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         add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
 120 }
 121
 122 void add_pending_object_with_mode(struct rev_info *revs, struct object *obj, const char *name, unsigned mode)
 123 {
 124         if (revs->no_walk && (obj->flags & UNINTERESTING))
 125                 die("object ranges do not make sense when not walking revisions");
 126         add_object_array_with_mode(obj, name, &revs->pending, mode);
 127         if (revs->reflog_info && obj->type == OBJ_COMMIT)
 128                 add_reflog_for_walk(revs->reflog_info,
 129                                 (struct commit *)obj, name);
 130 }
 131
 132 static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
 133 {
 134         struct object *object;
 135
 136         object = parse_object(sha1);
 137         if (!object)
 138                 die("bad object %s", name);
 139         object->flags |= flags;
 140         return object;
 141 }
 142
 143 static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
 144 {
 145         unsigned long flags = object->flags;
 146
 147         /*
 148          * Tag object? Look what it points to..
 149          */
 150         while (object->type == OBJ_TAG) {
 151                 struct tag *tag = (struct tag *) object;
 152                 if (revs->tag_objects && !(flags & UNINTERESTING))
 153                         add_pending_object(revs, object, tag->tag);
 154                 object = parse_object(tag->tagged->sha1);
 155                 if (!object)
 156                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
 157         }
 158
 159         /*
 160          * Commit object? Just return it, we'll do all the complex
 161          * reachability crud.
 162          */
 163         if (object->type == OBJ_COMMIT) {
 164                 struct commit *commit = (struct commit *)object;
 165                 if (parse_commit(commit) < 0)
 166                         die("unable to parse commit %s", name);
 167                 if (flags & UNINTERESTING) {
 168                         commit->object.flags |= UNINTERESTING;
 169                         mark_parents_uninteresting(commit);
 170                         revs->limited = 1;
 171                 }
 172                 return commit;
 173         }
 174
 175         /*
 176          * Tree object? Either mark it uniniteresting, or add it
 177          * to the list of objects to look at later..
 178          */
 179         if (object->type == OBJ_TREE) {
 180                 struct tree *tree = (struct tree *)object;
 181                 if (!revs->tree_objects)
 182                         return NULL;
 183                 if (flags & UNINTERESTING) {
 184                         mark_tree_uninteresting(tree);
 185                         return NULL;
 186                 }
 187                 add_pending_object(revs, object, "");
 188                 return NULL;
 189         }
 190
 191         /*
 192          * Blob object? You know the drill by now..
 193          */
 194         if (object->type == OBJ_BLOB) {
 195                 struct blob *blob = (struct blob *)object;
 196                 if (!revs->blob_objects)
 197                         return NULL;
 198                 if (flags & UNINTERESTING) {
 199                         mark_blob_uninteresting(blob);
 200                         return NULL;
 201                 }
 202                 add_pending_object(revs, object, "");
 203                 return NULL;
 204         }
 205         die("%s is unknown object", name);
 206 }
 207
 208 static int everybody_uninteresting(struct commit_list *orig)
 209 {
 210         struct commit_list *list = orig;
 211         while (list) {
 212                 struct commit *commit = list->item;
 213                 list = list->next;
 214                 if (commit->object.flags & UNINTERESTING)
 215                         continue;
 216                 return 0;
 217         }
 218         return 1;
 219 }
 220
 221 /*
 222  * The goal is to get REV_TREE_NEW as the result only if the
 223  * diff consists of all '+' (and no other changes), and
 224  * REV_TREE_DIFFERENT otherwise (of course if the trees are
 225  * the same we want REV_TREE_SAME).  That means that once we
 226  * get to REV_TREE_DIFFERENT, we do not have to look any further.
 227  */
 228 static int tree_difference = REV_TREE_SAME;
 229
 230 static void file_add_remove(struct diff_options *options,
 231                     int addremove, unsigned mode,
 232                     const unsigned char *sha1,
 233                     const char *base, const char *path)
 234 {
 235         int diff = REV_TREE_DIFFERENT;
 236
 237         /*
 238          * Is it an add of a new file? It means that the old tree
 239          * didn't have it at all, so we will turn "REV_TREE_SAME" ->
 240          * "REV_TREE_NEW", but leave any "REV_TREE_DIFFERENT" alone
 241          * (and if it already was "REV_TREE_NEW", we'll keep it
 242          * "REV_TREE_NEW" of course).
