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                 if (parse_commit(p) < 0)
 322                         die("cannot simplify commit %s (because of %s)",
 323                             sha1_to_hex(commit->object.sha1),
 324                             sha1_to_hex(p->object.sha1));
 325                 switch (rev_compare_tree(revs, p->tree, commit->tree)) {
 326                 case REV_TREE_SAME:
 327                         tree_same = 1;
 328                         if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
 329                                 /* Even if a merge with an uninteresting
 330                                  * side branch brought the entire change
 331                                  * we are interested in, we do not want
 332                                  * to lose the other branches of this
 333                                  * merge, so we just keep going.
 334                                  */
 335                                 pp = &parent->next;
 336                                 continue;
 337                         }
 338                         parent->next = NULL;
 339                         commit->parents = parent;
 340                         return;
 341
 342                 case REV_TREE_NEW:
 343                         if (revs->remove_empty_trees &&
 344                             rev_same_tree_as_empty(revs, p->tree)) {
 345                                 /* We are adding all the specified
 346                                  * paths from this parent, so the
 347                                  * history beyond this parent is not
 348                                  * interesting.  Remove its parents
 349                                  * (they are grandparents for us).
 350                                  * IOW, we pretend this parent is a
 351                                  * "root" commit.
 352                                  */
 353                                 if (parse_commit(p) < 0)
 354                                         die("cannot simplify commit %s (invalid %s)",
 355                                             sha1_to_hex(commit->object.sha1),
 356                                             sha1_to_hex(p->object.sha1));
 357                                 p->parents = NULL;
 358                         }
 359                 /* fallthrough */
 360                 case REV_TREE_DIFFERENT:
 361                         tree_changed = 1;
 362                         pp = &parent->next;
 363                         continue;
 364                 }
 365                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 366         }
 367         if (tree_changed && !tree_same)
 368                 commit->object.flags |= TREECHANGE;
 369 }
 370
 371 static int add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 372 {
 373         struct commit_list *parent = commit->parents;
 374         unsigned left_flag;
 375         int add, rest;
 376
 377         if (commit->object.flags & ADDED)
 378                 return 0;
 379         commit->object.flags |= ADDED;
 380
 381         /*
 382          * If the commit is uninteresting, don't try to
 383          * prune parents - we want the maximal uninteresting
 384          * set.
 385          *
 386          * Normally we haven't parsed the parent
 387          * yet, so we won't have a parent of a parent
 388          * here. However, it may turn out that we've
 389          * reached this commit some other way (where it
 390          * wasn't uninteresting), in which case we need
 391          * to mark its parents recursively too..
 392          */
 393         if (commit->object.flags & UNINTERESTING) {
 394                 while (parent) {
 395                         struct commit *p = parent->item;
 396                         parent = parent->next;
 397                         if (parse_commit(p) < 0)
 398                                 return -1;
 399                         p->object.flags |= UNINTERESTING;
 400                         if (p->parents)
 401                                 mark_parents_uninteresting(p);
 402                         if (p->object.flags & SEEN)
 403                                 continue;
 404                         p->object.flags |= SEEN;
 405                         insert_by_date(p, list);
 406                 }
 407                 return 0;
 408         }
 409
 410         /*
 411          * Ok, the commit wasn't uninteresting. Try to
 412          * simplify the commit history and find the parent
 413          * that has no differences in the path set if one exists.
 414          */
 415         if (revs->prune_fn)
 416                 revs->prune_fn(revs, commit);
 417
 418         if (revs->no_walk)
 419                 return 0;
 420
 421         left_flag = (commit->object.flags & SYMMETRIC_LEFT);
 422
 423         rest = !revs->first_parent_only;
 424         for (parent = commit->parents, add = 1; parent; add = rest) {
 425                 struct commit *p = parent->item;
 426
 427                 parent = parent->next;
 428                 if (parse_commit(p) < 0)
 429                         return -1;
 430                 p->object.flags |= left_flag;
 431                 if (p->object.flags & SEEN)
 432                         continue;
 433                 p->object.flags |= SEEN;
 434                 if (add)
 435                         insert_by_date(p, list);
 436         }
 437         return 0;
 438 }
 439
 440 static void cherry_pick_list(struct commit_list *list)
 441 {
 442         struct commit_list *p;
 443         int left_count = 0, right_count = 0;
 444         int left_first;
 445         struct patch_ids ids;
 446
 447         /* First count the commits on the left and on the right */
 448         for (p = list; p; p = p->next) {
 449                 struct commit *commit = p->item;
 450                 unsigned flags = commit->object.flags;
 451                 if (flags & BOUNDARY)
 452                         ;
 453                 else if (flags & SYMMETRIC_LEFT)
 454                         left_count++;
 455                 else
 456                         right_count++;
 457         }
 458
 459         left_first = left_count < right_count;
 460         init_patch_ids(&ids);
 461
 462         /* Compute patch-ids for one side */
 463         for (p = list; p; p = p->next) {
 464                 struct commit *commit = p->item;
 465                 unsigned flags = commit->object.flags;
 466
 467                 if (flags & BOUNDARY)
 468                         continue;
 469                 /*
 470                  * If we have fewer left, left_first is set and we omit
 471                  * commits on the right branch in this loop.  If we have
 472                  * fewer right, we skip the left ones.
