summaryrefslogtreecommitdiff
path: root/sequencer.c
blob: c6362d63f35fe37d67fa235784ab8ce75a60db44 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
#include "cache.h"
#include "lockfile.h"
#include "sequencer.h"
#include "dir.h"
#include "object.h"
#include "commit.h"
#include "tag.h"
#include "run-command.h"
#include "exec_cmd.h"
#include "utf8.h"
#include "cache-tree.h"
#include "diff.h"
#include "revision.h"
#include "rerere.h"
#include "merge-recursive.h"
#include "refs.h"
#include "argv-array.h"

#define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"

const char sign_off_header[] = "Signed-off-by: ";
static const char cherry_picked_prefix[] = "(cherry picked from commit ";

static GIT_PATH_FUNC(git_path_todo_file, SEQ_TODO_FILE)
static GIT_PATH_FUNC(git_path_opts_file, SEQ_OPTS_FILE)
static GIT_PATH_FUNC(git_path_seq_dir, SEQ_DIR)
static GIT_PATH_FUNC(git_path_head_file, SEQ_HEAD_FILE)

static int is_rfc2822_line(const char *buf, int len)
{
	int i;

	for (i = 0; i < len; i++) {
		int ch = buf[i];
		if (ch == ':')
			return 1;
		if (!isalnum(ch) && ch != '-')
			break;
	}

	return 0;
}

static int is_cherry_picked_from_line(const char *buf, int len)
{
	/*
	 * We only care that it looks roughly like (cherry picked from ...)
	 */
	return len > strlen(cherry_picked_prefix) + 1 &&
		starts_with(buf, cherry_picked_prefix) && buf[len - 1] == ')';
}

/*
 * Returns 0 for non-conforming footer
 * Returns 1 for conforming footer
 * Returns 2 when sob exists within conforming footer
 * Returns 3 when sob exists within conforming footer as last entry
 */
static int has_conforming_footer(struct strbuf *sb, struct strbuf *sob,
	int ignore_footer)
{
	char prev;
	int i, k;
	int len = sb->len - ignore_footer;
	const char *buf = sb->buf;
	int found_sob = 0;

	/* footer must end with newline */
	if (!len || buf[len - 1] != '\n')
		return 0;

	prev = '\0';
	for (i = len - 1; i > 0; i--) {
		char ch = buf[i];
		if (prev == '\n' && ch == '\n') /* paragraph break */
			break;
		prev = ch;
	}

	/* require at least one blank line */
	if (prev != '\n' || buf[i] != '\n')
		return 0;

	/* advance to start of last paragraph */
	while (i < len - 1 && buf[i] == '\n')
		i++;

	for (; i < len; i = k) {
		int found_rfc2822;

		for (k = i; k < len && buf[k] != '\n'; k++)
			; /* do nothing */
		k++;

		found_rfc2822 = is_rfc2822_line(buf + i, k - i - 1);
		if (found_rfc2822 && sob &&
		    !strncmp(buf + i, sob->buf, sob->len))
			found_sob = k;

		if (!(found_rfc2822 ||
		      is_cherry_picked_from_line(buf + i, k - i - 1)))
			return 0;
	}
	if (found_sob == i)
		return 3;
	if (found_sob)
		return 2;
	return 1;
}

static void remove_sequencer_state(void)
{
	struct strbuf seq_dir = STRBUF_INIT;

	strbuf_addf(&seq_dir, "%s", git_path(SEQ_DIR));
	remove_dir_recursively(&seq_dir, 0);
	strbuf_release(&seq_dir);
}

static const char *action_name(const struct replay_opts *opts)
{
	return opts->action == REPLAY_REVERT ? "revert" : "cherry-pick";
}

struct commit_message {
	char *parent_label;
	char *label;
	char *subject;
	const char *message;
};

static int get_message(struct commit *commit, struct commit_message *out)
{
	const char *abbrev, *subject;
	int subject_len;

	out->message = logmsg_reencode(commit, NULL, get_commit_output_encoding());
	abbrev = find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV);

	subject_len = find_commit_subject(out->message, &subject);

	out->subject = xmemdupz(subject, subject_len);
	out->label = xstrfmt("%s... %s", abbrev, out->subject);
	out->parent_label = xstrfmt("parent of %s", out->label);

	return 0;
}

static void free_message(struct commit *commit, struct commit_message *msg)
{
	free(msg->parent_label);
	free(msg->label);
	free(msg->subject);
	unuse_commit_buffer(commit, msg->message);
}

static void print_advice(int show_hint, struct replay_opts *opts)
{
	char *msg = getenv("GIT_CHERRY_PICK_HELP");

