git.oblomov.eu Git - git/blob - revision.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "blob.h"
   4 #include "tree.h"
   5 #include "commit.h"
   6 #include "diff.h"
   7 #include "refs.h"
   8 #include "revision.h"
   9 #include "grep.h"
  10 #include "reflog-walk.h"
  11 #include "patch-ids.h"
  12
  13 static char *path_name(struct name_path *path, const char *name)
  14 {
  15         struct name_path *p;
  16         char *n, *m;
  17         int nlen = strlen(name);
  18         int len = nlen + 1;
  19
  20         for (p = path; p; p = p->up) {
  21                 if (p->elem_len)
  22                         len += p->elem_len + 1;
  23         }
  24         n = xmalloc(len);
  25         m = n + len - (nlen + 1);
  26         strcpy(m, name);
  27         for (p = path; p; p = p->up) {
  28                 if (p->elem_len) {
  29                         m -= p->elem_len + 1;
  30                         memcpy(m, p->elem, p->elem_len);
  31                         m[p->elem_len] = '/';
  32                 }
  33         }
  34         return n;
  35 }
  36
  37 void add_object(struct object *obj,
  38                 struct object_array *p,
  39                 struct name_path *path,
  40                 const char *name)
  41 {
  42         add_object_array(obj, path_name(path, name), p);
  43 }
  44
  45 static void mark_blob_uninteresting(struct blob *blob)
  46 {
  47         if (blob->object.flags & UNINTERESTING)
  48                 return;
  49         blob->object.flags |= UNINTERESTING;
  50 }
  51
  52 void mark_tree_uninteresting(struct tree *tree)
  53 {
  54         struct tree_desc desc;
  55         struct name_entry entry;
  56         struct object *obj = &tree->object;
  57
  58         if (obj->flags & UNINTERESTING)
  59                 return;
  60         obj->flags |= UNINTERESTING;
  61         if (!has_sha1_file(obj->sha1))
  62                 return;
  63         if (parse_tree(tree) < 0)
  64                 die("bad tree %s", sha1_to_hex(obj->sha1));
  65
  66         init_tree_desc(&desc, tree->buffer, tree->size);
  67         while (tree_entry(&desc, &entry)) {
  68                 if (S_ISDIR(entry.mode))
  69                         mark_tree_uninteresting(lookup_tree(entry.sha1));
  70                 else
  71                         mark_blob_uninteresting(lookup_blob(entry.sha1));
  72         }
  73
  74         /*
  75          * We don't care about the tree any more
  76          * after it has been marked uninteresting.
  77          */
  78         free(tree->buffer);
  79         tree->buffer = NULL;
  80 }
  81
  82 void mark_parents_uninteresting(struct commit *commit)
  83 {
  84         struct commit_list *parents = commit->parents;
  85
  86         while (parents) {
  87                 struct commit *commit = parents->item;
  88                 if (!(commit->object.flags & UNINTERESTING)) {
  89                         commit->object.flags |= UNINTERESTING;
  90
  91                         /*
  92                          * Normally we haven't parsed the parent
  93                          * yet, so we won't have a parent of a parent
  94                          * here. However, it may turn out that we've
  95                          * reached this commit some other way (where it
  96                          * wasn't uninteresting), in which case we need
  97                          * to mark its parents recursively too..
  98                          */
  99                         if (commit->parents)
 100                                 mark_parents_uninteresting(commit);
 101                 }
 102
 103                 /*
 104                  * A missing commit is ok iff its parent is marked
 105                  * uninteresting.
 106                  *
 107                  * We just mark such a thing parsed, so that when
 108                  * it is popped next time around, we won't be trying
 109                  * to parse it and get an error.
 110                  */
 111                 if (!has_sha1_file(commit->object.sha1))
 112                         commit->object.parsed = 1;
 113                 parents = parents->next;
 114         }
 115 }
 116
 117 void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
 118 {
 119         if (revs->no_walk && (obj->flags & UNINTERESTING))
 120                 die("object ranges do not make sense when not walking revisions");
 121         add_object_array(obj, name, &revs->pending);
 122         if (revs->reflog_info && obj->type == OBJ_COMMIT)
 123                 add_reflog_for_walk(revs->reflog_info,
 124                                 (struct commit *)obj, name);
 125 }
 126
 127 static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
 128 {
 129         struct object *object;
 130
 131         object = parse_object(sha1);
 132         if (!object)
 133                 die("bad object %s", name);
 134         object->flags |= flags;
 135         return object;
 136 }
 137
 138 static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
 139 {
 140         unsigned long flags = object->flags;
 141
 142         /*
 143          * Tag object? Look what it points to..
 144          */
 145         while (object->type == OBJ_TAG) {
 146                 struct tag *tag = (struct tag *) object;
 147                 if (revs->tag_objects && !(flags & UNINTERESTING))
 148                         add_pending_object(revs, object, tag->tag);
 149                 object = parse_object(tag->tagged->sha1);
 150                 if (!object)
 151                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
 152         }
 153
 154         /*
 155          * Commit object? Just return it, we'll do all the complex
 156          * reachability crud.
 157          */
 158         if (object->type == OBJ_COMMIT) {
 159                 struct commit *commit = (struct commit *)object;
 160                 if (parse_commit(commit) < 0)
 161                         die("unable to parse commit %s", name);
 162                 if (flags & UNINTERESTING) {
 163                         commit->object.flags |= UNINTERESTING;
 164                         mark_parents_uninteresting(commit);
 165                         revs->limited = 1;
 166                 }
 167                 return commit;
 168         }
 169
 170         /*
 171          * Tree object? Either mark it uniniteresting, or add it
 172          * to the list of objects to look at later..
 173          */
 174         if (object->type == OBJ_TREE) {
 175                 struct tree *tree = (struct tree *)object;
 176                 if (!revs->tree_objects)
 177                         return NULL;
 178                 if (flags & UNINTERESTING) {
 179                         mark_tree_uninteresting(tree);
 180                         return NULL;
 181                 }
 182                 add_pending_object(revs, object, "");
 183                 return NULL;
 184         }
 185
 186         /*
 187          * Blob object? You know the drill by now..