 243          */
 244         if (addremove == '+') {
 245                 diff = tree_difference;
 246                 if (diff != REV_TREE_SAME)
 247                         return;
 248                 diff = REV_TREE_NEW;
 249         }
 250         tree_difference = diff;
 251         if (tree_difference == REV_TREE_DIFFERENT)
 252                 options->has_changes = 1;
 253 }
 254
 255 static void file_change(struct diff_options *options,
 256                  unsigned old_mode, unsigned new_mode,
 257                  const unsigned char *old_sha1,
 258                  const unsigned char *new_sha1,
 259                  const char *base, const char *path)
 260 {
 261         tree_difference = REV_TREE_DIFFERENT;
 262         options->has_changes = 1;
 263 }
 264
 265 int rev_compare_tree(struct rev_info *revs, struct tree *t1, struct tree *t2)
 266 {
 267         if (!t1)
 268                 return REV_TREE_NEW;
 269         if (!t2)
 270                 return REV_TREE_DIFFERENT;
 271         tree_difference = REV_TREE_SAME;
 272         revs->pruning.has_changes = 0;
 273         if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "",
 274                            &revs->pruning) < 0)
 275                 return REV_TREE_DIFFERENT;
 276         return tree_difference;
 277 }
 278
 279 int rev_same_tree_as_empty(struct rev_info *revs, struct tree *t1)
 280 {
 281         int retval;
 282         void *tree;
 283         unsigned long size;
 284         struct tree_desc empty, real;
 285
 286         if (!t1)
 287                 return 0;
 288
 289         tree = read_object_with_reference(t1->object.sha1, tree_type, &size, NULL);
 290         if (!tree)
 291                 return 0;
 292         init_tree_desc(&real, tree, size);
 293         init_tree_desc(&empty, "", 0);
 294
 295         tree_difference = REV_TREE_SAME;
 296         revs->pruning.has_changes = 0;
 297         retval = diff_tree(&empty, &real, "", &revs->pruning);
 298         free(tree);
 299
 300         return retval >= 0 && (tree_difference == REV_TREE_SAME);
 301 }
 302
 303 static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
 304 {
 305         struct commit_list **pp, *parent;
 306         int tree_changed = 0, tree_same = 0;
 307
 308         if (!commit->tree)
 309                 return;
 310
 311         if (!commit->parents) {
 312                 if (!rev_same_tree_as_empty(revs, commit->tree))
 313                         commit->object.flags |= TREECHANGE;
 314                 return;
 315         }
 316
 317         pp = &commit->parents;
 318         while ((parent = *pp) != NULL) {
 319                 struct commit *p = parent->item;
 320
 321                 parse_commit(p);
 322                 switch (rev_compare_tree(revs, p->tree, commit->tree)) {
 323                 case REV_TREE_SAME:
 324                         tree_same = 1;
 325                         if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
 326                                 /* Even if a merge with an uninteresting
 327                                  * side branch brought the entire change
 328                                  * we are interested in, we do not want
 329                                  * to lose the other branches of this
 330                                  * merge, so we just keep going.
 331                                  */
 332                                 pp = &parent->next;
 333                                 continue;
 334                         }
 335                         parent->next = NULL;
 336                         commit->parents = parent;
 337                         return;
 338
 339                 case REV_TREE_NEW:
 340                         if (revs->remove_empty_trees &&
 341                             rev_same_tree_as_empty(revs, p->tree)) {
 342                                 /* We are adding all the specified
 343                                  * paths from this parent, so the
 344                                  * history beyond this parent is not
 345                                  * interesting.  Remove its parents
 346                                  * (they are grandparents for us).
 347                                  * IOW, we pretend this parent is a
 348                                  * "root" commit.
 349                                  */
 350                                 parse_commit(p);
 351                                 p->parents = NULL;
 352                         }
 353                 /* fallthrough */
 354                 case REV_TREE_DIFFERENT:
 355                         tree_changed = 1;
 356                         pp = &parent->next;
 357                         continue;
 358                 }
 359                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 360         }
 361         if (tree_changed && !tree_same)
 362                 commit->object.flags |= TREECHANGE;
 363 }
 364
 365 static void add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 366 {
 367         struct commit_list *parent = commit->parents;
 368         unsigned left_flag;
 369         int add, rest;
 370
 371         if (commit->object.flags & ADDED)
 372                 return;
 373         commit->object.flags |= ADDED;
 374
 375         /*
 376          * If the commit is uninteresting, don't try to
 377          * prune parents - we want the maximal uninteresting
 378          * set.
 379          *
 380          * Normally we haven't parsed the parent
 381          * yet, so we won't have a parent of a parent
 382          * here. However, it may turn out that we've
 383          * reached this commit some other way (where it
 384          * wasn't uninteresting), in which case we need
 385          * to mark its parents recursively too..
 386          */
 387         if (commit->object.flags & UNINTERESTING) {
 388                 while (parent) {
 389                         struct commit *p = parent->item;
 390                         parent = parent->next;
 391                         parse_commit(p);
 392                         p->object.flags |= UNINTERESTING;
 393                         if (p->parents)
 394                                 mark_parents_uninteresting(p);
 395                         if (p->object.flags & SEEN)
 396                                 continue;
 397                         p->object.flags |= SEEN;
 398                         insert_by_date(p, list);
 399                 }
 400                 return;
 401         }
 402
 403         /*
 404          * Ok, the commit wasn't uninteresting. Try to
 405          * simplify the commit history and find the parent
 406          * that has no differences in the path set if one exists.
 407          */
 408         if (revs->prune_fn)
 409                 revs->prune_fn(revs, commit);
 410
 411         if (revs->no_walk)
 412                 return;
 413
 414         left_flag = (commit->object.flags & SYMMETRIC_LEFT);
 415
 416         rest = !revs->first_parent_only;
 417         for (parent = commit->parents, add = 1; parent; add = rest) {
 418                 struct commit *p = parent->item;
 419
 420                 parent = parent->next;
 421                 parse_commit(p);
 422                 p->object.flags |= left_flag;
 423                 if (p->object.flags & SEEN)
 424                         continue;
 425                 p->object.flags |= SEEN;
 426                 if (add)
 427                         insert_by_date(p, list);
 428         }
 429 }
 430
 431 static void cherry_pick_list(struct commit_list *list)
 432 {
 433         struct commit_list *p;
 434         int left_count = 0, right_count = 0;
 435         int left_first;
 436         struct patch_ids ids;
 437
 438         /* First count the commits on the left and on the right */
 439         for (p = list; p; p = p->next) {
 440                 struct commit *commit = p->item;
 441                 unsigned flags = commit->object.flags;
 442                 if (flags & BOUNDARY)
 443                         ;
 444                 else if (flags & SYMMETRIC_LEFT)
 445                         left_count++;
 446                 else
 447                         right_count++;
 448         }
 449
 450         left_first = left_count < right_count;
 451         init_patch_ids(&ids);
 452
 453         /* Compute patch-ids for one side */
 454         for (p = list; p; p = p->next) {
 455                 struct commit *commit = p->item;
 456                 unsigned flags = commit->object.flags;
 457
 458                 if (flags & BOUNDARY)
 459                         continue;
 460                 /*
 461                  * If we have fewer left, left_first is set and we omit
 462                  * commits on the right branch in this loop.  If we have
 463                  * fewer right, we skip the left ones.
