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 "graph.h"
  10 #include "grep.h"
  11 #include "reflog-walk.h"
  12 #include "patch-ids.h"
  13 #include "decorate.h"
  14 #include "log-tree.h"
  15 #include "string-list.h"
  16
  17 volatile show_early_output_fn_t show_early_output;
  18
  19 char *path_name(const struct name_path *path, const char *name)
  20 {
  21         const struct name_path *p;
  22         char *n, *m;
  23         int nlen = strlen(name);
  24         int len = nlen + 1;
  25
  26         for (p = path; p; p = p->up) {
  27                 if (p->elem_len)
  28                         len += p->elem_len + 1;
  29         }
  30         n = xmalloc(len);
  31         m = n + len - (nlen + 1);
  32         strcpy(m, name);
  33         for (p = path; p; p = p->up) {
  34                 if (p->elem_len) {
  35                         m -= p->elem_len + 1;
  36                         memcpy(m, p->elem, p->elem_len);
  37                         m[p->elem_len] = '/';
  38                 }
  39         }
  40         return n;
  41 }
  42
  43 static int show_path_component_truncated(FILE *out, const char *name, int len)
  44 {
  45         int cnt;
  46         for (cnt = 0; cnt < len; cnt++) {
  47                 int ch = name[cnt];
  48                 if (!ch || ch == '\n')
  49                         return -1;
  50                 fputc(ch, out);
  51         }
  52         return len;
  53 }
  54
  55 static int show_path_truncated(FILE *out, const struct name_path *path)
  56 {
  57         int emitted, ours;
  58
  59         if (!path)
  60                 return 0;
  61         emitted = show_path_truncated(out, path->up);
  62         if (emitted < 0)
  63                 return emitted;
  64         if (emitted)
  65                 fputc('/', out);
  66         ours = show_path_component_truncated(out, path->elem, path->elem_len);
  67         if (ours < 0)
  68                 return ours;
  69         return ours || emitted;
  70 }
  71
  72 void show_object_with_name(FILE *out, struct object *obj, const struct name_path *path, const char *component)
  73 {
  74         struct name_path leaf;
  75         leaf.up = (struct name_path *)path;
  76         leaf.elem = component;
  77         leaf.elem_len = strlen(component);
  78
  79         fprintf(out, "%s ", sha1_to_hex(obj->sha1));
  80         show_path_truncated(out, &leaf);
  81         fputc('\n', out);
  82 }
  83
  84 void add_object(struct object *obj,
  85                 struct object_array *p,
  86                 struct name_path *path,
  87                 const char *name)
  88 {
  89         add_object_array(obj, path_name(path, name), p);
  90 }
  91
  92 static void mark_blob_uninteresting(struct blob *blob)
  93 {
  94         if (!blob)
  95                 return;
  96         if (blob->object.flags & UNINTERESTING)
  97                 return;
  98         blob->object.flags |= UNINTERESTING;
  99 }
 100
 101 void mark_tree_uninteresting(struct tree *tree)
 102 {
 103         struct tree_desc desc;
 104         struct name_entry entry;
 105         struct object *obj = &tree->object;
 106
 107         if (!tree)
 108                 return;
 109         if (obj->flags & UNINTERESTING)
 110                 return;
 111         obj->flags |= UNINTERESTING;
 112         if (!has_sha1_file(obj->sha1))
 113                 return;
 114         if (parse_tree(tree) < 0)
 115                 die("bad tree %s", sha1_to_hex(obj->sha1));
 116
 117         init_tree_desc(&desc, tree->buffer, tree->size);
 118         while (tree_entry(&desc, &entry)) {
 119                 switch (object_type(entry.mode)) {
 120                 case OBJ_TREE:
 121                         mark_tree_uninteresting(lookup_tree(entry.sha1));
 122                         break;
 123                 case OBJ_BLOB:
 124                         mark_blob_uninteresting(lookup_blob(entry.sha1));
 125                         break;
 126                 default:
 127                         /* Subproject commit - not in this repository */
 128                         break;
 129                 }
 130         }
 131
 132         /*
 133          * We don't care about the tree any more
 134          * after it has been marked uninteresting.
 135          */
 136         free(tree->buffer);
 137         tree->buffer = NULL;
 138 }
 139
 140 void mark_parents_uninteresting(struct commit *commit)
 141 {
 142         struct commit_list *parents = NULL, *l;
 143
 144         for (l = commit->parents; l; l = l->next)
 145                 commit_list_insert(l->item, &parents);
 146
 147         while (parents) {
 148                 struct commit *commit = parents->item;
 149                 l = parents;
 150                 parents = parents->next;
 151                 free(l);
 152
 153                 while (commit) {
 154                         /*
 155                          * A missing commit is ok iff its parent is marked
 156                          * uninteresting.
 157                          *
 158                          * We just mark such a thing parsed, so that when
 159                          * it is popped next time around, we won't be trying
 160                          * to parse it and get an error.
 161                          */
 162                         if (!has_sha1_file(commit->object.sha1))
 163                                 commit->object.parsed = 1;
 164
 165                         if (commit->object.flags & UNINTERESTING)
 166                                 break;
 167
 168                         commit->object.flags |= UNINTERESTING;
 169
 170                         /*
 171                          * Normally we haven't parsed the parent
 172                          * yet, so we won't have a parent of a parent
 173                          * here. However, it may turn out that we've
 174                          * reached this commit some other way (where it
 175                          * wasn't uninteresting), in which case we need
 176                          * to mark its parents recursively too..
 177                          */
 178                         if (!commit->parents)
 179                                 break;
 180
 181                         for (l = commit->parents->next; l; l = l->next)
 182                                 commit_list_insert(l->item, &parents);
 183                         commit = commit->parents->item;
 184                 }
 185         }
 186 }
 187
 188 static void add_pending_object_with_mode(struct rev_info *revs, struct object *obj, const char *name, unsigned mode)
 189 {
 190         if (!obj)
 191                 return;
 192         if (revs->no_walk && (obj->flags & UNINTERESTING))
 193                 revs->no_walk = 0;
 194         if (revs->reflog_info && obj->type == OBJ_COMMIT) {
 195                 struct strbuf buf = STRBUF_INIT;
 196                 int len = interpret_branch_name(name, &buf);
 197                 int st;
 198
 199                 if (0 < len && name[len] && buf.len)
 200                         strbuf_addstr(&buf, name + len);
 201                 st = add_reflog_for_walk(revs->reflog_info,
 202                                          (struct commit *)obj,
 203                                          buf.buf[0] ? buf.buf: name);
 204                 strbuf_release(&buf);
 205                 if (st)
 206                         return;
 207         }
 208         add_object_array_with_mode(obj, name, &revs->pending, mode);
 209 }
 210
 211 void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
 212 {
 213         add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
 214 }
 215
 216 void add_head_to_pending(struct rev_info *revs)
 217 {
 218         unsigned char sha1[20];
 219         struct object *obj;
 220         if (get_sha1("HEAD", sha1))
 221                 return;
 222         obj = parse_object(sha1);
 223         if (!obj)
 224                 return;
 225         add_pending_object(revs, obj, "HEAD");
 226 }
 227
 228 static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
 229 {
 230         struct object *object;
 231
 232         object = parse_object(sha1);
 233         if (!object) {
 234                 if (revs->ignore_missing)
 235                         return object;
 236                 die("bad object %s", name);
 237         }
 238         object->flags |= flags;
 239         return object;
 240 }
 241
 242 void add_pending_sha1(struct rev_info *revs, const char *name,
 243                       const unsigned char *sha1, unsigned int flags)
 244 {
 245         struct object *object = get_reference(revs, name, sha1, flags);
 246         add_pending_object(revs, object, name);
 247 }
 248
 249 static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
 250 {
 251         unsigned long flags = object->flags;
 252
 253         /*
 254          * Tag object? Look what it points to..
 255          */
 256         while (object->type == OBJ_TAG) {
 257                 struct tag *tag = (struct tag *) object;
 258                 if (revs->tag_objects && !(flags & UNINTERESTING))
 259                         add_pending_object(revs, object, tag->tag);
 260                 if (!tag->tagged)
 261                         die("bad tag");
 262                 object = parse_object(tag->tagged->sha1);
 263                 if (!object) {
 264                         if (flags & UNINTERESTING)
 265                                 return NULL;
 266                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
 267                 }
 268         }
 269
 270         /*
 271          * Commit object? Just return it, we'll do all the complex
 272          * reachability crud.
 273          */
 274         if (object->type == OBJ_COMMIT) {
 275                 struct commit *commit = (struct commit *)object;
 276                 if (parse_commit(commit) < 0)
 277                         die("unable to parse commit %s", name);
 278                 if (flags & UNINTERESTING) {
 279                         commit->object.flags |= UNINTERESTING;
 280                         mark_parents_uninteresting(commit);
 281                         revs->limited = 1;
 282                 }
 283                 if (revs->show_source && !commit->util)
 284                         commit->util = (void *) name;
 285                 return commit;
 286         }
 287
 288         /*
 289          * Tree object? Either mark it uninteresting, or add it
 290          * to the list of objects to look at later..
 291          */
 292         if (object->type == OBJ_TREE) {
 293                 struct tree *tree = (struct tree *)object;
 294                 if (!revs->tree_objects)
 295                         return NULL;
 296                 if (flags & UNINTERESTING) {
 297                         mark_tree_uninteresting(tree);
 298                         return NULL;
 299                 }
 300                 add_pending_object(revs, object, "");
 301                 return NULL;
 302         }
 303
 304         /*
 305          * Blob object? You know the drill by now..
 306          */
 307         if (object->type == OBJ_BLOB) {
 308                 struct blob *blob = (struct blob *)object;
 309                 if (!revs->blob_objects)
 310                         return NULL;
 311                 if (flags & UNINTERESTING) {
 312                         mark_blob_uninteresting(blob);
 313                         return NULL;
 314                 }
 315                 add_pending_object(revs, object, "");
 316                 return NULL;
 317         }
 318         die("%s is unknown object", name);
 319 }
 320
 321 static int everybody_uninteresting(struct commit_list *orig)
 322 {
 323         struct commit_list *list = orig;
 324         while (list) {
 325                 struct commit *commit = list->item;
 326                 list = list->next;
 327                 if (commit->object.flags & UNINTERESTING)
 328                         continue;
 329                 return 0;
 330         }
 331         return 1;
 332 }
 333
 334 /*
 335  * The goal is to get REV_TREE_NEW as the result only if the
 336  * diff consists of all '+' (and no other changes), REV_TREE_OLD
 337  * if the whole diff is removal of old data, and otherwise
 338  * REV_TREE_DIFFERENT (of course if the trees are the same we
 339  * want REV_TREE_SAME).
 340  * That means that once we get to REV_TREE_DIFFERENT, we do not
 341  * have to look any further.
