summaryrefslogtreecommitdiff
path: root/builtin-pack-objects.c
blob: 50fc37fa0f77876fd73558eab3751653cce2a27e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
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
#include "builtin.h"
#include "cache.h"
#include "object.h"
#include "blob.h"
#include "commit.h"
#include "tag.h"
#include "tree.h"
#include "delta.h"
#include "pack.h"
#include "csum-file.h"
#include "tree-walk.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
 
static const char pack_usage[] = "\
git-pack-objects [{ -q | --progress | --all-progress }] \n\
	[--local] [--incremental] [--window=N] [--depth=N] \n\
	[--no-reuse-delta] [--delta-base-offset] [--non-empty] \n\
	[--revs [--unpacked | --all]*] [--reflog] [--stdout | base-name] \n\
	[<ref-list | <object-list]";
 
struct object_entry {
	unsigned char sha1[20];
	uint32_t crc32;		/* crc of raw pack data for this object */
	off_t offset;		/* offset into the final pack file */
	unsigned long size;	/* uncompressed size */
	unsigned int hash;	/* name hint hash */
	unsigned int depth;	/* delta depth */
	struct packed_git *in_pack; 	/* already in pack */
	off_t in_pack_offset;
	struct object_entry *delta;	/* delta base object */
	struct object_entry *delta_child; /* deltified objects who bases me */
	struct object_entry *delta_sibling; /* other deltified objects who
					     * uses the same base as me
					     */
	unsigned long delta_size;	/* delta data size (uncompressed) */
	enum object_type type;
	enum object_type in_pack_type;	/* could be delta */
	unsigned char in_pack_header_size;
	unsigned char preferred_base; /* we do not pack this, but is available
				       * to be used as the base objectto delta
				       * objects against.
				       */
};
 
/*
 * Objects we are going to pack are collected in objects array (dynamically
 * expanded).  nr_objects & nr_alloc controls this array.  They are stored
 * in the order we see -- typically rev-list --objects order that gives us
 * nice "minimum seek" order.
 */
static struct object_entry *objects;
static uint32_t nr_objects, nr_alloc, nr_result;
 
static int non_empty;
static int no_reuse_delta;
static int local;
static int incremental;
static int allow_ofs_delta;
static const char *pack_tmp_name, *idx_tmp_name;
static char tmpname[PATH_MAX];
static unsigned char pack_file_sha1[20];
static int progress = 1;
static volatile sig_atomic_t progress_update;
static int window = 10;
static int pack_to_stdout;
static int num_preferred_base;
 
/*
 * The object names in objects array are hashed with this hashtable,
 * to help looking up the entry by object name.
 * This hashtable is built after all the objects are seen.
 */
static int *object_ix;
static int object_ix_hashsz;
 
/*
 * Pack index for existing packs give us easy access to the offsets into
 * corresponding pack file where each object's data starts, but the entries
 * do not store the size of the compressed representation (uncompressed
 * size is easily available by examining the pack entry header).  It is
 * also rather expensive to find the sha1 for an object given its offset.
 *
 * We build a hashtable of existing packs (pack_revindex), and keep reverse
 * index here -- pack index file is sorted by object name mapping to offset;
 * this pack_revindex[].revindex array is a list of offset/index_nr pairs
 * ordered by offset, so if you know the offset of an object, next offset
 * is where its packed representation ends and the index_nr can be used to
 * get the object sha1 from the main index.
 */
struct revindex_entry {
	off_t offset;
	unsigned int nr;
};
struct pack_revindex {
	struct packed_git *p;
	struct revindex_entry *revindex;
};
static struct  pack_revindex *pack_revindex;
static int pack_revindex_hashsz;
 
/*
 * stats
 */
static uint32_t written, written_delta;
static uint32_t reused, reused_delta;
 
static int pack_revindex_ix(struct packed_git *p)
{
	unsigned long ui = (unsigned long)p;
	int i;
 
	ui = ui ^ (ui >> 16); /* defeat structure alignment */
	i = (int)(ui % pack_revindex_hashsz);
	while (pack_revindex[i].p) {
		if (pack_revindex[i].p == p)
			return i;
		if (++i == pack_revindex_hashsz)
			i = 0;
	}
	return -1 - i;
}
 
static void prepare_pack_ix(void)
{
	int num;
	struct packed_git *p;
	for (num = 0, p = packed_git; p; p = p->next)
		num++;
	if (!num)
		return;
	pack_revindex_hashsz = num * 11;
	pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
	for (p = packed_git; p; p = p->next) {
		num = pack_revindex_ix(p);
		num = - 1 - num;
		pack_revindex[num].p = p;
	}
	/* revindex elements are lazily initialized */
}
 
static int cmp_offset(const void *a_, const void *b_)
{
	const struct revindex_entry *a = a_;
	const struct revindex_entry *b = b_;
	return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
}
 
/*
 * Ordered list of offsets of objects in the pack.
 */
static void prepare_pack_revindex(struct pack_revindex *rix)
{
	struct packed_git *p = rix->p;
	int num_ent = p->num_objects;
	int i;
	const char *index = p->index_data;
 
	rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
	index += 4 * 256;
 
	if (p->index_version > 1) {
		const uint32_t *off_32 =
			(uint32_t *)(index + 8 + p->num_objects * (20 + 4));
		const uint32_t *off_64 = off_32 + p->num_objects;
		for (i = 0; i < num_ent; i++) {
			uint32_t off = ntohl(*off_32++);
			if (!(off & 0x80000000)) {
				rix->revindex[i].offset = off;
			} else {
				rix->revindex[i].offset =
					((uint64_t)ntohl(*off_64++)) << 32;
				rix->revindex[i].offset |=
					ntohl(*off_64++);
			}
			rix->revindex[i].nr = i;
		}
	} else {
		for (i = 0; i < num_ent; i++) {
			uint32_t hl = *((uint32_t *)(index + 24 * i));
			rix->revindex[i].offset = ntohl(hl);
			rix->revindex[i].nr = i;
		}
	}
 
