about summary refs log blame commit diff
path: root/builtin/index-pack.c
blob: 0d55f73b0b443b60dccc31096675d40691b3eb56 (plain) (tree)
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
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                                                                                         
#include "builtin.h"
#include "config.h"
#include "delta.h"
#include "pack.h"
#include "csum-file.h"
#include "blob.h"
#include "commit.h"
#include "tag.h"
#include "tree.h"
#include "progress.h"
#include "fsck.h"
#include "exec-cmd.h"
#include "streaming.h"
#include "thread-utils.h"
#include "packfile.h"
#include "object-store.h"
#include "fetch-object.h"

static const char index_pack_usage[] =
"git index-pack [-v] [-o <index-file>] [--keep | --keep=<msg>] [--verify] [--strict] (<pack-file> | --stdin [--fix-thin] [<pack-file>])";

struct object_entry {
	struct pack_idx_entry idx;
	unsigned long size;
	unsigned char hdr_size;
	signed char type;
	signed char real_type;
};

struct object_stat {
	unsigned delta_depth;
	int base_object_no;
};

struct base_data {
	struct base_data *base;
	struct base_data *child;
	struct object_entry *obj;
	void *data;
	unsigned long size;
	int ref_first, ref_last;
	int ofs_first, ofs_last;
};

struct thread_local {
	pthread_t thread;
	struct base_data *base_cache;
	size_t base_cache_used;
	int pack_fd;
};

/* Remember to update object flag allocation in object.h */
#define FLAG_LINK (1u<<20)
#define FLAG_CHECKED (1u<<21)

struct ofs_delta_entry {
	off_t offset;
	int obj_no;
};

struct ref_delta_entry {
	struct object_id oid;
	int obj_no;
};

static struct object_entry *objects;
static struct object_stat *obj_stat;
static struct ofs_delta_entry *ofs_deltas;
static struct ref_delta_entry *ref_deltas;
static struct thread_local nothread_data;
static int nr_objects;
static int nr_ofs_deltas;
static int nr_ref_deltas;
static int ref_deltas_alloc;
static int nr_resolved_deltas;
static int nr_threads;

static int from_stdin;
static int strict;
static int do_fsck_object;
static struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
static int verbose;
static int show_resolving_progress;
static int show_stat;
static int check_self_contained_and_connected;

static struct progress *progress;

/* We always read in 4kB chunks. */
static unsigned char input_buffer[4096];
static unsigned int input_offset, input_len;
static off_t consumed_bytes;
static off_t max_input_size;
static unsigned deepest_delta;
static git_hash_ctx input_ctx;
static uint32_t input_crc32;
static int input_fd, output_fd;
static const char *curr_pack;

static struct thread_local *thread_data;
static int nr_dispatched;
static int threads_active;

static pthread_mutex_t read_mutex;
#define read_lock()		lock_mutex(&read_mutex)
#define read_unlock()		unlock_mutex(&read_mutex)

static pthread_mutex_t counter_mutex;
#define counter_lock()		lock_mutex(&counter_mutex)
#define counter_unlock()	unlock_mutex(&counter_mutex)

static pthread_mutex_t work_mutex;
#define work_lock()		lock_mutex(&work_mutex)
#define work_unlock()		unlock_mutex(&work_mutex)

static pthread_mutex_t deepest_delta_mutex;
#define deepest_delta_lock()	lock_mutex(&deepest_delta_mutex)
#define deepest_delta_unlock()	unlock_mutex(&deepest_delta_mutex)

static pthread_mutex_t type_cas_mutex;
#define type_cas_lock()		lock_mutex(&type_cas_mutex)
#define type_cas_unlock()	unlock_mutex(&type_cas_mutex)

static pthread_key_t key;

static inline void lock_mutex(pthread_mutex_t *mutex)
{
	if (threads_active)
		pthread_mutex_lock(mutex);
}

static inline void unlock_mutex(pthread_mutex_t *mutex)
{
	if (threads_active)
		pthread_mutex_unlock(mutex);
}

/*
 * Mutex and conditional variable can't be statically-initialized on Windows.
 */
static void init_thread(void)
{
	int i;
	init_recursive_mutex(&read_mutex);
	pthread_mutex_init(&counter_mutex, NULL);
	pthread_mutex_init(&work_mutex, NULL);
	pthread_mutex_init(&type_cas_mutex, NULL);
	if (show_stat)
		pthread_mutex_init(&deepest_delta_mutex, NULL);
	pthread_key_create(&key, NULL);
	thread_data = xcalloc(nr_threads, sizeof(*thread_data));
	for (i = 0; i < nr_threads; i++) {
		thread_data[i].pack_fd = open(curr_pack, O_RDONLY);
		if (thread_data[i].pack_fd == -1)
			die_errno(_("unable to open %s"), curr_pack);
	}

	threads_active = 1;
}

static void cleanup_thread(void)
{
	int i;
	if (!threads_active)
		return;
	threads_active = 0;
	pthread_mutex_destroy(&read_mutex);
	pthread_mutex_destroy(&counter_mutex);
	pthread_mutex_destroy(&work_mutex);
	pthread_mutex_destroy(&type_cas_mutex);
	if (show_stat)
		pthread_mutex_destroy(&deepest_delta_mutex);
	for (i = 0; i < nr_threads; i++)
		close(thread_data[i].pack_fd);
	pthread_key_delete(key);
	free(thread_data);
}

static int mark_link(struct object *obj, int type, void *data, struct fsck_options *options)
{
	if (!obj)
		return -1;

	if (type != OBJ_ANY && obj->type != type)
		die(_("object type mismatch at %s"), oid_to_hex(&obj->oid));

	obj->flags |= FLAG_LINK;
	return 0;
}

/* The content of each linked object must have been checked
   or it must be already present in the object database */
static unsigned check_object(struct object *obj)
{
	if (!obj)
		return 0;

	if (!(obj->flags & FLAG_LINK))
		return 0;

	if (!(obj->flags & FLAG_CHECKED)) {
		unsigned long size;
		int type = oid_object_info(the_repository, &obj->oid, &size);
		if (type <= 0)
			die(_("did not receive expected object %s"),
			      oid_to_hex(&obj->oid));
		if (type != obj->type)
			die(_("object %s: expected type %s, found %s"),
			    oid_to_hex(&obj->oid),
			    type_name(obj->type), type_name(type));
		obj->flags |= FLAG_CHECKED;
		return 1;
	}

	return 0;
}

static unsigned check_objects(void)
{
	unsigned i, max, foreign_nr = 0;

	max = get_max_object_index();

	if (verbose)
		progress = start_delayed_progress(_("Checking objects"), max);

	for (i = 0; i < max; i++) {
		foreign_nr += check_object(get_indexed_object(i));
		display_progress(progress, i + 1);
	}

	stop_progress(&progress);
	return foreign_nr;
}


/* Discard current buffer used content. */
static void flush(void)
{
	if (input_offset) {
		if (output_fd >= 0)
			write_or_die(output_fd, input_buffer, input_offset);
		the_hash_algo->update_fn(&input_ctx, input_buffer, input_offset);
		memmove(input_buffer, input_buffer + input_offset, input_len);
		input_offset = 0;
	}
}

