revision.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "blob.h"
   4 #include "tree.h"
   5 #include "commit.h"
   6 #include "diff.h"
   7 #include "refs.h"
   8 #include "revision.h"
   9 #include "grep.h"
  10 #include "reflog-walk.h"
  11 #include "patch-ids.h"
  12
  13 static char *path_name(struct name_path *path, const char *name)
  14 {
  15         struct name_path *p;
  16         char *n, *m;
  17         int nlen = strlen(name);
  18         int len = nlen + 1;
  19
  20         for (p = path; p; p = p->up) {
  21                 if (p->elem_len)
  22                         len += p->elem_len + 1;
  23         }
  24         n = xmalloc(len);
  25         m = n + len - (nlen + 1);
  26         strcpy(m, name);
  27         for (p = path; p; p = p->up) {
  28                 if (p->elem_len) {
  29                         m -= p->elem_len + 1;
  30                         memcpy(m, p->elem, p->elem_len);
  31                         m[p->elem_len] = '/';
  32                 }
  33         }
  34         return n;
  35 }
  36
  37 void add_object(struct object *obj,
  38                 struct object_array *p,
  39                 struct name_path *path,
  40                 const char *name)
  41 {
  42         add_object_array(obj, path_name(path, name), p);
  43 }
  44
  45 static void mark_blob_uninteresting(struct blob *blob)
  46 {
  47         if (blob->object.flags & UNINTERESTING)
  48                 return;
  49         blob->object.flags |= UNINTERESTING;
  50 }
  51
  52 void mark_tree_uninteresting(struct tree *tree)
  53 {
  54         struct tree_desc desc;
  55         struct name_entry entry;
  56         struct object *obj = &tree->object;
  57
  58         if (obj->flags & UNINTERESTING)
  59                 return;
  60         obj->flags |= UNINTERESTING;
  61         if (!has_sha1_file(obj->sha1))
  62                 return;
  63         if (parse_tree(tree) < 0)
  64                 die("bad tree %s", sha1_to_hex(obj->sha1));
  65
  66         init_tree_desc(&desc, tree->buffer, tree->size);
  67         while (tree_entry(&desc, &entry)) {
  68                 switch (object_type(entry.mode)) {
  69                 case OBJ_TREE:
  70                         mark_tree_uninteresting(lookup_tree(entry.sha1));
  71                         break;
  72                 case OBJ_BLOB:
  73                         mark_blob_uninteresting(lookup_blob(entry.sha1));
  74                         break;
  75                 default:
  76                         /* Subproject commit - not in this repository */
  77                         break;
  78                 }
  79         }
  80
  81         /*
  82          * We don't care about the tree any more
  83          * after it has been marked uninteresting.
  84          */
  85         free(tree->buffer);
  86         tree->buffer = NULL;
  87 }
  88
  89 void mark_parents_uninteresting(struct commit *commit)
  90 {
  91         struct commit_list *parents = commit->parents;
  92
  93         while (parents) {
  94                 struct commit *commit = parents->item;
  95                 if (!(commit->object.flags & UNINTERESTING)) {
  96                         commit->object.flags |= UNINTERESTING;
  97
  98                         /*
  99                          * Normally we haven't parsed the parent
 100                          * yet, so we won't have a parent of a parent
 101                          * here. However, it may turn out that we've
 102                          * reached this commit some other way (where it
 103                          * wasn't uninteresting), in which case we need
 104                          * to mark its parents recursively too..
 105                          */
 106                         if (commit->parents)
 107                                 mark_parents_uninteresting(commit);
 108                 }
 109
 110                 /*
 111                  * A missing commit is ok iff its parent is marked
 112                  * uninteresting.
 113                  *
 114                  * We just mark such a thing parsed, so that when
 115                  * it is popped next time around, we won't be trying
 116                  * to parse it and get an error.
 117                  */
 118                 if (!has_sha1_file(commit->object.sha1))
 119                         commit->object.parsed = 1;
 120                 parents = parents->next;
 121         }
 122 }
 123
 124 static void add_pending_object_with_mode(struct rev_info *revs, struct object *obj, const char *name, unsigned mode)
 125 {
 126         if (revs->no_walk && (obj->flags & UNINTERESTING))
 127                 die("object ranges do not make sense when not walking revisions");
 128         if (revs->reflog_info && obj->type == OBJ_COMMIT &&
 129                         add_reflog_for_walk(revs->reflog_info,
 130                                 (struct commit *)obj, name))
 131                 return;
 132         add_object_array_with_mode(obj, name, &revs->pending, mode);
 133 }
 134
 135 void add_pending_object(struct rev_info *revs, struct object *obj, const char *name)
 136 {
 137         add_pending_object_with_mode(revs, obj, name, S_IFINVALID);
 138 }
 139
 140 static struct object *get_reference(struct rev_info *revs, const char *name, const unsigned char *sha1, unsigned int flags)
 141 {
 142         struct object *object;
 143
 144         object = parse_object(sha1);
 145         if (!object)
 146                 die("bad object %s", name);
 147         object->flags |= flags;
 148         return object;
 149 }
 150
 151 static struct commit *handle_commit(struct rev_info *revs, struct object *object, const char *name)
 152 {
 153         unsigned long flags = object->flags;
 154
 155         /*
 156          * Tag object? Look what it points to..
 157          */
 158         while (object->type == OBJ_TAG) {
 159                 struct tag *tag = (struct tag *) object;
 160                 if (revs->tag_objects && !(flags & UNINTERESTING))
 161                         add_pending_object(revs, object, tag->tag);
 162                 object = parse_object(tag->tagged->sha1);
 163                 if (!object)
 164                         die("bad object %s", sha1_to_hex(tag->tagged->sha1));
 165         }
 166
 167         /*
 168          * Commit object? Just return it, we'll do all the complex
 169          * reachability crud.
 170          */
 171         if (object->type == OBJ_COMMIT) {
 172                 struct commit *commit = (struct commit *)object;
 173                 if (parse_commit(commit) < 0)
 174                         die("unable to parse commit %s", name);
 175                 if (flags & UNINTERESTING) {
 176                         commit->object.flags |= UNINTERESTING;
 177                         mark_parents_uninteresting(commit);
 178                         revs->limited = 1;
 179                 }
 180                 return commit;
 181         }
 182
 183         /*
 184          * Tree object? Either mark it uniniteresting, or add it
 185          * to the list of objects to look at later..
 186          */
 187         if (object->type == OBJ_TREE) {
 188                 struct tree *tree = (struct tree *)object;
 189                 if (!revs->tree_objects)
 190                         return NULL;
 191                 if (flags & UNINTERESTING) {
 192                         mark_tree_uninteresting(tree);
 193                         return NULL;
 194                 }
 195                 add_pending_object(revs, object, "");
 196                 return NULL;
 197         }
 198
 199         /*
 200          * Blob object? You know the drill by now..
