summaryrefslogtreecommitdiff
path: root/submodule.c
blob: d8efbdb96e7dce08233458f44f26b7dae1bc1b34 (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
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
#include "cache.h"
#include "submodule-config.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"
#include "blob.h"
#include "thread-utils.h"
#include "quote.h"
#include "worktree.h"

static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
static int config_update_recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
static int parallel_jobs = 1;
static struct string_list changed_submodule_paths = STRING_LIST_INIT_NODUP;
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;

/*
 * This flag is set if the .gitmodules file had unstaged modifications on
 * startup. This must be checked before allowing modifications to the
 * .gitmodules file with the intention to stage them later, because when
 * continuing we would stage the modifications the user didn't stage herself
 * too. That might change in a future version when we learn to stage the
 * changes we do ourselves without staging any previous modifications.
 */
static int gitmodules_is_modified;

int is_staging_gitmodules_ok(void)
{
	return !gitmodules_is_modified;
}

/*
 * Try to update the "path" entry in the "submodule.<name>" section of the
 * .gitmodules file. Return 0 only if a .gitmodules file was found, a section
 * with the correct path=<oldpath> setting was found and we could update it.
 */
int update_path_in_gitmodules(const char *oldpath, const char *newpath)
{
	struct strbuf entry = STRBUF_INIT;
	const struct submodule *submodule;

	if (!file_exists(".gitmodules")) /* Do nothing without .gitmodules */
		return -1;

	if (gitmodules_is_unmerged)
		die(_("Cannot change unmerged .gitmodules, resolve merge conflicts first"));

	submodule = submodule_from_path(null_sha1, oldpath);
	if (!submodule || !submodule->name) {
		warning(_("Could not find section in .gitmodules where path=%s"), oldpath);
		return -1;
	}
	strbuf_addstr(&entry, "submodule.");
	strbuf_addstr(&entry, submodule->name);
	strbuf_addstr(&entry, ".path");
	if (git_config_set_in_file_gently(".gitmodules", entry.buf, newpath) < 0) {
		/* Maybe the user already did that, don't error out here */
		warning(_("Could not update .gitmodules entry %s"), entry.buf);
		strbuf_release(&entry);
		return -1;
	}
	strbuf_release(&entry);
	return 0;
}

/*
 * Try to remove the "submodule.<name>" section from .gitmodules where the given
 * path is configured. Return 0 only if a .gitmodules file was found, a section
 * with the correct path=<path> setting was found and we could remove it.
 */
int remove_path_from_gitmodules(const char *path)
{
	struct strbuf sect = STRBUF_INIT;
	const struct submodule *submodule;

	if (!file_exists(".gitmodules")) /* Do nothing without .gitmodules */
		return -1;

	if (gitmodules_is_unmerged)
		die(_("Cannot change unmerged .gitmodules, resolve merge conflicts first"));

	submodule = submodule_from_path(null_sha1, path);
	if (!submodule || !submodule->name) {
		warning(_("Could not find section in .gitmodules where path=%s"), path);
		return -1;
	}
	strbuf_addstr(&sect, "submodule.");
	strbuf_addstr(&sect, submodule->name);
	if (git_config_rename_section_in_file(".gitmodules", sect.buf, NULL) < 0) {
		/* Maybe the user already did that, don't error out here */
		warning(_("Could not remove .gitmodules entry for %s"), path);
		strbuf_release(&sect);
		return -1;
	}
	strbuf_release(&sect);
	return 0;
}

void stage_updated_gitmodules(void)
{
	if (add_file_to_cache(".gitmodules", 0))
		die(_("staging updated .gitmodules failed"));
}

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

	ret = strbuf_git_path_submodule(&objects_directory, path, "objects/");
	if (ret)
		goto done;
	if (!is_directory(objects_directory.buf)) {
		ret = -1;
		goto done;
	}
	add_to_alternates_memory(objects_directory.buf);
done:
	strbuf_release(&objects_directory);
	return ret;
}

void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt,
					     const char *path)
{
	const struct submodule *submodule = submodule_from_path(null_sha1, path);
	if (submodule) {
		if (submodule->ignore)
			handle_ignore_submodules_arg(diffopt, submodule->ignore);
		else if (gitmodules_is_unmerged)
			DIFF_OPT_SET(diffopt, IGNORE_SUBMODULES);
	}
}

int submodule_config(const char *var, const char *value, void *cb)
{
	if (!strcmp(var, "submodule.fetchjobs")) {
		parallel_jobs = git_config_int(var, value);
		if (parallel_jobs < 0)
			die(_("negative values not allowed for submodule.fetchJobs"));
		return 0;
	} else if (starts_with(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;
			}
		} else if (pos < active_nr) {
			struct stat st;
			if (lstat(".gitmodules", &st) == 0 &&
			    ce_match_stat(active_cache[pos], &st, 0) & DATA_CHANGED)
				gitmodules_is_modified = 1;
		}