 464                  */
 465                 if (left_first != !!(flags & SYMMETRIC_LEFT))
 466                         continue;
 467                 commit->util = add_commit_patch_id(commit, &ids);
 468         }
 469
 470         /* Check the other side */
 471         for (p = list; p; p = p->next) {
 472                 struct commit *commit = p->item;
 473                 struct patch_id *id;
 474                 unsigned flags = commit->object.flags;
 475
 476                 if (flags & BOUNDARY)
 477                         continue;
 478                 /*
 479                  * If we have fewer left, left_first is set and we omit
 480                  * commits on the left branch in this loop.
 481                  */
 482                 if (left_first == !!(flags & SYMMETRIC_LEFT))
 483                         continue;
 484
 485                 /*
 486                  * Have we seen the same patch id?
 487                  */
 488                 id = has_commit_patch_id(commit, &ids);
 489                 if (!id)
 490                         continue;
 491                 id->seen = 1;
 492                 commit->object.flags |= SHOWN;
 493         }
 494
 495         /* Now check the original side for seen ones */
 496         for (p = list; p; p = p->next) {
 497                 struct commit *commit = p->item;
 498                 struct patch_id *ent;
 499
 500                 ent = commit->util;
 501                 if (!ent)
 502                         continue;
 503                 if (ent->seen)
 504                         commit->object.flags |= SHOWN;
 505                 commit->util = NULL;
 506         }
 507
 508         free_patch_ids(&ids);
 509 }
 510
 511 static void limit_list(struct rev_info *revs)
 512 {
 513         struct commit_list *list = revs->commits;
 514         struct commit_list *newlist = NULL;
 515         struct commit_list **p = &newlist;
 516
 517         while (list) {
 518                 struct commit_list *entry = list;
 519                 struct commit *commit = list->item;
 520                 struct object *obj = &commit->object;
 521
 522                 list = list->next;
 523                 free(entry);
 524
 525                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 526                         obj->flags |= UNINTERESTING;
 527                 add_parents_to_list(revs, commit, &list);
 528                 if (obj->flags & UNINTERESTING) {
 529                         mark_parents_uninteresting(commit);
 530                         if (everybody_uninteresting(list))
 531                                 break;
 532                         continue;
 533                 }
 534                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 535                         continue;
 536                 p = &commit_list_insert(commit, p)->next;
 537         }
 538         if (revs->cherry_pick)
 539                 cherry_pick_list(newlist);
 540
 541         revs->commits = newlist;
 542 }
 543
 544 struct all_refs_cb {
 545         int all_flags;
 546         int warned_bad_reflog;
 547         struct rev_info *all_revs;
 548         const char *name_for_errormsg;
 549 };
 550
 551 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 552 {
 553         struct all_refs_cb *cb = cb_data;
 554         struct object *object = get_reference(cb->all_revs, path, sha1,
 555                                               cb->all_flags);
 556         add_pending_object(cb->all_revs, object, path);
 557         return 0;
 558 }
 559
 560 static void handle_all(struct rev_info *revs, unsigned flags)
 561 {
 562         struct all_refs_cb cb;
 563         cb.all_revs = revs;
 564         cb.all_flags = flags;
 565         for_each_ref(handle_one_ref, &cb);
 566 }
 567
 568 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 569 {
 570         struct all_refs_cb *cb = cb_data;
 571         if (!is_null_sha1(sha1)) {
 572                 struct object *o = parse_object(sha1);
 573                 if (o) {
 574                         o->flags |= cb->all_flags;
 575                         add_pending_object(cb->all_revs, o, "");
 576                 }
 577                 else if (!cb->warned_bad_reflog) {
 578                         warning("reflog of '%s' references pruned commits",
 579                                 cb->name_for_errormsg);
 580                         cb->warned_bad_reflog = 1;
 581                 }
 582         }
 583 }
 584
 585 static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 586                 const char *email, unsigned long timestamp, int tz,
 587                 const char *message, void *cb_data)
 588 {
 589         handle_one_reflog_commit(osha1, cb_data);
 590         handle_one_reflog_commit(nsha1, cb_data);
 591         return 0;
 592 }
 593
 594 static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 595 {
 596         struct all_refs_cb *cb = cb_data;
 597         cb->warned_bad_reflog = 0;
 598         cb->name_for_errormsg = path;
 599         for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
 600         return 0;
 601 }
 602
 603 static void handle_reflog(struct rev_info *revs, unsigned flags)
 604 {
 605         struct all_refs_cb cb;
 606         cb.all_revs = revs;
 607         cb.all_flags = flags;
 608         for_each_reflog(handle_one_reflog, &cb);
 609 }
 610
 611 static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 612 {
 613         unsigned char sha1[20];
 614         struct object *it;
 615         struct commit *commit;
 616         struct commit_list *parents;
 617
