summaryrefslogtreecommitdiff
path: root/remote.c
blob: 73d33f2584b061085fcaa0958c26b1c3d4665904 (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
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
#include "cache.h"
#include "remote.h"
#include "refs.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "dir.h"
#include "tag.h"
 
static struct refspec s_tag_refspec = {
	0,
	1,
	0,
	"refs/tags/*",
	"refs/tags/*"
};
 
const struct refspec *tag_refspec = &s_tag_refspec;
 
struct counted_string {
	size_t len;
	const char *s;
};
struct rewrite {
	const char *base;
	size_t baselen;
	struct counted_string *instead_of;
	int instead_of_nr;
	int instead_of_alloc;
};
struct rewrites {
	struct rewrite **rewrite;
	int rewrite_alloc;
	int rewrite_nr;
};
 
static struct remote **remotes;
static int remotes_alloc;
static int remotes_nr;
 
static struct branch **branches;
static int branches_alloc;
static int branches_nr;
 
static struct branch *current_branch;
static const char *default_remote_name;
static int explicit_default_remote_name;
 
static struct rewrites rewrites;
static struct rewrites rewrites_push;
 
#define BUF_SIZE (2048)
static char buffer[BUF_SIZE];
 
static const char *alias_url(const char *url, struct rewrites *r)
{
	int i, j;
	char *ret;
	struct counted_string *longest;
	int longest_i;
 
	longest = NULL;
	longest_i = -1;
	for (i = 0; i < r->rewrite_nr; i++) {
		if (!r->rewrite[i])
			continue;
		for (j = 0; j < r->rewrite[i]->instead_of_nr; j++) {
			if (!prefixcmp(url, r->rewrite[i]->instead_of[j].s) &&
			    (!longest ||
			     longest->len < r->rewrite[i]->instead_of[j].len)) {
				longest = &(r->rewrite[i]->instead_of[j]);
				longest_i = i;
			}
		}
	}
	if (!longest)
		return url;
 
	ret = xmalloc(r->rewrite[longest_i]->baselen +
		     (strlen(url) - longest->len) + 1);
	strcpy(ret, r->rewrite[longest_i]->base);
	strcpy(ret + r->rewrite[longest_i]->baselen, url + longest->len);
	return ret;
}
 
static void add_push_refspec(struct remote *remote, const char *ref)
{
	ALLOC_GROW(remote->push_refspec,
		   remote->push_refspec_nr + 1,
		   remote->push_refspec_alloc);
	remote->push_refspec[remote->push_refspec_nr++] = ref;
}
 
static void add_fetch_refspec(struct remote *remote, const char *ref)
{
	ALLOC_GROW(remote->fetch_refspec,
		   remote->fetch_refspec_nr + 1,
		   remote->fetch_refspec_alloc);
	remote->fetch_refspec[remote->fetch_refspec_nr++] = ref;
}
 
static void add_url(struct remote *remote, const char *url)
{
	ALLOC_GROW(remote->url, remote->url_nr + 1, remote->url_alloc);
	remote->url[remote->url_nr++] = url;
}
 
static void add_pushurl(struct remote *remote, const char *pushurl)
{
	ALLOC_GROW(remote->pushurl, remote->pushurl_nr + 1, remote->pushurl_alloc);
	remote->pushurl[remote->pushurl_nr++] = pushurl;
}
 
static void add_pushurl_alias(struct remote *remote, const char *url)
{
	const char *pushurl = alias_url(url, &rewrites_push);
	if (pushurl != url)
		add_pushurl(remote, pushurl);
}
 
static void add_url_alias(struct remote *remote, const char *url)
{
	add_url(remote, alias_url(url, &rewrites));
	add_pushurl_alias(remote, url);
}
 
static struct remote *make_remote(const char *name, int len)
{
	struct remote *ret;
	int i;
 
	for (i = 0; i < remotes_nr; i++) {
		if (len ? (!strncmp(name, remotes[i]->name, len) &&
			   !remotes[i]->name[len]) :
		    !strcmp(name, remotes[i]->name))
			return remotes[i];
	}
 
	ret = xcalloc(1, sizeof(struct remote));
	ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
	remotes[remotes_nr++] = ret;
	if (len)
		ret->name = xstrndup(name, len);
	else
		ret->name = xstrdup(name);
	return ret;
}
 
static void add_merge(struct branch *branch, const char *name)
{
	ALLOC_GROW(branch->merge_name, branch->merge_nr + 1,
		   branch->merge_alloc);
	branch->merge_name[branch->merge_nr++] = name;
}
 
static struct branch *make_branch(const char *name, int len)
{
	struct branch *ret;
	int i;
	char *refname;
 
	for (i = 0; i < branches_nr; i++) {
		if (len ? (!strncmp(name, branches[i]->name, len) &&
			   !branches[i]->name[len]) :
		    !strcmp(name, branches[i]->name))
			return branches[i];
	}
 
	ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
	ret = xcalloc(1, sizeof(struct branch));
	branches[branches_nr++] = ret;
	if (len)
		ret->name = xstrndup(name, len);
	else
		ret->name = xstrdup(name);
	refname = xmalloc(strlen(name) + strlen("refs/heads/") + 1);
	strcpy(refname, "refs/heads/");
	strcpy(refname + strlen("refs/heads/"), ret->name);
	ret->refname = refname;
 
	return ret;
}
 
static struct rewrite *make_rewrite(struct rewrites *r, const char *base, int len)
{
	struct rewrite *ret;
	int i;
 
	for (i = 0; i < r->rewrite_nr; i++) {
		if (len
		    ? (len == r->rewrite[i]->baselen &&
		       !strncmp(base, r->rewrite[i]->base, len))
		    : !strcmp(base, r->rewrite[i]->base))
			return r->rewrite[i];
	}
 
