shallow.c

   1 #include "cache.h"
   2 #include "repository.h"
   3 #include "tempfile.h"
   4 #include "lockfile.h"
   5 #include "object-store.h"
   6 #include "commit.h"
   7 #include "tag.h"
   8 #include "pkt-line.h"
   9 #include "remote.h"
  10 #include "refs.h"
  11 #include "oid-array.h"
  12 #include "diff.h"
  13 #include "revision.h"
  14 #include "commit-slab.h"
  15 #include "list-objects.h"
  16 #include "commit-reach.h"
  17 #include "shallow.h"
  18
  19 void set_alternate_shallow_file(struct repository *r, const char *path, int override)
  20 {
  21         if (r->parsed_objects->is_shallow != -1)
  22                 BUG("is_repository_shallow must not be called before set_alternate_shallow_file");
  23         if (r->parsed_objects->alternate_shallow_file && !override)
  24                 return;
  25         free(r->parsed_objects->alternate_shallow_file);
  26         r->parsed_objects->alternate_shallow_file = xstrdup_or_null(path);
  27 }
  28
  29 int register_shallow(struct repository *r, const struct object_id *oid)
  30 {
  31         struct commit_graft *graft =
  32                 xmalloc(sizeof(struct commit_graft));
  33         struct commit *commit = lookup_commit(the_repository, oid);
  34
  35         oidcpy(&graft->oid, oid);
  36         graft->nr_parent = -1;
  37         if (commit && commit->object.parsed)
  38                 commit->parents = NULL;
  39         return register_commit_graft(r, graft, 0);
  40 }
  41
  42 int unregister_shallow(const struct object_id *oid)
  43 {
  44         int pos = commit_graft_pos(the_repository, oid);
  45         if (pos < 0)
  46                 return -1;
  47         if (pos + 1 < the_repository->parsed_objects->grafts_nr)
  48                 MOVE_ARRAY(the_repository->parsed_objects->grafts + pos,
  49                            the_repository->parsed_objects->grafts + pos + 1,
  50                            the_repository->parsed_objects->grafts_nr - pos - 1);
  51         the_repository->parsed_objects->grafts_nr--;
  52         return 0;
  53 }
  54
  55 int is_repository_shallow(struct repository *r)
  56 {
  57         FILE *fp;
  58         char buf[1024];
  59         const char *path = r->parsed_objects->alternate_shallow_file;
  60
  61         if (r->parsed_objects->is_shallow >= 0)
  62                 return r->parsed_objects->is_shallow;
  63
  64         if (!path)
  65                 path = git_path_shallow(r);
  66         /*
  67          * fetch-pack sets '--shallow-file ""' as an indicator that no
  68          * shallow file should be used. We could just open it and it
  69          * will likely fail. But let's do an explicit check instead.
  70          */
  71         if (!*path || (fp = fopen(path, "r")) == NULL) {
  72                 stat_validity_clear(r->parsed_objects->shallow_stat);
  73                 r->parsed_objects->is_shallow = 0;
  74                 return r->parsed_objects->is_shallow;
  75         }
  76         stat_validity_update(r->parsed_objects->shallow_stat, fileno(fp));
  77         r->parsed_objects->is_shallow = 1;
  78
  79         while (fgets(buf, sizeof(buf), fp)) {
  80                 struct object_id oid;
  81                 if (get_oid_hex(buf, &oid))
  82                         die("bad shallow line: %s", buf);
  83                 register_shallow(r, &oid);
  84         }
  85         fclose(fp);
  86         return r->parsed_objects->is_shallow;
  87 }
  88
  89 static void reset_repository_shallow(struct repository *r)
  90 {
  91         r->parsed_objects->is_shallow = -1;
  92         stat_validity_clear(r->parsed_objects->shallow_stat);
  93         reset_commit_grafts(r);
  94 }
  95
  96 int commit_shallow_file(struct repository *r, struct shallow_lock *lk)
  97 {
  98         int res = commit_lock_file(&lk->lock);
  99         reset_repository_shallow(r);
 100
 101         /*
 102          * Update in-memory data structures with the new shallow information,
 103          * including unparsing all commits that now have grafts.