	/* This knows the pack format -- the 20-byte trailer
	 * follows immediately after the last object data.
	 */
	rix->revindex[num_ent].offset = p->pack_size - 20;
	rix->revindex[num_ent].nr = -1;
	qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
}
 
static struct revindex_entry * find_packed_object(struct packed_git *p,
						  off_t ofs)
{
	int num;
	int lo, hi;
	struct pack_revindex *rix;
	struct revindex_entry *revindex;
	num = pack_revindex_ix(p);
	if (num < 0)
		die("internal error: pack revindex uninitialized");
	rix = &pack_revindex[num];
	if (!rix->revindex)
		prepare_pack_revindex(rix);
	revindex = rix->revindex;
	lo = 0;
	hi = p->num_objects + 1;
	do {
		int mi = (lo + hi) / 2;
		if (revindex[mi].offset == ofs) {
			return revindex + mi;
		}
		else if (ofs < revindex[mi].offset)
			hi = mi;
		else
			lo = mi + 1;
	} while (lo < hi);
	die("internal error: pack revindex corrupt");
}
 
static const unsigned char *find_packed_object_name(struct packed_git *p,
						    off_t ofs)
{
	struct revindex_entry *entry = find_packed_object(p, ofs);
	return nth_packed_object_sha1(p, entry->nr);
}
 
static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
{
	unsigned long othersize, delta_size;
	enum object_type type;
	void *otherbuf = read_sha1_file(entry->delta->sha1, &type, &othersize);
	void *delta_buf;
 
	if (!otherbuf)
		die("unable to read %s", sha1_to_hex(entry->delta->sha1));
        delta_buf = diff_delta(otherbuf, othersize,
			       buf, size, &delta_size, 0);
        if (!delta_buf || delta_size != entry->delta_size)
        	die("delta size changed");
        free(buf);
        free(otherbuf);
	return delta_buf;
}
 
/*
 * The per-object header is a pretty dense thing, which is
 *  - first byte: low four bits are "size", then three bits of "type",
 *    and the high bit is "size continues".
 *  - each byte afterwards: low seven bits are size continuation,
 *    with the high bit being "size continues"
 */
static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
{
	int n = 1;
	unsigned char c;
 
	if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
		die("bad type %d", type);
 
	c = (type << 4) | (size & 15);
	size >>= 4;
	while (size) {
		*hdr++ = c | 0x80;
		c = size & 0x7f;
		size >>= 7;
		n++;
	}
	*hdr = c;
	return n;
}
 
/*
 * we are going to reuse the existing object data as is.  make
 * sure it is not corrupt.
 */
static int check_pack_inflate(struct packed_git *p,
		struct pack_window **w_curs,
		off_t offset,
		off_t len,
		unsigned long expect)
{
	z_stream stream;
	unsigned char fakebuf[4096], *in;
	int st;
 
	memset(&stream, 0, sizeof(stream));
	inflateInit(&stream);
	do {
		in = use_pack(p, w_curs, offset, &stream.avail_in);
		stream.next_in = in;
		stream.next_out = fakebuf;
		stream.avail_out = sizeof(fakebuf);
		st = inflate(&stream, Z_FINISH);
		offset += stream.next_in - in;
	} while (st == Z_OK || st == Z_BUF_ERROR);
	inflateEnd(&stream);
	return (st == Z_STREAM_END &&
		stream.total_out == expect &&
		stream.total_in == len) ? 0 : -1;
}
 
static int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
			  off_t offset, off_t len, unsigned int nr)
{
	const uint32_t *index_crc;
	uint32_t data_crc = crc32(0, Z_NULL, 0);
 
	do {
		unsigned int avail;
		void *data = use_pack(p, w_curs, offset, &avail);
		if (avail > len)
			avail = len;
		data_crc = crc32(data_crc, data, avail);
		offset += avail;
		len -= avail;
	} while (len);
 
	index_crc = p->index_data;
	index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
 
	return data_crc != ntohl(*index_crc);
}
 
static void copy_pack_data(struct sha1file *f,
		struct packed_git *p,
		struct pack_window **w_curs,
		off_t offset,
		off_t len)
{
	unsigned char *in;
	unsigned int avail;
 
	while (len) {
		in = use_pack(p, w_curs, offset, &avail);
		if (avail > len)
			avail = (unsigned int)len;
		sha1write(f, in, avail);
		offset += avail;
		len -= avail;
	}
}
 
static int check_loose_inflate(unsigned char *data, unsigned long len, unsigned long expect)
{
	z_stream stream;
	unsigned char fakebuf[4096];
	int st;
 
	memset(&stream, 0, sizeof(stream));
	stream.next_in = data;
	stream.avail_in = len;
	stream.next_out = fakebuf;
	stream.avail_out = sizeof(fakebuf);
	inflateInit(&stream);
 
	while (1) {
		st = inflate(&stream, Z_FINISH);
		if (st == Z_STREAM_END || st == Z_OK) {
			st = (stream.total_out == expect &&
			      stream.total_in == len) ? 0 : -1;
			break;
		}
		if (st != Z_BUF_ERROR) {
			st = -1;
			break;
		}
		stream.next_out = fakebuf;
		stream.avail_out = sizeof(fakebuf);
	}
	inflateEnd(&stream);
	return st;
}
 
static int revalidate_loose_object(struct object_entry *entry,
				   unsigned char *map,
				   unsigned long mapsize)
{
	/* we already know this is a loose object with new type header. */
	enum object_type type;
	unsigned long size, used;
 
	if (pack_to_stdout)
		return 0;
 
	used = unpack_object_header_gently(map, mapsize, &type, &size);
	if (!used)
		return -1;
	map += used;
	mapsize -= used;
	return check_loose_inflate(map, mapsize, size);
}
 
static unsigned long write_object(struct sha1file *f,
				  struct object_entry *entry)
{
	unsigned long size;
	enum object_type type;
	void *buf;
	unsigned char header[10];
	unsigned hdrlen;
	off_t datalen;
	enum object_type obj_type;
	int to_reuse = 0;
 
	if (!pack_to_stdout)
		crc32_begin(f);
 
	obj_type = entry->type;
	if (! entry->in_pack)
		to_reuse = 0;	/* can't reuse what we don't have */
	else if (obj_type == OBJ_REF_DELTA || obj_type == OBJ_OFS_DELTA)
		to_reuse = 1;	/* check_object() decided it for us */
	else if (obj_type != entry->in_pack_type)
		to_reuse = 0;	/* pack has delta which is unusable */
	else if (entry->delta)
		to_reuse = 0;	/* we want to pack afresh */
	else
		to_reuse = 1;	/* we have it in-pack undeltified,
				 * and we do not need to deltify it.
				 */
 
	if (!entry->in_pack && !entry->delta) {
		unsigned char *map;
		unsigned long mapsize;
		map = map_sha1_file(entry->sha1, &mapsize);
		if (map && !legacy_loose_object(map)) {
			/* We can copy straight into the pack file */
			if (revalidate_loose_object(entry, map, mapsize))
				die("corrupt loose object %s",
				    sha1_to_hex(entry->sha1));
			sha1write(f, map, mapsize);
			munmap(map, mapsize);
			written++;
			reused++;
			return mapsize;
		}
		if (map)
			munmap(map, mapsize);
	}
 
