summaryrefslogtreecommitdiff
path: root/builtin/receive-pack.c
blob: 6420680bddcd4d9963f5b71e98b09ff5528ec42d (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 "builtin.h"
#include "lockfile.h"
#include "pack.h"
#include "refs.h"
#include "pkt-line.h"
#include "sideband.h"
#include "run-command.h"
#include "exec_cmd.h"
#include "commit.h"
#include "object.h"
#include "remote.h"
#include "connect.h"
#include "transport.h"
#include "string-list.h"
#include "sha1-array.h"
#include "connected.h"
#include "argv-array.h"
#include "version.h"
#include "tag.h"
#include "gpg-interface.h"
#include "sigchain.h"
 
static const char receive_pack_usage[] = "git receive-pack <git-dir>";
 
enum deny_action {
	DENY_UNCONFIGURED,
	DENY_IGNORE,
	DENY_WARN,
	DENY_REFUSE
};
 
static int deny_deletes;
static int deny_non_fast_forwards;
static enum deny_action deny_current_branch = DENY_UNCONFIGURED;
static enum deny_action deny_delete_current = DENY_UNCONFIGURED;
static int receive_fsck_objects = -1;
static int transfer_fsck_objects = -1;
static int receive_unpack_limit = -1;
static int transfer_unpack_limit = -1;
static int unpack_limit = 100;
static int report_status;
static int use_sideband;
static int quiet;
static int prefer_ofs_delta = 1;
static int auto_update_server_info;
static int auto_gc = 1;
static int fix_thin = 1;
static int stateless_rpc;
static const char *service_dir;
static const char *head_name;
static void *head_name_to_free;
static int sent_capabilities;
static int shallow_update;
static const char *alt_shallow_file;
static struct strbuf push_cert = STRBUF_INIT;
static unsigned char push_cert_sha1[20];
static struct signature_check sigcheck;
static const char *push_cert_nonce;
static const char *cert_nonce_seed;
 
static const char *NONCE_UNSOLICITED = "UNSOLICITED";
static const char *NONCE_BAD = "BAD";
static const char *NONCE_MISSING = "MISSING";
static const char *NONCE_OK = "OK";
static const char *NONCE_SLOP = "SLOP";
static const char *nonce_status;
static long nonce_stamp_slop;
static unsigned long nonce_stamp_slop_limit;
 
static enum deny_action parse_deny_action(const char *var, const char *value)
{
	if (value) {
		if (!strcasecmp(value, "ignore"))
			return DENY_IGNORE;
		if (!strcasecmp(value, "warn"))
			return DENY_WARN;
		if (!strcasecmp(value, "refuse"))
			return DENY_REFUSE;
	}
	if (git_config_bool(var, value))
		return DENY_REFUSE;
	return DENY_IGNORE;
}
 
static int receive_pack_config(const char *var, const char *value, void *cb)
{
	int status = parse_hide_refs_config(var, value, "receive");
 
	if (status)
		return status;
 
	if (strcmp(var, "receive.denydeletes") == 0) {
		deny_deletes = git_config_bool(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.denynonfastforwards") == 0) {
		deny_non_fast_forwards = git_config_bool(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.unpacklimit") == 0) {
		receive_unpack_limit = git_config_int(var, value);
		return 0;
	}
 
	if (strcmp(var, "transfer.unpacklimit") == 0) {
		transfer_unpack_limit = git_config_int(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.fsckobjects") == 0) {
		receive_fsck_objects = git_config_bool(var, value);
		return 0;
	}
 
	if (strcmp(var, "transfer.fsckobjects") == 0) {
		transfer_fsck_objects = git_config_bool(var, value);
		return 0;
	}
 
	if (!strcmp(var, "receive.denycurrentbranch")) {
		deny_current_branch = parse_deny_action(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.denydeletecurrent") == 0) {
		deny_delete_current = parse_deny_action(var, value);
		return 0;
	}
 
	if (strcmp(var, "repack.usedeltabaseoffset") == 0) {
		prefer_ofs_delta = git_config_bool(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.updateserverinfo") == 0) {
		auto_update_server_info = git_config_bool(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.autogc") == 0) {
		auto_gc = git_config_bool(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.shallowupdate") == 0) {
		shallow_update = git_config_bool(var, value);
		return 0;
	}
 
	if (strcmp(var, "receive.certnonceseed") == 0)
		return git_config_string(&cert_nonce_seed, var, value);
 
	if (strcmp(var, "receive.certnonceslop") == 0) {
		nonce_stamp_slop_limit = git_config_ulong(var, value);
		return 0;
	}
 
	return git_default_config(var, value, cb);
}
 
static void show_ref(const char *path, const unsigned char *sha1)
{
	if (ref_is_hidden(path))
		return;
 
	if (sent_capabilities) {
		packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
	} else {
		struct strbuf cap = STRBUF_INIT;
 
		strbuf_addstr(&cap,
			      "report-status delete-refs side-band-64k quiet");
		if (prefer_ofs_delta)
			strbuf_addstr(&cap, " ofs-delta");
		if (push_cert_nonce)
			strbuf_addf(&cap, " push-cert=%s", push_cert_nonce);
		strbuf_addf(&cap, " agent=%s", git_user_agent_sanitized());
		packet_write(1, "%s %s%c%s\n",
			     sha1_to_hex(sha1), path, 0, cap.buf);
		strbuf_release(&cap);
		sent_capabilities = 1;
	}
}
 
static int show_ref_cb(const char *path, const unsigned char *sha1, int flag, void *unused)
{
	path = strip_namespace(path);
	/*
	 * Advertise refs outside our current namespace as ".have"
	 * refs, so that the client can use them to minimize data
	 * transfer but will otherwise ignore them. This happens to
	 * cover ".have" that are thrown in by add_one_alternate_ref()
	 * to mark histories that are complete in our alternates as
	 * well.
	 */
	if (!path)
		path = ".have";
	show_ref(path, sha1);
	return 0;
}
 
static void show_one_alternate_sha1(const unsigned char sha1[20], void *unused)
{
	show_ref(".have", sha1);
}
 
static void collect_one_alternate_ref(const struct ref *ref, void *data)
{
	struct sha1_array *sa = data;
	sha1_array_append(sa, ref->old_sha1);
}
 
static void write_head_info(void)
{
	struct sha1_array sa = SHA1_ARRAY_INIT;
	for_each_alternate_ref(collect_one_alternate_ref, &sa);
	sha1_array_for_each_unique(&sa, show_one_alternate_sha1, NULL);
	sha1_array_clear(&sa);
	for_each_ref(show_ref_cb, NULL);
	if (!sent_capabilities)
		show_ref("capabilities^{}", null_sha1);
 
	advertise_shallow_grafts(1);
 