	ALLOC_GROW(r->rewrite, r->rewrite_nr + 1, r->rewrite_alloc);
	ret = xcalloc(1, sizeof(struct rewrite));
	r->rewrite[r->rewrite_nr++] = ret;
	if (len) {
		ret->base = xstrndup(base, len);
		ret->baselen = len;
	}
	else {
		ret->base = xstrdup(base);
		ret->baselen = strlen(base);
	}
	return ret;
}
 
static void add_instead_of(struct rewrite *rewrite, const char *instead_of)
{
	ALLOC_GROW(rewrite->instead_of, rewrite->instead_of_nr + 1, rewrite->instead_of_alloc);
	rewrite->instead_of[rewrite->instead_of_nr].s = instead_of;
	rewrite->instead_of[rewrite->instead_of_nr].len = strlen(instead_of);
	rewrite->instead_of_nr++;
}
 
static void read_remotes_file(struct remote *remote)
{
	FILE *f = fopen(git_path("remotes/%s", remote->name), "r");
 
	if (!f)
		return;
	remote->origin = REMOTE_REMOTES;
	while (fgets(buffer, BUF_SIZE, f)) {
		int value_list;
		char *s, *p;
 
		if (!prefixcmp(buffer, "URL:")) {
			value_list = 0;
			s = buffer + 4;
		} else if (!prefixcmp(buffer, "Push:")) {
			value_list = 1;
			s = buffer + 5;
		} else if (!prefixcmp(buffer, "Pull:")) {
			value_list = 2;
			s = buffer + 5;
		} else
			continue;
 
		while (isspace(*s))
			s++;
		if (!*s)
			continue;
 
		p = s + strlen(s);
		while (isspace(p[-1]))
			*--p = 0;
 
		switch (value_list) {
		case 0:
			add_url_alias(remote, xstrdup(s));
			break;
		case 1:
			add_push_refspec(remote, xstrdup(s));
			break;
		case 2:
			add_fetch_refspec(remote, xstrdup(s));
			break;
		}
	}
	fclose(f);
}
 
static void read_branches_file(struct remote *remote)
{
	const char *slash = strchr(remote->name, '/');
	char *frag;
	struct strbuf branch = STRBUF_INIT;
	int n = slash ? slash - remote->name : 1000;
	FILE *f = fopen(git_path("branches/%.*s", n, remote->name), "r");
	char *s, *p;
	int len;
 
	if (!f)
		return;
	s = fgets(buffer, BUF_SIZE, f);
	fclose(f);
	if (!s)
		return;
	while (isspace(*s))
		s++;
	if (!*s)
		return;
	remote->origin = REMOTE_BRANCHES;
	p = s + strlen(s);
	while (isspace(p[-1]))
		*--p = 0;
	len = p - s;
	if (slash)
		len += strlen(slash);
	p = xmalloc(len + 1);
	strcpy(p, s);
	if (slash)
		strcat(p, slash);
 
	/*
	 * With "slash", e.g. "git fetch jgarzik/netdev-2.6" when
	 * reading from $GIT_DIR/branches/jgarzik fetches "HEAD" from
	 * the partial URL obtained from the branches file plus
	 * "/netdev-2.6" and does not store it in any tracking ref.
	 * #branch specifier in the file is ignored.
	 *
	 * Otherwise, the branches file would have URL and optionally
	 * #branch specified.  The "master" (or specified) branch is
	 * fetched and stored in the local branch of the same name.
	 */
	frag = strchr(p, '#');
	if (frag) {
		*(frag++) = '\0';
		strbuf_addf(&branch, "refs/heads/%s", frag);
	} else
		strbuf_addstr(&branch, "refs/heads/master");
	if (!slash) {
		strbuf_addf(&branch, ":refs/heads/%s", remote->name);
	} else {
		strbuf_reset(&branch);
		strbuf_addstr(&branch, "HEAD:");
	}
	add_url_alias(remote, p);
	add_fetch_refspec(remote, strbuf_detach(&branch, NULL));
	/*
	 * Cogito compatible push: push current HEAD to remote #branch
	 * (master if missing)
	 */
	strbuf_init(&branch, 0);
	strbuf_addstr(&branch, "HEAD");
	if (frag)
		strbuf_addf(&branch, ":refs/heads/%s", frag);
	else
		strbuf_addstr(&branch, ":refs/heads/master");
	add_push_refspec(remote, strbuf_detach(&branch, NULL));
	remote->fetch_tags = 1; /* always auto-follow */
}
 
static int handle_config(const char *key, const char *value, void *cb)
{
	const char *name;
	const char *subkey;
	struct remote *remote;
	struct branch *branch;
	if (!prefixcmp(key, "branch.")) {
		name = key + 7;
		subkey = strrchr(name, '.');
		if (!subkey)
			return 0;
		branch = make_branch(name, subkey - name);
		if (!strcmp(subkey, ".remote")) {
			if (!value)
				return config_error_nonbool(key);
			branch->remote_name = xstrdup(value);
			if (branch == current_branch) {
				default_remote_name = branch->remote_name;
				explicit_default_remote_name = 1;
			}
		} else if (!strcmp(subkey, ".merge")) {
			if (!value)
				return config_error_nonbool(key);
			add_merge(branch, xstrdup(value));
		}
		return 0;
	}
	if (!prefixcmp(key, "url.")) {
		struct rewrite *rewrite;
		name = key + 4;
		subkey = strrchr(name, '.');
		if (!subkey)
			return 0;
		if (!strcmp(subkey, ".insteadof")) {
			rewrite = make_rewrite(&rewrites, name, subkey - name);
			if (!value)
				return config_error_nonbool(key);
			add_instead_of(rewrite, xstrdup(value));
		} else if (!strcmp(subkey, ".pushinsteadof")) {
			rewrite = make_rewrite(&rewrites_push, name, subkey - name);
			if (!value)
				return config_error_nonbool(key);
			add_instead_of(rewrite, xstrdup(value));
		}
	}
	if (prefixcmp(key,  "remote."))
		return 0;
	name = key + 7;
	if (*name == '/') {
		warning("Config remote shorthand cannot begin with '/': %s",
			name);
		return 0;
	}
	subkey = strrchr(name, '.');
	if (!subkey)
		return 0;
	remote = make_remote(name, subkey - name);
	remote->origin = REMOTE_CONFIG;
	if (!strcmp(subkey, ".mirror"))
		remote->mirror = git_config_bool(key, value);
	else if (!strcmp(subkey, ".skipdefaultupdate"))
		remote->skip_default_update = git_config_bool(key, value);
 