 342  */
 343 static int tree_difference = REV_TREE_SAME;
 344
 345 static void file_add_remove(struct diff_options *options,
 346                     int addremove, unsigned mode,
 347                     const unsigned char *sha1,
 348                     int sha1_valid,
 349                     const char *fullpath, unsigned dirty_submodule)
 350 {
 351         int diff = addremove == '+' ? REV_TREE_NEW : REV_TREE_OLD;
 352
 353         tree_difference |= diff;
 354         if (tree_difference == REV_TREE_DIFFERENT)
 355                 DIFF_OPT_SET(options, HAS_CHANGES);
 356 }
 357
 358 static void file_change(struct diff_options *options,
 359                  unsigned old_mode, unsigned new_mode,
 360                  const unsigned char *old_sha1,
 361                  const unsigned char *new_sha1,
 362                  int old_sha1_valid, int new_sha1_valid,
 363                  const char *fullpath,
 364                  unsigned old_dirty_submodule, unsigned new_dirty_submodule)
 365 {
 366         tree_difference = REV_TREE_DIFFERENT;
 367         DIFF_OPT_SET(options, HAS_CHANGES);
 368 }
 369
 370 static int rev_compare_tree(struct rev_info *revs, struct commit *parent, struct commit *commit)
 371 {
 372         struct tree *t1 = parent->tree;
 373         struct tree *t2 = commit->tree;
 374
 375         if (!t1)
 376                 return REV_TREE_NEW;
 377         if (!t2)
 378                 return REV_TREE_OLD;
 379
 380         if (revs->simplify_by_decoration) {
 381                 /*
 382                  * If we are simplifying by decoration, then the commit
 383                  * is worth showing if it has a tag pointing at it.
 384                  */
 385                 if (lookup_decoration(&name_decoration, &commit->object))
 386                         return REV_TREE_DIFFERENT;
 387                 /*
 388                  * A commit that is not pointed by a tag is uninteresting
 389                  * if we are not limited by path.  This means that you will
 390                  * see the usual "commits that touch the paths" plus any
 391                  * tagged commit by specifying both --simplify-by-decoration
 392                  * and pathspec.
 393                  */
 394                 if (!revs->prune_data.nr)
 395                         return REV_TREE_SAME;
 396         }
 397
 398         tree_difference = REV_TREE_SAME;
 399         DIFF_OPT_CLR(&revs->pruning, HAS_CHANGES);
 400         if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "",
 401                            &revs->pruning) < 0)
 402                 return REV_TREE_DIFFERENT;
 403         return tree_difference;
 404 }
 405
 406 static int rev_same_tree_as_empty(struct rev_info *revs, struct commit *commit)
 407 {
 408         int retval;
 409         void *tree;
 410         unsigned long size;
 411         struct tree_desc empty, real;
 412         struct tree *t1 = commit->tree;
 413
 414         if (!t1)
 415                 return 0;
 416
 417         tree = read_object_with_reference(t1->object.sha1, tree_type, &size, NULL);
 418         if (!tree)
 419                 return 0;
 420         init_tree_desc(&real, tree, size);
 421         init_tree_desc(&empty, "", 0);
 422
 423         tree_difference = REV_TREE_SAME;
 424         DIFF_OPT_CLR(&revs->pruning, HAS_CHANGES);
 425         retval = diff_tree(&empty, &real, "", &revs->pruning);
 426         free(tree);
 427
 428         return retval >= 0 && (tree_difference == REV_TREE_SAME);
 429 }
 430
 431 static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
 432 {
 433         struct commit_list **pp, *parent;
 434         int tree_changed = 0, tree_same = 0, nth_parent = 0;
 435
 436         /*
 437          * If we don't do pruning, everything is interesting
 438          */
 439         if (!revs->prune)
 440                 return;
 441
 442         if (!commit->tree)
 443                 return;
 444
 445         if (!commit->parents) {
 446                 if (rev_same_tree_as_empty(revs, commit))
 447                         commit->object.flags |= TREESAME;
 448                 return;
 449         }
 450
 451         /*
 452          * Normal non-merge commit? If we don't want to make the
 453          * history dense, we consider it always to be a change..
 454          */
 455         if (!revs->dense && !commit->parents->next)
 456                 return;
 457
 458         pp = &commit->parents;
 459         while ((parent = *pp) != NULL) {
 460                 struct commit *p = parent->item;
 461
 462                 /*
 463                  * Do not compare with later parents when we care only about
 464                  * the first parent chain, in order to avoid derailing the
 465                  * traversal to follow a side branch that brought everything
 466                  * in the path we are limited to by the pathspec.
 467                  */
 468                 if (revs->first_parent_only && nth_parent++)
 469                         break;
 470                 if (parse_commit(p) < 0)
 471                         die("cannot simplify commit %s (because of %s)",
 472                             sha1_to_hex(commit->object.sha1),
 473                             sha1_to_hex(p->object.sha1));
 474                 switch (rev_compare_tree(revs, p, commit)) {
 475                 case REV_TREE_SAME:
 476                         tree_same = 1;
 477                         if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
 478                                 /* Even if a merge with an uninteresting
 479                                  * side branch brought the entire change
 480                                  * we are interested in, we do not want
 481                                  * to lose the other branches of this
 482                                  * merge, so we just keep going.
 483                                  */
 484                                 pp = &parent->next;
 485                                 continue;
 486                         }
 487                         parent->next = NULL;
 488                         commit->parents = parent;
 489                         commit->object.flags |= TREESAME;
 490                         return;
 491
 492                 case REV_TREE_NEW:
 493                         if (revs->remove_empty_trees &&
 494                             rev_same_tree_as_empty(revs, p)) {
 495                                 /* We are adding all the specified
 496                                  * paths from this parent, so the
 497                                  * history beyond this parent is not
 498                                  * interesting.  Remove its parents
 499                                  * (they are grandparents for us).
 500                                  * IOW, we pretend this parent is a
 501                                  * "root" commit.
 502                                  */
 503                                 if (parse_commit(p) < 0)
 504                                         die("cannot simplify commit %s (invalid %s)",
 505                                             sha1_to_hex(commit->object.sha1),
 506                                             sha1_to_hex(p->object.sha1));
 507                                 p->parents = NULL;
 508                         }
 509                 /* fallthrough */
 510                 case REV_TREE_OLD:
 511                 case REV_TREE_DIFFERENT:
 512                         tree_changed = 1;
 513                         pp = &parent->next;
 514                         continue;
 515                 }
 516                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 517         }
 518         if (tree_changed && !tree_same)
 519                 return;
 520         commit->object.flags |= TREESAME;
 521 }
 522
 523 static void commit_list_insert_by_date_cached(struct commit *p, struct commit_list **head,
 524                     struct commit_list *cached_base, struct commit_list **cache)
 525 {
 526         struct commit_list *new_entry;
 527
 528         if (cached_base && p->date < cached_base->item->date)
 529                 new_entry = commit_list_insert_by_date(p, &cached_base->next);
 530         else
 531                 new_entry = commit_list_insert_by_date(p, head);
 532
 533         if (cache && (!*cache || p->date < (*cache)->item->date))
 534                 *cache = new_entry;
 535 }
 536
 537 static int add_parents_to_list(struct rev_info *revs, struct commit *commit,
 538                     struct commit_list **list, struct commit_list **cache_ptr)
 539 {
 540         struct commit_list *parent = commit->parents;
 541         unsigned left_flag;
 542         struct commit_list *cached_base = cache_ptr ? *cache_ptr : NULL;
 543
 544         if (commit->object.flags & ADDED)
 545                 return 0;
 546         commit->object.flags |= ADDED;
 547
 548         /*
 549          * If the commit is uninteresting, don't try to
 550          * prune parents - we want the maximal uninteresting
 551          * set.
 552          *
 553          * Normally we haven't parsed the parent
 554          * yet, so we won't have a parent of a parent
 555          * here. However, it may turn out that we've
 556          * reached this commit some other way (where it
 557          * wasn't uninteresting), in which case we need
 558          * to mark its parents recursively too..
 559          */
 560         if (commit->object.flags & UNINTERESTING) {
 561                 while (parent) {
 562                         struct commit *p = parent->item;
 563                         parent = parent->next;
 564                         if (p)
 565                                 p->object.flags |= UNINTERESTING;
 566                         if (parse_commit(p) < 0)
 567                                 continue;
 568                         if (p->parents)
 569                                 mark_parents_uninteresting(p);
 570                         if (p->object.flags & SEEN)
 571                                 continue;
 572                         p->object.flags |= SEEN;
 573                         commit_list_insert_by_date_cached(p, list, cached_base, cache_ptr);
 574                 }
 575                 return 0;
 576         }
 577
 578         /*
 579          * Ok, the commit wasn't uninteresting. Try to
 580          * simplify the commit history and find the parent
 581          * that has no differences in the path set if one exists.
 582          */
 583         try_to_simplify_commit(revs, commit);
 584
 585         if (revs->no_walk)
 586                 return 0;
 587
 588         left_flag = (commit->object.flags & SYMMETRIC_LEFT);
 589
 590         for (parent = commit->parents; parent; parent = parent->next) {
 591                 struct commit *p = parent->item;
 592
 593                 if (parse_commit(p) < 0)
 594                         return -1;
 595                 if (revs->show_source && !p->util)
 596                         p->util = commit->util;
 597                 p->object.flags |= left_flag;
 598                 if (!(p->object.flags & SEEN)) {
 599                         p->object.flags |= SEEN;
 600                         commit_list_insert_by_date_cached(p, list, cached_base, cache_ptr);
 601                 }
 602                 if (revs->first_parent_only)
 603                         break;
 604         }
 605         return 0;
 606 }
 607
 608 static void cherry_pick_list(struct commit_list *list, struct rev_info *revs)
 609 {
 610         struct commit_list *p;
 611         int left_count = 0, right_count = 0;
 612         int left_first;
 613         struct patch_ids ids;
 614         unsigned cherry_flag;
 615
 616         /* First count the commits on the left and on the right */
 617         for (p = list; p; p = p->next) {
 618                 struct commit *commit = p->item;
 619                 unsigned flags = commit->object.flags;
 620                 if (flags & BOUNDARY)
 621                         ;
 622                 else if (flags & SYMMETRIC_LEFT)
 623                         left_count++;
 624                 else
 625                         right_count++;
 626         }
 627
 628         if (!left_count || !right_count)
 629                 return;
 630
 631         left_first = left_count < right_count;
 632         init_patch_ids(&ids);
 633         ids.diffopts.pathspec = revs->diffopt.pathspec;
 634
 635         /* Compute patch-ids for one side */
 636         for (p = list; p; p = p->next) {
 637                 struct commit *commit = p->item;
 638                 unsigned flags = commit->object.flags;
 639
 640                 if (flags & BOUNDARY)
 641                         continue;
 642                 /*
 643                  * If we have fewer left, left_first is set and we omit
 644                  * commits on the right branch in this loop.  If we have
 645                  * fewer right, we skip the left ones.
 646                  */
 647                 if (left_first != !!(flags & SYMMETRIC_LEFT))
 648                         continue;
 649                 commit->util = add_commit_patch_id(commit, &ids);
 650         }
 651
 652         /* either cherry_mark or cherry_pick are true */
 653         cherry_flag = revs->cherry_mark ? PATCHSAME : SHOWN;
 654
 655         /* Check the other side */
 656         for (p = list; p; p = p->next) {
 657                 struct commit *commit = p->item;
 658                 struct patch_id *id;
 659                 unsigned flags = commit->object.flags;
 660
 661                 if (flags & BOUNDARY)
 662                         continue;
 663                 /*
 664                  * If we have fewer left, left_first is set and we omit
 665                  * commits on the left branch in this loop.
 666                  */
 667                 if (left_first == !!(flags & SYMMETRIC_LEFT))
 668                         continue;
 669
 670                 /*
 671                  * Have we seen the same patch id?