 104          */
 105         is_repository_shallow(r);
 106
 107         return res;
 108 }
 109
 110 void rollback_shallow_file(struct repository *r, struct shallow_lock *lk)
 111 {
 112         rollback_lock_file(&lk->lock);
 113         reset_repository_shallow(r);
 114 }
 115
 116 /*
 117  * TODO: use "int" elemtype instead of "int *" when/if commit-slab
 118  * supports a "valid" flag.
 119  */
 120 define_commit_slab(commit_depth, int *);
 121 static void free_depth_in_slab(int **ptr)
 122 {
 123         FREE_AND_NULL(*ptr);
 124 }
 125 struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
 126                 int shallow_flag, int not_shallow_flag)
 127 {
 128         int i = 0, cur_depth = 0;
 129         struct commit_list *result = NULL;
 130         struct object_array stack = OBJECT_ARRAY_INIT;
 131         struct commit *commit = NULL;
 132         struct commit_graft *graft;
 133         struct commit_depth depths;
 134
 135         init_commit_depth(&depths);
 136         while (commit || i < heads->nr || stack.nr) {
 137                 struct commit_list *p;
 138                 if (!commit) {
 139                         if (i < heads->nr) {
 140                                 int **depth_slot;
 141                                 commit = (struct commit *)
 142                                         deref_tag(the_repository,
 143                                                   heads->objects[i++].item,
 144                                                   NULL, 0);
 145                                 if (!commit || commit->object.type != OBJ_COMMIT) {
 146                                         commit = NULL;
 147                                         continue;
 148                                 }
 149                                 depth_slot = commit_depth_at(&depths, commit);
 150                                 if (!*depth_slot)
 151                                         *depth_slot = xmalloc(sizeof(int));
 152                                 **depth_slot = 0;
 153                                 cur_depth = 0;
 154                         } else {
 155                                 commit = (struct commit *)
 156                                         object_array_pop(&stack);
 157                                 cur_depth = **commit_depth_at(&depths, commit);
 158                         }
 159                 }
 160                 parse_commit_or_die(commit);
 161                 cur_depth++;
 162                 if ((depth != INFINITE_DEPTH && cur_depth >= depth) ||
 163                     (is_repository_shallow(the_repository) && !commit->parents &&
 164                      (graft = lookup_commit_graft(the_repository, &commit->object.oid)) != NULL &&
 165                      graft->nr_parent < 0)) {
 166                         commit_list_insert(commit, &result);
 167                         commit->object.flags |= shallow_flag;
 168                         commit = NULL;
 169                         continue;
 170                 }
 171                 commit->object.flags |= not_shallow_flag;
 172                 for (p = commit->parents, commit = NULL; p; p = p->next) {
 173                         int **depth_slot = commit_depth_at(&depths, p->item);
 174                         if (!*depth_slot) {
 175                                 *depth_slot = xmalloc(sizeof(int));
 176                                 **depth_slot = cur_depth;
 177                         } else {
 178                                 if (cur_depth >= **depth_slot)
 179                                         continue;
 180                                 **depth_slot = cur_depth;
 181                         }
 182                         if (p->next)
 183                                 add_object_array(&p->item->object,
 184                                                 NULL, &stack);
 185                         else {
 186                                 commit = p->item;
 187                                 cur_depth = **commit_depth_at(&depths, commit);
 188                         }
 189                 }
 190         }
 191         deep_clear_commit_depth(&depths, free_depth_in_slab);
 192
 193         return result;
 194 }
 195
 196 static void show_commit(struct commit *commit, void *data)
 197 {
 198         commit_list_insert(commit, data);
 199 }
 200
 201 /*
 202  * Given rev-list arguments, run rev-list. All reachable commits
 203  * except border ones are marked with not_shallow_flag. Border commits
 204  * are marked with shallow_flag. The list of border/shallow commits
 205  * are also returned.