	if (msg) {
		fprintf(stderr, "%s\n", msg);
		/*
		 * A conflict has occurred but the porcelain
		 * (typically rebase --interactive) wants to take care
		 * of the commit itself so remove CHERRY_PICK_HEAD
		 */
		unlink(git_path_cherry_pick_head());
		return;
	}

	if (show_hint) {
		if (opts->no_commit)
			advise(_("after resolving the conflicts, mark the corrected paths\n"
				 "with 'git add <paths>' or 'git rm <paths>'"));
		else
			advise(_("after resolving the conflicts, mark the corrected paths\n"
				 "with 'git add <paths>' or 'git rm <paths>'\n"
				 "and commit the result with 'git commit'"));
	}
}

static void write_message(struct strbuf *msgbuf, const char *filename)
{
	static struct lock_file msg_file;

	int msg_fd = hold_lock_file_for_update(&msg_file, filename,
					       LOCK_DIE_ON_ERROR);
	if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
		die_errno(_("Could not write to %s"), filename);
	strbuf_release(msgbuf);
	if (commit_lock_file(&msg_file) < 0)
		die(_("Error wrapping up %s"), filename);
}

static struct tree *empty_tree(void)
{
	return lookup_tree(EMPTY_TREE_SHA1_BIN);
}

static int error_dirty_index(struct replay_opts *opts)
{
	if (read_cache_unmerged())
		return error_resolve_conflict(action_name(opts));

	/* Different translation strings for cherry-pick and revert */
	if (opts->action == REPLAY_PICK)
		error(_("Your local changes would be overwritten by cherry-pick."));
	else
		error(_("Your local changes would be overwritten by revert."));

	if (advice_commit_before_merge)
		advise(_("Commit your changes or stash them to proceed."));
	return -1;
}

static int fast_forward_to(const unsigned char *to, const unsigned char *from,
			int unborn, struct replay_opts *opts)
{
	struct ref_transaction *transaction;
	struct strbuf sb = STRBUF_INIT;
	struct strbuf err = STRBUF_INIT;

	read_cache();
	if (checkout_fast_forward(from, to, 1))
		exit(128); /* the callee should have complained already */

	strbuf_addf(&sb, "%s: fast-forward", action_name(opts));

	transaction = ref_transaction_begin(&err);
	if (!transaction ||
	    ref_transaction_update(transaction, "HEAD",
				   to, unborn ? null_sha1 : from,
				   0, sb.buf, &err) ||
	    ref_transaction_commit(transaction, &err)) {
		ref_transaction_free(transaction);
		error("%s", err.buf);
		strbuf_release(&sb);
		strbuf_release(&err);
		return -1;
	}

	strbuf_release(&sb);
	strbuf_release(&err);
	ref_transaction_free(transaction);
	return 0;
}

void append_conflicts_hint(struct strbuf *msgbuf)
{
	int i;

	strbuf_addch(msgbuf, '\n');
	strbuf_commented_addf(msgbuf, "Conflicts:\n");
	for (i = 0; i < active_nr;) {
		const struct cache_entry *ce = active_cache[i++];
		if (ce_stage(ce)) {
			strbuf_commented_addf(msgbuf, "\t%s\n", ce->name);
			while (i < active_nr && !strcmp(ce->name,
							active_cache[i]->name))
				i++;
		}
	}
}

static int do_recursive_merge(struct commit *base, struct commit *next,
			      const char *base_label, const char *next_label,
			      unsigned char *head, struct strbuf *msgbuf,
			      struct replay_opts *opts)
{
	struct merge_options o;
	struct tree *result, *next_tree, *base_tree, *head_tree;
	int clean;
	const char **xopt;
	static struct lock_file index_lock;

	hold_locked_index(&index_lock, 1);

	read_cache();

	init_merge_options(&o);
	o.ancestor = base ? base_label : "(empty tree)";
	o.branch1 = "HEAD";
	o.branch2 = next ? next_label : "(empty tree)";

	head_tree = parse_tree_indirect(head);
	next_tree = next ? next->tree : empty_tree();
	base_tree = base ? base->tree : empty_tree();

	for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
		parse_merge_opt(&o, *xopt);

	clean = merge_trees(&o,
			    head_tree,
			    next_tree, base_tree, &result);

	if (active_cache_changed &&
	    write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
		/* TRANSLATORS: %s will be "revert" or "cherry-pick" */
		die(_("%s: Unable to write new index file"), action_name(opts));
	rollback_lock_file(&index_lock);

	if (opts->signoff)
		append_signoff(msgbuf, 0, 0);

	if (!clean)
		append_conflicts_hint(msgbuf);

	return !clean;
}

static int is_index_unchanged(void)
{
	unsigned char head_sha1[20];
	struct commit *head_commit;

	if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, head_sha1, NULL))
		return error(_("Could not resolve HEAD commit\n"));

	head_commit = lookup_commit(head_sha1);