	/* EOF */
	packet_flush(1);
}
 
struct command {
	struct command *next;
	const char *error_string;
	unsigned int skip_update:1,
		     did_not_exist:1;
	int index;
	unsigned char old_sha1[20];
	unsigned char new_sha1[20];
	char ref_name[FLEX_ARRAY]; /* more */
};
 
static void rp_error(const char *err, ...) __attribute__((format (printf, 1, 2)));
static void rp_warning(const char *err, ...) __attribute__((format (printf, 1, 2)));
 
static void report_message(const char *prefix, const char *err, va_list params)
{
	int sz = strlen(prefix);
	char msg[4096];
 
	strncpy(msg, prefix, sz);
	sz += vsnprintf(msg + sz, sizeof(msg) - sz, err, params);
	if (sz > (sizeof(msg) - 1))
		sz = sizeof(msg) - 1;
	msg[sz++] = '\n';
 
	if (use_sideband)
		send_sideband(1, 2, msg, sz, use_sideband);
	else
		xwrite(2, msg, sz);
}
 
static void rp_warning(const char *err, ...)
{
	va_list params;
	va_start(params, err);
	report_message("warning: ", err, params);
	va_end(params);
}
 
static void rp_error(const char *err, ...)
{
	va_list params;
	va_start(params, err);
	report_message("error: ", err, params);
	va_end(params);
}
 
static int copy_to_sideband(int in, int out, void *arg)
{
	char data[128];
	while (1) {
		ssize_t sz = xread(in, data, sizeof(data));
		if (sz <= 0)
			break;
		send_sideband(1, 2, data, sz, use_sideband);
	}
	close(in);
	return 0;
}
 
#define HMAC_BLOCK_SIZE 64
 
static void hmac_sha1(unsigned char *out,
		      const char *key_in, size_t key_len,
		      const char *text, size_t text_len)
{
	unsigned char key[HMAC_BLOCK_SIZE];
	unsigned char k_ipad[HMAC_BLOCK_SIZE];
	unsigned char k_opad[HMAC_BLOCK_SIZE];
	int i;
	git_SHA_CTX ctx;
 
	/* RFC 2104 2. (1) */
	memset(key, '\0', HMAC_BLOCK_SIZE);
	if (HMAC_BLOCK_SIZE < key_len) {
		git_SHA1_Init(&ctx);
		git_SHA1_Update(&ctx, key_in, key_len);
		git_SHA1_Final(key, &ctx);
	} else {
		memcpy(key, key_in, key_len);
	}
 
	/* RFC 2104 2. (2) & (5) */
	for (i = 0; i < sizeof(key); i++) {
		k_ipad[i] = key[i] ^ 0x36;
		k_opad[i] = key[i] ^ 0x5c;
	}
 
	/* RFC 2104 2. (3) & (4) */
	git_SHA1_Init(&ctx);
	git_SHA1_Update(&ctx, k_ipad, sizeof(k_ipad));
	git_SHA1_Update(&ctx, text, text_len);
	git_SHA1_Final(out, &ctx);
 
	/* RFC 2104 2. (6) & (7) */
	git_SHA1_Init(&ctx);
	git_SHA1_Update(&ctx, k_opad, sizeof(k_opad));
	git_SHA1_Update(&ctx, out, 20);
	git_SHA1_Final(out, &ctx);
}
 
static char *prepare_push_cert_nonce(const char *path, unsigned long stamp)
{
	struct strbuf buf = STRBUF_INIT;
	unsigned char sha1[20];
 
	strbuf_addf(&buf, "%s:%lu", path, stamp);
	hmac_sha1(sha1, buf.buf, buf.len, cert_nonce_seed, strlen(cert_nonce_seed));;
	strbuf_release(&buf);
 
	/* RFC 2104 5. HMAC-SHA1-80 */
	strbuf_addf(&buf, "%lu-%.*s", stamp, 20, sha1_to_hex(sha1));
	return strbuf_detach(&buf, NULL);
}
 
/*
 * NEEDSWORK: reuse find_commit_header() from jk/commit-author-parsing
 * after dropping "_commit" from its name and possibly moving it out
 * of commit.c
 */
static char *find_header(const char *msg, size_t len, const char *key)
{
	int key_len = strlen(key);
	const char *line = msg;
 
	while (line && line < msg + len) {
		const char *eol = strchrnul(line, '\n');
 
		if ((msg + len <= eol) || line == eol)
			return NULL;
		if (line + key_len < eol &&
		    !memcmp(line, key, key_len) && line[key_len] == ' ') {
			int offset = key_len + 1;
			return xmemdupz(line + offset, (eol - line) - offset);
		}
		line = *eol ? eol + 1 : NULL;
	}
	return NULL;
}
 
static const char *check_nonce(const char *buf, size_t len)
{
	char *nonce = find_header(buf, len, "nonce");
	unsigned long stamp, ostamp;
	char *bohmac, *expect = NULL;
	const char *retval = NONCE_BAD;
 
	if (!nonce) {
		retval = NONCE_MISSING;
		goto leave;
	} else if (!push_cert_nonce) {
		retval = NONCE_UNSOLICITED;
		goto leave;
	} else if (!strcmp(push_cert_nonce, nonce)) {
		retval = NONCE_OK;
		goto leave;
	}
 
	if (!stateless_rpc) {
		/* returned nonce MUST match what we gave out earlier */
		retval = NONCE_BAD;
		goto leave;
	}
 