	else if (!strcmp(subkey, ".url")) {
		const char *v;
		if (git_config_string(&v, key, value))
			return -1;
		add_url(remote, v);
	} else if (!strcmp(subkey, ".pushurl")) {
		const char *v;
		if (git_config_string(&v, key, value))
			return -1;
		add_pushurl(remote, v);
	} else if (!strcmp(subkey, ".push")) {
		const char *v;
		if (git_config_string(&v, key, value))
			return -1;
		add_push_refspec(remote, v);
	} else if (!strcmp(subkey, ".fetch")) {
		const char *v;
		if (git_config_string(&v, key, value))
			return -1;
		add_fetch_refspec(remote, v);
	} else if (!strcmp(subkey, ".receivepack")) {
		const char *v;
		if (git_config_string(&v, key, value))
			return -1;
		if (!remote->receivepack)
			remote->receivepack = v;
		else
			error("more than one receivepack given, using the first");
	} else if (!strcmp(subkey, ".uploadpack")) {
		const char *v;
		if (git_config_string(&v, key, value))
			return -1;
		if (!remote->uploadpack)
			remote->uploadpack = v;
		else
			error("more than one uploadpack given, using the first");
	} else if (!strcmp(subkey, ".tagopt")) {
		if (!strcmp(value, "--no-tags"))
			remote->fetch_tags = -1;
	} else if (!strcmp(subkey, ".proxy")) {
		return git_config_string((const char **)&remote->http_proxy,
					 key, value);
	}
	return 0;
}
 
static void alias_all_urls(void)
{
	int i, j;
	for (i = 0; i < remotes_nr; i++) {
		int add_pushurl_aliases;
		if (!remotes[i])
			continue;
		for (j = 0; j < remotes[i]->pushurl_nr; j++) {
			remotes[i]->pushurl[j] = alias_url(remotes[i]->pushurl[j], &rewrites);
		}
		add_pushurl_aliases = remotes[i]->pushurl_nr == 0;
		for (j = 0; j < remotes[i]->url_nr; j++) {
			if (add_pushurl_aliases)
				add_pushurl_alias(remotes[i], remotes[i]->url[j]);
			remotes[i]->url[j] = alias_url(remotes[i]->url[j], &rewrites);
		}
	}
}
 
static void read_config(void)
{
	unsigned char sha1[20];
	const char *head_ref;
	int flag;
	if (default_remote_name) // did this already
		return;
	default_remote_name = xstrdup("origin");
	current_branch = NULL;
	head_ref = resolve_ref("HEAD", sha1, 0, &flag);
	if (head_ref && (flag & REF_ISSYMREF) &&
	    !prefixcmp(head_ref, "refs/heads/")) {
		current_branch =
			make_branch(head_ref + strlen("refs/heads/"), 0);
	}
	git_config(handle_config, NULL);
	alias_all_urls();
}
 
/*
 * We need to make sure the tracking branches are well formed, but a
 * wildcard refspec in "struct refspec" must have a trailing slash. We
 * temporarily drop the trailing '/' while calling check_ref_format(),
 * and put it back.  The caller knows that a CHECK_REF_FORMAT_ONELEVEL
 * error return is Ok for a wildcard refspec.
 */
static int verify_refname(char *name, int is_glob)
{
	int result;
 
	result = check_ref_format(name);
	if (is_glob && result == CHECK_REF_FORMAT_WILDCARD)
		result = CHECK_REF_FORMAT_OK;
	return result;
}
 
/*
 * This function frees a refspec array.
 * Warning: code paths should be checked to ensure that the src
 *          and dst pointers are always freeable pointers as well
 *          as the refspec pointer itself.
 */
static void free_refspecs(struct refspec *refspec, int nr_refspec)
{
	int i;
 
	if (!refspec)
		return;
 
	for (i = 0; i < nr_refspec; i++) {
		free(refspec[i].src);
		free(refspec[i].dst);
	}
	free(refspec);
}
 
static struct refspec *parse_refspec_internal(int nr_refspec, const char **refspec, int fetch, int verify)
{
	int i;
	int st;
	struct refspec *rs = xcalloc(sizeof(*rs), nr_refspec);
 
	for (i = 0; i < nr_refspec; i++) {
		size_t llen;
		int is_glob;
		const char *lhs, *rhs;
 
		is_glob = 0;
 
		lhs = refspec[i];
		if (*lhs == '+') {
			rs[i].force = 1;
			lhs++;
		}
 
		rhs = strrchr(lhs, ':');
 
		/*
		 * Before going on, special case ":" (or "+:") as a refspec
		 * for matching refs.
		 */
		if (!fetch && rhs == lhs && rhs[1] == '\0') {
			rs[i].matching = 1;
			continue;
		}
 
		if (rhs) {
			size_t rlen = strlen(++rhs);
			is_glob = (1 <= rlen && strchr(rhs, '*'));
			rs[i].dst = xstrndup(rhs, rlen);
		}
 
		llen = (rhs ? (rhs - lhs - 1) : strlen(lhs));
		if (1 <= llen && memchr(lhs, '*', llen)) {
			if ((rhs && !is_glob) || (!rhs && fetch))
				goto invalid;
			is_glob = 1;
		} else if (rhs && is_glob) {
			goto invalid;
		}
 
		rs[i].pattern = is_glob;
		rs[i].src = xstrndup(lhs, llen);
 
