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
  15 volatile show_early_output_fn_t show_early_output;
  16
  17 static char *path_name(struct name_path *path, const char *name)
  18 {
  19         struct name_path *p;
  20         char *n, *m;
  21         int nlen = strlen(name);
  22         int len = nlen + 1;
  23
  24         for (p = path; p; p = p->up) {
  25                 if (p->elem_len)
  26                         len += p->elem_len + 1;
  27         }
  28         n = xmalloc(len);
  29         m = n + len - (nlen + 1);
  30         strcpy(m, name);
  31         for (p = path; p; p = p->up) {
  32                 if (p->elem_len) {
  33                         m -= p->elem_len + 1;
  34                         memcpy(m, p->elem, p->elem_len);
  35                         m[p->elem_len] = '/';
  36                 }
  37         }
  38         return n;
  39 }
  40
  41 void add_object(struct object *obj,
  42                 struct object_array *p,
  43                 struct name_path *path,
  44                 const char *name)
  45 {
  46         add_object_array(obj, path_name(path, name), p);
  47 }
  48
  49 static void mark_blob_uninteresting(struct blob *blob)
  50 {
  51         if (!blob)
  52                 return;
  53         if (blob->object.flags & UNINTERESTING)
  54                 return;
  55         blob->object.flags |= UNINTERESTING;
  56 }
  57
  58 void mark_tree_uninteresting(struct tree *tree)
  59 {
  60         struct tree_desc desc;
  61         struct name_entry entry;
  62         struct object *obj = &tree->object;
  63
  64         if (!tree)
  65                 return;
  66         if (obj->flags & UNINTERESTING)
  67                 return;
  68         obj->flags |= UNINTERESTING;
  69         if (!has_sha1_file(obj->sha1))
  70                 return;
  71         if (parse_tree(tree) < 0)
  72                 die("bad tree %s", sha1_to_hex(obj->sha1));
  73
  74         init_tree_desc(&desc, tree->buffer, tree->size);
  75         while (tree_entry(&desc, &entry)) {
  76                 switch (object_type(entry.mode)) {
  77                 case OBJ_TREE:
  78                         mark_tree_uninteresting(lookup_tree(entry.sha1));
  79                         break;
  80                 case OBJ_BLOB:
  81                         mark_blob_uninteresting(lookup_blob(entry.sha1));
  82                         break;
  83                 default:
  84                         /* Subproject commit - not in this repository */
  85                         break;
  86                 }
  87         }
  88
  89         /*
  90          * We don't care about the tree any more
  91          * after it has been marked uninteresting.
  92          */
  93         free(tree->buffer);
  94         tree->buffer = NULL;
  95 }
  96
  97 void mark_parents_uninteresting(struct commit *commit)
  98 {
  99         struct commit_list *parents = commit->parents;
 100
 101         while (parents) {
 102                 struct commit *commit = parents->item;
 103                 if (!(commit->object.flags & UNINTERESTING)) {
 104                         commit->object.flags |= UNINTERESTING;
 105
 106                         /*
 107                          * Normally we haven't parsed the parent
 108                          * yet, so we won't have a parent of a parent
 109                          * here. However, it may turn out that we've
 110                          * reached this commit some other way (where it
 111                          * wasn't uninteresting), in which case we need
 112                          * to mark its parents recursively too..
 113                          */
 114                         if (commit->parents)
 115                                 mark_parents_uninteresting(commit);
 116                 }
 117
 118                 /*
 119                  * A missing commit is ok iff its parent is marked
 120                  * uninteresting.
 121                  *
 122                  * We just mark such a thing parsed, so that when
 123                  * it is popped next time around, we won't be trying
 124                  * to parse it and get an error.
 125                  */
 126                 if (!has_sha1_file(commit->object.sha1))
 127                         commit->object.parsed = 1;
 128                 parents = parents->next;
 129         }
 130 }
 131
 132 static void add_pending_object_with_mode(struct rev_info *revs, struct object *obj, const char *name, unsigned mode)
 133 {
 134         if (revs->no_walk && (obj->flags & UNINTERESTING))
 135                 die("object ranges do not make sense when not walking revisions");
 136         if (revs->reflog_info && obj->type == OBJ_COMMIT &&
 137                         add_reflog_for_walk(revs->reflog_info,
 138                                 (struct commit *)obj, name))
 139                 return;
 140         add_object_array_with_mode(obj, name, &revs->pending, mode);
 141 }
 142
 143 void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
 144 {
 145         add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
 146 }
 147
 148 void add_head_to_pending(struct rev_info *revs)
 149 {
 150         unsigned char sha1[20];
 151         struct object *obj;
 152         if (get_sha1("HEAD", sha1))
 153                 return;
 154         obj = parse_object(sha1);
 155         if (!obj)
 156                 return;
 157         add_pending_object(revs, obj, "HEAD");
 158 }
 159
 160 static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
 161 {
 162         struct object *object;
 163
 164         object = parse_object(sha1);
 165         if (!object)
 166                 die("bad object %s", name);
 167         object->flags |= flags;
 168         return object;
 169 }
 170
 171 static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
 172 {
 173         unsigned long flags = object->flags;
 174
 175         /*
 176          * Tag object? Look what it points to..
 177          */
 178         while (object->type == OBJ_TAG) {
 179                 struct tag *tag = (struct tag *) object;
 180                 if (revs->tag_objects && !(flags & UNINTERESTING))
 181                         add_pending_object(revs, object, tag->tag);
 182                 if (!tag->tagged)
 183                         die("bad tag");
 184                 object = parse_object(tag->tagged->sha1);
 185                 if (!object)
 186                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
 187         }
 188
 189         /*
 190          * Commit object? Just return it, we'll do all the complex
 191          * reachability crud.
 192          */
 193         if (object->type == OBJ_COMMIT) {
 194                 struct commit *commit = (struct commit *)object;
 195                 if (parse_commit(commit) < 0)
 196                         die("unable to parse commit %s", name);
 197                 if (flags & UNINTERESTING) {
 198                         commit->object.flags |= UNINTERESTING;
 199                         mark_parents_uninteresting(commit);
 200                         revs->limited = 1;
 201                 }
 202                 return commit;
 203         }
 204
 205         /*
 206          * Tree object? Either mark it uniniteresting, or add it
 207          * to the list of objects to look at later..
 208          */
 209         if (object->type == OBJ_TREE) {
 210                 struct tree *tree = (struct tree *)object;
 211                 if (!revs->tree_objects)
 212                         return NULL;
 213                 if (flags & UNINTERESTING) {
 214                         mark_tree_uninteresting(tree);
 215                         return NULL;
 216                 }
 217                 add_pending_object(revs, object, "");
 218                 return NULL;
 219         }
 220
 221         /*
 222          * Blob object? You know the drill by now..
 223          */
 224         if (object->type == OBJ_BLOB) {
 225                 struct blob *blob = (struct blob *)object;
 226                 if (!revs->blob_objects)
 227                         return NULL;
 228                 if (flags & UNINTERESTING) {
 229                         mark_blob_uninteresting(blob);
 230                         return NULL;
 231                 }
 232                 add_pending_object(revs, object, "");
 233                 return NULL;
 234         }
 235         die("%s is unknown object", name);
 236 }
 237
 238 static int everybody_uninteresting(struct commit_list *orig)
 239 {
 240         struct commit_list *list = orig;
 241         while (list) {
 242                 struct commit *commit = list->item;
 243                 list = list->next;
 244                 if (commit->object.flags & UNINTERESTING)
 245                         continue;
 246                 return 0;
 247         }
 248         return 1;
 249 }
 250
 251 /*
 252  * The goal is to get REV_TREE_NEW as the result only if the
 253  * diff consists of all '+' (and no other changes), and
 254  * REV_TREE_DIFFERENT otherwise (of course if the trees are
 255  * the same we want REV_TREE_SAME).  That means that once we
 256  * get to REV_TREE_DIFFERENT, we do not have to look any further.