/*
 * Make sure at least "min" bytes are available in the buffer, and
 * return the pointer to the buffer.
 */
static void *fill(int min)
{
	if (min <= input_len)
		return input_buffer + input_offset;
	if (min > sizeof(input_buffer))
		die(Q_("cannot fill %d byte",
		       "cannot fill %d bytes",
		       min),
		    min);
	flush();
	do {
		ssize_t ret = xread(input_fd, input_buffer + input_len,
				sizeof(input_buffer) - input_len);
		if (ret <= 0) {
			if (!ret)
				die(_("early EOF"));
			die_errno(_("read error on input"));
		}
		input_len += ret;
		if (from_stdin)
			display_throughput(progress, consumed_bytes + input_len);
	} while (input_len < min);
	return input_buffer;
}

static void use(int bytes)
{
	if (bytes > input_len)
		die(_("used more bytes than were available"));
	input_crc32 = crc32(input_crc32, input_buffer + input_offset, bytes);
	input_len -= bytes;
	input_offset += bytes;

	/* make sure off_t is sufficiently large not to wrap */
	if (signed_add_overflows(consumed_bytes, bytes))
		die(_("pack too large for current definition of off_t"));
	consumed_bytes += bytes;
	if (max_input_size && consumed_bytes > max_input_size)
		die(_("pack exceeds maximum allowed size"));
}

static const char *open_pack_file(const char *pack_name)
{
	if (from_stdin) {
		input_fd = 0;
		if (!pack_name) {
			struct strbuf tmp_file = STRBUF_INIT;
			output_fd = odb_mkstemp(&tmp_file,
						"pack/tmp_pack_XXXXXX");
			pack_name = strbuf_detach(&tmp_file, NULL);
		} else {
			output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
			if (output_fd < 0)
				die_errno(_("unable to create '%s'"), pack_name);
		}
		nothread_data.pack_fd = output_fd;
	} else {
		input_fd = open(pack_name, O_RDONLY);
		if (input_fd < 0)
			die_errno(_("cannot open packfile '%s'"), pack_name);
		output_fd = -1;
		nothread_data.pack_fd = input_fd;
	}
	the_hash_algo->init_fn(&input_ctx);
	return pack_name;
}

static void parse_pack_header(void)
{
	struct pack_header *hdr = fill(sizeof(struct pack_header));

	/* Header consistency check */
	if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
		die(_("pack signature mismatch"));
	if (!pack_version_ok(hdr->hdr_version))
		die(_("pack version %"PRIu32" unsupported"),
			ntohl(hdr->hdr_version));

	nr_objects = ntohl(hdr->hdr_entries);
	use(sizeof(struct pack_header));
}

static NORETURN void bad_object(off_t offset, const char *format,
		       ...) __attribute__((format (printf, 2, 3)));

static NORETURN void bad_object(off_t offset, const char *format, ...)
{
	va_list params;
	char buf[1024];

	va_start(params, format);
	vsnprintf(buf, sizeof(buf), format, params);
	va_end(params);
	die(_("pack has bad object at offset %"PRIuMAX": %s"),
	    (uintmax_t)offset, buf);
}

static inline struct thread_local *get_thread_data(void)
{
	if (HAVE_THREADS) {
		if (threads_active)
			return pthread_getspecific(key);
		assert(!threads_active &&
		       "This should only be reached when all threads are gone");
	}
	return &nothread_data;
}

static void set_thread_data(struct thread_local *data)
{
	if (threads_active)
		pthread_setspecific(key, data);
}

static struct base_data *alloc_base_data(void)
{
	struct base_data *base = xcalloc(1, sizeof(struct base_data));
	base->ref_last = -1;
	base->ofs_last = -1;
	return base;
}

static void free_base_data(struct base_data *c)
{
	if (c->data) {
		FREE_AND_NULL(c->data);
		get_thread_data()->base_cache_used -= c->size;
	}
}

static void prune_base_data(struct base_data *retain)
{
	struct base_data *b;
	struct thread_local *data = get_thread_data();
	for (b = data->base_cache;
	     data->base_cache_used > delta_base_cache_limit && b;
	     b = b->child) {
		if (b->data && b != retain)
			free_base_data(b);
	}
}

static void link_base_data(struct base_data *base, struct base_data *c)
{
	if (base)
		base->child = c;
	else
		get_thread_data()->base_cache = c;

	c->base = base;
	c->child = NULL;
	if (c->data)
		get_thread_data()->base_cache_used += c->size;
	prune_base_data(c);
}

static void unlink_base_data(struct base_data *c)
{
	struct base_data *base = c->base;
	if (base)
		base->child = NULL;
	else
		get_thread_data()->base_cache = NULL;
	free_base_data(c);
}

static int is_delta_type(enum object_type type)
{
	return (type == OBJ_REF_DELTA || type == OBJ_OFS_DELTA);
}

static void *unpack_entry_data(off_t offset, unsigned long size,
			       enum object_type type, struct object_id *oid)
{
	static char fixed_buf[8192];
	int status;
	git_zstream stream;
	void *buf;
	git_hash_ctx c;
	char hdr[32];
	int hdrlen;

	if (!is_delta_type(type)) {
		hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX,
				   type_name(type),(uintmax_t)size) + 1;
		the_hash_algo->init_fn(&c);
		the_hash_algo->update_fn(&c, hdr, hdrlen);
	} else
		oid = NULL;
	if (type == OBJ_BLOB && size > big_file_threshold)
		buf = fixed_buf;
	else
		buf = xmallocz(size);

	memset(&stream, 0, sizeof(stream));
	git_inflate_init(&stream);
	stream.next_out = buf;
	stream.avail_out = buf == fixed_buf ? sizeof(fixed_buf) : size;

	do {
		unsigned char *last_out = stream.next_out;
		stream.next_in = fill(1);
		stream.avail_in = input_len;
		status = git_inflate(&stream, 0);
		use(input_len - stream.avail_in);
		if (oid)
			the_hash_algo->update_fn(&c, last_out, stream.next_out - last_out);
		if (buf == fixed_buf) {
			stream.next_out = buf;
			stream.avail_out = sizeof(fixed_buf);
		}
	} while (status == Z_OK);
	if (stream.total_out != size || status != Z_STREAM_END)
		bad_object(offset, _("inflate returned %d"), status);
	git_inflate_end(&stream);
	if (oid)
		the_hash_algo->final_fn(oid->hash, &c);
	return buf == fixed_buf ? NULL : buf;
}

static void *unpack_raw_entry(struct object_entry *obj,
			      off_t *ofs_offset,
			      struct object_id *ref_oid,
			      struct object_id *oid)
{
	unsigned char *p;
	unsigned long size, c;
	off_t base_offset;
	unsigned shift;
	void *data;

	obj->idx.offset = consumed_bytes;
	input_crc32 = crc32(0, NULL, 0);

	p = fill(1);
	c = *p;
	use(1);
	obj->type = (c >> 4) & 7;
	size = (c & 15);
	shift = 4;
	while (c & 0x80) {
		p = fill(1);
		c = *p;
		use(1);
		size += (c & 0x7f) << shift;
		shift += 7;
	}
	obj->size = size;