 206  */
 207 struct commit_list *get_shallow_commits_by_rev_list(int ac, const char **av,
 208                                                     int shallow_flag,
 209                                                     int not_shallow_flag)
 210 {
 211         struct commit_list *result = NULL, *p;
 212         struct commit_list *not_shallow_list = NULL;
 213         struct rev_info revs;
 214         int both_flags = shallow_flag | not_shallow_flag;
 215
 216         /*
 217          * SHALLOW (excluded) and NOT_SHALLOW (included) should not be
 218          * set at this point. But better be safe than sorry.
 219          */
 220         clear_object_flags(both_flags);
 221
 222         is_repository_shallow(the_repository); /* make sure shallows are read */
 223
 224         repo_init_revisions(the_repository, &revs, NULL);
 225         save_commit_buffer = 0;
 226         setup_revisions(ac, av, &revs, NULL);
 227
 228         if (prepare_revision_walk(&revs))
 229                 die("revision walk setup failed");
 230         traverse_commit_list(&revs, show_commit, NULL, &not_shallow_list);
 231
 232         if (!not_shallow_list)
 233                 die("no commits selected for shallow requests");
 234
 235         /* Mark all reachable commits as NOT_SHALLOW */
 236         for (p = not_shallow_list; p; p = p->next)
 237                 p->item->object.flags |= not_shallow_flag;
 238
 239         /*
 240          * mark border commits SHALLOW + NOT_SHALLOW.
 241          * We cannot clear NOT_SHALLOW right now. Imagine border
 242          * commit A is processed first, then commit B, whose parent is
 243          * A, later. If NOT_SHALLOW on A is cleared at step 1, B
 244          * itself is considered border at step 2, which is incorrect.
 245          */
 246         for (p = not_shallow_list; p; p = p->next) {
 247                 struct commit *c = p->item;
 248                 struct commit_list *parent;
 249
 250                 if (parse_commit(c))
 251                         die("unable to parse commit %s",
 252                             oid_to_hex(&c->object.oid));
 253
 254                 for (parent = c->parents; parent; parent = parent->next)
 255                         if (!(parent->item->object.flags & not_shallow_flag)) {
 256                                 c->object.flags |= shallow_flag;
 257                                 commit_list_insert(c, &result);
 258                                 break;
 259                         }
 260         }
 261         free_commit_list(not_shallow_list);
 262
 263         /*
 264          * Now we can clean up NOT_SHALLOW on border commits. Having
 265          * both flags set can confuse the caller.
 266          */
 267         for (p = result; p; p = p->next) {
 268                 struct object *o = &p->item->object;
 269                 if ((o->flags & both_flags) == both_flags)
 270                         o->flags &= ~not_shallow_flag;
 271         }
 272         release_revisions(&revs);
 273         return result;
 274 }
 275
 276 static void check_shallow_file_for_update(struct repository *r)
 277 {
 278         if (r->parsed_objects->is_shallow == -1)
 279                 BUG("shallow must be initialized by now");
 280
 281         if (!stat_validity_check(r->parsed_objects->shallow_stat,
 282                                  git_path_shallow(r)))
 283                 die("shallow file has changed since we read it");
 284 }
 285
 286 #define SEEN_ONLY 1
 287 #define VERBOSE   2
 288 #define QUICK 4
 289
 290 struct write_shallow_data {
 291         struct strbuf *out;
 292         int use_pack_protocol;
 293         int count;
 294         unsigned flags;
 295 };
 296
 297 static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
 298 {
 299         struct write_shallow_data *data = cb_data;
 300         const char *hex = oid_to_hex(&graft->oid);
 301         if (graft->nr_parent != -1)
 302                 return 0;
 303         if (data->flags & QUICK) {
 304                 if (!has_object_file(&graft->oid))
 305                         return 0;
 306         } else if (data->flags & SEEN_ONLY) {
 307                 struct commit *c = lookup_commit(the_repository, &graft->oid);
 308                 if (!c || !(c->object.flags & SEEN)) {
 309                         if (data->flags & VERBOSE)