 672                  */
 673                 id = has_commit_patch_id(commit, &ids);
 674                 if (!id)
 675                         continue;
 676                 id->seen = 1;
 677                 commit->object.flags |= cherry_flag;
 678         }
 679
 680         /* Now check the original side for seen ones */
 681         for (p = list; p; p = p->next) {
 682                 struct commit *commit = p->item;
 683                 struct patch_id *ent;
 684
 685                 ent = commit->util;
 686                 if (!ent)
 687                         continue;
 688                 if (ent->seen)
 689                         commit->object.flags |= cherry_flag;
 690                 commit->util = NULL;
 691         }
 692
 693         free_patch_ids(&ids);
 694 }
 695
 696 /* How many extra uninteresting commits we want to see.. */
 697 #define SLOP 5
 698
 699 static int still_interesting(struct commit_list *src, unsigned long date, int slop)
 700 {
 701         /*
 702          * No source list at all? We're definitely done..
 703          */
 704         if (!src)
 705                 return 0;
 706
 707         /*
 708          * Does the destination list contain entries with a date
 709          * before the source list? Definitely _not_ done.
 710          */
 711         if (date < src->item->date)
 712                 return SLOP;
 713
 714         /*
 715          * Does the source list still have interesting commits in
 716          * it? Definitely not done..
 717          */
 718         if (!everybody_uninteresting(src))
 719                 return SLOP;
 720
 721         /* Ok, we're closing in.. */
 722         return slop-1;
 723 }
 724
 725 /*
 726  * "rev-list --ancestry-path A..B" computes commits that are ancestors
 727  * of B but not ancestors of A but further limits the result to those
 728  * that are descendants of A.  This takes the list of bottom commits and
 729  * the result of "A..B" without --ancestry-path, and limits the latter
 730  * further to the ones that can reach one of the commits in "bottom".
 731  */
 732 static void limit_to_ancestry(struct commit_list *bottom, struct commit_list *list)
 733 {
 734         struct commit_list *p;
 735         struct commit_list *rlist = NULL;
 736         int made_progress;
 737
 738         /*
 739          * Reverse the list so that it will be likely that we would
 740          * process parents before children.
 741          */
 742         for (p = list; p; p = p->next)
 743                 commit_list_insert(p->item, &rlist);
 744
 745         for (p = bottom; p; p = p->next)
 746                 p->item->object.flags |= TMP_MARK;
 747
 748         /*
 749          * Mark the ones that can reach bottom commits in "list",
 750          * in a bottom-up fashion.
 751          */
 752         do {
 753                 made_progress = 0;
 754                 for (p = rlist; p; p = p->next) {
 755                         struct commit *c = p->item;
 756                         struct commit_list *parents;
 757                         if (c->object.flags & (TMP_MARK | UNINTERESTING))
 758                                 continue;
 759                         for (parents = c->parents;
 760                              parents;
 761                              parents = parents->next) {
 762                                 if (!(parents->item->object.flags & TMP_MARK))
 763                                         continue;
 764                                 c->object.flags |= TMP_MARK;
 765                                 made_progress = 1;
 766                                 break;
 767                         }
 768                 }
 769         } while (made_progress);
 770
 771         /*
 772          * NEEDSWORK: decide if we want to remove parents that are
 773          * not marked with TMP_MARK from commit->parents for commits
 774          * in the resulting list.  We may not want to do that, though.
 775          */
 776
 777         /*
 778          * The ones that are not marked with TMP_MARK are uninteresting
 779          */
 780         for (p = list; p; p = p->next) {
 781                 struct commit *c = p->item;
 782                 if (c->object.flags & TMP_MARK)
 783                         continue;
 784                 c->object.flags |= UNINTERESTING;
 785         }
 786
 787         /* We are done with the TMP_MARK */
 788         for (p = list; p; p = p->next)
 789                 p->item->object.flags &= ~TMP_MARK;
 790         for (p = bottom; p; p = p->next)
 791                 p->item->object.flags &= ~TMP_MARK;
 792         free_commit_list(rlist);
 793 }
 794
 795 /*
 796  * Before walking the history, keep the set of "negative" refs the
 797  * caller has asked to exclude.
 798  *
 799  * This is used to compute "rev-list --ancestry-path A..B", as we need
 800  * to filter the result of "A..B" further to the ones that can actually
 801  * reach A.
 802  */
 803 static struct commit_list *collect_bottom_commits(struct rev_info *revs)
 804 {
 805         struct commit_list *bottom = NULL;
 806         int i;
 807         for (i = 0; i < revs->cmdline.nr; i++) {
 808                 struct rev_cmdline_entry *elem = &revs->cmdline.rev[i];
 809                 if ((elem->flags & UNINTERESTING) &&
 810                     elem->item->type == OBJ_COMMIT)
 811                         commit_list_insert((struct commit *)elem->item, &bottom);
 812         }
 813         return bottom;
 814 }
 815
 816 /* Assumes either left_only or right_only is set */
 817 static void limit_left_right(struct commit_list *list, struct rev_info *revs)
 818 {
 819         struct commit_list *p;
 820
 821         for (p = list; p; p = p->next) {
 822                 struct commit *commit = p->item;
 823
 824                 if (revs->right_only) {
 825                         if (commit->object.flags & SYMMETRIC_LEFT)
 826                                 commit->object.flags |= SHOWN;
 827                 } else  /* revs->left_only is set */
 828                         if (!(commit->object.flags & SYMMETRIC_LEFT))
 829                                 commit->object.flags |= SHOWN;
 830         }
 831 }
 832
 833 static int limit_list(struct rev_info *revs)
 834 {
 835         int slop = SLOP;
 836         unsigned long date = ~0ul;
 837         struct commit_list *list = revs->commits;
 838         struct commit_list *newlist = NULL;
 839         struct commit_list **p = &newlist;
 840         struct commit_list *bottom = NULL;
 841
 842         if (revs->ancestry_path) {
 843                 bottom = collect_bottom_commits(revs);
 844                 if (!bottom)
 845                         die("--ancestry-path given but there are no bottom commits");
 846         }
 847
 848         while (list) {
 849                 struct commit_list *entry = list;
 850                 struct commit *commit = list->item;
 851                 struct object *obj = &commit->object;
 852                 show_early_output_fn_t show;
 853
 854                 list = list->next;
 855                 free(entry);
 856
 857                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 858                         obj->flags |= UNINTERESTING;
 859                 if (add_parents_to_list(revs, commit, &list, NULL) < 0)
 860                         return -1;
 861                 if (obj->flags & UNINTERESTING) {
 862                         mark_parents_uninteresting(commit);
 863                         if (revs->show_all)
 864                                 p = &commit_list_insert(commit, p)->next;
 865                         slop = still_interesting(list, date, slop);
 866                         if (slop)
 867                                 continue;
 868                         /* If showing all, add the whole pending list to the end */
 869                         if (revs->show_all)
 870                                 *p = list;
 871                         break;
 872                 }
 873                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 874                         continue;
 875                 date = commit->date;
 876                 p = &commit_list_insert(commit, p)->next;
 877
 878                 show = show_early_output;
 879                 if (!show)
 880                         continue;
 881
 882                 show(revs, newlist);
 883                 show_early_output = NULL;
 884         }
 885         if (revs->cherry_pick || revs->cherry_mark)
 886                 cherry_pick_list(newlist, revs);
 887
 888         if (revs->left_only || revs->right_only)
 889                 limit_left_right(newlist, revs);
 890
 891         if (bottom) {
 892                 limit_to_ancestry(bottom, newlist);
 893                 free_commit_list(bottom);
 894         }
 895
 896         revs->commits = newlist;
 897         return 0;
 898 }
 899
 900 static void add_rev_cmdline(struct rev_info *revs,
 901                             struct object *item,
 902                             const char *name,
 903                             int whence,
 904                             unsigned flags)
 905 {
 906         struct rev_cmdline_info *info = &revs->cmdline;
 907         int nr = info->nr;
 908
 909         ALLOC_GROW(info->rev, nr + 1, info->alloc);
 910         info->rev[nr].item = item;
 911         info->rev[nr].name = name;
 912         info->rev[nr].whence = whence;
 913         info->rev[nr].flags = flags;
 914         info->nr++;
 915 }
 916
 917 struct all_refs_cb {
 918         int all_flags;
 919         int warned_bad_reflog;
 920         struct rev_info *all_revs;
 921         const char *name_for_errormsg;
 922 };
 923
 924 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 925 {
 926         struct all_refs_cb *cb = cb_data;
 927         struct object *object = get_reference(cb->all_revs, path, sha1,
 928                                               cb->all_flags);
 929         add_rev_cmdline(cb->all_revs, object, path, REV_CMD_REF, cb->all_flags);
 930         add_pending_sha1(cb->all_revs, path, sha1, cb->all_flags);
 931         return 0;
 932 }
 933
 934 static void init_all_refs_cb(struct all_refs_cb *cb, struct rev_info *revs,
 935         unsigned flags)
 936 {
 937         cb->all_revs = revs;
 938         cb->all_flags = flags;
 939 }
 940
 941 static void handle_refs(const char *submodule, struct rev_info *revs, unsigned flags,
 942                 int (*for_each)(const char *, each_ref_fn, void *))
 943 {
 944         struct all_refs_cb cb;
 945         init_all_refs_cb(&cb, revs, flags);
 946         for_each(submodule, handle_one_ref, &cb);
 947 }
 948
 949 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 950 {
 951         struct all_refs_cb *cb = cb_data;
 952         if (!is_null_sha1(sha1)) {
 953                 struct object *o = parse_object(sha1);
 954                 if (o) {
 955                         o->flags |= cb->all_flags;
 956                         /* ??? CMDLINEFLAGS ??? */
 957                         add_pending_object(cb->all_revs, o, "");
 958                 }
 959                 else if (!cb->warned_bad_reflog) {
 960                         warning("reflog of '%s' references pruned commits",
 961                                 cb->name_for_errormsg);
 962                         cb->warned_bad_reflog = 1;
 963                 }
 964         }
 965 }
 966
 967 static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 968                 const char *email, unsigned long timestamp, int tz,