	/*
	 * If head_commit is NULL, check_commit, called from
	 * lookup_commit, would have indicated that head_commit is not
	 * a commit object already.  parse_commit() will return failure
	 * without further complaints in such a case.  Otherwise, if
	 * the commit is invalid, parse_commit() will complain.  So
	 * there is nothing for us to say here.  Just return failure.
	 */
	if (parse_commit(head_commit))
		return -1;

	if (!active_cache_tree)
		active_cache_tree = cache_tree();

	if (!cache_tree_fully_valid(active_cache_tree))
		if (cache_tree_update(&the_index, 0))
			return error(_("Unable to update cache tree\n"));

	return !hashcmp(active_cache_tree->sha1, head_commit->tree->object.oid.hash);
}

/*
 * If we are cherry-pick, and if the merge did not result in
 * hand-editing, we will hit this commit and inherit the original
 * author date and name.
 * If we are revert, or if our cherry-pick results in a hand merge,
 * we had better say that the current user is responsible for that.
 */
static int run_git_commit(const char *defmsg, struct replay_opts *opts,
			  int allow_empty)
{
	struct argv_array array;
	int rc;
	const char *value;

	argv_array_init(&array);
	argv_array_push(&array, "commit");
	argv_array_push(&array, "-n");

	if (opts->gpg_sign)
		argv_array_pushf(&array, "-S%s", opts->gpg_sign);
	if (opts->signoff)
		argv_array_push(&array, "-s");
	if (!opts->edit) {
		argv_array_push(&array, "-F");
		argv_array_push(&array, defmsg);
		if (!opts->signoff &&
		    !opts->record_origin &&
		    git_config_get_value("commit.cleanup", &value))
			argv_array_push(&array, "--cleanup=verbatim");
	}

	if (allow_empty)
		argv_array_push(&array, "--allow-empty");

	if (opts->allow_empty_message)
		argv_array_push(&array, "--allow-empty-message");

	rc = run_command_v_opt(array.argv, RUN_GIT_CMD);
	argv_array_clear(&array);
	return rc;
}

static int is_original_commit_empty(struct commit *commit)
{
	const unsigned char *ptree_sha1;

	if (parse_commit(commit))
		return error(_("Could not parse commit %s\n"),
			     oid_to_hex(&commit->object.oid));
	if (commit->parents) {
		struct commit *parent = commit->parents->item;
		if (parse_commit(parent))
			return error(_("Could not parse parent commit %s\n"),
				oid_to_hex(&parent->object.oid));
		ptree_sha1 = parent->tree->object.oid.hash;
	} else {
		ptree_sha1 = EMPTY_TREE_SHA1_BIN; /* commit is root */
	}

	return !hashcmp(ptree_sha1, commit->tree->object.oid.hash);
}

/*
 * Do we run "git commit" with "--allow-empty"?
 */
static int allow_empty(struct replay_opts *opts, struct commit *commit)
{
	int index_unchanged, empty_commit;

	/*
	 * Three cases:
	 *
	 * (1) we do not allow empty at all and error out.
	 *
	 * (2) we allow ones that were initially empty, but
	 * forbid the ones that become empty;
	 *
	 * (3) we allow both.
	 */
	if (!opts->allow_empty)
		return 0; /* let "git commit" barf as necessary */

	index_unchanged = is_index_unchanged();
	if (index_unchanged < 0)
		return index_unchanged;
	if (!index_unchanged)
		return 0; /* we do not have to say --allow-empty */

	if (opts->keep_redundant_commits)
		return 1;

	empty_commit = is_original_commit_empty(commit);
	if (empty_commit < 0)
		return empty_commit;
	if (!empty_commit)
		return 0;
	else
		return 1;
}

static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
{
	unsigned char head[20];
	struct commit *base, *next, *parent;
	const char *base_label, *next_label;
	struct commit_message msg = { NULL, NULL, NULL, NULL };
	struct strbuf msgbuf = STRBUF_INIT;
	int res, unborn = 0, allow;

	if (opts->no_commit) {
		/*
		 * We do not intend to commit immediately.  We just want to
		 * merge the differences in, so let's compute the tree
		 * that represents the "current" state for merge-recursive
		 * to work on.
		 */
		if (write_cache_as_tree(head, 0, NULL))
			die (_("Your index file is unmerged."));
	} else {
		unborn = get_sha1("HEAD", head);
		if (unborn)
			hashcpy(head, EMPTY_TREE_SHA1_BIN);
		if (index_differs_from(unborn ? EMPTY_TREE_SHA1_HEX : "HEAD", 0))
			return error_dirty_index(opts);
	}
	discard_cache();