 310                                 printf("Removing %s from .git/shallow\n",
 311                                        oid_to_hex(&c->object.oid));
 312                         return 0;
 313                 }
 314         }
 315         data->count++;
 316         if (data->use_pack_protocol)
 317                 packet_buf_write(data->out, "shallow %s", hex);
 318         else {
 319                 strbuf_addstr(data->out, hex);
 320                 strbuf_addch(data->out, '\n');
 321         }
 322         return 0;
 323 }
 324
 325 static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
 326                                    const struct oid_array *extra,
 327                                    unsigned flags)
 328 {
 329         struct write_shallow_data data;
 330         int i;
 331         data.out = out;
 332         data.use_pack_protocol = use_pack_protocol;
 333         data.count = 0;
 334         data.flags = flags;
 335         for_each_commit_graft(write_one_shallow, &data);
 336         if (!extra)
 337                 return data.count;
 338         for (i = 0; i < extra->nr; i++) {
 339                 strbuf_addstr(out, oid_to_hex(extra->oid + i));
 340                 strbuf_addch(out, '\n');
 341                 data.count++;
 342         }
 343         return data.count;
 344 }
 345
 346 int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
 347                           const struct oid_array *extra)
 348 {
 349         return write_shallow_commits_1(out, use_pack_protocol, extra, 0);
 350 }
 351
 352 const char *setup_temporary_shallow(const struct oid_array *extra)
 353 {
 354         struct tempfile *temp;
 355         struct strbuf sb = STRBUF_INIT;
 356
 357         if (write_shallow_commits(&sb, 0, extra)) {
 358                 temp = xmks_tempfile(git_path("shallow_XXXXXX"));
 359
 360                 if (write_in_full(temp->fd, sb.buf, sb.len) < 0 ||
 361                     close_tempfile_gently(temp) < 0)
 362                         die_errno("failed to write to %s",
 363                                   get_tempfile_path(temp));
 364                 strbuf_release(&sb);
 365                 return get_tempfile_path(temp);
 366         }
 367         /*
 368          * is_repository_shallow() sees empty string as "no shallow
 369          * file".
 370          */
 371         return "";
 372 }
 373
 374 void setup_alternate_shallow(struct shallow_lock *shallow_lock,
 375                              const char **alternate_shallow_file,
 376                              const struct oid_array *extra)
 377 {
 378         struct strbuf sb = STRBUF_INIT;
 379         int fd;
 380
 381         fd = hold_lock_file_for_update(&shallow_lock->lock,
 382                                        git_path_shallow(the_repository),
 383                                        LOCK_DIE_ON_ERROR);
 384         check_shallow_file_for_update(the_repository);
 385         if (write_shallow_commits(&sb, 0, extra)) {
 386                 if (write_in_full(fd, sb.buf, sb.len) < 0)
 387                         die_errno("failed to write to %s",
 388                                   get_lock_file_path(&shallow_lock->lock));
 389                 *alternate_shallow_file = get_lock_file_path(&shallow_lock->lock);
 390         } else
 391                 /*
 392                  * is_repository_shallow() sees empty string as "no
 393                  * shallow file".
 394                  */
 395                 *alternate_shallow_file = "";
 396         strbuf_release(&sb);
 397 }
 398
 399 static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
 400 {
 401         int fd = *(int *)cb;
 402         if (graft->nr_parent == -1)
 403                 packet_write_fmt(fd, "shallow %s\n", oid_to_hex(&graft->oid));
 404         return 0;
 405 }
 406
 407 void advertise_shallow_grafts(int fd)
 408 {
 409         if (!is_repository_shallow(the_repository))
 410                 return;
 411         for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
 412 }
 413
 414 /*
 415  * mark_reachable_objects() should have been run prior to this and all
 416  * reachable commits marked as "SEEN", except when quick_prune is non-zero,
 417  * in which case lines are excised from the shallow file if they refer to
 418  * commits that do not exist (any longer).