 188          */
 189         if (object->type == OBJ_BLOB) {
 190                 struct blob *blob = (struct blob *)object;
 191                 if (!revs->blob_objects)
 192                         return NULL;
 193                 if (flags & UNINTERESTING) {
 194                         mark_blob_uninteresting(blob);
 195                         return NULL;
 196                 }
 197                 add_pending_object(revs, object, "");
 198                 return NULL;
 199         }
 200         die("%s is unknown object", name);
 201 }
 202
 203 static int everybody_uninteresting(struct commit_list *orig)
 204 {
 205         struct commit_list *list = orig;
 206         while (list) {
 207                 struct commit *commit = list->item;
 208                 list = list->next;
 209                 if (commit->object.flags & UNINTERESTING)
 210                         continue;
 211                 return 0;
 212         }
 213         return 1;
 214 }
 215
 216 /*
 217  * The goal is to get REV_TREE_NEW as the result only if the
 218  * diff consists of all '+' (and no other changes), and
 219  * REV_TREE_DIFFERENT otherwise (of course if the trees are
 220  * the same we want REV_TREE_SAME).  That means that once we
 221  * get to REV_TREE_DIFFERENT, we do not have to look any further.
 222  */
 223 static int tree_difference = REV_TREE_SAME;
 224
 225 static void file_add_remove(struct diff_options *options,
 226                     int addremove, unsigned mode,
 227                     const unsigned char *sha1,
 228                     const char *base, const char *path)
 229 {
 230         int diff = REV_TREE_DIFFERENT;
 231
 232         /*
 233          * Is it an add of a new file? It means that the old tree
 234          * didn't have it at all, so we will turn "REV_TREE_SAME" ->
 235          * "REV_TREE_NEW", but leave any "REV_TREE_DIFFERENT" alone
 236          * (and if it already was "REV_TREE_NEW", we'll keep it
 237          * "REV_TREE_NEW" of course).
 238          */
 239         if (addremove == '+') {
 240                 diff = tree_difference;
 241                 if (diff != REV_TREE_SAME)
 242                         return;
 243                 diff = REV_TREE_NEW;
 244         }
 245         tree_difference = diff;
 246         if (tree_difference == REV_TREE_DIFFERENT)
 247                 options->has_changes = 1;
 248 }
 249
 250 static void file_change(struct diff_options *options,
 251                  unsigned old_mode, unsigned new_mode,
 252                  const unsigned char *old_sha1,
 253                  const unsigned char *new_sha1,
 254                  const char *base, const char *path)
 255 {
 256         tree_difference = REV_TREE_DIFFERENT;
 257         options->has_changes = 1;
 258 }
 259
 260 int rev_compare_tree(struct rev_info *revs, struct tree *t1, struct tree *t2)
 261 {
 262         if (!t1)
 263                 return REV_TREE_NEW;
 264         if (!t2)
 265                 return REV_TREE_DIFFERENT;
 266         tree_difference = REV_TREE_SAME;
 267         revs->pruning.has_changes = 0;
 268         if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "",
 269                            &revs->pruning) < 0)
 270                 return REV_TREE_DIFFERENT;
 271         return tree_difference;
 272 }
 273
 274 int rev_same_tree_as_empty(struct rev_info *revs, struct tree *t1)
 275 {
 276         int retval;
 277         void *tree;
 278         unsigned long size;
 279         struct tree_desc empty, real;
 280
 281         if (!t1)
 282                 return 0;
 283
 284         tree = read_object_with_reference(t1->object.sha1, tree_type, &size, NULL);
 285         if (!tree)
 286                 return 0;
 287         init_tree_desc(&real, tree, size);
 288         init_tree_desc(&empty, "", 0);
 289
 290         tree_difference = REV_TREE_SAME;
 291         revs->pruning.has_changes = 0;
 292         retval = diff_tree(&empty, &real, "", &revs->pruning);
 293         free(tree);
 294
 295         return retval >= 0 && (tree_difference == REV_TREE_SAME);
 296 }
 297
 298 static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
 299 {
 300         struct commit_list **pp, *parent;
 301         int tree_changed = 0, tree_same = 0;
 302
 303         if (!commit->tree)
 304                 return;
 305
 306         if (!commit->parents) {
 307                 if (!rev_same_tree_as_empty(revs, commit->tree))
 308                         commit->object.flags |= TREECHANGE;
 309                 return;
 310         }
 311
 312         pp = &commit->parents;
 313         while ((parent = *pp) != NULL) {
 314                 struct commit *p = parent->item;
 315
 316                 parse_commit(p);
 317                 switch (rev_compare_tree(revs, p->tree, commit->tree)) {
 318                 case REV_TREE_SAME:
 319                         tree_same = 1;
 320                         if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
 321                                 /* Even if a merge with an uninteresting
 322                                  * side branch brought the entire change
 323                                  * we are interested in, we do not want
 324                                  * to lose the other branches of this
 325                                  * merge, so we just keep going.
 326                                  */
 327                                 pp = &parent->next;
 328                                 continue;
 329                         }
 330                         parent->next = NULL;
 331                         commit->parents = parent;
 332                         return;
 333
 334                 case REV_TREE_NEW:
 335                         if (revs->remove_empty_trees &&
 336                             rev_same_tree_as_empty(revs, p->tree)) {
 337                                 /* We are adding all the specified
 338                                  * paths from this parent, so the
 339                                  * history beyond this parent is not
 340                                  * interesting.  Remove its parents
 341                                  * (they are grandparents for us).
 342                                  * IOW, we pretend this parent is a
 343                                  * "root" commit.
 344                                  */
 345                                 parse_commit(p);
 346                                 p->parents = NULL;
 347                         }
 348                 /* fallthrough */
 349                 case REV_TREE_DIFFERENT:
 350                         tree_changed = 1;
 351                         pp = &parent->next;
 352                         continue;
 353                 }
 354                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 355         }
 356         if (tree_changed && !tree_same)
 357                 commit->object.flags |= TREECHANGE;
 358 }
 359
 360 static void add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 361 {
 362         struct commit_list *parent = commit->parents;
 363         unsigned left_flag;
 364         int add, rest;
 365
 366         if (commit->object.flags & ADDED)
 367                 return;
 368         commit->object.flags |= ADDED;
 369
 370         /*
 371          * If the commit is uninteresting, don't try to
 372          * prune parents - we want the maximal uninteresting
 373          * set.