 969                 const char *message, void *cb_data)
 970 {
 971         handle_one_reflog_commit(osha1, cb_data);
 972         handle_one_reflog_commit(nsha1, cb_data);
 973         return 0;
 974 }
 975
 976 static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 977 {
 978         struct all_refs_cb *cb = cb_data;
 979         cb->warned_bad_reflog = 0;
 980         cb->name_for_errormsg = path;
 981         for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
 982         return 0;
 983 }
 984
 985 static void handle_reflog(struct rev_info *revs, unsigned flags)
 986 {
 987         struct all_refs_cb cb;
 988         cb.all_revs = revs;
 989         cb.all_flags = flags;
 990         for_each_reflog(handle_one_reflog, &cb);
 991 }
 992
 993 static int add_parents_only(struct rev_info *revs, const char *arg_, int flags)
 994 {
 995         unsigned char sha1[20];
 996         struct object *it;
 997         struct commit *commit;
 998         struct commit_list *parents;
 999         const char *arg = arg_;
1000
1001         if (*arg == '^') {
1002                 flags ^= UNINTERESTING;
1003                 arg++;
1004         }
1005         if (get_sha1(arg, sha1))
1006                 return 0;
1007         while (1) {
1008                 it = get_reference(revs, arg, sha1, 0);
1009                 if (!it && revs->ignore_missing)
1010                         return 0;
1011                 if (it->type != OBJ_TAG)
1012                         break;
1013                 if (!((struct tag*)it)->tagged)
1014                         return 0;
1015                 hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
1016         }
1017         if (it->type != OBJ_COMMIT)
1018                 return 0;
1019         commit = (struct commit *)it;
1020         for (parents = commit->parents; parents; parents = parents->next) {
1021                 it = &parents->item->object;
1022                 it->flags |= flags;
1023                 add_rev_cmdline(revs, it, arg_, REV_CMD_PARENTS_ONLY, flags);
1024                 add_pending_object(revs, it, arg);
1025         }
1026         return 1;
1027 }
1028
1029 void init_revisions(struct rev_info *revs, const char *prefix)
1030 {
1031         memset(revs, 0, sizeof(*revs));
1032
1033         revs->abbrev = DEFAULT_ABBREV;
1034         revs->ignore_merges = 1;
1035         revs->simplify_history = 1;
1036         DIFF_OPT_SET(&revs->pruning, RECURSIVE);
1037         DIFF_OPT_SET(&revs->pruning, QUICK);
1038         revs->pruning.add_remove = file_add_remove;
1039         revs->pruning.change = file_change;
1040         revs->lifo = 1;
1041         revs->dense = 1;
1042         revs->prefix = prefix;
1043         revs->max_age = -1;
1044         revs->min_age = -1;
1045         revs->skip_count = -1;
1046         revs->max_count = -1;
1047         revs->max_parents = -1;
1048
1049         revs->commit_format = CMIT_FMT_DEFAULT;
1050
1051         revs->grep_filter.status_only = 1;
1052         revs->grep_filter.pattern_tail = &(revs->grep_filter.pattern_list);
1053         revs->grep_filter.header_tail = &(revs->grep_filter.header_list);
1054         revs->grep_filter.regflags = REG_NEWLINE;
1055
1056         diff_setup(&revs->diffopt);
1057         if (prefix && !revs->diffopt.prefix) {
1058                 revs->diffopt.prefix = prefix;
1059                 revs->diffopt.prefix_length = strlen(prefix);
1060         }
1061
1062         revs->notes_opt.use_default_notes = -1;
1063 }
1064
1065 static void add_pending_commit_list(struct rev_info *revs,
1066                                     struct commit_list *commit_list,
1067                                     unsigned int flags)
1068 {
1069         while (commit_list) {
1070                 struct object *object = &commit_list->item->object;
1071                 object->flags |= flags;
1072                 add_pending_object(revs, object, sha1_to_hex(object->sha1));
1073                 commit_list = commit_list->next;
1074         }
1075 }
1076
1077 static void prepare_show_merge(struct rev_info *revs)
1078 {
1079         struct commit_list *bases;
1080         struct commit *head, *other;
1081         unsigned char sha1[20];
1082         const char **prune = NULL;
1083         int i, prune_num = 1; /* counting terminating NULL */
1084
1085         if (get_sha1("HEAD", sha1))
1086                 die("--merge without HEAD?");
1087         head = lookup_commit_or_die(sha1, "HEAD");
1088         if (get_sha1("MERGE_HEAD", sha1))
1089                 die("--merge without MERGE_HEAD?");
1090         other = lookup_commit_or_die(sha1, "MERGE_HEAD");
1091         add_pending_object(revs, &head->object, "HEAD");
1092         add_pending_object(revs, &other->object, "MERGE_HEAD");
1093         bases = get_merge_bases(head, other, 1);
1094         add_pending_commit_list(revs, bases, UNINTERESTING);
1095         free_commit_list(bases);
1096         head->object.flags |= SYMMETRIC_LEFT;
1097
1098         if (!active_nr)
1099                 read_cache();
1100         for (i = 0; i < active_nr; i++) {
1101                 struct cache_entry *ce = active_cache[i];
1102                 if (!ce_stage(ce))
1103                         continue;
1104                 if (ce_path_match(ce, &revs->prune_data)) {
1105                         prune_num++;
1106                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
1107                         prune[prune_num-2] = ce->name;
1108                         prune[prune_num-1] = NULL;
1109                 }
1110                 while ((i+1 < active_nr) &&
1111                        ce_same_name(ce, active_cache[i+1]))
1112                         i++;
1113         }
1114         free_pathspec(&revs->prune_data);
1115         init_pathspec(&revs->prune_data, prune);
1116         revs->limited = 1;
1117 }
1118
1119 int handle_revision_arg(const char *arg_, struct rev_info *revs,
1120                         int flags,
1121                         int cant_be_filename)
1122 {
1123         unsigned mode;
1124         char *dotdot;
1125         struct object *object;
1126         unsigned char sha1[20];
1127         int local_flags;
1128         const char *arg = arg_;
1129
1130         dotdot = strstr(arg, "..");
1131         if (dotdot) {
1132                 unsigned char from_sha1[20];
1133                 const char *next = dotdot + 2;
1134                 const char *this = arg;
1135                 int symmetric = *next == '.';
1136                 unsigned int flags_exclude = flags ^ UNINTERESTING;
1137                 unsigned int a_flags;
1138
1139                 *dotdot = 0;
1140                 next += symmetric;
1141
1142                 if (!*next)
1143                         next = "HEAD";
1144                 if (dotdot == arg)
1145                         this = "HEAD";
1146                 if (!get_sha1(this, from_sha1) &&
1147                     !get_sha1(next, sha1)) {
1148                         struct commit *a, *b;
1149                         struct commit_list *exclude;
1150
1151                         a = lookup_commit_reference(from_sha1);
1152                         b = lookup_commit_reference(sha1);
1153                         if (!a || !b) {
1154                                 if (revs->ignore_missing)
1155                                         return 0;
1156                                 die(symmetric ?
1157                                     "Invalid symmetric difference expression %s...%s" :
1158                                     "Invalid revision range %s..%s",
1159                                     arg, next);
1160                         }
1161
1162                         if (!cant_be_filename) {
1163                                 *dotdot = '.';
1164                                 verify_non_filename(revs->prefix, arg);
1165                         }
1166
1167                         if (symmetric) {
1168                                 exclude = get_merge_bases(a, b, 1);
1169                                 add_pending_commit_list(revs, exclude,
1170                                                         flags_exclude);
1171                                 free_commit_list(exclude);
1172                                 a_flags = flags | SYMMETRIC_LEFT;
1173                         } else
1174                                 a_flags = flags_exclude;
1175                         a->object.flags |= a_flags;
1176                         b->object.flags |= flags;
1177                         add_rev_cmdline(revs, &a->object, this,
1178                                         REV_CMD_LEFT, a_flags);
1179                         add_rev_cmdline(revs, &b->object, next,
1180                                         REV_CMD_RIGHT, flags);
1181                         add_pending_object(revs, &a->object, this);
1182                         add_pending_object(revs, &b->object, next);
1183                         return 0;
1184                 }
1185                 *dotdot = '.';
1186         }
1187         dotdot = strstr(arg, "^@");
1188         if (dotdot && !dotdot[2]) {
1189                 *dotdot = 0;
1190                 if (add_parents_only(revs, arg, flags))
1191                         return 0;
1192                 *dotdot = '^';
1193         }
1194         dotdot = strstr(arg, "^!");
1195         if (dotdot && !dotdot[2]) {
1196                 *dotdot = 0;
1197                 if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
1198                         *dotdot = '^';
1199         }
1200
1201         local_flags = 0;
1202         if (*arg == '^') {
1203                 local_flags = UNINTERESTING;
1204                 arg++;
1205         }
1206         if (get_sha1_with_mode(arg, sha1, &mode))
1207                 return revs->ignore_missing ? 0 : -1;
1208         if (!cant_be_filename)
1209                 verify_non_filename(revs->prefix, arg);
1210         object = get_reference(revs, arg, sha1, flags ^ local_flags);
1211         add_rev_cmdline(revs, object, arg_, REV_CMD_REV, flags ^ local_flags);
1212         add_pending_object_with_mode(revs, object, arg, mode);
1213         return 0;
1214 }
1215
1216 struct cmdline_pathspec {
1217         int alloc;
1218         int nr;
1219         const char **path;
1220 };
1221
1222 static void append_prune_data(struct cmdline_pathspec *prune, const char **av)
1223 {
1224         while (*av) {
1225                 ALLOC_GROW(prune->path, prune->nr+1, prune->alloc);
1226                 prune->path[prune->nr++] = *(av++);
1227         }
1228 }
1229
1230 static void read_pathspec_from_stdin(struct rev_info *revs, struct strbuf *sb,
1231                                      struct cmdline_pathspec *prune)
1232 {
1233         while (strbuf_getwholeline(sb, stdin, '\n') != EOF) {
1234                 int len = sb->len;
1235                 if (len && sb->buf[len - 1] == '\n')
1236                         sb->buf[--len] = '\0';
1237                 ALLOC_GROW(prune->path, prune->nr+1, prune->alloc);
1238                 prune->path[prune->nr++] = xstrdup(sb->buf);
1239         }
1240 }
1241
1242 static void read_revisions_from_stdin(struct rev_info *revs,
1243                                       struct cmdline_pathspec *prune)
1244 {
1245         struct strbuf sb;
1246         int seen_dashdash = 0;
1247
1248         strbuf_init(&sb, 1000);
1249         while (strbuf_getwholeline(&sb, stdin, '\n') != EOF) {
1250                 int len = sb.len;
1251                 if (len && sb.buf[len - 1] == '\n')