 419  */
 420 void prune_shallow(unsigned options)
 421 {
 422         struct shallow_lock shallow_lock = SHALLOW_LOCK_INIT;
 423         struct strbuf sb = STRBUF_INIT;
 424         unsigned flags = SEEN_ONLY;
 425         int fd;
 426
 427         if (options & PRUNE_QUICK)
 428                 flags |= QUICK;
 429
 430         if (options & PRUNE_SHOW_ONLY) {
 431                 flags |= VERBOSE;
 432                 write_shallow_commits_1(&sb, 0, NULL, flags);
 433                 strbuf_release(&sb);
 434                 return;
 435         }
 436         fd = hold_lock_file_for_update(&shallow_lock.lock,
 437                                        git_path_shallow(the_repository),
 438                                        LOCK_DIE_ON_ERROR);
 439         check_shallow_file_for_update(the_repository);
 440         if (write_shallow_commits_1(&sb, 0, NULL, flags)) {
 441                 if (write_in_full(fd, sb.buf, sb.len) < 0)
 442                         die_errno("failed to write to %s",
 443                                   get_lock_file_path(&shallow_lock.lock));
 444                 commit_shallow_file(the_repository, &shallow_lock);
 445         } else {
 446                 unlink(git_path_shallow(the_repository));
 447                 rollback_shallow_file(the_repository, &shallow_lock);
 448         }
 449         strbuf_release(&sb);
 450 }
 451
 452 struct trace_key trace_shallow = TRACE_KEY_INIT(SHALLOW);
 453
 454 /*
 455  * Step 1, split sender shallow commits into "ours" and "theirs"
 456  * Step 2, clean "ours" based on .git/shallow
 457  */
 458 void prepare_shallow_info(struct shallow_info *info, struct oid_array *sa)
 459 {
 460         int i;
 461         trace_printf_key(&trace_shallow, "shallow: prepare_shallow_info\n");
 462         memset(info, 0, sizeof(*info));
 463         info->shallow = sa;
 464         if (!sa)
 465                 return;
 466         ALLOC_ARRAY(info->ours, sa->nr);
 467         ALLOC_ARRAY(info->theirs, sa->nr);
 468         for (i = 0; i < sa->nr; i++) {
 469                 if (has_object_file(sa->oid + i)) {
 470                         struct commit_graft *graft;
 471                         graft = lookup_commit_graft(the_repository,
 472                                                     &sa->oid[i]);
 473                         if (graft && graft->nr_parent < 0)
 474                                 continue;
 475                         info->ours[info->nr_ours++] = i;
 476                 } else
 477                         info->theirs[info->nr_theirs++] = i;
 478         }
 479 }
 480
 481 void clear_shallow_info(struct shallow_info *info)
 482 {
 483         free(info->ours);
 484         free(info->theirs);
 485 }
 486
 487 /* Step 4, remove non-existent ones in "theirs" after getting the pack */
 488
 489 void remove_nonexistent_theirs_shallow(struct shallow_info *info)
 490 {
 491         struct object_id *oid = info->shallow->oid;
 492         int i, dst;
 493         trace_printf_key(&trace_shallow, "shallow: remove_nonexistent_theirs_shallow\n");
 494         for (i = dst = 0; i < info->nr_theirs; i++) {
 495                 if (i != dst)
 496                         info->theirs[dst] = info->theirs[i];
 497                 if (has_object_file(oid + info->theirs[i]))
 498                         dst++;
 499         }
 500         info->nr_theirs = dst;
 501 }
 502
 503 define_commit_slab(ref_bitmap, uint32_t *);
 504
 505 #define POOL_SIZE (512 * 1024)
 506
 507 struct paint_info {
 508         struct ref_bitmap ref_bitmap;
 509         unsigned nr_bits;
 510         char **pools;
 511         char *free, *end;
 512         unsigned pool_count;
 513 };
 514
 515 static uint32_t *paint_alloc(struct paint_info *info)
 516 {
 517         unsigned nr = DIV_ROUND_UP(info->nr_bits, 32);
 518         unsigned size = nr * sizeof(uint32_t);
 519         void *p;
 520         if (!info->pool_count || size > info->end - info->free) {
 521                 if (size > POOL_SIZE)
 522                         BUG("pool size too small for %d in paint_alloc()",
 523                             size);
 524                 info->pool_count++;
 525                 REALLOC_ARRAY(info->pools, info->pool_count);
 526                 info->free = xmalloc(POOL_SIZE);
 527                 info->pools[info->pool_count - 1] = info->free;
 528                 info->end = info->free + POOL_SIZE;
 529         }
 530         p = info->free;
 531         info->free += size;
 532         return p;
 533 }
 534
 535 /*
 536  * Given a commit SHA-1, walk down to parents until either SEEN,
 537  * UNINTERESTING or BOTTOM is hit. Set the id-th bit in ref_bitmap for
 538  * all walked commits.