 374          *
 375          * Normally we haven't parsed the parent
 376          * yet, so we won't have a parent of a parent
 377          * here. However, it may turn out that we've
 378          * reached this commit some other way (where it
 379          * wasn't uninteresting), in which case we need
 380          * to mark its parents recursively too..
 381          */
 382         if (commit->object.flags & UNINTERESTING) {
 383                 while (parent) {
 384                         struct commit *p = parent->item;
 385                         parent = parent->next;
 386                         parse_commit(p);
 387                         p->object.flags |= UNINTERESTING;
 388                         if (p->parents)
 389                                 mark_parents_uninteresting(p);
 390                         if (p->object.flags & SEEN)
 391                                 continue;
 392                         p->object.flags |= SEEN;
 393                         insert_by_date(p, list);
 394                 }
 395                 return;
 396         }
 397
 398         /*
 399          * Ok, the commit wasn't uninteresting. Try to
 400          * simplify the commit history and find the parent
 401          * that has no differences in the path set if one exists.
 402          */
 403         if (revs->prune_fn)
 404                 revs->prune_fn(revs, commit);
 405
 406         if (revs->no_walk)
 407                 return;
 408
 409         left_flag = (commit->object.flags & SYMMETRIC_LEFT);
 410
 411         rest = !revs->first_parent_only;
 412         for (parent = commit->parents, add = 1; parent; add = rest) {
 413                 struct commit *p = parent->item;
 414
 415                 parent = parent->next;
 416                 parse_commit(p);
 417                 p->object.flags |= left_flag;
 418                 if (p->object.flags & SEEN)
 419                         continue;
 420                 p->object.flags |= SEEN;
 421                 if (add)
 422                         insert_by_date(p, list);
 423         }
 424 }
 425
 426 static void cherry_pick_list(struct commit_list *list)
 427 {
 428         struct commit_list *p;
 429         int left_count = 0, right_count = 0;
 430         int left_first;
 431         struct patch_ids ids;
 432
 433         /* First count the commits on the left and on the right */
 434         for (p = list; p; p = p->next) {
 435                 struct commit *commit = p->item;
 436                 unsigned flags = commit->object.flags;
 437                 if (flags & BOUNDARY)
 438                         ;
 439                 else if (flags & SYMMETRIC_LEFT)
 440                         left_count++;
 441                 else
 442                         right_count++;
 443         }
 444
 445         left_first = left_count < right_count;
 446         init_patch_ids(&ids);
 447
 448         /* Compute patch-ids for one side */
 449         for (p = list; p; p = p->next) {
 450                 struct commit *commit = p->item;
 451                 unsigned flags = commit->object.flags;
 452
 453                 if (flags & BOUNDARY)
 454                         continue;
 455                 /*
 456                  * If we have fewer left, left_first is set and we omit
 457                  * commits on the right branch in this loop.  If we have
 458                  * fewer right, we skip the left ones.
 459                  */
 460                 if (left_first != !!(flags & SYMMETRIC_LEFT))
 461                         continue;
 462                 commit->util = add_commit_patch_id(commit, &ids);
 463         }
 464
 465         /* Check the other side */
 466         for (p = list; p; p = p->next) {
 467                 struct commit *commit = p->item;
 468                 struct patch_id *id;
 469                 unsigned flags = commit->object.flags;
 470
 471                 if (flags & BOUNDARY)
 472                         continue;
 473                 /*
 474                  * If we have fewer left, left_first is set and we omit
 475                  * commits on the left branch in this loop.
 476                  */
 477                 if (left_first == !!(flags & SYMMETRIC_LEFT))
 478                         continue;
 479
 480                 /*
 481                  * Have we seen the same patch id?
 482                  */
 483                 id = has_commit_patch_id(commit, &ids);
 484                 if (!id)
 485                         continue;
 486                 id->seen = 1;
 487                 commit->object.flags |= SHOWN;
 488         }
 489
 490         /* Now check the original side for seen ones */
 491         for (p = list; p; p = p->next) {
 492                 struct commit *commit = p->item;
 493                 struct patch_id *ent;
 494
 495                 ent = commit->util;
 496                 if (!ent)
 497                         continue;
 498                 if (ent->seen)
 499                         commit->object.flags |= SHOWN;
 500                 commit->util = NULL;
 501         }
 502
 503         free_patch_ids(&ids);
 504 }
 505
 506 static void limit_list(struct rev_info *revs)
 507 {
 508         struct commit_list *list = revs->commits;
 509         struct commit_list *newlist = NULL;
 510         struct commit_list **p = &newlist;
 511
 512         while (list) {
 513                 struct commit_list *entry = list;
 514                 struct commit *commit = list->item;
 515                 struct object *obj = &commit->object;
 516
 517                 list = list->next;
 518                 free(entry);
 519
 520                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 521                         obj->flags |= UNINTERESTING;
 522                 add_parents_to_list(revs, commit, &list);
 523                 if (obj->flags & UNINTERESTING) {
 524                         mark_parents_uninteresting(commit);
 525                         if (everybody_uninteresting(list))
 526                                 break;
 527                         continue;
 528                 }
 529                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 530                         continue;
 531                 p = &commit_list_insert(commit, p)->next;
 532         }
 533         if (revs->cherry_pick)
 534                 cherry_pick_list(newlist);
 535
 536         revs->commits = newlist;
 537 }
 538
 539 struct all_refs_cb {
 540         int all_flags;
 541         int warned_bad_reflog;
 542         struct rev_info *all_revs;
 543         const char *name_for_errormsg;
 544 };
 545
 546 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 547 {
 548         struct all_refs_cb *cb = cb_data;
 549         struct object *object = get_reference(cb->all_revs, path, sha1,
 550                                               cb->all_flags);
 551         add_pending_object(cb->all_revs, object, path);
 552         return 0;
 553 }
 554
 555 static void handle_all(struct rev_info *revs, unsigned flags)
 556 {
 557         struct all_refs_cb cb;
 558         cb.all_revs = revs;
 559         cb.all_flags = flags;
 560         for_each_ref(handle_one_ref, &cb);
 561 }
 562
 563 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 564 {