1252                         sb.buf[--len] = '\0';
1253                 if (!len)
1254                         break;
1255                 if (sb.buf[0] == '-') {
1256                         if (len == 2 && sb.buf[1] == '-') {
1257                                 seen_dashdash = 1;
1258                                 break;
1259                         }
1260                         die("options not supported in --stdin mode");
1261                 }
1262                 if (handle_revision_arg(sb.buf, revs, 0, 1))
1263                         die("bad revision '%s'", sb.buf);
1264         }
1265         if (seen_dashdash)
1266                 read_pathspec_from_stdin(revs, &sb, prune);
1267         strbuf_release(&sb);
1268 }
1269
1270 static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
1271 {
1272         append_grep_pattern(&revs->grep_filter, ptn, "command line", 0, what);
1273 }
1274
1275 static void add_header_grep(struct rev_info *revs, enum grep_header_field field, const char *pattern)
1276 {
1277         append_header_grep_pattern(&revs->grep_filter, field, pattern);
1278 }
1279
1280 static void add_message_grep(struct rev_info *revs, const char *pattern)
1281 {
1282         add_grep(revs, pattern, GREP_PATTERN_BODY);
1283 }
1284
1285 static int handle_revision_opt(struct rev_info *revs, int argc, const char **argv,
1286                                int *unkc, const char **unkv)
1287 {
1288         const char *arg = argv[0];
1289         const char *optarg;
1290         int argcount;
1291
1292         /* pseudo revision arguments */
1293         if (!strcmp(arg, "--all") || !strcmp(arg, "--branches") ||
1294             !strcmp(arg, "--tags") || !strcmp(arg, "--remotes") ||
1295             !strcmp(arg, "--reflog") || !strcmp(arg, "--not") ||
1296             !strcmp(arg, "--no-walk") || !strcmp(arg, "--do-walk") ||
1297             !strcmp(arg, "--bisect") || !prefixcmp(arg, "--glob=") ||
1298             !prefixcmp(arg, "--branches=") || !prefixcmp(arg, "--tags=") ||
1299             !prefixcmp(arg, "--remotes="))
1300         {
1301                 unkv[(*unkc)++] = arg;
1302                 return 1;
1303         }
1304
1305         if ((argcount = parse_long_opt("max-count", argv, &optarg))) {
1306                 revs->max_count = atoi(optarg);
1307                 revs->no_walk = 0;
1308                 return argcount;
1309         } else if ((argcount = parse_long_opt("skip", argv, &optarg))) {
1310                 revs->skip_count = atoi(optarg);
1311                 return argcount;
1312         } else if ((*arg == '-') && isdigit(arg[1])) {
1313         /* accept -<digit>, like traditional "head" */
1314                 revs->max_count = atoi(arg + 1);
1315                 revs->no_walk = 0;
1316         } else if (!strcmp(arg, "-n")) {
1317                 if (argc <= 1)
1318                         return error("-n requires an argument");
1319                 revs->max_count = atoi(argv[1]);
1320                 revs->no_walk = 0;
1321                 return 2;
1322         } else if (!prefixcmp(arg, "-n")) {
1323                 revs->max_count = atoi(arg + 2);
1324                 revs->no_walk = 0;
1325         } else if ((argcount = parse_long_opt("max-age", argv, &optarg))) {
1326                 revs->max_age = atoi(optarg);
1327                 return argcount;
1328         } else if ((argcount = parse_long_opt("since", argv, &optarg))) {
1329                 revs->max_age = approxidate(optarg);
1330                 return argcount;
1331         } else if ((argcount = parse_long_opt("after", argv, &optarg))) {
1332                 revs->max_age = approxidate(optarg);
1333                 return argcount;
1334         } else if ((argcount = parse_long_opt("min-age", argv, &optarg))) {
1335                 revs->min_age = atoi(optarg);
1336                 return argcount;
1337         } else if ((argcount = parse_long_opt("before", argv, &optarg))) {
1338                 revs->min_age = approxidate(optarg);
1339                 return argcount;
1340         } else if ((argcount = parse_long_opt("until", argv, &optarg))) {
1341                 revs->min_age = approxidate(optarg);
1342                 return argcount;
1343         } else if (!strcmp(arg, "--first-parent")) {
1344                 revs->first_parent_only = 1;
1345         } else if (!strcmp(arg, "--ancestry-path")) {
1346                 revs->ancestry_path = 1;
1347                 revs->simplify_history = 0;
1348                 revs->limited = 1;
1349         } else if (!strcmp(arg, "-g") || !strcmp(arg, "--walk-reflogs")) {
1350                 init_reflog_walk(&revs->reflog_info);
1351         } else if (!strcmp(arg, "--default")) {
1352                 if (argc <= 1)
1353                         return error("bad --default argument");
1354                 revs->def = argv[1];
1355                 return 2;
1356         } else if (!strcmp(arg, "--merge")) {
1357                 revs->show_merge = 1;
1358         } else if (!strcmp(arg, "--topo-order")) {
1359                 revs->lifo = 1;
1360                 revs->topo_order = 1;
1361         } else if (!strcmp(arg, "--simplify-merges")) {
1362                 revs->simplify_merges = 1;
1363                 revs->topo_order = 1;
1364                 revs->rewrite_parents = 1;
1365                 revs->simplify_history = 0;
1366                 revs->limited = 1;
1367         } else if (!strcmp(arg, "--simplify-by-decoration")) {
1368                 revs->simplify_merges = 1;
1369                 revs->topo_order = 1;
1370                 revs->rewrite_parents = 1;
1371                 revs->simplify_history = 0;
1372                 revs->simplify_by_decoration = 1;
1373                 revs->limited = 1;
1374                 revs->prune = 1;
1375                 load_ref_decorations(DECORATE_SHORT_REFS);
1376         } else if (!strcmp(arg, "--date-order")) {
1377                 revs->lifo = 0;
1378                 revs->topo_order = 1;
1379         } else if (!prefixcmp(arg, "--early-output")) {
1380                 int count = 100;
1381                 switch (arg[14]) {
1382                 case '=':
1383                         count = atoi(arg+15);
1384                         /* Fallthrough */
1385                 case 0:
1386                         revs->topo_order = 1;
1387                        revs->early_output = count;
1388                 }
1389         } else if (!strcmp(arg, "--parents")) {
1390                 revs->rewrite_parents = 1;
1391                 revs->print_parents = 1;
1392         } else if (!strcmp(arg, "--dense")) {
1393                 revs->dense = 1;
1394         } else if (!strcmp(arg, "--sparse")) {
1395                 revs->dense = 0;
1396         } else if (!strcmp(arg, "--show-all")) {
1397                 revs->show_all = 1;
1398         } else if (!strcmp(arg, "--remove-empty")) {
1399                 revs->remove_empty_trees = 1;
1400         } else if (!strcmp(arg, "--merges")) {
1401                 revs->min_parents = 2;
1402         } else if (!strcmp(arg, "--no-merges")) {
1403                 revs->max_parents = 1;
1404         } else if (!prefixcmp(arg, "--min-parents=")) {
1405                 revs->min_parents = atoi(arg+14);
1406         } else if (!prefixcmp(arg, "--no-min-parents")) {
1407                 revs->min_parents = 0;
1408         } else if (!prefixcmp(arg, "--max-parents=")) {
1409                 revs->max_parents = atoi(arg+14);
1410         } else if (!prefixcmp(arg, "--no-max-parents")) {
1411                 revs->max_parents = -1;
1412         } else if (!strcmp(arg, "--boundary")) {
1413                 revs->boundary = 1;
1414         } else if (!strcmp(arg, "--left-right")) {
1415                 revs->left_right = 1;
1416         } else if (!strcmp(arg, "--left-only")) {
1417                 if (revs->right_only)
1418                         die("--left-only is incompatible with --right-only"
1419                             " or --cherry");
1420                 revs->left_only = 1;
1421         } else if (!strcmp(arg, "--right-only")) {
1422                 if (revs->left_only)
1423                         die("--right-only is incompatible with --left-only");
1424                 revs->right_only = 1;
1425         } else if (!strcmp(arg, "--cherry")) {
1426                 if (revs->left_only)
1427                         die("--cherry is incompatible with --left-only");
1428                 revs->cherry_mark = 1;
1429                 revs->right_only = 1;
1430                 revs->max_parents = 1;
1431                 revs->limited = 1;
1432         } else if (!strcmp(arg, "--count")) {
1433                 revs->count = 1;
1434         } else if (!strcmp(arg, "--cherry-mark")) {
1435                 if (revs->cherry_pick)
1436                         die("--cherry-mark is incompatible with --cherry-pick");
1437                 revs->cherry_mark = 1;
1438                 revs->limited = 1; /* needs limit_list() */
1439         } else if (!strcmp(arg, "--cherry-pick")) {
1440                 if (revs->cherry_mark)
1441                         die("--cherry-pick is incompatible with --cherry-mark");
1442                 revs->cherry_pick = 1;
1443                 revs->limited = 1;
1444         } else if (!strcmp(arg, "--objects")) {
1445                 revs->tag_objects = 1;
1446                 revs->tree_objects = 1;
1447                 revs->blob_objects = 1;
1448         } else if (!strcmp(arg, "--objects-edge")) {
1449                 revs->tag_objects = 1;
1450                 revs->tree_objects = 1;
1451                 revs->blob_objects = 1;
1452                 revs->edge_hint = 1;
1453         } else if (!strcmp(arg, "--verify-objects")) {
1454                 revs->tag_objects = 1;
1455                 revs->tree_objects = 1;
1456                 revs->blob_objects = 1;
1457                 revs->verify_objects = 1;
1458         } else if (!strcmp(arg, "--unpacked")) {
1459                 revs->unpacked = 1;
1460         } else if (!prefixcmp(arg, "--unpacked=")) {
1461                 die("--unpacked=<packfile> no longer supported.");
1462         } else if (!strcmp(arg, "-r")) {
1463                 revs->diff = 1;
1464                 DIFF_OPT_SET(&revs->diffopt, RECURSIVE);
1465         } else if (!strcmp(arg, "-t")) {
1466                 revs->diff = 1;
1467                 DIFF_OPT_SET(&revs->diffopt, RECURSIVE);
1468                 DIFF_OPT_SET(&revs->diffopt, TREE_IN_RECURSIVE);
1469         } else if (!strcmp(arg, "-m")) {
1470                 revs->ignore_merges = 0;
1471         } else if (!strcmp(arg, "-c")) {
1472                 revs->diff = 1;
1473                 revs->dense_combined_merges = 0;
1474                 revs->combine_merges = 1;
1475         } else if (!strcmp(arg, "--cc")) {
1476                 revs->diff = 1;
1477                 revs->dense_combined_merges = 1;
1478                 revs->combine_merges = 1;
1479         } else if (!strcmp(arg, "-v")) {
1480                 revs->verbose_header = 1;
1481         } else if (!strcmp(arg, "--pretty")) {
1482                 revs->verbose_header = 1;
1483                 revs->pretty_given = 1;
1484                 get_commit_format(arg+8, revs);
1485         } else if (!prefixcmp(arg, "--pretty=") || !prefixcmp(arg, "--format=")) {
1486                 /*
1487                  * Detached form ("--pretty X" as opposed to "--pretty=X")
1488                  * not allowed, since the argument is optional.
