summaryrefslogtreecommitdiff
path: root/submodule.c
blob: 09a41b59befca75feb6fec95d6c98bb51e10b987 (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
#include "cache.h"
#include "submodule.h"
#include "dir.h"
#include "diff.h"
#include "commit.h"
#include "revision.h"
#include "run-command.h"
#include "diffcore.h"
#include "refs.h"
#include "string-list.h"
#include "sha1-array.h"
#include "argv-array.h"

static struct string_list config_name_for_path;
static struct string_list config_fetch_recurse_submodules_for_name;
static struct string_list config_ignore_for_name;
static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
static struct string_list changed_submodule_paths;
static int initialized_fetch_ref_tips;
static struct sha1_array ref_tips_before_fetch;
static struct sha1_array ref_tips_after_fetch;

/*
 * The following flag is set if the .gitmodules file is unmerged. We then
 * disable recursion for all submodules where .git/config doesn't have a
 * matching config entry because we can't guess what might be configured in
 * .gitmodules unless the user resolves the conflict. When a command line
 * option is given (which always overrides configuration) this flag will be
 * ignored.
 */
static int gitmodules_is_unmerged;

static int add_submodule_odb(const char *path)
{
	struct strbuf objects_directory = STRBUF_INIT;
	struct alternate_object_database *alt_odb;
	int ret = 0;
	const char *git_dir;

	strbuf_addf(&objects_directory, "%s/.git", path);
	git_dir = read_gitfile(objects_directory.buf);
	if (git_dir) {
		strbuf_reset(&objects_directory);
		strbuf_addstr(&objects_directory, git_dir);
	}
	strbuf_addstr(&objects_directory, "/objects/");
	if (!is_directory(objects_directory.buf)) {
		ret = -1;
		goto done;
	}
	/* avoid adding it twice */
	for (alt_odb = alt_odb_list; alt_odb; alt_odb = alt_odb->next)
		if (alt_odb->name - alt_odb->base == objects_directory.len &&
				!strncmp(alt_odb->base, objects_directory.buf,
					objects_directory.len))
			goto done;

	alt_odb = xmalloc(objects_directory.len + 42 + sizeof(*alt_odb));
	alt_odb->next = alt_odb_list;
	strcpy(alt_odb->base, objects_directory.buf);
	alt_odb->name = alt_odb->base + objects_directory.len;
	alt_odb->name[2] = '/';
	alt_odb->name[40] = '\0';
	alt_odb->name[41] = '\0';
	alt_odb_list = alt_odb;
	prepare_alt_odb();
done:
	strbuf_release(&objects_directory);
	return ret;
}

void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
					     const char *path)
{
	struct string_list_item *path_option, *ignore_option;
	path_option = unsorted_string_list_lookup(&config_name_for_path, path);
	if (path_option) {
		ignore_option = unsorted_string_list_lookup(&config_ignore_for_name, path_option->util);
		if (ignore_option)
			handle_ignore_submodules_arg(diffopt, ignore_option->util);
		else if (gitmodules_is_unmerged)
			DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
	}
}

int submodule_config(const char *var, const char *value, void *cb)
{
	if (!prefixcmp(var, "submodule."))
		return parse_submodule_config_option(var, value);
	else if (!strcmp(var, "fetch.recursesubmodules")) {
		config_fetch_recurse_submodules = parse_fetch_recurse_submodules_arg(var, value);
		return 0;
	}
	return 0;
}

void gitmodules_config(void)
{
	const char *work_tree = get_git_work_tree();
	if (work_tree) {
		struct strbuf gitmodules_path = STRBUF_INIT;
		int pos;
		strbuf_addstr(&gitmodules_path, work_tree);
		strbuf_addstr(&gitmodules_path, "/.gitmodules");
		if (read_cache() < 0)
			die("index file corrupt");
		pos = cache_name_pos(".gitmodules", 11);
		if (pos < 0) { /* .gitmodules not found or isn't merged */
			pos = -1 - pos;
			if (active_nr > pos) {  /* there is a .gitmodules */
				const struct cache_entry *ce = active_cache[pos];
				if (ce_namelen(ce) == 11 &&
				    !memcmp(ce->name, ".gitmodules", 11))
					gitmodules_is_unmerged = 1;
			}
		}