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

void gitmodules_config_sha1(const unsigned char *commit_sha1)
{
	struct strbuf rev = STRBUF_INIT;
	unsigned char sha1[20];

	if (gitmodule_sha1_from_commit(commit_sha1, sha1, &rev)) {
		git_config_from_blob_sha1(submodule_config, rev.buf,
					  sha1, NULL);
	}
	strbuf_release(&rev);
}

/*
 * Determine if a submodule has been initialized at a given 'path'
 */
int is_submodule_initialized(const char *path)
{
	int ret = 0;
	const struct submodule *module = NULL;

	module = submodule_from_path(null_sha1, path);

	if (module) {
		char *key = xstrfmt("submodule.%s.url", module->name);
		char *value = NULL;

		ret = !git_config_get_string(key, &value);

		free(value);
		free(key);
	}

	return ret;
}

int is_submodule_populated_gently(const char *path, int *return_error_code)
{
	int ret = 0;
	char *gitdir = xstrfmt("%s/.git", path);

	if (resolve_gitdir_gently(gitdir, return_error_code))
		ret = 1;

	free(gitdir);
	return ret;
}

int parse_submodule_update_strategy(const char *value,
		struct submodule_update_strategy *dst)
{
	free((void*)dst->command);
	dst->command = NULL;
	if (!strcmp(value, "none"))
		dst->type = SM_UPDATE_NONE;
	else if (!strcmp(value, "checkout"))
		dst->type = SM_UPDATE_CHECKOUT;
	else if (!strcmp(value, "rebase"))
		dst->type = SM_UPDATE_REBASE;
	else if (!strcmp(value, "merge"))
		dst->type = SM_UPDATE_MERGE;
	else if (skip_prefix(value, "!", &value)) {
		dst->type = SM_UPDATE_COMMAND;
		dst->command = xstrdup(value);
	} else
		return -1;
	return 0;
}

const char *submodule_strategy_to_string(const struct submodule_update_strategy *s)
{
	struct strbuf sb = STRBUF_INIT;
	switch (s->type) {
	case SM_UPDATE_CHECKOUT:
		return "checkout";
	case SM_UPDATE_MERGE:
		return "merge";
	case SM_UPDATE_REBASE:
		return "rebase";
	case SM_UPDATE_NONE:
		return "none";
	case SM_UPDATE_UNSPECIFIED:
		return NULL;
	case SM_UPDATE_COMMAND:
		strbuf_addf(&sb, "!%s", s->command);
		return strbuf_detach(&sb, NULL);
	}
	return NULL;
}

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,
		struct commit_list *merge_bases)
{
	struct commit_list *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);
	for (list = merge_bases; list; list = list->next) {
		list->item->object.flags |= UNINTERESTING;
		add_pending_object(rev, &list->item->object,
			oid_to_hex(&list->item->object.oid));
	}
	return prepare_revision_walk(rev);
}

static void print_submodule_summary(struct rev_info *rev, FILE *f,
		const char *line_prefix,
		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;
		ctx.output_encoding = get_log_output_encoding();
		strbuf_setlen(&sb, 0);
		strbuf_addstr(&sb, line_prefix);
		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);
}

static void prepare_submodule_repo_env_no_git_dir(struct argv_array *out)
{
	const char * const *var;

	for (var = local_repo_env; *var; var++) {
		if (strcmp(*var, CONFIG_DATA_ENVIRONMENT))
			argv_array_push(out, *var);
	}
}

void prepare_submodule_repo_env(struct argv_array *out)
{
	prepare_submodule_repo_env_no_git_dir(out);
	argv_array_pushf(out, "%s=%s", GIT_DIR_ENVIRONMENT,
			 DEFAULT_GIT_DIR_ENVIRONMENT);
}

