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