 257  */
 258 static int tree_difference = REV_TREE_SAME;
 259
 260 static void file_add_remove(struct diff_options *options,
 261                     int addremove, unsigned mode,
 262                     const unsigned char *sha1,
 263                     const char *base, const char *path)
 264 {
 265         int diff = REV_TREE_DIFFERENT;
 266
 267         /*
 268          * Is it an add of a new file? It means that the old tree
 269          * didn't have it at all, so we will turn "REV_TREE_SAME" ->
 270          * "REV_TREE_NEW", but leave any "REV_TREE_DIFFERENT" alone
 271          * (and if it already was "REV_TREE_NEW", we'll keep it
 272          * "REV_TREE_NEW" of course).
 273          */
 274         if (addremove == '+') {
 275                 diff = tree_difference;
 276                 if (diff != REV_TREE_SAME)
 277                         return;
 278                 diff = REV_TREE_NEW;
 279         }
 280         tree_difference = diff;
 281         if (tree_difference == REV_TREE_DIFFERENT)
 282                 DIFF_OPT_SET(options, HAS_CHANGES);
 283 }
 284
 285 static void file_change(struct diff_options *options,
 286                  unsigned old_mode, unsigned new_mode,
 287                  const unsigned char *old_sha1,
 288                  const unsigned char *new_sha1,
 289                  const char *base, const char *path)
 290 {
 291         tree_difference = REV_TREE_DIFFERENT;
 292         DIFF_OPT_SET(options, HAS_CHANGES);
 293 }
 294
 295 static int rev_compare_tree(struct rev_info *revs, struct tree *t1, struct tree *t2)
 296 {
 297         if (!t1)
 298                 return REV_TREE_NEW;
 299         if (!t2)
 300                 return REV_TREE_DIFFERENT;
 301         tree_difference = REV_TREE_SAME;
 302         DIFF_OPT_CLR(&revs->pruning, HAS_CHANGES);
 303         if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "",
 304                            &revs->pruning) < 0)
 305                 return REV_TREE_DIFFERENT;
 306         return tree_difference;
 307 }
 308
 309 static int rev_same_tree_as_empty(struct rev_info *revs, struct tree *t1)
 310 {
 311         int retval;
 312         void *tree;
 313         unsigned long size;
 314         struct tree_desc empty, real;
 315
 316         if (!t1)
 317                 return 0;
 318
 319         tree = read_object_with_reference(t1->object.sha1, tree_type, &size, NULL);
 320         if (!tree)
 321                 return 0;
 322         init_tree_desc(&real, tree, size);
 323         init_tree_desc(&empty, "", 0);
 324
 325         tree_difference = REV_TREE_SAME;
 326         DIFF_OPT_CLR(&revs->pruning, HAS_CHANGES);
 327         retval = diff_tree(&empty, &real, "", &revs->pruning);
 328         free(tree);
 329
 330         return retval >= 0 && (tree_difference == REV_TREE_SAME);
 331 }
 332
 333 static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
 334 {
 335         struct commit_list **pp, *parent;
 336         int tree_changed = 0, tree_same = 0;
 337
 338         /*
 339          * If we don't do pruning, everything is interesting
 340          */
 341         if (!revs->prune)
 342                 return;
 343
 344         if (!commit->tree)
 345                 return;
 346
 347         if (!commit->parents) {
 348                 if (rev_same_tree_as_empty(revs, commit->tree))
 349                         commit->object.flags |= TREESAME;
 350                 return;
 351         }
 352
 353         /*
 354          * Normal non-merge commit? If we don't want to make the
 355          * history dense, we consider it always to be a change..
 356          */
 357         if (!revs->dense && !commit->parents->next)
 358                 return;
 359
 360         pp = &commit->parents;
 361         while ((parent = *pp) != NULL) {
 362                 struct commit *p = parent->item;
 363
 364                 if (parse_commit(p) < 0)
 365                         die("cannot simplify commit %s (because of %s)",
 366                             sha1_to_hex(commit->object.sha1),
 367                             sha1_to_hex(p->object.sha1));
 368                 switch (rev_compare_tree(revs, p->tree, commit->tree)) {
 369                 case REV_TREE_SAME:
 370                         tree_same = 1;
 371                         if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
 372                                 /* Even if a merge with an uninteresting
 373                                  * side branch brought the entire change
 374                                  * we are interested in, we do not want
 375                                  * to lose the other branches of this
 376                                  * merge, so we just keep going.
 377                                  */
 378                                 pp = &parent->next;
 379                                 continue;
 380                         }
 381                         parent->next = NULL;
 382                         commit->parents = parent;
 383                         commit->object.flags |= TREESAME;
 384                         return;
 385
 386                 case REV_TREE_NEW:
 387                         if (revs->remove_empty_trees &&
 388                             rev_same_tree_as_empty(revs, p->tree)) {
 389                                 /* We are adding all the specified
 390                                  * paths from this parent, so the
 391                                  * history beyond this parent is not
 392                                  * interesting.  Remove its parents
 393                                  * (they are grandparents for us).
 394                                  * IOW, we pretend this parent is a
 395                                  * "root" commit.
 396                                  */
 397                                 if (parse_commit(p) < 0)
 398                                         die("cannot simplify commit %s (invalid %s)",
 399                                             sha1_to_hex(commit->object.sha1),
 400                                             sha1_to_hex(p->object.sha1));
 401                                 p->parents = NULL;
 402                         }
 403                 /* fallthrough */
 404                 case REV_TREE_DIFFERENT:
 405                         tree_changed = 1;
 406                         pp = &parent->next;
 407                         continue;
 408                 }
 409                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 410         }
 411         if (tree_changed && !tree_same)
 412                 return;
 413         commit->object.flags |= TREESAME;
 414 }
 415
 416 static int add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 417 {
 418         struct commit_list *parent = commit->parents;
 419         unsigned left_flag;
 420
 421         if (commit->object.flags & ADDED)
 422                 return 0;
 423         commit->object.flags |= ADDED;
 424
 425         /*
 426          * If the commit is uninteresting, don't try to
 427          * prune parents - we want the maximal uninteresting
 428          * set.
 429          *
 430          * Normally we haven't parsed the parent
 431          * yet, so we won't have a parent of a parent
 432          * here. However, it may turn out that we've
 433          * reached this commit some other way (where it
 434          * wasn't uninteresting), in which case we need
 435          * to mark its parents recursively too..
 436          */
 437         if (commit->object.flags & UNINTERESTING) {
 438                 while (parent) {
 439                         struct commit *p = parent->item;
 440                         parent = parent->next;
 441                         if (parse_commit(p) < 0)
 442                                 return -1;
 443                         p->object.flags |= UNINTERESTING;
 444                         if (p->parents)
 445                                 mark_parents_uninteresting(p);
 446                         if (p->object.flags & SEEN)
 447                                 continue;
 448                         p->object.flags |= SEEN;
 449                         insert_by_date(p, list);
 450                 }
 451                 return 0;
 452         }
 453
 454         /*
 455          * Ok, the commit wasn't uninteresting. Try to
 456          * simplify the commit history and find the parent
 457          * that has no differences in the path set if one exists.