1489                  */
1490                 revs->verbose_header = 1;
1491                 revs->pretty_given = 1;
1492                 get_commit_format(arg+9, revs);
1493         } else if (!strcmp(arg, "--show-notes") || !strcmp(arg, "--notes")) {
1494                 revs->show_notes = 1;
1495                 revs->show_notes_given = 1;
1496                 revs->notes_opt.use_default_notes = 1;
1497         } else if (!strcmp(arg, "--show-signature")) {
1498                 revs->show_signature = 1;
1499         } else if (!prefixcmp(arg, "--show-notes=") ||
1500                    !prefixcmp(arg, "--notes=")) {
1501                 struct strbuf buf = STRBUF_INIT;
1502                 revs->show_notes = 1;
1503                 revs->show_notes_given = 1;
1504                 if (!prefixcmp(arg, "--show-notes")) {
1505                         if (revs->notes_opt.use_default_notes < 0)
1506                                 revs->notes_opt.use_default_notes = 1;
1507                         strbuf_addstr(&buf, arg+13);
1508                 }
1509                 else
1510                         strbuf_addstr(&buf, arg+8);
1511                 expand_notes_ref(&buf);
1512                 string_list_append(&revs->notes_opt.extra_notes_refs,
1513                                    strbuf_detach(&buf, NULL));
1514         } else if (!strcmp(arg, "--no-notes")) {
1515                 revs->show_notes = 0;
1516                 revs->show_notes_given = 1;
1517                 revs->notes_opt.use_default_notes = -1;
1518                 /* we have been strdup'ing ourselves, so trick
1519                  * string_list into free()ing strings */
1520                 revs->notes_opt.extra_notes_refs.strdup_strings = 1;
1521                 string_list_clear(&revs->notes_opt.extra_notes_refs, 0);
1522                 revs->notes_opt.extra_notes_refs.strdup_strings = 0;
1523         } else if (!strcmp(arg, "--standard-notes")) {
1524                 revs->show_notes_given = 1;
1525                 revs->notes_opt.use_default_notes = 1;
1526         } else if (!strcmp(arg, "--no-standard-notes")) {
1527                 revs->notes_opt.use_default_notes = 0;
1528         } else if (!strcmp(arg, "--oneline")) {
1529                 revs->verbose_header = 1;
1530                 get_commit_format("oneline", revs);
1531                 revs->pretty_given = 1;
1532                 revs->abbrev_commit = 1;
1533         } else if (!strcmp(arg, "--graph")) {
1534                 revs->topo_order = 1;
1535                 revs->rewrite_parents = 1;
1536                 revs->graph = graph_init(revs);
1537         } else if (!strcmp(arg, "--root")) {
1538                 revs->show_root_diff = 1;
1539         } else if (!strcmp(arg, "--no-commit-id")) {
1540                 revs->no_commit_id = 1;
1541         } else if (!strcmp(arg, "--always")) {
1542                 revs->always_show_header = 1;
1543         } else if (!strcmp(arg, "--no-abbrev")) {
1544                 revs->abbrev = 0;
1545         } else if (!strcmp(arg, "--abbrev")) {
1546                 revs->abbrev = DEFAULT_ABBREV;
1547         } else if (!prefixcmp(arg, "--abbrev=")) {
1548                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1549                 if (revs->abbrev < MINIMUM_ABBREV)
1550                         revs->abbrev = MINIMUM_ABBREV;
1551                 else if (revs->abbrev > 40)
1552                         revs->abbrev = 40;
1553         } else if (!strcmp(arg, "--abbrev-commit")) {
1554                 revs->abbrev_commit = 1;
1555                 revs->abbrev_commit_given = 1;
1556         } else if (!strcmp(arg, "--no-abbrev-commit")) {
1557                 revs->abbrev_commit = 0;
1558         } else if (!strcmp(arg, "--full-diff")) {
1559                 revs->diff = 1;
1560                 revs->full_diff = 1;
1561         } else if (!strcmp(arg, "--full-history")) {
1562                 revs->simplify_history = 0;
1563         } else if (!strcmp(arg, "--relative-date")) {
1564                 revs->date_mode = DATE_RELATIVE;
1565                 revs->date_mode_explicit = 1;
1566         } else if ((argcount = parse_long_opt("date", argv, &optarg))) {
1567                 revs->date_mode = parse_date_format(optarg);
1568                 revs->date_mode_explicit = 1;
1569                 return argcount;
1570         } else if (!strcmp(arg, "--log-size")) {
1571                 revs->show_log_size = 1;
1572         }
1573         /*
1574          * Grepping the commit log
1575          */
1576         else if ((argcount = parse_long_opt("author", argv, &optarg))) {
1577                 add_header_grep(revs, GREP_HEADER_AUTHOR, optarg);
1578                 return argcount;
1579         } else if ((argcount = parse_long_opt("committer", argv, &optarg))) {
1580                 add_header_grep(revs, GREP_HEADER_COMMITTER, optarg);
1581                 return argcount;
1582         } else if ((argcount = parse_long_opt("grep", argv, &optarg))) {
1583                 add_message_grep(revs, optarg);
1584                 return argcount;
1585         } else if (!strcmp(arg, "--extended-regexp") || !strcmp(arg, "-E")) {
1586                 revs->grep_filter.regflags |= REG_EXTENDED;
1587         } else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
1588                 revs->grep_filter.regflags |= REG_ICASE;
1589                 DIFF_OPT_SET(&revs->diffopt, PICKAXE_IGNORE_CASE);
1590         } else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {
1591                 revs->grep_filter.fixed = 1;
1592         } else if (!strcmp(arg, "--all-match")) {
1593                 revs->grep_filter.all_match = 1;
1594         } else if ((argcount = parse_long_opt("encoding", argv, &optarg))) {
1595                 if (strcmp(optarg, "none"))
1596                         git_log_output_encoding = xstrdup(optarg);
1597                 else
1598                         git_log_output_encoding = "";
1599                 return argcount;
1600         } else if (!strcmp(arg, "--reverse")) {
1601                 revs->reverse ^= 1;
1602         } else if (!strcmp(arg, "--children")) {
1603                 revs->children.name = "children";
1604                 revs->limited = 1;
1605         } else if (!strcmp(arg, "--ignore-missing")) {
1606                 revs->ignore_missing = 1;
1607         } else {
1608                 int opts = diff_opt_parse(&revs->diffopt, argv, argc);
1609                 if (!opts)
1610                         unkv[(*unkc)++] = arg;
1611                 return opts;
1612         }
1613
1614         return 1;
1615 }
1616
1617 void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
1618                         const struct option *options,
1619                         const char * const usagestr[])
1620 {
1621         int n = handle_revision_opt(revs, ctx->argc, ctx->argv,
1622                                     &ctx->cpidx, ctx->out);
1623         if (n <= 0) {
1624                 error("unknown option `%s'", ctx->argv[0]);
1625                 usage_with_options(usagestr, options);
1626         }
1627         ctx->argv += n;
1628         ctx->argc -= n;
1629 }
1630
1631 static int for_each_bad_bisect_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1632 {
1633         return for_each_ref_in_submodule(submodule, "refs/bisect/bad", fn, cb_data);
1634 }
1635
1636 static int for_each_good_bisect_ref(const char *submodule, each_ref_fn fn, void *cb_data)
1637 {
1638         return for_each_ref_in_submodule(submodule, "refs/bisect/good", fn, cb_data);
1639 }
1640
1641 static int handle_revision_pseudo_opt(const char *submodule,
1642                                 struct rev_info *revs,
1643                                 int argc, const char **argv, int *flags)
1644 {
1645         const char *arg = argv[0];
1646         const char *optarg;
1647         int argcount;
1648
1649         /*
1650          * NOTE!
1651          *
1652          * Commands like "git shortlog" will not accept the options below
1653          * unless parse_revision_opt queues them (as opposed to erroring
1654          * out).
1655          *
1656          * When implementing your new pseudo-option, remember to
1657          * register it in the list at the top of handle_revision_opt.
1658          */
1659         if (!strcmp(arg, "--all")) {
1660                 handle_refs(submodule, revs, *flags, for_each_ref_submodule);
1661                 handle_refs(submodule, revs, *flags, head_ref_submodule);
1662         } else if (!strcmp(arg, "--branches")) {
1663                 handle_refs(submodule, revs, *flags, for_each_branch_ref_submodule);
1664         } else if (!strcmp(arg, "--bisect")) {
1665                 handle_refs(submodule, revs, *flags, for_each_bad_bisect_ref);
1666                 handle_refs(submodule, revs, *flags ^ UNINTERESTING, for_each_good_bisect_ref);
1667                 revs->bisect = 1;
1668         } else if (!strcmp(arg, "--tags")) {
1669                 handle_refs(submodule, revs, *flags, for_each_tag_ref_submodule);
1670         } else if (!strcmp(arg, "--remotes")) {
1671                 handle_refs(submodule, revs, *flags, for_each_remote_ref_submodule);
1672         } else if ((argcount = parse_long_opt("glob", argv, &optarg))) {
1673                 struct all_refs_cb cb;
1674                 init_all_refs_cb(&cb, revs, *flags);
1675                 for_each_glob_ref(handle_one_ref, optarg, &cb);
1676                 return argcount;
1677         } else if (!prefixcmp(arg, "--branches=")) {
1678                 struct all_refs_cb cb;
1679                 init_all_refs_cb(&cb, revs, *flags);
1680                 for_each_glob_ref_in(handle_one_ref, arg + 11, "refs/heads/", &cb);
1681         } else if (!prefixcmp(arg, "--tags=")) {
1682                 struct all_refs_cb cb;
1683                 init_all_refs_cb(&cb, revs, *flags);
1684                 for_each_glob_ref_in(handle_one_ref, arg + 7, "refs/tags/", &cb);
1685         } else if (!prefixcmp(arg, "--remotes=")) {
1686                 struct all_refs_cb cb;
1687                 init_all_refs_cb(&cb, revs, *flags);
1688                 for_each_glob_ref_in(handle_one_ref, arg + 10, "refs/remotes/", &cb);
1689         } else if (!strcmp(arg, "--reflog")) {
1690                 handle_reflog(revs, *flags);
1691         } else if (!strcmp(arg, "--not")) {
1692                 *flags ^= UNINTERESTING;
1693         } else if (!strcmp(arg, "--no-walk")) {
1694                 revs->no_walk = 1;
1695         } else if (!strcmp(arg, "--do-walk")) {
1696                 revs->no_walk = 0;
1697         } else {
1698                 return 0;
1699         }
1700
1701         return 1;
1702 }
1703
1704 /*
1705  * Parse revision information, filling in the "rev_info" structure,
1706  * and removing the used arguments from the argument list.
1707  *
1708  * Returns the number of arguments left that weren't recognized
1709  * (which are also moved to the head of the argument list)
1710  */
1711 int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct setup_revision_opt *opt)
1712 {
1713         int i, flags, left, seen_dashdash, read_from_stdin, got_rev_arg = 0;
1714         struct cmdline_pathspec prune_data;
1715         const char *submodule = NULL;
1716
1717         memset(&prune_data, 0, sizeof(prune_data));
1718         if (opt)
1719                 submodule = opt->submodule;
1720
1721         /* First, search for "--" */
1722         if (opt && opt->assume_dashdash) {
1723                 seen_dashdash = 1;
1724         } else {
1725                 seen_dashdash = 0;
1726                 for (i = 1; i < argc; i++) {
1727                         const char *arg = argv[i];
1728                         if (strcmp(arg, "--"))
1729                                 continue;
1730                         argv[i] = NULL;
1731                         argc = i;
1732                         if (argv[i + 1])
1733                                 append_prune_data(&prune_data, argv + i + 1);
1734                         seen_dashdash = 1;
1735                         break;
1736                 }
1737         }
1738
1739         /* Second, deal with arguments and options */
1740         flags = 0;
1741         read_from_stdin = 0;
1742         for (left = i = 1; i < argc; i++) {
1743                 const char *arg = argv[i];
1744                 if (*arg == '-') {
1745                         int opts;
1746
1747                         opts = handle_revision_pseudo_opt(submodule,
1748                                                 revs, argc - i, argv + i,
1749                                                 &flags);
1750                         if (opts > 0) {
1751                                 i += opts - 1;
1752                                 continue;
1753                         }
1754
1755                         if (!strcmp(arg, "--stdin")) {
1756                                 if (revs->disable_stdin) {
1757                                         argv[left++] = arg;
1758                                         continue;
1759                                 }
1760                                 if (read_from_stdin++)
1761                                         die("--stdin given twice?");
1762                                 read_revisions_from_stdin(revs, &prune_data);
1763                                 continue;
1764                         }
1765
1766                         opts = handle_revision_opt(revs, argc - i, argv + i, &left, argv);
1767                         if (opts > 0) {
1768                                 i += opts - 1;
1769                                 continue;
1770                         }
1771                         if (opts < 0)
1772                                 exit(128);
1773                         continue;
1774                 }
1775
1776                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1777                         int j;
1778                         if (seen_dashdash || *arg == '^')
1779                                 die("bad revision '%s'", arg);
1780
1781                         /* If we didn't have a "--":
1782                          * (1) all filenames must exist;
1783                          * (2) all rev-args must not be interpretable
1784                          *     as a valid filename.
1785                          * but the latter we have checked in the main loop.
1786                          */
1787                         for (j = i; j < argc; j++)
1788                                 verify_filename(revs->prefix, argv[j], j == i);
1789
1790                         append_prune_data(&prune_data, argv + i);
1791                         break;
1792                 }
1793                 else
1794                         got_rev_arg = 1;
1795         }
1796
1797         if (prune_data.nr) {
1798                 /*
1799                  * If we need to introduce the magic "a lone ':' means no
1800                  * pathspec whatsoever", here is the place to do so.