	if (!commit->parents) {
		parent = NULL;
	}
	else if (commit->parents->next) {
		/* Reverting or cherry-picking a merge commit */
		int cnt;
		struct commit_list *p;

		if (!opts->mainline)
			return error(_("Commit %s is a merge but no -m option was given."),
				oid_to_hex(&commit->object.oid));

		for (cnt = 1, p = commit->parents;
		     cnt != opts->mainline && p;
		     cnt++)
			p = p->next;
		if (cnt != opts->mainline || !p)
			return error(_("Commit %s does not have parent %d"),
				oid_to_hex(&commit->object.oid), opts->mainline);
		parent = p->item;
	} else if (0 < opts->mainline)
		return error(_("Mainline was specified but commit %s is not a merge."),
			oid_to_hex(&commit->object.oid));
	else
		parent = commit->parents->item;

	if (opts->allow_ff &&
	    ((parent && !hashcmp(parent->object.oid.hash, head)) ||
	     (!parent && unborn)))
		return fast_forward_to(commit->object.oid.hash, head, unborn, opts);

	if (parent && parse_commit(parent) < 0)
		/* TRANSLATORS: The first %s will be "revert" or
		   "cherry-pick", the second %s a SHA1 */
		return error(_("%s: cannot parse parent commit %s"),
			action_name(opts), oid_to_hex(&parent->object.oid));

	if (get_message(commit, &msg) != 0)
		return error(_("Cannot get commit message for %s"),
			oid_to_hex(&commit->object.oid));

	/*
	 * "commit" is an existing commit.  We would want to apply
	 * the difference it introduces since its first parent "prev"
	 * on top of the current HEAD if we are cherry-pick.  Or the
	 * reverse of it if we are revert.
	 */

	if (opts->action == REPLAY_REVERT) {
		base = commit;
		base_label = msg.label;
		next = parent;
		next_label = msg.parent_label;
		strbuf_addstr(&msgbuf, "Revert \"");
		strbuf_addstr(&msgbuf, msg.subject);
		strbuf_addstr(&msgbuf, "\"\n\nThis reverts commit ");
		strbuf_addstr(&msgbuf, oid_to_hex(&commit->object.oid));

		if (commit->parents && commit->parents->next) {
			strbuf_addstr(&msgbuf, ", reversing\nchanges made to ");
			strbuf_addstr(&msgbuf, oid_to_hex(&parent->object.oid));
		}
		strbuf_addstr(&msgbuf, ".\n");
	} else {
		const char *p;

		base = parent;
		base_label = msg.parent_label;
		next = commit;
		next_label = msg.label;

		/*
		 * Append the commit log message to msgbuf; it starts
		 * after the tree, parent, author, committer
		 * information followed by "\n\n".
		 */
		p = strstr(msg.message, "\n\n");
		if (p) {
			p += 2;
			strbuf_addstr(&msgbuf, p);
		}

		if (opts->record_origin) {
			if (!has_conforming_footer(&msgbuf, NULL, 0))
				strbuf_addch(&msgbuf, '\n');
			strbuf_addstr(&msgbuf, cherry_picked_prefix);
			strbuf_addstr(&msgbuf, oid_to_hex(&commit->object.oid));
			strbuf_addstr(&msgbuf, ")\n");
		}
	}

	if (!opts->strategy || !strcmp(opts->strategy, "recursive") || opts->action == REPLAY_REVERT) {
		res = do_recursive_merge(base, next, base_label, next_label,
					 head, &msgbuf, opts);
		write_message(&msgbuf, git_path_merge_msg());
	} else {
		struct commit_list *common = NULL;
		struct commit_list *remotes = NULL;

		write_message(&msgbuf, git_path_merge_msg());

		commit_list_insert(base, &common);
		commit_list_insert(next, &remotes);
		res = try_merge_command(opts->strategy, opts->xopts_nr, opts->xopts,
					common, sha1_to_hex(head), remotes);
		free_commit_list(common);
		free_commit_list(remotes);
	}