 565         struct all_refs_cb *cb = cb_data;
 566         if (!is_null_sha1(sha1)) {
 567                 struct object *o = parse_object(sha1);
 568                 if (o) {
 569                         o->flags |= cb->all_flags;
 570                         add_pending_object(cb->all_revs, o, "");
 571                 }
 572                 else if (!cb->warned_bad_reflog) {
 573                         warning("reflog of '%s' references pruned commits",
 574                                 cb->name_for_errormsg);
 575                         cb->warned_bad_reflog = 1;
 576                 }
 577         }
 578 }
 579
 580 static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 581                 const char *email, unsigned long timestamp, int tz,
 582                 const char *message, void *cb_data)
 583 {
 584         handle_one_reflog_commit(osha1, cb_data);
 585         handle_one_reflog_commit(nsha1, cb_data);
 586         return 0;
 587 }
 588
 589 static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 590 {
 591         struct all_refs_cb *cb = cb_data;
 592         cb->warned_bad_reflog = 0;
 593         cb->name_for_errormsg = path;
 594         for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
 595         return 0;
 596 }
 597
 598 static void handle_reflog(struct rev_info *revs, unsigned flags)
 599 {
 600         struct all_refs_cb cb;
 601         cb.all_revs = revs;
 602         cb.all_flags = flags;
 603         for_each_reflog(handle_one_reflog, &cb);
 604 }
 605
 606 static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 607 {
 608         unsigned char sha1[20];
 609         struct object *it;
 610         struct commit *commit;
 611         struct commit_list *parents;
 612
 613         if (*arg == '^') {
 614                 flags ^= UNINTERESTING;
 615                 arg++;
 616         }
 617         if (get_sha1(arg, sha1))
 618                 return 0;
 619         while (1) {
 620                 it = get_reference(revs, arg, sha1, 0);
 621                 if (it->type != OBJ_TAG)
 622                         break;
 623                 hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
 624         }
 625         if (it->type != OBJ_COMMIT)
 626                 return 0;
 627         commit = (struct commit *)it;
 628         for (parents = commit->parents; parents; parents = parents->next) {
 629                 it = &parents->item->object;
 630                 it->flags |= flags;
 631                 add_pending_object(revs, it, arg);
 632         }
 633         return 1;
 634 }
 635
 636 void init_revisions(struct rev_info *revs, const char *prefix)
 637 {
 638         memset(revs, 0, sizeof(*revs));
 639
 640         revs->abbrev = DEFAULT_ABBREV;
 641         revs->ignore_merges = 1;
 642         revs->simplify_history = 1;
 643         revs->pruning.recursive = 1;
 644         revs->pruning.quiet = 1;
 645         revs->pruning.add_remove = file_add_remove;
 646         revs->pruning.change = file_change;
 647         revs->lifo = 1;
 648         revs->dense = 1;
 649         revs->prefix = prefix;
 650         revs->max_age = -1;
 651         revs->min_age = -1;
 652         revs->skip_count = -1;
 653         revs->max_count = -1;
 654         revs->subject_prefix = "PATCH";
 655
 656         revs->prune_fn = NULL;
 657         revs->prune_data = NULL;
 658
 659         revs->topo_setter = topo_sort_default_setter;
 660         revs->topo_getter = topo_sort_default_getter;
 661
 662         revs->commit_format = CMIT_FMT_DEFAULT;
 663
 664         diff_setup(&revs->diffopt);
 665 }
 666
 667 static void add_pending_commit_list(struct rev_info *revs,
 668                                     struct commit_list *commit_list,
 669                                     unsigned int flags)
 670 {
 671         while (commit_list) {
 672                 struct object *object = &commit_list->item->object;
 673                 object->flags |= flags;
 674                 add_pending_object(revs, object, sha1_to_hex(object->sha1));
 675                 commit_list = commit_list->next;
 676         }
 677 }
 678
 679 static void prepare_show_merge(struct rev_info *revs)
 680 {
 681         struct commit_list *bases;
 682         struct commit *head, *other;
 683         unsigned char sha1[20];
 684         const char **prune = NULL;
 685         int i, prune_num = 1; /* counting terminating NULL */
 686
 687         if (get_sha1("HEAD", sha1) || !(head = lookup_commit(sha1)))
 688                 die("--merge without HEAD?");
 689         if (get_sha1("MERGE_HEAD", sha1) || !(other = lookup_commit(sha1)))
 690                 die("--merge without MERGE_HEAD?");
 691         add_pending_object(revs, &head->object, "HEAD");
 692         add_pending_object(revs, &other->object, "MERGE_HEAD");
 693         bases = get_merge_bases(head, other, 1);
 694         while (bases) {
 695                 struct commit *it = bases->item;
 696                 struct commit_list *n = bases->next;
 697                 free(bases);
 698                 bases = n;
 699                 it->object.flags |= UNINTERESTING;
 700                 add_pending_object(revs, &it->object, "(merge-base)");
 701         }
 702
 703         if (!active_nr)
 704                 read_cache();
 705         for (i = 0; i < active_nr; i++) {
 706                 struct cache_entry *ce = active_cache[i];
 707                 if (!ce_stage(ce))
 708                         continue;
 709                 if (ce_path_match(ce, revs->prune_data)) {
 710                         prune_num++;
 711                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
 712                         prune[prune_num-2] = ce->name;
 713                         prune[prune_num-1] = NULL;
 714                 }
 715                 while ((i+1 < active_nr) &&
 716                        ce_same_name(ce, active_cache[i+1]))
 717                         i++;
 718         }
 719         revs->prune_data = prune;
 720 }
 721
 722 int handle_revision_arg(const char *arg, struct rev_info *revs,
 723                         int flags,
 724                         int cant_be_filename)
 725 {
 726         char *dotdot;
 727         struct object *object;
 728         unsigned char sha1[20];
 729         int local_flags;
 730
 731         dotdot = strstr(arg, "..");
 732         if (dotdot) {
 733                 unsigned char from_sha1[20];
 734                 const char *next = dotdot + 2;
 735                 const char *this = arg;
 736                 int symmetric = *next == '.';
 737                 unsigned int flags_exclude = flags ^ UNINTERESTING;
 738
 739                 *dotdot = 0;
 740                 next += symmetric;
 741
 742                 if (!*next)
 743                         next = "HEAD";
 744                 if (dotdot == arg)
 745                         this = "HEAD";
 746                 if (!get_sha1(this, from_sha1) &&
 747                     !get_sha1(next, sha1)) {
 748                         struct commit *a, *b;
 749                         struct commit_list *exclude;
 750
 751                         a = lookup_commit_reference(from_sha1);
 752                         b = lookup_commit_reference(sha1);
 753                         if (!a || !b) {
 754                                 die(symmetric ?