		if (fetch) {
			/*
			 * LHS
			 * - empty is allowed; it means HEAD.
			 * - otherwise it must be a valid looking ref.
			 */
			if (!*rs[i].src)
				; /* empty is ok */
			else {
				st = verify_refname(rs[i].src, is_glob);
				if (st && st != CHECK_REF_FORMAT_ONELEVEL)
					goto invalid;
			}
			/*
			 * RHS
			 * - missing is ok, and is same as empty.
			 * - empty is ok; it means not to store.
			 * - otherwise it must be a valid looking ref.
			 */
			if (!rs[i].dst) {
				; /* ok */
			} else if (!*rs[i].dst) {
				; /* ok */
			} else {
				st = verify_refname(rs[i].dst, is_glob);
				if (st && st != CHECK_REF_FORMAT_ONELEVEL)
					goto invalid;
			}
		} else {
			/*
			 * LHS
			 * - empty is allowed; it means delete.
			 * - when wildcarded, it must be a valid looking ref.
			 * - otherwise, it must be an extended SHA-1, but
			 *   there is no existing way to validate this.
			 */
			if (!*rs[i].src)
				; /* empty is ok */
			else if (is_glob) {
				st = verify_refname(rs[i].src, is_glob);
				if (st && st != CHECK_REF_FORMAT_ONELEVEL)
					goto invalid;
			}
			else
				; /* anything goes, for now */
			/*
			 * RHS
			 * - missing is allowed, but LHS then must be a
			 *   valid looking ref.
			 * - empty is not allowed.
			 * - otherwise it must be a valid looking ref.
			 */
			if (!rs[i].dst) {
				st = verify_refname(rs[i].src, is_glob);
				if (st && st != CHECK_REF_FORMAT_ONELEVEL)
					goto invalid;
			} else if (!*rs[i].dst) {
				goto invalid;
			} else {
				st = verify_refname(rs[i].dst, is_glob);
				if (st && st != CHECK_REF_FORMAT_ONELEVEL)
					goto invalid;
			}
		}
	}
	return rs;
 
 invalid:
	if (verify) {
		/*
		 * nr_refspec must be greater than zero and i must be valid
		 * since it is only possible to reach this point from within
		 * the for loop above.
		 */
		free_refspecs(rs, i+1);
		return NULL;
	}
	die("Invalid refspec '%s'", refspec[i]);
}
 
int valid_fetch_refspec(const char *fetch_refspec_str)
{
	const char *fetch_refspec[] = { fetch_refspec_str };
	struct refspec *refspec;
 
	refspec = parse_refspec_internal(1, fetch_refspec, 1, 1);
	free_refspecs(refspec, 1);
	return !!refspec;
}
 
struct refspec *parse_fetch_refspec(int nr_refspec, const char **refspec)
{
	return parse_refspec_internal(nr_refspec, refspec, 1, 0);
}
 
static struct refspec *parse_push_refspec(int nr_refspec, const char **refspec)
{
	return parse_refspec_internal(nr_refspec, refspec, 0, 0);
}
 
static int valid_remote_nick(const char *name)
{
	if (!name[0] || is_dot_or_dotdot(name))
		return 0;
	return !strchr(name, '/'); /* no slash */
}
 
struct remote *remote_get(const char *name)
{
	struct remote *ret;
	int name_given = 0;
 
	read_config();
	if (name)
		name_given = 1;
	else {
		name = default_remote_name;
		name_given = explicit_default_remote_name;
	}
 
	ret = make_remote(name, 0);
	if (valid_remote_nick(name)) {
		if (!ret->url)
			read_remotes_file(ret);
		if (!ret->url)
			read_branches_file(ret);
	}
	if (name_given && !ret->url)
		add_url_alias(ret, name);
	if (!ret->url)
		return NULL;
	ret->fetch = parse_fetch_refspec(ret->fetch_refspec_nr, ret->fetch_refspec);
	ret->push = parse_push_refspec(ret->push_refspec_nr, ret->push_refspec);
	return ret;
}
 
int remote_is_configured(const char *name)
{
	int i;
	read_config();
 
	for (i = 0; i < remotes_nr; i++)
		if (!strcmp(name, remotes[i]->name))
			return 1;
	return 0;
}
 
int for_each_remote(each_remote_fn fn, void *priv)
{
	int i, result = 0;
	read_config();
	for (i = 0; i < remotes_nr && !result; i++) {
		struct remote *r = remotes[i];
		if (!r)
			continue;
		if (!r->fetch)
			r->fetch = parse_fetch_refspec(r->fetch_refspec_nr,
						       r->fetch_refspec);
		if (!r->push)
			r->push = parse_push_refspec(r->push_refspec_nr,
						     r->push_refspec);
		result = fn(r, priv);
	}
	return result;
}
 
void ref_remove_duplicates(struct ref *ref_map)
{
	struct ref **posn;
	struct ref *next;
	for (; ref_map; ref_map = ref_map->next) {
		if (!ref_map->peer_ref)
			continue;
		posn = &ref_map->next;
		while (*posn) {
			if ((*posn)->peer_ref &&
			    !strcmp((*posn)->peer_ref->name,
				    ref_map->peer_ref->name)) {
				if (strcmp((*posn)->name, ref_map->name))
					die("%s tracks both %s and %s",
					    ref_map->peer_ref->name,
					    (*posn)->name, ref_map->name);
				next = (*posn)->next;
				free((*posn)->peer_ref);
				free(*posn);
				*posn = next;
			} else {
				posn = &(*posn)->next;
			}
		}
	}
}
 
int remote_has_url(struct remote *remote, const char *url)
{
	int i;
	for (i = 0; i < remote->url_nr; i++) {
		if (!strcmp(remote->url[i], url))
			return 1;
	}
	return 0;
}
 