 458          */
 459         try_to_simplify_commit(revs, commit);
 460
 461         if (revs->no_walk)
 462                 return 0;
 463
 464         left_flag = (commit->object.flags & SYMMETRIC_LEFT);
 465
 466         for (parent = commit->parents; parent; parent = parent->next) {
 467                 struct commit *p = parent->item;
 468
 469                 if (parse_commit(p) < 0)
 470                         return -1;
 471                 p->object.flags |= left_flag;
 472                 if (!(p->object.flags & SEEN)) {
 473                         p->object.flags |= SEEN;
 474                         insert_by_date(p, list);
 475                 }
 476                 if(revs->first_parent_only)
 477                         break;
 478         }
 479         return 0;
 480 }
 481
 482 static void cherry_pick_list(struct commit_list *list, struct rev_info *revs)
 483 {
 484         struct commit_list *p;
 485         int left_count = 0, right_count = 0;
 486         int left_first;
 487         struct patch_ids ids;
 488
 489         /* First count the commits on the left and on the right */
 490         for (p = list; p; p = p->next) {
 491                 struct commit *commit = p->item;
 492                 unsigned flags = commit->object.flags;
 493                 if (flags & BOUNDARY)
 494                         ;
 495                 else if (flags & SYMMETRIC_LEFT)
 496                         left_count++;
 497                 else
 498                         right_count++;
 499         }
 500
 501         left_first = left_count < right_count;
 502         init_patch_ids(&ids);
 503         if (revs->diffopt.nr_paths) {
 504                 ids.diffopts.nr_paths = revs->diffopt.nr_paths;
 505                 ids.diffopts.paths = revs->diffopt.paths;
 506                 ids.diffopts.pathlens = revs->diffopt.pathlens;
 507         }
 508
 509         /* Compute patch-ids for one side */
 510         for (p = list; p; p = p->next) {
 511                 struct commit *commit = p->item;
 512                 unsigned flags = commit->object.flags;
 513
 514                 if (flags & BOUNDARY)
 515                         continue;
 516                 /*
 517                  * If we have fewer left, left_first is set and we omit
 518                  * commits on the right branch in this loop.  If we have
 519                  * fewer right, we skip the left ones.
 520                  */
 521                 if (left_first != !!(flags & SYMMETRIC_LEFT))
 522                         continue;
 523                 commit->util = add_commit_patch_id(commit, &ids);
 524         }
 525
 526         /* Check the other side */
 527         for (p = list; p; p = p->next) {
 528                 struct commit *commit = p->item;
 529                 struct patch_id *id;
 530                 unsigned flags = commit->object.flags;
 531
 532                 if (flags & BOUNDARY)
 533                         continue;
 534                 /*
 535                  * If we have fewer left, left_first is set and we omit
 536                  * commits on the left branch in this loop.
 537                  */
 538                 if (left_first == !!(flags & SYMMETRIC_LEFT))
 539                         continue;
 540
 541                 /*
 542                  * Have we seen the same patch id?
 543                  */
 544                 id = has_commit_patch_id(commit, &ids);
 545                 if (!id)
 546                         continue;
 547                 id->seen = 1;
 548                 commit->object.flags |= SHOWN;
 549         }
 550
 551         /* Now check the original side for seen ones */
 552         for (p = list; p; p = p->next) {
 553                 struct commit *commit = p->item;
 554                 struct patch_id *ent;
 555
 556                 ent = commit->util;
 557                 if (!ent)
 558                         continue;
 559                 if (ent->seen)
 560                         commit->object.flags |= SHOWN;
 561                 commit->util = NULL;
 562         }
 563
 564         free_patch_ids(&ids);
 565 }
 566
 567 /* How many extra uninteresting commits we want to see.. */
 568 #define SLOP 5
 569
 570 static int still_interesting(struct commit_list *src, unsigned long date, int slop)
 571 {
 572         /*
 573          * No source list at all? We're definitely done..
 574          */
 575         if (!src)
 576                 return 0;
 577
 578         /*
 579          * Does the destination list contain entries with a date
 580          * before the source list? Definitely _not_ done.
 581          */
 582         if (date < src->item->date)
 583                 return SLOP;
 584
 585         /*
 586          * Does the source list still have interesting commits in
 587          * it? Definitely not done..
 588          */
 589         if (!everybody_uninteresting(src))
 590                 return SLOP;
 591
 592         /* Ok, we're closing in.. */
 593         return slop-1;
 594 }
 595
 596 static int limit_list(struct rev_info *revs)
 597 {
 598         int slop = SLOP;
 599         unsigned long date = ~0ul;
 600         struct commit_list *list = revs->commits;
 601         struct commit_list *newlist = NULL;
 602         struct commit_list **p = &newlist;
 603
 604         while (list) {
 605                 struct commit_list *entry = list;
 606                 struct commit *commit = list->item;
 607                 struct object *obj = &commit->object;
 608                 show_early_output_fn_t show;
 609
 610                 list = list->next;
 611                 free(entry);
 612
 613                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 614                         obj->flags |= UNINTERESTING;
 615                 if (add_parents_to_list(revs, commit, &list) < 0)
 616                         return -1;
 617                 if (obj->flags & UNINTERESTING) {
 618                         mark_parents_uninteresting(commit);
 619                         if (revs->show_all)
 620                                 p = &commit_list_insert(commit, p)->next;
 621                         slop = still_interesting(list, date, slop);
 622                         if (slop)
 623                                 continue;
 624                         /* If showing all, add the whole pending list to the end */
 625                         if (revs->show_all)
 626                                 *p = list;
 627                         break;
 628                 }
 629                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 630                         continue;
 631                 date = commit->date;
 632                 p = &commit_list_insert(commit, p)->next;
 633
 634                 show = show_early_output;
 635                 if (!show)
 636                         continue;
 637
 638                 show(revs, newlist);
 639                 show_early_output = NULL;
 640         }
 641         if (revs->cherry_pick)
 642                 cherry_pick_list(newlist, revs);
 643
 644         revs->commits = newlist;
 645         return 0;
 646 }
 647
 648 struct all_refs_cb {
 649         int all_flags;
 650         int warned_bad_reflog;
 651         struct rev_info *all_revs;
 652         const char *name_for_errormsg;
 653 };
 654
 655 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 656 {
 657         struct all_refs_cb *cb = cb_data;
 658         struct object *object = get_reference(cb->all_revs, path, sha1,
 659                                               cb->all_flags);
 660         add_pending_object(cb->all_revs, object, path);