	if (!to_reuse) {
		buf = read_sha1_file(entry->sha1, &type, &size);
		if (!buf)
			die("unable to read %s", sha1_to_hex(entry->sha1));
		if (size != entry->size)
			die("object %s size inconsistency (%lu vs %lu)",
			    sha1_to_hex(entry->sha1), size, entry->size);
		if (entry->delta) {
			buf = delta_against(buf, size, entry);
			size = entry->delta_size;
			obj_type = (allow_ofs_delta && entry->delta->offset) ?
				OBJ_OFS_DELTA : OBJ_REF_DELTA;
		}
		/*
		 * The object header is a byte of 'type' followed by zero or
		 * more bytes of length.
		 */
		hdrlen = encode_header(obj_type, size, header);
		sha1write(f, header, hdrlen);
 
		if (obj_type == OBJ_OFS_DELTA) {
			/*
			 * Deltas with relative base contain an additional
			 * encoding of the relative offset for the delta
			 * base from this object's position in the pack.
			 */
			off_t ofs = entry->offset - entry->delta->offset;
			unsigned pos = sizeof(header) - 1;
			header[pos] = ofs & 127;
			while (ofs >>= 7)
				header[--pos] = 128 | (--ofs & 127);
			sha1write(f, header + pos, sizeof(header) - pos);
			hdrlen += sizeof(header) - pos;
		} else if (obj_type == OBJ_REF_DELTA) {
			/*
			 * Deltas with a base reference contain
			 * an additional 20 bytes for the base sha1.
			 */
			sha1write(f, entry->delta->sha1, 20);
			hdrlen += 20;
		}
		datalen = sha1write_compressed(f, buf, size);
		free(buf);
	}
	else {
		struct packed_git *p = entry->in_pack;
		struct pack_window *w_curs = NULL;
		struct revindex_entry *revidx;
		off_t offset;
 
		if (entry->delta) {
			obj_type = (allow_ofs_delta && entry->delta->offset) ?
				OBJ_OFS_DELTA : OBJ_REF_DELTA;
			reused_delta++;
		}
		hdrlen = encode_header(obj_type, entry->size, header);
		sha1write(f, header, hdrlen);
		if (obj_type == OBJ_OFS_DELTA) {
			off_t ofs = entry->offset - entry->delta->offset;
			unsigned pos = sizeof(header) - 1;
			header[pos] = ofs & 127;
			while (ofs >>= 7)
				header[--pos] = 128 | (--ofs & 127);
			sha1write(f, header + pos, sizeof(header) - pos);
			hdrlen += sizeof(header) - pos;
		} else if (obj_type == OBJ_REF_DELTA) {
			sha1write(f, entry->delta->sha1, 20);
			hdrlen += 20;
		}
 
		offset = entry->in_pack_offset;
		revidx = find_packed_object(p, offset);
		datalen = revidx[1].offset - offset;
		if (!pack_to_stdout && p->index_version > 1 &&
		    check_pack_crc(p, &w_curs, offset, datalen, revidx->nr))
			die("bad packed object CRC for %s", sha1_to_hex(entry->sha1));
		offset += entry->in_pack_header_size;
		datalen -= entry->in_pack_header_size;
		if (!pack_to_stdout && p->index_version == 1 &&
		    check_pack_inflate(p, &w_curs, offset, datalen, entry->size))
			die("corrupt packed object for %s", sha1_to_hex(entry->sha1));
		copy_pack_data(f, p, &w_curs, offset, datalen);
		unuse_pack(&w_curs);
		reused++;
	}
	if (entry->delta)
		written_delta++;
	written++;
	if (!pack_to_stdout)
		entry->crc32 = crc32_end(f);
	return hdrlen + datalen;
}
 
static off_t write_one(struct sha1file *f,
			       struct object_entry *e,
			       off_t offset)
{
	unsigned long size;
 
	/* offset is non zero if object is written already. */
	if (e->offset || e->preferred_base)
		return offset;
 
	/* if we are deltified, write out base object first. */
	if (e->delta)
		offset = write_one(f, e->delta, offset);
 
	e->offset = offset;
	size = write_object(f, e);
 
	/* make sure off_t is sufficiently large not to wrap */
	if (offset > offset + size)
		die("pack too large for current definition of off_t");
	return offset + size;
}
 
static off_t write_pack_file(void)
{
	uint32_t i;
	struct sha1file *f;
	off_t offset, last_obj_offset = 0;
	struct pack_header hdr;
	unsigned last_percent = 999;
	int do_progress = progress;
 
	if (pack_to_stdout) {
		f = sha1fd(1, "<stdout>");
		do_progress >>= 1;
	} else {
		int fd;
		snprintf(tmpname, sizeof(tmpname), "tmp_pack_XXXXXX");
		fd = mkstemp(tmpname);
		if (fd < 0)
			die("unable to create %s: %s\n", tmpname, strerror(errno));
		pack_tmp_name = xstrdup(tmpname);
		f = sha1fd(fd, pack_tmp_name);
	}
 
	if (do_progress)
		fprintf(stderr, "Writing %u objects.\n", nr_result);
 
	hdr.hdr_signature = htonl(PACK_SIGNATURE);
	hdr.hdr_version = htonl(PACK_VERSION);
	hdr.hdr_entries = htonl(nr_result);
	sha1write(f, &hdr, sizeof(hdr));
	offset = sizeof(hdr);
	if (!nr_result)
		goto done;
	for (i = 0; i < nr_objects; i++) {
		last_obj_offset = offset;
		offset = write_one(f, objects + i, offset);
		if (do_progress) {
			unsigned percent = written * 100 / nr_result;
			if (progress_update || percent != last_percent) {
				fprintf(stderr, "%4u%% (%u/%u) done\r",
					percent, written, nr_result);
				progress_update = 0;
				last_percent = percent;
			}
		}
	}
	if (do_progress)
		fputc('\n', stderr);
 done:
	if (written != nr_result)
		die("wrote %u objects while expecting %u", written, nr_result);
	sha1close(f, pack_file_sha1, 1);
 
	return last_obj_offset;
}
 
static int sha1_sort(const void *_a, const void *_b)
{
	const struct object_entry *a = *(struct object_entry **)_a;
	const struct object_entry *b = *(struct object_entry **)_b;
	return hashcmp(a->sha1, b->sha1);
}
 
static uint32_t index_default_version = 1;
static uint32_t index_off32_limit = 0x7fffffff;
 
static void write_index_file(off_t last_obj_offset, unsigned char *sha1)
{
	struct sha1file *f;
	struct object_entry **sorted_by_sha, **list, **last;
	uint32_t array[256];
	uint32_t i, index_version;
	SHA_CTX ctx;
	int fd;
 
	snprintf(tmpname, sizeof(tmpname), "tmp_idx_XXXXXX");
	fd = mkstemp(tmpname);
	if (fd < 0)
		die("unable to create %s: %s\n", tmpname, strerror(errno));
	idx_tmp_name = xstrdup(tmpname);
	f = sha1fd(fd, idx_tmp_name);
 
	if (nr_result) {
		uint32_t j = 0;
		sorted_by_sha =
			xcalloc(nr_result, sizeof(struct object_entry *));
		for (i = 0; i < nr_objects; i++)
			if (!objects[i].preferred_base)
				sorted_by_sha[j++] = objects + i;
		if (j != nr_result)
			die("listed %u objects while expecting %u", j, nr_result);
		qsort(sorted_by_sha, nr_result, sizeof(*sorted_by_sha), sha1_sort);
		list = sorted_by_sha;
		last = sorted_by_sha + nr_result;
	} else
		sorted_by_sha = list = last = NULL;
 