	/*
	 * In stateless mode, we may be receiving a nonce issued by
	 * another instance of the server that serving the same
	 * repository, and the timestamps may not match, but the
	 * nonce-seed and dir should match, so we can recompute and
	 * report the time slop.
	 *
	 * In addition, when a nonce issued by another instance has
	 * timestamp within receive.certnonceslop seconds, we pretend
	 * as if we issued that nonce when reporting to the hook.
	 */
 
	/* nonce is concat(<seconds-since-epoch>, "-", <hmac>) */
	if (*nonce <= '0' || '9' < *nonce) {
		retval = NONCE_BAD;
		goto leave;
	}
	stamp = strtoul(nonce, &bohmac, 10);
	if (bohmac == nonce || bohmac[0] != '-') {
		retval = NONCE_BAD;
		goto leave;
	}
 
	expect = prepare_push_cert_nonce(service_dir, stamp);
	if (strcmp(expect, nonce)) {
		/* Not what we would have signed earlier */
		retval = NONCE_BAD;
		goto leave;
	}
 
	/*
	 * By how many seconds is this nonce stale?  Negative value
	 * would mean it was issued by another server with its clock
	 * skewed in the future.
	 */
	ostamp = strtoul(push_cert_nonce, NULL, 10);
	nonce_stamp_slop = (long)ostamp - (long)stamp;
 
	if (nonce_stamp_slop_limit &&
	    abs(nonce_stamp_slop) <= nonce_stamp_slop_limit) {
		/*
		 * Pretend as if the received nonce (which passes the
		 * HMAC check, so it is not a forged by third-party)
		 * is what we issued.
		 */
		free((void *)push_cert_nonce);
		push_cert_nonce = xstrdup(nonce);
		retval = NONCE_OK;
	} else {
		retval = NONCE_SLOP;
	}
 
leave:
	free(nonce);
	free(expect);
	return retval;
}
 
static void prepare_push_cert_sha1(struct child_process *proc)
{
	static int already_done;
	struct argv_array env = ARGV_ARRAY_INIT;
 
	if (!push_cert.len)
		return;
 
	if (!already_done) {
		struct strbuf gpg_output = STRBUF_INIT;
		struct strbuf gpg_status = STRBUF_INIT;
		int bogs /* beginning_of_gpg_sig */;
 
		already_done = 1;
		if (write_sha1_file(push_cert.buf, push_cert.len, "blob", push_cert_sha1))
			hashclr(push_cert_sha1);
 
		memset(&sigcheck, '\0', sizeof(sigcheck));
		sigcheck.result = 'N';
 
		bogs = parse_signature(push_cert.buf, push_cert.len);
		if (verify_signed_buffer(push_cert.buf, bogs,
					 push_cert.buf + bogs, push_cert.len - bogs,
					 &gpg_output, &gpg_status) < 0) {
			; /* error running gpg */
		} else {
			sigcheck.payload = push_cert.buf;
			sigcheck.gpg_output = gpg_output.buf;
			sigcheck.gpg_status = gpg_status.buf;
			parse_gpg_output(&sigcheck);
		}
 
		strbuf_release(&gpg_output);
		strbuf_release(&gpg_status);
		nonce_status = check_nonce(push_cert.buf, bogs);
	}
	if (!is_null_sha1(push_cert_sha1)) {
		argv_array_pushf(&env, "GIT_PUSH_CERT=%s", sha1_to_hex(push_cert_sha1));
		argv_array_pushf(&env, "GIT_PUSH_CERT_SIGNER=%s",
				 sigcheck.signer ? sigcheck.signer : "");
		argv_array_pushf(&env, "GIT_PUSH_CERT_KEY=%s",
				 sigcheck.key ? sigcheck.key : "");
		argv_array_pushf(&env, "GIT_PUSH_CERT_STATUS=%c", sigcheck.result);
		if (push_cert_nonce) {
			argv_array_pushf(&env, "GIT_PUSH_CERT_NONCE=%s", push_cert_nonce);
			argv_array_pushf(&env, "GIT_PUSH_CERT_NONCE_STATUS=%s", nonce_status);
			if (nonce_status == NONCE_SLOP)
				argv_array_pushf(&env, "GIT_PUSH_CERT_NONCE_SLOP=%ld",
						 nonce_stamp_slop);
		}
		proc->env = env.argv;
	}
}
 
typedef int (*feed_fn)(void *, const char **, size_t *);
static int run_and_feed_hook(const char *hook_name, feed_fn feed, void *feed_state)
{
	struct child_process proc = CHILD_PROCESS_INIT;
	struct async muxer;
	const char *argv[2];
	int code;
 
	argv[0] = find_hook(hook_name);
	if (!argv[0])
		return 0;
 
	argv[1] = NULL;
 
	proc.argv = argv;
	proc.in = -1;
	proc.stdout_to_stderr = 1;
 
	prepare_push_cert_sha1(&proc);
 
	if (use_sideband) {
		memset(&muxer, 0, sizeof(muxer));
		muxer.proc = copy_to_sideband;
		muxer.in = -1;
		code = start_async(&muxer);
		if (code)
			return code;
		proc.err = muxer.in;
	}
 
	code = start_command(&proc);
	if (code) {
		if (use_sideband)
			finish_async(&muxer);
		return code;
	}
 
	sigchain_push(SIGPIPE, SIG_IGN);
 
	while (1) {
		const char *buf;
		size_t n;
		if (feed(feed_state, &buf, &n))
			break;
		if (write_in_full(proc.in, buf, n) != n)
			break;
	}
	close(proc.in);
	if (use_sideband)
		finish_async(&muxer);
 
	sigchain_pop(SIGPIPE);
 
	return finish_command(&proc);
}
 
struct receive_hook_feed_state {
	struct command *cmd;
	int skip_broken;
	struct strbuf buf;
};
 
static int feed_receive_hook(void *state_, const char **bufp, size_t *sizep)
{
	struct receive_hook_feed_state *state = state_;
	struct command *cmd = state->cmd;
 