 661         return 0;
 662 }
 663
 664 static void handle_refs(struct rev_info *revs, unsigned flags,
 665                 int (*for_each)(each_ref_fn, void *))
 666 {
 667         struct all_refs_cb cb;
 668         cb.all_revs = revs;
 669         cb.all_flags = flags;
 670         for_each(handle_one_ref, &cb);
 671 }
 672
 673 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 674 {
 675         struct all_refs_cb *cb = cb_data;
 676         if (!is_null_sha1(sha1)) {
 677                 struct object *o = parse_object(sha1);
 678                 if (o) {
 679                         o->flags |= cb->all_flags;
 680                         add_pending_object(cb->all_revs, o, "");
 681                 }
 682                 else if (!cb->warned_bad_reflog) {
 683                         warning("reflog of '%s' references pruned commits",
 684                                 cb->name_for_errormsg);
 685                         cb->warned_bad_reflog = 1;
 686                 }
 687         }
 688 }
 689
 690 static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 691                 const char *email, unsigned long timestamp, int tz,
 692                 const char *message, void *cb_data)
 693 {
 694         handle_one_reflog_commit(osha1, cb_data);
 695         handle_one_reflog_commit(nsha1, cb_data);
 696         return 0;
 697 }
 698
 699 static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 700 {
 701         struct all_refs_cb *cb = cb_data;
 702         cb->warned_bad_reflog = 0;
 703         cb->name_for_errormsg = path;
 704         for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
 705         return 0;
 706 }
 707
 708 static void handle_reflog(struct rev_info *revs, unsigned flags)
 709 {
 710         struct all_refs_cb cb;
 711         cb.all_revs = revs;
 712         cb.all_flags = flags;
 713         for_each_reflog(handle_one_reflog, &cb);
 714 }
 715
 716 static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 717 {
 718         unsigned char sha1[20];
 719         struct object *it;
 720         struct commit *commit;
 721         struct commit_list *parents;
 722
 723         if (*arg == '^') {
 724                 flags ^= UNINTERESTING;
 725                 arg++;
 726         }
 727         if (get_sha1(arg, sha1))
 728                 return 0;
 729         while (1) {
 730                 it = get_reference(revs, arg, sha1, 0);
 731                 if (it->type != OBJ_TAG)
 732                         break;
 733                 if (!((struct tag*)it)->tagged)
 734                         return 0;
 735                 hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
 736         }
 737         if (it->type != OBJ_COMMIT)
 738                 return 0;
 739         commit = (struct commit *)it;
 740         for (parents = commit->parents; parents; parents = parents->next) {
 741                 it = &parents->item->object;
 742                 it->flags |= flags;
 743                 add_pending_object(revs, it, arg);
 744         }
 745         return 1;
 746 }
 747
 748 void init_revisions(struct rev_info *revs, const char *prefix)
 749 {
 750         memset(revs, 0, sizeof(*revs));
 751
 752         revs->abbrev = DEFAULT_ABBREV;
 753         revs->ignore_merges = 1;
 754         revs->simplify_history = 1;
 755         DIFF_OPT_SET(&revs->pruning, RECURSIVE);
 756         DIFF_OPT_SET(&revs->pruning, QUIET);
 757         revs->pruning.add_remove = file_add_remove;
 758         revs->pruning.change = file_change;
 759         revs->lifo = 1;
 760         revs->dense = 1;
 761         revs->prefix = prefix;
 762         revs->max_age = -1;
 763         revs->min_age = -1;
 764         revs->skip_count = -1;
 765         revs->max_count = -1;
 766
 767         revs->commit_format = CMIT_FMT_DEFAULT;
 768
 769         diff_setup(&revs->diffopt);
 770         if (prefix && !revs->diffopt.prefix) {
 771                 revs->diffopt.prefix = prefix;
 772                 revs->diffopt.prefix_length = strlen(prefix);
 773         }
 774 }
 775
 776 static void add_pending_commit_list(struct rev_info *revs,
 777                                     struct commit_list *commit_list,
 778                                     unsigned int flags)
 779 {
 780         while (commit_list) {
 781                 struct object *object = &commit_list->item->object;
 782                 object->flags |= flags;
 783                 add_pending_object(revs, object, sha1_to_hex(object->sha1));
 784                 commit_list = commit_list->next;
 785         }
 786 }
 787
 788 static void prepare_show_merge(struct rev_info *revs)
 789 {
 790         struct commit_list *bases;
 791         struct commit *head, *other;
 792         unsigned char sha1[20];
 793         const char **prune = NULL;
 794         int i, prune_num = 1; /* counting terminating NULL */
 795
 796         if (get_sha1("HEAD", sha1) || !(head = lookup_commit(sha1)))
 797                 die("--merge without HEAD?");
 798         if (get_sha1("MERGE_HEAD", sha1) || !(other = lookup_commit(sha1)))
 799                 die("--merge without MERGE_HEAD?");
 800         add_pending_object(revs, &head->object, "HEAD");
 801         add_pending_object(revs, &other->object, "MERGE_HEAD");
 802         bases = get_merge_bases(head, other, 1);
 803         add_pending_commit_list(revs, bases, UNINTERESTING);
 804         free_commit_list(bases);
 805         head->object.flags |= SYMMETRIC_LEFT;
 806
 807         if (!active_nr)
 808                 read_cache();
 809         for (i = 0; i < active_nr; i++) {
 810                 struct cache_entry *ce = active_cache[i];
 811                 if (!ce_stage(ce))
 812                         continue;
 813                 if (ce_path_match(ce, revs->prune_data)) {
 814                         prune_num++;
 815                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
 816                         prune[prune_num-2] = ce->name;
 817                         prune[prune_num-1] = NULL;
 818                 }
 819                 while ((i+1 < active_nr) &&
 820                        ce_same_name(ce, active_cache[i+1]))
 821                         i++;
 822         }
 823         revs->prune_data = prune;
 824         revs->limited = 1;
 825 }
 826
 827 int handle_revision_arg(const char *arg, struct rev_info *revs,
 828                         int flags,
 829                         int cant_be_filename)
 830 {
 831         unsigned mode;
 832         char *dotdot;
 833         struct object *object;
 834         unsigned char sha1[20];
 835         int local_flags;
 836
 837         dotdot = strstr(arg, "..");
 838         if (dotdot) {
 839                 unsigned char from_sha1[20];
 840                 const char *next = dotdot + 2;
 841                 const char *this = arg;
 842                 int symmetric = *next == '.';
 843                 unsigned int flags_exclude = flags ^ UNINTERESTING;
 844
 845                 *dotdot = 0;
 846                 next += symmetric;
 847
 848                 if (!*next)
 849                         next = "HEAD";
 850                 if (dotdot == arg)
 851                         this = "HEAD";
 852                 if (!get_sha1(this, from_sha1) &&
 853                     !get_sha1(next, sha1)) {
 854                         struct commit *a, *b;
 855                         struct commit_list *exclude;
 856
 857                         a = lookup_commit_reference(from_sha1);
 858                         b = lookup_commit_reference(sha1);
 859                         if (!a || !b) {
 860                                 die(symmetric ?