static int match_name_with_pattern(const char *key, const char *name,
				   const char *value, char **result)
{
	const char *kstar = strchr(key, '*');
	size_t klen;
	size_t ksuffixlen;
	size_t namelen;
	int ret;
	if (!kstar)
		die("Key '%s' of pattern had no '*'", key);
	klen = kstar - key;
	ksuffixlen = strlen(kstar + 1);
	namelen = strlen(name);
	ret = !strncmp(name, key, klen) && namelen >= klen + ksuffixlen &&
		!memcmp(name + namelen - ksuffixlen, kstar + 1, ksuffixlen);
	if (ret && value) {
		const char *vstar = strchr(value, '*');
		size_t vlen;
		size_t vsuffixlen;
		if (!vstar)
			die("Value '%s' of pattern has no '*'", value);
		vlen = vstar - value;
		vsuffixlen = strlen(vstar + 1);
		*result = xmalloc(vlen + vsuffixlen +
				  strlen(name) -
				  klen - ksuffixlen + 1);
		strncpy(*result, value, vlen);
		strncpy(*result + vlen,
			name + klen, namelen - klen - ksuffixlen);
		strcpy(*result + vlen + namelen - klen - ksuffixlen,
		       vstar + 1);
	}
	return ret;
}
 
int remote_find_tracking(struct remote *remote, struct refspec *refspec)
{
	int find_src = refspec->src == NULL;
	char *needle, **result;
	int i;
 
	if (find_src) {
		if (!refspec->dst)
			return error("find_tracking: need either src or dst");
		needle = refspec->dst;
		result = &refspec->src;
	} else {
		needle = refspec->src;
		result = &refspec->dst;
	}
 
	for (i = 0; i < remote->fetch_refspec_nr; i++) {
		struct refspec *fetch = &remote->fetch[i];
		const char *key = find_src ? fetch->dst : fetch->src;
		const char *value = find_src ? fetch->src : fetch->dst;
		if (!fetch->dst)
			continue;
		if (fetch->pattern) {
			if (match_name_with_pattern(key, needle, value, result)) {
				refspec->force = fetch->force;
				return 0;
			}
		} else if (!strcmp(needle, key)) {
			*result = xstrdup(value);
			refspec->force = fetch->force;
			return 0;
		}
	}
	return -1;
}
 
static struct ref *alloc_ref_with_prefix(const char *prefix, size_t prefixlen,
		const char *name)
{
	size_t len = strlen(name);
	struct ref *ref = xcalloc(1, sizeof(struct ref) + prefixlen + len + 1);
	memcpy(ref->name, prefix, prefixlen);
	memcpy(ref->name + prefixlen, name, len);
	return ref;
}
 
struct ref *alloc_ref(const char *name)
{
	return alloc_ref_with_prefix("", 0, name);
}
 
static struct ref *copy_ref(const struct ref *ref)
{
	struct ref *cpy;
	size_t len;
	if (!ref)
		return NULL;
	len = strlen(ref->name);
	cpy = xmalloc(sizeof(struct ref) + len + 1);
	memcpy(cpy, ref, sizeof(struct ref) + len + 1);
	cpy->next = NULL;
	cpy->symref = ref->symref ? xstrdup(ref->symref) : NULL;
	cpy->remote_status = ref->remote_status ? xstrdup(ref->remote_status) : NULL;
	cpy->peer_ref = copy_ref(ref->peer_ref);
	return cpy;
}
 
struct ref *copy_ref_list(const struct ref *ref)
{
	struct ref *ret = NULL;
	struct ref **tail = &ret;
	while (ref) {
		*tail = copy_ref(ref);
		ref = ref->next;
		tail = &((*tail)->next);
	}
	return ret;
}
 
static void free_ref(struct ref *ref)
{
	if (!ref)
		return;
	free_ref(ref->peer_ref);
	free(ref->remote_status);
	free(ref->symref);
	free(ref);
}
 
void free_refs(struct ref *ref)
{
	struct ref *next;
	while (ref) {
		next = ref->next;
		free_ref(ref);
		ref = next;
	}
}
 
static int count_refspec_match(const char *pattern,
			       struct ref *refs,
			       struct ref **matched_ref)
{
	int patlen = strlen(pattern);
	struct ref *matched_weak = NULL;
	struct ref *matched = NULL;
	int weak_match = 0;
	int match = 0;
 
	for (weak_match = match = 0; refs; refs = refs->next) {
		char *name = refs->name;
		int namelen = strlen(name);
 
		if (!refname_match(pattern, name, ref_rev_parse_rules))
			continue;
 
		/* A match is "weak" if it is with refs outside
		 * heads or tags, and did not specify the pattern
		 * in full (e.g. "refs/remotes/origin/master") or at
		 * least from the toplevel (e.g. "remotes/origin/master");
		 * otherwise "git push $URL master" would result in
		 * ambiguity between remotes/origin/master and heads/master
		 * at the remote site.
		 */
		if (namelen != patlen &&
		    patlen != namelen - 5 &&
		    prefixcmp(name, "refs/heads/") &&
		    prefixcmp(name, "refs/tags/")) {
			/* We want to catch the case where only weak
			 * matches are found and there are multiple
			 * matches, and where more than one strong
			 * matches are found, as ambiguous.  One
			 * strong match with zero or more weak matches
			 * are acceptable as a unique match.
			 */
			matched_weak = refs;
			weak_match++;
		}
		else {
			matched = refs;
			match++;
		}
	}
	if (!matched) {
		*matched_ref = matched_weak;
		return weak_match;
	}
	else {
		*matched_ref = matched;
		return match;
	}
}
 
static void tail_link_ref(struct ref *ref, struct ref ***tail)
{
	**tail = ref;
	while (ref->next)
		ref = ref->next;
	*tail = &ref->next;
}
 
static struct ref *try_explicit_object_name(const char *name)
{
	unsigned char sha1[20];
	struct ref *ref;
 
	if (!*name) {
		ref = alloc_ref("(delete)");
		hashclr(ref->new_sha1);
		return ref;
	}
	if (get_sha1(name, sha1))
		return NULL;
	ref = alloc_ref(name);
	hashcpy(ref->new_sha1, sha1);
	return ref;
}
 
