git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / Atom feed
ece17315d671cf182f21c261d879c58f193cde09 blob 37643 bytes (raw)

   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
 
#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"

static int config_fetch_recurse_submodules = RECURSE_SUBMODULES_ON_DEMAND;
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);
	}
}

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);
}

/* 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;
}

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;
}

int ok_to_remove_submodule(const char *path)
{
	ssize_t len;
	struct child_process cp = CHILD_PROCESS_INIT;
	const char *argv[] = {
		"status",
		"--porcelain",
		"-u",
		"--ignore-submodules=none",
		NULL,
	};
	struct strbuf buf = STRBUF_INIT;
	int ok_to_remove = 1;

	if (!file_exists(path) || is_empty_dir(path))
		return 1;

	if (!submodule_uses_gitfile(path))
		return 0;

	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 -uall --ignore-submodules=none' in submodule %s", path);

	len = strbuf_read(&buf, cp.out, 1024);
	if (len > 2)
		ok_to_remove = 0;
	close(cp.out);

	if (finish_command(&cp))
		die("'git status --porcelain -uall --ignore-submodules=none' failed in submodule %s", path);

	strbuf_release(&buf);
	return ok_to_remove;
}

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;
}

/* Update gitfile and core.worktree setting to connect work tree and git dir */
void connect_work_tree_and_git_dir(const char *work_tree, const char *git_dir)
{
	struct strbuf file_name = STRBUF_INIT;
	struct strbuf rel_path = STRBUF_INIT;
	const char *real_work_tree = xstrdup(real_path(work_tree));

	/* Update gitfile */
	strbuf_addf(&file_name, "%s/.git", work_tree);
	write_file(file_name.buf, "gitdir: %s",
		   relative_path(git_dir, real_work_tree, &rel_path));

	/* Update core.worktree setting */
	strbuf_reset(&file_name);
	strbuf_addf(&file_name, "%s/config", git_dir);
	git_config_set_in_file(file_name.buf, "core.worktree",
			       relative_path(real_work_tree, git_dir,
					     &rel_path));

	strbuf_release(&file_name);
	strbuf_release(&rel_path);
	free((void *)real_work_tree);
}

int parallel_submodules(void)
{
	return parallel_jobs;
}

void prepare_submodule_repo_env(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);
	}
	argv_array_push(out, "GIT_DIR=.git");
}
debug log:

solving ece17315d ...
found ece17315d in https://80x24.org/mirrors/git.git

git@vger.kernel.org list mirror (unofficial, one of many)

Archives are clonable:
	git clone --mirror https://public-inbox.org/git
	git clone --mirror http://ou63pmih66umazou.onion/git
	git clone --mirror http://czquwvybam4bgbro.onion/git
	git clone --mirror http://hjrcffqmbrq6wope.onion/git

Newsgroups are available over NNTP:
	nntp://news.public-inbox.org/inbox.comp.version-control.git
	nntp://ou63pmih66umazou.onion/inbox.comp.version-control.git
	nntp://czquwvybam4bgbro.onion/inbox.comp.version-control.git
	nntp://hjrcffqmbrq6wope.onion/inbox.comp.version-control.git
	nntp://news.gmane.org/gmane.comp.version-control.git

 note: .onion URLs require Tor: https://www.torproject.org/

AGPL code for this site: git clone https://public-inbox.org/ public-inbox