 861                                     "Invalid symmetric difference expression %s...%s" :
 862                                     "Invalid revision range %s..%s",
 863                                     arg, next);
 864                         }
 865
 866                         if (!cant_be_filename) {
 867                                 *dotdot = '.';
 868                                 verify_non_filename(revs->prefix, arg);
 869                         }
 870
 871                         if (symmetric) {
 872                                 exclude = get_merge_bases(a, b, 1);
 873                                 add_pending_commit_list(revs, exclude,
 874                                                         flags_exclude);
 875                                 free_commit_list(exclude);
 876                                 a->object.flags |= flags | SYMMETRIC_LEFT;
 877                         } else
 878                                 a->object.flags |= flags_exclude;
 879                         b->object.flags |= flags;
 880                         add_pending_object(revs, &a->object, this);
 881                         add_pending_object(revs, &b->object, next);
 882                         return 0;
 883                 }
 884                 *dotdot = '.';
 885         }
 886         dotdot = strstr(arg, "^@");
 887         if (dotdot && !dotdot[2]) {
 888                 *dotdot = 0;
 889                 if (add_parents_only(revs, arg, flags))
 890                         return 0;
 891                 *dotdot = '^';
 892         }
 893         dotdot = strstr(arg, "^!");
 894         if (dotdot && !dotdot[2]) {
 895                 *dotdot = 0;
 896                 if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
 897                         *dotdot = '^';
 898         }
 899
 900         local_flags = 0;
 901         if (*arg == '^') {
 902                 local_flags = UNINTERESTING;
 903                 arg++;
 904         }
 905         if (get_sha1_with_mode(arg, sha1, &mode))
 906                 return -1;
 907         if (!cant_be_filename)
 908                 verify_non_filename(revs->prefix, arg);
 909         object = get_reference(revs, arg, sha1, flags ^ local_flags);
 910         add_pending_object_with_mode(revs, object, arg, mode);
 911         return 0;
 912 }
 913
 914 static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
 915 {
 916         if (!revs->grep_filter) {
 917                 struct grep_opt *opt = xcalloc(1, sizeof(*opt));
 918                 opt->status_only = 1;
 919                 opt->pattern_tail = &(opt->pattern_list);
 920                 opt->regflags = REG_NEWLINE;
 921                 revs->grep_filter = opt;
 922         }
 923         append_grep_pattern(revs->grep_filter, ptn,
 924                             "command line", 0, what);
 925 }
 926
 927 static void add_header_grep(struct rev_info *revs, const char *field, const char *pattern)
 928 {
 929         char *pat;
 930         const char *prefix;
 931         int patlen, fldlen;
 932
 933         fldlen = strlen(field);
 934         patlen = strlen(pattern);
 935         pat = xmalloc(patlen + fldlen + 10);
 936         prefix = ".*";
 937         if (*pattern == '^') {
 938                 prefix = "";
 939                 pattern++;
 940         }
 941         sprintf(pat, "^%s %s%s", field, prefix, pattern);
 942         add_grep(revs, pat, GREP_PATTERN_HEAD);
 943 }
 944
 945 static void add_message_grep(struct rev_info *revs, const char *pattern)
 946 {
 947         add_grep(revs, pattern, GREP_PATTERN_BODY);
 948 }
 949
 950 static void add_ignore_packed(struct rev_info *revs, const char *name)
 951 {
 952         int num = ++revs->num_ignore_packed;
 953
 954         revs->ignore_packed = xrealloc(revs->ignore_packed,
 955                                        sizeof(const char **) * (num + 1));
 956         revs->ignore_packed[num-1] = name;
 957         revs->ignore_packed[num] = NULL;
 958 }
 959
 960 int handle_revision_opt(struct rev_info *revs, int argc, const char **argv,
 961                         int *unkc, const char **unkv)
 962 {
 963         const char *arg = argv[0];
 964
 965         /* pseudo revision arguments */
 966         if (!strcmp(arg, "--all") || !strcmp(arg, "--branches") ||
 967             !strcmp(arg, "--tags") || !strcmp(arg, "--remotes") ||
 968             !strcmp(arg, "--reflog") || !strcmp(arg, "--not") ||
 969             !strcmp(arg, "--no-walk") || !strcmp(arg, "--do-walk"))
 970         {
 971                 unkv[(*unkc)++] = arg;
 972                 return 0;
 973         }
 974
 975         if (!prefixcmp(arg, "--max-count=")) {
 976                 revs->max_count = atoi(arg + 12);
 977         } else if (!prefixcmp(arg, "--skip=")) {
 978                 revs->skip_count = atoi(arg + 7);
 979         } else if ((*arg == '-') && isdigit(arg[1])) {
 980         /* accept -<digit>, like traditional "head" */
 981                 revs->max_count = atoi(arg + 1);
 982         } else if (!strcmp(arg, "-n")) {
 983                 if (argc <= 1)
 984                         return error("-n requires an argument");
 985                 revs->max_count = atoi(argv[1]);
 986                 return 2;
 987         } else if (!prefixcmp(arg, "-n")) {
 988                 revs->max_count = atoi(arg + 2);
 989         } else if (!prefixcmp(arg, "--max-age=")) {
 990                 revs->max_age = atoi(arg + 10);
 991         } else if (!prefixcmp(arg, "--since=")) {
 992                 revs->max_age = approxidate(arg + 8);
 993         } else if (!prefixcmp(arg, "--after=")) {
 994                 revs->max_age = approxidate(arg + 8);
 995         } else if (!prefixcmp(arg, "--min-age=")) {
 996                 revs->min_age = atoi(arg + 10);
 997         } else if (!prefixcmp(arg, "--before=")) {
 998                 revs->min_age = approxidate(arg + 9);
 999         } else if (!prefixcmp(arg, "--until=")) {
1000                 revs->min_age = approxidate(arg + 8);
1001         } else if (!strcmp(arg, "--first-parent")) {
1002                 revs->first_parent_only = 1;
1003         } else if (!strcmp(arg, "-g") || !strcmp(arg, "--walk-reflogs")) {
1004                 init_reflog_walk(&revs->reflog_info);
1005         } else if (!strcmp(arg, "--default")) {
1006                 if (argc <= 1)
1007                         return error("bad --default argument");
1008                 revs->def = argv[1];
1009                 return 2;
1010         } else if (!strcmp(arg, "--merge")) {
1011                 revs->show_merge = 1;
1012         } else if (!strcmp(arg, "--topo-order")) {
1013                 revs->lifo = 1;
1014                 revs->topo_order = 1;
1015         } else if (!strcmp(arg, "--date-order")) {
1016                 revs->lifo = 0;
1017                 revs->topo_order = 1;
1018         } else if (!prefixcmp(arg, "--early-output")) {
1019                 int count = 100;
1020                 switch (arg[14]) {
1021                 case '=':
1022                         count = atoi(arg+15);
1023                         /* Fallthrough */
1024                 case 0:
1025                         revs->topo_order = 1;
1026                        revs->early_output = count;
1027                 }
1028         } else if (!strcmp(arg, "--parents")) {
1029                 revs->rewrite_parents = 1;
1030                 revs->print_parents = 1;
1031         } else if (!strcmp(arg, "--dense")) {
1032                 revs->dense = 1;
1033         } else if (!strcmp(arg, "--sparse")) {
1034                 revs->dense = 0;
1035         } else if (!strcmp(arg, "--show-all")) {
1036                 revs->show_all = 1;
1037         } else if (!strcmp(arg, "--remove-empty")) {
1038                 revs->remove_empty_trees = 1;
1039         } else if (!strcmp(arg, "--no-merges")) {
1040                 revs->no_merges = 1;
1041         } else if (!strcmp(arg, "--boundary")) {
1042                 revs->boundary = 1;
1043         } else if (!strcmp(arg, "--left-right")) {
1044                 revs->left_right = 1;
1045         } else if (!strcmp(arg, "--cherry-pick")) {
1046                 revs->cherry_pick = 1;
1047                 revs->limited = 1;
1048         } else if (!strcmp(arg, "--objects")) {
1049                 revs->tag_objects = 1;
1050                 revs->tree_objects = 1;
1051                 revs->blob_objects = 1;
1052         } else if (!strcmp(arg, "--objects-edge")) {
1053                 revs->tag_objects = 1;
1054                 revs->tree_objects = 1;
1055                 revs->blob_objects = 1;
1056                 revs->edge_hint = 1;
1057         } else if (!strcmp(arg, "--unpacked")) {
1058                 revs->unpacked = 1;
1059                 free(revs->ignore_packed);
1060                 revs->ignore_packed = NULL;
1061                 revs->num_ignore_packed = 0;