 539  */
 540 static void paint_down(struct paint_info *info, const struct object_id *oid,
 541                        unsigned int id)
 542 {
 543         unsigned int i, nr;
 544         struct commit_list *head = NULL;
 545         int bitmap_nr = DIV_ROUND_UP(info->nr_bits, 32);
 546         size_t bitmap_size = st_mult(sizeof(uint32_t), bitmap_nr);
 547         struct commit *c = lookup_commit_reference_gently(the_repository, oid,
 548                                                           1);
 549         uint32_t *tmp; /* to be freed before return */
 550         uint32_t *bitmap;
 551
 552         if (!c)
 553                 return;
 554
 555         tmp = xmalloc(bitmap_size);
 556         bitmap = paint_alloc(info);
 557         memset(bitmap, 0, bitmap_size);
 558         bitmap[id / 32] |= (1U << (id % 32));
 559         commit_list_insert(c, &head);
 560         while (head) {
 561                 struct commit_list *p;
 562                 struct commit *c = pop_commit(&head);
 563                 uint32_t **refs = ref_bitmap_at(&info->ref_bitmap, c);
 564
 565                 /* XXX check "UNINTERESTING" from pack bitmaps if available */
 566                 if (c->object.flags & (SEEN | UNINTERESTING))
 567                         continue;
 568                 else
 569                         c->object.flags |= SEEN;
 570
 571                 if (!*refs)
 572                         *refs = bitmap;
 573                 else {
 574                         memcpy(tmp, *refs, bitmap_size);
 575                         for (i = 0; i < bitmap_nr; i++)
 576                                 tmp[i] |= bitmap[i];
 577                         if (memcmp(tmp, *refs, bitmap_size)) {
 578                                 *refs = paint_alloc(info);
 579                                 memcpy(*refs, tmp, bitmap_size);
 580                         }
 581                 }
 582
 583                 if (c->object.flags & BOTTOM)
 584                         continue;
 585
 586                 if (parse_commit(c))
 587                         die("unable to parse commit %s",
 588                             oid_to_hex(&c->object.oid));
 589
 590                 for (p = c->parents; p; p = p->next) {
 591                         if (p->item->object.flags & SEEN)
 592                                 continue;
 593                         commit_list_insert(p->item, &head);
 594                 }
 595         }
 596
 597         nr = get_max_object_index();
 598         for (i = 0; i < nr; i++) {
 599                 struct object *o = get_indexed_object(i);
 600                 if (o && o->type == OBJ_COMMIT)
 601                         o->flags &= ~SEEN;
 602         }
 603
 604         free(tmp);
 605 }
 606
 607 static int mark_uninteresting(const char *refname UNUSED,
 608                               const struct object_id *oid,
 609                               int flags UNUSED,
 610                               void *cb_data UNUSED)
 611 {
 612         struct commit *commit = lookup_commit_reference_gently(the_repository,
 613                                                                oid, 1);
 614         if (!commit)
 615                 return 0;
 616         commit->object.flags |= UNINTERESTING;
 617         mark_parents_uninteresting(NULL, commit);
 618         return 0;
 619 }
 620
 621 static void post_assign_shallow(struct shallow_info *info,
 622                                 struct ref_bitmap *ref_bitmap,
 623                                 int *ref_status);
 624 /*
 625  * Step 6(+7), associate shallow commits with new refs
 626  *
 627  * info->ref must be initialized before calling this function.
 628  *
 629  * If used is not NULL, it's an array of info->shallow->nr
 630  * bitmaps. The n-th bit set in the m-th bitmap if ref[n] needs the
 631  * m-th shallow commit from info->shallow.