 755                                     "Invalid symmetric difference expression %s...%s" :
 756                                     "Invalid revision range %s..%s",
 757                                     arg, next);
 758                         }
 759
 760                         if (!cant_be_filename) {
 761                                 *dotdot = '.';
 762                                 verify_non_filename(revs->prefix, arg);
 763                         }
 764
 765                         if (symmetric) {
 766                                 exclude = get_merge_bases(a, b, 1);
 767                                 add_pending_commit_list(revs, exclude,
 768                                                         flags_exclude);
 769                                 free_commit_list(exclude);
 770                                 a->object.flags |= flags | SYMMETRIC_LEFT;
 771                         } else
 772                                 a->object.flags |= flags_exclude;
 773                         b->object.flags |= flags;
 774                         add_pending_object(revs, &a->object, this);
 775                         add_pending_object(revs, &b->object, next);
 776                         return 0;
 777                 }
 778                 *dotdot = '.';
 779         }
 780         dotdot = strstr(arg, "^@");
 781         if (dotdot && !dotdot[2]) {
 782                 *dotdot = 0;
 783                 if (add_parents_only(revs, arg, flags))
 784                         return 0;
 785                 *dotdot = '^';
 786         }
 787         dotdot = strstr(arg, "^!");
 788         if (dotdot && !dotdot[2]) {
 789                 *dotdot = 0;
 790                 if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
 791                         *dotdot = '^';
 792         }
 793
 794         local_flags = 0;
 795         if (*arg == '^') {
 796                 local_flags = UNINTERESTING;
 797                 arg++;
 798         }
 799         if (get_sha1(arg, sha1))
 800                 return -1;
 801         if (!cant_be_filename)
 802                 verify_non_filename(revs->prefix, arg);
 803         object = get_reference(revs, arg, sha1, flags ^ local_flags);
 804         add_pending_object(revs, object, arg);
 805         return 0;
 806 }
 807
 808 static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
 809 {
 810         if (!revs->grep_filter) {
 811                 struct grep_opt *opt = xcalloc(1, sizeof(*opt));
 812                 opt->status_only = 1;
 813                 opt->pattern_tail = &(opt->pattern_list);
 814                 opt->regflags = REG_NEWLINE;
 815                 revs->grep_filter = opt;
 816         }
 817         append_grep_pattern(revs->grep_filter, ptn,
 818                             "command line", 0, what);
 819 }
 820
 821 static void add_header_grep(struct rev_info *revs, const char *field, const char *pattern)
 822 {
 823         char *pat;
 824         const char *prefix;
 825         int patlen, fldlen;
 826
 827         fldlen = strlen(field);
 828         patlen = strlen(pattern);
 829         pat = xmalloc(patlen + fldlen + 10);
 830         prefix = ".*";
 831         if (*pattern == '^') {
 832                 prefix = "";
 833                 pattern++;
 834         }
 835         sprintf(pat, "^%s %s%s", field, prefix, pattern);
 836         add_grep(revs, pat, GREP_PATTERN_HEAD);
 837 }
 838
 839 static void add_message_grep(struct rev_info *revs, const char *pattern)
 840 {
 841         add_grep(revs, pattern, GREP_PATTERN_BODY);
 842 }
 843
 844 static void add_ignore_packed(struct rev_info *revs, const char *name)
 845 {
 846         int num = ++revs->num_ignore_packed;
 847
 848         revs->ignore_packed = xrealloc(revs->ignore_packed,
 849                                        sizeof(const char **) * (num + 1));
 850         revs->ignore_packed[num-1] = name;
 851         revs->ignore_packed[num] = NULL;
 852 }
 853
 854 /*
 855  * Parse revision information, filling in the "rev_info" structure,
 856  * and removing the used arguments from the argument list.
 857  *
 858  * Returns the number of arguments left that weren't recognized
 859  * (which are also moved to the head of the argument list)
 860  */
 861 int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
 862 {
 863         int i, flags, seen_dashdash, show_merge;
 864         const char **unrecognized = argv + 1;
 865         int left = 1;
 866         int all_match = 0;
 867
 868         /* First, search for "--" */
 869         seen_dashdash = 0;
 870         for (i = 1; i < argc; i++) {
 871                 const char *arg = argv[i];
 872                 if (strcmp(arg, "--"))
 873                         continue;
 874                 argv[i] = NULL;
 875                 argc = i;
 876                 revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
 877                 seen_dashdash = 1;
 878                 break;
 879         }
 880
 881         flags = show_merge = 0;
 882         for (i = 1; i < argc; i++) {
 883                 const char *arg = argv[i];
 884                 if (*arg == '-') {
 885                         int opts;
 886                         if (!prefixcmp(arg, "--max-count=")) {
 887                                 revs->max_count = atoi(arg + 12);
 888                                 continue;
 889                         }
 890                         if (!prefixcmp(arg, "--skip=")) {
 891                                 revs->skip_count = atoi(arg + 7);
 892                                 continue;
 893                         }
 894                         /* accept -<digit>, like traditional "head" */
 895                         if ((*arg == '-') && isdigit(arg[1])) {
 896                                 revs->max_count = atoi(arg + 1);
 897                                 continue;
 898                         }
 899                         if (!strcmp(arg, "-n")) {
 900                                 if (argc <= i + 1)
 901                                         die("-n requires an argument");
 902                                 revs->max_count = atoi(argv[++i]);
 903                                 continue;
 904                         }
 905                         if (!prefixcmp(arg, "-n")) {
 906                                 revs->max_count = atoi(arg + 2);
 907                                 continue;
 908                         }
 909                         if (!prefixcmp(arg, "--max-age=")) {
 910                                 revs->max_age = atoi(arg + 10);
 911                                 continue;
 912                         }
 913                         if (!prefixcmp(arg, "--since=")) {
 914                                 revs->max_age = approxidate(arg + 8);
 915                                 continue;
 916                         }
 917                         if (!prefixcmp(arg, "--after=")) {
 918                                 revs->max_age = approxidate(arg + 8);
 919                                 continue;
 920                         }
 921                         if (!prefixcmp(arg, "--min-age=")) {
 922                                 revs->min_age = atoi(arg + 10);
 923                                 continue;
 924                         }
 925                         if (!prefixcmp(arg, "--before=")) {
 926                                 revs->min_age = approxidate(arg + 9);
 927                                 continue;
 928                         }
 929                         if (!prefixcmp(arg, "--until=")) {
 930                                 revs->min_age = approxidate(arg + 8);
 931                                 continue;
 932                         }
 933                         if (!strcmp(arg, "--all")) {
 934                                 handle_all(revs, flags);
 935                                 continue;
 936                         }
 937                         if (!strcmp(arg, "--first-parent")) {
 938                                 revs->first_parent_only = 1;
 939                                 continue;
 940                         }
 941                         if (!strcmp(arg, "--reflog")) {
 942                                 handle_reflog(revs, flags);
 943                                 continue;
 944                         }
