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 static void add_pending_object_with_mode(struct rev_info *revs, struct object *obj, const char *name, unsigned mode)
 118 {
 119         if (revs->no_walk && (obj->flags & UNINTERESTING))
 120                 die("object ranges do not make sense when not walking revisions");
 121         add_object_array_with_mode(obj, name, &revs->pending, mode);
 122         if (revs->reflog_info && obj->type == OBJ_COMMIT)
 123                 add_reflog_for_walk(revs->reflog_info,
 124                                 (struct commit *)obj, name);
 125 }
 126
 127 void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
 128 {
 129         add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
 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 static 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 static 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         int regflags = 0;
 885
 886         /* First, search for "--" */
 887         seen_dashdash = 0;
 888         for (i = 1; i < argc; i++) {
 889                 const char *arg = argv[i];
 890                 if (strcmp(arg, "--"))
 891                         continue;
 892                 argv[i] = NULL;
 893                 argc = i;
 894                 revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
 895                 seen_dashdash = 1;
 896                 break;
 897         }
 898
 899         flags = show_merge = 0;
 900         for (i = 1; i < argc; i++) {
 901                 const char *arg = argv[i];
 902                 if (*arg == '-') {
 903                         int opts;
 904                         if (!prefixcmp(arg, "--max-count=")) {
 905                                 revs->max_count = atoi(arg + 12);
 906                                 continue;
 907                         }
 908                         if (!prefixcmp(arg, "--skip=")) {
 909                                 revs->skip_count = atoi(arg + 7);
 910                                 continue;
 911                         }
 912                         /* accept -<digit>, like traditional "head" */
 913                         if ((*arg == '-') && isdigit(arg[1])) {
 914                                 revs->max_count = atoi(arg + 1);
 915                                 continue;
 916                         }
 917                         if (!strcmp(arg, "-n")) {
 918                                 if (argc <= i + 1)
 919                                         die("-n requires an argument");
 920                                 revs->max_count = atoi(argv[++i]);
 921                                 continue;
 922                         }
 923                         if (!prefixcmp(arg, "-n")) {
 924                                 revs->max_count = atoi(arg + 2);
 925                                 continue;
 926                         }
 927                         if (!prefixcmp(arg, "--max-age=")) {
 928                                 revs->max_age = atoi(arg + 10);
 929                                 continue;
 930                         }
 931                         if (!prefixcmp(arg, "--since=")) {
 932                                 revs->max_age = approxidate(arg + 8);
 933                                 continue;
 934                         }
 935                         if (!prefixcmp(arg, "--after=")) {
 936                                 revs->max_age = approxidate(arg + 8);
 937                                 continue;
 938                         }
 939                         if (!prefixcmp(arg, "--min-age=")) {
 940                                 revs->min_age = atoi(arg + 10);
 941                                 continue;
 942                         }
 943                         if (!prefixcmp(arg, "--before=")) {
 944                                 revs->min_age = approxidate(arg + 9);
 945                                 continue;
 946                         }
 947                         if (!prefixcmp(arg, "--until=")) {
 948                                 revs->min_age = approxidate(arg + 8);
 949                                 continue;
 950                         }
 951                         if (!strcmp(arg, "--all")) {
 952                                 handle_all(revs, flags);
 953                                 continue;
 954                         }
 955                         if (!strcmp(arg, "--first-parent")) {
 956                                 revs->first_parent_only = 1;
 957                                 continue;
 958                         }
 959                         if (!strcmp(arg, "--reflog")) {
 960                                 handle_reflog(revs, flags);
 961                                 continue;
 962                         }
 963                         if (!strcmp(arg, "-g") ||
 964                                         !strcmp(arg, "--walk-reflogs")) {
 965                                 init_reflog_walk(&revs->reflog_info);
 966                                 continue;
 967                         }
 968                         if (!strcmp(arg, "--not")) {
 969                                 flags ^= UNINTERESTING;
 970                                 continue;
 971                         }
 972                         if (!strcmp(arg, "--default")) {
 973                                 if (++i >= argc)
 974                                         die("bad --default argument");
 975                                 def = argv[i];
 976                                 continue;
 977                         }
 978                         if (!strcmp(arg, "--merge")) {
 979                                 show_merge = 1;
 980                                 continue;
