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