	switch (obj->type) {
	case OBJ_REF_DELTA:
		hashcpy(ref_oid->hash, fill(the_hash_algo->rawsz));
		use(the_hash_algo->rawsz);
		break;
	case OBJ_OFS_DELTA:
		p = fill(1);
		c = *p;
		use(1);
		base_offset = c & 127;
		while (c & 128) {
			base_offset += 1;
			if (!base_offset || MSB(base_offset, 7))
				bad_object(obj->idx.offset, _("offset value overflow for delta base object"));
			p = fill(1);
			c = *p;
			use(1);
			base_offset = (base_offset << 7) + (c & 127);
		}
		*ofs_offset = obj->idx.offset - base_offset;
		if (*ofs_offset <= 0 || *ofs_offset >= obj->idx.offset)
			bad_object(obj->idx.offset, _("delta base offset is out of bound"));
		break;
	case OBJ_COMMIT:
	case OBJ_TREE:
	case OBJ_BLOB:
	case OBJ_TAG:
		break;
	default:
		bad_object(obj->idx.offset, _("unknown object type %d"), obj->type);
	}
	obj->hdr_size = consumed_bytes - obj->idx.offset;

	data = unpack_entry_data(obj->idx.offset, obj->size, obj->type, oid);
	obj->idx.crc32 = input_crc32;
	return data;
}

static void *unpack_data(struct object_entry *obj,
			 int (*consume)(const unsigned char *, unsigned long, void *),
			 void *cb_data)
{
	off_t from = obj[0].idx.offset + obj[0].hdr_size;
	off_t len = obj[1].idx.offset - from;
	unsigned char *data, *inbuf;
	git_zstream stream;
	int status;

	data = xmallocz(consume ? 64*1024 : obj->size);
	inbuf = xmalloc((len < 64*1024) ? (int)len : 64*1024);

	memset(&stream, 0, sizeof(stream));
	git_inflate_init(&stream);
	stream.next_out = data;
	stream.avail_out = consume ? 64*1024 : obj->size;

	do {
		ssize_t n = (len < 64*1024) ? (ssize_t)len : 64*1024;
		n = xpread(get_thread_data()->pack_fd, inbuf, n, from);
		if (n < 0)
			die_errno(_("cannot pread pack file"));
		if (!n)
			die(Q_("premature end of pack file, %"PRIuMAX" byte missing",
			       "premature end of pack file, %"PRIuMAX" bytes missing",
			       (unsigned int)len),
			    (uintmax_t)len);
		from += n;
		len -= n;
		stream.next_in = inbuf;
		stream.avail_in = n;
		if (!consume)
			status = git_inflate(&stream, 0);
		else {
			do {
				status = git_inflate(&stream, 0);
				if (consume(data, stream.next_out - data, cb_data)) {
					free(inbuf);
					free(data);
					return NULL;
				}
				stream.next_out = data;
				stream.avail_out = 64*1024;
			} while (status == Z_OK && stream.avail_in);
		}
	} while (len && status == Z_OK && !stream.avail_in);

	/* This has been inflated OK when first encountered, so... */
	if (status != Z_STREAM_END || stream.total_out != obj->size)
		die(_("serious inflate inconsistency"));

	git_inflate_end(&stream);
	free(inbuf);
	if (consume) {
		FREE_AND_NULL(data);
	}
	return data;
}

static void *get_data_from_pack(struct object_entry *obj)
{
	return unpack_data(obj, NULL, NULL);
}

static int compare_ofs_delta_bases(off_t offset1, off_t offset2,
				   enum object_type type1,
				   enum object_type type2)
{
	int cmp = type1 - type2;
	if (cmp)
		return cmp;
	return offset1 < offset2 ? -1 :
	       offset1 > offset2 ?  1 :
	       0;
}

static int find_ofs_delta(const off_t offset, enum object_type type)
{
	int first = 0, last = nr_ofs_deltas;

	while (first < last) {
		int next = first + (last - first) / 2;
		struct ofs_delta_entry *delta = &ofs_deltas[next];
		int cmp;

		cmp = compare_ofs_delta_bases(offset, delta->offset,
					      type, objects[delta->obj_no].type);
		if (!cmp)
			return next;
		if (cmp < 0) {
			last = next;
			continue;
		}
		first = next+1;
	}
	return -first-1;
}

static void find_ofs_delta_children(off_t offset,
				    int *first_index, int *last_index,
				    enum object_type type)
{
	int first = find_ofs_delta(offset, type);
	int last = first;
	int end = nr_ofs_deltas - 1;

	if (first < 0) {
		*first_index = 0;
		*last_index = -1;
		return;
	}
	while (first > 0 && ofs_deltas[first - 1].offset == offset)
		--first;
	while (last < end && ofs_deltas[last + 1].offset == offset)
		++last;
	*first_index = first;
	*last_index = last;
}

static int compare_ref_delta_bases(const struct object_id *oid1,
				   const struct object_id *oid2,
				   enum object_type type1,
				   enum object_type type2)
{
	int cmp = type1 - type2;
	if (cmp)
		return cmp;
	return oidcmp(oid1, oid2);
}

static int find_ref_delta(const struct object_id *oid, enum object_type type)
{
	int first = 0, last = nr_ref_deltas;

	while (first < last) {
		int next = first + (last - first) / 2;
		struct ref_delta_entry *delta = &ref_deltas[next];
		int cmp;

		cmp = compare_ref_delta_bases(oid, &delta->oid,
					      type, objects[delta->obj_no].type);
		if (!cmp)
			return next;
		if (cmp < 0) {
			last = next;
			continue;
		}
		first = next+1;
	}
	return -first-1;
}

static void find_ref_delta_children(const struct object_id *oid,
				    int *first_index, int *last_index,
				    enum object_type type)
{
	int first = find_ref_delta(oid, type);
	int last = first;
	int end = nr_ref_deltas - 1;

	if (first < 0) {
		*first_index = 0;
		*last_index = -1;
		return;
	}
	while (first > 0 && oideq(&ref_deltas[first - 1].oid, oid))
		--first;
	while (last < end && oideq(&ref_deltas[last + 1].oid, oid))
		++last;
	*first_index = first;
	*last_index = last;
}

struct compare_data {
	struct object_entry *entry;
	struct git_istream *st;
	unsigned char *buf;
	unsigned long buf_size;
};

static int compare_objects(const unsigned char *buf, unsigned long size,
			   void *cb_data)
{
	struct compare_data *data = cb_data;

	if (data->buf_size < size) {
		free(data->buf);
		data->buf = xmalloc(size);
		data->buf_size = size;
	}

	while (size) {
		ssize_t len = read_istream(data->st, data->buf, size);
		if (len == 0)
			die(_("SHA1 COLLISION FOUND WITH %s !"),
			    oid_to_hex(&data->entry->idx.oid));
		if (len < 0)
			die(_("unable to read %s"),
			    oid_to_hex(&data->entry->idx.oid));
		if (memcmp(buf, data->buf, len))
			die(_("SHA1 COLLISION FOUND WITH %s !"),
			    oid_to_hex(&data->entry->idx.oid));
		size -= len;
		buf += len;
	}
	return 0;
}

static int check_collison(struct object_entry *entry)
{
	struct compare_data data;
	enum object_type type;
	unsigned long size;

	if (entry->size <= big_file_threshold || entry->type != OBJ_BLOB)
		return -1;

	memset(&data, 0, sizeof(data));
	data.entry = entry;
	data.st = open_istream(&entry->idx.oid, &type, &size, NULL);
	if (!data.st)
		return -1;
	if (size != entry->size || type != entry->type)
		die(_("SHA1 COLLISION FOUND WITH %s !"),
		    oid_to_hex(&entry->idx.oid));
	unpack_data(entry, compare_objects, &data);
	close_istream(data.st);
	free(data.buf);
	return 0;
}