		if (!gitmodules_is_unmerged)
			git_config_from_file(submodule_config, gitmodules_path.buf, NULL);
		strbuf_release(&gitmodules_path);
	}
}

int parse_submodule_config_option(const char *var, const char *value)
{
	int len;
	struct string_list_item *config;
	struct strbuf submodname = STRBUF_INIT;

	var += 10;		/* Skip "submodule." */

	len = strlen(var);
	if ((len > 5) && !strcmp(var + len - 5, ".path")) {
		strbuf_add(&submodname, var, len - 5);
		config = unsorted_string_list_lookup(&config_name_for_path, value);
		if (config)
			free(config->util);
		else
			config = string_list_append(&config_name_for_path, xstrdup(value));
		config->util = strbuf_detach(&submodname, NULL);
		strbuf_release(&submodname);
	} else if ((len > 23) && !strcmp(var + len - 23, ".fetchrecursesubmodules")) {
		strbuf_add(&submodname, var, len - 23);
		config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
		if (!config)
			config = string_list_append(&config_fetch_recurse_submodules_for_name,
						    strbuf_detach(&submodname, NULL));
		config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
		strbuf_release(&submodname);
	} else if ((len > 7) && !strcmp(var + len - 7, ".ignore")) {
		if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
		    strcmp(value, "all") && strcmp(value, "none")) {
			warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
			return 0;
		}

		strbuf_add(&submodname, var, len - 7);
		config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
		if (config)
			free(config->util);
		else
			config = string_list_append(&config_ignore_for_name,
						    strbuf_detach(&submodname, NULL));
		strbuf_release(&submodname);
		config->util = xstrdup(value);
		return 0;
	}
	return 0;
}

void handle_ignore_submodules_arg(struct diff_options *diffopt,
				  const char *arg)
{
	DIFF_OPT_CLR(diffopt, IGNORE_SUBMODULES);
	DIFF_OPT_CLR(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
	DIFF_OPT_CLR(diffopt, IGNORE_DIRTY_SUBMODULES);

	if (!strcmp(arg, "all"))
		DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
	else if (!strcmp(arg, "untracked"))
		DIFF_OPT_SET(diffopt, IGNORE_UNTRACKED_IN_SUBMODULES);
	else if (!strcmp(arg, "dirty"))
		DIFF_OPT_SET(diffopt, IGNORE_DIRTY_SUBMODULES);
	else if (strcmp(arg, "none"))
		die("bad --ignore-submodules argument: %s", arg);
}

static int prepare_submodule_summary(struct rev_info *rev, const char *path,
		struct commit *left, struct commit *right,
		int *fast_forward, int *fast_backward)
{
	struct commit_list *merge_bases, *list;

	init_revisions(rev, NULL);
	setup_revisions(0, NULL, rev, NULL);
	rev->left_right = 1;
	rev->first_parent_only = 1;
	left->object.flags |= SYMMETRIC_LEFT;
	add_pending_object(rev, &left->object, path);
	add_pending_object(rev, &right->object, path);
	merge_bases = get_merge_bases(left, right, 1);
	if (merge_bases) {
		if (merge_bases->item == left)
			*fast_forward = 1;
		else if (merge_bases->item == right)
			*fast_backward = 1;
	}
	for (list = merge_bases; list; list = list->next) {
		list->item->object.flags |= UNINTERESTING;
		add_pending_object(rev, &list->item->object,
			sha1_to_hex(list->item->object.sha1));
	}
	return prepare_revision_walk(rev);
}

static void print_submodule_summary(struct rev_info *rev, FILE *f,
		const char *del, const char *add, const char *reset)
{
	static const char format[] = "  %m %s";
	struct strbuf sb = STRBUF_INIT;
	struct commit *commit;

	while ((commit = get_revision(rev))) {
		struct pretty_print_context ctx = {0};
		ctx.date_mode = rev->date_mode;
		strbuf_setlen(&sb, 0);
		if (commit->object.flags & SYMMETRIC_LEFT) {
			if (del)
				strbuf_addstr(&sb, del);
		}
		else if (add)
			strbuf_addstr(&sb, add);
		format_commit_message(commit, format, &sb, &ctx);
		if (reset)
			strbuf_addstr(&sb, reset);
		strbuf_addch(&sb, '\n');
		fprintf(f, "%s", sb.buf);
	}
	strbuf_release(&sb);
}