1062         } else if (!prefixcmp(arg, "--unpacked=")) {
1063                 revs->unpacked = 1;
1064                 add_ignore_packed(revs, arg+11);
1065         } else if (!strcmp(arg, "-r")) {
1066                 revs->diff = 1;
1067                 DIFF_OPT_SET(&revs->diffopt, RECURSIVE);
1068         } else if (!strcmp(arg, "-t")) {
1069                 revs->diff = 1;
1070                 DIFF_OPT_SET(&revs->diffopt, RECURSIVE);
1071                 DIFF_OPT_SET(&revs->diffopt, TREE_IN_RECURSIVE);
1072         } else if (!strcmp(arg, "-m")) {
1073                 revs->ignore_merges = 0;
1074         } else if (!strcmp(arg, "-c")) {
1075                 revs->diff = 1;
1076                 revs->dense_combined_merges = 0;
1077                 revs->combine_merges = 1;
1078         } else if (!strcmp(arg, "--cc")) {
1079                 revs->diff = 1;
1080                 revs->dense_combined_merges = 1;
1081                 revs->combine_merges = 1;
1082         } else if (!strcmp(arg, "-v")) {
1083                 revs->verbose_header = 1;
1084         } else if (!strcmp(arg, "--pretty")) {
1085                 revs->verbose_header = 1;
1086                 get_commit_format(arg+8, revs);
1087         } else if (!prefixcmp(arg, "--pretty=")) {
1088                 revs->verbose_header = 1;
1089                 get_commit_format(arg+9, revs);
1090         } else if (!strcmp(arg, "--graph")) {
1091                 revs->topo_order = 1;
1092                 revs->rewrite_parents = 1;
1093                 revs->graph = graph_init(revs);
1094         } else if (!strcmp(arg, "--root")) {
1095                 revs->show_root_diff = 1;
1096         } else if (!strcmp(arg, "--no-commit-id")) {
1097                 revs->no_commit_id = 1;
1098         } else if (!strcmp(arg, "--always")) {
1099                 revs->always_show_header = 1;
1100         } else if (!strcmp(arg, "--no-abbrev")) {
1101                 revs->abbrev = 0;
1102         } else if (!strcmp(arg, "--abbrev")) {
1103                 revs->abbrev = DEFAULT_ABBREV;
1104         } else if (!prefixcmp(arg, "--abbrev=")) {
1105                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1106                 if (revs->abbrev < MINIMUM_ABBREV)
1107                         revs->abbrev = MINIMUM_ABBREV;
1108                 else if (revs->abbrev > 40)
1109                         revs->abbrev = 40;
1110         } else if (!strcmp(arg, "--abbrev-commit")) {
1111                 revs->abbrev_commit = 1;
1112         } else if (!strcmp(arg, "--full-diff")) {
1113                 revs->diff = 1;
1114                 revs->full_diff = 1;
1115         } else if (!strcmp(arg, "--full-history")) {
1116                 revs->simplify_history = 0;
1117         } else if (!strcmp(arg, "--relative-date")) {
1118                 revs->date_mode = DATE_RELATIVE;
1119         } else if (!strncmp(arg, "--date=", 7)) {
1120                 revs->date_mode = parse_date_format(arg + 7);
1121         } else if (!strcmp(arg, "--log-size")) {
1122                 revs->show_log_size = 1;
1123         }
1124         /*
1125          * Grepping the commit log
1126          */
1127         else if (!prefixcmp(arg, "--author=")) {
1128                 add_header_grep(revs, "author", arg+9);
1129         } else if (!prefixcmp(arg, "--committer=")) {
1130                 add_header_grep(revs, "committer", arg+12);
1131         } else if (!prefixcmp(arg, "--grep=")) {
1132                 add_message_grep(revs, arg+7);
1133         } else if (!strcmp(arg, "--extended-regexp") || !strcmp(arg, "-E")) {
1134                 if (revs->grep_filter)
1135                         revs->grep_filter->regflags |= REG_EXTENDED;
1136         } else if (!strcmp(arg, "--regexp-ignore-case") || !strcmp(arg, "-i")) {
1137                 if (revs->grep_filter)
1138                         revs->grep_filter->regflags |= REG_ICASE;
1139         } else if (!strcmp(arg, "--fixed-strings") || !strcmp(arg, "-F")) {
1140                 if (revs->grep_filter)
1141                         revs->grep_filter->fixed = 1;
1142         } else if (!strcmp(arg, "--all-match")) {
1143                 if (revs->grep_filter)
1144                         revs->grep_filter->all_match = 1;
1145         } else if (!prefixcmp(arg, "--encoding=")) {
1146                 arg += 11;
1147                 if (strcmp(arg, "none"))
1148                         git_log_output_encoding = xstrdup(arg);
1149                 else
1150                         git_log_output_encoding = "";
1151         } else if (!strcmp(arg, "--reverse")) {
1152                 revs->reverse ^= 1;
1153         } else if (!strcmp(arg, "--children")) {
1154                 revs->children.name = "children";
1155                 revs->limited = 1;
1156         } else {
1157                 int opts = diff_opt_parse(&revs->diffopt, argv, argc);
1158                 if (!opts)
1159                         unkv[(*unkc)++] = arg;
1160                 return opts;
1161         }
1162
1163         return 1;
1164 }
1165
1166 /*
1167  * Parse revision information, filling in the "rev_info" structure,
1168  * and removing the used arguments from the argument list.
1169  *
1170  * Returns the number of arguments left that weren't recognized
1171  * (which are also moved to the head of the argument list)
1172  */
1173 int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
1174 {
1175         int i, flags, left, seen_dashdash;
1176
1177         /* First, search for "--" */
1178         seen_dashdash = 0;
1179         for (i = 1; i < argc; i++) {
1180                 const char *arg = argv[i];
1181                 if (strcmp(arg, "--"))
1182                         continue;
1183                 argv[i] = NULL;
1184                 argc = i;
1185                 if (argv[i + 1])
1186                         revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
1187                 seen_dashdash = 1;
1188                 break;
1189         }
1190
1191         /* Second, deal with arguments and options */
1192         flags = 0;
1193         for (left = i = 1; i < argc; i++) {
1194                 const char *arg = argv[i];
1195                 if (*arg == '-') {
1196                         int opts;
1197
1198                         if (!strcmp(arg, "--all")) {
1199                                 handle_refs(revs, flags, for_each_ref);
1200                                 continue;
1201                         }
1202                         if (!strcmp(arg, "--branches")) {
1203                                 handle_refs(revs, flags, for_each_branch_ref);
1204                                 continue;
1205                         }
1206                         if (!strcmp(arg, "--tags")) {
1207                                 handle_refs(revs, flags, for_each_tag_ref);
1208                                 continue;
1209                         }
1210                         if (!strcmp(arg, "--remotes")) {
1211                                 handle_refs(revs, flags, for_each_remote_ref);
1212                                 continue;
1213                         }
1214                         if (!strcmp(arg, "--reflog")) {
1215                                 handle_reflog(revs, flags);
1216                                 continue;
1217                         }
1218                         if (!strcmp(arg, "--not")) {
1219                                 flags ^= UNINTERESTING;
1220                                 continue;
1221                         }
1222                         if (!strcmp(arg, "--no-walk")) {
1223                                 revs->no_walk = 1;
1224                                 continue;
1225                         }
1226                         if (!strcmp(arg, "--do-walk")) {
1227                                 revs->no_walk = 0;
1228                                 continue;
1229                         }
1230
1231                         opts = handle_revision_opt(revs, argc - i, argv + i, &left, argv);
1232                         if (opts > 0) {
1233                                 i += opts - 1;
1234                                 continue;
1235                         }
1236                         if (opts < 0)
1237                                 exit(128);
1238                         continue;
1239                 }
1240
1241                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1242                         int j;
1243                         if (seen_dashdash || *arg == '^')
1244                                 die("bad revision '%s'", arg);
1245
1246                         /* If we didn't have a "--":
1247                          * (1) all filenames must exist;
1248                          * (2) all rev-args must not be interpretable
1249                          *     as a valid filename.
1250                          * but the latter we have checked in the main loop.