/* Helper function to display the submodule header line prior to the full
 * summary output. If it can locate the submodule objects directory it will
 * attempt to lookup both the left and right commits and put them into the
 * left and right pointers.
 */
static void show_submodule_header(FILE *f, const char *path,
		const char *line_prefix,
		struct object_id *one, struct object_id *two,
		unsigned dirty_submodule, const char *meta,
		const char *reset,
		struct commit **left, struct commit **right,
		struct commit_list **merge_bases)
{
	const char *message = NULL;
	struct strbuf sb = STRBUF_INIT;
	int fast_forward = 0, fast_backward = 0;

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

	if (is_null_oid(one))
		message = "(new submodule)";
	else if (is_null_oid(two))
		message = "(submodule deleted)";

	if (add_submodule_odb(path)) {
		if (!message)
			message = "(not initialized)";
		goto output_header;
	}

	/*
	 * Attempt to lookup the commit references, and determine if this is
	 * a fast forward or fast backwards update.
	 */
	*left = lookup_commit_reference(one->hash);
	*right = lookup_commit_reference(two->hash);

	/*
	 * Warn about missing commits in the submodule project, but only if
	 * they aren't null.
	 */
	if ((!is_null_oid(one) && !*left) ||
	     (!is_null_oid(two) && !*right))
		message = "(commits not present)";

	*merge_bases = get_merge_bases(*left, *right);
	if (*merge_bases) {
		if ((*merge_bases)->item == *left)
			fast_forward = 1;
		else if ((*merge_bases)->item == *right)
			fast_backward = 1;
	}

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

output_header:
	strbuf_addf(&sb, "%s%sSubmodule %s ", line_prefix, meta, path);
	strbuf_add_unique_abbrev(&sb, one->hash, DEFAULT_ABBREV);
	strbuf_addstr(&sb, (fast_backward || fast_forward) ? ".." : "...");
	strbuf_add_unique_abbrev(&sb, two->hash, DEFAULT_ABBREV);
	if (message)
		strbuf_addf(&sb, " %s%s\n", message, reset);
	else
		strbuf_addf(&sb, "%s:%s\n", fast_backward ? " (rewind)" : "", reset);
	fwrite(sb.buf, sb.len, 1, f);

	strbuf_release(&sb);
}

void show_submodule_summary(FILE *f, const char *path,
		const char *line_prefix,
		struct object_id *one, struct object_id *two,
		unsigned dirty_submodule, const char *meta,
		const char *del, const char *add, const char *reset)
{
	struct rev_info rev;
	struct commit *left = NULL, *right = NULL;
	struct commit_list *merge_bases = NULL;

	show_submodule_header(f, path, line_prefix, one, two, dirty_submodule,
			      meta, reset, &left, &right, &merge_bases);

	/*
	 * If we don't have both a left and a right pointer, there is no
	 * reason to try and display a summary. The header line should contain
	 * all the information the user needs.
	 */
	if (!left || !right)
		goto out;

	/* Treat revision walker failure the same as missing commits */
	if (prepare_submodule_summary(&rev, path, left, right, merge_bases)) {
		fprintf(f, "%s(revision walker failed)\n", line_prefix);
		goto out;
	}

	print_submodule_summary(&rev, f, line_prefix, del, add, reset);

out:
	if (merge_bases)
		free_commit_list(merge_bases);
	clear_commit_marks(left, ~0);
	clear_commit_marks(right, ~0);
}

void show_submodule_inline_diff(FILE *f, const char *path,
		const char *line_prefix,
		struct object_id *one, struct object_id *two,
		unsigned dirty_submodule, const char *meta,
		const char *del, const char *add, const char *reset,
		const struct diff_options *o)
{
	const struct object_id *old = &empty_tree_oid, *new = &empty_tree_oid;
	struct commit *left = NULL, *right = NULL;
	struct commit_list *merge_bases = NULL;
	struct strbuf submodule_dir = STRBUF_INIT;
	struct child_process cp = CHILD_PROCESS_INIT;

	show_submodule_header(f, path, line_prefix, one, two, dirty_submodule,
			      meta, reset, &left, &right, &merge_bases);

	/* We need a valid left and right commit to display a difference */
	if (!(left || is_null_oid(one)) ||
	    !(right || is_null_oid(two)))
		goto done;

	if (left)
		old = one;
	if (right)
		new = two;

	fflush(f);
	cp.git_cmd = 1;
	cp.dir = path;
	cp.out = dup(fileno(f));
	cp.no_stdin = 1;