int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg)
{
	switch (git_config_maybe_bool(opt, arg)) {
	case 1:
		return RECURSE_SUBMODULES_ON;
	case 0:
		return RECURSE_SUBMODULES_OFF;
	default:
		if (!strcmp(arg, "on-demand"))
			return RECURSE_SUBMODULES_ON_DEMAND;
		die("bad %s argument: %s", opt, arg);
	}
}

void show_submodule_summary(FILE *f, const char *path,
		unsigned char one[20], unsigned char two[20],
		unsigned dirty_submodule,
		const char *del, const char *add, const char *reset)
{
	struct rev_info rev;
	struct commit *left = left, *right = right;
	const char *message = NULL;
	struct strbuf sb = STRBUF_INIT;
	int fast_forward = 0, fast_backward = 0;

	if (is_null_sha1(two))
		message = "(submodule deleted)";
	else if (add_submodule_odb(path))
		message = "(not checked out)";
	else if (is_null_sha1(one))
		message = "(new submodule)";
	else if (!(left = lookup_commit_reference(one)) ||
		 !(right = lookup_commit_reference(two)))
		message = "(commits not present)";

	if (!message &&
	    prepare_submodule_summary(&rev, path, left, right,
					&fast_forward, &fast_backward))
		message = "(revision walker failed)";

	if (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED)
		fprintf(f, "Submodule %s contains untracked content\n", path);
	if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
		fprintf(f, "Submodule %s contains modified content\n", path);

	if (!hashcmp(one, two)) {
		strbuf_release(&sb);
		return;
	}

	strbuf_addf(&sb, "Submodule %s %s..", path,
			find_unique_abbrev(one, DEFAULT_ABBREV));
	if (!fast_backward && !fast_forward)
		strbuf_addch(&sb, '.');
	strbuf_addf(&sb, "%s", find_unique_abbrev(two, DEFAULT_ABBREV));
	if (message)
		strbuf_addf(&sb, " %s\n", message);
	else
		strbuf_addf(&sb, "%s:\n", fast_backward ? " (rewind)" : "");
	fwrite(sb.buf, sb.len, 1, f);

	if (!message) {
		print_submodule_summary(&rev, f, del, add, reset);
		clear_commit_marks(left, ~0);
		clear_commit_marks(right, ~0);
	}

	strbuf_release(&sb);
}

void set_config_fetch_recurse_submodules(int value)
{
	config_fetch_recurse_submodules = value;
}

static int has_remote(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
{
	return 1;
}

static int submodule_needs_pushing(const char *path, const unsigned char sha1[20])
{
	if (add_submodule_odb(path) || !lookup_commit_reference(sha1))
		return 0;

	if (for_each_remote_ref_submodule(path, has_remote, NULL) > 0) {
		struct child_process cp;
		const char *argv[] = {"rev-list", NULL, "--not", "--remotes", "-n", "1" , NULL};
		struct strbuf buf = STRBUF_INIT;
		int needs_pushing = 0;

		argv[1] = sha1_to_hex(sha1);
		memset(&cp, 0, sizeof(cp));
		cp.argv = argv;
		cp.env = local_repo_env;
		cp.git_cmd = 1;
		cp.no_stdin = 1;
		cp.out = -1;
		cp.dir = path;
		if (start_command(&cp))
			die("Could not run 'git rev-list %s --not --remotes -n 1' command in submodule %s",
				sha1_to_hex(sha1), path);
		if (strbuf_read(&buf, cp.out, 41))
			needs_pushing = 1;
		finish_command(&cp);
		close(cp.out);
		strbuf_release(&buf);
		return needs_pushing;
	}

	return 0;
}

static void collect_submodules_from_diff(struct diff_queue_struct *q,
					 struct diff_options *options,
					 void *data)
{
	int i;
	int *needs_pushing = data;

	for (i = 0; i < q->nr; i++) {
		struct diff_filepair *p = q->queue[i];
		if (!S_ISGITLINK(p->two->mode))
			continue;
		if (submodule_needs_pushing(p->two->path, p->two->sha1)) {
			*needs_pushing = 1;
			break;
		}
	}
}