 201          */
 202         if (object->type == OBJ_BLOB) {
 203                 struct blob *blob = (struct blob *)object;
 204                 if (!revs->blob_objects)
 205                         return NULL;
 206                 if (flags & UNINTERESTING) {
 207                         mark_blob_uninteresting(blob);
 208                         return NULL;
 209                 }
 210                 add_pending_object(revs, object, "");
 211                 return NULL;
 212         }
 213         die("%s is unknown object", name);
 214 }
 215
 216 static int everybody_uninteresting(struct commit_list *orig)
 217 {
 218         struct commit_list *list = orig;
 219         while (list) {
 220                 struct commit *commit = list->item;
 221                 list = list->next;
 222                 if (commit->object.flags & UNINTERESTING)
 223                         continue;
 224                 return 0;
 225         }
 226         return 1;
 227 }
 228
 229 /*
 230  * The goal is to get REV_TREE_NEW as the result only if the
 231  * diff consists of all '+' (and no other changes), and
 232  * REV_TREE_DIFFERENT otherwise (of course if the trees are
 233  * the same we want REV_TREE_SAME).  That means that once we
 234  * get to REV_TREE_DIFFERENT, we do not have to look any further.
 235  */
 236 static int tree_difference = REV_TREE_SAME;
 237
 238 static void file_add_remove(struct diff_options *options,
 239                     int addremove, unsigned mode,
 240                     const unsigned char *sha1,
 241                     const char *base, const char *path)
 242 {
 243         int diff = REV_TREE_DIFFERENT;
 244
 245         /*
 246          * Is it an add of a new file? It means that the old tree
 247          * didn't have it at all, so we will turn "REV_TREE_SAME" ->
 248          * "REV_TREE_NEW", but leave any "REV_TREE_DIFFERENT" alone
 249          * (and if it already was "REV_TREE_NEW", we'll keep it
 250          * "REV_TREE_NEW" of course).
 251          */
 252         if (addremove == '+') {
 253                 diff = tree_difference;
 254                 if (diff != REV_TREE_SAME)
 255                         return;
 256                 diff = REV_TREE_NEW;
 257         }
 258         tree_difference = diff;
 259         if (tree_difference == REV_TREE_DIFFERENT)
 260                 options->has_changes = 1;
 261 }
 262
 263 static void file_change(struct diff_options *options,
 264                  unsigned old_mode, unsigned new_mode,
 265                  const unsigned char *old_sha1,
 266                  const unsigned char *new_sha1,
 267                  const char *base, const char *path)
 268 {
 269         tree_difference = REV_TREE_DIFFERENT;
 270         options->has_changes = 1;
 271 }
 272
 273 static int rev_compare_tree(struct rev_info *revs, struct tree *t1, struct tree *t2)
 274 {
 275         if (!t1)
 276                 return REV_TREE_NEW;
 277         if (!t2)
 278                 return REV_TREE_DIFFERENT;
 279         tree_difference = REV_TREE_SAME;
 280         revs->pruning.has_changes = 0;
 281         if (diff_tree_sha1(t1->object.sha1, t2->object.sha1, "",
 282                            &revs->pruning) < 0)
 283                 return REV_TREE_DIFFERENT;
 284         return tree_difference;
 285 }
 286
 287 static int rev_same_tree_as_empty(struct rev_info *revs, struct tree *t1)
 288 {
 289         int retval;
 290         void *tree;
 291         unsigned long size;
 292         struct tree_desc empty, real;
 293
 294         if (!t1)
 295                 return 0;
 296
 297         tree = read_object_with_reference(t1->object.sha1, tree_type, &size, NULL);
 298         if (!tree)
 299                 return 0;
 300         init_tree_desc(&real, tree, size);
 301         init_tree_desc(&empty, "", 0);
 302
 303         tree_difference = REV_TREE_SAME;
 304         revs->pruning.has_changes = 0;
 305         retval = diff_tree(&empty, &real, "", &revs->pruning);
 306         free(tree);
 307
 308         return retval >= 0 && (tree_difference == REV_TREE_SAME);
 309 }
 310
 311 static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
 312 {
 313         struct commit_list **pp, *parent;
 314         int tree_changed = 0, tree_same = 0;
 315
 316         if (!commit->tree)
 317                 return;
 318
 319         if (!commit->parents) {
 320                 if (!rev_same_tree_as_empty(revs, commit->tree))
 321                         commit->object.flags |= TREECHANGE;
 322                 return;
 323         }
 324
 325         pp = &commit->parents;
 326         while ((parent = *pp) != NULL) {
 327                 struct commit *p = parent->item;
 328
 329                 if (parse_commit(p) < 0)
 330                         die("cannot simplify commit %s (because of %s)",
 331                             sha1_to_hex(commit->object.sha1),
 332                             sha1_to_hex(p->object.sha1));
 333                 switch (rev_compare_tree(revs, p->tree, commit->tree)) {
 334                 case REV_TREE_SAME:
 335                         tree_same = 1;
 336                         if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
 337                                 /* Even if a merge with an uninteresting
 338                                  * side branch brought the entire change
 339                                  * we are interested in, we do not want
 340                                  * to lose the other branches of this
 341                                  * merge, so we just keep going.
 342                                  */
 343                                 pp = &parent->next;
 344                                 continue;
 345                         }
 346                         parent->next = NULL;
 347                         commit->parents = parent;
 348                         return;
 349
 350                 case REV_TREE_NEW:
 351                         if (revs->remove_empty_trees &&
 352                             rev_same_tree_as_empty(revs, p->tree)) {
 353                                 /* We are adding all the specified
 354                                  * paths from this parent, so the
 355                                  * history beyond this parent is not
 356                                  * interesting.  Remove its parents
 357                                  * (they are grandparents for us).
 358                                  * IOW, we pretend this parent is a
 359                                  * "root" commit.
 360                                  */
 361                                 if (parse_commit(p) < 0)
 362                                         die("cannot simplify commit %s (invalid %s)",
 363                                             sha1_to_hex(commit->object.sha1),
 364                                             sha1_to_hex(p->object.sha1));
 365                                 p->parents = NULL;
 366                         }
 367                 /* fallthrough */
 368                 case REV_TREE_DIFFERENT:
 369                         tree_changed = 1;
 370                         pp = &parent->next;
 371                         continue;
 372                 }
 373                 die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
 374         }
 375         if (tree_changed && !tree_same)
 376                 commit->object.flags |= TREECHANGE;
 377 }
 378
 379 static int add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 380 {
 381         struct commit_list *parent = commit->parents;
 382         unsigned left_flag;
 383         int add, rest;
 384
 385         if (commit->object.flags & ADDED)
 386                 return 0;
 387         commit->object.flags |= ADDED;
 388
 389         /*
 390          * If the commit is uninteresting, don't try to
 391          * prune parents - we want the maximal uninteresting
 392          * set.
 393          *
 394          * Normally we haven't parsed the parent
 395          * yet, so we won't have a parent of a parent
 396          * here. However, it may turn out that we've
 397          * reached this commit some other way (where it
 398          * wasn't uninteresting), in which case we need
 399          * to mark its parents recursively too..