 945                         if (!strcmp(arg, "-g") ||
 946                                         !strcmp(arg, "--walk-reflogs")) {
 947                                 init_reflog_walk(&revs->reflog_info);
 948                                 continue;
 949                         }
 950                         if (!strcmp(arg, "--not")) {
 951                                 flags ^= UNINTERESTING;
 952                                 continue;
 953                         }
 954                         if (!strcmp(arg, "--default")) {
 955                                 if (++i >= argc)
 956                                         die("bad --default argument");
 957                                 def = argv[i];
 958                                 continue;
 959                         }
 960                         if (!strcmp(arg, "--merge")) {
 961                                 show_merge = 1;
 962                                 continue;
 963                         }
 964                         if (!strcmp(arg, "--topo-order")) {
 965                                 revs->topo_order = 1;
 966                                 continue;
 967                         }
 968                         if (!strcmp(arg, "--date-order")) {
 969                                 revs->lifo = 0;
 970                                 revs->topo_order = 1;
 971                                 continue;
 972                         }
 973                         if (!strcmp(arg, "--parents")) {
 974                                 revs->parents = 1;
 975                                 continue;
 976                         }
 977                         if (!strcmp(arg, "--dense")) {
 978                                 revs->dense = 1;
 979                                 continue;
 980                         }
 981                         if (!strcmp(arg, "--sparse")) {
 982                                 revs->dense = 0;
 983                                 continue;
 984                         }
 985                         if (!strcmp(arg, "--remove-empty")) {
 986                                 revs->remove_empty_trees = 1;
 987                                 continue;
 988                         }
 989                         if (!strcmp(arg, "--no-merges")) {
 990                                 revs->no_merges = 1;
 991                                 continue;
 992                         }
 993                         if (!strcmp(arg, "--boundary")) {
 994                                 revs->boundary = 1;
 995                                 continue;
 996                         }
 997                         if (!strcmp(arg, "--left-right")) {
 998                                 revs->left_right = 1;
 999                                 continue;
1000                         }
1001                         if (!strcmp(arg, "--cherry-pick")) {
1002                                 revs->cherry_pick = 1;
1003                                 continue;
1004                         }
1005                         if (!strcmp(arg, "--objects")) {
1006                                 revs->tag_objects = 1;
1007                                 revs->tree_objects = 1;
1008                                 revs->blob_objects = 1;
1009                                 continue;
1010                         }
1011                         if (!strcmp(arg, "--objects-edge")) {
1012                                 revs->tag_objects = 1;
1013                                 revs->tree_objects = 1;
1014                                 revs->blob_objects = 1;
1015                                 revs->edge_hint = 1;
1016                                 continue;
1017                         }
1018                         if (!strcmp(arg, "--unpacked")) {
1019                                 revs->unpacked = 1;
1020                                 free(revs->ignore_packed);
1021                                 revs->ignore_packed = NULL;
1022                                 revs->num_ignore_packed = 0;
1023                                 continue;
1024                         }
1025                         if (!prefixcmp(arg, "--unpacked=")) {
1026                                 revs->unpacked = 1;
1027                                 add_ignore_packed(revs, arg+11);
1028                                 continue;
1029                         }
1030                         if (!strcmp(arg, "-r")) {
1031                                 revs->diff = 1;
1032                                 revs->diffopt.recursive = 1;
1033                                 continue;
1034                         }
1035                         if (!strcmp(arg, "-t")) {
1036                                 revs->diff = 1;
1037                                 revs->diffopt.recursive = 1;
1038                                 revs->diffopt.tree_in_recursive = 1;
1039                                 continue;
1040                         }
1041                         if (!strcmp(arg, "-m")) {
1042                                 revs->ignore_merges = 0;
1043                                 continue;
1044                         }
1045                         if (!strcmp(arg, "-c")) {
1046                                 revs->diff = 1;
1047                                 revs->dense_combined_merges = 0;
1048                                 revs->combine_merges = 1;
1049                                 continue;
1050                         }
1051                         if (!strcmp(arg, "--cc")) {
1052                                 revs->diff = 1;
1053                                 revs->dense_combined_merges = 1;
1054                                 revs->combine_merges = 1;
1055                                 continue;
1056                         }
1057                         if (!strcmp(arg, "-v")) {
1058                                 revs->verbose_header = 1;
1059                                 continue;
1060                         }
1061                         if (!prefixcmp(arg, "--pretty")) {
1062                                 revs->verbose_header = 1;
1063                                 revs->commit_format = get_commit_format(arg+8);
1064                                 continue;
1065                         }
1066                         if (!strcmp(arg, "--root")) {
1067                                 revs->show_root_diff = 1;
1068                                 continue;
1069                         }
1070                         if (!strcmp(arg, "--no-commit-id")) {
1071                                 revs->no_commit_id = 1;
1072                                 continue;
1073                         }
1074                         if (!strcmp(arg, "--always")) {
1075                                 revs->always_show_header = 1;
1076                                 continue;
1077                         }
1078                         if (!strcmp(arg, "--no-abbrev")) {
1079                                 revs->abbrev = 0;
1080                                 continue;
1081                         }
1082                         if (!strcmp(arg, "--abbrev")) {
1083                                 revs->abbrev = DEFAULT_ABBREV;
1084                                 continue;
1085                         }
1086                         if (!prefixcmp(arg, "--abbrev=")) {
1087                                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1088                                 if (revs->abbrev < MINIMUM_ABBREV)
1089                                         revs->abbrev = MINIMUM_ABBREV;
1090                                 else if (revs->abbrev > 40)
1091                                         revs->abbrev = 40;
1092                                 continue;
1093                         }
1094                         if (!strcmp(arg, "--abbrev-commit")) {
1095                                 revs->abbrev_commit = 1;
1096                                 continue;
1097                         }
1098                         if (!strcmp(arg, "--full-diff")) {
1099                                 revs->diff = 1;
1100                                 revs->full_diff = 1;
1101                                 continue;
1102                         }
1103                         if (!strcmp(arg, "--full-history")) {