static void commit_need_pushing(struct commit *commit, struct commit_list *parent, int *needs_pushing)
{
	const unsigned char (*parents)[20];
	unsigned int i, n;
	struct rev_info rev;

	n = commit_list_count(parent);
	parents = xmalloc(n * sizeof(*parents));

	for (i = 0; i < n; i++) {
		hashcpy((unsigned char *)(parents + i), parent->item->object.sha1);
		parent = parent->next;
	}

	init_revisions(&rev, NULL);
	rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
	rev.diffopt.format_callback = collect_submodules_from_diff;
	rev.diffopt.format_callback_data = needs_pushing;
	diff_tree_combined(commit->object.sha1, parents, n, 1, &rev);

	free((void *)parents);
}

int check_submodule_needs_pushing(unsigned char new_sha1[20], const char *remotes_name)
{
	struct rev_info rev;
	struct commit *commit;
	const char *argv[] = {NULL, NULL, "--not", "NULL", NULL};
	int argc = ARRAY_SIZE(argv) - 1;
	char *sha1_copy;
	int needs_pushing = 0;
	struct strbuf remotes_arg = STRBUF_INIT;

	strbuf_addf(&remotes_arg, "--remotes=%s", remotes_name);
	init_revisions(&rev, NULL);
	sha1_copy = xstrdup(sha1_to_hex(new_sha1));
	argv[1] = sha1_copy;
	argv[3] = remotes_arg.buf;
	setup_revisions(argc, argv, &rev, NULL);
	if (prepare_revision_walk(&rev))
		die("revision walk setup failed");

	while ((commit = get_revision(&rev)) && !needs_pushing)
		commit_need_pushing(commit, commit->parents, &needs_pushing);

	free(sha1_copy);
	strbuf_release(&remotes_arg);

	return needs_pushing;
}

static int is_submodule_commit_present(const char *path, unsigned char sha1[20])
{
	int is_present = 0;
	if (!add_submodule_odb(path) && lookup_commit_reference(sha1)) {
		/* Even if the submodule is checked out and the commit is
		 * present, make sure it is reachable from a ref. */
		struct child_process cp;
		const char *argv[] = {"rev-list", "-n", "1", NULL, "--not", "--all", NULL};
		struct strbuf buf = STRBUF_INIT;

		argv[3] = sha1_to_hex(sha1);
		memset(&cp, 0, sizeof(cp));
		cp.argv = argv;
		cp.env = local_repo_env;
		cp.git_cmd = 1;
		cp.no_stdin = 1;
		cp.out = -1;
		cp.dir = path;
		if (!run_command(&cp) && !strbuf_read(&buf, cp.out, 1024))
			is_present = 1;

		close(cp.out);
		strbuf_release(&buf);
	}
	return is_present;
}

static void submodule_collect_changed_cb(struct diff_queue_struct *q,
					 struct diff_options *options,
					 void *data)
{
	int i;
	for (i = 0; i < q->nr; i++) {
		struct diff_filepair *p = q->queue[i];
		if (!S_ISGITLINK(p->two->mode))
			continue;

		if (S_ISGITLINK(p->one->mode)) {
			/* NEEDSWORK: We should honor the name configured in
			 * the .gitmodules file of the commit we are examining
			 * here to be able to correctly follow submodules
			 * being moved around. */
			struct string_list_item *path;
			path = unsorted_string_list_lookup(&changed_submodule_paths, p->two->path);
			if (!path && !is_submodule_commit_present(p->two->path, p->two->sha1))
				string_list_append(&changed_submodule_paths, xstrdup(p->two->path));
		} else {
			/* Submodule is new or was moved here */
			/* NEEDSWORK: When the .git directories of submodules
			 * live inside the superprojects .git directory some
			 * day we should fetch new submodules directly into
			 * that location too when config or options request
			 * that so they can be checked out from there. */
			continue;
		}
	}
}

static int add_sha1_to_array(const char *ref, const unsigned char *sha1,
			     int flags, void *data)
{
	sha1_array_append(data, sha1);
	return 0;
}

void check_for_new_submodule_commits(unsigned char new_sha1[20])
{
	if (!initialized_fetch_ref_tips) {
		for_each_ref(add_sha1_to_array, &ref_tips_before_fetch);
		initialized_fetch_ref_tips = 1;
	}

	sha1_array_append(&ref_tips_after_fetch, new_sha1);
}

static void add_sha1_to_argv(const unsigned char sha1[20], void *data)
{
	argv_array_push(data, sha1_to_hex(sha1));
}

static void calculate_changed_submodule_paths(void)
{
	struct rev_info rev;
	struct commit *commit;
	struct argv_array argv = ARGV_ARRAY_INIT;