	/* TODO: other options may need to be passed here. */
	argv_array_push(&cp.args, "diff");
	argv_array_pushf(&cp.args, "--line-prefix=%s", line_prefix);
	if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
		argv_array_pushf(&cp.args, "--src-prefix=%s%s/",
				 o->b_prefix, path);
		argv_array_pushf(&cp.args, "--dst-prefix=%s%s/",
				 o->a_prefix, path);
	} else {
		argv_array_pushf(&cp.args, "--src-prefix=%s%s/",
				 o->a_prefix, path);
		argv_array_pushf(&cp.args, "--dst-prefix=%s%s/",
				 o->b_prefix, path);
	}
	argv_array_push(&cp.args, oid_to_hex(old));
	/*
	 * If the submodule has modified content, we will diff against the
	 * work tree, under the assumption that the user has asked for the
	 * diff format and wishes to actually see all differences even if they
	 * haven't yet been committed to the submodule yet.
	 */
	if (!(dirty_submodule & DIRTY_SUBMODULE_MODIFIED))
		argv_array_push(&cp.args, oid_to_hex(new));

	if (run_command(&cp))
		fprintf(f, "(diff failed)\n");

done:
	strbuf_release(&submodule_dir);
	if (merge_bases)
		free_commit_list(merge_bases);
	if (left)
		clear_commit_marks(left, ~0);
	if (right)
		clear_commit_marks(right, ~0);
}

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

void set_config_update_recurse_submodules(int value)
{
	config_update_recurse_submodules = value;
}

int should_update_submodules(void)
{
	return config_update_recurse_submodules == RECURSE_SUBMODULES_ON;
}

const struct submodule *submodule_from_ce(const struct cache_entry *ce)
{
	if (!S_ISGITLINK(ce->ce_mode))
		return NULL;

	if (!should_update_submodules())
		return NULL;

	return submodule_from_path(null_sha1, ce->name);
}

static int has_remote(const char *refname, const struct object_id *oid,
		      int flags, void *cb_data)
{
	return 1;
}

static int append_sha1_to_argv(const unsigned char sha1[20], void *data)
{
	struct argv_array *argv = data;
	argv_array_push(argv, sha1_to_hex(sha1));
	return 0;
}

static int check_has_commit(const unsigned char sha1[20], void *data)
{
	int *has_commit = data;

	if (!lookup_commit_reference(sha1))
		*has_commit = 0;

	return 0;
}

static int submodule_has_commits(const char *path, struct sha1_array *commits)
{
	int has_commit = 1;

	if (add_submodule_odb(path))
		return 0;

	sha1_array_for_each_unique(commits, check_has_commit, &has_commit);
	return has_commit;
}

static int submodule_needs_pushing(const char *path, struct sha1_array *commits)
{
	if (!submodule_has_commits(path, commits))
		/*
		 * NOTE: We do consider it safe to return "no" here. The
		 * correct answer would be "We do not know" instead of
		 * "No push needed", but it is quite hard to change
		 * the submodule pointer without having the submodule
		 * around. If a user did however change the submodules
		 * without having the submodule around, this indicates
		 * an expert who knows what they are doing or a
		 * maintainer integrating work from other people. In
		 * both cases it should be safe to skip this check.
		 */
		return 0;

	if (for_each_remote_ref_submodule(path, has_remote, NULL) > 0) {
		struct child_process cp = CHILD_PROCESS_INIT;
		struct strbuf buf = STRBUF_INIT;
		int needs_pushing = 0;

		argv_array_push(&cp.args, "rev-list");
		sha1_array_for_each_unique(commits, append_sha1_to_argv, &cp.args);
		argv_array_pushl(&cp.args, "--not", "--remotes", "-n", "1" , NULL);

		prepare_submodule_repo_env(&cp.env_array);
		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 <commits> --not --remotes -n 1' command in submodule %s",
					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 struct sha1_array *submodule_commits(struct string_list *submodules,
					    const char *path)
{
	struct string_list_item *item;

	item = string_list_insert(submodules, path);
	if (item->util)
		return (struct sha1_array *) item->util;

	/* NEEDSWORK: should we have sha1_array_init()? */
	item->util = xcalloc(1, sizeof(struct sha1_array));
	return (struct sha1_array *) item->util;
}