	/*
	 * If the merge was clean or if it failed due to conflict, we write
	 * CHERRY_PICK_HEAD for the subsequent invocation of commit to use.
	 * However, if the merge did not even start, then we don't want to
	 * write it at all.
	 */
	if (opts->action == REPLAY_PICK && !opts->no_commit && (res == 0 || res == 1))
		update_ref(NULL, "CHERRY_PICK_HEAD", commit->object.oid.hash, NULL,
			   REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
	if (opts->action == REPLAY_REVERT && ((opts->no_commit && res == 0) || res == 1))
		update_ref(NULL, "REVERT_HEAD", commit->object.oid.hash, NULL,
			   REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);

	if (res) {
		error(opts->action == REPLAY_REVERT
		      ? _("could not revert %s... %s")
		      : _("could not apply %s... %s"),
		      find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV),
		      msg.subject);
		print_advice(res == 1, opts);
		rerere(opts->allow_rerere_auto);
		goto leave;
	}

	allow = allow_empty(opts, commit);
	if (allow < 0) {
		res = allow;
		goto leave;
	}
	if (!opts->no_commit)
		res = run_git_commit(git_path_merge_msg(), opts, allow);

leave:
	free_message(commit, &msg);

	return res;
}

static void prepare_revs(struct replay_opts *opts)
{
	/*
	 * picking (but not reverting) ranges (but not individual revisions)
	 * should be done in reverse
	 */
	if (opts->action == REPLAY_PICK && !opts->revs->no_walk)
		opts->revs->reverse ^= 1;

	if (prepare_revision_walk(opts->revs))
		die(_("revision walk setup failed"));

	if (!opts->revs->commits)
		die(_("empty commit set passed"));
}

static void read_and_refresh_cache(struct replay_opts *opts)
{
	static struct lock_file index_lock;
	int index_fd = hold_locked_index(&index_lock, 0);
	if (read_index_preload(&the_index, NULL) < 0)
		die(_("git %s: failed to read the index"), action_name(opts));
	refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL, NULL);
	if (the_index.cache_changed && index_fd >= 0) {
		if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
			die(_("git %s: failed to refresh the index"), action_name(opts));
	}
	rollback_lock_file(&index_lock);
}

static int format_todo(struct strbuf *buf, struct commit_list *todo_list,
		struct replay_opts *opts)
{
	struct commit_list *cur = NULL;
	const char *sha1_abbrev = NULL;
	const char *action_str = opts->action == REPLAY_REVERT ? "revert" : "pick";
	const char *subject;
	int subject_len;

	for (cur = todo_list; cur; cur = cur->next) {
		const char *commit_buffer = get_commit_buffer(cur->item, NULL);
		sha1_abbrev = find_unique_abbrev(cur->item->object.oid.hash, DEFAULT_ABBREV);
		subject_len = find_commit_subject(commit_buffer, &subject);
		strbuf_addf(buf, "%s %s %.*s\n", action_str, sha1_abbrev,
			subject_len, subject);
		unuse_commit_buffer(cur->item, commit_buffer);
	}
	return 0;
}

static struct commit *parse_insn_line(char *bol, char *eol, struct replay_opts *opts)
{
	unsigned char commit_sha1[20];
	enum replay_action action;
	char *end_of_object_name;
	int saved, status, padding;

	if (starts_with(bol, "pick")) {
		action = REPLAY_PICK;
		bol += strlen("pick");
	} else if (starts_with(bol, "revert")) {
		action = REPLAY_REVERT;
		bol += strlen("revert");
	} else
		return NULL;

	/* Eat up extra spaces/ tabs before object name */
	padding = strspn(bol, " \t");
	if (!padding)
		return NULL;
	bol += padding;

	end_of_object_name = bol + strcspn(bol, " \t\n");
	saved = *end_of_object_name;
	*end_of_object_name = '\0';
	status = get_sha1(bol, commit_sha1);
	*end_of_object_name = saved;

	/*
	 * Verify that the action matches up with the one in
	 * opts; we don't support arbitrary instructions
	 */
	if (action != opts->action) {
		const char *action_str;
		action_str = action == REPLAY_REVERT ? "revert" : "cherry-pick";
		error(_("Cannot %s during a %s"), action_str, action_name(opts));
		return NULL;
	}

	if (status < 0)
		return NULL;

	return lookup_commit_reference(commit_sha1);
}

static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
			struct replay_opts *opts)
{
	struct commit_list **next = todo_list;
	struct commit *commit;
	char *p = buf;
	int i;

	for (i = 1; *p; i++) {
		char *eol = strchrnul(p, '\n');
		commit = parse_insn_line(p, eol, opts);
		if (!commit)
			return error(_("Could not parse line %d."), i);
		next = commit_list_append(commit, next);
		p = *eol ? eol + 1 : eol;
	}
	if (!*todo_list)
		return error(_("No commits parsed."));
	return 0;
}

static void read_populate_todo(struct commit_list **todo_list,
			struct replay_opts *opts)
{
	struct strbuf buf = STRBUF_INIT;
	int fd, res;

	fd = open(git_path_todo_file(), O_RDONLY);
	if (fd < 0)
		die_errno(_("Could not open %s"), git_path_todo_file());
	if (strbuf_read(&buf, fd, 0) < 0) {
		close(fd);
		strbuf_release(&buf);
		die(_("Could not read %s."), git_path_todo_file());
	}
	close(fd);