	/* No need to check if there are no submodules configured */
	if (!config_name_for_path.nr)
		return;

	init_revisions(&rev, NULL);
	argv_array_push(&argv, "--"); /* argv[0] program name */
	sha1_array_for_each_unique(&ref_tips_after_fetch,
				   add_sha1_to_argv, &argv);
	argv_array_push(&argv, "--not");
	sha1_array_for_each_unique(&ref_tips_before_fetch,
				   add_sha1_to_argv, &argv);
	setup_revisions(argv.argc, argv.argv, &rev, NULL);
	if (prepare_revision_walk(&rev))
		die("revision walk setup failed");

	/*
	 * Collect all submodules (whether checked out or not) for which new
	 * commits have been recorded upstream in "changed_submodule_paths".
	 */
	while ((commit = get_revision(&rev))) {
		struct commit_list *parent = commit->parents;
		while (parent) {
			struct diff_options diff_opts;
			diff_setup(&diff_opts);
			DIFF_OPT_SET(&diff_opts, RECURSIVE);
			diff_opts.output_format |= DIFF_FORMAT_CALLBACK;
			diff_opts.format_callback = submodule_collect_changed_cb;
			if (diff_setup_done(&diff_opts) < 0)
				die("diff_setup_done failed");
			diff_tree_sha1(parent->item->object.sha1, commit->object.sha1, "", &diff_opts);
			diffcore_std(&diff_opts);
			diff_flush(&diff_opts);
			parent = parent->next;
		}
	}

	argv_array_clear(&argv);
	sha1_array_clear(&ref_tips_before_fetch);
	sha1_array_clear(&ref_tips_after_fetch);
	initialized_fetch_ref_tips = 0;
}

int fetch_populated_submodules(int num_options, const char **options,
			       const char *prefix, int command_line_option,
			       int quiet)
{
	int i, result = 0, argc = 0, default_argc;
	struct child_process cp;
	const char **argv;
	struct string_list_item *name_for_path;
	const char *work_tree = get_git_work_tree();
	if (!work_tree)
		goto out;

	if (!the_index.initialized)
		if (read_cache() < 0)
			die("index file corrupt");

	/* 6: "fetch" (options) --recurse-submodules-default default "--submodule-prefix" prefix NULL */
	argv = xcalloc(num_options + 6, sizeof(const char *));
	argv[argc++] = "fetch";
	for (i = 0; i < num_options; i++)
		argv[argc++] = options[i];
	argv[argc++] = "--recurse-submodules-default";
	default_argc = argc++;
	argv[argc++] = "--submodule-prefix";

	memset(&cp, 0, sizeof(cp));
	cp.argv = argv;
	cp.env = local_repo_env;
	cp.git_cmd = 1;
	cp.no_stdin = 1;

	calculate_changed_submodule_paths();

	for (i = 0; i < active_nr; i++) {
		struct strbuf submodule_path = STRBUF_INIT;
		struct strbuf submodule_git_dir = STRBUF_INIT;
		struct strbuf submodule_prefix = STRBUF_INIT;
		struct cache_entry *ce = active_cache[i];
		const char *git_dir, *name, *default_argv;

		if (!S_ISGITLINK(ce->ce_mode))
			continue;

		name = ce->name;
		name_for_path = unsorted_string_list_lookup(&config_name_for_path, ce->name);
		if (name_for_path)
			name = name_for_path->util;