1801                  *
1802                  * if (prune_data.nr == 1 && !strcmp(prune_data[0], ":")) {
1803                  *      prune_data.nr = 0;
1804                  *      prune_data.alloc = 0;
1805                  *      free(prune_data.path);
1806                  *      prune_data.path = NULL;
1807                  * } else {
1808                  *      terminate prune_data.alloc with NULL and
1809                  *      call init_pathspec() to set revs->prune_data here.
1810                  * }
1811                  */
1812                 ALLOC_GROW(prune_data.path, prune_data.nr+1, prune_data.alloc);
1813                 prune_data.path[prune_data.nr++] = NULL;
1814                 init_pathspec(&revs->prune_data,
1815                               get_pathspec(revs->prefix, prune_data.path));
1816         }
1817
1818         if (revs->def == NULL)
1819                 revs->def = opt ? opt->def : NULL;
1820         if (opt && opt->tweak)
1821                 opt->tweak(revs, opt);
1822         if (revs->show_merge)
1823                 prepare_show_merge(revs);
1824         if (revs->def && !revs->pending.nr && !got_rev_arg) {
1825                 unsigned char sha1[20];
1826                 struct object *object;
1827                 unsigned mode;
1828                 if (get_sha1_with_mode(revs->def, sha1, &mode))
1829                         die("bad default revision '%s'", revs->def);
1830                 object = get_reference(revs, revs->def, sha1, 0);
1831                 add_pending_object_with_mode(revs, object, revs->def, mode);
1832         }
1833
1834         /* Did the user ask for any diff output? Run the diff! */
1835         if (revs->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT)
1836                 revs->diff = 1;
1837
1838         /* Pickaxe, diff-filter and rename following need diffs */
1839         if (revs->diffopt.pickaxe ||
1840             revs->diffopt.filter ||
1841             DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
1842                 revs->diff = 1;
1843
1844         if (revs->topo_order)
1845                 revs->limited = 1;
1846
1847         if (revs->prune_data.nr) {
1848                 diff_tree_setup_paths(revs->prune_data.raw, &revs->pruning);
1849                 /* Can't prune commits with rename following: the paths change.. */
1850                 if (!DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
1851                         revs->prune = 1;
1852                 if (!revs->full_diff)
1853                         diff_tree_setup_paths(revs->prune_data.raw, &revs->diffopt);
1854         }
1855         if (revs->combine_merges)
1856                 revs->ignore_merges = 0;
1857         revs->diffopt.abbrev = revs->abbrev;
1858         diff_setup_done(&revs->diffopt);
1859
1860         compile_grep_patterns(&revs->grep_filter);
1861
1862         if (revs->reverse && revs->reflog_info)
1863                 die("cannot combine --reverse with --walk-reflogs");
1864         if (revs->rewrite_parents && revs->children.name)
1865                 die("cannot combine --parents and --children");
1866
1867         /*
1868          * Limitations on the graph functionality
1869          */
1870         if (revs->reverse && revs->graph)
1871                 die("cannot combine --reverse with --graph");
1872
1873         if (revs->reflog_info && revs->graph)
1874                 die("cannot combine --walk-reflogs with --graph");
1875
1876         return left;
1877 }
1878
1879 static void add_child(struct rev_info *revs, struct commit *parent, struct commit *child)
1880 {
1881         struct commit_list *l = xcalloc(1, sizeof(*l));
1882
1883         l->item = child;
1884         l->next = add_decoration(&revs->children, &parent->object, l);
1885 }
1886
1887 static int remove_duplicate_parents(struct commit *commit)
1888 {
1889         struct commit_list **pp, *p;
1890         int surviving_parents;
1891
1892         /* Examine existing parents while marking ones we have seen... */
1893         pp = &commit->parents;
1894         while ((p = *pp) != NULL) {
1895                 struct commit *parent = p->item;
1896                 if (parent->object.flags & TMP_MARK) {
1897                         *pp = p->next;
1898                         continue;
1899                 }
1900                 parent->object.flags |= TMP_MARK;
1901                 pp = &p->next;
1902         }
1903         /* count them while clearing the temporary mark */
1904         surviving_parents = 0;
1905         for (p = commit->parents; p; p = p->next) {
1906                 p->item->object.flags &= ~TMP_MARK;
1907                 surviving_parents++;
1908         }
1909         return surviving_parents;
1910 }
1911
1912 struct merge_simplify_state {
1913         struct commit *simplified;
1914 };
1915
1916 static struct merge_simplify_state *locate_simplify_state(struct rev_info *revs, struct commit *commit)
1917 {
1918         struct merge_simplify_state *st;
1919
1920         st = lookup_decoration(&revs->merge_simplification, &commit->object);
1921         if (!st) {
1922                 st = xcalloc(1, sizeof(*st));
1923                 add_decoration(&revs->merge_simplification, &commit->object, st);
1924         }
1925         return st;
1926 }
1927
1928 static struct commit_list **simplify_one(struct rev_info *revs, struct commit *commit, struct commit_list **tail)
1929 {
1930         struct commit_list *p;
1931         struct merge_simplify_state *st, *pst;
1932         int cnt;
1933
1934         st = locate_simplify_state(revs, commit);
1935
1936         /*
1937          * Have we handled this one?
1938          */
1939         if (st->simplified)
1940                 return tail;
1941
1942         /*
1943          * An UNINTERESTING commit simplifies to itself, so does a
1944          * root commit.  We do not rewrite parents of such commit
1945          * anyway.
1946          */
1947         if ((commit->object.flags & UNINTERESTING) || !commit->parents) {
1948                 st->simplified = commit;
1949                 return tail;
1950         }
1951
1952         /*
1953          * Do we know what commit all of our parents that matter
1954          * should be rewritten to?  Otherwise we are not ready to
1955          * rewrite this one yet.
1956          */
1957         for (cnt = 0, p = commit->parents; p; p = p->next) {
1958                 pst = locate_simplify_state(revs, p->item);
1959                 if (!pst->simplified) {
1960                         tail = &commit_list_insert(p->item, tail)->next;
1961                         cnt++;
1962                 }
1963                 if (revs->first_parent_only)
1964                         break;
1965         }
1966         if (cnt) {
1967                 tail = &commit_list_insert(commit, tail)->next;
1968                 return tail;
1969         }
1970
1971         /*
1972          * Rewrite our list of parents.
1973          */
1974         for (p = commit->parents; p; p = p->next) {
1975                 pst = locate_simplify_state(revs, p->item);
1976                 p->item = pst->simplified;
1977                 if (revs->first_parent_only)
1978                         break;
1979         }
1980         if (!revs->first_parent_only)
1981                 cnt = remove_duplicate_parents(commit);
1982         else
1983                 cnt = 1;
1984
1985         /*
1986          * It is possible that we are a merge and one side branch
1987          * does not have any commit that touches the given paths;
1988          * in such a case, the immediate parents will be rewritten
1989          * to different commits.
1990          *
1991          *      o----X          X: the commit we are looking at;
1992          *     /    /           o: a commit that touches the paths;
1993          * ---o----'
1994          *
1995          * Further reduce the parents by removing redundant parents.
1996          */
1997         if (1 < cnt) {
1998                 struct commit_list *h = reduce_heads(commit->parents);
1999                 cnt = commit_list_count(h);
2000                 free_commit_list(commit->parents);
2001                 commit->parents = h;
2002         }
2003
2004         /*
2005          * A commit simplifies to itself if it is a root, if it is
2006          * UNINTERESTING, if it touches the given paths, or if it is a
2007          * merge and its parents simplifies to more than one commits
2008          * (the first two cases are already handled at the beginning of
2009          * this function).
2010          *
2011          * Otherwise, it simplifies to what its sole parent simplifies to.
2012          */
2013         if (!cnt ||
2014             (commit->object.flags & UNINTERESTING) ||
2015             !(commit->object.flags & TREESAME) ||
2016             (1 < cnt))
2017                 st->simplified = commit;
2018         else {
2019                 pst = locate_simplify_state(revs, commit->parents->item);
2020                 st->simplified = pst->simplified;
2021         }
2022         return tail;
2023 }
2024
2025 static void simplify_merges(struct rev_info *revs)
2026 {
2027         struct commit_list *list, *next;
2028         struct commit_list *yet_to_do, **tail;
2029         struct commit *commit;
2030
2031         if (!revs->prune)
2032                 return;
2033
2034         /* feed the list reversed */
2035         yet_to_do = NULL;
2036         for (list = revs->commits; list; list = next) {
2037                 commit = list->item;
2038                 next = list->next;
2039                 /*
2040                  * Do not free(list) here yet; the original list
2041                  * is used later in this function.