static void sha1_object(const void *data, struct object_entry *obj_entry,
			unsigned long size, enum object_type type,
			const struct object_id *oid)
{
	void *new_data = NULL;
	int collision_test_needed = 0;

	assert(data || obj_entry);

	if (startup_info->have_repository) {
		read_lock();
		collision_test_needed =
			has_object_file_with_flags(oid, OBJECT_INFO_QUICK);
		read_unlock();
	}

	if (collision_test_needed && !data) {
		read_lock();
		if (!check_collison(obj_entry))
			collision_test_needed = 0;
		read_unlock();
	}
	if (collision_test_needed) {
		void *has_data;
		enum object_type has_type;
		unsigned long has_size;
		read_lock();
		has_type = oid_object_info(the_repository, oid, &has_size);
		if (has_type < 0)
			die(_("cannot read existing object info %s"), oid_to_hex(oid));
		if (has_type != type || has_size != size)
			die(_("SHA1 COLLISION FOUND WITH %s !"), oid_to_hex(oid));
		has_data = read_object_file(oid, &has_type, &has_size);
		read_unlock();
		if (!data)
			data = new_data = get_data_from_pack(obj_entry);
		if (!has_data)
			die(_("cannot read existing object %s"), oid_to_hex(oid));
		if (size != has_size || type != has_type ||
		    memcmp(data, has_data, size) != 0)
			die(_("SHA1 COLLISION FOUND WITH %s !"), oid_to_hex(oid));
		free(has_data);
	}

	if (strict || do_fsck_object) {
		read_lock();
		if (type == OBJ_BLOB) {
			struct blob *blob = lookup_blob(the_repository, oid);
			if (blob)
				blob->object.flags |= FLAG_CHECKED;
			else
				die(_("invalid blob object %s"), oid_to_hex(oid));
			if (do_fsck_object &&
			    fsck_object(&blob->object, (void *)data, size, &fsck_options))
				die(_("fsck error in packed object"));
		} else {
			struct object *obj;
			int eaten;
			void *buf = (void *) data;

			assert(data && "data can only be NULL for large _blobs_");

			/*
			 * we do not need to free the memory here, as the
			 * buf is deleted by the caller.
			 */
			obj = parse_object_buffer(the_repository, oid, type,
						  size, buf,
						  &eaten);
			if (!obj)
				die(_("invalid %s"), type_name(type));
			if (do_fsck_object &&
			    fsck_object(obj, buf, size, &fsck_options))
				die(_("fsck error in packed object"));
			if (strict && fsck_walk(obj, NULL, &fsck_options))
				die(_("Not all child objects of %s are reachable"), oid_to_hex(&obj->oid));

			if (obj->type == OBJ_TREE) {
				struct tree *item = (struct tree *) obj;
				item->buffer = NULL;
				obj->parsed = 0;
			}
			if (obj->type == OBJ_COMMIT) {
				struct commit *commit = (struct commit *) obj;
				if (detach_commit_buffer(commit, NULL) != data)
					BUG("parse_object_buffer transmogrified our buffer");
			}
			obj->flags |= FLAG_CHECKED;
		}
		read_unlock();
	}

	free(new_data);
}

/*
 * This function is part of find_unresolved_deltas(). There are two
 * walkers going in the opposite ways.
 *
 * The first one in find_unresolved_deltas() traverses down from
 * parent node to children, deflating nodes along the way. However,
 * memory for deflated nodes is limited by delta_base_cache_limit, so
 * at some point parent node's deflated content may be freed.
 *
 * The second walker is this function, which goes from current node up
 * to top parent if necessary to deflate the node. In normal
 * situation, its parent node would be already deflated, so it just
 * needs to apply delta.
 *
 * In the worst case scenario, parent node is no longer deflated because
 * we're running out of delta_base_cache_limit; we need to re-deflate
 * parents, possibly up to the top base.
 *
 * All deflated objects here are subject to be freed if we exceed
 * delta_base_cache_limit, just like in find_unresolved_deltas(), we
 * just need to make sure the last node is not freed.
 */
static void *get_base_data(struct base_data *c)
{
	if (!c->data) {
		struct object_entry *obj = c->obj;
		struct base_data **delta = NULL;
		int delta_nr = 0, delta_alloc = 0;

		while (is_delta_type(c->obj->type) && !c->data) {
			ALLOC_GROW(delta, delta_nr + 1, delta_alloc);
			delta[delta_nr++] = c;
			c = c->base;
		}
		if (!delta_nr) {
			c->data = get_data_from_pack(obj);
			c->size = obj->size;
			get_thread_data()->base_cache_used += c->size;
			prune_base_data(c);
		}
		for (; delta_nr > 0; delta_nr--) {
			void *base, *raw;
			c = delta[delta_nr - 1];
			obj = c->obj;
			base = get_base_data(c->base);
			raw = get_data_from_pack(obj);
			c->data = patch_delta(
				base, c->base->size,
				raw, obj->size,
				&c->size);
			free(raw);
			if (!c->data)
				bad_object(obj->idx.offset, _("failed to apply delta"));
			get_thread_data()->base_cache_used += c->size;
			prune_base_data(c);
		}
		free(delta);
	}
	return c->data;
}

static void resolve_delta(struct object_entry *delta_obj,
			  struct base_data *base, struct base_data *result)
{
	void *base_data, *delta_data;

	if (show_stat) {
		int i = delta_obj - objects;
		int j = base->obj - objects;
		obj_stat[i].delta_depth = obj_stat[j].delta_depth + 1;
		deepest_delta_lock();
		if (deepest_delta < obj_stat[i].delta_depth)
			deepest_delta = obj_stat[i].delta_depth;
		deepest_delta_unlock();
		obj_stat[i].base_object_no = j;
	}
	delta_data = get_data_from_pack(delta_obj);
	base_data = get_base_data(base);
	result->obj = delta_obj;
	result->data = patch_delta(base_data, base->size,
				   delta_data, delta_obj->size, &result->size);
	free(delta_data);
	if (!result->data)
		bad_object(delta_obj->idx.offset, _("failed to apply delta"));
	hash_object_file(result->data, result->size,
			 type_name(delta_obj->real_type), &delta_obj->idx.oid);
	sha1_object(result->data, NULL, result->size, delta_obj->real_type,
		    &delta_obj->idx.oid);
	counter_lock();
	nr_resolved_deltas++;
	counter_unlock();
}