1104                                 revs->simplify_history = 0;
1105                                 continue;
1106                         }
1107                         if (!strcmp(arg, "--relative-date")) {
1108                                 revs->relative_date = 1;
1109                                 continue;
1110                         }
1111
1112                         /*
1113                          * Grepping the commit log
1114                          */
1115                         if (!prefixcmp(arg, "--author=")) {
1116                                 add_header_grep(revs, "author", arg+9);
1117                                 continue;
1118                         }
1119                         if (!prefixcmp(arg, "--committer=")) {
1120                                 add_header_grep(revs, "committer", arg+12);
1121                                 continue;
1122                         }
1123                         if (!prefixcmp(arg, "--grep=")) {
1124                                 add_message_grep(revs, arg+7);
1125                                 continue;
1126                         }
1127                         if (!strcmp(arg, "--all-match")) {
1128                                 all_match = 1;
1129                                 continue;
1130                         }
1131                         if (!prefixcmp(arg, "--encoding=")) {
1132                                 arg += 11;
1133                                 if (strcmp(arg, "none"))
1134                                         git_log_output_encoding = xstrdup(arg);
1135                                 else
1136                                         git_log_output_encoding = "";
1137                                 continue;
1138                         }
1139                         if (!strcmp(arg, "--reverse")) {
1140                                 revs->reverse ^= 1;
1141                                 continue;
1142                         }
1143
1144                         opts = diff_opt_parse(&revs->diffopt, argv+i, argc-i);
1145                         if (opts > 0) {
1146                                 revs->diff = 1;
1147                                 i += opts - 1;
1148                                 continue;
1149                         }
1150                         *unrecognized++ = arg;
1151                         left++;
1152                         continue;
1153                 }
1154
1155                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1156                         int j;
1157                         if (seen_dashdash || *arg == '^')
1158                                 die("bad revision '%s'", arg);
1159
1160                         /* If we didn't have a "--":
1161                          * (1) all filenames must exist;
1162                          * (2) all rev-args must not be interpretable
1163                          *     as a valid filename.
1164                          * but the latter we have checked in the main loop.
1165                          */
1166                         for (j = i; j < argc; j++)
1167                                 verify_filename(revs->prefix, argv[j]);
1168
1169                         revs->prune_data = get_pathspec(revs->prefix,
1170                                                         argv + i);
1171                         break;
1172                 }
1173         }
1174
1175         if (show_merge)
1176                 prepare_show_merge(revs);
1177         if (def && !revs->pending.nr) {
1178                 unsigned char sha1[20];
1179                 struct object *object;
1180                 if (get_sha1(def, sha1))
1181                         die("bad default revision '%s'", def);
1182                 object = get_reference(revs, def, sha1, 0);
1183                 add_pending_object(revs, object, def);
1184         }
1185
1186         if (revs->topo_order)
1187                 revs->limited = 1;
1188
1189         if (revs->prune_data) {
1190                 diff_tree_setup_paths(revs->prune_data, &revs->pruning);
1191                 revs->prune_fn = try_to_simplify_commit;
1192                 if (!revs->full_diff)
1193                         diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
1194         }
1195         if (revs->combine_merges) {
1196                 revs->ignore_merges = 0;
1197                 if (revs->dense_combined_merges && !revs->diffopt.output_format)
1198                         revs->diffopt.output_format = DIFF_FORMAT_PATCH;
1199         }
1200         revs->diffopt.abbrev = revs->abbrev;
1201         if (diff_setup_done(&revs->diffopt) < 0)
1202                 die("diff_setup_done failed");
1203
1204         if (revs->grep_filter) {
1205                 revs->grep_filter->all_match = all_match;
1206                 compile_grep_patterns(revs->grep_filter);
1207         }
1208
1209         return left;
1210 }
1211
1212 void prepare_revision_walk(struct rev_info *revs)
1213 {
1214         int nr = revs->pending.nr;
1215         struct object_array_entry *e, *list;
1216
1217         e = list = revs->pending.objects;
1218         revs->pending.nr = 0;
1219         revs->pending.alloc = 0;
1220         revs->pending.objects = NULL;
1221         while (--nr >= 0) {
1222                 struct commit *commit = handle_commit(revs, e->item, e->name);
1223                 if (commit) {
1224                         if (!(commit->object.flags & SEEN)) {
1225                                 commit->object.flags |= SEEN;
1226                                 insert_by_date(commit, &revs->commits);
1227                         }
1228                 }
1229                 e++;
1230         }
1231         free(list);
1232
1233         if (revs->no_walk)
1234                 return;
1235         if (revs->limited)
1236                 limit_list(revs);
1237         if (revs->topo_order)
1238                 sort_in_topological_order_fn(&revs->commits, revs->lifo,
1239                                              revs->topo_setter,
1240                                              revs->topo_getter);
1241 }
1242
1243 static int rewrite_one(struct rev_info *revs, struct commit **pp)
1244 {
1245         for (;;) {
1246                 struct commit *p = *pp;
1247                 if (!revs->limited)
1248                         add_parents_to_list(revs, p, &revs->commits);
1249                 if (p->parents && p->parents->next)
1250                         return 0;
1251                 if (p->object.flags & (TREECHANGE | UNINTERESTING))
1252                         return 0;
1253                 if (!p->parents)
1254                         return -1;
1255                 *pp = p->parents->item;
1256         }
1257 }
1258
1259 static void rewrite_parents(struct rev_info *revs, struct commit *commit)
1260 {
1261         struct commit_list **pp = &commit->parents;
1262         while (*pp) {
1263                 struct commit_list *parent = *pp;
1264                 if (rewrite_one(revs, &parent->item) < 0) {
1265                         *pp = parent->next;
1266                         continue;
1267                 }
1268                 pp = &parent->next;
1269         }
1270 }
1271
1272 static int commit_match(struct commit *commit, struct rev_info *opt)
1273 {
1274         if (!opt->grep_filter)
1275                 return 1;
1276         return grep_buffer(opt->grep_filter,
1277                            NULL, /* we say nothing, not even filename */
1278                            commit->buffer, strlen(commit->buffer));
1279 }
1280
1281 static struct commit *get_revision_1(struct rev_info *revs)
1282 {
1283         if (!revs->commits)
1284                 return NULL;
1285
1286         do {
1287                 struct commit_list *entry = revs->commits;
1288                 struct commit *commit = entry->item;
1289
1290                 revs->commits = entry->next;
1291                 free(entry);
1292
1293                 if (revs->reflog_info)
1294                         fake_reflog_parent(revs->reflog_info, commit);
1295
1296                 /*
1297                  * If we haven't done the list limiting, we need to look at
1298                  * the parents here. We also need to do the date-based limiting
1299                  * that we'd otherwise have done in limit_list().
