revision.c

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