/*
 * Standard boolean compare-and-swap: atomically check whether "*type" is
 * "want"; if so, swap in "set" and return true. Otherwise, leave it untouched
 * and return false.
 */
static int compare_and_swap_type(signed char *type,
				 enum object_type want,
				 enum object_type set)
{
	enum object_type old;

	type_cas_lock();
	old = *type;
	if (old == want)
		*type = set;
	type_cas_unlock();

	return old == want;
}

static struct base_data *find_unresolved_deltas_1(struct base_data *base,
						  struct base_data *prev_base)
{
	if (base->ref_last == -1 && base->ofs_last == -1) {
		find_ref_delta_children(&base->obj->idx.oid,
					&base->ref_first, &base->ref_last,
					OBJ_REF_DELTA);

		find_ofs_delta_children(base->obj->idx.offset,
					&base->ofs_first, &base->ofs_last,
					OBJ_OFS_DELTA);

		if (base->ref_last == -1 && base->ofs_last == -1) {
			free(base->data);
			return NULL;
		}

		link_base_data(prev_base, base);
	}

	if (base->ref_first <= base->ref_last) {
		struct object_entry *child = objects + ref_deltas[base->ref_first].obj_no;
		struct base_data *result = alloc_base_data();

		if (!compare_and_swap_type(&child->real_type, OBJ_REF_DELTA,
					   base->obj->real_type))
			BUG("child->real_type != OBJ_REF_DELTA");

		resolve_delta(child, base, result);
		if (base->ref_first == base->ref_last && base->ofs_last == -1)
			free_base_data(base);

		base->ref_first++;
		return result;
	}

	if (base->ofs_first <= base->ofs_last) {
		struct object_entry *child = objects + ofs_deltas[base->ofs_first].obj_no;
		struct base_data *result = alloc_base_data();

		assert(child->real_type == OBJ_OFS_DELTA);
		child->real_type = base->obj->real_type;
		resolve_delta(child, base, result);
		if (base->ofs_first == base->ofs_last)
			free_base_data(base);

		base->ofs_first++;
		return result;
	}

	unlink_base_data(base);
	return NULL;
}

static void find_unresolved_deltas(struct base_data *base)
{
	struct base_data *new_base, *prev_base = NULL;
	for (;;) {
		new_base = find_unresolved_deltas_1(base, prev_base);

		if (new_base) {
			prev_base = base;
			base = new_base;
		} else {
			free(base);
			base = prev_base;
			if (!base)
				return;
			prev_base = base->base;
		}
	}
}

static int compare_ofs_delta_entry(const void *a, const void *b)
{
	const struct ofs_delta_entry *delta_a = a;
	const struct ofs_delta_entry *delta_b = b;

	return delta_a->offset < delta_b->offset ? -1 :
	       delta_a->offset > delta_b->offset ?  1 :
	       0;
}

static int compare_ref_delta_entry(const void *a, const void *b)
{
	const struct ref_delta_entry *delta_a = a;
	const struct ref_delta_entry *delta_b = b;

	return oidcmp(&delta_a->oid, &delta_b->oid);
}

static void resolve_base(struct object_entry *obj)
{
	struct base_data *base_obj = alloc_base_data();
	base_obj->obj = obj;
	base_obj->data = NULL;
	find_unresolved_deltas(base_obj);
}

static void *threaded_second_pass(void *data)
{
	set_thread_data(data);
	for (;;) {
		int i;
		counter_lock();
		display_progress(progress, nr_resolved_deltas);
		counter_unlock();
		work_lock();
		while (nr_dispatched < nr_objects &&
		       is_delta_type(objects[nr_dispatched].type))
			nr_dispatched++;
		if (nr_dispatched >= nr_objects) {
			work_unlock();
			break;
		}
		i = nr_dispatched++;
		work_unlock();

		resolve_base(&objects[i]);
	}
	return NULL;
}

/*
 * First pass:
 * - find locations of all objects;
 * - calculate SHA1 of all non-delta objects;
 * - remember base (SHA1 or offset) for all deltas.
 */
static void parse_pack_objects(unsigned char *hash)
{
	int i, nr_delays = 0;
	struct ofs_delta_entry *ofs_delta = ofs_deltas;
	struct object_id ref_delta_oid;
	struct stat st;

	if (verbose)
		progress = start_progress(
				from_stdin ? _("Receiving objects") : _("Indexing objects"),
				nr_objects);
	for (i = 0; i < nr_objects; i++) {
		struct object_entry *obj = &objects[i];
		void *data = unpack_raw_entry(obj, &ofs_delta->offset,
					      &ref_delta_oid,
					      &obj->idx.oid);
		obj->real_type = obj->type;
		if (obj->type == OBJ_OFS_DELTA) {
			nr_ofs_deltas++;
			ofs_delta->obj_no = i;
			ofs_delta++;
		} else if (obj->type == OBJ_REF_DELTA) {
			ALLOC_GROW(ref_deltas, nr_ref_deltas + 1, ref_deltas_alloc);
			oidcpy(&ref_deltas[nr_ref_deltas].oid, &ref_delta_oid);
			ref_deltas[nr_ref_deltas].obj_no = i;
			nr_ref_deltas++;
		} else if (!data) {
			/* large blobs, check later */
			obj->real_type = OBJ_BAD;
			nr_delays++;
		} else
			sha1_object(data, NULL, obj->size, obj->type,
				    &obj->idx.oid);
		free(data);
		display_progress(progress, i+1);
	}
	objects[i].idx.offset = consumed_bytes;
	stop_progress(&progress);

	/* Check pack integrity */
	flush();
	the_hash_algo->final_fn(hash, &input_ctx);
	if (!hasheq(fill(the_hash_algo->rawsz), hash))
		die(_("pack is corrupted (SHA1 mismatch)"));
	use(the_hash_algo->rawsz);

	/* If input_fd is a file, we should have reached its end now. */
	if (fstat(input_fd, &st))
		die_errno(_("cannot fstat packfile"));
	if (S_ISREG(st.st_mode) &&
			lseek(input_fd, 0, SEEK_CUR) - input_len != st.st_size)
		die(_("pack has junk at the end"));

	for (i = 0; i < nr_objects; i++) {
		struct object_entry *obj = &objects[i];
		if (obj->real_type != OBJ_BAD)
			continue;
		obj->real_type = obj->type;
		sha1_object(NULL, obj, obj->size, obj->type,
			    &obj->idx.oid);
		nr_delays--;
	}
	if (nr_delays)
		die(_("confusion beyond insanity in parse_pack_objects()"));
}

/*
 * Second pass:
 * - for all non-delta objects, look if it is used as a base for
 *   deltas;
 * - if used as a base, uncompress the object and apply all deltas,
 *   recursively checking if the resulting object is used as a base
 *   for some more deltas.
 */
static void resolve_deltas(void)
{
	int i;

	if (!nr_ofs_deltas && !nr_ref_deltas)
		return;

	/* Sort deltas by base SHA1/offset for fast searching */
	QSORT(ofs_deltas, nr_ofs_deltas, compare_ofs_delta_entry);
	QSORT(ref_deltas, nr_ref_deltas, compare_ref_delta_entry);

	if (verbose || show_resolving_progress)
		progress = start_progress(_("Resolving deltas"),
					  nr_ref_deltas + nr_ofs_deltas);

	nr_dispatched = 0;
	if (nr_threads > 1 || getenv("GIT_FORCE_THREADS")) {
		init_thread();
		for (i = 0; i < nr_threads; i++) {
			int ret = pthread_create(&thread_data[i].thread, NULL,
						 threaded_second_pass, thread_data + i);
			if (ret)
				die(_("unable to create thread: %s"),
				    strerror(ret));
		}
		for (i = 0; i < nr_threads; i++)
			pthread_join(thread_data[i].thread, NULL);
		cleanup_thread();
		return;
	}

	for (i = 0; i < nr_objects; i++) {
		struct object_entry *obj = &objects[i];

		if (is_delta_type(obj->type))
			continue;
		resolve_base(obj);
		display_progress(progress, nr_resolved_deltas);
	}
}

