashwrite(f, chunk_write, 12);
 839         }
 840
 841         write_graph_chunk_fanout(f, commits.list, commits.nr);
 842         write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
 843         write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 844         write_graph_chunk_large_edges(f, commits.list, commits.nr);
 845
 846         close_commit_graph();
 847         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 848         commit_lock_file(&lk);
 849
 850         free(oids.list);
 851         oids.alloc = 0;
 852         oids.nr = 0;
 853 }
 854
 855 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
 856 static int verify_commit_graph_error;
 857
 858 static void graph_report(const char *fmt, ...)
 859 {
 860         va_list ap;
 861
 862         verify_commit_graph_error = 1;
 863         va_start(ap, fmt);
 864         vfprintf(stderr, fmt, ap);
 865         fprintf(stderr, "\n");
 866         va_end(ap);
 867 }
 868
 869 #define GENERATION_ZERO_EXISTS 1
 870 #define GENERATION_NUMBER_EXISTS 2
 871
 872 int verify_commit_graph(struct repository *r, struct commit_graph *g)
 873 {
 874         uint32_t i, cur_fanout_pos = 0;
 875         struct object_id prev_oid, cur_oid, checksum;
 876         int generation_zero = 0;
 877         struct hashfile *f;
 878         int devnull;
 879
 880         if (!g) {
 881                 graph_report("no commit-graph file loaded");
 882                 return 1;
 883         }
 884
 885         verify_commit_graph_error = 0;
 886
 887         if (!g->chunk_oid_fanout)
 888                 graph_report("commit-graph is missing the OID Fanout chunk");
 889         if (!g->chunk_oid_lookup)
 890                 graph_report("commit-graph is missing the OID Lookup chunk");
 891         if (!g->chunk_commit_data)
 892                 graph_report("commit-graph is missing the Commit Data chunk");
 893
 894         if (verify_commit_graph_error)
 895                 return verify_commit_graph_error;
 896
 897         devnull = open("/dev/null", O_WRONLY);
 898         f = hashfd(devnull, NULL);
 899         hashwrite(f, g->data, g->data_len - g->hash_len);
 900         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
 901         if (hashcmp(checksum.hash, g->data + g->data_len - g->hash_len)) {
 902                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
 903                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
 904         }
 905
 906         for (i = 0; i < g->num_commits; i++) {
 907                 struct commit *graph_commit;
 908
 909                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 910
 911                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
 912                         graph_report("commit-graph has incorrect OID order: %s then %s",
 913                                      oid_to_hex(&prev_oid),
 914                                      oid_to_hex(&cur_oid));
 915
 916                 oidcpy(&prev_oid, &cur_oid);
 917
 918                 while (cur_oid.hash[0] > cur_fanout_pos) {
 919                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
 920
 921                         if (i != fanout_value)
 922                                 graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
 923                                              cur_fanout_pos, fanout_value, i);
 924                         cur_fanout_pos++;
 925                 }
 926
 927                 graph_commit = lookup_commit(r, &cur_oid);
 928                 if (!parse_commit_in_graph_one(g, graph_commit))
 929                         graph_report("failed to parse %s from commit-graph",
 930                                      oid_to_hex(&cur_oid));
 931         }
 932
 933         while (cur_fanout_pos < 256) {
 934                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
 935
 936                 if (g->num_commits != fanout_value)
 937                         graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
 938                                      cur_fanout_pos, fanout_value, i);
 939
 940                 cur_fanout_pos++;
 941         }
 942
 943         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
 944                 return verify_commit_graph_error;
 945
 946         for (i = 0; i < g->num_commits; i++) {
 947                 struct commit *graph_commit, *odb_commit;
 948                 struct commit_list *graph_parents, *odb_parents;
 949                 uint32_t max_generation = 0;
 950
 951                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 952
 953                 graph_commit = lookup_commit(r, &cur_oid);
 954                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
 955                 if (parse_commit_internal(odb_commit, 0, 0)) {
 956                         graph_report("failed to parse %s from object database",
 957                                      oid_to_hex(&cur_oid));
 958                         continue;
 959                 }
 960
 961                 if (oidcmp(&get_commit_tree_in_graph_one(g, graph_commit)->object.oid,
 962                            get_commit_tree_oid(odb_commit)))
 963                         graph_report("root tree OID for commit %s in commit-graph is %s != %s",
 964                                      oid_to_hex(&cur_oid),
 965                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
 966                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
 967
 968                 graph_parents = graph_commit->parents;
 969                 odb_parents = odb_commit->parents;
 970
 971                 while (graph_parents) {
 972                         if (odb_parents == NULL) {
 973                                 graph_report("commit-graph parent list for commit %s is too long",
 974                                              oid_to_hex(&cur_oid));
 975                                 break;
 976                         }
 977
 978                         if (oidcmp(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
 979                                 graph_report("commit-graph parent for %s is %s != %s",
 980                                              oid_to_hex(&cur_oid),
 981                                              oid_to_hex(&graph_parents->item->object.oid),
 982                                              oid_to_hex(&odb_parents->item->object.oid));
 983
 984                         if (graph_parents->item->generation > max_generation)
 985                                 max_generation = graph_parents->item->generation;
 986
 987                         graph_parents = graph_parents->next;
 988                         odb_parents = odb_parents->next;
 989                 }
 990
 991                 if (odb_parents != NULL)
 992                         graph_report("commit-graph parent list for commit %s terminates early",
 993                                      oid_to_hex(&cur_oid));
 994
 995                 if (!graph_commit->generation) {
 996                         if (generation_zero == GENERATION_NUMBER_EXISTS)
 997                                 graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
 998                                              oid_to_hex(&cur_oid));
 999                         generation_zero = GENERATION_ZERO_EXISTS;
1000                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1001                         graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
1002                                      oid_to_hex(&cur_oid));
1003
1004                 if (generation_zero == GENERATION_ZERO_EXISTS)
1005                         continue;
1006
1007                 /*
1008                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1009                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1010                  * extra logic in the following condition.
1011                  */
1012                 if (max_generation == GENERATION_NUMBER_MAX)
1013                         max_generation--;
1014
1015                 if (graph_commit->generation != max_generation + 1)
1016                         graph_report("commit-graph generation for commit %s is %u != %u",
1017                                      oid_to_hex(&cur_oid),
1018                                      graph_commit->generation,
1019                                      max_generation + 1);
1020
1021                 if (graph_commit->date != odb_commit->date)
1022                         graph_report("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime,
1023                                      oid_to_hex(&cur_oid),
1024                                      graph_commit->date,
1025                                      odb_commit->date);
1026         }
1027
1028         return verify_commit_graph_error;
1029 }