static struct ref *make_linked_ref(const char *name, struct ref ***tail)
{
	struct ref *ret = alloc_ref(name);
	tail_link_ref(ret, tail);
	return ret;
}
 
static char *guess_ref(const char *name, struct ref *peer)
{
	struct strbuf buf = STRBUF_INIT;
	unsigned char sha1[20];
 
	const char *r = resolve_ref(peer->name, sha1, 1, NULL);
	if (!r)
		return NULL;
 
	if (!prefixcmp(r, "refs/heads/"))
		strbuf_addstr(&buf, "refs/heads/");
	else if (!prefixcmp(r, "refs/tags/"))
		strbuf_addstr(&buf, "refs/tags/");
	else
		return NULL;
 
	strbuf_addstr(&buf, name);
	return strbuf_detach(&buf, NULL);
}
 
static int match_explicit(struct ref *src, struct ref *dst,
			  struct ref ***dst_tail,
			  struct refspec *rs)
{
	struct ref *matched_src, *matched_dst;
	int copy_src;
 
	const char *dst_value = rs->dst;
	char *dst_guess;
 
	if (rs->pattern || rs->matching)
		return 0;
 
	matched_src = matched_dst = NULL;
	switch (count_refspec_match(rs->src, src, &matched_src)) {
	case 1:
		copy_src = 1;
		break;
	case 0:
		/* The source could be in the get_sha1() format
		 * not a reference name.  :refs/other is a
		 * way to delete 'other' ref at the remote end.
		 */
		matched_src = try_explicit_object_name(rs->src);
		if (!matched_src)
			return error("src refspec %s does not match any.", rs->src);
		copy_src = 0;
		break;
	default:
		return error("src refspec %s matches more than one.", rs->src);
	}
 
	if (!dst_value) {
		unsigned char sha1[20];
		int flag;
 
		dst_value = resolve_ref(matched_src->name, sha1, 1, &flag);
		if (!dst_value ||
		    ((flag & REF_ISSYMREF) &&
		     prefixcmp(dst_value, "refs/heads/")))
			die("%s cannot be resolved to branch.",
			    matched_src->name);
	}
 
	switch (count_refspec_match(dst_value, dst, &matched_dst)) {
	case 1:
		break;
	case 0:
		if (!memcmp(dst_value, "refs/", 5))
			matched_dst = make_linked_ref(dst_value, dst_tail);
		else if ((dst_guess = guess_ref(dst_value, matched_src)))
			matched_dst = make_linked_ref(dst_guess, dst_tail);
		else
			error("unable to push to unqualified destination: %s\n"
			      "The destination refspec neither matches an "
			      "existing ref on the remote nor\n"
			      "begins with refs/, and we are unable to "
			      "guess a prefix based on the source ref.",
			      dst_value);
		break;
	default:
		matched_dst = NULL;
		error("dst refspec %s matches more than one.",
		      dst_value);
		break;
	}
	if (!matched_dst)
		return -1;
	if (matched_dst->peer_ref)
		return error("dst ref %s receives from more than one src.",
		      matched_dst->name);
	else {
		matched_dst->peer_ref = copy_src ? copy_ref(matched_src) : matched_src;
		matched_dst->force = rs->force;
	}
	return 0;
}
 
static int match_explicit_refs(struct ref *src, struct ref *dst,
			       struct ref ***dst_tail, struct refspec *rs,
			       int rs_nr)
{
	int i, errs;
	for (i = errs = 0; i < rs_nr; i++)
		errs += match_explicit(src, dst, dst_tail, &rs[i]);
	return errs;
}
 
static const struct refspec *check_pattern_match(const struct refspec *rs,
						 int rs_nr,
						 const struct ref *src)
{
	int i;
	int matching_refs = -1;
	for (i = 0; i < rs_nr; i++) {
		if (rs[i].matching &&
		    (matching_refs == -1 || rs[i].force)) {
			matching_refs = i;
			continue;
		}
 
		if (rs[i].pattern && match_name_with_pattern(rs[i].src, src->name,
							     NULL, NULL))
			return rs + i;
	}
	if (matching_refs != -1)
		return rs + matching_refs;
	else
		return NULL;
}
 
static struct ref **tail_ref(struct ref **head)
{
	struct ref **tail = head;
	while (*tail)
		tail = &((*tail)->next);
	return tail;
}
 
/*
 * Note. This is used only by "push"; refspec matching rules for
 * push and fetch are subtly different, so do not try to reuse it
 * without thinking.
 */
int match_refs(struct ref *src, struct ref **dst,
	       int nr_refspec, const char **refspec, int flags)
{
	struct refspec *rs;
	int send_all = flags & MATCH_REFS_ALL;
	int send_mirror = flags & MATCH_REFS_MIRROR;
	int errs;
	static const char *default_refspec[] = { ":", NULL };
	struct ref **dst_tail = tail_ref(dst);
 
	if (!nr_refspec) {
		nr_refspec = 1;
		refspec = default_refspec;
	}
	rs = parse_push_refspec(nr_refspec, (const char **) refspec);
	errs = match_explicit_refs(src, *dst, &dst_tail, rs, nr_refspec);
 
	/* pick the remainder */
	for ( ; src; src = src->next) {
		struct ref *dst_peer;
		const struct refspec *pat = NULL;
		char *dst_name;
		if (src->peer_ref)
			continue;
 
		pat = check_pattern_match(rs, nr_refspec, src);
		if (!pat)
			continue;
 
		if (pat->matching) {
			/*
			 * "matching refs"; traditionally we pushed everything
			 * including refs outside refs/heads/ hierarchy, but
			 * that does not make much sense these days.
			 */
			if (!send_mirror && prefixcmp(src->name, "refs/heads/"))
				continue;
			dst_name = xstrdup(src->name);
 