 473                  */
 474                 if (left_first != !!(flags & SYMMETRIC_LEFT))
 475                         continue;
 476                 commit->util = add_commit_patch_id(commit, &ids);
 477         }
 478
 479         /* Check the other side */
 480         for (p = list; p; p = p->next) {
 481                 struct commit *commit = p->item;
 482                 struct patch_id *id;
 483                 unsigned flags = commit->object.flags;
 484
 485                 if (flags & BOUNDARY)
 486                         continue;
 487                 /*
 488                  * If we have fewer left, left_first is set and we omit
 489                  * commits on the left branch in this loop.
 490                  */
 491                 if (left_first == !!(flags & SYMMETRIC_LEFT))
 492                         continue;
 493
 494                 /*
 495                  * Have we seen the same patch id?
 496                  */
 497                 id = has_commit_patch_id(commit, &ids);
 498                 if (!id)
 499                         continue;
 500                 id->seen = 1;
 501                 commit->object.flags |= SHOWN;
 502         }
 503
 504         /* Now check the original side for seen ones */
 505         for (p = list; p; p = p->next) {
 506                 struct commit *commit = p->item;
 507                 struct patch_id *ent;
 508
 509                 ent = commit->util;
 510                 if (!ent)
 511                         continue;
 512                 if (ent->seen)
 513                         commit->object.flags |= SHOWN;
 514                 commit->util = NULL;
 515         }
 516
 517         free_patch_ids(&ids);
 518 }
 519
 520 static int limit_list(struct rev_info *revs)
 521 {
 522         struct commit_list *list = revs->commits;
 523         struct commit_list *newlist = NULL;
 524         struct commit_list **p = &newlist;
 525
 526         while (list) {
 527                 struct commit_list *entry = list;
 528                 struct commit *commit = list->item;
 529                 struct object *obj = &commit->object;
 530
 531                 list = list->next;
 532                 free(entry);
 533
 534                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 535                         obj->flags |= UNINTERESTING;
 536                 if (add_parents_to_list(revs, commit, &list) < 0)
 537                         return -1;
 538                 if (obj->flags & UNINTERESTING) {
 539                         mark_parents_uninteresting(commit);
 540                         if (everybody_uninteresting(list))
 541                                 break;
 542                         continue;
 543                 }
 544                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 545                         continue;
 546                 p = &commit_list_insert(commit, p)->next;
 547         }
 548         if (revs->cherry_pick)
 549                 cherry_pick_list(newlist);
 550
 551         revs->commits = newlist;
 552         return 0;
 553 }
 554
 555 struct all_refs_cb {
 556         int all_flags;
 557         int warned_bad_reflog;
 558         struct rev_info *all_revs;
 559         const char *name_for_errormsg;
 560 };
 561
 562 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 563 {
 564         struct all_refs_cb *cb = cb_data;
 565         struct object *object = get_reference(cb->all_revs, path, sha1,
 566                                               cb->all_flags);
 567         add_pending_object(cb->all_revs, object, path);
 568         return 0;
 569 }
 570
 571 static void handle_all(struct rev_info *revs, unsigned flags)
 572 {
 573         struct all_refs_cb cb;
 574         cb.all_revs = revs;
 575         cb.all_flags = flags;
 576         for_each_ref(handle_one_ref, &cb);
 577 }
 578
 579 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 580 {
 581         struct all_refs_cb *cb = cb_data;
 582         if (!is_null_sha1(sha1)) {
 583                 struct object *o = parse_object(sha1);
 584                 if (o) {
 585                         o->flags |= cb->all_flags;
 586                         add_pending_object(cb->all_revs, o, "");
 587                 }
 588                 else if (!cb->warned_bad_reflog) {
 589                         warning("reflog of '%s' references pruned commits",
 590                                 cb->name_for_errormsg);
 591                         cb->warned_bad_reflog = 1;
 592                 }
 593         }
 594 }
 595
 596 static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 597                 const char *email, unsigned long timestamp, int tz,
 598                 const char *message, void *cb_data)
 599 {
 600         handle_one_reflog_commit(osha1, cb_data);
 601         handle_one_reflog_commit(nsha1, cb_data);
 602         return 0;
 603 }
 604
 605 static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 606 {
 607         struct all_refs_cb *cb = cb_data;
 608         cb->warned_bad_reflog = 0;
 609         cb->name_for_errormsg = path;
 610         for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
 611         return 0;
 612 }
 613
 614 static void handle_reflog(struct rev_info *revs, unsigned flags)
 615 {
 616         struct all_refs_cb cb;
 617         cb.all_revs = revs;
 618         cb.all_flags = flags;
 619         for_each_reflog(handle_one_reflog, &cb);
 620 }
 621
 622 static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 623 {
 624         unsigned char sha1[20];
 625         struct object *it;
 626         struct commit *commit;
 627         struct commit_list *parents;