/*
 * Third pass:
 * - append objects to convert thin pack to full pack if required
 * - write the final pack hash
 */
static void fix_unresolved_deltas(struct hashfile *f);
static void conclude_pack(int fix_thin_pack, const char *curr_pack, unsigned char *pack_hash)
{
	if (nr_ref_deltas + nr_ofs_deltas == nr_resolved_deltas) {
		stop_progress(&progress);
		/* Flush remaining pack final hash. */
		flush();
		return;
	}

	if (fix_thin_pack) {
		struct hashfile *f;
		unsigned char read_hash[GIT_MAX_RAWSZ], tail_hash[GIT_MAX_RAWSZ];
		struct strbuf msg = STRBUF_INIT;
		int nr_unresolved = nr_ofs_deltas + nr_ref_deltas - nr_resolved_deltas;
		int nr_objects_initial = nr_objects;
		if (nr_unresolved <= 0)
			die(_("confusion beyond insanity"));
		REALLOC_ARRAY(objects, nr_objects + nr_unresolved + 1);
		memset(objects + nr_objects + 1, 0,
		       nr_unresolved * sizeof(*objects));
		f = hashfd(output_fd, curr_pack);
		fix_unresolved_deltas(f);
		strbuf_addf(&msg, Q_("completed with %d local object",
				     "completed with %d local objects",
				     nr_objects - nr_objects_initial),
			    nr_objects - nr_objects_initial);
		stop_progress_msg(&progress, msg.buf);
		strbuf_release(&msg);
		finalize_hashfile(f, tail_hash, 0);
		hashcpy(read_hash, pack_hash);
		fixup_pack_header_footer(output_fd, pack_hash,
					 curr_pack, nr_objects,
					 read_hash, consumed_bytes-the_hash_algo->rawsz);
		if (!hasheq(read_hash, tail_hash))
			die(_("Unexpected tail checksum for %s "
			      "(disk corruption?)"), curr_pack);
	}
	if (nr_ofs_deltas + nr_ref_deltas != nr_resolved_deltas)
		die(Q_("pack has %d unresolved delta",
		       "pack has %d unresolved deltas",
		       nr_ofs_deltas + nr_ref_deltas - nr_resolved_deltas),
		    nr_ofs_deltas + nr_ref_deltas - nr_resolved_deltas);
}

static int write_compressed(struct hashfile *f, void *in, unsigned int size)
{
	git_zstream stream;
	int status;
	unsigned char outbuf[4096];

	git_deflate_init(&stream, zlib_compression_level);
	stream.next_in = in;
	stream.avail_in = size;

	do {
		stream.next_out = outbuf;
		stream.avail_out = sizeof(outbuf);
		status = git_deflate(&stream, Z_FINISH);
		hashwrite(f, outbuf, sizeof(outbuf) - stream.avail_out);
	} while (status == Z_OK);

	if (status != Z_STREAM_END)
		die(_("unable to deflate appended object (%d)"), status);
	size = stream.total_out;
	git_deflate_end(&stream);
	return size;
}

static struct object_entry *append_obj_to_pack(struct hashfile *f,
			       const unsigned char *sha1, void *buf,
			       unsigned long size, enum object_type type)
{
	struct object_entry *obj = &objects[nr_objects++];
	unsigned char header[10];
	unsigned long s = size;
	int n = 0;
	unsigned char c = (type << 4) | (s & 15);
	s >>= 4;
	while (s) {
		header[n++] = c | 0x80;
		c = s & 0x7f;
		s >>= 7;
	}
	header[n++] = c;
	crc32_begin(f);
	hashwrite(f, header, n);
	obj[0].size = size;
	obj[0].hdr_size = n;
	obj[0].type = type;
	obj[0].real_type = type;
	obj[1].idx.offset = obj[0].idx.offset + n;
	obj[1].idx.offset += write_compressed(f, buf, size);
	obj[0].idx.crc32 = crc32_end(f);
	hashflush(f);
	hashcpy(obj->idx.oid.hash, sha1);
	return obj;
}

static int delta_pos_compare(const void *_a, const void *_b)
{
	struct ref_delta_entry *a = *(struct ref_delta_entry **)_a;
	struct ref_delta_entry *b = *(struct ref_delta_entry **)_b;
	return a->obj_no - b->obj_no;
}

static void fix_unresolved_deltas(struct hashfile *f)
{
	struct ref_delta_entry **sorted_by_pos;
	int i;

	/*
	 * Since many unresolved deltas may well be themselves base objects
	 * for more unresolved deltas, we really want to include the
	 * smallest number of base objects that would cover as much delta
	 * as possible by picking the
	 * trunc deltas first, allowing for other deltas to resolve without
	 * additional base objects.  Since most base objects are to be found
	 * before deltas depending on them, a good heuristic is to start
	 * resolving deltas in the same order as their position in the pack.
	 */
	ALLOC_ARRAY(sorted_by_pos, nr_ref_deltas);
	for (i = 0; i < nr_ref_deltas; i++)
		sorted_by_pos[i] = &ref_deltas[i];
	QSORT(sorted_by_pos, nr_ref_deltas, delta_pos_compare);

	if (repository_format_partial_clone) {
		/*
		 * Prefetch the delta bases.
		 */
		struct oid_array to_fetch = OID_ARRAY_INIT;
		for (i = 0; i < nr_ref_deltas; i++) {
			struct ref_delta_entry *d = sorted_by_pos[i];
			if (!oid_object_info_extended(the_repository, &d->oid,
						      NULL,
						      OBJECT_INFO_FOR_PREFETCH))
				continue;
			oid_array_append(&to_fetch, &d->oid);
		}
		if (to_fetch.nr)
			fetch_objects(repository_format_partial_clone,
				      to_fetch.oid, to_fetch.nr);
		oid_array_clear(&to_fetch);
	}

	for (i = 0; i < nr_ref_deltas; i++) {
		struct ref_delta_entry *d = sorted_by_pos[i];
		enum object_type type;
		struct base_data *base_obj = alloc_base_data();

		if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
			continue;
		base_obj->data = read_object_file(&d->oid, &type,
						  &base_obj->size);
		if (!base_obj->data)
			continue;

		if (check_object_signature(&d->oid, base_obj->data,
				base_obj->size, type_name(type)))
			die(_("local object %s is corrupt"), oid_to_hex(&d->oid));
		base_obj->obj = append_obj_to_pack(f, d->oid.hash,
					base_obj->data, base_obj->size, type);
		find_unresolved_deltas(base_obj);
		display_progress(progress, nr_resolved_deltas);
	}
	free(sorted_by_pos);
}

static const char *derive_filename(const char *pack_name, const char *suffix,
				   struct strbuf *buf)
{
	size_t len;
	if (!strip_suffix(pack_name, ".pack", &len))
		die(_("packfile name '%s' does not end with '.pack'"),
		    pack_name);
	strbuf_add(buf, pack_name, len);
	strbuf_addch(buf, '.');
	strbuf_addstr(buf, suffix);
	return buf->buf;
}

static void write_special_file(const char *suffix, const char *msg,
			       const char *pack_name, const unsigned char *hash,
			       const char **report)
{
	struct strbuf name_buf = STRBUF_INIT;
	const char *filename;
	int fd;
	int msg_len = strlen(msg);

	if (pack_name)
		filename = derive_filename(pack_name, suffix, &name_buf);
	else
		filename = odb_pack_name(&name_buf, hash, suffix);