 981                         }
 982                         if (!strcmp(arg, "--topo-order")) {
 983                                 revs->topo_order = 1;
 984                                 continue;
 985                         }
 986                         if (!strcmp(arg, "--date-order")) {
 987                                 revs->lifo = 0;
 988                                 revs->topo_order = 1;
 989                                 continue;
 990                         }
 991                         if (!strcmp(arg, "--parents")) {
 992                                 revs->parents = 1;
 993                                 continue;
 994                         }
 995                         if (!strcmp(arg, "--dense")) {
 996                                 revs->dense = 1;
 997                                 continue;
 998                         }
 999                         if (!strcmp(arg, "--sparse")) {
1000                                 revs->dense = 0;
1001                                 continue;
1002                         }
1003                         if (!strcmp(arg, "--remove-empty")) {
1004                                 revs->remove_empty_trees = 1;
1005                                 continue;
1006                         }
1007                         if (!strcmp(arg, "--no-merges")) {
1008                                 revs->no_merges = 1;
1009                                 continue;
1010                         }
1011                         if (!strcmp(arg, "--boundary")) {
1012                                 revs->boundary = 1;
1013                                 continue;
1014                         }
1015                         if (!strcmp(arg, "--left-right")) {
1016                                 revs->left_right = 1;
1017                                 continue;
1018                         }
1019                         if (!strcmp(arg, "--cherry-pick")) {
1020                                 revs->cherry_pick = 1;
1021                                 continue;
1022                         }
1023                         if (!strcmp(arg, "--objects")) {
1024                                 revs->tag_objects = 1;
1025                                 revs->tree_objects = 1;
1026                                 revs->blob_objects = 1;
1027                                 continue;
1028                         }
1029                         if (!strcmp(arg, "--objects-edge")) {
1030                                 revs->tag_objects = 1;
1031                                 revs->tree_objects = 1;
1032                                 revs->blob_objects = 1;
1033                                 revs->edge_hint = 1;
1034                                 continue;
1035                         }
1036                         if (!strcmp(arg, "--unpacked")) {
1037                                 revs->unpacked = 1;
1038                                 free(revs->ignore_packed);
1039                                 revs->ignore_packed = NULL;
1040                                 revs->num_ignore_packed = 0;
1041                                 continue;
1042                         }
1043                         if (!prefixcmp(arg, "--unpacked=")) {
1044                                 revs->unpacked = 1;
1045                                 add_ignore_packed(revs, arg+11);
1046                                 continue;
1047                         }
1048                         if (!strcmp(arg, "-r")) {
1049                                 revs->diff = 1;
1050                                 revs->diffopt.recursive = 1;
1051                                 continue;
1052                         }
1053                         if (!strcmp(arg, "-t")) {
1054                                 revs->diff = 1;
1055                                 revs->diffopt.recursive = 1;
1056                                 revs->diffopt.tree_in_recursive = 1;
1057                                 continue;
1058                         }
1059                         if (!strcmp(arg, "-m")) {
1060                                 revs->ignore_merges = 0;
1061                                 continue;
1062                         }
1063                         if (!strcmp(arg, "-c")) {
1064                                 revs->diff = 1;
1065                                 revs->dense_combined_merges = 0;
1066                                 revs->combine_merges = 1;
1067                                 continue;
1068                         }
1069                         if (!strcmp(arg, "--cc")) {
1070                                 revs->diff = 1;
1071                                 revs->dense_combined_merges = 1;
1072                                 revs->combine_merges = 1;
1073                                 continue;
1074                         }
1075                         if (!strcmp(arg, "-v")) {
1076                                 revs->verbose_header = 1;
1077                                 continue;
1078                         }
1079                         if (!prefixcmp(arg, "--pretty")) {
1080                                 revs->verbose_header = 1;
1081                                 revs->commit_format = get_commit_format(arg+8);
1082                                 continue;
1083                         }
1084                         if (!strcmp(arg, "--root")) {
1085                                 revs->show_root_diff = 1;
1086                                 continue;
1087                         }
1088                         if (!strcmp(arg, "--no-commit-id")) {
1089                                 revs->no_commit_id = 1;
1090                                 continue;
1091                         }
1092                         if (!strcmp(arg, "--always")) {