 618         if (*arg == '^') {
 619                 flags ^= UNINTERESTING;
 620                 arg++;
 621         }
 622         if (get_sha1(arg, sha1))
 623                 return 0;
 624         while (1) {
 625                 it = get_reference(revs, arg, sha1, 0);
 626                 if (it->type != OBJ_TAG)
 627                         break;
 628                 hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
 629         }
 630         if (it->type != OBJ_COMMIT)
 631                 return 0;
 632         commit = (struct commit *)it;
 633         for (parents = commit->parents; parents; parents = parents->next) {
 634                 it = &parents->item->object;
 635                 it->flags |= flags;
 636                 add_pending_object(revs, it, arg);
 637         }
 638         return 1;
 639 }
 640
 641 void init_revisions(struct rev_info *revs, const char *prefix)
 642 {
 643         memset(revs, 0, sizeof(*revs));
 644
 645         revs->abbrev = DEFAULT_ABBREV;
 646         revs->ignore_merges = 1;
 647         revs->simplify_history = 1;
 648         revs->pruning.recursive = 1;
 649         revs->pruning.quiet = 1;
 650         revs->pruning.add_remove = file_add_remove;
 651         revs->pruning.change = file_change;
 652         revs->lifo = 1;
 653         revs->dense = 1;
 654         revs->prefix = prefix;
 655         revs->max_age = -1;
 656         revs->min_age = -1;
 657         revs->skip_count = -1;
 658         revs->max_count = -1;
 659         revs->subject_prefix = "PATCH";
 660
 661         revs->prune_fn = NULL;
 662         revs->prune_data = NULL;
 663
 664         revs->topo_setter = topo_sort_default_setter;
 665         revs->topo_getter = topo_sort_default_getter;
 666
 667         revs->commit_format = CMIT_FMT_DEFAULT;
 668
 669         diff_setup(&revs->diffopt);
 670 }
 671
 672 static void add_pending_commit_list(struct rev_info *revs,
 673                                     struct commit_list *commit_list,
 674                                     unsigned int flags)
 675 {
 676         while (commit_list) {
 677                 struct object *object = &commit_list->item->object;
 678                 object->flags |= flags;
 679                 add_pending_object(revs, object, sha1_to_hex(object->sha1));
 680                 commit_list = commit_list->next;
 681         }
 682 }
 683
 684 static void prepare_show_merge(struct rev_info *revs)
 685 {
 686         struct commit_list *bases;
 687         struct commit *head, *other;
 688         unsigned char sha1[20];
 689         const char **prune = NULL;
 690         int i, prune_num = 1; /* counting terminating NULL */
 691
 692         if (get_sha1("HEAD", sha1) || !(head = lookup_commit(sha1)))
 693                 die("--merge without HEAD?");
 694         if (get_sha1("MERGE_HEAD", sha1) || !(other = lookup_commit(sha1)))
 695                 die("--merge without MERGE_HEAD?");
 696         add_pending_object(revs, &head->object, "HEAD");
 697         add_pending_object(revs, &other->object, "MERGE_HEAD");
 698         bases = get_merge_bases(head, other, 1);
 699         while (bases) {
 700                 struct commit *it = bases->item;
 701                 struct commit_list *n = bases->next;
 702                 free(bases);
 703                 bases = n;
 704                 it->object.flags |= UNINTERESTING;
 705                 add_pending_object(revs, &it->object, "(merge-base)");
 706         }
 707
 708         if (!active_nr)
 709                 read_cache();
 710         for (i = 0; i < active_nr; i++) {
 711                 struct cache_entry *ce = active_cache[i];
 712                 if (!ce_stage(ce))
 713                         continue;
 714                 if (ce_path_match(ce, revs->prune_data)) {
 715                         prune_num++;
 716                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
 717                         prune[prune_num-2] = ce->name;
 718                         prune[prune_num-1] = NULL;
 719                 }
 720                 while ((i+1 < active_nr) &&
 721                        ce_same_name(ce, active_cache[i+1]))
 722                         i++;
 723         }
 724         revs->prune_data = prune;
 725 }
 726
 727 int handle_revision_arg(const char *arg, struct rev_info *revs,
 728                         int flags,
 729                         int cant_be_filename)
 730 {
 731         unsigned mode;
 732         char *dotdot;
 733         struct object *object;
 734         unsigned char sha1[20];
 735         int local_flags;
 736
 737         dotdot = strstr(arg, "..");
 738         if (dotdot) {
 739                 unsigned char from_sha1[20];
 740                 const char *next = dotdot + 2;
 741                 const char *this = arg;
 742                 int symmetric = *next == '.';
 743                 unsigned int flags_exclude = flags ^ UNINTERESTING;
 744
 745                 *dotdot = 0;
 746                 next += symmetric;
 747
 748                 if (!*next)
 749                         next = "HEAD";
 750                 if (dotdot == arg)
 751                         this = "HEAD";
 752                 if (!get_sha1(this, from_sha1) &&
 753                     !get_sha1(next, sha1)) {
 754                         struct commit *a, *b;
 755                         struct commit_list *exclude;
 756
 757                         a = lookup_commit_reference(from_sha1);
 758                         b = lookup_commit_reference(sha1);
 759                         if (!a || !b) {
 760                                 die(symmetric ?