 400          */
 401         if (commit->object.flags & UNINTERESTING) {
 402                 while (parent) {
 403                         struct commit *p = parent->item;
 404                         parent = parent->next;
 405                         if (parse_commit(p) < 0)
 406                                 return -1;
 407                         p->object.flags |= UNINTERESTING;
 408                         if (p->parents)
 409                                 mark_parents_uninteresting(p);
 410                         if (p->object.flags & SEEN)
 411                                 continue;
 412                         p->object.flags |= SEEN;
 413                         insert_by_date(p, list);
 414                 }
 415                 return 0;
 416         }
 417
 418         /*
 419          * Ok, the commit wasn't uninteresting. Try to
 420          * simplify the commit history and find the parent
 421          * that has no differences in the path set if one exists.
 422          */
 423         if (revs->prune_fn)
 424                 revs->prune_fn(revs, commit);
 425
 426         if (revs->no_walk)
 427                 return 0;
 428
 429         left_flag = (commit->object.flags & SYMMETRIC_LEFT);
 430
 431         rest = !revs->first_parent_only;
 432         for (parent = commit->parents, add = 1; parent; add = rest) {
 433                 struct commit *p = parent->item;
 434
 435                 parent = parent->next;
 436                 if (parse_commit(p) < 0)
 437                         return -1;
 438                 p->object.flags |= left_flag;
 439                 if (p->object.flags & SEEN)
 440                         continue;
 441                 p->object.flags |= SEEN;
 442                 if (add)
 443                         insert_by_date(p, list);
 444         }
 445         return 0;
 446 }
 447
 448 static void cherry_pick_list(struct commit_list *list, struct rev_info *revs)
 449 {
 450         struct commit_list *p;
 451         int left_count = 0, right_count = 0;
 452         int left_first;
 453         struct patch_ids ids;
 454
 455         /* First count the commits on the left and on the right */
 456         for (p = list; p; p = p->next) {
 457                 struct commit *commit = p->item;
 458                 unsigned flags = commit->object.flags;
 459                 if (flags & BOUNDARY)
 460                         ;
 461                 else if (flags & SYMMETRIC_LEFT)
 462                         left_count++;
 463                 else
 464                         right_count++;
 465         }
 466
 467         left_first = left_count < right_count;
 468         init_patch_ids(&ids);
 469         if (revs->diffopt.nr_paths) {
 470                 ids.diffopts.nr_paths = revs->diffopt.nr_paths;
 471                 ids.diffopts.paths = revs->diffopt.paths;
 472                 ids.diffopts.pathlens = revs->diffopt.pathlens;
 473         }
 474
 475         /* Compute patch-ids for one side */
 476         for (p = list; p; p = p->next) {
 477                 struct commit *commit = p->item;
 478                 unsigned flags = commit->object.flags;
 479
 480                 if (flags & BOUNDARY)
 481                         continue;
 482                 /*
 483                  * If we have fewer left, left_first is set and we omit
 484                  * commits on the right branch in this loop.  If we have
 485                  * fewer right, we skip the left ones.
 486                  */
 487                 if (left_first != !!(flags & SYMMETRIC_LEFT))
 488                         continue;
 489                 commit->util = add_commit_patch_id(commit, &ids);
 490         }
 491
 492         /* Check the other side */
 493         for (p = list; p; p = p->next) {
 494                 struct commit *commit = p->item;
 495                 struct patch_id *id;
 496                 unsigned flags = commit->object.flags;
 497
 498                 if (flags & BOUNDARY)
 499                         continue;
 500                 /*
 501                  * If we have fewer left, left_first is set and we omit
 502                  * commits on the left branch in this loop.
 503                  */
 504                 if (left_first == !!(flags & SYMMETRIC_LEFT))
 505                         continue;
 506
 507                 /*
 508                  * Have we seen the same patch id?
 509                  */
 510                 id = has_commit_patch_id(commit, &ids);
 511                 if (!id)
 512                         continue;
 513                 id->seen = 1;
 514                 commit->object.flags |= SHOWN;
 515         }
 516
 517         /* Now check the original side for seen ones */
 518         for (p = list; p; p = p->next) {
 519                 struct commit *commit = p->item;
 520                 struct patch_id *ent;
 521
 522                 ent = commit->util;
 523                 if (!ent)
 524                         continue;
 525                 if (ent->seen)
 526                         commit->object.flags |= SHOWN;
 527                 commit->util = NULL;
 528         }
 529
 530         free_patch_ids(&ids);
 531 }
 532
 533 static int limit_list(struct rev_info *revs)
 534 {
 535         struct commit_list *list = revs->commits;
 536         struct commit_list *newlist = NULL;
 537         struct commit_list **p = &newlist;
 538
 539         while (list) {
 540                 struct commit_list *entry = list;
 541                 struct commit *commit = list->item;
 542                 struct object *obj = &commit->object;
 543
 544                 list = list->next;
 545                 free(entry);
 546
 547                 if (revs->max_age != -1 && (commit->date < revs->max_age))
 548                         obj->flags |= UNINTERESTING;
 549                 if (add_parents_to_list(revs, commit, &list) < 0)
 550                         return -1;
 551                 if (obj->flags & UNINTERESTING) {
 552                         mark_parents_uninteresting(commit);
 553                         if (everybody_uninteresting(list))
 554                                 break;
 555                         continue;
 556                 }
 557                 if (revs->min_age != -1 && (commit->date > revs->min_age))
 558                         continue;
 559                 p = &commit_list_insert(commit, p)->next;
 560         }
 561         if (revs->cherry_pick)
 562                 cherry_pick_list(newlist, revs);
 563
 564         revs->commits = newlist;
 565         return 0;
 566 }
 567
 568 struct all_refs_cb {
 569         int all_flags;
 570         int warned_bad_reflog;
 571         struct rev_info *all_revs;
 572         const char *name_for_errormsg;
 573 };
 574
 575 static int handle_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 576 {
 577         struct all_refs_cb *cb = cb_data;
 578         struct object *object = get_reference(cb->all_revs, path, sha1,
 579                                               cb->all_flags);
 580         add_pending_object(cb->all_revs, object, path);
 581         return 0;
 582 }
 583
 584 static void handle_all(struct rev_info *revs, unsigned flags)
 585 {
 586         struct all_refs_cb cb;
 587         cb.all_revs = revs;
 588         cb.all_flags = flags;
 589         for_each_ref(handle_one_ref, &cb);
 590 }
 591