	while (cmd &&
	       state->skip_broken && (cmd->error_string || cmd->did_not_exist))
		cmd = cmd->next;
	if (!cmd)
		return -1; /* EOF */
	strbuf_reset(&state->buf);
	strbuf_addf(&state->buf, "%s %s %s\n",
		    sha1_to_hex(cmd->old_sha1), sha1_to_hex(cmd->new_sha1),
		    cmd->ref_name);
	state->cmd = cmd->next;
	if (bufp) {
		*bufp = state->buf.buf;
		*sizep = state->buf.len;
	}
	return 0;
}
 
static int run_receive_hook(struct command *commands, const char *hook_name,
			    int skip_broken)
{
	struct receive_hook_feed_state state;
	int status;
 
	strbuf_init(&state.buf, 0);
	state.cmd = commands;
	state.skip_broken = skip_broken;
	if (feed_receive_hook(&state, NULL, NULL))
		return 0;
	state.cmd = commands;
	status = run_and_feed_hook(hook_name, feed_receive_hook, &state);
	strbuf_release(&state.buf);
	return status;
}
 
static int run_update_hook(struct command *cmd)
{
	const char *argv[5];
	struct child_process proc = CHILD_PROCESS_INIT;
	int code;
 
	argv[0] = find_hook("update");
	if (!argv[0])
		return 0;
 
	argv[1] = cmd->ref_name;
	argv[2] = sha1_to_hex(cmd->old_sha1);
	argv[3] = sha1_to_hex(cmd->new_sha1);
	argv[4] = NULL;
 
	proc.no_stdin = 1;
	proc.stdout_to_stderr = 1;
	proc.err = use_sideband ? -1 : 0;
	proc.argv = argv;
 
	code = start_command(&proc);
	if (code)
		return code;
	if (use_sideband)
		copy_to_sideband(proc.err, -1, NULL);
	return finish_command(&proc);
}
 
static int is_ref_checked_out(const char *ref)
{
	if (is_bare_repository())
		return 0;
 
	if (!head_name)
		return 0;
	return !strcmp(head_name, ref);
}
 
static char *refuse_unconfigured_deny_msg[] = {
	"By default, updating the current branch in a non-bare repository",
	"is denied, because it will make the index and work tree inconsistent",
	"with what you pushed, and will require 'git reset --hard' to match",
	"the work tree to HEAD.",
	"",
	"You can set 'receive.denyCurrentBranch' configuration variable to",
	"'ignore' or 'warn' in the remote repository to allow pushing into",
	"its current branch; however, this is not recommended unless you",
	"arranged to update its work tree to match what you pushed in some",
	"other way.",
	"",
	"To squelch this message and still keep the default behaviour, set",
	"'receive.denyCurrentBranch' configuration variable to 'refuse'."
};
 
static void refuse_unconfigured_deny(void)
{
	int i;
	for (i = 0; i < ARRAY_SIZE(refuse_unconfigured_deny_msg); i++)
		rp_error("%s", refuse_unconfigured_deny_msg[i]);
}
 
static char *refuse_unconfigured_deny_delete_current_msg[] = {
	"By default, deleting the current branch is denied, because the next",
	"'git clone' won't result in any file checked out, causing confusion.",
	"",
	"You can set 'receive.denyDeleteCurrent' configuration variable to",
	"'warn' or 'ignore' in the remote repository to allow deleting the",
	"current branch, with or without a warning message.",
	"",
	"To squelch this message, you can set it to 'refuse'."
};
 
static void refuse_unconfigured_deny_delete_current(void)
{
	int i;
	for (i = 0;
	     i < ARRAY_SIZE(refuse_unconfigured_deny_delete_current_msg);
	     i++)
		rp_error("%s", refuse_unconfigured_deny_delete_current_msg[i]);
}
 
static int command_singleton_iterator(void *cb_data, unsigned char sha1[20]);
static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
{
	static struct lock_file shallow_lock;
	struct sha1_array extra = SHA1_ARRAY_INIT;
	const char *alt_file;
	uint32_t mask = 1 << (cmd->index % 32);
	int i;
 
	trace_printf_key(&trace_shallow,
			 "shallow: update_shallow_ref %s\n", cmd->ref_name);
	for (i = 0; i < si->shallow->nr; i++)
		if (si->used_shallow[i] &&
		    (si->used_shallow[i][cmd->index / 32] & mask) &&
		    !delayed_reachability_test(si, i))
			sha1_array_append(&extra, si->shallow->sha1[i]);
 
	setup_alternate_shallow(&shallow_lock, &alt_file, &extra);
	if (check_shallow_connected(command_singleton_iterator,
				    0, cmd, alt_file)) {
		rollback_lock_file(&shallow_lock);
		sha1_array_clear(&extra);
		return -1;
	}
 
	commit_lock_file(&shallow_lock);
 
	/*
	 * Make sure setup_alternate_shallow() for the next ref does
	 * not lose these new roots..
	 */
	for (i = 0; i < extra.nr; i++)
		register_shallow(extra.sha1[i]);
 
	si->shallow_ref[cmd->index] = 0;
	sha1_array_clear(&extra);
	return 0;
}
 
static const char *update(struct command *cmd, struct shallow_info *si)
{
	const char *name = cmd->ref_name;
	struct strbuf namespaced_name_buf = STRBUF_INIT;
	const char *namespaced_name;
	unsigned char *old_sha1 = cmd->old_sha1;
	unsigned char *new_sha1 = cmd->new_sha1;
 