 628
 629         if (*arg == '^') {
 630                 flags ^= UNINTERESTING;
 631                 arg++;
 632         }
 633         if (get_sha1(arg, sha1))
 634                 return 0;
 635         while (1) {
 636                 it = get_reference(revs, arg, sha1, 0);
 637                 if (it->type != OBJ_TAG)
 638                         break;
 639                 hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
 640         }
 641         if (it->type != OBJ_COMMIT)
 642                 return 0;
 643         commit = (struct commit *)it;
 644         for (parents = commit->parents; parents; parents = parents->next) {
 645                 it = &parents->item->object;
 646                 it->flags |= flags;
 647                 add_pending_object(revs, it, arg);
 648         }
 649         return 1;
 650 }
 651
 652 void init_revisions(struct rev_info *revs, const char *prefix)
 653 {
 654         memset(revs, 0, sizeof(*revs));
 655
 656         revs->abbrev = DEFAULT_ABBREV;
 657         revs->ignore_merges = 1;
 658         revs->simplify_history = 1;
 659         revs->pruning.recursive = 1;
 660         revs->pruning.quiet = 1;
 661         revs->pruning.add_remove = file_add_remove;
 662         revs->pruning.change = file_change;
 663         revs->lifo = 1;
 664         revs->dense = 1;
 665         revs->prefix = prefix;
 666         revs->max_age = -1;
 667         revs->min_age = -1;
 668         revs->skip_count = -1;
 669         revs->max_count = -1;
 670         revs->subject_prefix = "PATCH";
 671
 672         revs->prune_fn = NULL;
 673         revs->prune_data = NULL;
 674
 675         revs->topo_setter = topo_sort_default_setter;
 676         revs->topo_getter = topo_sort_default_getter;
 677
 678         revs->commit_format = CMIT_FMT_DEFAULT;
 679
 680         diff_setup(&revs->diffopt);
 681 }
 682
 683 static void add_pending_commit_list(struct rev_info *revs,
 684                                     struct commit_list *commit_list,
 685                                     unsigned int flags)
 686 {
 687         while (commit_list) {
 688                 struct object *object = &commit_list->item->object;
 689                 object->flags |= flags;
 690                 add_pending_object(revs, object, sha1_to_hex(object->sha1));
 691                 commit_list = commit_list->next;
 692         }
 693 }
 694
 695 static void prepare_show_merge(struct rev_info *revs)
 696 {
 697         struct commit_list *bases;
 698         struct commit *head, *other;
 699         unsigned char sha1[20];
 700         const char **prune = NULL;
 701         int i, prune_num = 1; /* counting terminating NULL */
 702
 703         if (get_sha1("HEAD", sha1) || !(head = lookup_commit(sha1)))
 704                 die("--merge without HEAD?");
 705         if (get_sha1("MERGE_HEAD", sha1) || !(other = lookup_commit(sha1)))
 706                 die("--merge without MERGE_HEAD?");
 707         add_pending_object(revs, &head->object, "HEAD");
 708         add_pending_object(revs, &other->object, "MERGE_HEAD");
 709         bases = get_merge_bases(head, other, 1);
 710         while (bases) {
 711                 struct commit *it = bases->item;
 712                 struct commit_list *n = bases->next;
 713                 free(bases);
 714                 bases = n;
 715                 it->object.flags |= UNINTERESTING;
 716                 add_pending_object(revs, &it->object, "(merge-base)");
 717         }
 718
 719         if (!active_nr)
 720                 read_cache();
 721         for (i = 0; i < active_nr; i++) {
 722                 struct cache_entry *ce = active_cache[i];
 723                 if (!ce_stage(ce))
 724                         continue;
 725                 if (ce_path_match(ce, revs->prune_data)) {
 726                         prune_num++;
 727                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
 728                         prune[prune_num-2] = ce->name;
 729                         prune[prune_num-1] = NULL;
 730                 }
 731                 while ((i+1 < active_nr) &&
 732                        ce_same_name(ce, active_cache[i+1]))
 733                         i++;
 734         }
 735         revs->prune_data = prune;
 736 }
 737
 738 int handle_revision_arg(const char *arg, struct rev_info *revs,
 739                         int flags,
 740                         int cant_be_filename)
 741 {
 742         unsigned mode;
 743         char *dotdot;
 744         struct object *object;
 745         unsigned char sha1[20];
 746         int local_flags;
 747
 748         dotdot = strstr(arg, "..");
 749         if (dotdot) {
 750                 unsigned char from_sha1[20];
 751                 const char *next = dotdot + 2;
 752                 const char *this = arg;
 753                 int symmetric = *next == '.';
 754                 unsigned int flags_exclude = flags ^ UNINTERESTING;
 755
 756                 *dotdot = 0;
 757                 next += symmetric;
 758
 759                 if (!*next)
 760                         next = "HEAD";
 761                 if (dotdot == arg)
 762                         this = "HEAD";
 763                 if (!get_sha1(this, from_sha1) &&
 764                     !get_sha1(next, sha1)) {
 765                         struct commit *a, *b;
 766                         struct commit_list *exclude;
 767
 768                         a = lookup_commit_reference(from_sha1);
 769                         b = lookup_commit_reference(sha1);
 770                         if (!a || !b) {
 771                                 die(symmetric ?