 592 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 593 {
 594         struct all_refs_cb *cb = cb_data;
 595         if (!is_null_sha1(sha1)) {
 596                 struct object *o = parse_object(sha1);
 597                 if (o) {
 598                         o->flags |= cb->all_flags;
 599                         add_pending_object(cb->all_revs, o, "");
 600                 }
 601                 else if (!cb->warned_bad_reflog) {
 602                         warning("reflog of '%s' references pruned commits",
 603                                 cb->name_for_errormsg);
 604                         cb->warned_bad_reflog = 1;
 605                 }
 606         }
 607 }
 608
 609 static int handle_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 610                 const char *email, unsigned long timestamp, int tz,
 611                 const char *message, void *cb_data)
 612 {
 613         handle_one_reflog_commit(osha1, cb_data);
 614         handle_one_reflog_commit(nsha1, cb_data);
 615         return 0;
 616 }
 617
 618 static int handle_one_reflog(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 619 {
 620         struct all_refs_cb *cb = cb_data;
 621         cb->warned_bad_reflog = 0;
 622         cb->name_for_errormsg = path;
 623         for_each_reflog_ent(path, handle_one_reflog_ent, cb_data);
 624         return 0;
 625 }
 626
 627 static void handle_reflog(struct rev_info *revs, unsigned flags)
 628 {
 629         struct all_refs_cb cb;
 630         cb.all_revs = revs;
 631         cb.all_flags = flags;
 632         for_each_reflog(handle_one_reflog, &cb);
 633 }
 634
 635 static int add_parents_only(struct rev_info *revs, const char *arg, int flags)
 636 {
 637         unsigned char sha1[20];
 638         struct object *it;
 639         struct commit *commit;
 640         struct commit_list *parents;
 641
 642         if (*arg == '^') {
 643                 flags ^= UNINTERESTING;
 644                 arg++;
 645         }
 646         if (get_sha1(arg, sha1))
 647                 return 0;
 648         while (1) {
 649                 it = get_reference(revs, arg, sha1, 0);
 650                 if (it->type != OBJ_TAG)
 651                         break;
 652                 hashcpy(sha1, ((struct tag*)it)->tagged->sha1);
 653         }
 654         if (it->type != OBJ_COMMIT)
 655                 return 0;
 656         commit = (struct commit *)it;
 657         for (parents = commit->parents; parents; parents = parents->next) {
 658                 it = &parents->item->object;
 659                 it->flags |= flags;
 660                 add_pending_object(revs, it, arg);
 661         }
 662         return 1;
 663 }
 664
 665 void init_revisions(struct rev_info *revs, const char *prefix)
 666 {
 667         memset(revs, 0, sizeof(*revs));
 668
 669         revs->abbrev = DEFAULT_ABBREV;
 670         revs->ignore_merges = 1;
 671         revs->simplify_history = 1;
 672         revs->pruning.recursive = 1;
 673         revs->pruning.quiet = 1;
 674         revs->pruning.add_remove = file_add_remove;
 675         revs->pruning.change = file_change;
 676         revs->lifo = 1;
 677         revs->dense = 1;
 678         revs->prefix = prefix;
 679         revs->max_age = -1;
 680         revs->min_age = -1;
 681         revs->skip_count = -1;
 682         revs->max_count = -1;
 683
 684         revs->prune_fn = NULL;
 685         revs->prune_data = NULL;
 686
 687         revs->topo_setter = topo_sort_default_setter;
 688         revs->topo_getter = topo_sort_default_getter;
 689
 690         revs->commit_format = CMIT_FMT_DEFAULT;
 691
 692         diff_setup(&revs->diffopt);
 693 }
 694
 695 static void add_pending_commit_list(struct rev_info *revs,
 696                                     struct commit_list *commit_list,
 697                                     unsigned int flags)
 698 {
 699         while (commit_list) {
 700                 struct object *object = &commit_list->item->object;
 701                 object->flags |= flags;
 702                 add_pending_object(revs, object, sha1_to_hex(object->sha1));
 703                 commit_list = commit_list->next;
 704         }
 705 }
 706
 707 static void prepare_show_merge(struct rev_info *revs)
 708 {
 709         struct commit_list *bases;
 710         struct commit *head, *other;
 711         unsigned char sha1[20];
 712         const char **prune = NULL;
 713         int i, prune_num = 1; /* counting terminating NULL */
 714
 715         if (get_sha1("HEAD", sha1) || !(head = lookup_commit(sha1)))
 716                 die("--merge without HEAD?");
 717         if (get_sha1("MERGE_HEAD", sha1) || !(other = lookup_commit(sha1)))
 718                 die("--merge without MERGE_HEAD?");
 719         add_pending_object(revs, &head->object, "HEAD");
 720         add_pending_object(revs, &other->object, "MERGE_HEAD");
 721         bases = get_merge_bases(head, other, 1);
 722         while (bases) {
 723                 struct commit *it = bases->item;
 724                 struct commit_list *n = bases->next;
 725                 free(bases);
 726                 bases = n;
 727                 it->object.flags |= UNINTERESTING;
 728                 add_pending_object(revs, &it->object, "(merge-base)");
 729         }
 730
 731         if (!active_nr)
 732                 read_cache();
 733         for (i = 0; i < active_nr; i++) {
 734                 struct cache_entry *ce = active_cache[i];
 735                 if (!ce_stage(ce))
 736                         continue;
 737                 if (ce_path_match(ce, revs->prune_data)) {
 738                         prune_num++;
 739                         prune = xrealloc(prune, sizeof(*prune) * prune_num);
 740                         prune[prune_num-2] = ce->name;
 741                         prune[prune_num-1] = NULL;
 742                 }
 743                 while ((i+1 < active_nr) &&
 744                        ce_same_name(ce, active_cache[i+1]))
 745                         i++;
 746         }
 747         revs->prune_data = prune;
 748 }
 749
 750 int handle_revision_arg(const char *arg, struct rev_info *revs,
 751                         int flags,
 752                         int cant_be_filename)
 753 {
 754         unsigned mode;
 755         char *dotdot;
 756         struct object *object;
 757         unsigned char sha1[20];
 758         int local_flags;
 759
 760         dotdot = strstr(arg, "..");
 761         if (dotdot) {
 762                 unsigned char from_sha1[20];
 763                 const char *next = dotdot + 2;
 764                 const char *this = arg;
 765                 int symmetric = *next == '.';
 766                 unsigned int flags_exclude = flags ^ UNINTERESTING;
 767
 768                 *dotdot = 0;
 769                 next += symmetric;
 770
 771                 if (!*next)
 772                         next = "HEAD";
 773                 if (dotdot == arg)
 774                         this = "HEAD";
 775                 if (!get_sha1(this, from_sha1) &&
 776                     !get_sha1(next, sha1)) {
 777                         struct commit *a, *b;
 778                         struct commit_list *exclude;
 779
 780                         a = lookup_commit_reference(from_sha1);
 781                         b = lookup_commit_reference(sha1);
 782                         if (!a || !b) {
 783                                 die(symmetric ?