 761                                     "Invalid symmetric difference expression %s...%s" :
 762                                     "Invalid revision range %s..%s",
 763                                     arg, next);
 764                         }
 765
 766                         if (!cant_be_filename) {
 767                                 *dotdot = '.';
 768                                 verify_non_filename(revs->prefix, arg);
 769                         }
 770
 771                         if (symmetric) {
 772                                 exclude = get_merge_bases(a, b, 1);
 773                                 add_pending_commit_list(revs, exclude,
 774                                                         flags_exclude);
 775                                 free_commit_list(exclude);
 776                                 a->object.flags |= flags | SYMMETRIC_LEFT;
 777                         } else
 778                                 a->object.flags |= flags_exclude;
 779                         b->object.flags |= flags;
 780                         add_pending_object(revs, &a->object, this);
 781                         add_pending_object(revs, &b->object, next);
 782                         return 0;
 783                 }
 784                 *dotdot = '.';
 785         }
 786         dotdot = strstr(arg, "^@");
 787         if (dotdot && !dotdot[2]) {
 788                 *dotdot = 0;
 789                 if (add_parents_only(revs, arg, flags))
 790                         return 0;
 791                 *dotdot = '^';
 792         }
 793         dotdot = strstr(arg, "^!");
 794         if (dotdot && !dotdot[2]) {
 795                 *dotdot = 0;
 796                 if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
 797                         *dotdot = '^';
 798         }
 799
 800         local_flags = 0;
 801         if (*arg == '^') {
 802                 local_flags = UNINTERESTING;
 803                 arg++;
 804         }
 805         if (get_sha1_with_mode(arg, sha1, &mode))
 806                 return -1;
 807         if (!cant_be_filename)
 808                 verify_non_filename(revs->prefix, arg);
 809         object = get_reference(revs, arg, sha1, flags ^ local_flags);
 810         add_pending_object_with_mode(revs, object, arg, mode);
 811         return 0;
 812 }
 813
 814 static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
 815 {
 816         if (!revs->grep_filter) {
 817                 struct grep_opt *opt = xcalloc(1, sizeof(*opt));
 818                 opt->status_only = 1;
 819                 opt->pattern_tail = &(opt->pattern_list);
 820                 opt->regflags = REG_NEWLINE;
 821                 revs->grep_filter = opt;
 822         }
 823         append_grep_pattern(revs->grep_filter, ptn,
 824                             "command line", 0, what);
 825 }
 826
 827 static void add_header_grep(struct rev_info *revs, const char *field, const char *pattern)
 828 {
 829         char *pat;
 830         const char *prefix;
 831         int patlen, fldlen;
 832
 833         fldlen = strlen(field);
 834         patlen = strlen(pattern);
 835         pat = xmalloc(patlen + fldlen + 10);
 836         prefix = ".*";
 837         if (*pattern == '^') {
 838                 prefix = "";
 839                 pattern++;
 840         }
 841         sprintf(pat, "^%s %s%s", field, prefix, pattern);
 842         add_grep(revs, pat, GREP_PATTERN_HEAD);
 843 }
 844
 845 static void add_message_grep(struct rev_info *revs, const char *pattern)
 846 {
 847         add_grep(revs, pattern, GREP_PATTERN_BODY);
 848 }
 849
 850 static void add_ignore_packed(struct rev_info *revs, const char *name)
 851 {
 852         int num = ++revs->num_ignore_packed;
 853
 854         revs->ignore_packed = xrealloc(revs->ignore_packed,
 855                                        sizeof(const char **) * (num + 1));
 856         revs->ignore_packed[num-1] = name;
 857         revs->ignore_packed[num] = NULL;
 858 }
 859
 860 /*
 861  * Parse revision information, filling in the "rev_info" structure,
 862  * and removing the used arguments from the argument list.
 863  *
 864  * Returns the number of arguments left that weren't recognized
 865  * (which are also moved to the head of the argument list)
 866  */
 867 int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
 868 {
 869         int i, flags, seen_dashdash, show_merge;
 870         const char **unrecognized = argv + 1;
 871         int left = 1;
 872         int all_match = 0;
 873
 874         /* First, search for "--" */
 875         seen_dashdash = 0;
 876         for (i = 1; i < argc; i++) {
 877                 const char *arg = argv[i];
 878                 if (strcmp(arg, "--"))
 879                         continue;
 880                 argv[i] = NULL;
 881                 argc = i;
 882                 revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
 883                 seen_dashdash = 1;
 884                 break;
 885         }
 886
 887         flags = show_merge = 0;
 888         for (i = 1; i < argc; i++) {
 889                 const char *arg = argv[i];
 890                 if (*arg == '-') {
 891                         int opts;
 892                         if (!prefixcmp(arg, "--max-count=")) {
 893                                 revs->max_count = atoi(arg + 12);
 894                                 continue;
 895                         }
 896                         if (!prefixcmp(arg, "--skip=")) {
 897                                 revs->skip_count = atoi(arg + 7);
 898                                 continue;
 899                         }
 900                         /* accept -<digit>, like traditional "head" */
 901                         if ((*arg == '-') && isdigit(arg[1])) {
 902                                 revs->max_count = atoi(arg + 1);
 903                                 continue;
 904                         }
 905                         if (!strcmp(arg, "-n")) {
 906                                 if (argc <= i + 1)
 907                                         die("-n requires an argument");
 908                                 revs->max_count = atoi(argv[++i]);
 909                                 continue;
 910                         }
 911                         if (!prefixcmp(arg, "-n")) {
 912                                 revs->max_count = atoi(arg + 2);
 913                                 continue;
 914                         }
 915                         if (!prefixcmp(arg, "--max-age=")) {
 916                                 revs->max_age = atoi(arg + 10);
 917                                 continue;
 918                         }
 919                         if (!prefixcmp(arg, "--since=")) {
 920                                 revs->max_age = approxidate(arg + 8);
 921                                 continue;
 922                         }
 923                         if (!prefixcmp(arg, "--after=")) {
 924                                 revs->max_age = approxidate(arg + 8);
 925                                 continue;
 926                         }
 927                         if (!prefixcmp(arg, "--min-age=")) {
 928                                 revs->min_age = atoi(arg + 10);
 929                                 continue;
 930                         }
 931                         if (!prefixcmp(arg, "--before=")) {
 932                                 revs->min_age = approxidate(arg + 9);
 933                                 continue;
 934                         }
 935                         if (!prefixcmp(arg, "--until=")) {
 936                                 revs->min_age = approxidate(arg + 8);
 937                                 continue;
 938                         }
 939                         if (!strcmp(arg, "--all")) {
 940                                 handle_all(revs, flags);
 941                                 continue;
 942                         }
 943                         if (!strcmp(arg, "--first-parent")) {
 944                                 revs->first_parent_only = 1;
 945                                 continue;
 946                         }
 947                         if (!strcmp(arg, "--reflog")) {
 948                                 handle_reflog(revs, flags);
 949                                 continue;
 950                         }
 951                         if (!strcmp(arg, "-g") ||
 952                                         !strcmp(arg, "--walk-reflogs")) {
 953                                 init_reflog_walk(&revs->reflog_info);
 954                                 continue;
 955                         }
 956                         if (!strcmp(arg, "--not")) {
 957                                 flags ^= UNINTERESTING;
 958                                 continue;
 959                         }
 960                         if (!strcmp(arg, "--default")) {
 961                                 if (++i >= argc)
 962                                         die("bad --default argument");
 963                                 def = argv[i];
 964                                 continue;
 965                         }
 966                         if (!strcmp(arg, "--merge")) {
 967                                 show_merge = 1;
 968                                 continue;
 969                         }
 970                         if (!strcmp(arg, "--topo-order")) {
 971                                 revs->topo_order = 1;
 972                                 continue;
 973                         }
 974                         if (!strcmp(arg, "--date-order")) {
 975                                 revs->lifo = 0;
 976                                 revs->topo_order = 1;
 977                                 continue;
 978                         }