 772                                     "Invalid symmetric difference expression %s...%s" :
 773                                     "Invalid revision range %s..%s",
 774                                     arg, next);
 775                         }
 776
 777                         if (!cant_be_filename) {
 778                                 *dotdot = '.';
 779                                 verify_non_filename(revs->prefix, arg);
 780                         }
 781
 782                         if (symmetric) {
 783                                 exclude = get_merge_bases(a, b, 1);
 784                                 add_pending_commit_list(revs, exclude,
 785                                                         flags_exclude);
 786                                 free_commit_list(exclude);
 787                                 a->object.flags |= flags | SYMMETRIC_LEFT;
 788                         } else
 789                                 a->object.flags |= flags_exclude;
 790                         b->object.flags |= flags;
 791                         add_pending_object(revs, &a->object, this);
 792                         add_pending_object(revs, &b->object, next);
 793                         return 0;
 794                 }
 795                 *dotdot = '.';
 796         }
 797         dotdot = strstr(arg, "^@");
 798         if (dotdot && !dotdot[2]) {
 799                 *dotdot = 0;
 800                 if (add_parents_only(revs, arg, flags))
 801                         return 0;
 802                 *dotdot = '^';
 803         }
 804         dotdot = strstr(arg, "^!");
 805         if (dotdot && !dotdot[2]) {
 806                 *dotdot = 0;
 807                 if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
 808                         *dotdot = '^';
 809         }
 810
 811         local_flags = 0;
 812         if (*arg == '^') {
 813                 local_flags = UNINTERESTING;
 814                 arg++;
 815         }
 816         if (get_sha1_with_mode(arg, sha1, &mode))
 817                 return -1;
 818         if (!cant_be_filename)
 819                 verify_non_filename(revs->prefix, arg);
 820         object = get_reference(revs, arg, sha1, flags ^ local_flags);
 821         add_pending_object_with_mode(revs, object, arg, mode);
 822         return 0;
 823 }
 824
 825 static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
 826 {
 827         if (!revs->grep_filter) {
 828                 struct grep_opt *opt = xcalloc(1, sizeof(*opt));
 829                 opt->status_only = 1;
 830                 opt->pattern_tail = &(opt->pattern_list);
 831                 opt->regflags = REG_NEWLINE;
 832                 revs->grep_filter = opt;
 833         }
 834         append_grep_pattern(revs->grep_filter, ptn,
 835                             "command line", 0, what);
 836 }
 837
 838 static void add_header_grep(struct rev_info *revs, const char *field, const char *pattern)
 839 {
 840         char *pat;
 841         const char *prefix;
 842         int patlen, fldlen;
 843
 844         fldlen = strlen(field);
 845         patlen = strlen(pattern);
 846         pat = xmalloc(patlen + fldlen + 10);
 847         prefix = ".*";
 848         if (*pattern == '^') {
 849                 prefix = "";
 850                 pattern++;
 851         }
 852         sprintf(pat, "^%s %s%s", field, prefix, pattern);
 853         add_grep(revs, pat, GREP_PATTERN_HEAD);
 854 }
 855
 856 static void add_message_grep(struct rev_info *revs, const char *pattern)
 857 {
 858         add_grep(revs, pattern, GREP_PATTERN_BODY);
 859 }
 860
 861 static void add_ignore_packed(struct rev_info *revs, const char *name)
 862 {
 863         int num = ++revs->num_ignore_packed;
 864
 865         revs->ignore_packed = xrealloc(revs->ignore_packed,
 866                                        sizeof(const char **) * (num + 1));
 867         revs->ignore_packed[num-1] = name;
 868         revs->ignore_packed[num] = NULL;
 869 }
 870
 871 /*
 872  * Parse revision information, filling in the "rev_info" structure,
 873  * and removing the used arguments from the argument list.
 874  *
 875  * Returns the number of arguments left that weren't recognized
 876  * (which are also moved to the head of the argument list)
 877  */
 878 int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
 879 {
 880         int i, flags, seen_dashdash, show_merge;
 881         const char **unrecognized = argv + 1;
 882         int left = 1;
 883         int all_match = 0;
 884
 885         /* First, search for "--" */
 886         seen_dashdash = 0;
 887         for (i = 1; i < argc; i++) {
 888                 const char *arg = argv[i];
 889                 if (strcmp(arg, "--"))
 890                         continue;
 891                 argv[i] = NULL;
 892                 argc = i;
 893                 revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
 894                 seen_dashdash = 1;
 895                 break;
 896         }
 897
 898         flags = show_merge = 0;
 899         for (i = 1; i < argc; i++) {
 900                 const char *arg = argv[i];
 901                 if (*arg == '-') {
 902                         int opts;
 903                         if (!prefixcmp(arg, "--max-count=")) {
 904                                 revs->max_count = atoi(arg + 12);
 905                                 continue;
 906                         }
 907                         if (!prefixcmp(arg, "--skip=")) {
 908                                 revs->skip_count = atoi(arg + 7);
 909                                 continue;
 910                         }
 911                         /* accept -<digit>, like traditional "head" */
 912                         if ((*arg == '-') && isdigit(arg[1])) {
 913                                 revs->max_count = atoi(arg + 1);
 914                                 continue;
 915                         }
 916                         if (!strcmp(arg, "-n")) {
 917                                 if (argc <= i + 1)
 918                                         die("-n requires an argument");
 919                                 revs->max_count = atoi(argv[++i]);
 920                                 continue;
 921                         }
 922                         if (!prefixcmp(arg, "-n")) {
 923                                 revs->max_count = atoi(arg + 2);
 924                                 continue;
 925                         }
 926                         if (!prefixcmp(arg, "--max-age=")) {
 927                                 revs->max_age = atoi(arg + 10);
 928                                 continue;
 929                         }
 930                         if (!prefixcmp(arg, "--since=")) {
 931                                 revs->max_age = approxidate(arg + 8);