 632  *
 633  * If used is NULL, "ours" and "theirs" are updated. And if ref_status
 634  * is not NULL it's an array of ref->nr ints. ref_status[i] is true if
 635  * the ref needs some shallow commits from either info->ours or
 636  * info->theirs.
 637  */
 638 void assign_shallow_commits_to_refs(struct shallow_info *info,
 639                                     uint32_t **used, int *ref_status)
 640 {
 641         struct object_id *oid = info->shallow->oid;
 642         struct oid_array *ref = info->ref;
 643         unsigned int i, nr;
 644         int *shallow, nr_shallow = 0;
 645         struct paint_info pi;
 646
 647         trace_printf_key(&trace_shallow, "shallow: assign_shallow_commits_to_refs\n");
 648         ALLOC_ARRAY(shallow, info->nr_ours + info->nr_theirs);
 649         for (i = 0; i < info->nr_ours; i++)
 650                 shallow[nr_shallow++] = info->ours[i];
 651         for (i = 0; i < info->nr_theirs; i++)
 652                 shallow[nr_shallow++] = info->theirs[i];
 653
 654         /*
 655          * Prepare the commit graph to track what refs can reach what
 656          * (new) shallow commits.
 657          */
 658         nr = get_max_object_index();
 659         for (i = 0; i < nr; i++) {
 660                 struct object *o = get_indexed_object(i);
 661                 if (!o || o->type != OBJ_COMMIT)
 662                         continue;
 663
 664                 o->flags &= ~(UNINTERESTING | BOTTOM | SEEN);
 665         }
 666
 667         memset(&pi, 0, sizeof(pi));
 668         init_ref_bitmap(&pi.ref_bitmap);
 669         pi.nr_bits = ref->nr;
 670
 671         /*
 672          * "--not --all" to cut short the traversal if new refs
 673          * connect to old refs. If not (e.g. force ref updates) it'll
 674          * have to go down to the current shallow commits.
 675          */
 676         head_ref(mark_uninteresting, NULL);
 677         for_each_ref(mark_uninteresting, NULL);
 678
 679         /* Mark potential bottoms so we won't go out of bound */
 680         for (i = 0; i < nr_shallow; i++) {
 681                 struct commit *c = lookup_commit(the_repository,
 682                                                  &oid[shallow[i]]);
 683                 c->object.flags |= BOTTOM;
 684         }
 685
 686         for (i = 0; i < ref->nr; i++)
 687                 paint_down(&pi, ref->oid + i, i);
 688
 689         if (used) {
 690                 int bitmap_size = DIV_ROUND_UP(pi.nr_bits, 32) * sizeof(uint32_t);
 691                 memset(used, 0, sizeof(*used) * info->shallow->nr);
 692                 for (i = 0; i < nr_shallow; i++) {
 693                         const struct commit *c = lookup_commit(the_repository,
 694                                                                &oid[shallow[i]]);
 695                         uint32_t **map = ref_bitmap_at(&pi.ref_bitmap, c);
 696                         if (*map)
 697                                 used[shallow[i]] = xmemdupz(*map, bitmap_size);
 698                 }
 699                 /*
 700                  * unreachable shallow commits are not removed from
 701                  * "ours" and "theirs". The user is supposed to run
 702                  * step 7 on every ref separately and not trust "ours"
 703                  * and "theirs" any more.