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

	for (i = 0; i < q->nr; i++) {
		struct diff_filepair *p = q->queue[i];
		struct sha1_array *commits;
		if (!S_ISGITLINK(p->two->mode))
			continue;
		commits = submodule_commits(submodules, p->two->path);
		sha1_array_append(commits, p->two->oid.hash);
	}
}

static void find_unpushed_submodule_commits(struct commit *commit,
		struct string_list *needs_pushing)
{
	struct rev_info rev;

	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_merge(commit, 1, &rev);
}

static void free_submodules_sha1s(struct string_list *submodules)
{
	struct string_list_item *item;
	for_each_string_list_item(item, submodules)
		sha1_array_clear((struct sha1_array *) item->util);
	string_list_clear(submodules, 1);
}

int find_unpushed_submodules(struct sha1_array *commits,
		const char *remotes_name, struct string_list *needs_pushing)
{
	struct rev_info rev;
	struct commit *commit;
	struct string_list submodules = STRING_LIST_INIT_DUP;
	struct string_list_item *submodule;
	struct argv_array argv = ARGV_ARRAY_INIT;

	init_revisions(&rev, NULL);

	/* argv.argv[0] will be ignored by setup_revisions */
	argv_array_push(&argv, "find_unpushed_submodules");
	sha1_array_for_each_unique(commits, append_sha1_to_argv, &argv);
	argv_array_push(&argv, "--not");
	argv_array_pushf(&argv, "--remotes=%s", remotes_name);

	setup_revisions(argv.argc, argv.argv, &rev, NULL);
	if (prepare_revision_walk(&rev))
		die("revision walk setup failed");

	while ((commit = get_revision(&rev)) != NULL)
		find_unpushed_submodule_commits(commit, &submodules);

	reset_revision_walk();
	argv_array_clear(&argv);

	for_each_string_list_item(submodule, &submodules) {
		struct sha1_array *commits = (struct sha1_array *) submodule->util;

		if (submodule_needs_pushing(submodule->string, commits))
			string_list_insert(needs_pushing, submodule->string);
	}
	free_submodules_sha1s(&submodules);

	return needs_pushing->nr;
}

static int push_submodule(const char *path, int dry_run)
{
	if (add_submodule_odb(path))
		return 1;

	if (for_each_remote_ref_submodule(path, has_remote, NULL) > 0) {
		struct child_process cp = CHILD_PROCESS_INIT;
		argv_array_push(&cp.args, "push");
		if (dry_run)
			argv_array_push(&cp.args, "--dry-run");

		prepare_submodule_repo_env(&cp.env_array);
		cp.git_cmd = 1;
		cp.no_stdin = 1;
		cp.dir = path;
		if (run_command(&cp))
			return 0;
		close(cp.out);
	}

	return 1;
}

int push_unpushed_submodules(struct sha1_array *commits,
			     const char *remotes_name,
			     int dry_run)
{
	int i, ret = 1;
	struct string_list needs_pushing = STRING_LIST_INIT_DUP;

	if (!find_unpushed_submodules(commits, remotes_name, &needs_pushing))
		return 1;

	for (i = 0; i < needs_pushing.nr; i++) {
		const char *path = needs_pushing.items[i].string;
		fprintf(stderr, "Pushing submodule '%s'\n", path);
		if (!push_submodule(path, dry_run)) {
			fprintf(stderr, "Unable to push submodule '%s'\n", path);
			ret = 0;
		}
	}

	string_list_clear(&needs_pushing, 0);

	return ret;
}

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 = CHILD_PROCESS_INIT;
		const char *argv[] = {"rev-list", "-n", "1", NULL, "--not", "--all", NULL};
		struct strbuf buf = STRBUF_INIT;

		argv[3] = sha1_to_hex(sha1);
		cp.argv = argv;
		prepare_submodule_repo_env(&cp.env_array);
		cp.git_cmd = 1;
		cp.no_stdin = 1;
		cp.dir = path;
		if (!capture_command(&cp, &buf, 1024) && !buf.len)
			is_present = 1;

		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->oid.hash))
				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 struct object_id *oid,
			     int flags, void *data)
{
	sha1_array_append(data, oid->hash);
	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 int add_sha1_to_argv(const unsigned char sha1[20], void *data)
{
	argv_array_push(data, sha1_to_hex(sha1));
	return 0;
}