	res = parse_insn_buffer(buf.buf, todo_list, opts);
	strbuf_release(&buf);
	if (res)
		die(_("Unusable instruction sheet: %s"), git_path_todo_file());
}

static int populate_opts_cb(const char *key, const char *value, void *data)
{
	struct replay_opts *opts = data;
	int error_flag = 1;

	if (!value)
		error_flag = 0;
	else if (!strcmp(key, "options.no-commit"))
		opts->no_commit = git_config_bool_or_int(key, value, &error_flag);
	else if (!strcmp(key, "options.edit"))
		opts->edit = git_config_bool_or_int(key, value, &error_flag);
	else if (!strcmp(key, "options.signoff"))
		opts->signoff = git_config_bool_or_int(key, value, &error_flag);
	else if (!strcmp(key, "options.record-origin"))
		opts->record_origin = git_config_bool_or_int(key, value, &error_flag);
	else if (!strcmp(key, "options.allow-ff"))
		opts->allow_ff = git_config_bool_or_int(key, value, &error_flag);
	else if (!strcmp(key, "options.mainline"))
		opts->mainline = git_config_int(key, value);
	else if (!strcmp(key, "options.strategy"))
		git_config_string(&opts->strategy, key, value);
	else if (!strcmp(key, "options.gpg-sign"))
		git_config_string(&opts->gpg_sign, key, value);
	else if (!strcmp(key, "options.strategy-option")) {
		ALLOC_GROW(opts->xopts, opts->xopts_nr + 1, opts->xopts_alloc);
		opts->xopts[opts->xopts_nr++] = xstrdup(value);
	} else
		return error(_("Invalid key: %s"), key);

	if (!error_flag)
		return error(_("Invalid value for %s: %s"), key, value);

	return 0;
}

static void read_populate_opts(struct replay_opts **opts_ptr)
{
	if (!file_exists(git_path_opts_file()))
		return;
	if (git_config_from_file(populate_opts_cb, git_path_opts_file(), *opts_ptr) < 0)
		die(_("Malformed options sheet: %s"), git_path_opts_file());
}

static void walk_revs_populate_todo(struct commit_list **todo_list,
				struct replay_opts *opts)
{
	struct commit *commit;
	struct commit_list **next;

	prepare_revs(opts);

	next = todo_list;
	while ((commit = get_revision(opts->revs)))
		next = commit_list_append(commit, next);
}

static int create_seq_dir(void)
{
	if (file_exists(git_path_seq_dir())) {
		error(_("a cherry-pick or revert is already in progress"));
		advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
		return -1;
	}
	else if (mkdir(git_path_seq_dir(), 0777) < 0)
		die_errno(_("Could not create sequencer directory %s"),
			  git_path_seq_dir());
	return 0;
}

static void save_head(const char *head)
{
	static struct lock_file head_lock;
	struct strbuf buf = STRBUF_INIT;
	int fd;

	fd = hold_lock_file_for_update(&head_lock, git_path_head_file(), LOCK_DIE_ON_ERROR);
	strbuf_addf(&buf, "%s\n", head);
	if (write_in_full(fd, buf.buf, buf.len) < 0)
		die_errno(_("Could not write to %s"), git_path_head_file());
	if (commit_lock_file(&head_lock) < 0)
		die(_("Error wrapping up %s."), git_path_head_file());
}

static int reset_for_rollback(const unsigned char *sha1)
{
	const char *argv[4];	/* reset --merge <arg> + NULL */
	argv[0] = "reset";
	argv[1] = "--merge";
	argv[2] = sha1_to_hex(sha1);
	argv[3] = NULL;
	return run_command_v_opt(argv, RUN_GIT_CMD);
}

static int rollback_single_pick(void)
{
	unsigned char head_sha1[20];

	if (!file_exists(git_path_cherry_pick_head()) &&
	    !file_exists(git_path_revert_head()))
		return error(_("no cherry-pick or revert in progress"));
	if (read_ref_full("HEAD", 0, head_sha1, NULL))
		return error(_("cannot resolve HEAD"));
	if (is_null_sha1(head_sha1))
		return error(_("cannot abort from a branch yet to be born"));
	return reset_for_rollback(head_sha1);
}

static int sequencer_rollback(struct replay_opts *opts)
{
	FILE *f;
	unsigned char sha1[20];
	struct strbuf buf = STRBUF_INIT;