 704                  */
 705         } else
 706                 post_assign_shallow(info, &pi.ref_bitmap, ref_status);
 707
 708         clear_ref_bitmap(&pi.ref_bitmap);
 709         for (i = 0; i < pi.pool_count; i++)
 710                 free(pi.pools[i]);
 711         free(pi.pools);
 712         free(shallow);
 713 }
 714
 715 struct commit_array {
 716         struct commit **commits;
 717         int nr, alloc;
 718 };
 719
 720 static int add_ref(const char *refname UNUSED,
 721                    const struct object_id *oid,
 722                    int flags UNUSED,
 723                    void *cb_data)
 724 {
 725         struct commit_array *ca = cb_data;
 726         ALLOC_GROW(ca->commits, ca->nr + 1, ca->alloc);
 727         ca->commits[ca->nr] = lookup_commit_reference_gently(the_repository,
 728                                                              oid, 1);
 729         if (ca->commits[ca->nr])
 730                 ca->nr++;
 731         return 0;
 732 }
 733
 734 static void update_refstatus(int *ref_status, int nr, uint32_t *bitmap)
 735 {
 736         unsigned int i;
 737         if (!ref_status)
 738                 return;
 739         for (i = 0; i < nr; i++)
 740                 if (bitmap[i / 32] & (1U << (i % 32)))
 741                         ref_status[i]++;
 742 }
 743
 744 /*
 745  * Step 7, reachability test on "ours" at commit level
 746  */
 747 static void post_assign_shallow(struct shallow_info *info,
 748                                 struct ref_bitmap *ref_bitmap,
 749                                 int *ref_status)
 750 {
 751         struct object_id *oid = info->shallow->oid;
 752         struct commit *c;
 753         uint32_t **bitmap;
 754         int dst, i, j;
 755         int bitmap_nr = DIV_ROUND_UP(info->ref->nr, 32);
 756         struct commit_array ca;
 757
 758         trace_printf_key(&trace_shallow, "shallow: post_assign_shallow\n");
 759         if (ref_status)
 760                 memset(ref_status, 0, sizeof(*ref_status) * info->ref->nr);
 761
 762         /* Remove unreachable shallow commits from "theirs" */
 763         for (i = dst = 0; i < info->nr_theirs; i++) {
 764                 if (i != dst)
 765                         info->theirs[dst] = info->theirs[i];
 766                 c = lookup_commit(the_repository, &oid[info->theirs[i]]);
 767                 bitmap = ref_bitmap_at(ref_bitmap, c);
 768                 if (!*bitmap)
 769                         continue;
 770                 for (j = 0; j < bitmap_nr; j++)
 771                         if (bitmap[0][j]) {
 772                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
 773                                 dst++;
 774                                 break;
 775                         }
 776         }
 777         info->nr_theirs = dst;
 778
 779         memset(&ca, 0, sizeof(ca));
 780         head_ref(add_ref, &ca);
 781         for_each_ref(add_ref, &ca);
 782
 783         /* Remove unreachable shallow commits from "ours" */
 784         for (i = dst = 0; i < info->nr_ours; i++) {
 785                 if (i != dst)
 786                         info->ours[dst] = info->ours[i];
 787                 c = lookup_commit(the_repository, &oid[info->ours[i]]);
 788                 bitmap = ref_bitmap_at(ref_bitmap, c);
 789                 if (!*bitmap)
 790                         continue;
 791                 for (j = 0; j < bitmap_nr; j++)
 792                         if (bitmap[0][j] &&
 793                             /* Step 7, reachability test at commit level */
 794                             !in_merge_bases_many(c, ca.nr, ca.commits)) {
 795                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
 796                                 dst++;
 797                                 break;
 798                         }
 799         }
 800         info->nr_ours = dst;
 801
 802         free(ca.commits);
 803 }
 804
 805 /* (Delayed) step 7, reachability test at commit level */
 806 int delayed_reachability_test(struct shallow_info *si, int c)
 807 {
 808         if (si->need_reachability_test[c]) {
 809                 struct commit *commit = lookup_commit(the_repository,
 810                                                       &si->shallow->oid[c]);
 811
 812                 if (!si->commits) {
 813                         struct commit_array ca;
 814
 815                         memset(&ca, 0, sizeof(ca));
 816                         head_ref(add_ref, &ca);
 817                         for_each_ref(add_ref, &ca);
 818                         si->commits = ca.commits;
 819                         si->nr_commits = ca.nr;
 820                 }
 821
 822                 si->reachable[c] = in_merge_bases_many(commit,
 823                                                        si->nr_commits,
 824                                                        si->commits);
 825                 si->need_reachability_test[c] = 0;
 826         }
 827         return si->reachable[c];
 828 }