	/* if last object's offset is >= 2^31 we should use index V2 */
	index_version = (last_obj_offset >> 31) ? 2 : index_default_version;
 
	/* index versions 2 and above need a header */
	if (index_version >= 2) {
		struct pack_idx_header hdr;
		hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
		hdr.idx_version = htonl(index_version);
		sha1write(f, &hdr, sizeof(hdr));
	}
 
	/*
	 * Write the first-level table (the list is sorted,
	 * but we use a 256-entry lookup to be able to avoid
	 * having to do eight extra binary search iterations).
	 */
	for (i = 0; i < 256; i++) {
		struct object_entry **next = list;
		while (next < last) {
			struct object_entry *entry = *next;
			if (entry->sha1[0] != i)
				break;
			next++;
		}
		array[i] = htonl(next - sorted_by_sha);
		list = next;
	}
	sha1write(f, array, 256 * 4);
 
	/* Compute the SHA1 hash of sorted object names. */
	SHA1_Init(&ctx);
 
	/* Write the actual SHA1 entries. */
	list = sorted_by_sha;
	for (i = 0; i < nr_result; i++) {
		struct object_entry *entry = *list++;
		if (index_version < 2) {
			uint32_t offset = htonl(entry->offset);
			sha1write(f, &offset, 4);
		}
		sha1write(f, entry->sha1, 20);
		SHA1_Update(&ctx, entry->sha1, 20);
	}
 
	if (index_version >= 2) {
		unsigned int nr_large_offset = 0;
 
		/* write the crc32 table */
		list = sorted_by_sha;
		for (i = 0; i < nr_objects; i++) {
			struct object_entry *entry = *list++;
			uint32_t crc32_val = htonl(entry->crc32);
			sha1write(f, &crc32_val, 4);
		}
 
		/* write the 32-bit offset table */
		list = sorted_by_sha;
		for (i = 0; i < nr_objects; i++) {
			struct object_entry *entry = *list++;
			uint32_t offset = (entry->offset <= index_off32_limit) ?
				entry->offset : (0x80000000 | nr_large_offset++);
			offset = htonl(offset);
			sha1write(f, &offset, 4);
		}
 
		/* write the large offset table */
		list = sorted_by_sha;
		while (nr_large_offset) {
			struct object_entry *entry = *list++;
			uint64_t offset = entry->offset;
			if (offset > index_off32_limit) {
				uint32_t split[2];
				split[0]        = htonl(offset >> 32);
				split[1] = htonl(offset & 0xffffffff);
				sha1write(f, split, 8);
				nr_large_offset--;
			}
		}
	}
 
	sha1write(f, pack_file_sha1, 20);
	sha1close(f, NULL, 1);
	free(sorted_by_sha);
	SHA1_Final(sha1, &ctx);
}
 
static int locate_object_entry_hash(const unsigned char *sha1)
{
	int i;
	unsigned int ui;
	memcpy(&ui, sha1, sizeof(unsigned int));
	i = ui % object_ix_hashsz;
	while (0 < object_ix[i]) {
		if (!hashcmp(sha1, objects[object_ix[i] - 1].sha1))
			return i;
		if (++i == object_ix_hashsz)
			i = 0;
	}
	return -1 - i;
}
 
static struct object_entry *locate_object_entry(const unsigned char *sha1)
{
	int i;
 
	if (!object_ix_hashsz)
		return NULL;
 
	i = locate_object_entry_hash(sha1);
	if (0 <= i)
		return &objects[object_ix[i]-1];
	return NULL;
}
 
static void rehash_objects(void)
{
	uint32_t i;
	struct object_entry *oe;
 
	object_ix_hashsz = nr_objects * 3;
	if (object_ix_hashsz < 1024)
		object_ix_hashsz = 1024;
	object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
	memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
	for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
		int ix = locate_object_entry_hash(oe->sha1);
		if (0 <= ix)
			continue;
		ix = -1 - ix;
		object_ix[ix] = i + 1;
	}
}
 
static unsigned name_hash(const char *name)
{
	unsigned char c;
	unsigned hash = 0;
 
	/*
	 * This effectively just creates a sortable number from the
	 * last sixteen non-whitespace characters. Last characters
	 * count "most", so things that end in ".c" sort together.
	 */
	while ((c = *name++) != 0) {
		if (isspace(c))
			continue;
		hash = (hash >> 2) + (c << 24);
	}
	return hash;
}
 
static int add_object_entry(const unsigned char *sha1, enum object_type type,
			    unsigned hash, int exclude)
{
	struct object_entry *entry;
	struct packed_git *p, *found_pack = NULL;
	off_t found_offset = 0;
	int ix;
 
	ix = nr_objects ? locate_object_entry_hash(sha1) : -1;
	if (ix >= 0) {
		if (exclude) {
			entry = objects + object_ix[ix] - 1;
			if (!entry->preferred_base)
				nr_result--;
			entry->preferred_base = 1;
		}
		return 0;
	}
 
	for (p = packed_git; p; p = p->next) {
		off_t offset = find_pack_entry_one(sha1, p);
		if (offset) {
			if (!found_pack) {
				found_offset = offset;
				found_pack = p;
			}
			if (exclude)
				break;
			if (incremental)
				return 0;
			if (local && !p->pack_local)
				return 0;
		}
	}
 
	if (nr_objects >= nr_alloc) {
		nr_alloc = (nr_alloc  + 1024) * 3 / 2;
		objects = xrealloc(objects, nr_alloc * sizeof(*entry));
	}
 
	entry = objects + nr_objects++;
	memset(entry, 0, sizeof(*entry));
	hashcpy(entry->sha1, sha1);
	entry->hash = hash;
	if (type)
		entry->type = type;
	if (exclude)
		entry->preferred_base = 1;
	else
		nr_result++;
	if (found_pack) {
		entry->in_pack = found_pack;
		entry->in_pack_offset = found_offset;
	}
 
	if (object_ix_hashsz * 3 <= nr_objects * 4)
		rehash_objects();
	else
		object_ix[-1 - ix] = nr_objects;
 
	if (progress_update) {
		fprintf(stderr, "Counting objects...%u\r", nr_objects);
		progress_update = 0;
	}
 
	return 1;
}
 
struct pbase_tree_cache {
	unsigned char sha1[20];
	int ref;
	int temporary;
	void *tree_data;
	unsigned long tree_size;
};
 
static struct pbase_tree_cache *(pbase_tree_cache[256]);
static int pbase_tree_cache_ix(const unsigned char *sha1)
{
	return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
}
static int pbase_tree_cache_ix_incr(int ix)
{
	return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
}
 
static struct pbase_tree {
	struct pbase_tree *next;
	/* This is a phony "cache" entry; we are not
	 * going to evict it nor find it through _get()
	 * mechanism -- this is for the toplevel node that
	 * would almost always change with any commit.
	 */
	struct pbase_tree_cache pcache;
} *pbase_tree;
 
static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
{
	struct pbase_tree_cache *ent, *nent;
	void *data;
	unsigned long size;
	enum object_type type;
	int neigh;
	int my_ix = pbase_tree_cache_ix(sha1);
	int available_ix = -1;
 