	fd = odb_pack_keep(filename);
	if (fd < 0) {
		if (errno != EEXIST)
			die_errno(_("cannot write %s file '%s'"),
				  suffix, filename);
	} else {
		if (msg_len > 0) {
			write_or_die(fd, msg, msg_len);
			write_or_die(fd, "\n", 1);
		}
		if (close(fd) != 0)
			die_errno(_("cannot close written %s file '%s'"),
				  suffix, filename);
		if (report)
			*report = suffix;
	}
	strbuf_release(&name_buf);
}

static void final(const char *final_pack_name, const char *curr_pack_name,
		  const char *final_index_name, const char *curr_index_name,
		  const char *keep_msg, const char *promisor_msg,
		  unsigned char *hash)
{
	const char *report = "pack";
	struct strbuf pack_name = STRBUF_INIT;
	struct strbuf index_name = STRBUF_INIT;
	int err;

	if (!from_stdin) {
		close(input_fd);
	} else {
		fsync_or_die(output_fd, curr_pack_name);
		err = close(output_fd);
		if (err)
			die_errno(_("error while closing pack file"));
	}

	if (keep_msg)
		write_special_file("keep", keep_msg, final_pack_name, hash,
				   &report);
	if (promisor_msg)
		write_special_file("promisor", promisor_msg, final_pack_name,
				   hash, NULL);

	if (final_pack_name != curr_pack_name) {
		if (!final_pack_name)
			final_pack_name = odb_pack_name(&pack_name, hash, "pack");
		if (finalize_object_file(curr_pack_name, final_pack_name))
			die(_("cannot store pack file"));
	} else if (from_stdin)
		chmod(final_pack_name, 0444);

	if (final_index_name != curr_index_name) {
		if (!final_index_name)
			final_index_name = odb_pack_name(&index_name, hash, "idx");
		if (finalize_object_file(curr_index_name, final_index_name))
			die(_("cannot store index file"));
	} else
		chmod(final_index_name, 0444);

	if (do_fsck_object) {
		struct packed_git *p;
		p = add_packed_git(final_index_name, strlen(final_index_name), 0);
		if (p)
			install_packed_git(the_repository, p);
	}

	if (!from_stdin) {
		printf("%s\n", sha1_to_hex(hash));
	} else {
		struct strbuf buf = STRBUF_INIT;

		strbuf_addf(&buf, "%s\t%s\n", report, sha1_to_hex(hash));
		write_or_die(1, buf.buf, buf.len);
		strbuf_release(&buf);

		/*
		 * Let's just mimic git-unpack-objects here and write
		 * the last part of the input buffer to stdout.
		 */
		while (input_len) {
			err = xwrite(1, input_buffer + input_offset, input_len);
			if (err <= 0)
				break;
			input_len -= err;
			input_offset += err;
		}
	}

	strbuf_release(&index_name);
	strbuf_release(&pack_name);
}

static int git_index_pack_config(const char *k, const char *v, void *cb)
{
	struct pack_idx_option *opts = cb;

	if (!strcmp(k, "pack.indexversion")) {
		opts->version = git_config_int(k, v);
		if (opts->version > 2)
			die(_("bad pack.indexversion=%"PRIu32), opts->version);
		return 0;
	}
	if (!strcmp(k, "pack.threads")) {
		nr_threads = git_config_int(k, v);
		if (nr_threads < 0)
			die(_("invalid number of threads specified (%d)"),
			    nr_threads);
		if (!HAVE_THREADS && nr_threads != 1) {
			warning(_("no threads support, ignoring %s"), k);
			nr_threads = 1;
		}
		return 0;
	}
	return git_default_config(k, v, cb);
}

static int cmp_uint32(const void *a_, const void *b_)
{
	uint32_t a = *((uint32_t *)a_);
	uint32_t b = *((uint32_t *)b_);

	return (a < b) ? -1 : (a != b);
}

static void read_v2_anomalous_offsets(struct packed_git *p,
				      struct pack_idx_option *opts)
{
	const uint32_t *idx1, *idx2;
	uint32_t i;
	const uint32_t hashwords = the_hash_algo->rawsz / sizeof(uint32_t);

	/* The address of the 4-byte offset table */
	idx1 = (((const uint32_t *)p->index_data)
		+ 2 /* 8-byte header */
		+ 256 /* fan out */
		+ hashwords * p->num_objects /* object ID table */
		+ p->num_objects /* CRC32 table */
		);

	/* The address of the 8-byte offset table */
	idx2 = idx1 + p->num_objects;

	for (i = 0; i < p->num_objects; i++) {
		uint32_t off = ntohl(idx1[i]);
		if (!(off & 0x80000000))
			continue;
		off = off & 0x7fffffff;
		check_pack_index_ptr(p, &idx2[off * 2]);
		if (idx2[off * 2])
			continue;
		/*
		 * The real offset is ntohl(idx2[off * 2]) in high 4
		 * octets, and ntohl(idx2[off * 2 + 1]) in low 4
		 * octets.  But idx2[off * 2] is Zero!!!
		 */
		ALLOC_GROW(opts->anomaly, opts->anomaly_nr + 1, opts->anomaly_alloc);
		opts->anomaly[opts->anomaly_nr++] = ntohl(idx2[off * 2 + 1]);
	}

	QSORT(opts->anomaly, opts->anomaly_nr, cmp_uint32);
}

static void read_idx_option(struct pack_idx_option *opts, const char *pack_name)
{
	struct packed_git *p = add_packed_git(pack_name, strlen(pack_name), 1);

	if (!p)
		die(_("Cannot open existing pack file '%s'"), pack_name);
	if (open_pack_index(p))
		die(_("Cannot open existing pack idx file for '%s'"), pack_name);

	/* Read the attributes from the existing idx file */
	opts->version = p->index_version;

	if (opts->version == 2)
		read_v2_anomalous_offsets(p, opts);

	/*
	 * Get rid of the idx file as we do not need it anymore.
	 * NEEDSWORK: extract this bit from free_pack_by_name() in
	 * sha1-file.c, perhaps?  It shouldn't matter very much as we
	 * know we haven't installed this pack (hence we never have
	 * read anything from it).
	 */
	close_pack_index(p);
	free(p);
}

static void show_pack_info(int stat_only)
{
	int i, baseobjects = nr_objects - nr_ref_deltas - nr_ofs_deltas;
	unsigned long *chain_histogram = NULL;

	if (deepest_delta)
		chain_histogram = xcalloc(deepest_delta, sizeof(unsigned long));

	for (i = 0; i < nr_objects; i++) {
		struct object_entry *obj = &objects[i];

		if (is_delta_type(obj->type))
			chain_histogram[obj_stat[i].delta_depth - 1]++;
		if (stat_only)
			continue;
		printf("%s %-6s %"PRIuMAX" %"PRIuMAX" %"PRIuMAX,
		       oid_to_hex(&obj->idx.oid),
		       type_name(obj->real_type), (uintmax_t)obj->size,
		       (uintmax_t)(obj[1].idx.offset - obj->idx.offset),
		       (uintmax_t)obj->idx.offset);
		if (is_delta_type(obj->type)) {
			struct object_entry *bobj = &objects[obj_stat[i].base_object_no];
			printf(" %u %s", obj_stat[i].delta_depth,
			       oid_to_hex(&bobj->idx.oid));
		}
		putchar('\n');
	}

	if (baseobjects)
		printf_ln(Q_("non delta: %d object",
			     "non delta: %d objects",
			     baseobjects),
			  baseobjects);
	for (i = 0; i < deepest_delta; i++) {
		if (!chain_histogram[i])
			continue;
		printf_ln(Q_("chain length = %d: %lu object",
			     "chain length = %d: %lu objects",
			     chain_histogram[i]),
			  i + 1,
			  chain_histogram[i]);
	}
}

int cmd_index_pack(int argc, const char **argv, const char *prefix)
{
	int i, fix_thin_pack = 0, verify = 0, stat_only = 0;
	const char *curr_index;
	const char *index_name = NULL, *pack_name = NULL;
	const char *keep_msg = NULL;
	const char *promisor_msg = NULL;
	struct strbuf index_name_buf = STRBUF_INIT;
	struct pack_idx_entry **idx_objects;
	struct pack_idx_option opts;
	unsigned char pack_hash[GIT_MAX_RAWSZ];
	unsigned foreign_nr = 1;	/* zero is a "good" value, assume bad */
	int report_end_of_input = 0;