	/* only refs/... are allowed */
	if (!starts_with(name, "refs/") || check_refname_format(name + 5, 0)) {
		rp_error("refusing to create funny ref '%s' remotely", name);
		return "funny refname";
	}
 
	strbuf_addf(&namespaced_name_buf, "%s%s", get_git_namespace(), name);
	namespaced_name = strbuf_detach(&namespaced_name_buf, NULL);
 
	if (is_ref_checked_out(namespaced_name)) {
		switch (deny_current_branch) {
		case DENY_IGNORE:
			break;
		case DENY_WARN:
			rp_warning("updating the current branch");
			break;
		case DENY_REFUSE:
		case DENY_UNCONFIGURED:
			rp_error("refusing to update checked out branch: %s", name);
			if (deny_current_branch == DENY_UNCONFIGURED)
				refuse_unconfigured_deny();
			return "branch is currently checked out";
		}
	}
 
	if (!is_null_sha1(new_sha1) && !has_sha1_file(new_sha1)) {
		error("unpack should have generated %s, "
		      "but I can't find it!", sha1_to_hex(new_sha1));
		return "bad pack";
	}
 
	if (!is_null_sha1(old_sha1) && is_null_sha1(new_sha1)) {
		if (deny_deletes && starts_with(name, "refs/heads/")) {
			rp_error("denying ref deletion for %s", name);
			return "deletion prohibited";
		}
 
		if (!strcmp(namespaced_name, head_name)) {
			switch (deny_delete_current) {
			case DENY_IGNORE:
				break;
			case DENY_WARN:
				rp_warning("deleting the current branch");
				break;
			case DENY_REFUSE:
			case DENY_UNCONFIGURED:
				if (deny_delete_current == DENY_UNCONFIGURED)
					refuse_unconfigured_deny_delete_current();
				rp_error("refusing to delete the current branch: %s", name);
				return "deletion of the current branch prohibited";
			}
		}
	}
 
	if (deny_non_fast_forwards && !is_null_sha1(new_sha1) &&
	    !is_null_sha1(old_sha1) &&
	    starts_with(name, "refs/heads/")) {
		struct object *old_object, *new_object;
		struct commit *old_commit, *new_commit;
 
		old_object = parse_object(old_sha1);
		new_object = parse_object(new_sha1);
 
		if (!old_object || !new_object ||
		    old_object->type != OBJ_COMMIT ||
		    new_object->type != OBJ_COMMIT) {
			error("bad sha1 objects for %s", name);
			return "bad ref";
		}
		old_commit = (struct commit *)old_object;
		new_commit = (struct commit *)new_object;
		if (!in_merge_bases(old_commit, new_commit)) {
			rp_error("denying non-fast-forward %s"
				 " (you should pull first)", name);
			return "non-fast-forward";
		}
	}
	if (run_update_hook(cmd)) {
		rp_error("hook declined to update %s", name);
		return "hook declined";
	}
 
	if (is_null_sha1(new_sha1)) {
		if (!parse_object(old_sha1)) {
			old_sha1 = NULL;
			if (ref_exists(name)) {
				rp_warning("Allowing deletion of corrupt ref.");
			} else {
				rp_warning("Deleting a non-existent ref.");
				cmd->did_not_exist = 1;
			}
		}
		if (delete_ref(namespaced_name, old_sha1, 0)) {
			rp_error("failed to delete %s", name);
			return "failed to delete";
		}
		return NULL; /* good */
	}
	else {
		struct strbuf err = STRBUF_INIT;
		struct ref_transaction *transaction;
 
		if (shallow_update && si->shallow_ref[cmd->index] &&
		    update_shallow_ref(cmd, si))
			return "shallow error";
 
		transaction = ref_transaction_begin(&err);
		if (!transaction ||
		    ref_transaction_update(transaction, namespaced_name,
					   new_sha1, old_sha1, 0, 1, &err) ||
		    ref_transaction_commit(transaction, "push", &err)) {
			ref_transaction_free(transaction);
 
			rp_error("%s", err.buf);
			strbuf_release(&err);
			return "failed to update ref";
		}
 
		ref_transaction_free(transaction);
		strbuf_release(&err);
		return NULL; /* good */
	}
}
 
static void run_update_post_hook(struct command *commands)
{
	struct command *cmd;
	int argc;
	const char **argv;
	struct child_process proc = CHILD_PROCESS_INIT;
	char *hook;
 
	hook = find_hook("post-update");
	for (argc = 0, cmd = commands; cmd; cmd = cmd->next) {
		if (cmd->error_string || cmd->did_not_exist)
			continue;
		argc++;
	}
	if (!argc || !hook)
		return;
 
	argv = xmalloc(sizeof(*argv) * (2 + argc));
	argv[0] = hook;
 
	for (argc = 1, cmd = commands; cmd; cmd = cmd->next) {
		if (cmd->error_string || cmd->did_not_exist)
			continue;
		argv[argc] = xstrdup(cmd->ref_name);
		argc++;
	}
	argv[argc] = NULL;
 
	proc.no_stdin = 1;
	proc.stdout_to_stderr = 1;
	proc.err = use_sideband ? -1 : 0;
	proc.argv = argv;
 
	if (!start_command(&proc)) {
		if (use_sideband)
			copy_to_sideband(proc.err, -1, NULL);
		finish_command(&proc);
	}
}
 
static void check_aliased_update(struct command *cmd, struct string_list *list)
{
	struct strbuf buf = STRBUF_INIT;
	const char *dst_name;
	struct string_list_item *item;
	struct command *dst_cmd;
	unsigned char sha1[20];
	char cmd_oldh[41], cmd_newh[41], dst_oldh[41], dst_newh[41];
	int flag;
 
	strbuf_addf(&buf, "%s%s", get_git_namespace(), cmd->ref_name);
	dst_name = resolve_ref_unsafe(buf.buf, sha1, 0, &flag);
	strbuf_release(&buf);
 
	if (!(flag & REF_ISSYMREF))
		return;
 
	dst_name = strip_namespace(dst_name);
	if (!dst_name) {
		rp_error("refusing update to broken symref '%s'", cmd->ref_name);
		cmd->skip_update = 1;
		cmd->error_string = "broken symref";
		return;
	}
 
	if ((item = string_list_lookup(list, dst_name)) == NULL)
		return;
 
	cmd->skip_update = 1;
 
	dst_cmd = (struct command *) item->util;
 
	if (!hashcmp(cmd->old_sha1, dst_cmd->old_sha1) &&
	    !hashcmp(cmd->new_sha1, dst_cmd->new_sha1))
		return;
 
	dst_cmd->skip_update = 1;
 