	/* pbase-tree-cache acts as a limited hashtable.
	 * your object will be found at your index or within a few
	 * slots after that slot if it is cached.
	 */
	for (neigh = 0; neigh < 8; neigh++) {
		ent = pbase_tree_cache[my_ix];
		if (ent && !hashcmp(ent->sha1, sha1)) {
			ent->ref++;
			return ent;
		}
		else if (((available_ix < 0) && (!ent || !ent->ref)) ||
			 ((0 <= available_ix) &&
			  (!ent && pbase_tree_cache[available_ix])))
			available_ix = my_ix;
		if (!ent)
			break;
		my_ix = pbase_tree_cache_ix_incr(my_ix);
	}
 
	/* Did not find one.  Either we got a bogus request or
	 * we need to read and perhaps cache.
	 */
	data = read_sha1_file(sha1, &type, &size);
	if (!data)
		return NULL;
	if (type != OBJ_TREE) {
		free(data);
		return NULL;
	}
 
	/* We need to either cache or return a throwaway copy */
 
	if (available_ix < 0)
		ent = NULL;
	else {
		ent = pbase_tree_cache[available_ix];
		my_ix = available_ix;
	}
 
	if (!ent) {
		nent = xmalloc(sizeof(*nent));
		nent->temporary = (available_ix < 0);
	}
	else {
		/* evict and reuse */
		free(ent->tree_data);
		nent = ent;
	}
	hashcpy(nent->sha1, sha1);
	nent->tree_data = data;
	nent->tree_size = size;
	nent->ref = 1;
	if (!nent->temporary)
		pbase_tree_cache[my_ix] = nent;
	return nent;
}
 
static void pbase_tree_put(struct pbase_tree_cache *cache)
{
	if (!cache->temporary) {
		cache->ref--;
		return;
	}
	free(cache->tree_data);
	free(cache);
}
 
static int name_cmp_len(const char *name)
{
	int i;
	for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
		;
	return i;
}
 
static void add_pbase_object(struct tree_desc *tree,
			     const char *name,
			     int cmplen,
			     const char *fullname)
{
	struct name_entry entry;
	int cmp;
 
	while (tree_entry(tree,&entry)) {
		cmp = tree_entry_len(entry.path, entry.sha1) != cmplen ? 1 :
		      memcmp(name, entry.path, cmplen);
		if (cmp > 0)
			continue;
		if (cmp < 0)
			return;
		if (name[cmplen] != '/') {
			unsigned hash = name_hash(fullname);
			add_object_entry(entry.sha1,
					 S_ISDIR(entry.mode) ? OBJ_TREE : OBJ_BLOB,
					 hash, 1);
			return;
		}
		if (S_ISDIR(entry.mode)) {
			struct tree_desc sub;
			struct pbase_tree_cache *tree;
			const char *down = name+cmplen+1;
			int downlen = name_cmp_len(down);
 
			tree = pbase_tree_get(entry.sha1);
			if (!tree)
				return;
			init_tree_desc(&sub, tree->tree_data, tree->tree_size);
 
			add_pbase_object(&sub, down, downlen, fullname);
			pbase_tree_put(tree);
		}
	}
}
 
static unsigned *done_pbase_paths;
static int done_pbase_paths_num;
static int done_pbase_paths_alloc;
static int done_pbase_path_pos(unsigned hash)
{
	int lo = 0;
	int hi = done_pbase_paths_num;
	while (lo < hi) {
		int mi = (hi + lo) / 2;
		if (done_pbase_paths[mi] == hash)
			return mi;
		if (done_pbase_paths[mi] < hash)
			hi = mi;
		else
			lo = mi + 1;
	}
	return -lo-1;
}
 
static int check_pbase_path(unsigned hash)
{
	int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
	if (0 <= pos)
		return 1;
	pos = -pos - 1;
	if (done_pbase_paths_alloc <= done_pbase_paths_num) {
		done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
		done_pbase_paths = xrealloc(done_pbase_paths,
					    done_pbase_paths_alloc *
					    sizeof(unsigned));
	}
	done_pbase_paths_num++;
	if (pos < done_pbase_paths_num)
		memmove(done_pbase_paths + pos + 1,
			done_pbase_paths + pos,
			(done_pbase_paths_num - pos - 1) * sizeof(unsigned));
	done_pbase_paths[pos] = hash;
	return 0;
}
 
static void add_preferred_base_object(const char *name, unsigned hash)
{
	struct pbase_tree *it;
	int cmplen;
 
	if (!num_preferred_base || check_pbase_path(hash))
		return;
 
	cmplen = name_cmp_len(name);
	for (it = pbase_tree; it; it = it->next) {
		if (cmplen == 0) {
			add_object_entry(it->pcache.sha1, OBJ_TREE, 0, 1);
		}
		else {
			struct tree_desc tree;
			init_tree_desc(&tree, it->pcache.tree_data, it->pcache.tree_size);
			add_pbase_object(&tree, name, cmplen, name);
		}
	}
}
 
static void add_preferred_base(unsigned char *sha1)
{
	struct pbase_tree *it;
	void *data;
	unsigned long size;
	unsigned char tree_sha1[20];
 
	if (window <= num_preferred_base++)
		return;
 
	data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
	if (!data)
		return;
 
	for (it = pbase_tree; it; it = it->next) {
		if (!hashcmp(it->pcache.sha1, tree_sha1)) {
			free(data);
			return;
		}
	}
 
	it = xcalloc(1, sizeof(*it));
	it->next = pbase_tree;
	pbase_tree = it;
 
	hashcpy(it->pcache.sha1, tree_sha1);
	it->pcache.tree_data = data;
	it->pcache.tree_size = size;
}
 
static void check_object(struct object_entry *entry)
{
	if (entry->in_pack) {
		struct packed_git *p = entry->in_pack;
		struct pack_window *w_curs = NULL;
		const unsigned char *base_ref = NULL;
		struct object_entry *base_entry;
		unsigned long used, used_0;
		unsigned int avail;
		off_t ofs;
		unsigned char *buf, c;
 
		buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);
 