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 (!submodule_from_path(NULL, NULL))
		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;
			diff_setup_done(&diff_opts);
			diff_tree_sha1(parent->item->object.oid.hash, commit->object.oid.hash, "", &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;
}

struct submodule_parallel_fetch {
	int count;
	struct argv_array args;
	const char *work_tree;
	const char *prefix;
	int command_line_option;
	int quiet;
	int result;
};
#define SPF_INIT {0, ARGV_ARRAY_INIT, NULL, NULL, 0, 0, 0}

static int get_next_submodule(struct child_process *cp,
			      struct strbuf *err, void *data, void **task_cb)
{
	int ret = 0;
	struct submodule_parallel_fetch *spf = data;

	for (; spf->count < active_nr; spf->count++) {
		struct strbuf submodule_path = STRBUF_INIT;
		struct strbuf submodule_git_dir = STRBUF_INIT;
		struct strbuf submodule_prefix = STRBUF_INIT;
		const struct cache_entry *ce = active_cache[spf->count];
		const char *git_dir, *default_argv;
		const struct submodule *submodule;

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

		submodule = submodule_from_path(null_sha1, ce->name);
		if (!submodule)
			submodule = submodule_from_name(null_sha1, ce->name);

		default_argv = "yes";
		if (spf->command_line_option == RECURSE_SUBMODULES_DEFAULT) {
			if (submodule &&
			    submodule->fetch_recurse !=
						RECURSE_SUBMODULES_NONE) {
				if (submodule->fetch_recurse ==
						RECURSE_SUBMODULES_OFF)
					continue;
				if (submodule->fetch_recurse ==
						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 (spf->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", spf->work_tree, ce->name);
		strbuf_addf(&submodule_git_dir, "%s/.git", submodule_path.buf);
		strbuf_addf(&submodule_prefix, "%s%s/", spf->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)) {
			child_process_init(cp);
			cp->dir = strbuf_detach(&submodule_path, NULL);
			prepare_submodule_repo_env(&cp->env_array);
			cp->git_cmd = 1;
			if (!spf->quiet)
				strbuf_addf(err, "Fetching submodule %s%s\n",
					    spf->prefix, ce->name);
			argv_array_init(&cp->args);
			argv_array_pushv(&cp->args, spf->args.argv);
			argv_array_push(&cp->args, default_argv);
			argv_array_push(&cp->args, "--submodule-prefix");
			argv_array_push(&cp->args, submodule_prefix.buf);
			ret = 1;
		}
		strbuf_release(&submodule_path);
		strbuf_release(&submodule_git_dir);
		strbuf_release(&submodule_prefix);
		if (ret) {
			spf->count++;
			return 1;
		}
	}
	return 0;
}

static int fetch_start_failure(struct strbuf *err,
			       void *cb, void *task_cb)
{
	struct submodule_parallel_fetch *spf = cb;

	spf->result = 1;

	return 0;
}

static int fetch_finish(int retvalue, struct strbuf *err,
			void *cb, void *task_cb)
{
	struct submodule_parallel_fetch *spf = cb;

	if (retvalue)
		spf->result = 1;

	return 0;
}

int fetch_populated_submodules(const struct argv_array *options,
			       const char *prefix, int command_line_option,
			       int quiet, int max_parallel_jobs)
{
	int i;
	struct submodule_parallel_fetch spf = SPF_INIT;

	spf.work_tree = get_git_work_tree();
	spf.command_line_option = command_line_option;
	spf.quiet = quiet;
	spf.prefix = prefix;

	if (!spf.work_tree)
		goto out;

	if (read_cache() < 0)
		die("index file corrupt");

	argv_array_push(&spf.args, "fetch");
	for (i = 0; i < options->argc; i++)
		argv_array_push(&spf.args, options->argv[i]);
	argv_array_push(&spf.args, "--recurse-submodules-default");
	/* default value, "--submodule-prefix" and its value are added later */

	if (max_parallel_jobs < 0)
		max_parallel_jobs = parallel_jobs;

	calculate_changed_submodule_paths();
	run_processes_parallel(max_parallel_jobs,
			       get_next_submodule,
			       fetch_start_failure,
			       fetch_finish,
			       &spf);

	argv_array_clear(&spf.args);
out:
	string_list_clear(&changed_submodule_paths, 1);
	return spf.result;
}

unsigned is_submodule_modified(const char *path, int ignore_untracked)
{
	ssize_t len;
	struct child_process cp = CHILD_PROCESS_INIT;
	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";

	cp.argv = argv;
	prepare_submodule_repo_env(&cp.env_array);
	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' in submodule %s", path);