		} else {
			const char *dst_side = pat->dst ? pat->dst : pat->src;
			if (!match_name_with_pattern(pat->src, src->name,
						     dst_side, &dst_name))
				die("Didn't think it matches any more");
		}
		dst_peer = find_ref_by_name(*dst, dst_name);
		if (dst_peer) {
			if (dst_peer->peer_ref)
				/* We're already sending something to this ref. */
				goto free_name;
 
		} else {
			if (pat->matching && !(send_all || send_mirror))
				/*
				 * Remote doesn't have it, and we have no
				 * explicit pattern, and we don't have
				 * --all nor --mirror.
				 */
				goto free_name;
 
			/* Create a new one and link it */
			dst_peer = make_linked_ref(dst_name, &dst_tail);
			hashcpy(dst_peer->new_sha1, src->new_sha1);
		}
		dst_peer->peer_ref = copy_ref(src);
		dst_peer->force = pat->force;
	free_name:
		free(dst_name);
	}
	if (errs)
		return -1;
	return 0;
}
 
struct branch *branch_get(const char *name)
{
	struct branch *ret;
 
	read_config();
	if (!name || !*name || !strcmp(name, "HEAD"))
		ret = current_branch;
	else
		ret = make_branch(name, 0);
	if (ret && ret->remote_name) {
		ret->remote = remote_get(ret->remote_name);
		if (ret->merge_nr) {
			int i;
			ret->merge = xcalloc(sizeof(*ret->merge),
					     ret->merge_nr);
			for (i = 0; i < ret->merge_nr; i++) {
				ret->merge[i] = xcalloc(1, sizeof(**ret->merge));
				ret->merge[i]->src = xstrdup(ret->merge_name[i]);
				if (remote_find_tracking(ret->remote, ret->merge[i])
				    && !strcmp(ret->remote_name, "."))
					ret->merge[i]->dst = xstrdup(ret->merge_name[i]);
			}
		}
	}
	return ret;
}
 
int branch_has_merge_config(struct branch *branch)
{
	return branch && !!branch->merge;
}
 
int branch_merge_matches(struct branch *branch,
		                 int i,
		                 const char *refname)
{
	if (!branch || i < 0 || i >= branch->merge_nr)
		return 0;
	return refname_match(branch->merge[i]->src, refname, ref_fetch_rules);
}
 
static struct ref *get_expanded_map(const struct ref *remote_refs,
				    const struct refspec *refspec)
{
	const struct ref *ref;
	struct ref *ret = NULL;
	struct ref **tail = &ret;
 
	char *expn_name;
 
	for (ref = remote_refs; ref; ref = ref->next) {
		if (strchr(ref->name, '^'))
			continue; /* a dereference item */
		if (match_name_with_pattern(refspec->src, ref->name,
					    refspec->dst, &expn_name)) {
			struct ref *cpy = copy_ref(ref);
 
			cpy->peer_ref = alloc_ref(expn_name);
			free(expn_name);
			if (refspec->force)
				cpy->peer_ref->force = 1;
			*tail = cpy;
			tail = &cpy->next;
		}
	}
 
	return ret;
}
 
static const struct ref *find_ref_by_name_abbrev(const struct ref *refs, const char *name)
{
	const struct ref *ref;
	for (ref = refs; ref; ref = ref->next) {
		if (refname_match(name, ref->name, ref_fetch_rules))
			return ref;
	}
	return NULL;
}
 
struct ref *get_remote_ref(const struct ref *remote_refs, const char *name)
{
	const struct ref *ref = find_ref_by_name_abbrev(remote_refs, name);
 
	if (!ref)
		return NULL;
 
	return copy_ref(ref);
}
 
static struct ref *get_local_ref(const char *name)
{
	if (!name || name[0] == '\0')
		return NULL;
 
	if (!prefixcmp(name, "refs/"))
		return alloc_ref(name);
 
	if (!prefixcmp(name, "heads/") ||
	    !prefixcmp(name, "tags/") ||
	    !prefixcmp(name, "remotes/"))
		return alloc_ref_with_prefix("refs/", 5, name);
 
	return alloc_ref_with_prefix("refs/heads/", 11, name);
}
 
int get_fetch_map(const struct ref *remote_refs,
		  const struct refspec *refspec,
		  struct ref ***tail,
		  int missing_ok)
{
	struct ref *ref_map, **rmp;
 
	if (refspec->pattern) {
		ref_map = get_expanded_map(remote_refs, refspec);
	} else {
		const char *name = refspec->src[0] ? refspec->src : "HEAD";
 
		ref_map = get_remote_ref(remote_refs, name);
		if (!missing_ok && !ref_map)
			die("Couldn't find remote ref %s", name);
		if (ref_map) {
			ref_map->peer_ref = get_local_ref(refspec->dst);
			if (ref_map->peer_ref && refspec->force)
				ref_map->peer_ref->force = 1;
		}
	}
 
	for (rmp = &ref_map; *rmp; ) {
		if ((*rmp)->peer_ref) {
			int st = check_ref_format((*rmp)->peer_ref->name + 5);
			if (st && st != CHECK_REF_FORMAT_ONELEVEL) {
				struct ref *ignore = *rmp;
				error("* Ignoring funny ref '%s' locally",
				      (*rmp)->peer_ref->name);
				*rmp = (*rmp)->next;
				free(ignore->peer_ref);
				free(ignore);
				continue;
			}
		}
		rmp = &((*rmp)->next);
	}
 
	if (ref_map)
		tail_link_ref(ref_map, tail);
 
	return 0;
}
 
int resolve_remote_symref(struct ref *ref, struct ref *list)
{
	if (!ref->symref)
		return 0;
	for (; list; list = list->next)
		if (!strcmp(ref->symref, list->name)) {
			hashcpy(ref->old_sha1, list->old_sha1);
			return 0;
		}
	return 1;
}
 
static void unmark_and_free(struct commit_list *list, unsigned int mark)
{
	while (list) {
		struct commit_list *temp = list;
		temp->item->object.flags &= ~mark;
		list = temp->next;
		free(temp);
	}
}
 
int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
{
	struct object *o;
	struct commit *old, *new;
	struct commit_list *list, *used;
	int found = 0;
 