		/*
		 * We want in_pack_type even if we do not reuse delta.
		 * There is no point not reusing non-delta representations.
		 */
		used = unpack_object_header_gently(buf, avail,
						   &entry->in_pack_type,
						   &entry->size);
 
		/*
		 * Determine if this is a delta and if so whether we can
		 * reuse it or not.  Otherwise let's find out as cheaply as
		 * possible what the actual type and size for this object is.
		 */
		switch (entry->in_pack_type) {
		default:
			/* Not a delta hence we've already got all we need. */
			entry->type = entry->in_pack_type;
			entry->in_pack_header_size = used;
			unuse_pack(&w_curs);
			return;
		case OBJ_REF_DELTA:
			if (!no_reuse_delta && !entry->preferred_base)
				base_ref = use_pack(p, &w_curs,
						entry->in_pack_offset + used, NULL);
			entry->in_pack_header_size = used + 20;
			break;
		case OBJ_OFS_DELTA:
			buf = use_pack(p, &w_curs,
				       entry->in_pack_offset + used, NULL);
			used_0 = 0;
			c = buf[used_0++];
			ofs = c & 127;
			while (c & 128) {
				ofs += 1;
				if (!ofs || MSB(ofs, 7))
					die("delta base offset overflow in pack for %s",
					    sha1_to_hex(entry->sha1));
				c = buf[used_0++];
				ofs = (ofs << 7) + (c & 127);
			}
			if (ofs >= entry->in_pack_offset)
				die("delta base offset out of bound for %s",
				    sha1_to_hex(entry->sha1));
			ofs = entry->in_pack_offset - ofs;
			if (!no_reuse_delta && !entry->preferred_base)
				base_ref = find_packed_object_name(p, ofs);
			entry->in_pack_header_size = used + used_0;
			break;
		}
 
		if (base_ref && (base_entry = locate_object_entry(base_ref))) {
			/*
			 * If base_ref was set above that means we wish to
			 * reuse delta data, and we even found that base
			 * in the list of objects we want to pack. Goodie!
			 *
			 * Depth value does not matter - find_deltas() will
			 * never consider reused delta as the base object to
			 * deltify other objects against, in order to avoid
			 * circular deltas.
			 */
			entry->type = entry->in_pack_type;
			entry->delta = base_entry;
			entry->delta_sibling = base_entry->delta_child;
			base_entry->delta_child = entry;
			unuse_pack(&w_curs);
			return;
		}
 
		if (entry->type) {
			/*
			 * This must be a delta and we already know what the
			 * final object type is.  Let's extract the actual
			 * object size from the delta header.
			 */
			entry->size = get_size_from_delta(p, &w_curs,
					entry->in_pack_offset + entry->in_pack_header_size);
			unuse_pack(&w_curs);
			return;
		}
 
		/*
		 * No choice but to fall back to the recursive delta walk
		 * with sha1_object_info() to find about the object type
		 * at this point...
		 */
		unuse_pack(&w_curs);
	}
 
	entry->type = sha1_object_info(entry->sha1, &entry->size);
	if (entry->type < 0)
		die("unable to get type of object %s",
		    sha1_to_hex(entry->sha1));
}
 
static int pack_offset_sort(const void *_a, const void *_b)
{
	const struct object_entry *a = *(struct object_entry **)_a;
	const struct object_entry *b = *(struct object_entry **)_b;
 
	/* avoid filesystem trashing with loose objects */
	if (!a->in_pack && !b->in_pack)
		return hashcmp(a->sha1, b->sha1);
 
	if (a->in_pack < b->in_pack)
		return -1;
	if (a->in_pack > b->in_pack)
		return 1;
	return a->in_pack_offset < b->in_pack_offset ? -1 :
			(a->in_pack_offset > b->in_pack_offset);
}
 
static void get_object_details(void)
{
	uint32_t i;
	struct object_entry **sorted_by_offset;
 
	sorted_by_offset = xcalloc(nr_objects, sizeof(struct object_entry *));
	for (i = 0; i < nr_objects; i++)
		sorted_by_offset[i] = objects + i;
	qsort(sorted_by_offset, nr_objects, sizeof(*sorted_by_offset), pack_offset_sort);
 
	prepare_pack_ix();
	for (i = 0; i < nr_objects; i++)
		check_object(sorted_by_offset[i]);
	free(sorted_by_offset);
}
 
static int type_size_sort(const void *_a, const void *_b)
{
	const struct object_entry *a = *(struct object_entry **)_a;
	const struct object_entry *b = *(struct object_entry **)_b;
 
	if (a->type < b->type)
		return -1;
	if (a->type > b->type)
		return 1;
	if (a->hash < b->hash)
		return -1;
	if (a->hash > b->hash)
		return 1;
	if (a->preferred_base < b->preferred_base)
		return -1;
	if (a->preferred_base > b->preferred_base)
		return 1;
	if (a->size < b->size)
		return -1;
	if (a->size > b->size)
		return 1;
	return a > b ? -1 : (a < b);  /* newest last */
}
 
struct unpacked {
	struct object_entry *entry;
	void *data;
	struct delta_index *index;
};
 
/*
 * We search for deltas _backwards_ in a list sorted by type and
 * by size, so that we see progressively smaller and smaller files.
 * That's because we prefer deltas to be from the bigger file
 * to the smaller - deletes are potentially cheaper, but perhaps
 * more importantly, the bigger file is likely the more recent
 * one.
 */
static int try_delta(struct unpacked *trg, struct unpacked *src,
		     unsigned max_depth)
{
	struct object_entry *trg_entry = trg->entry;
	struct object_entry *src_entry = src->entry;
	unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
	enum object_type type;
	void *delta_buf;
 
	/* Don't bother doing diffs between different types */
	if (trg_entry->type != src_entry->type)
		return -1;
 
	/* We do not compute delta to *create* objects we are not
	 * going to pack.
	 */
	if (trg_entry->preferred_base)
		return -1;
 
	/*
	 * We do not bother to try a delta that we discarded
	 * on an earlier try, but only when reusing delta data.
	 */
	if (!no_reuse_delta && trg_entry->in_pack &&
	    trg_entry->in_pack == src_entry->in_pack &&
	    trg_entry->in_pack_type != OBJ_REF_DELTA &&
	    trg_entry->in_pack_type != OBJ_OFS_DELTA)
		return 0;
 
	/* Let's not bust the allowed depth. */
	if (src_entry->depth >= max_depth)
		return 0;
 
	/* Now some size filtering heuristics. */
	trg_size = trg_entry->size;
	max_size = trg_size/2 - 20;
	max_size = max_size * (max_depth - src_entry->depth) / max_depth;
	if (max_size == 0)
		return 0;
	if (trg_entry->delta && trg_entry->delta_size <= max_size)
		max_size = trg_entry->delta_size-1;
	src_size = src_entry->size;
	sizediff = src_size < trg_size ? trg_size - src_size : 0;
	if (sizediff >= max_size)
		return 0;
 