	strcpy(cmd_oldh, find_unique_abbrev(cmd->old_sha1, DEFAULT_ABBREV));
	strcpy(cmd_newh, find_unique_abbrev(cmd->new_sha1, DEFAULT_ABBREV));
	strcpy(dst_oldh, find_unique_abbrev(dst_cmd->old_sha1, DEFAULT_ABBREV));
	strcpy(dst_newh, find_unique_abbrev(dst_cmd->new_sha1, DEFAULT_ABBREV));
	rp_error("refusing inconsistent update between symref '%s' (%s..%s) and"
		 " its target '%s' (%s..%s)",
		 cmd->ref_name, cmd_oldh, cmd_newh,
		 dst_cmd->ref_name, dst_oldh, dst_newh);
 
	cmd->error_string = dst_cmd->error_string =
		"inconsistent aliased update";
}
 
static void check_aliased_updates(struct command *commands)
{
	struct command *cmd;
	struct string_list ref_list = STRING_LIST_INIT_NODUP;
 
	for (cmd = commands; cmd; cmd = cmd->next) {
		struct string_list_item *item =
			string_list_append(&ref_list, cmd->ref_name);
		item->util = (void *)cmd;
	}
	sort_string_list(&ref_list);
 
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (!cmd->error_string)
			check_aliased_update(cmd, &ref_list);
	}
 
	string_list_clear(&ref_list, 0);
}
 
static int command_singleton_iterator(void *cb_data, unsigned char sha1[20])
{
	struct command **cmd_list = cb_data;
	struct command *cmd = *cmd_list;
 
	if (!cmd || is_null_sha1(cmd->new_sha1))
		return -1; /* end of list */
	*cmd_list = NULL; /* this returns only one */
	hashcpy(sha1, cmd->new_sha1);
	return 0;
}
 
static void set_connectivity_errors(struct command *commands,
				    struct shallow_info *si)
{
	struct command *cmd;
 
	for (cmd = commands; cmd; cmd = cmd->next) {
		struct command *singleton = cmd;
		if (shallow_update && si->shallow_ref[cmd->index])
			/* to be checked in update_shallow_ref() */
			continue;
		if (!check_everything_connected(command_singleton_iterator,
						0, &singleton))
			continue;
		cmd->error_string = "missing necessary objects";
	}
}
 
struct iterate_data {
	struct command *cmds;
	struct shallow_info *si;
};
 
static int iterate_receive_command_list(void *cb_data, unsigned char sha1[20])
{
	struct iterate_data *data = cb_data;
	struct command **cmd_list = &data->cmds;
	struct command *cmd = *cmd_list;
 
	for (; cmd; cmd = cmd->next) {
		if (shallow_update && data->si->shallow_ref[cmd->index])
			/* to be checked in update_shallow_ref() */
			continue;
		if (!is_null_sha1(cmd->new_sha1) && !cmd->skip_update) {
			hashcpy(sha1, cmd->new_sha1);
			*cmd_list = cmd->next;
			return 0;
		}
	}
	*cmd_list = NULL;
	return -1; /* end of list */
}
 
static void reject_updates_to_hidden(struct command *commands)
{
	struct command *cmd;
 
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (cmd->error_string || !ref_is_hidden(cmd->ref_name))
			continue;
		if (is_null_sha1(cmd->new_sha1))
			cmd->error_string = "deny deleting a hidden ref";
		else
			cmd->error_string = "deny updating a hidden ref";
	}
}
 
static void execute_commands(struct command *commands,
			     const char *unpacker_error,
			     struct shallow_info *si)
{
	int checked_connectivity;
	struct command *cmd;
	unsigned char sha1[20];
	struct iterate_data data;
 
	if (unpacker_error) {
		for (cmd = commands; cmd; cmd = cmd->next)
			cmd->error_string = "unpacker error";
		return;
	}
 
	data.cmds = commands;
	data.si = si;
	if (check_everything_connected(iterate_receive_command_list, 0, &data))
		set_connectivity_errors(commands, si);
 
	reject_updates_to_hidden(commands);
 
	if (run_receive_hook(commands, "pre-receive", 0)) {
		for (cmd = commands; cmd; cmd = cmd->next) {
			if (!cmd->error_string)
				cmd->error_string = "pre-receive hook declined";
		}
		return;
	}
 
	check_aliased_updates(commands);
 
	free(head_name_to_free);
	head_name = head_name_to_free = resolve_refdup("HEAD", sha1, 0, NULL);
 
	checked_connectivity = 1;
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (cmd->error_string)
			continue;
 
		if (cmd->skip_update)
			continue;
 
		cmd->error_string = update(cmd, si);
		if (shallow_update && !cmd->error_string &&
		    si->shallow_ref[cmd->index]) {
			error("BUG: connectivity check has not been run on ref %s",
			      cmd->ref_name);
			checked_connectivity = 0;
		}
	}
 
	if (shallow_update && !checked_connectivity)
		error("BUG: run 'git fsck' for safety.\n"
		      "If there are errors, try to remove "
		      "the reported refs above");
}
 
static struct command **queue_command(struct command **tail,
				      const char *line,
				      int linelen)
{
	unsigned char old_sha1[20], new_sha1[20];
	struct command *cmd;
	const char *refname;
	int reflen;
 
	if (linelen < 83 ||
	    line[40] != ' ' ||
	    line[81] != ' ' ||
	    get_sha1_hex(line, old_sha1) ||
	    get_sha1_hex(line + 41, new_sha1))
		die("protocol error: expected old/new/ref, got '%s'", line);
 
	refname = line + 82;
	reflen = linelen - 82;
	cmd = xcalloc(1, sizeof(struct command) + reflen + 1);
	hashcpy(cmd->old_sha1, old_sha1);
	hashcpy(cmd->new_sha1, new_sha1);
	memcpy(cmd->ref_name, refname, reflen);
	cmd->ref_name[reflen] = '\0';
	*tail = cmd;
	return &cmd->next;
}
 
static void queue_commands_from_cert(struct command **tail,
				     struct strbuf *push_cert)
{
	const char *boc, *eoc;
 
	if (*tail)
		die("protocol error: got both push certificate and unsigned commands");
 
	boc = strstr(push_cert->buf, "\n\n");
	if (!boc)
		die("malformed push certificate %.*s", 100, push_cert->buf);
	else
		boc += 2;
	eoc = push_cert->buf + parse_signature(push_cert->buf, push_cert->len);
 