 932                                 continue;
 933                         }
 934                         if (!prefixcmp(arg, "--after=")) {
 935                                 revs->max_age = approxidate(arg + 8);
 936                                 continue;
 937                         }
 938                         if (!prefixcmp(arg, "--min-age=")) {
 939                                 revs->min_age = atoi(arg + 10);
 940                                 continue;
 941                         }
 942                         if (!prefixcmp(arg, "--before=")) {
 943                                 revs->min_age = approxidate(arg + 9);
 944                                 continue;
 945                         }
 946                         if (!prefixcmp(arg, "--until=")) {
 947                                 revs->min_age = approxidate(arg + 8);
 948                                 continue;
 949                         }
 950                         if (!strcmp(arg, "--all")) {
 951                                 handle_all(revs, flags);
 952                                 continue;
 953                         }
 954                         if (!strcmp(arg, "--first-parent")) {
 955                                 revs->first_parent_only = 1;
 956                                 continue;
 957                         }
 958                         if (!strcmp(arg, "--reflog")) {
 959                                 handle_reflog(revs, flags);
 960                                 continue;
 961                         }
 962                         if (!strcmp(arg, "-g") ||
 963                                         !strcmp(arg, "--walk-reflogs")) {
 964                                 init_reflog_walk(&revs->reflog_info);
 965                                 continue;
 966                         }
 967                         if (!strcmp(arg, "--not")) {
 968                                 flags ^= UNINTERESTING;
 969                                 continue;
 970                         }
 971                         if (!strcmp(arg, "--default")) {
 972                                 if (++i >= argc)
 973                                         die("bad --default argument");
 974                                 def = argv[i];
 975                                 continue;
 976                         }
 977                         if (!strcmp(arg, "--merge")) {
 978                                 show_merge = 1;
 979                                 continue;
 980                         }
 981                         if (!strcmp(arg, "--topo-order")) {
 982                                 revs->topo_order = 1;
 983                                 continue;
 984                         }
 985                         if (!strcmp(arg, "--date-order")) {
 986                                 revs->lifo = 0;
 987                                 revs->topo_order = 1;
 988                                 continue;
 989                         }
 990                         if (!strcmp(arg, "--parents")) {
 991                                 revs->parents = 1;
 992                                 continue;
 993                         }
 994                         if (!strcmp(arg, "--dense")) {
 995                                 revs->dense = 1;
 996                                 continue;
 997                         }
 998                         if (!strcmp(arg, "--sparse")) {
 999                                 revs->dense = 0;
1000                                 continue;
1001                         }
1002                         if (!strcmp(arg, "--remove-empty")) {
1003                                 revs->remove_empty_trees = 1;
1004                                 continue;
1005                         }
1006                         if (!strcmp(arg, "--no-merges")) {
1007                                 revs->no_merges = 1;
1008                                 continue;
1009                         }
1010                         if (!strcmp(arg, "--boundary")) {
1011                                 revs->boundary = 1;
1012                                 continue;
1013                         }
1014                         if (!strcmp(arg, "--left-right")) {
1015                                 revs->left_right = 1;
1016                                 continue;
1017                         }
1018                         if (!strcmp(arg, "--cherry-pick")) {
1019                                 revs->cherry_pick = 1;
1020                                 continue;
1021                         }
1022                         if (!strcmp(arg, "--objects")) {
1023                                 revs->tag_objects = 1;
1024                                 revs->tree_objects = 1;
1025                                 revs->blob_objects = 1;
1026                                 continue;
1027                         }
1028                         if (!strcmp(arg, "--objects-edge")) {
1029                                 revs->tag_objects = 1;
1030                                 revs->tree_objects = 1;
1031                                 revs->blob_objects = 1;
1032                                 revs->edge_hint = 1;
1033                                 continue;
1034                         }
1035                         if (!strcmp(arg, "--unpacked")) {
1036                                 revs->unpacked = 1;
1037                                 free(revs->ignore_packed);
1038                                 revs->ignore_packed = NULL;
1039                                 revs->num_ignore_packed = 0;
1040                                 continue;
1041                         }
1042                         if (!prefixcmp(arg, "--unpacked=")) {
1043                                 revs->unpacked = 1;
1044                                 add_ignore_packed(revs, arg+11);
1045                                 continue;
1046                         }
1047                         if (!strcmp(arg, "-r")) {
1048                                 revs->diff = 1;
1049                                 revs->diffopt.recursive = 1;
1050                                 continue;
1051                         }
1052                         if (!strcmp(arg, "-t")) {
1053                                 revs->diff = 1;
1054                                 revs->diffopt.recursive = 1;
1055                                 revs->diffopt.tree_in_recursive = 1;
1056                                 continue;
1057                         }
1058                         if (!strcmp(arg, "-m")) {
1059                                 revs->ignore_merges = 0;
1060                                 continue;
1061                         }
1062                         if (!strcmp(arg, "-c")) {
1063                                 revs->diff = 1;