1093                                 revs->always_show_header = 1;
1094                                 continue;
1095                         }
1096                         if (!strcmp(arg, "--no-abbrev")) {
1097                                 revs->abbrev = 0;
1098                                 continue;
1099                         }
1100                         if (!strcmp(arg, "--abbrev")) {
1101                                 revs->abbrev = DEFAULT_ABBREV;
1102                                 continue;
1103                         }
1104                         if (!prefixcmp(arg, "--abbrev=")) {
1105                                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1106                                 if (revs->abbrev < MINIMUM_ABBREV)
1107                                         revs->abbrev = MINIMUM_ABBREV;
1108                                 else if (revs->abbrev > 40)
1109                                         revs->abbrev = 40;
1110                                 continue;
1111                         }
1112                         if (!strcmp(arg, "--abbrev-commit")) {
1113                                 revs->abbrev_commit = 1;
1114                                 continue;
1115                         }
1116                         if (!strcmp(arg, "--full-diff")) {
1117                                 revs->diff = 1;
1118                                 revs->full_diff = 1;
1119                                 continue;
1120                         }
1121                         if (!strcmp(arg, "--full-history")) {
1122                                 revs->simplify_history = 0;
1123                                 continue;
1124                         }
1125                         if (!strcmp(arg, "--relative-date")) {
1126                                 revs->date_mode = DATE_RELATIVE;
1127                                 continue;
1128                         }
1129                         if (!strncmp(arg, "--date=", 7)) {
1130                                 if (!strcmp(arg + 7, "relative"))
1131                                         revs->date_mode = DATE_RELATIVE;
1132                                 else if (!strcmp(arg + 7, "local"))
1133                                         revs->date_mode = DATE_LOCAL;
1134                                 else if (!strcmp(arg + 7, "default"))
1135                                         revs->date_mode = DATE_NORMAL;
1136                                 else
1137                                         die("unknown date format %s", arg);
1138                                 continue;
1139                         }
1140
1141                         /*
1142                          * Grepping the commit log
1143                          */
1144                         if (!prefixcmp(arg, "--author=")) {
1145                                 add_header_grep(revs, "author", arg+9);
1146                                 continue;
1147                         }
1148                         if (!prefixcmp(arg, "--committer=")) {
1149                                 add_header_grep(revs, "committer", arg+12);
1150                                 continue;
1151                         }
1152                         if (!prefixcmp(arg, "--grep=")) {
1153                                 add_message_grep(revs, arg+7);
1154                                 continue;
1155                         }
1156                         if (!prefixcmp(arg, "--extended-regexp")) {
1157                                 regflags |= REG_EXTENDED;
1158                                 continue;
1159                         }
1160                         if (!prefixcmp(arg, "--regexp-ignore-case")) {
1161                                 regflags |= REG_ICASE;
1162                                 continue;
1163                         }
1164                         if (!strcmp(arg, "--all-match")) {
1165                                 all_match = 1;
1166                                 continue;
1167                         }
1168                         if (!prefixcmp(arg, "--encoding=")) {
1169                                 arg += 11;
1170                                 if (strcmp(arg, "none"))
1171                                         git_log_output_encoding = xstrdup(arg);
1172                                 else
1173                                         git_log_output_encoding = "";
1174                                 continue;
1175                         }
1176                         if (!strcmp(arg, "--reverse")) {
1177                                 revs->reverse ^= 1;
1178                                 continue;
1179                         }
1180
1181                         opts = diff_opt_parse(&revs->diffopt, argv+i, argc-i);
1182                         if (opts > 0) {
1183                                 if (strcmp(argv[i], "-z"))
1184                                         revs->diff = 1;
1185                                 i += opts - 1;
1186                                 continue;
1187                         }
1188                         *unrecognized++ = arg;
1189                         left++;
1190                         continue;
1191                 }
1192
1193                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1194                         int j;
1195                         if (seen_dashdash || *arg == '^')
1196                                 die("bad revision '%s'", arg);
1197
1198                         /* If we didn't have a "--":
1199                          * (1) all filenames must exist;
1200                          * (2) all rev-args must not be interpretable
1201                          *     as a valid filename.