1251                          */
1252                         for (j = i; j < argc; j++)
1253                                 verify_filename(revs->prefix, argv[j]);
1254
1255                         revs->prune_data = get_pathspec(revs->prefix,
1256                                                         argv + i);
1257                         break;
1258                 }
1259         }
1260
1261         if (revs->def == NULL)
1262                 revs->def = def;
1263         if (revs->show_merge)
1264                 prepare_show_merge(revs);
1265         if (revs->def && !revs->pending.nr) {
1266                 unsigned char sha1[20];
1267                 struct object *object;
1268                 unsigned mode;
1269                 if (get_sha1_with_mode(revs->def, sha1, &mode))
1270                         die("bad default revision '%s'", revs->def);
1271                 object = get_reference(revs, revs->def, sha1, 0);
1272                 add_pending_object_with_mode(revs, object, revs->def, mode);
1273         }
1274
1275         /* Did the user ask for any diff output? Run the diff! */
1276         if (revs->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT)
1277                 revs->diff = 1;
1278
1279         /* Pickaxe, diff-filter and rename following need diffs */
1280         if (revs->diffopt.pickaxe ||
1281             revs->diffopt.filter ||
1282             DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
1283                 revs->diff = 1;
1284
1285         if (revs->topo_order)
1286                 revs->limited = 1;
1287
1288         if (revs->prune_data) {
1289                 diff_tree_setup_paths(revs->prune_data, &revs->pruning);
1290                 /* Can't prune commits with rename following: the paths change.. */
1291                 if (!DIFF_OPT_TST(&revs->diffopt, FOLLOW_RENAMES))
1292                         revs->prune = 1;
1293                 if (!revs->full_diff)
1294                         diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
1295         }
1296         if (revs->combine_merges) {
1297                 revs->ignore_merges = 0;
1298                 if (revs->dense_combined_merges && !revs->diffopt.output_format)
1299                         revs->diffopt.output_format = DIFF_FORMAT_PATCH;
1300         }
1301         revs->diffopt.abbrev = revs->abbrev;
1302         if (diff_setup_done(&revs->diffopt) < 0)
1303                 die("diff_setup_done failed");
1304
1305         if (revs->grep_filter) {
1306                 compile_grep_patterns(revs->grep_filter);
1307         }
1308
1309         if (revs->reverse && revs->reflog_info)
1310                 die("cannot combine --reverse with --walk-reflogs");
1311         if (revs->rewrite_parents && revs->children.name)
1312                 die("cannot combine --parents and --children");
1313
1314         /*
1315          * Limitations on the graph functionality
1316          */
1317         if (revs->reverse && revs->graph)
1318                 die("cannot combine --reverse with --graph");
1319
1320         if (revs->reflog_info && revs->graph)
1321                 die("cannot combine --walk-reflogs with --graph");
1322
1323         return left;
1324 }
1325
1326 static void add_child(struct rev_info *revs, struct commit *parent, struct commit *child)
1327 {
1328         struct commit_list *l = xcalloc(1, sizeof(*l));
1329
1330         l->item = child;
1331         l->next = add_decoration(&revs->children, &parent->object, l);
1332 }
1333
1334 static void set_children(struct rev_info *revs)
1335 {
1336         struct commit_list *l;
1337         for (l = revs->commits; l; l = l->next) {
1338                 struct commit *commit = l->item;
1339                 struct commit_list *p;
1340
1341                 for (p = commit->parents; p; p = p->next)
1342                         add_child(revs, p->item, commit);
1343         }
1344 }
1345
1346 int prepare_revision_walk(struct rev_info *revs)
1347 {
1348         int nr = revs->pending.nr;
1349         struct object_array_entry *e, *list;
1350
1351         e = list = revs->pending.objects;
1352         revs->pending.nr = 0;
1353         revs->pending.alloc = 0;
1354         revs->pending.objects = NULL;
1355         while (--nr >= 0) {
1356                 struct commit *commit = handle_commit(revs, e->item, e->name);
1357                 if (commit) {
1358                         if (!(commit->object.flags & SEEN)) {
1359                                 commit->object.flags |= SEEN;
1360                                 insert_by_date(commit, &revs->commits);
1361                         }
1362                 }
1363                 e++;
1364         }
1365         free(list);
1366
1367         if (revs->no_walk)
1368                 return 0;
1369         if (revs->limited)
1370                 if (limit_list(revs) < 0)
1371                         return -1;
1372         if (revs->topo_order)
1373                 sort_in_topological_order(&revs->commits, revs->lifo);
1374         if (revs->children.name)
1375                 set_children(revs);
1376         return 0;
1377 }
1378
1379 enum rewrite_result {
1380         rewrite_one_ok,
1381         rewrite_one_noparents,
1382         rewrite_one_error,
1383 };
1384
1385 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
1386 {
1387         for (;;) {
1388                 struct commit *p = *pp;
1389                 if (!revs->limited)
1390                         if (add_parents_to_list(revs, p, &revs->commits) < 0)
1391                                 return rewrite_one_error;
1392                 if (p->parents && p->parents->next)
1393                         return rewrite_one_ok;
1394                 if (p->object.flags & UNINTERESTING)
1395                         return rewrite_one_ok;
1396                 if (!(p->object.flags & TREESAME))
1397                         return rewrite_one_ok;
1398                 if (!p->parents)
1399                         return rewrite_one_noparents;
1400                 *pp = p->parents->item;
1401         }
1402 }
1403
1404 static void remove_duplicate_parents(struct commit *commit)
1405 {
1406         struct commit_list **pp, *p;
1407
1408         /* Examine existing parents while marking ones we have seen... */
1409         pp = &commit->parents;
1410         while ((p = *pp) != NULL) {
1411                 struct commit *parent = p->item;
1412                 if (parent->object.flags & TMP_MARK) {
1413                         *pp = p->next;
1414                         continue;
1415                 }
1416                 parent->object.flags |= TMP_MARK;
1417                 pp = &p->next;
1418         }
1419         /* ... and clear the temporary mark */
1420         for (p = commit->parents; p; p = p->next)
1421                 p->item->object.flags &= ~TMP_MARK;
1422 }
1423
1424 static int rewrite_parents(struct rev_info *revs, struct commit *commit)
1425 {
1426         struct commit_list **pp = &commit->parents;
1427         while (*pp) {
1428                 struct commit_list *parent = *pp;
1429                 switch (rewrite_one(revs, &parent->item)) {
1430                 case rewrite_one_ok:
1431                         break;
1432                 case rewrite_one_noparents:
1433                         *pp = parent->next;
1434                         continue;
1435                 case rewrite_one_error:
1436                         return -1;
1437                 }
1438                 pp = &parent->next;
1439         }
1440         remove_duplicate_parents(commit);
1441         return 0;
1442 }
1443
1444 static int commit_match(struct commit *commit, struct rev_info *opt)
1445 {
1446         if (!opt->grep_filter)
1447                 return 1;
1448         return grep_buffer(opt->grep_filter,
1449                            NULL, /* we say nothing, not even filename */
1450                            commit->buffer, strlen(commit->buffer));
1451 }
1452
1453 static inline int want_ancestry(struct rev_info *revs)
1454 {
1455         return (revs->rewrite_parents || revs->children.name);
1456 }
1457
1458 enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit)
1459 {
1460         if (commit->object.flags & SHOWN)
1461                 return commit_ignore;
1462         if (revs->unpacked && has_sha1_pack(commit->object.sha1, revs->ignore_packed))
1463                 return commit_ignore;
1464         if (revs->show_all)
1465                 return commit_show;
1466         if (commit->object.flags & UNINTERESTING)
1467                 return commit_ignore;
1468         if (revs->min_age != -1 && (commit->date > revs->min_age))
1469                 return commit_ignore;
1470         if (revs->no_merges && commit->parents && commit->parents->next)
1471                 return commit_ignore;
1472         if (!commit_match(commit, revs))
1473                 return commit_ignore;
1474         if (revs->prune && revs->dense) {
1475                 /* Commit without changes? */
1476                 if (commit->object.flags & TREESAME) {
1477                         /* drop merges unless we want parenthood */
1478                         if (!want_ancestry(revs))
1479                                 return commit_ignore;
1480                         /* non-merge - always ignore it */
1481                         if (!commit->parents || !commit->parents->next)
1482                                 return commit_ignore;
1483                 }
1484                 if (want_ancestry(revs) && rewrite_parents(revs, commit) < 0)
1485                         return commit_error;
1486         }
1487         return commit_show;
1488 }
1489
1490 static struct commit *get_revision_1(struct rev_info *revs)
1491 {
1492         if (!revs->commits)
1493                 return NULL;
1494
1495         do {
1496                 struct commit_list *entry = revs->commits;
1497                 struct commit *commit = entry->item;
1498
1499                 revs->commits = entry->next;
1500                 free(entry);
1501
1502                 if (revs->reflog_info)
1503                         fake_reflog_parent(revs->reflog_info, commit);
1504
1505                 /*
1506                  * If we haven't done the list limiting, we need to look at
1507                  * the parents here. We also need to do the date-based limiting
1508                  * that we'd otherwise have done in limit_list().