 784                                     "Invalid symmetric difference expression %s...%s" :
 785                                     "Invalid revision range %s..%s",
 786                                     arg, next);
 787                         }
 788
 789                         if (!cant_be_filename) {
 790                                 *dotdot = '.';
 791                                 verify_non_filename(revs->prefix, arg);
 792                         }
 793
 794                         if (symmetric) {
 795                                 exclude = get_merge_bases(a, b, 1);
 796                                 add_pending_commit_list(revs, exclude,
 797                                                         flags_exclude);
 798                                 free_commit_list(exclude);
 799                                 a->object.flags |= flags | SYMMETRIC_LEFT;
 800                         } else
 801                                 a->object.flags |= flags_exclude;
 802                         b->object.flags |= flags;
 803                         add_pending_object(revs, &a->object, this);
 804                         add_pending_object(revs, &b->object, next);
 805                         return 0;
 806                 }
 807                 *dotdot = '.';
 808         }
 809         dotdot = strstr(arg, "^@");
 810         if (dotdot && !dotdot[2]) {
 811                 *dotdot = 0;
 812                 if (add_parents_only(revs, arg, flags))
 813                         return 0;
 814                 *dotdot = '^';
 815         }
 816         dotdot = strstr(arg, "^!");
 817         if (dotdot && !dotdot[2]) {
 818                 *dotdot = 0;
 819                 if (!add_parents_only(revs, arg, flags ^ UNINTERESTING))
 820                         *dotdot = '^';
 821         }
 822
 823         local_flags = 0;
 824         if (*arg == '^') {
 825                 local_flags = UNINTERESTING;
 826                 arg++;
 827         }
 828         if (get_sha1_with_mode(arg, sha1, &mode))
 829                 return -1;
 830         if (!cant_be_filename)
 831                 verify_non_filename(revs->prefix, arg);
 832         object = get_reference(revs, arg, sha1, flags ^ local_flags);
 833         add_pending_object_with_mode(revs, object, arg, mode);
 834         return 0;
 835 }
 836
 837 static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
 838 {
 839         if (!revs->grep_filter) {
 840                 struct grep_opt *opt = xcalloc(1, sizeof(*opt));
 841                 opt->status_only = 1;
 842                 opt->pattern_tail = &(opt->pattern_list);
 843                 opt->regflags = REG_NEWLINE;
 844                 revs->grep_filter = opt;
 845         }
 846         append_grep_pattern(revs->grep_filter, ptn,
 847                             "command line", 0, what);
 848 }
 849
 850 static void add_header_grep(struct rev_info *revs, const char *field, const char *pattern)
 851 {
 852         char *pat;
 853         const char *prefix;
 854         int patlen, fldlen;
 855
 856         fldlen = strlen(field);
 857         patlen = strlen(pattern);
 858         pat = xmalloc(patlen + fldlen + 10);
 859         prefix = ".*";
 860         if (*pattern == '^') {
 861                 prefix = "";
 862                 pattern++;
 863         }
 864         sprintf(pat, "^%s %s%s", field, prefix, pattern);
 865         add_grep(revs, pat, GREP_PATTERN_HEAD);
 866 }
 867
 868 static void add_message_grep(struct rev_info *revs, const char *pattern)
 869 {
 870         add_grep(revs, pattern, GREP_PATTERN_BODY);
 871 }
 872
 873 static void add_ignore_packed(struct rev_info *revs, const char *name)
 874 {
 875         int num = ++revs->num_ignore_packed;
 876
 877         revs->ignore_packed = xrealloc(revs->ignore_packed,
 878                                        sizeof(const char **) * (num + 1));
 879         revs->ignore_packed[num-1] = name;
 880         revs->ignore_packed[num] = NULL;
 881 }
 882
 883 /*
 884  * Parse revision information, filling in the "rev_info" structure,
 885  * and removing the used arguments from the argument list.
 886  *
 887  * Returns the number of arguments left that weren't recognized
 888  * (which are also moved to the head of the argument list)
 889  */
 890 int setup_revisions(int argc, const char **argv, struct rev_info *revs, const char *def)
 891 {
 892         int i, flags, seen_dashdash, show_merge;
 893         const char **unrecognized = argv + 1;
 894         int left = 1;
 895         int all_match = 0;
 896         int regflags = 0;
 897
 898         /* First, search for "--" */
 899         seen_dashdash = 0;
 900         for (i = 1; i < argc; i++) {
 901                 const char *arg = argv[i];
 902                 if (strcmp(arg, "--"))
 903                         continue;
 904                 argv[i] = NULL;
 905                 argc = i;
 906                 if (argv[i + 1])
 907                         revs->prune_data = get_pathspec(revs->prefix, argv + i + 1);
 908                 seen_dashdash = 1;
 909                 break;
 910         }
 911
 912         flags = show_merge = 0;
 913         for (i = 1; i < argc; i++) {
 914                 const char *arg = argv[i];
 915                 if (*arg == '-') {
 916                         int opts;
 917                         if (!prefixcmp(arg, "--max-count=")) {
 918                                 revs->max_count = atoi(arg + 12);
 919                                 continue;
 920                         }
 921                         if (!prefixcmp(arg, "--skip=")) {
 922                                 revs->skip_count = atoi(arg + 7);
 923                                 continue;
 924                         }
 925                         /* accept -<digit>, like traditional "head" */
 926                         if ((*arg == '-') && isdigit(arg[1])) {
 927                                 revs->max_count = atoi(arg + 1);
 928                                 continue;
 929                         }
 930                         if (!strcmp(arg, "-n")) {
 931                                 if (argc <= i + 1)
 932                                         die("-n requires an argument");
 933                                 revs->max_count = atoi(argv[++i]);
 934                                 continue;
 935                         }
 936                         if (!prefixcmp(arg, "-n")) {
 937                                 revs->max_count = atoi(arg + 2);
 938                                 continue;
 939                         }
 940                         if (!prefixcmp(arg, "--max-age=")) {
 941                                 revs->max_age = atoi(arg + 10);
 942                                 continue;
 943                         }
 944                         if (!prefixcmp(arg, "--since=")) {
 945                                 revs->max_age = approxidate(arg + 8);
 946                                 continue;
 947                         }
 948                         if (!prefixcmp(arg, "--after=")) {
 949                                 revs->max_age = approxidate(arg + 8);
 950                                 continue;
 951                         }
 952                         if (!prefixcmp(arg, "--min-age=")) {
 953                                 revs->min_age = atoi(arg + 10);
 954                                 continue;
 955                         }
 956                         if (!prefixcmp(arg, "--before=")) {
 957                                 revs->min_age = approxidate(arg + 9);
 958                                 continue;
 959                         }
 960                         if (!prefixcmp(arg, "--until=")) {
 961                                 revs->min_age = approxidate(arg + 8);
 962                                 continue;
 963                         }
 964                         if (!strcmp(arg, "--all")) {
 965                                 handle_all(revs, flags);
 966                                 continue;
 967                         }
 968                         if (!strcmp(arg, "--first-parent")) {
 969                                 revs->first_parent_only = 1;
 970                                 continue;
 971                         }
 972                         if (!strcmp(arg, "--reflog")) {
 973                                 handle_reflog(revs, flags);
 974                                 continue;
 975                         }
 976                         if (!strcmp(arg, "-g") ||
 977                                         !strcmp(arg, "--walk-reflogs")) {
 978                                 init_reflog_walk(&revs->reflog_info);
 979                                 continue;
 980                         }
 981                         if (!strcmp(arg, "--not")) {
 982                                 flags ^= UNINTERESTING;
 983                                 continue;
 984                         }
 985                         if (!strcmp(arg, "--default")) {
 986                                 if (++i >= argc)
 987                                         die("bad --default argument");
 988                                 def = argv[i];
 989                                 continue;
 990                         }
 991                         if (!strcmp(arg, "--merge")) {
 992                                 show_merge = 1;
 993                                 continue;
 994                         }
 995                         if (!strcmp(arg, "--topo-order")) {
 996                                 revs->topo_order = 1;
 997                                 continue;
 998                         }
 999                         if (!strcmp(arg, "--date-order")) {
1000                                 revs->lifo = 0;
1001                                 revs->topo_order = 1;
1002                                 continue;
1003                         }
1004                         if (!strcmp(arg, "--parents")) {
1005                                 revs->parents = 1;
1006                                 continue;
1007                         }
1008                         if (!strcmp(arg, "--dense")) {
1009                                 revs->dense = 1;
1010                                 continue;
1011                         }
1012                         if (!strcmp(arg, "--sparse")) {
1013                                 revs->dense = 0;
1014                                 continue;
1015                         }
1016                         if (!strcmp(arg, "--remove-empty")) {
1017                                 revs->remove_empty_trees = 1;
1018                                 continue;
1019                         }
1020                         if (!strcmp(arg, "--no-merges")) {
1021                                 revs->no_merges = 1;
1022                                 continue;
1023                         }
1024                         if (!strcmp(arg, "--boundary")) {
1025                                 revs->boundary = 1;
1026                                 continue;