1064                                 revs->dense_combined_merges = 0;
1065                                 revs->combine_merges = 1;
1066                                 continue;
1067                         }
1068                         if (!strcmp(arg, "--cc")) {
1069                                 revs->diff = 1;
1070                                 revs->dense_combined_merges = 1;
1071                                 revs->combine_merges = 1;
1072                                 continue;
1073                         }
1074                         if (!strcmp(arg, "-v")) {
1075                                 revs->verbose_header = 1;
1076                                 continue;
1077                         }
1078                         if (!prefixcmp(arg, "--pretty")) {
1079                                 revs->verbose_header = 1;
1080                                 revs->commit_format = get_commit_format(arg+8);
1081                                 continue;
1082                         }
1083                         if (!strcmp(arg, "--root")) {
1084                                 revs->show_root_diff = 1;
1085                                 continue;
1086                         }
1087                         if (!strcmp(arg, "--no-commit-id")) {
1088                                 revs->no_commit_id = 1;
1089                                 continue;
1090                         }
1091                         if (!strcmp(arg, "--always")) {
1092                                 revs->always_show_header = 1;
1093                                 continue;
1094                         }
1095                         if (!strcmp(arg, "--no-abbrev")) {
1096                                 revs->abbrev = 0;
1097                                 continue;
1098                         }
1099                         if (!strcmp(arg, "--abbrev")) {
1100                                 revs->abbrev = DEFAULT_ABBREV;
1101                                 continue;
1102                         }
1103                         if (!prefixcmp(arg, "--abbrev=")) {
1104                                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1105                                 if (revs->abbrev < MINIMUM_ABBREV)
1106                                         revs->abbrev = MINIMUM_ABBREV;
1107                                 else if (revs->abbrev > 40)
1108                                         revs->abbrev = 40;
1109                                 continue;
1110                         }
1111                         if (!strcmp(arg, "--abbrev-commit")) {
1112                                 revs->abbrev_commit = 1;
1113                                 continue;
1114                         }
1115                         if (!strcmp(arg, "--full-diff")) {
1116                                 revs->diff = 1;
1117                                 revs->full_diff = 1;
1118                                 continue;
1119                         }
1120                         if (!strcmp(arg, "--full-history")) {
1121                                 revs->simplify_history = 0;
1122                                 continue;
1123                         }
1124                         if (!strcmp(arg, "--relative-date")) {
1125                                 revs->date_mode = DATE_RELATIVE;
1126                                 continue;
1127                         }
1128                         if (!strncmp(arg, "--date=", 7)) {
1129                                 if (!strcmp(arg + 7, "relative"))
1130                                         revs->date_mode = DATE_RELATIVE;
1131                                 else if (!strcmp(arg + 7, "local"))
1132                                         revs->date_mode = DATE_LOCAL;
1133                                 else if (!strcmp(arg + 7, "default"))
1134                                         revs->date_mode = DATE_NORMAL;
1135                                 else
1136                                         die("unknown date format %s", arg);
1137                                 continue;
1138                         }
1139
1140                         /*
1141                          * Grepping the commit log
1142                          */
1143                         if (!prefixcmp(arg, "--author=")) {
1144                                 add_header_grep(revs, "author", arg+9);
1145                                 continue;
1146                         }
1147                         if (!prefixcmp(arg, "--committer=")) {
1148                                 add_header_grep(revs, "committer", arg+12);
1149                                 continue;
1150                         }
1151                         if (!prefixcmp(arg, "--grep=")) {
1152                                 add_message_grep(revs, arg+7);
1153                                 continue;
1154                         }
1155                         if (!strcmp(arg, "--all-match")) {
1156                                 all_match = 1;
1157                                 continue;
1158                         }
1159                         if (!prefixcmp(arg, "--encoding=")) {
1160                                 arg += 11;
1161                                 if (strcmp(arg, "none"))
1162                                         git_log_output_encoding = xstrdup(arg);
1163                                 else
1164                                         git_log_output_encoding = "";
1165                                 continue;
1166                         }
1167                         if (!strcmp(arg, "--reverse")) {
1168                                 revs->reverse ^= 1;
1169                                 continue;
1170                         }
1171
1172                         opts = diff_opt_parse(&revs->diffopt, argv+i, argc-i);
1173                         if (opts > 0) {
1174                                 if (strcmp(argv[i], "-z"))
1175                                         revs->diff = 1;
1176                                 i += opts - 1;
1177                                 continue;
1178                         }
1179                         *unrecognized++ = arg;
1180                         left++;
1181                         continue;
1182                 }
1183
1184                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1185                         int j;
1186                         if (seen_dashdash || *arg == '^')
1187                                 die("bad revision '%s'", arg);
1188
1189                         /* If we didn't have a "--":
1190                          * (1) all filenames must exist;
1191                          * (2) all rev-args must not be interpretable
1192                          *     as a valid filename.
1193                          * but the latter we have checked in the main loop.