1509                  */
1510                 if (!revs->limited) {
1511                         if (revs->max_age != -1 &&
1512                             (commit->date < revs->max_age))
1513                                 continue;
1514                         if (add_parents_to_list(revs, commit, &revs->commits) < 0)
1515                                 return NULL;
1516                 }
1517
1518                 switch (simplify_commit(revs, commit)) {
1519                 case commit_ignore:
1520                         continue;
1521                 case commit_error:
1522                         return NULL;
1523                 default:
1524                         return commit;
1525                 }
1526         } while (revs->commits);
1527         return NULL;
1528 }
1529
1530 static void gc_boundary(struct object_array *array)
1531 {
1532         unsigned nr = array->nr;
1533         unsigned alloc = array->alloc;
1534         struct object_array_entry *objects = array->objects;
1535
1536         if (alloc <= nr) {
1537                 unsigned i, j;
1538                 for (i = j = 0; i < nr; i++) {
1539                         if (objects[i].item->flags & SHOWN)
1540                                 continue;
1541                         if (i != j)
1542                                 objects[j] = objects[i];
1543                         j++;
1544                 }
1545                 for (i = j; i < nr; i++)
1546                         objects[i].item = NULL;
1547                 array->nr = j;
1548         }
1549 }
1550
1551 static void create_boundary_commit_list(struct rev_info *revs)
1552 {
1553         unsigned i;
1554         struct commit *c;
1555         struct object_array *array = &revs->boundary_commits;
1556         struct object_array_entry *objects = array->objects;
1557
1558         /*
1559          * If revs->commits is non-NULL at this point, an error occurred in
1560          * get_revision_1().  Ignore the error and continue printing the
1561          * boundary commits anyway.  (This is what the code has always
1562          * done.)
1563          */
1564         if (revs->commits) {
1565                 free_commit_list(revs->commits);
1566                 revs->commits = NULL;
1567         }
1568
1569         /*
1570          * Put all of the actual boundary commits from revs->boundary_commits
1571          * into revs->commits
1572          */
1573         for (i = 0; i < array->nr; i++) {
1574                 c = (struct commit *)(objects[i].item);
1575                 if (!c)
1576                         continue;
1577                 if (!(c->object.flags & CHILD_SHOWN))
1578                         continue;
1579                 if (c->object.flags & (SHOWN | BOUNDARY))
1580                         continue;
1581                 c->object.flags |= BOUNDARY;
1582                 commit_list_insert(c, &revs->commits);
1583         }
1584
1585         /*
1586          * If revs->topo_order is set, sort the boundary commits
1587          * in topological order
1588          */
1589         sort_in_topological_order(&revs->commits, revs->lifo);
1590 }
1591
1592 static struct commit *get_revision_internal(struct rev_info *revs)
1593 {
1594         struct commit *c = NULL;
1595         struct commit_list *l;
1596
1597         if (revs->boundary == 2) {
1598                 /*
1599                  * All of the normal commits have already been returned,
1600                  * and we are now returning boundary commits.
1601                  * create_boundary_commit_list() has populated
1602                  * revs->commits with the remaining commits to return.
1603                  */
1604                 c = pop_commit(&revs->commits);
1605                 if (c)
1606                         c->object.flags |= SHOWN;
1607                 return c;
1608         }
1609
1610         if (revs->reverse) {
1611                 int limit = -1;
1612
1613                 if (0 <= revs->max_count) {
1614                         limit = revs->max_count;
1615                         if (0 < revs->skip_count)
1616                                 limit += revs->skip_count;
1617                 }
1618                 l = NULL;
1619                 while ((c = get_revision_1(revs))) {
1620                         commit_list_insert(c, &l);
1621                         if ((0 < limit) && !--limit)
1622                                 break;
1623                 }
1624                 revs->commits = l;
1625                 revs->reverse = 0;
1626                 revs->max_count = -1;
1627                 c = NULL;
1628         }
1629
1630         /*
1631          * Now pick up what they want to give us
1632          */
1633         c = get_revision_1(revs);
1634         if (c) {
1635                 while (0 < revs->skip_count) {
1636                         revs->skip_count--;
1637                         c = get_revision_1(revs);
1638                         if (!c)
1639                                 break;
1640                 }
1641         }
1642
1643         /*
1644          * Check the max_count.
1645          */
1646         switch (revs->max_count) {
1647         case -1:
1648                 break;
1649         case 0:
1650                 c = NULL;
1651                 break;
1652         default:
1653                 revs->max_count--;
1654         }
1655
1656         if (c)
1657                 c->object.flags |= SHOWN;
1658
1659         if (!revs->boundary) {
1660                 return c;
1661         }
1662
1663         if (!c) {
1664                 /*
1665                  * get_revision_1() runs out the commits, and
1666                  * we are done computing the boundaries.
1667                  * switch to boundary commits output mode.
1668                  */
1669                 revs->boundary = 2;
1670
1671                 /*
1672                  * Update revs->commits to contain the list of
1673                  * boundary commits.
1674                  */
1675                 create_boundary_commit_list(revs);
1676
1677                 return get_revision_internal(revs);
1678         }
1679
1680         /*
1681          * boundary commits are the commits that are parents of the
1682          * ones we got from get_revision_1() but they themselves are
1683          * not returned from get_revision_1().  Before returning
1684          * 'c', we need to mark its parents that they could be boundaries.
1685          */
1686
1687         for (l = c->parents; l; l = l->next) {
1688                 struct object *p;
1689                 p = &(l->item->object);
1690                 if (p->flags & (CHILD_SHOWN | SHOWN))
1691                         continue;
1692                 p->flags |= CHILD_SHOWN;
1693                 gc_boundary(&revs->boundary_commits);
1694                 add_object_array(p, NULL, &revs->boundary_commits);
1695         }
1696
1697         return c;
1698 }
1699
1700 struct commit *get_revision(struct rev_info *revs)
1701 {
1702         struct commit *c = get_revision_internal(revs);
1703         if (c && revs->graph)
1704                 graph_update(revs->graph, c);
1705         return c;
1706 }