	/* Load data if not already done */
	if (!trg->data) {
		trg->data = read_sha1_file(trg_entry->sha1, &type, &sz);
		if (sz != trg_size)
			die("object %s inconsistent object length (%lu vs %lu)",
			    sha1_to_hex(trg_entry->sha1), sz, trg_size);
	}
	if (!src->data) {
		src->data = read_sha1_file(src_entry->sha1, &type, &sz);
		if (sz != src_size)
			die("object %s inconsistent object length (%lu vs %lu)",
			    sha1_to_hex(src_entry->sha1), sz, src_size);
	}
	if (!src->index) {
		src->index = create_delta_index(src->data, src_size);
		if (!src->index)
			die("out of memory");
	}
 
	delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
	if (!delta_buf)
		return 0;
 
	trg_entry->delta = src_entry;
	trg_entry->delta_size = delta_size;
	trg_entry->depth = src_entry->depth + 1;
	free(delta_buf);
	return 1;
}
 
static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
{
	struct object_entry *child = me->delta_child;
	unsigned int m = n;
	while (child) {
		unsigned int c = check_delta_limit(child, n + 1);
		if (m < c)
			m = c;
		child = child->delta_sibling;
	}
	return m;
}
 
static void find_deltas(struct object_entry **list, int window, int depth)
{
	uint32_t i = nr_objects, idx = 0, processed = 0;
	unsigned int array_size = window * sizeof(struct unpacked);
	struct unpacked *array;
	unsigned last_percent = 999;
	int max_depth;
 
	if (!nr_objects)
		return;
	array = xmalloc(array_size);
	memset(array, 0, array_size);
	if (progress)
		fprintf(stderr, "Deltifying %u objects.\n", nr_result);
 
	do {
		struct object_entry *entry = list[--i];
		struct unpacked *n = array + idx;
		int j;
 
		if (!entry->preferred_base)
			processed++;
 
		if (progress) {
			unsigned percent = processed * 100 / nr_result;
			if (percent != last_percent || progress_update) {
				fprintf(stderr, "%4u%% (%u/%u) done\r",
					percent, processed, nr_result);
				progress_update = 0;
				last_percent = percent;
			}
		}
 
		if (entry->delta)
			/* This happens if we decided to reuse existing
			 * delta from a pack.  "!no_reuse_delta &&" is implied.
			 */
			continue;
 
		if (entry->size < 50)
			continue;
		free_delta_index(n->index);
		n->index = NULL;
		free(n->data);
		n->data = NULL;
		n->entry = entry;
 
		/*
		 * If the current object is at pack edge, take the depth the
		 * objects that depend on the current object into account
		 * otherwise they would become too deep.
		 */
		max_depth = depth;
		if (entry->delta_child) {
			max_depth -= check_delta_limit(entry, 0);
			if (max_depth <= 0)
				goto next;
		}
 
		j = window;
		while (--j > 0) {
			uint32_t other_idx = idx + j;
			struct unpacked *m;
			if (other_idx >= window)
				other_idx -= window;
			m = array + other_idx;
			if (!m->entry)
				break;
			if (try_delta(n, m, max_depth) < 0)
				break;
		}
 
		/* if we made n a delta, and if n is already at max
		 * depth, leaving it in the window is pointless.  we
		 * should evict it first.
		 */
		if (entry->delta && depth <= entry->depth)
			continue;
 
		next:
		idx++;
		if (idx >= window)
			idx = 0;
	} while (i > 0);
 
	if (progress)
		fputc('\n', stderr);
 
	for (i = 0; i < window; ++i) {
		free_delta_index(array[i].index);
		free(array[i].data);
	}
	free(array);
}
 
static void prepare_pack(int window, int depth)
{
	struct object_entry **delta_list;
	uint32_t i;
 
	get_object_details();
 
	if (!window || !depth)
		return;
 
	delta_list = xmalloc(nr_objects * sizeof(*delta_list));
	for (i = 0; i < nr_objects; i++)
		delta_list[i] = objects + i;
	qsort(delta_list, nr_objects, sizeof(*delta_list), type_size_sort);
	find_deltas(delta_list, window+1, depth);
	free(delta_list);
}
 
static void progress_interval(int signum)
{
	progress_update = 1;
}
 
static void setup_progress_signal(void)
{
	struct sigaction sa;
	struct itimerval v;
 
	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = progress_interval;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = SA_RESTART;
	sigaction(SIGALRM, &sa, NULL);
 
	v.it_interval.tv_sec = 1;
	v.it_interval.tv_usec = 0;
	v.it_value = v.it_interval;
	setitimer(ITIMER_REAL, &v, NULL);
}
 
static int git_pack_config(const char *k, const char *v)
{
	if(!strcmp(k, "pack.window")) {
		window = git_config_int(k, v);
		return 0;
	}
	return git_default_config(k, v);
}
 
static void read_object_list_from_stdin(void)
{
	char line[40 + 1 + PATH_MAX + 2];
	unsigned char sha1[20];
	unsigned hash;
 
	for (;;) {
		if (!fgets(line, sizeof(line), stdin)) {
			if (feof(stdin))
				break;
			if (!ferror(stdin))
				die("fgets returned NULL, not EOF, not error!");
			if (errno != EINTR)
				die("fgets: %s", strerror(errno));
			clearerr(stdin);
			continue;
		}
		if (line[0] == '-') {
			if (get_sha1_hex(line+1, sha1))
				die("expected edge sha1, got garbage:\n %s",
				    line);
			add_preferred_base(sha1);
			continue;
		}
		if (get_sha1_hex(line, sha1))
			die("expected sha1, got garbage:\n %s", line);
 
		hash = name_hash(line+41);
		add_preferred_base_object(line+41, hash);
		add_object_entry(sha1, 0, hash, 0);
	}
}
 
static void show_commit(struct commit *commit)
{
	add_object_entry(commit->object.sha1, OBJ_COMMIT, 0, 0);
}
 
static void show_object(struct object_array_entry *p)
{
	unsigned hash = name_hash(p->name);
	add_preferred_base_object(p->name, hash);
	add_object_entry(p->item->sha1, p->item->type, hash, 0);
}
 
static void show_edge(struct commit *commit)
{
	add_preferred_base(commit->object.sha1);
}
 
static void get_object_list(int ac, const char **av)
{
	struct rev_info revs;
	char line[1000];
	int flags = 0;
 
	init_revisions(&revs, NULL);
	save_commit_buffer = 0;
	track_object_refs = 0;
	setup_revisions(ac, av, &revs, NULL);
 