 979                         if (!strcmp(arg, "--parents")) {
 980                                 revs->parents = 1;
 981                                 continue;
 982                         }
 983                         if (!strcmp(arg, "--dense")) {
 984                                 revs->dense = 1;
 985                                 continue;
 986                         }
 987                         if (!strcmp(arg, "--sparse")) {
 988                                 revs->dense = 0;
 989                                 continue;
 990                         }
 991                         if (!strcmp(arg, "--remove-empty")) {
 992                                 revs->remove_empty_trees = 1;
 993                                 continue;
 994                         }
 995                         if (!strcmp(arg, "--no-merges")) {
 996                                 revs->no_merges = 1;
 997                                 continue;
 998                         }
 999                         if (!strcmp(arg, "--boundary")) {
1000                                 revs->boundary = 1;
1001                                 continue;
1002                         }
1003                         if (!strcmp(arg, "--left-right")) {
1004                                 revs->left_right = 1;
1005                                 continue;
1006                         }
1007                         if (!strcmp(arg, "--cherry-pick")) {
1008                                 revs->cherry_pick = 1;
1009                                 continue;
1010                         }
1011                         if (!strcmp(arg, "--objects")) {
1012                                 revs->tag_objects = 1;
1013                                 revs->tree_objects = 1;
1014                                 revs->blob_objects = 1;
1015                                 continue;
1016                         }
1017                         if (!strcmp(arg, "--objects-edge")) {
1018                                 revs->tag_objects = 1;
1019                                 revs->tree_objects = 1;
1020                                 revs->blob_objects = 1;
1021                                 revs->edge_hint = 1;
1022                                 continue;
1023                         }
1024                         if (!strcmp(arg, "--unpacked")) {
1025                                 revs->unpacked = 1;
1026                                 free(revs->ignore_packed);
1027                                 revs->ignore_packed = NULL;
1028                                 revs->num_ignore_packed = 0;
1029                                 continue;
1030                         }
1031                         if (!prefixcmp(arg, "--unpacked=")) {
1032                                 revs->unpacked = 1;
1033                                 add_ignore_packed(revs, arg+11);
1034                                 continue;
1035                         }
1036                         if (!strcmp(arg, "-r")) {
1037                                 revs->diff = 1;
1038                                 revs->diffopt.recursive = 1;
1039                                 continue;
1040                         }
1041                         if (!strcmp(arg, "-t")) {
1042                                 revs->diff = 1;
1043                                 revs->diffopt.recursive = 1;
1044                                 revs->diffopt.tree_in_recursive = 1;
1045                                 continue;
1046                         }
1047                         if (!strcmp(arg, "-m")) {
1048                                 revs->ignore_merges = 0;
1049                                 continue;
1050                         }
1051                         if (!strcmp(arg, "-c")) {
1052                                 revs->diff = 1;
1053                                 revs->dense_combined_merges = 0;
1054                                 revs->combine_merges = 1;
1055                                 continue;
1056                         }
1057                         if (!strcmp(arg, "--cc")) {
1058                                 revs->diff = 1;
1059                                 revs->dense_combined_merges = 1;
1060                                 revs->combine_merges = 1;
1061                                 continue;
1062                         }
1063                         if (!strcmp(arg, "-v")) {
1064                                 revs->verbose_header = 1;
1065                                 continue;
1066                         }
1067                         if (!prefixcmp(arg, "--pretty")) {
1068                                 revs->verbose_header = 1;
1069                                 revs->commit_format = get_commit_format(arg+8);
1070                                 continue;
1071                         }
1072                         if (!strcmp(arg, "--root")) {
1073                                 revs->show_root_diff = 1;
1074                                 continue;
1075                         }
1076                         if (!strcmp(arg, "--no-commit-id")) {
1077                                 revs->no_commit_id = 1;
1078                                 continue;
1079                         }
1080                         if (!strcmp(arg, "--always")) {
1081                                 revs->always_show_header = 1;
1082                                 continue;
1083                         }
1084                         if (!strcmp(arg, "--no-abbrev")) {
1085                                 revs->abbrev = 0;
1086                                 continue;
1087                         }
1088                         if (!strcmp(arg, "--abbrev")) {
1089                                 revs->abbrev = DEFAULT_ABBREV;
1090                                 continue;
1091                         }
1092                         if (!prefixcmp(arg, "--abbrev=")) {
1093                                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1094                                 if (revs->abbrev < MINIMUM_ABBREV)
1095                                         revs->abbrev = MINIMUM_ABBREV;
1096                                 else if (revs->abbrev > 40)
1097                                         revs->abbrev = 40;
1098                                 continue;
1099                         }
1100                         if (!strcmp(arg, "--abbrev-commit")) {
1101                                 revs->abbrev_commit = 1;
1102                                 continue;
1103                         }
1104                         if (!strcmp(arg, "--full-diff")) {
1105                                 revs->diff = 1;
1106                                 revs->full_diff = 1;
1107                                 continue;
1108                         }
1109                         if (!strcmp(arg, "--full-history")) {
1110                                 revs->simplify_history = 0;
1111                                 continue;
1112                         }
1113                         if (!strcmp(arg, "--relative-date")) {
1114                                 revs->relative_date = 1;
1115                                 continue;
1116                         }
1117
1118                         /*
1119                          * Grepping the commit log
1120                          */
1121                         if (!prefixcmp(arg, "--author=")) {
1122                                 add_header_grep(revs, "author", arg+9);
1123                                 continue;
1124                         }
1125                         if (!prefixcmp(arg, "--committer=")) {
1126                                 add_header_grep(revs, "committer", arg+12);
1127                                 continue;
1128                         }
1129                         if (!prefixcmp(arg, "--grep=")) {
1130                                 add_message_grep(revs, arg+7);
1131                                 continue;
1132                         }
1133                         if (!strcmp(arg, "--all-match")) {
1134                                 all_match = 1;
1135                                 continue;
1136                         }
1137                         if (!prefixcmp(arg, "--encoding=")) {
1138                                 arg += 11;
1139                                 if (strcmp(arg, "none"))
1140                                         git_log_output_encoding = xstrdup(arg);
1141                                 else
1142                                         git_log_output_encoding = "";
1143                                 continue;
1144                         }
1145                         if (!strcmp(arg, "--reverse")) {
1146                                 revs->reverse ^= 1;
1147                                 continue;
1148                         }
1149
1150                         opts = diff_opt_parse(&revs->diffopt, argv+i, argc-i);
1151                         if (opts > 0) {
1152                                 revs->diff = 1;
1153                                 i += opts - 1;
1154                                 continue;
1155                         }
1156                         *unrecognized++ = arg;
1157                         left++;
1158                         continue;
1159                 }
1160
1161                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1162                         int j;
1163                         if (seen_dashdash || *arg == '^')
1164                                 die("bad revision '%s'", arg);
1165
1166                         /* If we didn't have a "--":
1167                          * (1) all filenames must exist;
1168                          * (2) all rev-args must not be interpretable
1169                          *     as a valid filename.