		default_argv = "yes";
		if (command_line_option == RECURSE_SUBMODULES_DEFAULT) {
			struct string_list_item *fetch_recurse_submodules_option;
			fetch_recurse_submodules_option = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, name);
			if (fetch_recurse_submodules_option) {
				if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_OFF)
					continue;
				if ((intptr_t)fetch_recurse_submodules_option->util == RECURSE_SUBMODULES_ON_DEMAND) {
					if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
						continue;
					default_argv = "on-demand";
				}
			} else {
				if ((config_fetch_recurse_submodules == RECURSE_SUBMODULES_OFF) ||
				    gitmodules_is_unmerged)
					continue;
				if (config_fetch_recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) {
					if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
						continue;
					default_argv = "on-demand";
				}
			}
		} else if (command_line_option == RECURSE_SUBMODULES_ON_DEMAND) {
			if (!unsorted_string_list_lookup(&changed_submodule_paths, ce->name))
				continue;
			default_argv = "on-demand";
		}

		strbuf_addf(&submodule_path, "%s/%s", work_tree, ce->name);
		strbuf_addf(&submodule_git_dir, "%s/.git", submodule_path.buf);
		strbuf_addf(&submodule_prefix, "%s%s/", prefix, ce->name);
		git_dir = read_gitfile(submodule_git_dir.buf);
		if (!git_dir)
			git_dir = submodule_git_dir.buf;
		if (is_directory(git_dir)) {
			if (!quiet)
				printf("Fetching submodule %s%s\n", prefix, ce->name);
			cp.dir = submodule_path.buf;
			argv[default_argc] = default_argv;
			argv[argc] = submodule_prefix.buf;
			if (run_command(&cp))
				result = 1;
		}
		strbuf_release(&submodule_path);
		strbuf_release(&submodule_git_dir);
		strbuf_release(&submodule_prefix);
	}
	free(argv);
out:
	string_list_clear(&changed_submodule_paths, 1);
	return result;
}

unsigned is_submodule_modified(const char *path, int ignore_untracked)
{
	ssize_t len;
	struct child_process cp;
	const char *argv[] = {
		"status",
		"--porcelain",
		NULL,
		NULL,
	};
	struct strbuf buf = STRBUF_INIT;
	unsigned dirty_submodule = 0;
	const char *line, *next_line;
	const char *git_dir;

	strbuf_addf(&buf, "%s/.git", path);
	git_dir = read_gitfile(buf.buf);
	if (!git_dir)
		git_dir = buf.buf;
	if (!is_directory(git_dir)) {
		strbuf_release(&buf);
		/* The submodule is not checked out, so it is not modified */
		return 0;

	}
	strbuf_reset(&buf);

	if (ignore_untracked)
		argv[2] = "-uno";

	memset(&cp, 0, sizeof(cp));
	cp.argv = argv;
	cp.env = local_repo_env;
	cp.git_cmd = 1;
	cp.no_stdin = 1;
	cp.out = -1;
	cp.dir = path;
	if (start_command(&cp))
		die("Could not run git status --porcelain");

	len = strbuf_read(&buf, cp.out, 1024);
	line = buf.buf;
	while (len > 2) {
		if ((line[0] == '?') && (line[1] == '?')) {
			dirty_submodule |= DIRTY_SUBMODULE_UNTRACKED;
			if (dirty_submodule & DIRTY_SUBMODULE_MODIFIED)
				break;
		} else {
			dirty_submodule |= DIRTY_SUBMODULE_MODIFIED;
			if (ignore_untracked ||
			    (dirty_submodule & DIRTY_SUBMODULE_UNTRACKED))
				break;
		}
		next_line = strchr(line, '\n');
		if (!next_line)
			break;
		next_line++;
		len -= (next_line - line);
		line = next_line;
	}
	close(cp.out);

	if (finish_command(&cp))
		die("git status --porcelain failed");

	strbuf_release(&buf);
	return dirty_submodule;
}

static int find_first_merges(struct object_array *result, const char *path,
		struct commit *a, struct commit *b)
{
	int i, j;
	struct object_array merges;
	struct commit *commit;
	int contains_another;

	char merged_revision[42];
	const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
				   "--all", merged_revision, NULL };
	struct rev_info revs;
	struct setup_revision_opt rev_opts;

	memset(&merges, 0, sizeof(merges));
	memset(result, 0, sizeof(struct object_array));
	memset(&rev_opts, 0, sizeof(rev_opts));

	/* get all revisions that merge commit a */
	snprintf(merged_revision, sizeof(merged_revision), "^%s",
			sha1_to_hex(a->object.sha1));
	init_revisions(&revs, NULL);
	rev_opts.submodule = path;
	setup_revisions(sizeof(rev_args)/sizeof(char *)-1, rev_args, &revs, &rev_opts);