	while (fgets(line, sizeof(line), stdin) != NULL) {
		int len = strlen(line);
		if (line[len - 1] == '\n')
			line[--len] = 0;
		if (!len)
			break;
		if (*line == '-') {
			if (!strcmp(line, "--not")) {
				flags ^= UNINTERESTING;
				continue;
			}
			die("not a rev '%s'", line);
		}
		if (handle_revision_arg(line, &revs, flags, 1))
			die("bad revision '%s'", line);
	}
 
	prepare_revision_walk(&revs);
	mark_edges_uninteresting(revs.commits, &revs, show_edge);
	traverse_commit_list(&revs, show_commit, show_object);
}
 
static int adjust_perm(const char *path, mode_t mode)
{
	if (chmod(path, mode))
		return -1;
	return adjust_shared_perm(path);
}
 
int cmd_pack_objects(int argc, const char **argv, const char *prefix)
{
	int depth = 10;
	int use_internal_rev_list = 0;
	int thin = 0;
	uint32_t i;
	off_t last_obj_offset;
	const char *base_name = NULL;
	const char **rp_av;
	int rp_ac_alloc = 64;
	int rp_ac;
 
	rp_av = xcalloc(rp_ac_alloc, sizeof(*rp_av));
 
	rp_av[0] = "pack-objects";
	rp_av[1] = "--objects"; /* --thin will make it --objects-edge */
	rp_ac = 2;
 
	git_config(git_pack_config);
 
	progress = isatty(2);
	for (i = 1; i < argc; i++) {
		const char *arg = argv[i];
 
		if (*arg != '-')
			break;
 
		if (!strcmp("--non-empty", arg)) {
			non_empty = 1;
			continue;
		}
		if (!strcmp("--local", arg)) {
			local = 1;
			continue;
		}
		if (!strcmp("--incremental", arg)) {
			incremental = 1;
			continue;
		}
		if (!prefixcmp(arg, "--window=")) {
			char *end;
			window = strtoul(arg+9, &end, 0);
			if (!arg[9] || *end)
				usage(pack_usage);
			continue;
		}
		if (!prefixcmp(arg, "--depth=")) {
			char *end;
			depth = strtoul(arg+8, &end, 0);
			if (!arg[8] || *end)
				usage(pack_usage);
			continue;
		}
		if (!strcmp("--progress", arg)) {
			progress = 1;
			continue;
		}
		if (!strcmp("--all-progress", arg)) {
			progress = 2;
			continue;
		}
		if (!strcmp("-q", arg)) {
			progress = 0;
			continue;
		}
		if (!strcmp("--no-reuse-delta", arg)) {
			no_reuse_delta = 1;
			continue;
		}
		if (!strcmp("--delta-base-offset", arg)) {
			allow_ofs_delta = 1;
			continue;
		}
		if (!strcmp("--stdout", arg)) {
			pack_to_stdout = 1;
			continue;
		}
		if (!strcmp("--revs", arg)) {
			use_internal_rev_list = 1;
			continue;
		}
		if (!strcmp("--unpacked", arg) ||
		    !prefixcmp(arg, "--unpacked=") ||
		    !strcmp("--reflog", arg) ||
		    !strcmp("--all", arg)) {
			use_internal_rev_list = 1;
			if (rp_ac >= rp_ac_alloc - 1) {
				rp_ac_alloc = alloc_nr(rp_ac_alloc);
				rp_av = xrealloc(rp_av,
						 rp_ac_alloc * sizeof(*rp_av));
			}
			rp_av[rp_ac++] = arg;
			continue;
		}
		if (!strcmp("--thin", arg)) {
			use_internal_rev_list = 1;
			thin = 1;
			rp_av[1] = "--objects-edge";
			continue;
		}
		if (!prefixcmp(arg, "--index-version=")) {
			char *c;
			index_default_version = strtoul(arg + 16, &c, 10);
			if (index_default_version > 2)
				die("bad %s", arg);
			if (*c == ',')
				index_off32_limit = strtoul(c+1, &c, 0);
			if (*c || index_off32_limit & 0x80000000)
				die("bad %s", arg);
			continue;
		}
		usage(pack_usage);
	}
 
	/* Traditionally "pack-objects [options] base extra" failed;
	 * we would however want to take refs parameter that would
	 * have been given to upstream rev-list ourselves, which means
	 * we somehow want to say what the base name is.  So the
	 * syntax would be:
	 *
	 * pack-objects [options] base <refs...>
	 *
	 * in other words, we would treat the first non-option as the
	 * base_name and send everything else to the internal revision
	 * walker.
	 */
 
	if (!pack_to_stdout)
		base_name = argv[i++];
 
	if (pack_to_stdout != !base_name)
		usage(pack_usage);
 
	if (!pack_to_stdout && thin)
		die("--thin cannot be used to build an indexable pack.");
 
	prepare_packed_git();
 
	if (progress) {
		fprintf(stderr, "Generating pack...\n");
		setup_progress_signal();
	}
 
	if (!use_internal_rev_list)
		read_object_list_from_stdin();
	else {
		rp_av[rp_ac] = NULL;
		get_object_list(rp_ac, rp_av);
	}
 
	if (progress)
		fprintf(stderr, "Done counting %u objects.\n", nr_objects);
	if (non_empty && !nr_result)
		return 0;
	if (progress && (nr_objects != nr_result))
		fprintf(stderr, "Result has %u objects.\n", nr_result);
	if (nr_result)
		prepare_pack(window, depth);
	if (progress == 1 && pack_to_stdout) {
		/* the other end usually displays progress itself */
		struct itimerval v = {{0,},};
		setitimer(ITIMER_REAL, &v, NULL);
		signal(SIGALRM, SIG_IGN );
		progress_update = 0;
	}
	last_obj_offset = write_pack_file();
	if (!pack_to_stdout) {
		unsigned char object_list_sha1[20];
		mode_t mode = umask(0);
 
		umask(mode);
		mode = 0444 & ~mode;
 
		write_index_file(last_obj_offset, object_list_sha1);
		snprintf(tmpname, sizeof(tmpname), "%s-%s.pack",
			 base_name, sha1_to_hex(object_list_sha1));
		if (adjust_perm(pack_tmp_name, mode))
			die("unable to make temporary pack file readable: %s",
			    strerror(errno));
		if (rename(pack_tmp_name, tmpname))
			die("unable to rename temporary pack file: %s",
			    strerror(errno));
		snprintf(tmpname, sizeof(tmpname), "%s-%s.idx",
			 base_name, sha1_to_hex(object_list_sha1));
		if (adjust_perm(idx_tmp_name, mode))
			die("unable to make temporary index file readable: %s",
			    strerror(errno));
		if (rename(idx_tmp_name, tmpname))
			die("unable to rename temporary index file: %s",
			    strerror(errno));
		puts(sha1_to_hex(object_list_sha1));
	}
	if (progress)
		fprintf(stderr, "Total %u (delta %u), reused %u (delta %u)\n",
			written, written_delta, reused, reused_delta);
	return 0;
}