1170                          * but the latter we have checked in the main loop.
1171                          */
1172                         for (j = i; j < argc; j++)
1173                                 verify_filename(revs->prefix, argv[j]);
1174
1175                         revs->prune_data = get_pathspec(revs->prefix,
1176                                                         argv + i);
1177                         break;
1178                 }
1179         }
1180
1181         if (show_merge)
1182                 prepare_show_merge(revs);
1183         if (def && !revs->pending.nr) {
1184                 unsigned char sha1[20];
1185                 struct object *object;
1186                 unsigned mode;
1187                 if (get_sha1_with_mode(def, sha1, &mode))
1188                         die("bad default revision '%s'", def);
1189                 object = get_reference(revs, def, sha1, 0);
1190                 add_pending_object_with_mode(revs, object, def, mode);
1191         }
1192
1193         if (revs->topo_order)
1194                 revs->limited = 1;
1195
1196         if (revs->prune_data) {
1197                 diff_tree_setup_paths(revs->prune_data, &revs->pruning);
1198                 revs->prune_fn = try_to_simplify_commit;
1199                 if (!revs->full_diff)
1200                         diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
1201         }
1202         if (revs->combine_merges) {
1203                 revs->ignore_merges = 0;
1204                 if (revs->dense_combined_merges && !revs->diffopt.output_format)
1205                         revs->diffopt.output_format = DIFF_FORMAT_PATCH;
1206         }
1207         revs->diffopt.abbrev = revs->abbrev;
1208         if (diff_setup_done(&revs->diffopt) < 0)
1209                 die("diff_setup_done failed");
1210
1211         if (revs->grep_filter) {
1212                 revs->grep_filter->all_match = all_match;
1213                 compile_grep_patterns(revs->grep_filter);
1214         }
1215
1216         return left;
1217 }
1218
1219 void prepare_revision_walk(struct rev_info *revs)
1220 {
1221         int nr = revs->pending.nr;
1222         struct object_array_entry *e, *list;
1223
1224         e = list = revs->pending.objects;
1225         revs->pending.nr = 0;
1226         revs->pending.alloc = 0;
1227         revs->pending.objects = NULL;
1228         while (--nr >= 0) {
1229                 struct commit *commit = handle_commit(revs, e->item, e->name);
1230                 if (commit) {
1231                         if (!(commit->object.flags & SEEN)) {
1232                                 commit->object.flags |= SEEN;
1233                                 insert_by_date(commit, &revs->commits);
1234                         }
1235                 }
1236                 e++;
1237         }
1238         free(list);
1239
1240         if (revs->no_walk)
1241                 return;
1242         if (revs->limited)
1243                 limit_list(revs);
1244         if (revs->topo_order)
1245                 sort_in_topological_order_fn(&revs->commits, revs->lifo,
1246                                              revs->topo_setter,
1247                                              revs->topo_getter);
1248 }
1249
1250 static int rewrite_one(struct rev_info *revs, struct commit **pp)
1251 {
1252         for (;;) {
1253                 struct commit *p = *pp;
1254                 if (!revs->limited)
1255                         add_parents_to_list(revs, p, &revs->commits);
1256                 if (p->parents && p->parents->next)
1257                         return 0;
1258                 if (p->object.flags & (TREECHANGE | UNINTERESTING))
1259                         return 0;
1260                 if (!p->parents)
1261                         return -1;
1262                 *pp = p->parents->item;
1263         }
1264 }
1265
1266 static void rewrite_parents(struct rev_info *revs, struct commit *commit)
1267 {
1268         struct commit_list **pp = &commit->parents;
1269         while (*pp) {
1270                 struct commit_list *parent = *pp;
1271                 if (rewrite_one(revs, &parent->item) < 0) {
1272                         *pp = parent->next;
1273                         continue;
1274                 }
1275                 pp = &parent->next;
1276         }
1277 }
1278
1279 static int commit_match(struct commit *commit, struct rev_info *opt)
1280 {
1281         if (!opt->grep_filter)
1282                 return 1;
1283         return grep_buffer(opt->grep_filter,
1284                            NULL, /* we say nothing, not even filename */
1285                            commit->buffer, strlen(commit->buffer));
1286 }
1287
1288 static struct commit *get_revision_1(struct rev_info *revs)
1289 {
1290         if (!revs->commits)
1291                 return NULL;
1292
1293         do {
1294                 struct commit_list *entry = revs->commits;
1295                 struct commit *commit = entry->item;
1296
1297                 revs->commits = entry->next;
1298                 free(entry);
1299
1300                 if (revs->reflog_info)
1301                         fake_reflog_parent(revs->reflog_info, commit);
1302
1303                 /*
1304                  * If we haven't done the list limiting, we need to look at
1305                  * the parents here. We also need to do the date-based limiting
1306                  * that we'd otherwise have done in limit_list().