1027                         }
1028                         if (!strcmp(arg, "--left-right")) {
1029                                 revs->left_right = 1;
1030                                 continue;
1031                         }
1032                         if (!strcmp(arg, "--cherry-pick")) {
1033                                 revs->cherry_pick = 1;
1034                                 revs->limited = 1;
1035                                 continue;
1036                         }
1037                         if (!strcmp(arg, "--objects")) {
1038                                 revs->tag_objects = 1;
1039                                 revs->tree_objects = 1;
1040                                 revs->blob_objects = 1;
1041                                 continue;
1042                         }
1043                         if (!strcmp(arg, "--objects-edge")) {
1044                                 revs->tag_objects = 1;
1045                                 revs->tree_objects = 1;
1046                                 revs->blob_objects = 1;
1047                                 revs->edge_hint = 1;
1048                                 continue;
1049                         }
1050                         if (!strcmp(arg, "--unpacked")) {
1051                                 revs->unpacked = 1;
1052                                 free(revs->ignore_packed);
1053                                 revs->ignore_packed = NULL;
1054                                 revs->num_ignore_packed = 0;
1055                                 continue;
1056                         }
1057                         if (!prefixcmp(arg, "--unpacked=")) {
1058                                 revs->unpacked = 1;
1059                                 add_ignore_packed(revs, arg+11);
1060                                 continue;
1061                         }
1062                         if (!strcmp(arg, "-r")) {
1063                                 revs->diff = 1;
1064                                 revs->diffopt.recursive = 1;
1065                                 continue;
1066                         }
1067                         if (!strcmp(arg, "-t")) {
1068                                 revs->diff = 1;
1069                                 revs->diffopt.recursive = 1;
1070                                 revs->diffopt.tree_in_recursive = 1;
1071                                 continue;
1072                         }
1073                         if (!strcmp(arg, "-m")) {
1074                                 revs->ignore_merges = 0;
1075                                 continue;
1076                         }
1077                         if (!strcmp(arg, "-c")) {
1078                                 revs->diff = 1;
1079                                 revs->dense_combined_merges = 0;
1080                                 revs->combine_merges = 1;
1081                                 continue;
1082                         }
1083                         if (!strcmp(arg, "--cc")) {
1084                                 revs->diff = 1;
1085                                 revs->dense_combined_merges = 1;
1086                                 revs->combine_merges = 1;
1087                                 continue;
1088                         }
1089                         if (!strcmp(arg, "-v")) {
1090                                 revs->verbose_header = 1;
1091                                 continue;
1092                         }
1093                         if (!prefixcmp(arg, "--pretty")) {
1094                                 revs->verbose_header = 1;
1095                                 revs->commit_format = get_commit_format(arg+8);
1096                                 continue;
1097                         }
1098                         if (!strcmp(arg, "--root")) {
1099                                 revs->show_root_diff = 1;
1100                                 continue;
1101                         }
1102                         if (!strcmp(arg, "--no-commit-id")) {
1103                                 revs->no_commit_id = 1;
1104                                 continue;
1105                         }
1106                         if (!strcmp(arg, "--always")) {
1107                                 revs->always_show_header = 1;
1108                                 continue;
1109                         }
1110                         if (!strcmp(arg, "--no-abbrev")) {
1111                                 revs->abbrev = 0;
1112                                 continue;
1113                         }
1114                         if (!strcmp(arg, "--abbrev")) {
1115                                 revs->abbrev = DEFAULT_ABBREV;
1116                                 continue;
1117                         }
1118                         if (!prefixcmp(arg, "--abbrev=")) {
1119                                 revs->abbrev = strtoul(arg + 9, NULL, 10);
1120                                 if (revs->abbrev < MINIMUM_ABBREV)
1121                                         revs->abbrev = MINIMUM_ABBREV;
1122                                 else if (revs->abbrev > 40)
1123                                         revs->abbrev = 40;
1124                                 continue;
1125                         }
1126                         if (!strcmp(arg, "--abbrev-commit")) {
1127                                 revs->abbrev_commit = 1;
1128                                 continue;
1129                         }
1130                         if (!strcmp(arg, "--full-diff")) {
1131                                 revs->diff = 1;
1132                                 revs->full_diff = 1;
1133                                 continue;
1134                         }
1135                         if (!strcmp(arg, "--full-history")) {
1136                                 revs->simplify_history = 0;
1137                                 continue;
1138                         }
1139                         if (!strcmp(arg, "--relative-date")) {
1140                                 revs->date_mode = DATE_RELATIVE;
1141                                 continue;
1142                         }
1143                         if (!strncmp(arg, "--date=", 7)) {
1144                                 if (!strcmp(arg + 7, "relative"))
1145                                         revs->date_mode = DATE_RELATIVE;
1146                                 else if (!strcmp(arg + 7, "iso8601") ||
1147                                          !strcmp(arg + 7, "iso"))
1148                                         revs->date_mode = DATE_ISO8601;
1149                                 else if (!strcmp(arg + 7, "rfc2822") ||
1150                                          !strcmp(arg + 7, "rfc"))
1151                                         revs->date_mode = DATE_RFC2822;
1152                                 else if (!strcmp(arg + 7, "short"))
1153                                         revs->date_mode = DATE_SHORT;
1154                                 else if (!strcmp(arg + 7, "local"))
1155                                         revs->date_mode = DATE_LOCAL;
1156                                 else if (!strcmp(arg + 7, "default"))
1157                                         revs->date_mode = DATE_NORMAL;
1158                                 else
1159                                         die("unknown date format %s", arg);
1160                                 continue;
1161                         }
1162                         if (!strcmp(arg, "--log-size")) {
1163                                 revs->show_log_size = 1;
1164                                 continue;
1165                         }
1166
1167                         /*
1168                          * Grepping the commit log
1169                          */
1170                         if (!prefixcmp(arg, "--author=")) {
1171                                 add_header_grep(revs, "author", arg+9);
1172                                 continue;
1173                         }
1174                         if (!prefixcmp(arg, "--committer=")) {
1175                                 add_header_grep(revs, "committer", arg+12);
1176                                 continue;
1177                         }
1178                         if (!prefixcmp(arg, "--grep=")) {
1179                                 add_message_grep(revs, arg+7);
1180                                 continue;
1181                         }
1182                         if (!strcmp(arg, "--extended-regexp") ||
1183                             !strcmp(arg, "-E")) {
1184                                 regflags |= REG_EXTENDED;
1185                                 continue;
1186                         }
1187                         if (!strcmp(arg, "--regexp-ignore-case") ||
1188                             !strcmp(arg, "-i")) {
1189                                 regflags |= REG_ICASE;
1190                                 continue;
1191                         }
1192                         if (!strcmp(arg, "--all-match")) {
1193                                 all_match = 1;
1194                                 continue;
1195                         }
1196                         if (!prefixcmp(arg, "--encoding=")) {
1197                                 arg += 11;
1198                                 if (strcmp(arg, "none"))
1199                                         git_log_output_encoding = xstrdup(arg);
1200                                 else
1201                                         git_log_output_encoding = "";
1202                                 continue;
1203                         }
1204                         if (!strcmp(arg, "--reverse")) {
1205                                 revs->reverse ^= 1;
1206                                 continue;
1207                         }
1208                         if (!strcmp(arg, "--no-walk")) {
1209                                 revs->no_walk = 1;
1210                                 continue;
1211                         }
1212                         if (!strcmp(arg, "--do-walk")) {
1213                                 revs->no_walk = 0;
1214                                 continue;
1215                         }
1216
1217                         opts = diff_opt_parse(&revs->diffopt, argv+i, argc-i);
1218                         if (opts > 0) {
1219                                 i += opts - 1;
1220                                 continue;
1221                         }
1222                         *unrecognized++ = arg;
1223                         left++;
1224                         continue;
1225                 }
1226
1227                 if (handle_revision_arg(arg, revs, flags, seen_dashdash)) {
1228                         int j;
1229                         if (seen_dashdash || *arg == '^')
1230                                 die("bad revision '%s'", arg);
1231
1232                         /* If we didn't have a "--":
1233                          * (1) all filenames must exist;
1234                          * (2) all rev-args must not be interpretable
1235                          *     as a valid filename.