	f = fopen(git_path_head_file(), "r");
	if (!f && errno == ENOENT) {
		/*
		 * There is no multiple-cherry-pick in progress.
		 * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
		 * a single-cherry-pick in progress, abort that.
		 */
		return rollback_single_pick();
	}
	if (!f)
		return error_errno(_("cannot open %s"), git_path_head_file());
	if (strbuf_getline_lf(&buf, f)) {
		error(_("cannot read %s: %s"), git_path_head_file(),
		      ferror(f) ?  strerror(errno) : _("unexpected end of file"));
		fclose(f);
		goto fail;
	}
	fclose(f);
	if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
		error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
			git_path_head_file());
		goto fail;
	}
	if (is_null_sha1(sha1)) {
		error(_("cannot abort from a branch yet to be born"));
		goto fail;
	}
	if (reset_for_rollback(sha1))
		goto fail;
	remove_sequencer_state();
	strbuf_release(&buf);
	return 0;
fail:
	strbuf_release(&buf);
	return -1;
}

static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
{
	static struct lock_file todo_lock;
	struct strbuf buf = STRBUF_INIT;
	int fd;

	fd = hold_lock_file_for_update(&todo_lock, git_path_todo_file(), LOCK_DIE_ON_ERROR);
	if (format_todo(&buf, todo_list, opts) < 0)
		die(_("Could not format %s."), git_path_todo_file());
	if (write_in_full(fd, buf.buf, buf.len) < 0) {
		strbuf_release(&buf);
		die_errno(_("Could not write to %s"), git_path_todo_file());
	}
	if (commit_lock_file(&todo_lock) < 0) {
		strbuf_release(&buf);
		die(_("Error wrapping up %s."), git_path_todo_file());
	}
	strbuf_release(&buf);
}

static void save_opts(struct replay_opts *opts)
{
	const char *opts_file = git_path_opts_file();

	if (opts->no_commit)
		git_config_set_in_file(opts_file, "options.no-commit", "true");
	if (opts->edit)
		git_config_set_in_file(opts_file, "options.edit", "true");
	if (opts->signoff)
		git_config_set_in_file(opts_file, "options.signoff", "true");
	if (opts->record_origin)
		git_config_set_in_file(opts_file, "options.record-origin", "true");
	if (opts->allow_ff)
		git_config_set_in_file(opts_file, "options.allow-ff", "true");
	if (opts->mainline) {
		struct strbuf buf = STRBUF_INIT;
		strbuf_addf(&buf, "%d", opts->mainline);
		git_config_set_in_file(opts_file, "options.mainline", buf.buf);
		strbuf_release(&buf);
	}
	if (opts->strategy)
		git_config_set_in_file(opts_file, "options.strategy", opts->strategy);
	if (opts->gpg_sign)
		git_config_set_in_file(opts_file, "options.gpg-sign", opts->gpg_sign);
	if (opts->xopts) {
		int i;
		for (i = 0; i < opts->xopts_nr; i++)
			git_config_set_multivar_in_file(opts_file,
							"options.strategy-option",
							opts->xopts[i], "^$", 0);
	}
}

static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
{
	struct commit_list *cur;
	int res;

	setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
	if (opts->allow_ff)
		assert(!(opts->signoff || opts->no_commit ||
				opts->record_origin || opts->edit));
	read_and_refresh_cache(opts);

	for (cur = todo_list; cur; cur = cur->next) {
		save_todo(cur, opts);
		res = do_pick_commit(cur->item, opts);
		if (res)
			return res;
	}

	/*
	 * Sequence of picks finished successfully; cleanup by
	 * removing the .git/sequencer directory
	 */
	remove_sequencer_state();
	return 0;
}

static int continue_single_pick(void)
{
	const char *argv[] = { "commit", NULL };

	if (!file_exists(git_path_cherry_pick_head()) &&
	    !file_exists(git_path_revert_head()))
		return error(_("no cherry-pick or revert in progress"));
	return run_command_v_opt(argv, RUN_GIT_CMD);
}

static int sequencer_continue(struct replay_opts *opts)
{
	struct commit_list *todo_list = NULL;

	if (!file_exists(git_path_todo_file()))
		return continue_single_pick();
	read_populate_opts(&opts);
	read_populate_todo(&todo_list, opts);

	/* Verify that the conflict has been resolved */
	if (file_exists(git_path_cherry_pick_head()) ||
	    file_exists(git_path_revert_head())) {
		int ret = continue_single_pick();
		if (ret)
			return ret;
	}
	if (index_differs_from("HEAD", 0))
		return error_dirty_index(opts);
	todo_list = todo_list->next;
	return pick_commits(todo_list, opts);
}

static int single_pick(struct commit *cmit, struct replay_opts *opts)
{
	setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
	return do_pick_commit(cmit, opts);
}

int sequencer_pick_revisions(struct replay_opts *opts)
{
	struct commit_list *todo_list = NULL;
	unsigned char sha1[20];
	int i;

	if (opts->subcommand == REPLAY_NONE)
		assert(opts->revs);

	read_and_refresh_cache(opts);