1307                  */
1308                 if (!revs->limited) {
1309                         if (revs->max_age != -1 &&
1310                             (commit->date < revs->max_age))
1311                                 continue;
1312                         add_parents_to_list(revs, commit, &revs->commits);
1313                 }
1314                 if (commit->object.flags & SHOWN)
1315                         continue;
1316
1317                 if (revs->unpacked && has_sha1_pack(commit->object.sha1,
1318                                                     revs->ignore_packed))
1319                     continue;
1320
1321                 if (commit->object.flags & UNINTERESTING)
1322                         continue;
1323                 if (revs->min_age != -1 && (commit->date > revs->min_age))
1324                         continue;
1325                 if (revs->no_merges &&
1326                     commit->parents && commit->parents->next)
1327                         continue;
1328                 if (!commit_match(commit, revs))
1329                         continue;
1330                 if (revs->prune_fn && revs->dense) {
1331                         /* Commit without changes? */
1332                         if (!(commit->object.flags & TREECHANGE)) {
1333                                 /* drop merges unless we want parenthood */
1334                                 if (!revs->parents)
1335                                         continue;
1336                                 /* non-merge - always ignore it */
1337                                 if (!commit->parents || !commit->parents->next)
1338                                         continue;
1339                         }
1340                         if (revs->parents)
1341                                 rewrite_parents(revs, commit);
1342                 }
1343                 return commit;
1344         } while (revs->commits);
1345         return NULL;
1346 }
1347
1348 static void gc_boundary(struct object_array *array)
1349 {
1350         unsigned nr = array->nr;
1351         unsigned alloc = array->alloc;
1352         struct object_array_entry *objects = array->objects;
1353
1354         if (alloc <= nr) {
1355                 unsigned i, j;
1356                 for (i = j = 0; i < nr; i++) {
1357                         if (objects[i].item->flags & SHOWN)
1358                                 continue;
1359                         if (i != j)
1360                                 objects[j] = objects[i];
1361                         j++;
1362                 }
1363                 for (i = j; i < nr; i++)
1364                         objects[i].item = NULL;
1365                 array->nr = j;
1366         }
1367 }
1368
1369 struct commit *get_revision(struct rev_info *revs)
1370 {
1371         struct commit *c = NULL;
1372         struct commit_list *l;
1373
1374         if (revs->boundary == 2) {
1375                 unsigned i;
1376                 struct object_array *array = &revs->boundary_commits;
1377                 struct object_array_entry *objects = array->objects;
1378                 for (i = 0; i < array->nr; i++) {
1379                         c = (struct commit *)(objects[i].item);
1380                         if (!c)
1381                                 continue;
1382                         if (!(c->object.flags & CHILD_SHOWN))
1383                                 continue;
1384                         if (!(c->object.flags & SHOWN))
1385                                 break;
1386                 }
1387                 if (array->nr <= i)
1388                         return NULL;
1389
1390                 c->object.flags |= SHOWN | BOUNDARY;
1391                 return c;
1392         }
1393
1394         if (revs->reverse) {
1395                 int limit = -1;
1396
1397                 if (0 <= revs->max_count) {
1398                         limit = revs->max_count;
1399                         if (0 < revs->skip_count)
1400                                 limit += revs->skip_count;
1401                 }
1402                 l = NULL;
1403                 while ((c = get_revision_1(revs))) {
1404                         commit_list_insert(c, &l);
1405                         if ((0 < limit) && !--limit)
1406                                 break;
1407                 }
1408                 revs->commits = l;
1409                 revs->reverse = 0;
1410                 revs->max_count = -1;
1411                 c = NULL;
1412         }
1413
1414         /*
1415          * Now pick up what they want to give us
1416          */
1417         c = get_revision_1(revs);
1418         if (c) {
1419                 while (0 < revs->skip_count) {
1420                         revs->skip_count--;
1421                         c = get_revision_1(revs);
1422                         if (!c)
1423                                 break;
1424                 }
1425         }
1426
1427         /*
1428          * Check the max_count.
1429          */
1430         switch (revs->max_count) {
1431         case -1:
1432                 break;
1433         case 0:
1434                 c = NULL;
1435                 break;
1436         default:
1437                 revs->max_count--;
1438         }
1439
1440         if (c)
1441                 c->object.flags |= SHOWN;
1442
1443         if (!revs->boundary) {
1444                 return c;
1445         }
1446
1447         if (!c) {
1448                 /*
1449                  * get_revision_1() runs out the commits, and
1450                  * we are done computing the boundaries.
1451                  * switch to boundary commits output mode.
1452                  */
1453                 revs->boundary = 2;
1454                 return get_revision(revs);
1455         }
1456
1457         /*
1458          * boundary commits are the commits that are parents of the
1459          * ones we got from get_revision_1() but they themselves are
1460          * not returned from get_revision_1().  Before returning
1461          * 'c', we need to mark its parents that they could be boundaries.
1462          */
1463
1464         for (l = c->parents; l; l = l->next) {
1465                 struct object *p;
1466                 p = &(l->item->object);
1467                 if (p->flags & (CHILD_SHOWN | SHOWN))
1468                         continue;
1469                 p->flags |= CHILD_SHOWN;
1470                 gc_boundary(&revs->boundary_commits);
1471                 add_object_array(p, NULL, &revs->boundary_commits);
1472         }
1473
1474         return c;
1475 }