	/* Both new and old must be commit-ish and new is descendant of
	 * old.  Otherwise we require --force.
	 */
	o = deref_tag(parse_object(old_sha1), NULL, 0);
	if (!o || o->type != OBJ_COMMIT)
		return 0;
	old = (struct commit *) o;
 
	o = deref_tag(parse_object(new_sha1), NULL, 0);
	if (!o || o->type != OBJ_COMMIT)
		return 0;
	new = (struct commit *) o;
 
	if (parse_commit(new) < 0)
		return 0;
 
	used = list = NULL;
	commit_list_insert(new, &list);
	while (list) {
		new = pop_most_recent_commit(&list, TMP_MARK);
		commit_list_insert(new, &used);
		if (new == old) {
			found = 1;
			break;
		}
	}
	unmark_and_free(list, TMP_MARK);
	unmark_and_free(used, TMP_MARK);
	return found;
}
 
/*
 * Return true if there is anything to report, otherwise false.
 */
int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
{
	unsigned char sha1[20];
	struct commit *ours, *theirs;
	char symmetric[84];
	struct rev_info revs;
	const char *rev_argv[10], *base;
	int rev_argc;
 
	/*
	 * Nothing to report unless we are marked to build on top of
	 * somebody else.
	 */
	if (!branch ||
	    !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
		return 0;
 
	/*
	 * If what we used to build on no longer exists, there is
	 * nothing to report.
	 */
	base = branch->merge[0]->dst;
	if (!resolve_ref(base, sha1, 1, NULL))
		return 0;
	theirs = lookup_commit_reference(sha1);
	if (!theirs)
		return 0;
 
	if (!resolve_ref(branch->refname, sha1, 1, NULL))
		return 0;
	ours = lookup_commit_reference(sha1);
	if (!ours)
		return 0;
 
	/* are we the same? */
	if (theirs == ours)
		return 0;
 
	/* Run "rev-list --left-right ours...theirs" internally... */
	rev_argc = 0;
	rev_argv[rev_argc++] = NULL;
	rev_argv[rev_argc++] = "--left-right";
	rev_argv[rev_argc++] = symmetric;
	rev_argv[rev_argc++] = "--";
	rev_argv[rev_argc] = NULL;
 
	strcpy(symmetric, sha1_to_hex(ours->object.sha1));
	strcpy(symmetric + 40, "...");
	strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
 
	init_revisions(&revs, NULL);
	setup_revisions(rev_argc, rev_argv, &revs, NULL);
	prepare_revision_walk(&revs);
 
	/* ... and count the commits on each side. */
	*num_ours = 0;
	*num_theirs = 0;
	while (1) {
		struct commit *c = get_revision(&revs);
		if (!c)
			break;
		if (c->object.flags & SYMMETRIC_LEFT)
			(*num_ours)++;
		else
			(*num_theirs)++;
	}
 
	/* clear object flags smudged by the above traversal */
	clear_commit_marks(ours, ALL_REV_FLAGS);
	clear_commit_marks(theirs, ALL_REV_FLAGS);
	return 1;
}
 
/*
 * Return true when there is anything to report, otherwise false.
 */
int format_tracking_info(struct branch *branch, struct strbuf *sb)
{
	int num_ours, num_theirs;
	const char *base;
 
	if (!stat_tracking_info(branch, &num_ours, &num_theirs))
		return 0;
 
	base = branch->merge[0]->dst;
	base = shorten_unambiguous_ref(base, 0);
	if (!num_theirs)
		strbuf_addf(sb, "Your branch is ahead of '%s' "
			    "by %d commit%s.\n",
			    base, num_ours, (num_ours == 1) ? "" : "s");
	else if (!num_ours)
		strbuf_addf(sb, "Your branch is behind '%s' "
			    "by %d commit%s, "
			    "and can be fast-forwarded.\n",
			    base, num_theirs, (num_theirs == 1) ? "" : "s");
	else
		strbuf_addf(sb, "Your branch and '%s' have diverged,\n"
			    "and have %d and %d different commit(s) each, "
			    "respectively.\n",
			    base, num_ours, num_theirs);
	return 1;
}
 
static int one_local_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
{
	struct ref ***local_tail = cb_data;
	struct ref *ref;
	int len;
 
	/* we already know it starts with refs/ to get here */
	if (check_ref_format(refname + 5))
		return 0;
 
	len = strlen(refname) + 1;
	ref = xcalloc(1, sizeof(*ref) + len);
	hashcpy(ref->new_sha1, sha1);
	memcpy(ref->name, refname, len);
	**local_tail = ref;
	*local_tail = &ref->next;
	return 0;
}
 
struct ref *get_local_heads(void)
{
	struct ref *local_refs = NULL, **local_tail = &local_refs;
	for_each_ref(one_local_ref, &local_tail);
	return local_refs;
}
 
struct ref *guess_remote_head(const struct ref *head,
			      const struct ref *refs,
			      int all)
{
	const struct ref *r;
	struct ref *list = NULL;
	struct ref **tail = &list;
 
	if (!head)
		return NULL;
 
	/*
	 * Some transports support directly peeking at
	 * where HEAD points; if that is the case, then
	 * we don't have to guess.
	 */
	if (head->symref)
		return copy_ref(find_ref_by_name(refs, head->symref));
 
	/* If refs/heads/master could be right, it is. */
	if (!all) {
		r = find_ref_by_name(refs, "refs/heads/master");
		if (r && !hashcmp(r->old_sha1, head->old_sha1))
			return copy_ref(r);
	}
 
	/* Look for another ref that points there */
	for (r = refs; r; r = r->next) {
		if (r != head && !hashcmp(r->old_sha1, head->old_sha1)) {
			*tail = copy_ref(r);
			tail = &((*tail)->next);
			if (!all)
				break;
		}
	}
 
	return list;
}