1202                          * but the latter we have checked in the main loop.
1203                          */
1204                         for (j = i; j < argc; j++)
1205                                 verify_filename(revs->prefix, argv[j]);
1206
1207                         revs->prune_data = get_pathspec(revs->prefix,
1208                                                         argv + i);
1209                         break;
1210                 }
1211         }
1212
1213         if (revs->grep_filter)
1214                 revs->grep_filter->regflags |= regflags;
1215
1216         if (show_merge)
1217                 prepare_show_merge(revs);
1218         if (def && !revs->pending.nr) {
1219                 unsigned char sha1[20];
1220                 struct object *object;
1221                 unsigned mode;
1222                 if (get_sha1_with_mode(def, sha1, &mode))
1223                         die("bad default revision '%s'", def);
1224                 object = get_reference(revs, def, sha1, 0);
1225                 add_pending_object_with_mode(revs, object, def, mode);
1226         }
1227
1228         if (revs->topo_order)
1229                 revs->limited = 1;
1230
1231         if (revs->prune_data) {
1232                 diff_tree_setup_paths(revs->prune_data, &revs->pruning);
1233                 /* Can't prune commits with rename following: the paths change.. */
1234                 if (!revs->diffopt.follow_renames)
1235                         revs->prune_fn = try_to_simplify_commit;
1236                 if (!revs->full_diff)
1237                         diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
1238         }
1239         if (revs->combine_merges) {
1240                 revs->ignore_merges = 0;
1241                 if (revs->dense_combined_merges && !revs->diffopt.output_format)
1242                         revs->diffopt.output_format = DIFF_FORMAT_PATCH;
1243         }
1244         revs->diffopt.abbrev = revs->abbrev;
1245         if (diff_setup_done(&revs->diffopt) < 0)
1246                 die("diff_setup_done failed");
1247
1248         if (revs->grep_filter) {
1249                 revs->grep_filter->all_match = all_match;
1250                 compile_grep_patterns(revs->grep_filter);
1251         }
1252
1253         return left;
1254 }
1255
1256 int prepare_revision_walk(struct rev_info *revs)
1257 {
1258         int nr = revs->pending.nr;
1259         struct object_array_entry *e, *list;
1260
1261         e = list = revs->pending.objects;
1262         revs->pending.nr = 0;
1263         revs->pending.alloc = 0;
1264         revs->pending.objects = NULL;
1265         while (--nr >= 0) {
1266                 struct commit *commit = handle_commit(revs, e->item, e->name);
1267                 if (commit) {
1268                         if (!(commit->object.flags & SEEN)) {
1269                                 commit->object.flags |= SEEN;
1270                                 insert_by_date(commit, &revs->commits);
1271                         }
1272                 }
1273                 e++;
1274         }
1275         free(list);
1276
1277         if (revs->no_walk)
1278                 return 0;
1279         if (revs->limited)
1280                 if (limit_list(revs) < 0)
1281                         return -1;
1282         if (revs->topo_order)
1283                 sort_in_topological_order_fn(&revs->commits, revs->lifo,
1284                                              revs->topo_setter,
1285                                              revs->topo_getter);
1286         return 0;
1287 }
1288
1289 enum rewrite_result {
1290         rewrite_one_ok,
1291         rewrite_one_noparents,
1292         rewrite_one_error,
1293 };
1294
1295 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
1296 {
1297         for (;;) {
1298                 struct commit *p = *pp;
1299                 if (!revs->limited)
1300                         if (add_parents_to_list(revs, p, &revs->commits) < 0)
1301                                 return rewrite_one_error;
1302                 if (p->parents && p->parents->next)
1303                         return rewrite_one_ok;
1304                 if (p->object.flags & (TREECHANGE | UNINTERESTING))
1305                         return rewrite_one_ok;
1306                 if (!p->parents)