	while (boc < eoc) {
		const char *eol = memchr(boc, '\n', eoc - boc);
		tail = queue_command(tail, boc, eol ? eol - boc : eoc - eol);
		boc = eol ? eol + 1 : eoc;
	}
}
 
static struct command *read_head_info(struct sha1_array *shallow)
{
	struct command *commands = NULL;
	struct command **p = &commands;
	for (;;) {
		char *line;
		int len, linelen;
 
		line = packet_read_line(0, &len);
		if (!line)
			break;
 
		if (len == 48 && starts_with(line, "shallow ")) {
			unsigned char sha1[20];
			if (get_sha1_hex(line + 8, sha1))
				die("protocol error: expected shallow sha, got '%s'",
				    line + 8);
			sha1_array_append(shallow, sha1);
			continue;
		}
 
		linelen = strlen(line);
		if (linelen < len) {
			const char *feature_list = line + linelen + 1;
			if (parse_feature_request(feature_list, "report-status"))
				report_status = 1;
			if (parse_feature_request(feature_list, "side-band-64k"))
				use_sideband = LARGE_PACKET_MAX;
			if (parse_feature_request(feature_list, "quiet"))
				quiet = 1;
		}
 
		if (!strcmp(line, "push-cert")) {
			int true_flush = 0;
			char certbuf[1024];
 
			for (;;) {
				len = packet_read(0, NULL, NULL,
						  certbuf, sizeof(certbuf), 0);
				if (!len) {
					true_flush = 1;
					break;
				}
				if (!strcmp(certbuf, "push-cert-end\n"))
					break; /* end of cert */
				strbuf_addstr(&push_cert, certbuf);
			}
 
			if (true_flush)
				break;
			continue;
		}
 
		p = queue_command(p, line, linelen);
	}
 
	if (push_cert.len)
		queue_commands_from_cert(p, &push_cert);
 
	return commands;
}
 
static const char *parse_pack_header(struct pack_header *hdr)
{
	switch (read_pack_header(0, hdr)) {
	case PH_ERROR_EOF:
		return "eof before pack header was fully read";
 
	case PH_ERROR_PACK_SIGNATURE:
		return "protocol error (pack signature mismatch detected)";
 
	case PH_ERROR_PROTOCOL:
		return "protocol error (pack version unsupported)";
 
	default:
		return "unknown error in parse_pack_header";
 
	case 0:
		return NULL;
	}
}
 
static const char *pack_lockfile;
 
static const char *unpack(int err_fd, struct shallow_info *si)
{
	struct pack_header hdr;
	const char *hdr_err;
	int status;
	char hdr_arg[38];
	struct child_process child = CHILD_PROCESS_INIT;
	int fsck_objects = (receive_fsck_objects >= 0
			    ? receive_fsck_objects
			    : transfer_fsck_objects >= 0
			    ? transfer_fsck_objects
			    : 0);
 
	hdr_err = parse_pack_header(&hdr);
	if (hdr_err) {
		if (err_fd > 0)
			close(err_fd);
		return hdr_err;
	}
	snprintf(hdr_arg, sizeof(hdr_arg),
			"--pack_header=%"PRIu32",%"PRIu32,
			ntohl(hdr.hdr_version), ntohl(hdr.hdr_entries));
 
	if (si->nr_ours || si->nr_theirs) {
		alt_shallow_file = setup_temporary_shallow(si->shallow);
		argv_array_push(&child.args, "--shallow-file");
		argv_array_push(&child.args, alt_shallow_file);
	}
 
	if (ntohl(hdr.hdr_entries) < unpack_limit) {
		argv_array_pushl(&child.args, "unpack-objects", hdr_arg, NULL);
		if (quiet)
			argv_array_push(&child.args, "-q");
		if (fsck_objects)
			argv_array_push(&child.args, "--strict");
		child.no_stdout = 1;
		child.err = err_fd;
		child.git_cmd = 1;
		status = run_command(&child);
		if (status)
			return "unpack-objects abnormal exit";
	} else {
		int s;
		char keep_arg[256];
 
		s = sprintf(keep_arg, "--keep=receive-pack %"PRIuMAX" on ", (uintmax_t) getpid());
		if (gethostname(keep_arg + s, sizeof(keep_arg) - s))
			strcpy(keep_arg + s, "localhost");
 
		argv_array_pushl(&child.args, "index-pack",
				 "--stdin", hdr_arg, keep_arg, NULL);
		if (fsck_objects)
			argv_array_push(&child.args, "--strict");
		if (fix_thin)
			argv_array_push(&child.args, "--fix-thin");
		child.out = -1;
		child.err = err_fd;
		child.git_cmd = 1;
		status = start_command(&child);
		if (status)
			return "index-pack fork failed";
		pack_lockfile = index_pack_lockfile(child.out);
		close(child.out);
		status = finish_command(&child);
		if (status)
			return "index-pack abnormal exit";
		reprepare_packed_git();
	}
	return NULL;
}
 
static const char *unpack_with_sideband(struct shallow_info *si)
{
	struct async muxer;
	const char *ret;
 
	if (!use_sideband)
		return unpack(0, si);
 
	memset(&muxer, 0, sizeof(muxer));
	muxer.proc = copy_to_sideband;
	muxer.in = -1;
	if (start_async(&muxer))
		return NULL;
 
	ret = unpack(muxer.in, si);
 
	finish_async(&muxer);
	return ret;
}
 
static void prepare_shallow_update(struct command *commands,
				   struct shallow_info *si)
{
	int i, j, k, bitmap_size = (si->ref->nr + 31) / 32;
 
	si->used_shallow = xmalloc(sizeof(*si->used_shallow) *
				   si->shallow->nr);
	assign_shallow_commits_to_refs(si, si->used_shallow, NULL);
 
	si->need_reachability_test =
		xcalloc(si->shallow->nr, sizeof(*si->need_reachability_test));
	si->reachable =
		xcalloc(si->shallow->nr, sizeof(*si->reachable));
	si->shallow_ref = xcalloc(si->ref->nr, sizeof(*si->shallow_ref));
 
	for (i = 0; i < si->nr_ours; i++)
		si->need_reachability_test[si->ours[i]] = 1;
 
	for (i = 0; i < si->shallow->nr; i++) {
		if (!si->used_shallow[i])
			continue;
		for (j = 0; j < bitmap_size; j++) {
			if (!si->used_shallow[i][j])
				continue;
			si->need_reachability_test[i]++;
			for (k = 0; k < 32; k++)
				if (si->used_shallow[i][j] & (1 << k))
					si->shallow_ref[j * 32 + k]++;
		}
 