1236                          * but the latter we have checked in the main loop.
1237                          */
1238                         for (j = i; j < argc; j++)
1239                                 verify_filename(revs->prefix, argv[j]);
1240
1241                         revs->prune_data = get_pathspec(revs->prefix,
1242                                                         argv + i);
1243                         break;
1244                 }
1245         }
1246
1247         if (revs->grep_filter)
1248                 revs->grep_filter->regflags |= regflags;
1249
1250         if (show_merge)
1251                 prepare_show_merge(revs);
1252         if (def && !revs->pending.nr) {
1253                 unsigned char sha1[20];
1254                 struct object *object;
1255                 unsigned mode;
1256                 if (get_sha1_with_mode(def, sha1, &mode))
1257                         die("bad default revision '%s'", def);
1258                 object = get_reference(revs, def, sha1, 0);
1259                 add_pending_object_with_mode(revs, object, def, mode);
1260         }
1261
1262         /* Did the user ask for any diff output? Run the diff! */
1263         if (revs->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT)
1264                 revs->diff = 1;
1265
1266         /* Pickaxe and rename following needs diffs */
1267         if (revs->diffopt.pickaxe || revs->diffopt.follow_renames)
1268                 revs->diff = 1;
1269
1270         if (revs->topo_order)
1271                 revs->limited = 1;
1272
1273         if (revs->prune_data) {
1274                 diff_tree_setup_paths(revs->prune_data, &revs->pruning);
1275                 /* Can't prune commits with rename following: the paths change.. */
1276                 if (!revs->diffopt.follow_renames)
1277                         revs->prune_fn = try_to_simplify_commit;
1278                 if (!revs->full_diff)
1279                         diff_tree_setup_paths(revs->prune_data, &revs->diffopt);
1280         }
1281         if (revs->combine_merges) {
1282                 revs->ignore_merges = 0;
1283                 if (revs->dense_combined_merges && !revs->diffopt.output_format)
1284                         revs->diffopt.output_format = DIFF_FORMAT_PATCH;
1285         }
1286         revs->diffopt.abbrev = revs->abbrev;
1287         if (diff_setup_done(&revs->diffopt) < 0)
1288                 die("diff_setup_done failed");
1289
1290         if (revs->grep_filter) {
1291                 revs->grep_filter->all_match = all_match;
1292                 compile_grep_patterns(revs->grep_filter);
1293         }
1294
1295         if (revs->reverse && revs->reflog_info)
1296                 die("cannot combine --reverse with --walk-reflogs");
1297
1298         return left;
1299 }
1300
1301 int prepare_revision_walk(struct rev_info *revs)
1302 {
1303         int nr = revs->pending.nr;
1304         struct object_array_entry *e, *list;
1305
1306         e = list = revs->pending.objects;
1307         revs->pending.nr = 0;
1308         revs->pending.alloc = 0;
1309         revs->pending.objects = NULL;
1310         while (--nr >= 0) {
1311                 struct commit *commit = handle_commit(revs, e->item, e->name);
1312                 if (commit) {
1313                         if (!(commit->object.flags & SEEN)) {
1314                                 commit->object.flags |= SEEN;
1315                                 insert_by_date(commit, &revs->commits);
1316                         }
1317                 }
1318                 e++;
1319         }
1320         free(list);
1321
1322         if (revs->no_walk)
1323                 return 0;
1324         if (revs->limited)
1325                 if (limit_list(revs) < 0)
1326                         return -1;
1327         if (revs->topo_order)
1328                 sort_in_topological_order_fn(&revs->commits, revs->lifo,
1329                                              revs->topo_setter,
1330                                              revs->topo_getter);
1331         return 0;
1332 }
1333
1334 enum rewrite_result {
1335         rewrite_one_ok,
1336         rewrite_one_noparents,
1337         rewrite_one_error,
1338 };
1339
1340 static enum rewrite_result rewrite_one(struct rev_info *revs, struct commit **pp)
1341 {
1342         for (;;) {
1343                 struct commit *p = *pp;
1344                 if (!revs->limited)
1345                         if (add_parents_to_list(revs, p, &revs->commits) < 0)
1346                                 return rewrite_one_error;
1347                 if (p->parents && p->parents->next)
1348                         return rewrite_one_ok;
1349                 if (p->object.flags & (TREECHANGE | UNINTERESTING))
1350                         return rewrite_one_ok;
1351                 if (!p->parents)
1352                         return rewrite_one_noparents;
1353                 *pp = p->parents->item;
1354         }
1355 }
1356
1357 static void remove_duplicate_parents(struct commit *commit)
1358 {
1359         struct commit_list **pp, *p;
1360
1361         /* Examine existing parents while marking ones we have seen... */
1362         pp = &commit->parents;
1363         while ((p = *pp) != NULL) {
1364                 struct commit *parent = p->item;
1365                 if (parent->object.flags & TMP_MARK) {
1366                         *pp = p->next;
1367                         continue;
1368                 }
1369                 parent->object.flags |= TMP_MARK;
1370                 pp = &p->next;
1371         }
1372         /* ... and clear the temporary mark */
1373         for (p = commit->parents; p; p = p->next)
1374                 p->item->object.flags &= ~TMP_MARK;
1375 }
1376
1377 static int rewrite_parents(struct rev_info *revs, struct commit *commit)
1378 {
1379         struct commit_list **pp = &commit->parents;
1380         while (*pp) {
1381                 struct commit_list *parent = *pp;
1382                 switch (rewrite_one(revs, &parent->item)) {
1383                 case rewrite_one_ok:
1384                         break;
1385                 case rewrite_one_noparents:
1386                         *pp = parent->next;
1387                         continue;
1388                 case rewrite_one_error:
1389                         return -1;
1390                 }
1391                 pp = &parent->next;
1392         }
1393         remove_duplicate_parents(commit);
1394         return 0;
1395 }
1396
1397 static int commit_match(struct commit *commit, struct rev_info *opt)
1398 {
1399         if (!opt->grep_filter)
1400                 return 1;
1401         return grep_buffer(opt->grep_filter,
1402                            NULL, /* we say nothing, not even filename */
1403                            commit->buffer, strlen(commit->buffer));
1404 }
1405
1406 static struct commit *get_revision_1(struct rev_info *revs)
1407 {
1408         if (!revs->commits)
1409                 return NULL;
1410
1411         do {
1412                 struct commit_list *entry = revs->commits;
1413                 struct commit *commit = entry->item;
1414
1415                 revs->commits = entry->next;
1416                 free(entry);
1417
1418                 if (revs->reflog_info)
1419                         fake_reflog_parent(revs->reflog_info, commit);
1420
1421                 /*
1422                  * If we haven't done the list limiting, we need to look at
1423                  * the parents here. We also need to do the date-based limiting
1424                  * that we'd otherwise have done in limit_list().