1194                          */
1195                         for (j = i; j < argc; j++)
1196                                 verify_filename(revs->prefix, argv[j]);
1197
1198                         revs->prune_data = get_pathspec(revs->prefix,
1199                                                         argv + i);
1200                         break;
1201                 }
1202         }
1203
1204         if (show_merge)
1205                 prepare_show_merge(revs);
1206         if (def && !revs->pending.nr) {
1207                 unsigned char sha1[20];
1208                 struct object *object;
1209                 unsigned mode;
1210                 if (get_sha1_with_mode(def, sha1, &mode))
1211                         die("bad default revision '%s'", def);
1212                 object = get_reference(revs, def, sha1, 0);
1213                 add_pending_object_with_mode(revs, object, def, mode);
1214         }
1215
1216         if (revs->topo_order)
1217                 revs->limited = 1;
1218
1219         if (revs->prune_data) {
1220                 diff_tree_setup_paths(revs->prune_data, &revs->pruning);
1221                 revs->prune_fn = try_to_simplify_commit;
1222                 if (!revs->full_diff)
1223                         diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
1224         }
1225         if (revs->combine_merges) {
1226                 revs->ignore_merges = 0;
1227                 if (revs->dense_combined_merges && !revs->diffopt.output_format)
1228                         revs->diffopt.output_format = DIFF_FORMAT_PATCH;
1229         }
1230         revs->diffopt.abbrev = revs->abbrev;
1231         if (diff_setup_done(&revs->diffopt) < 0)
1232                 die("diff_setup_done failed");
1233
1234         if (revs->grep_filter) {
1235                 revs->grep_filter->all_match = all_match;
1236                 compile_grep_patterns(revs->grep_filter);
1237         }
1238
1239         return left;
1240 }
1241
1242 int prepare_revision_walk(struct rev_info *revs)
1243 {
1244         int nr = revs->pending.nr;
1245         struct object_array_entry *e, *list;
1246
1247         e = list = revs->pending.objects;
1248         revs->pending.nr = 0;
1249         revs->pending.alloc = 0;
1250         revs->pending.objects = NULL;
1251         while (--nr >= 0) {
1252                 struct commit *commit = handle_commit(revs, e->item, e->name);
1253                 if (commit) {
1254                         if (!(commit->object.flags & SEEN)) {
1255                                 commit->object.flags |= SEEN;
1256                                 insert_by_date(commit, &revs->commits);
1257                         }
1258                 }
1259                 e++;
1260         }
1261         free(list);
1262
1263         if (revs->no_walk)
1264                 return 0;
1265         if (revs->limited)
1266                 if (limit_list(revs) < 0)
1267                         return -1;
1268         if (revs->topo_order)
1269                 sort_in_topological_order_fn(&revs->commits, revs->lifo,
1270                                              revs->topo_setter,
1271                                              revs->topo_getter);
1272         return 0;
1273 }
1274
1275 enum rewrite_result {
1276         rewrite_one_ok,
1277         rewrite_one_noparents,
1278         rewrite_one_error,
1279 };
1280
1281 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
1282 {
1283         for (;;) {
1284                 struct commit *p = *pp;
1285                 if (!revs->limited)
1286                         if (add_parents_to_list(revs, p, &revs->commits) < 0)
1287                                 return rewrite_one_error;
1288                 if (p->parents && p->parents->next)
1289                         return rewrite_one_ok;
1290                 if (p->object.flags & (TREECHANGE | UNINTERESTING))
1291                         return rewrite_one_ok;
1292                 if (!p->parents)
1293                         return rewrite_one_noparents;
1294                 *pp = p->parents->item;
1295         }
1296 }
1297
1298 static int rewrite_parents(struct rev_info *revs, struct commit *commit)
1299 {
1300         struct commit_list **pp = &commit->parents;
1301         while (*pp) {
1302                 struct commit_list *parent = *pp;
1303                 switch (rewrite_one(revs, &parent->item)) {
1304                 case rewrite_one_ok:
1305                         break;
1306                 case rewrite_one_noparents:
1307                         *pp = parent->next;
1308                         continue;
1309                 case rewrite_one_error:
1310                         return -1;
1311                 }
1312                 pp = &parent->next;
1313         }
1314         return 0;
1315 }
1316
1317 static int commit_match(struct commit *commit, struct rev_info *opt)
1318 {
1319         if (!opt->grep_filter)
1320                 return 1;
1321         return grep_buffer(opt->grep_filter,
1322                            NULL, /* we say nothing, not even filename */
1323                            commit->buffer, strlen(commit->buffer));
1324 }
1325
1326 static struct commit *get_revision_1(struct rev_info *revs)
1327 {
1328         if (!revs->commits)
1329                 return NULL;
1330
1331         do {
1332                 struct commit_list *entry = revs->commits;
1333                 struct commit *commit = entry->item;
1334
1335                 revs->commits = entry->next;
1336                 free(entry);
1337
1338                 if (revs->reflog_info)
1339                         fake_reflog_parent(revs->reflog_info, commit);
1340
1341                 /*
1342                  * If we haven't done the list limiting, we need to look at
1343                  * the parents here. We also need to do the date-based limiting
1344                  * that we'd otherwise have done in limit_list().