	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 in submodule %s", path);

	strbuf_release(&buf);
	return dirty_submodule;
}

int submodule_uses_gitfile(const char *path)
{
	struct child_process cp = CHILD_PROCESS_INIT;
	const char *argv[] = {
		"submodule",
		"foreach",
		"--quiet",
		"--recursive",
		"test -f .git",
		NULL,
	};
	struct strbuf buf = STRBUF_INIT;
	const char *git_dir;

	strbuf_addf(&buf, "%s/.git", path);
	git_dir = read_gitfile(buf.buf);
	if (!git_dir) {
		strbuf_release(&buf);
		return 0;
	}
	strbuf_release(&buf);

	/* Now test that all nested submodules use a gitfile too */
	cp.argv = argv;
	prepare_submodule_repo_env(&cp.env_array);
	cp.git_cmd = 1;
	cp.no_stdin = 1;
	cp.no_stderr = 1;
	cp.no_stdout = 1;
	cp.dir = path;
	if (run_command(&cp))
		return 0;

	return 1;
}

/*
 * Check if it is a bad idea to remove a submodule, i.e. if we'd lose data
 * when doing so.
 *
 * Return 1 if we'd lose data, return 0 if the removal is fine,
 * and negative values for errors.
 */
int bad_to_remove_submodule(const char *path, unsigned flags)
{
	ssize_t len;
	struct child_process cp = CHILD_PROCESS_INIT;
	struct strbuf buf = STRBUF_INIT;
	int ret = 0;

	if (!file_exists(path) || is_empty_dir(path))
		return 0;

	if (!submodule_uses_gitfile(path))
		return 1;

	argv_array_pushl(&cp.args, "status", "--porcelain",
				   "--ignore-submodules=none", NULL);

	if (flags & SUBMODULE_REMOVAL_IGNORE_UNTRACKED)
		argv_array_push(&cp.args, "-uno");
	else
		argv_array_push(&cp.args, "-uall");

	if (!(flags & SUBMODULE_REMOVAL_IGNORE_IGNORED_UNTRACKED))
		argv_array_push(&cp.args, "--ignored");

	prepare_submodule_repo_env(&cp.env_array);
	cp.git_cmd = 1;
	cp.no_stdin = 1;
	cp.out = -1;
	cp.dir = path;
	if (start_command(&cp)) {
		if (flags & SUBMODULE_REMOVAL_DIE_ON_ERROR)
			die(_("could not start 'git status in submodule '%s'"),
				path);
		ret = -1;
		goto out;
	}

	len = strbuf_read(&buf, cp.out, 1024);
	if (len > 2)
		ret = 1;
	close(cp.out);

	if (finish_command(&cp)) {
		if (flags & SUBMODULE_REMOVAL_DIE_ON_ERROR)
			die(_("could not run 'git status in submodule '%s'"),
				path);
		ret = -1;
	}
out:
	strbuf_release(&buf);
	return ret;
}

static const char *get_super_prefix_or_empty(void)
{
	const char *s = get_super_prefix();
	if (!s)
		s = "";
	return s;
}

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 = OBJECT_ARRAY_INIT;
	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(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",
			oid_to_hex(&a->object.oid));
	init_revisions(&revs, NULL);
	rev_opts.submodule = path;
	setup_revisions(ARRAY_SIZE(rev_args)-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))
			add_object_array(o, NULL, &merges);
	}
	reset_revision_walk();

	/* 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)) {
				contains_another = 1;
				break;
			}
		}

		if (!contains_another)
			add_object_array(merges.objects[i].item, NULL, 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.type = 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], int search)
{
	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) ||
	    !in_merge_bases(commit_base, commit_b)) {
		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)) {
		hashcpy(result, b);
		return 1;
	}
	if (in_merge_bases(commit_b, commit_a)) {
		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.
	 */

	/* Skip the search if makes no sense to the calling context.  */
	if (!search)
		return 0;