1307                         return rewrite_one_noparents;
1308                 *pp = p->parents->item;
1309         }
1310 }
1311
1312 static int rewrite_parents(struct rev_info *revs, struct commit *commit)
1313 {
1314         struct commit_list **pp = &commit->parents;
1315         while (*pp) {
1316                 struct commit_list *parent = *pp;
1317                 switch (rewrite_one(revs, &parent->item)) {
1318                 case rewrite_one_ok:
1319                         break;
1320                 case rewrite_one_noparents:
1321                         *pp = parent->next;
1322                         continue;
1323                 case rewrite_one_error:
1324                         return -1;
1325                 }
1326                 pp = &parent->next;
1327         }
1328         return 0;
1329 }
1330
1331 static int commit_match(struct commit *commit, struct rev_info *opt)
1332 {
1333         if (!opt->grep_filter)
1334                 return 1;
1335         return grep_buffer(opt->grep_filter,
1336                            NULL, /* we say nothing, not even filename */
1337                            commit->buffer, strlen(commit->buffer));
1338 }
1339
1340 static struct commit *get_revision_1(struct rev_info *revs)
1341 {
1342         if (!revs->commits)
1343                 return NULL;
1344
1345         do {
1346                 struct commit_list *entry = revs->commits;
1347                 struct commit *commit = entry->item;
1348
1349                 revs->commits = entry->next;
1350                 free(entry);
1351
1352                 if (revs->reflog_info)
1353                         fake_reflog_parent(revs->reflog_info, commit);
1354
1355                 /*
1356                  * If we haven't done the list limiting, we need to look at
1357                  * the parents here. We also need to do the date-based limiting
1358                  * that we'd otherwise have done in limit_list().
1359                  */
1360                 if (!revs->limited) {
1361                         if (revs->max_age != -1 &&
1362                             (commit->date < revs->max_age))
1363                                 continue;
1364                         if (add_parents_to_list(revs, commit, &revs->commits) < 0)
1365                                 return NULL;
1366                 }
1367                 if (commit->object.flags & SHOWN)
1368                         continue;
1369
1370                 if (revs->unpacked && has_sha1_pack(commit->object.sha1,
1371                                                     revs->ignore_packed))
1372                     continue;
1373
1374                 if (commit->object.flags & UNINTERESTING)
1375                         continue;
1376                 if (revs->min_age != -1 && (commit->date > revs->min_age))
1377                         continue;
1378                 if (revs->no_merges &&
1379                     commit->parents && commit->parents->next)
1380                         continue;
1381                 if (!commit_match(commit, revs))
1382                         continue;
1383                 if (revs->prune_fn && revs->dense) {
1384                         /* Commit without changes? */
1385                         if (!(commit->object.flags & TREECHANGE)) {
1386                                 /* drop merges unless we want parenthood */
1387                                 if (!revs->parents)
1388                                         continue;
1389                                 /* non-merge - always ignore it */
1390                                 if (!commit->parents || !commit->parents->next)
1391                                         continue;
1392                         }
1393                         if (revs->parents && rewrite_parents(revs, commit) < 0)
1394                                 return NULL;
1395                 }
1396                 return commit;
1397         } while (revs->commits);
1398         return NULL;
1399 }
1400
1401 static void gc_boundary(struct object_array *array)
1402 {
1403         unsigned nr = array->nr;
1404         unsigned alloc = array->alloc;
1405         struct object_array_entry *objects = array->objects;
1406
1407         if (alloc <= nr) {
1408                 unsigned i, j;