1425                  */
1426                 if (!revs->limited) {
1427                         if (revs->max_age != -1 &&
1428                             (commit->date < revs->max_age))
1429                                 continue;
1430                         if (add_parents_to_list(revs, commit, &revs->commits) < 0)
1431                                 return NULL;
1432                 }
1433                 if (commit->object.flags & SHOWN)
1434                         continue;
1435
1436                 if (revs->unpacked && has_sha1_pack(commit->object.sha1,
1437                                                     revs->ignore_packed))
1438                     continue;
1439
1440                 if (commit->object.flags & UNINTERESTING)
1441                         continue;
1442                 if (revs->min_age != -1 && (commit->date > revs->min_age))
1443                         continue;
1444                 if (revs->no_merges &&
1445                     commit->parents && commit->parents->next)
1446                         continue;
1447                 if (!commit_match(commit, revs))
1448                         continue;
1449                 if (revs->prune_fn && revs->dense) {
1450                         /* Commit without changes? */
1451                         if (!(commit->object.flags & TREECHANGE)) {
1452                                 /* drop merges unless we want parenthood */
1453                                 if (!revs->parents)
1454                                         continue;
1455                                 /* non-merge - always ignore it */
1456                                 if (!commit->parents || !commit->parents->next)
1457                                         continue;
1458                         }
1459                         if (revs->parents && rewrite_parents(revs, commit) < 0)
1460                                 return NULL;
1461                 }
1462                 return commit;
1463         } while (revs->commits);
1464         return NULL;
1465 }
1466
1467 static void gc_boundary(struct object_array *array)
1468 {
1469         unsigned nr = array->nr;
1470         unsigned alloc = array->alloc;
1471         struct object_array_entry *objects = array->objects;
1472
1473         if (alloc <= nr) {
1474                 unsigned i, j;
1475                 for (i = j = 0; i < nr; i++) {
1476                         if (objects[i].item->flags & SHOWN)
1477                                 continue;
1478                         if (i != j)
1479                                 objects[j] = objects[i];
1480                         j++;
1481                 }
1482                 for (i = j; i < nr; i++)
1483                         objects[i].item = NULL;
1484                 array->nr = j;
1485         }
1486 }
1487
1488 struct commit *get_revision(struct rev_info *revs)
1489 {
1490         struct commit *c = NULL;
1491         struct commit_list *l;
1492
1493         if (revs->boundary == 2) {
1494                 unsigned i;
1495                 struct object_array *array = &revs->boundary_commits;
1496                 struct object_array_entry *objects = array->objects;
1497                 for (i = 0; i < array->nr; i++) {
1498                         c = (struct commit *)(objects[i].item);
1499                         if (!c)
1500                                 continue;
1501                         if (!(c->object.flags & CHILD_SHOWN))
1502                                 continue;
1503                         if (!(c->object.flags & SHOWN))
1504                                 break;
1505                 }
1506                 if (array->nr <= i)
1507                         return NULL;
1508
1509                 c->object.flags |= SHOWN | BOUNDARY;
1510                 return c;
1511         }
1512
1513         if (revs->reverse) {
1514                 int limit = -1;
1515
1516                 if (0 <= revs->max_count) {
1517                         limit = revs->max_count;
1518                         if (0 < revs->skip_count)
1519                                 limit += revs->skip_count;
1520                 }
1521                 l = NULL;
1522                 while ((c = get_revision_1(revs))) {
1523                         commit_list_insert(c, &l);
1524                         if ((0 < limit) && !--limit)
1525                                 break;
1526                 }
1527                 revs->commits = l;
1528                 revs->reverse = 0;
1529                 revs->max_count = -1;
1530                 c = NULL;
1531         }
1532
1533         /*
1534          * Now pick up what they want to give us
1535          */
1536         c = get_revision_1(revs);
1537         if (c) {
1538                 while (0 < revs->skip_count) {
1539                         revs->skip_count--;
1540                         c = get_revision_1(revs);
1541                         if (!c)
1542                                 break;
1543                 }
1544         }
1545
1546         /*
1547          * Check the max_count.
1548          */
1549         switch (revs->max_count) {
1550         case -1:
1551                 break;
1552         case 0:
1553                 c = NULL;
1554                 break;
1555         default:
1556                 revs->max_count--;
1557         }
1558
1559         if (c)
1560                 c->object.flags |= SHOWN;
1561
1562         if (!revs->boundary) {
1563                 return c;
1564         }
1565
1566         if (!c) {
1567                 /*
1568                  * get_revision_1() runs out the commits, and
1569                  * we are done computing the boundaries.
1570                  * switch to boundary commits output mode.
1571                  */
1572                 revs->boundary = 2;
1573                 return get_revision(revs);
1574         }
1575
1576         /*
1577          * boundary commits are the commits that are parents of the
1578          * ones we got from get_revision_1() but they themselves are
1579          * not returned from get_revision_1().  Before returning
1580          * 'c', we need to mark its parents that they could be boundaries.
1581          */
1582
1583         for (l = c->parents; l; l = l->next) {
1584                 struct object *p;
1585                 p = &(l->item->object);
1586                 if (p->flags & (CHILD_SHOWN | SHOWN))
1587                         continue;
1588                 p->flags |= CHILD_SHOWN;
1589                 gc_boundary(&revs->boundary_commits);
1590                 add_object_array(p, NULL, &revs->boundary_commits);
1591         }
1592
1593         return c;
1594 }