	/* 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",
			oid_to_hex(&merges.objects[0].item->oid), 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;
}

int parallel_submodules(void)
{
	return parallel_jobs;
}

/*
 * Embeds a single submodules git directory into the superprojects git dir,
 * non recursively.
 */
static void relocate_single_git_dir_into_superproject(const char *prefix,
						      const char *path)
{
	char *old_git_dir = NULL, *real_old_git_dir = NULL, *real_new_git_dir = NULL;
	const char *new_git_dir;
	const struct submodule *sub;

	if (submodule_uses_worktrees(path))
		die(_("relocate_gitdir for submodule '%s' with "
		      "more than one worktree not supported"), path);

	old_git_dir = xstrfmt("%s/.git", path);
	if (read_gitfile(old_git_dir))
		/* If it is an actual gitfile, it doesn't need migration. */
		return;

	real_old_git_dir = real_pathdup(old_git_dir);

	sub = submodule_from_path(null_sha1, path);
	if (!sub)
		die(_("could not lookup name for submodule '%s'"), path);

	new_git_dir = git_path("modules/%s", sub->name);
	if (safe_create_leading_directories_const(new_git_dir) < 0)
		die(_("could not create directory '%s'"), new_git_dir);
	real_new_git_dir = real_pathdup(new_git_dir);

	fprintf(stderr, _("Migrating git directory of '%s%s' from\n'%s' to\n'%s'\n"),
		get_super_prefix_or_empty(), path,
		real_old_git_dir, real_new_git_dir);

	relocate_gitdir(path, real_old_git_dir, real_new_git_dir);

	free(old_git_dir);
	free(real_old_git_dir);
	free(real_new_git_dir);
}

/*
 * Migrate the git directory of the submodule given by path from
 * having its git directory within the working tree to the git dir nested
 * in its superprojects git dir under modules/.
 */
void absorb_git_dir_into_superproject(const char *prefix,
				      const char *path,
				      unsigned flags)
{
	int err_code;
	const char *sub_git_dir;
	struct strbuf gitdir = STRBUF_INIT;
	strbuf_addf(&gitdir, "%s/.git", path);
	sub_git_dir = resolve_gitdir_gently(gitdir.buf, &err_code);

	/* Not populated? */
	if (!sub_git_dir) {
		const struct submodule *sub;

		if (err_code == READ_GITFILE_ERR_STAT_FAILED) {
			/* unpopulated as expected */
			strbuf_release(&gitdir);
			return;
		}

		if (err_code != READ_GITFILE_ERR_NOT_A_REPO)
			/* We don't know what broke here. */
			read_gitfile_error_die(err_code, path, NULL);

		/*
		* Maybe populated, but no git directory was found?
		* This can happen if the superproject is a submodule
		* itself and was just absorbed. The absorption of the
		* superproject did not rewrite the git file links yet,
		* fix it now.
		*/
		sub = submodule_from_path(null_sha1, path);
		if (!sub)
			die(_("could not lookup name for submodule '%s'"), path);
		connect_work_tree_and_git_dir(path,
			git_path("modules/%s", sub->name));
	} else {
		/* Is it already absorbed into the superprojects git dir? */
		char *real_sub_git_dir = real_pathdup(sub_git_dir);
		char *real_common_git_dir = real_pathdup(get_git_common_dir());

		if (!starts_with(real_sub_git_dir, real_common_git_dir))
			relocate_single_git_dir_into_superproject(prefix, path);

		free(real_sub_git_dir);
		free(real_common_git_dir);
	}
	strbuf_release(&gitdir);

	if (flags & ABSORB_GITDIR_RECURSE_SUBMODULES) {
		struct child_process cp = CHILD_PROCESS_INIT;
		struct strbuf sb = STRBUF_INIT;

		if (flags & ~ABSORB_GITDIR_RECURSE_SUBMODULES)
			die("BUG: we don't know how to pass the flags down?");

		strbuf_addstr(&sb, get_super_prefix_or_empty());
		strbuf_addstr(&sb, path);
		strbuf_addch(&sb, '/');

		cp.dir = path;
		cp.git_cmd = 1;
		cp.no_stdin = 1;
		argv_array_pushl(&cp.args, "--super-prefix", sb.buf,
					   "submodule--helper",
					   "absorb-git-dirs", NULL);
		prepare_submodule_repo_env(&cp.env_array);
		if (run_command(&cp))
			die(_("could not recurse into submodule '%s'"), path);

		strbuf_release(&sb);
	}
}