1345                  */
1346                 if (!revs->limited) {
1347                         if (revs->max_age != -1 &&
1348                             (commit->date < revs->max_age))
1349                                 continue;
1350                         if (add_parents_to_list(revs, commit, &revs->commits) < 0)
1351                                 return NULL;
1352                 }
1353                 if (commit->object.flags & SHOWN)
1354                         continue;
1355
1356                 if (revs->unpacked && has_sha1_pack(commit->object.sha1,
1357                                                     revs->ignore_packed))
1358                     continue;
1359
1360                 if (commit->object.flags & UNINTERESTING)
1361                         continue;
1362                 if (revs->min_age != -1 && (commit->date > revs->min_age))
1363                         continue;
1364                 if (revs->no_merges &&
1365                     commit->parents && commit->parents->next)
1366                         continue;
1367                 if (!commit_match(commit, revs))
1368                         continue;
1369                 if (revs->prune_fn && revs->dense) {
1370                         /* Commit without changes? */
1371                         if (!(commit->object.flags & TREECHANGE)) {
1372                                 /* drop merges unless we want parenthood */
1373                                 if (!revs->parents)
1374                                         continue;
1375                                 /* non-merge - always ignore it */
1376                                 if (!commit->parents || !commit->parents->next)
1377                                         continue;
1378                         }
1379                         if (revs->parents && rewrite_parents(revs, commit) < 0)
1380                                 return NULL;
1381                 }
1382                 return commit;
1383         } while (revs->commits);
1384         return NULL;
1385 }
1386
1387 static void gc_boundary(struct object_array *array)
1388 {
1389         unsigned nr = array->nr;
1390         unsigned alloc = array->alloc;
1391         struct object_array_entry *objects = array->objects;
1392
1393         if (alloc <= nr) {
1394                 unsigned i, j;
1395                 for (i = j = 0; i < nr; i++) {
1396                         if (objects[i].item->flags & SHOWN)
1397                                 continue;
1398                         if (i != j)
1399                                 objects[j] = objects[i];
1400                         j++;
1401                 }
1402                 for (i = j; i < nr; i++)
1403                         objects[i].item = NULL;
1404                 array->nr = j;
1405         }
1406 }
1407
1408 struct commit *get_revision(struct rev_info *revs)
1409 {
1410         struct commit *c = NULL;
1411         struct commit_list *l;
1412
1413         if (revs->boundary == 2) {
1414                 unsigned i;
1415                 struct object_array *array = &revs->boundary_commits;
1416                 struct object_array_entry *objects = array->objects;
1417                 for (i = 0; i < array->nr; i++) {
1418                         c = (struct commit *)(objects[i].item);
1419                         if (!c)
1420                                 continue;
1421                         if (!(c->object.flags & CHILD_SHOWN))
1422                                 continue;
1423                         if (!(c->object.flags & SHOWN))
1424                                 break;
1425                 }
1426                 if (array->nr <= i)
1427                         return NULL;
1428
1429                 c->object.flags |= SHOWN | BOUNDARY;
1430                 return c;
1431         }
1432
1433         if (revs->reverse) {
1434                 int limit = -1;
1435
1436                 if (0 <= revs->max_count) {
1437                         limit = revs->max_count;
1438                         if (0 < revs->skip_count)
1439                                 limit += revs->skip_count;
1440                 }
1441                 l = NULL;
1442                 while ((c = get_revision_1(revs))) {
1443                         commit_list_insert(c, &l);
1444                         if ((0 < limit) && !--limit)
1445                                 break;
1446                 }
1447                 revs->commits = l;
1448                 revs->reverse = 0;
1449                 revs->max_count = -1;
1450                 c = NULL;
1451         }
1452
1453         /*
1454          * Now pick up what they want to give us
1455          */
1456         c = get_revision_1(revs);
1457         if (c) {
1458                 while (0 < revs->skip_count) {
1459                         revs->skip_count--;
1460                         c = get_revision_1(revs);
1461                         if (!c)
1462                                 break;
1463                 }
1464         }
1465
1466         /*
1467          * Check the max_count.
1468          */
1469         switch (revs->max_count) {
1470         case -1:
1471                 break;
1472         case 0:
1473                 c = NULL;
1474                 break;
1475         default:
1476                 revs->max_count--;
1477         }
1478
1479         if (c)
1480                 c->object.flags |= SHOWN;
1481
1482         if (!revs->boundary) {
1483                 return c;
1484         }
1485
1486         if (!c) {
1487                 /*
1488                  * get_revision_1() runs out the commits, and
1489                  * we are done computing the boundaries.
1490                  * switch to boundary commits output mode.
1491                  */
1492                 revs->boundary = 2;
1493                 return get_revision(revs);
1494         }
1495
1496         /*
1497          * boundary commits are the commits that are parents of the
1498          * ones we got from get_revision_1() but they themselves are
1499          * not returned from get_revision_1().  Before returning
1500          * 'c', we need to mark its parents that they could be boundaries.
1501          */
1502
1503         for (l = c->parents; l; l = l->next) {
1504                 struct object *p;
1505                 p = &(l->item->object);
1506                 if (p->flags & (CHILD_SHOWN | SHOWN))
1507                         continue;
1508                 p->flags |= CHILD_SHOWN;
1509                 gc_boundary(&revs->boundary_commits);
1510                 add_object_array(p, NULL, &revs->boundary_commits);
1511         }
1512
1513         return c;
1514 }