1409                 for (i = j = 0; i < nr; i++) {
1410                         if (objects[i].item->flags & SHOWN)
1411                                 continue;
1412                         if (i != j)
1413                                 objects[j] = objects[i];
1414                         j++;
1415                 }
1416                 for (i = j; i < nr; i++)
1417                         objects[i].item = NULL;
1418                 array->nr = j;
1419         }
1420 }
1421
1422 struct commit *get_revision(struct rev_info *revs)
1423 {
1424         struct commit *c = NULL;
1425         struct commit_list *l;
1426
1427         if (revs->boundary == 2) {
1428                 unsigned i;
1429                 struct object_array *array = &revs->boundary_commits;
1430                 struct object_array_entry *objects = array->objects;
1431                 for (i = 0; i < array->nr; i++) {
1432                         c = (struct commit *)(objects[i].item);
1433                         if (!c)
1434                                 continue;
1435                         if (!(c->object.flags & CHILD_SHOWN))
1436                                 continue;
1437                         if (!(c->object.flags & SHOWN))
1438                                 break;
1439                 }
1440                 if (array->nr <= i)
1441                         return NULL;
1442
1443                 c->object.flags |= SHOWN | BOUNDARY;
1444                 return c;
1445         }
1446
1447         if (revs->reverse) {
1448                 int limit = -1;
1449
1450                 if (0 <= revs->max_count) {
1451                         limit = revs->max_count;
1452                         if (0 < revs->skip_count)
1453                                 limit += revs->skip_count;
1454                 }
1455                 l = NULL;
1456                 while ((c = get_revision_1(revs))) {
1457                         commit_list_insert(c, &l);
1458                         if ((0 < limit) && !--limit)
1459                                 break;
1460                 }
1461                 revs->commits = l;
1462                 revs->reverse = 0;
1463                 revs->max_count = -1;
1464                 c = NULL;
1465         }
1466
1467         /*
1468          * Now pick up what they want to give us
1469          */
1470         c = get_revision_1(revs);
1471         if (c) {
1472                 while (0 < revs->skip_count) {
1473                         revs->skip_count--;
1474                         c = get_revision_1(revs);
1475                         if (!c)
1476                                 break;
1477                 }
1478         }
1479
1480         /*
1481          * Check the max_count.
1482          */
1483         switch (revs->max_count) {
1484         case -1:
1485                 break;
1486         case 0:
1487                 c = NULL;
1488                 break;
1489         default:
1490                 revs->max_count--;
1491         }
1492
1493         if (c)
1494                 c->object.flags |= SHOWN;
1495
1496         if (!revs->boundary) {
1497                 return c;
1498         }
1499
1500         if (!c) {
1501                 /*
1502                  * get_revision_1() runs out the commits, and
1503                  * we are done computing the boundaries.
1504                  * switch to boundary commits output mode.
1505                  */
1506                 revs->boundary = 2;
1507                 return get_revision(revs);
1508         }
1509
1510         /*
1511          * boundary commits are the commits that are parents of the
1512          * ones we got from get_revision_1() but they themselves are
1513          * not returned from get_revision_1().  Before returning
1514          * 'c', we need to mark its parents that they could be boundaries.
1515          */
1516
1517         for (l = c->parents; l; l = l->next) {
1518                 struct object *p;
1519                 p = &(l->item->object);
1520                 if (p->flags & (CHILD_SHOWN | SHOWN))
1521                         continue;
1522                 p->flags |= CHILD_SHOWN;
1523                 gc_boundary(&revs->boundary_commits);
1524                 add_object_array(p, NULL, &revs->boundary_commits);
1525         }
1526
1527         return c;
1528 }