		/*
		 * true for those associated with some refs and belong
		 * in "ours" list aka "step 7 not done yet"
		 */
		si->need_reachability_test[i] =
			si->need_reachability_test[i] > 1;
	}
 
	/*
	 * keep hooks happy by forcing a temporary shallow file via
	 * env variable because we can't add --shallow-file to every
	 * command. check_everything_connected() will be done with
	 * true .git/shallow though.
	 */
	setenv(GIT_SHALLOW_FILE_ENVIRONMENT, alt_shallow_file, 1);
}
 
static void update_shallow_info(struct command *commands,
				struct shallow_info *si,
				struct sha1_array *ref)
{
	struct command *cmd;
	int *ref_status;
	remove_nonexistent_theirs_shallow(si);
	if (!si->nr_ours && !si->nr_theirs) {
		shallow_update = 0;
		return;
	}
 
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (is_null_sha1(cmd->new_sha1))
			continue;
		sha1_array_append(ref, cmd->new_sha1);
		cmd->index = ref->nr - 1;
	}
	si->ref = ref;
 
	if (shallow_update) {
		prepare_shallow_update(commands, si);
		return;
	}
 
	ref_status = xmalloc(sizeof(*ref_status) * ref->nr);
	assign_shallow_commits_to_refs(si, NULL, ref_status);
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (is_null_sha1(cmd->new_sha1))
			continue;
		if (ref_status[cmd->index]) {
			cmd->error_string = "shallow update not allowed";
			cmd->skip_update = 1;
		}
	}
	free(ref_status);
}
 
static void report(struct command *commands, const char *unpack_status)
{
	struct command *cmd;
	struct strbuf buf = STRBUF_INIT;
 
	packet_buf_write(&buf, "unpack %s\n",
			 unpack_status ? unpack_status : "ok");
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (!cmd->error_string)
			packet_buf_write(&buf, "ok %s\n",
					 cmd->ref_name);
		else
			packet_buf_write(&buf, "ng %s %s\n",
					 cmd->ref_name, cmd->error_string);
	}
	packet_buf_flush(&buf);
 
	if (use_sideband)
		send_sideband(1, 1, buf.buf, buf.len, use_sideband);
	else
		write_or_die(1, buf.buf, buf.len);
	strbuf_release(&buf);
}
 
static int delete_only(struct command *commands)
{
	struct command *cmd;
	for (cmd = commands; cmd; cmd = cmd->next) {
		if (!is_null_sha1(cmd->new_sha1))
			return 0;
	}
	return 1;
}
 
int cmd_receive_pack(int argc, const char **argv, const char *prefix)
{
	int advertise_refs = 0;
	int i;
	struct command *commands;
	struct sha1_array shallow = SHA1_ARRAY_INIT;
	struct sha1_array ref = SHA1_ARRAY_INIT;
	struct shallow_info si;
 
	packet_trace_identity("receive-pack");
 
	argv++;
	for (i = 1; i < argc; i++) {
		const char *arg = *argv++;
 
		if (*arg == '-') {
			if (!strcmp(arg, "--quiet")) {
				quiet = 1;
				continue;
			}
 
			if (!strcmp(arg, "--advertise-refs")) {
				advertise_refs = 1;
				continue;
			}
			if (!strcmp(arg, "--stateless-rpc")) {
				stateless_rpc = 1;
				continue;
			}
			if (!strcmp(arg, "--reject-thin-pack-for-testing")) {
				fix_thin = 0;
				continue;
			}
 
			usage(receive_pack_usage);
		}
		if (service_dir)
			usage(receive_pack_usage);
		service_dir = arg;
	}
	if (!service_dir)
		usage(receive_pack_usage);
 
	setup_path();
 
	if (!enter_repo(service_dir, 0))
		die("'%s' does not appear to be a git repository", service_dir);
 
	git_config(receive_pack_config, NULL);
	if (cert_nonce_seed)
		push_cert_nonce = prepare_push_cert_nonce(service_dir, time(NULL));
 
	if (0 <= transfer_unpack_limit)
		unpack_limit = transfer_unpack_limit;
	else if (0 <= receive_unpack_limit)
		unpack_limit = receive_unpack_limit;
 
	if (advertise_refs || !stateless_rpc) {
		write_head_info();
	}
	if (advertise_refs)
		return 0;
 
	if ((commands = read_head_info(&shallow)) != NULL) {
		const char *unpack_status = NULL;
 
		prepare_shallow_info(&si, &shallow);
		if (!si.nr_ours && !si.nr_theirs)
			shallow_update = 0;
		if (!delete_only(commands)) {
			unpack_status = unpack_with_sideband(&si);
			update_shallow_info(commands, &si, &ref);
		}
		execute_commands(commands, unpack_status, &si);
		if (pack_lockfile)
			unlink_or_warn(pack_lockfile);
		if (report_status)
			report(commands, unpack_status);
		run_receive_hook(commands, "post-receive", 1);
		run_update_post_hook(commands);
		if (auto_gc) {
			const char *argv_gc_auto[] = {
				"gc", "--auto", "--quiet", NULL,
			};
			int opt = RUN_GIT_CMD | RUN_COMMAND_STDOUT_TO_STDERR;
			run_command_v_opt(argv_gc_auto, opt);
		}
		if (auto_update_server_info)
			update_server_info(0);
		clear_shallow_info(&si);
	}
	if (use_sideband)
		packet_flush(1);
	sha1_array_clear(&shallow);
	sha1_array_clear(&ref);
	free((void *)push_cert_nonce);
	return 0;
}