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