	/*
	 * index-pack never needs to fetch missing objects except when
	 * REF_DELTA bases are missing (which are explicitly handled). It only
	 * accesses the repo to do hash collision checks and to check which
	 * REF_DELTA bases need to be fetched.
	 */
	fetch_if_missing = 0;

	if (argc == 2 && !strcmp(argv[1], "-h"))
		usage(index_pack_usage);

	read_replace_refs = 0;
	fsck_options.walk = mark_link;

	reset_pack_idx_option(&opts);
	git_config(git_index_pack_config, &opts);
	if (prefix && chdir(prefix))
		die(_("Cannot come back to cwd"));

	for (i = 1; i < argc; i++) {
		const char *arg = argv[i];

		if (*arg == '-') {
			if (!strcmp(arg, "--stdin")) {
				from_stdin = 1;
			} else if (!strcmp(arg, "--fix-thin")) {
				fix_thin_pack = 1;
			} else if (skip_to_optional_arg(arg, "--strict", &arg)) {
				strict = 1;
				do_fsck_object = 1;
				fsck_set_msg_types(&fsck_options, arg);
			} else if (!strcmp(arg, "--check-self-contained-and-connected")) {
				strict = 1;
				check_self_contained_and_connected = 1;
			} else if (!strcmp(arg, "--fsck-objects")) {
				do_fsck_object = 1;
			} else if (!strcmp(arg, "--verify")) {
				verify = 1;
			} else if (!strcmp(arg, "--verify-stat")) {
				verify = 1;
				show_stat = 1;
			} else if (!strcmp(arg, "--verify-stat-only")) {
				verify = 1;
				show_stat = 1;
				stat_only = 1;
			} else if (skip_to_optional_arg(arg, "--keep", &keep_msg)) {
				; /* nothing to do */
			} else if (skip_to_optional_arg(arg, "--promisor", &promisor_msg)) {
				; /* already parsed */
			} else if (starts_with(arg, "--threads=")) {
				char *end;
				nr_threads = strtoul(arg+10, &end, 0);
				if (!arg[10] || *end || nr_threads < 0)
					usage(index_pack_usage);
				if (!HAVE_THREADS && nr_threads != 1) {
					warning(_("no threads support, ignoring %s"), arg);
					nr_threads = 1;
				}
			} else if (starts_with(arg, "--pack_header=")) {
				struct pack_header *hdr;
				char *c;

				hdr = (struct pack_header *)input_buffer;
				hdr->hdr_signature = htonl(PACK_SIGNATURE);
				hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
				if (*c != ',')
					die(_("bad %s"), arg);
				hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
				if (*c)
					die(_("bad %s"), arg);
				input_len = sizeof(*hdr);
			} else if (!strcmp(arg, "-v")) {
				verbose = 1;
			} else if (!strcmp(arg, "--show-resolving-progress")) {
				show_resolving_progress = 1;
			} else if (!strcmp(arg, "--report-end-of-input")) {
				report_end_of_input = 1;
			} else if (!strcmp(arg, "-o")) {
				if (index_name || (i+1) >= argc)
					usage(index_pack_usage);
				index_name = argv[++i];
			} else if (starts_with(arg, "--index-version=")) {
				char *c;
				opts.version = strtoul(arg + 16, &c, 10);
				if (opts.version > 2)
					die(_("bad %s"), arg);
				if (*c == ',')
					opts.off32_limit = strtoul(c+1, &c, 0);
				if (*c || opts.off32_limit & 0x80000000)
					die(_("bad %s"), arg);
			} else if (skip_prefix(arg, "--max-input-size=", &arg)) {
				max_input_size = strtoumax(arg, NULL, 10);
			} else
				usage(index_pack_usage);
			continue;
		}

		if (pack_name)
			usage(index_pack_usage);
		pack_name = arg;
	}

	if (!pack_name && !from_stdin)
		usage(index_pack_usage);
	if (fix_thin_pack && !from_stdin)
		die(_("--fix-thin cannot be used without --stdin"));
	if (from_stdin && !startup_info->have_repository)
		die(_("--stdin requires a git repository"));
	if (!index_name && pack_name)
		index_name = derive_filename(pack_name, "idx", &index_name_buf);

	if (verify) {
		if (!index_name)
			die(_("--verify with no packfile name given"));
		read_idx_option(&opts, index_name);
		opts.flags |= WRITE_IDX_VERIFY | WRITE_IDX_STRICT;
	}
	if (strict)
		opts.flags |= WRITE_IDX_STRICT;

	if (HAVE_THREADS && !nr_threads) {
		nr_threads = online_cpus();
		/* An experiment showed that more threads does not mean faster */
		if (nr_threads > 3)
			nr_threads = 3;
	}

	curr_pack = open_pack_file(pack_name);
	parse_pack_header();
	objects = xcalloc(st_add(nr_objects, 1), sizeof(struct object_entry));
	if (show_stat)
		obj_stat = xcalloc(st_add(nr_objects, 1), sizeof(struct object_stat));
	ofs_deltas = xcalloc(nr_objects, sizeof(struct ofs_delta_entry));
	parse_pack_objects(pack_hash);
	if (report_end_of_input)
		write_in_full(2, "\0", 1);
	resolve_deltas();
	conclude_pack(fix_thin_pack, curr_pack, pack_hash);
	free(ofs_deltas);
	free(ref_deltas);
	if (strict)
		foreign_nr = check_objects();

	if (show_stat)
		show_pack_info(stat_only);

	ALLOC_ARRAY(idx_objects, nr_objects);
	for (i = 0; i < nr_objects; i++)
		idx_objects[i] = &objects[i].idx;
	curr_index = write_idx_file(index_name, idx_objects, nr_objects, &opts, pack_hash);
	free(idx_objects);

	if (!verify)
		final(pack_name, curr_pack,
		      index_name, curr_index,
		      keep_msg, promisor_msg,
		      pack_hash);
	else
		close(input_fd);

	if (do_fsck_object && fsck_finish(&fsck_options))
		die(_("fsck error in pack objects"));

	free(objects);
	strbuf_release(&index_name_buf);
	if (pack_name == NULL)
		free((void *) curr_pack);
	if (index_name == NULL)
		free((void *) curr_index);

	/*
	 * Let the caller know this pack is not self contained
	 */
	if (check_self_contained_and_connected && foreign_nr)
		return 1;

	return 0;
}