	/*
	 * Decide what to do depending on the arguments; a fresh
	 * cherry-pick should be handled differently from an existing
	 * one that is being continued
	 */
	if (opts->subcommand == REPLAY_REMOVE_STATE) {
		remove_sequencer_state();
		return 0;
	}
	if (opts->subcommand == REPLAY_ROLLBACK)
		return sequencer_rollback(opts);
	if (opts->subcommand == REPLAY_CONTINUE)
		return sequencer_continue(opts);

	for (i = 0; i < opts->revs->pending.nr; i++) {
		unsigned char sha1[20];
		const char *name = opts->revs->pending.objects[i].name;

		/* This happens when using --stdin. */
		if (!strlen(name))
			continue;

		if (!get_sha1(name, sha1)) {
			if (!lookup_commit_reference_gently(sha1, 1)) {
				enum object_type type = sha1_object_info(sha1, NULL);
				die(_("%s: can't cherry-pick a %s"), name, typename(type));
			}
		} else
			die(_("%s: bad revision"), name);
	}

	/*
	 * If we were called as "git cherry-pick <commit>", just
	 * cherry-pick/revert it, set CHERRY_PICK_HEAD /
	 * REVERT_HEAD, and don't touch the sequencer state.
	 * This means it is possible to cherry-pick in the middle
	 * of a cherry-pick sequence.
	 */
	if (opts->revs->cmdline.nr == 1 &&
	    opts->revs->cmdline.rev->whence == REV_CMD_REV &&
	    opts->revs->no_walk &&
	    !opts->revs->cmdline.rev->flags) {
		struct commit *cmit;
		if (prepare_revision_walk(opts->revs))
			die(_("revision walk setup failed"));
		cmit = get_revision(opts->revs);
		if (!cmit || get_revision(opts->revs))
			die("BUG: expected exactly one commit from walk");
		return single_pick(cmit, opts);
	}

	/*
	 * Start a new cherry-pick/ revert sequence; but
	 * first, make sure that an existing one isn't in
	 * progress
	 */

	walk_revs_populate_todo(&todo_list, opts);
	if (create_seq_dir() < 0)
		return -1;
	if (get_sha1("HEAD", sha1) && (opts->action == REPLAY_REVERT))
		return error(_("Can't revert as initial commit"));
	save_head(sha1_to_hex(sha1));
	save_opts(opts);
	return pick_commits(todo_list, opts);
}

void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
{
	unsigned no_dup_sob = flag & APPEND_SIGNOFF_DEDUP;
	struct strbuf sob = STRBUF_INIT;
	int has_footer;

	strbuf_addstr(&sob, sign_off_header);
	strbuf_addstr(&sob, fmt_name(getenv("GIT_COMMITTER_NAME"),
				getenv("GIT_COMMITTER_EMAIL")));
	strbuf_addch(&sob, '\n');

	/*
	 * If the whole message buffer is equal to the sob, pretend that we
	 * found a conforming footer with a matching sob
	 */
	if (msgbuf->len - ignore_footer == sob.len &&
	    !strncmp(msgbuf->buf, sob.buf, sob.len))
		has_footer = 3;
	else
		has_footer = has_conforming_footer(msgbuf, &sob, ignore_footer);

	if (!has_footer) {
		const char *append_newlines = NULL;
		size_t len = msgbuf->len - ignore_footer;

		if (!len) {
			/*
			 * The buffer is completely empty.  Leave foom for
			 * the title and body to be filled in by the user.
			 */
			append_newlines = "\n\n";
		} else if (msgbuf->buf[len - 1] != '\n') {
			/*
			 * Incomplete line.  Complete the line and add a
			 * blank one so that there is an empty line between
			 * the message body and the sob.
			 */
			append_newlines = "\n\n";
		} else if (len == 1) {
			/*
			 * Buffer contains a single newline.  Add another
			 * so that we leave room for the title and body.
			 */
			append_newlines = "\n";
		} else if (msgbuf->buf[len - 2] != '\n') {
			/*
			 * Buffer ends with a single newline.  Add another
			 * so that there is an empty line between the message
			 * body and the sob.
			 */
			append_newlines = "\n";
		} /* else, the buffer already ends with two newlines. */

		if (append_newlines)
			strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0,
				append_newlines, strlen(append_newlines));
	}

	if (has_footer != 3 && (!no_dup_sob || has_footer != 2))
		strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0,
				sob.buf, sob.len);

	strbuf_release(&sob);
}