2042                  */
2043                 commit_list_insert(commit, &yet_to_do);
2044         }
2045         while (yet_to_do) {
2046                 list = yet_to_do;
2047                 yet_to_do = NULL;
2048                 tail = &yet_to_do;
2049                 while (list) {
2050                         commit = list->item;
2051                         next = list->next;
2052                         free(list);
2053                         list = next;
2054                         tail = simplify_one(revs, commit, tail);
2055                 }
2056         }
2057
2058         /* clean up the result, removing the simplified ones */
2059         list = revs->commits;
2060         revs->commits = NULL;
2061         tail = &revs->commits;
2062         while (list) {
2063                 struct merge_simplify_state *st;
2064
2065                 commit = list->item;
2066                 next = list->next;
2067                 free(list);
2068                 list = next;
2069                 st = locate_simplify_state(revs, commit);
2070                 if (st->simplified == commit)
2071                         tail = &commit_list_insert(commit, tail)->next;
2072         }
2073 }
2074
2075 static void set_children(struct rev_info *revs)
2076 {
2077         struct commit_list *l;
2078         for (l = revs->commits; l; l = l->next) {
2079                 struct commit *commit = l->item;
2080                 struct commit_list *p;
2081
2082                 for (p = commit->parents; p; p = p->next)
2083                         add_child(revs, p->item, commit);
2084         }
2085 }
2086
2087 void reset_revision_walk(void)
2088 {
2089         clear_object_flags(SEEN | ADDED | SHOWN);
2090 }
2091
2092 int prepare_revision_walk(struct rev_info *revs)
2093 {
2094         int nr = revs->pending.nr;
2095         struct object_array_entry *e, *list;
2096         struct commit_list **next = &revs->commits;
2097
2098         e = list = revs->pending.objects;
2099         revs->pending.nr = 0;
2100         revs->pending.alloc = 0;
2101         revs->pending.objects = NULL;
2102         while (--nr >= 0) {
2103                 struct commit *commit = handle_commit(revs, e->item, e->name);
2104                 if (commit) {
2105                         if (!(commit->object.flags & SEEN)) {
2106                                 commit->object.flags |= SEEN;
2107                                 next = commit_list_append(commit, next);
2108                         }
2109                 }
2110                 e++;
2111         }
2112         commit_list_sort_by_date(&revs->commits);
2113         if (!revs->leak_pending)
2114                 free(list);
2115
2116         if (revs->no_walk)
2117                 return 0;
2118         if (revs->limited)
2119                 if (limit_list(revs) < 0)
2120                         return -1;
2121         if (revs->topo_order)
2122                 sort_in_topological_order(&revs->commits, revs->lifo);
2123         if (revs->simplify_merges)
2124                 simplify_merges(revs);
2125         if (revs->children.name)
2126                 set_children(revs);
2127         return 0;
2128 }
2129
2130 enum rewrite_result {
2131         rewrite_one_ok,
2132         rewrite_one_noparents,
2133         rewrite_one_error
2134 };
2135
2136 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
2137 {
2138         struct commit_list *cache = NULL;
2139
2140         for (;;) {
2141                 struct commit *p = *pp;
2142                 if (!revs->limited)
2143                         if (add_parents_to_list(revs, p, &revs->commits, &cache) < 0)
2144                                 return rewrite_one_error;
2145                 if (p->parents && p->parents->next)
2146                         return rewrite_one_ok;
2147                 if (p->object.flags & UNINTERESTING)
2148                         return rewrite_one_ok;
2149                 if (!(p->object.flags & TREESAME))
2150                         return rewrite_one_ok;
2151                 if (!p->parents)
2152                         return rewrite_one_noparents;
2153                 *pp = p->parents->item;
2154         }
2155 }
2156
2157 static int rewrite_parents(struct rev_info *revs, struct commit *commit)
2158 {
2159         struct commit_list **pp = &commit->parents;
2160         while (*pp) {
2161                 struct commit_list *parent = *pp;
2162                 switch (rewrite_one(revs, &parent->item)) {
2163                 case rewrite_one_ok:
2164                         break;
2165                 case rewrite_one_noparents:
2166                         *pp = parent->next;
2167                         continue;
2168                 case rewrite_one_error:
2169                         return -1;
2170                 }
2171                 pp = &parent->next;
2172         }
2173         remove_duplicate_parents(commit);
2174         return 0;
2175 }
2176
2177 static int commit_match(struct commit *commit, struct rev_info *opt)
2178 {
2179         if (!opt->grep_filter.pattern_list && !opt->grep_filter.header_list)
2180                 return 1;
2181         return grep_buffer(&opt->grep_filter,
2182                            commit->buffer, strlen(commit->buffer));
2183 }
2184
2185 static inline int want_ancestry(struct rev_info *revs)
2186 {
2187         return (revs->rewrite_parents || revs->children.name);
2188 }
2189
2190 enum commit_action get_commit_action(struct rev_info *revs, struct commit *commit)
2191 {
2192         if (commit->object.flags & SHOWN)
2193                 return commit_ignore;
2194         if (revs->unpacked && has_sha1_pack(commit->object.sha1))
2195                 return commit_ignore;
2196         if (revs->show_all)
2197                 return commit_show;
2198         if (commit->object.flags & UNINTERESTING)
2199                 return commit_ignore;
2200         if (revs->min_age != -1 && (commit->date > revs->min_age))
2201                 return commit_ignore;
2202         if (revs->min_parents || (revs->max_parents >= 0)) {
2203                 int n = 0;
2204                 struct commit_list *p;
2205                 for (p = commit->parents; p; p = p->next)
2206                         n++;
2207                 if ((n < revs->min_parents) ||
2208                     ((revs->max_parents >= 0) && (n > revs->max_parents)))
2209                         return commit_ignore;
2210         }
2211         if (!commit_match(commit, revs))
2212                 return commit_ignore;
2213         if (revs->prune && revs->dense) {
2214                 /* Commit without changes? */
2215                 if (commit->object.flags & TREESAME) {
2216                         /* drop merges unless we want parenthood */
2217                         if (!want_ancestry(revs))
2218                                 return commit_ignore;
2219                         /* non-merge - always ignore it */
2220                         if (!commit->parents || !commit->parents->next)
2221                                 return commit_ignore;
2222                 }
2223         }
2224         return commit_show;
2225 }
2226
2227 enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
2228 {
2229         enum commit_action action = get_commit_action(revs, commit);
2230
2231         if (action == commit_show &&
2232             !revs->show_all &&
2233             revs->prune && revs->dense && want_ancestry(revs)) {
2234                 if (rewrite_parents(revs, commit) < 0)
2235                         return commit_error;
2236         }
2237         return action;
2238 }
2239
2240 static struct commit *get_revision_1(struct rev_info *revs)
2241 {
2242         if (!revs->commits)
2243                 return NULL;
2244
2245         do {
2246                 struct commit_list *entry = revs->commits;
2247                 struct commit *commit = entry->item;
2248
2249                 revs->commits = entry->next;
2250                 free(entry);
2251
2252                 if (revs->reflog_info) {
2253                         fake_reflog_parent(revs->reflog_info, commit);
2254                         commit->object.flags &= ~(ADDED | SEEN | SHOWN);
2255                 }
2256
2257                 /*
2258                  * If we haven't done the list limiting, we need to look at
2259                  * the parents here. We also need to do the date-based limiting
2260                  * that we'd otherwise have done in limit_list().
2261                  */
2262                 if (!revs->limited) {
2263                         if (revs->max_age != -1 &&
2264                             (commit->date < revs->max_age))
2265                                 continue;
2266                         if (add_parents_to_list(revs, commit, &revs->commits, NULL) < 0)
2267                                 die("Failed to traverse parents of commit %s",
2268                                     sha1_to_hex(commit->object.sha1));
2269                 }
2270
2271                 switch (simplify_commit(revs, commit)) {
2272                 case commit_ignore:
2273                         continue;
2274                 case commit_error:
2275                         die("Failed to simplify parents of commit %s",
2276                             sha1_to_hex(commit->object.sha1));
2277                 default:
2278                         return commit;
2279                 }
2280         } while (revs->commits);
2281         return NULL;
2282 }
2283
2284 static void gc_boundary(struct object_array *array)
2285 {
2286         unsigned nr = array->nr;
2287         unsigned alloc = array->alloc;
2288         struct object_array_entry *objects = array->objects;
2289
2290         if (alloc <= nr) {
2291                 unsigned i, j;
2292                 for (i = j = 0; i < nr; i++) {
2293                         if (objects[i].item->flags & SHOWN)
2294                                 continue;
2295                         if (i != j)
2296                                 objects[j] = objects[i];
2297                         j++;
2298                 }
2299                 for (i = j; i < nr; i++)
2300                         objects[i].item = NULL;
2301                 array->nr = j;
2302         }
2303 }
2304
2305 static void create_boundary_commit_list(struct rev_info *revs)
2306 {
2307         unsigned i;
2308         struct commit *c;
2309         struct object_array *array = &revs->boundary_commits;
2310         struct object_array_entry *objects = array->objects;
2311
2312         /*
2313          * If revs->commits is non-NULL at this point, an error occurred in
2314          * get_revision_1().  Ignore the error and continue printing the
2315          * boundary commits anyway.  (This is what the code has always
2316          * done.)
2317          */
2318         if (revs->commits) {
2319                 free_commit_list(revs->commits);
2320                 revs->commits = NULL;
2321         }
2322
2323         /*
2324          * Put all of the actual boundary commits from revs->boundary_commits
2325          * into revs->commits
2326          */
2327         for (i = 0; i < array->nr; i++) {
2328                 c = (struct commit *)(objects[i].item);
2329                 if (!c)
2330                         continue;
2331                 if (!(c->object.flags & CHILD_SHOWN))
2332                         continue;
2333                 if (c->object.flags & (SHOWN | BOUNDARY))
2334                         continue;
2335                 c->object.flags |= BOUNDARY;
2336                 commit_list_insert(c, &revs->commits);
2337         }
2338
2339         /*
2340          * If revs->topo_order is set, sort the boundary commits
2341          * in topological order
2342          */
2343         sort_in_topological_order(&revs->commits, revs->lifo);
2344 }
2345
2346 static struct commit *get_revision_internal(struct rev_info *revs)
2347 {
2348         struct commit *c = NULL;
2349         struct commit_list *l;
2350
2351         if (revs->boundary == 2) {
2352                 /*
2353                  * All of the normal commits have already been returned,
2354                  * and we are now returning boundary commits.
2355                  * create_boundary_commit_list() has populated
2356                  * revs->commits with the remaining commits to return.
2357                  */
2358                 c = pop_commit(&revs->commits);
2359                 if (c)
2360                         c->object.flags |= SHOWN;
2361                 return c;
2362         }
2363
2364         /*
2365          * Now pick up what they want to give us
2366          */
2367         c = get_revision_1(revs);
2368         if (c) {
2369                 while (0 < revs->skip_count) {
2370                         revs->skip_count--;
2371                         c = get_revision_1(revs);
2372                         if (!c)
2373                                 break;
2374                 }
2375         }
2376
2377         /*
2378          * Check the max_count.
2379          */
2380         switch (revs->max_count) {
2381         case -1:
2382                 break;
2383         case 0:
2384                 c = NULL;
2385                 break;
2386         default:
2387                 revs->max_count--;
2388         }
2389
2390         if (c)
2391                 c->object.flags |= SHOWN;
2392
2393         if (!revs->boundary) {
2394                 return c;
2395         }
2396
2397         if (!c) {
2398                 /*
2399                  * get_revision_1() runs out the commits, and
2400                  * we are done computing the boundaries.
2401                  * switch to boundary commits output mode.
2402                  */
2403                 revs->boundary = 2;
2404
2405                 /*
2406                  * Update revs->commits to contain the list of
2407                  * boundary commits.
2408                  */
2409                 create_boundary_commit_list(revs);
2410
2411                 return get_revision_internal(revs);
2412         }
2413
2414         /*
2415          * boundary commits are the commits that are parents of the
2416          * ones we got from get_revision_1() but they themselves are
2417          * not returned from get_revision_1().  Before returning
2418          * 'c', we need to mark its parents that they could be boundaries.
2419          */
2420
2421         for (l = c->parents; l; l = l->next) {
2422                 struct object *p;
2423                 p = &(l->item->object);
2424                 if (p->flags & (CHILD_SHOWN | SHOWN))
2425                         continue;
2426                 p->flags |= CHILD_SHOWN;
2427                 gc_boundary(&revs->boundary_commits);
2428                 add_object_array(p, NULL, &revs->boundary_commits);
2429         }
2430
2431         return c;
2432 }
2433
2434 struct commit *get_revision(struct rev_info *revs)
2435 {
2436         struct commit *c;
2437         struct commit_list *reversed;
2438
2439         if (revs->reverse) {
2440                 reversed = NULL;
2441                 while ((c = get_revision_internal(revs))) {
2442                         commit_list_insert(c, &reversed);
2443                 }
2444                 revs->commits = reversed;
2445                 revs->reverse = 0;
2446                 revs->reverse_output_stage = 1;
2447         }
2448
2449         if (revs->reverse_output_stage)
2450                 return pop_commit(&revs->commits);
2451
2452         c = get_revision_internal(revs);
2453         if (c && revs->graph)
2454                 graph_update(revs->graph, c);
2455         return c;
2456 }
2457
2458 char *get_revision_mark(const struct rev_info *revs, const struct commit *commit)
2459 {
2460         if (commit->object.flags & BOUNDARY)
2461                 return "-";
2462         else if (commit->object.flags & UNINTERESTING)
2463                 return "^";
2464         else if (commit->object.flags & PATCHSAME)
2465                 return "=";
2466         else if (!revs || revs->left_right) {
2467                 if (commit->object.flags & SYMMETRIC_LEFT)
2468                         return "<";
2469                 else
2470                         return ">";
2471         } else if (revs->graph)
2472                 return "*";
2473         else if (revs->cherry_mark)
2474                 return "+";
2475         return "";
2476 }
2477
2478 void put_revision_mark(const struct rev_info *revs, const struct commit *commit)
2479 {
2480         char *mark = get_revision_mark(revs, commit);
2481         if (!strlen(mark))
2482                 return;
2483         fputs(mark, stdout);
2484         putchar(' ');
2485 }