1300                  */
1301                 if (!revs->limited) {
1302                         if (revs->max_age != -1 &&
1303                             (commit->date < revs->max_age))
1304                                 continue;
1305                         add_parents_to_list(revs, commit, &revs->commits);
1306                 }
1307                 if (commit->object.flags & SHOWN)
1308                         continue;
1309
1310                 if (revs->unpacked && has_sha1_pack(commit->object.sha1,
1311                                                     revs->ignore_packed))
1312                     continue;
1313
1314                 if (commit->object.flags & UNINTERESTING)
1315                         continue;
1316                 if (revs->min_age != -1 && (commit->date > revs->min_age))
1317                         continue;
1318                 if (revs->no_merges &&
1319                     commit->parents && commit->parents->next)
1320                         continue;
1321                 if (!commit_match(commit, revs))
1322                         continue;
1323                 if (revs->prune_fn && revs->dense) {
1324                         /* Commit without changes? */
1325                         if (!(commit->object.flags & TREECHANGE)) {
1326                                 /* drop merges unless we want parenthood */
1327                                 if (!revs->parents)
1328                                         continue;
1329                                 /* non-merge - always ignore it */
1330                                 if (!commit->parents || !commit->parents->next)
1331                                         continue;
1332                         }
1333                         if (revs->parents)
1334                                 rewrite_parents(revs, commit);
1335                 }
1336                 return commit;
1337         } while (revs->commits);
1338         return NULL;
1339 }
1340
1341 static void gc_boundary(struct object_array *array)
1342 {
1343         unsigned nr = array->nr;
1344         unsigned alloc = array->alloc;
1345         struct object_array_entry *objects = array->objects;
1346
1347         if (alloc <= nr) {
1348                 unsigned i, j;
1349                 for (i = j = 0; i < nr; i++) {
1350                         if (objects[i].item->flags & SHOWN)
1351                                 continue;
1352                         if (i != j)
1353                                 objects[j] = objects[i];
1354                         j++;
1355                 }
1356                 for (i = j; i < nr; i++)
1357                         objects[i].item = NULL;
1358                 array->nr = j;
1359         }
1360 }
1361
1362 struct commit *get_revision(struct rev_info *revs)
1363 {
1364         struct commit *c = NULL;
1365         struct commit_list *l;
1366
1367         if (revs->boundary == 2) {
1368                 unsigned i;
1369                 struct object_array *array = &revs->boundary_commits;
1370                 struct object_array_entry *objects = array->objects;
1371                 for (i = 0; i < array->nr; i++) {
1372                         c = (struct commit *)(objects[i].item);
1373                         if (!c)
1374                                 continue;
1375                         if (!(c->object.flags & CHILD_SHOWN))
1376                                 continue;
1377                         if (!(c->object.flags & SHOWN))
1378                                 break;
1379                 }
1380                 if (array->nr <= i)
1381                         return NULL;
1382
1383                 c->object.flags |= SHOWN | BOUNDARY;
1384                 return c;
1385         }
1386
1387         if (revs->reverse) {
1388                 int limit = -1;
1389
1390                 if (0 <= revs->max_count) {
1391                         limit = revs->max_count;
1392                         if (0 < revs->skip_count)
1393                                 limit += revs->skip_count;
1394                 }
1395                 l = NULL;
1396                 while ((c = get_revision_1(revs))) {
1397                         commit_list_insert(c, &l);
1398                         if ((0 < limit) && !--limit)
1399                                 break;
1400                 }
1401                 revs->commits = l;
1402                 revs->reverse = 0;
1403                 revs->max_count = -1;
1404                 c = NULL;
1405         }
1406
1407         /*
1408          * Now pick up what they want to give us
1409          */
1410         c = get_revision_1(revs);
1411         if (c) {
1412                 while (0 < revs->skip_count) {
1413                         revs->skip_count--;
1414                         c = get_revision_1(revs);
1415                         if (!c)
1416                                 break;
1417                 }
1418         }
1419
1420         /*
1421          * Check the max_count.
1422          */
1423         switch (revs->max_count) {
1424         case -1:
1425                 break;
1426         case 0:
1427                 c = NULL;
1428                 break;
1429         default:
1430                 revs->max_count--;
1431         }
1432
1433         if (c)
1434                 c->object.flags |= SHOWN;
1435
1436         if (!revs->boundary) {
1437                 return c;
1438         }
1439
1440         if (!c) {
1441                 /*
1442                  * get_revision_1() runs out the commits, and
1443                  * we are done computing the boundaries.
1444                  * switch to boundary commits output mode.
1445                  */
1446                 revs->boundary = 2;
1447                 return get_revision(revs);
1448         }
1449
1450         /*
1451          * boundary commits are the commits that are parents of the
1452          * ones we got from get_revision_1() but they themselves are
1453          * not returned from get_revision_1().  Before returning
1454          * 'c', we need to mark its parents that they could be boundaries.
1455          */
1456
1457         for (l = c->parents; l; l = l->next) {
1458                 struct object *p;
1459                 p = &(l->item->object);
1460                 if (p->flags & (CHILD_SHOWN | SHOWN))
1461                         continue;
1462                 p->flags |= CHILD_SHOWN;
1463                 gc_boundary(&revs->boundary_commits);
1464                 add_object_array(p, NULL, &revs->boundary_commits);
1465         }
1466
1467         return c;
1468 }