	/* save all revisions from the above list that contain b */
	if (prepare_revision_walk(&revs))
		die("revision walk setup failed");
	while ((commit = get_revision(&revs)) != NULL) {
		struct object *o = &(commit->object);
		if (in_merge_bases(b, &commit, 1))
			add_object_array(o, NULL, &merges);
	}

	/* Now we've got all merges that contain a and b. Prune all
	 * merges that contain another found merge and save them in
	 * result.
	 */
	for (i = 0; i < merges.nr; i++) {
		struct commit *m1 = (struct commit *) merges.objects[i].item;

		contains_another = 0;
		for (j = 0; j < merges.nr; j++) {
			struct commit *m2 = (struct commit *) merges.objects[j].item;
			if (i != j && in_merge_bases(m2, &m1, 1)) {
				contains_another = 1;
				break;
			}
		}

		if (!contains_another)
			add_object_array(merges.objects[i].item,
					 merges.objects[i].name, result);
	}

	free(merges.objects);
	return result->nr;
}

static void print_commit(struct commit *commit)
{
	struct strbuf sb = STRBUF_INIT;
	struct pretty_print_context ctx = {0};
	ctx.date_mode = DATE_NORMAL;
	format_commit_message(commit, " %h: %m %s", &sb, &ctx);
	fprintf(stderr, "%s\n", sb.buf);
	strbuf_release(&sb);
}

#define MERGE_WARNING(path, msg) \
	warning("Failed to merge submodule %s (%s)", path, msg);

int merge_submodule(unsigned char result[20], const char *path,
		    const unsigned char base[20], const unsigned char a[20],
		    const unsigned char b[20])
{
	struct commit *commit_base, *commit_a, *commit_b;
	int parent_count;
	struct object_array merges;

	int i;

	/* store a in result in case we fail */
	hashcpy(result, a);

	/* we can not handle deletion conflicts */
	if (is_null_sha1(base))
		return 0;
	if (is_null_sha1(a))
		return 0;
	if (is_null_sha1(b))
		return 0;

	if (add_submodule_odb(path)) {
		MERGE_WARNING(path, "not checked out");
		return 0;
	}

	if (!(commit_base = lookup_commit_reference(base)) ||
	    !(commit_a = lookup_commit_reference(a)) ||
	    !(commit_b = lookup_commit_reference(b))) {
		MERGE_WARNING(path, "commits not present");
		return 0;
	}

	/* check whether both changes are forward */
	if (!in_merge_bases(commit_base, &commit_a, 1) ||
	    !in_merge_bases(commit_base, &commit_b, 1)) {
		MERGE_WARNING(path, "commits don't follow merge-base");
		return 0;
	}

	/* Case #1: a is contained in b or vice versa */
	if (in_merge_bases(commit_a, &commit_b, 1)) {
		hashcpy(result, b);
		return 1;
	}
	if (in_merge_bases(commit_b, &commit_a, 1)) {
		hashcpy(result, a);
		return 1;
	}

	/*
	 * Case #2: There are one or more merges that contain a and b in
	 * the submodule. If there is only one, then present it as a
	 * suggestion to the user, but leave it marked unmerged so the
	 * user needs to confirm the resolution.
	 */

	/* find commit which merges them */
	parent_count = find_first_merges(&merges, path, commit_a, commit_b);
	switch (parent_count) {
	case 0:
		MERGE_WARNING(path, "merge following commits not found");
		break;

	case 1:
		MERGE_WARNING(path, "not fast-forward");
		fprintf(stderr, "Found a possible merge resolution "
				"for the submodule:\n");
		print_commit((struct commit *) merges.objects[0].item);
		fprintf(stderr,
			"If this is correct simply add it to the index "
			"for example\n"
			"by using:\n\n"
			"  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
			"which will accept this suggestion.\n",
			sha1_to_hex(merges.objects[0].item->sha1), path);
		break;

	default:
		MERGE_WARNING(path, "multiple merges found");
		for (i = 0; i < merges.nr; i++)
			print_commit((struct commit *) merges.objects[i].item);
	}

	free(merges.objects);
	return 0;
}