summaryrefslogtreecommitdiff
path: root/builtin/pack-objects.c
blob: f294dcffa90aa3d8c916e448a4de905fa6363d26 (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
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
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
#include "builtin.h"
#include "cache.h"
#include "attr.h"
#include "object.h"
#include "blob.h"
#include "commit.h"
#include "tag.h"
#include "tree.h"
#include "delta.h"
#include "pack.h"
#include "pack-revindex.h"
#include "csum-file.h"
#include "tree-walk.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "pack-objects.h"
#include "progress.h"
#include "refs.h"
#include "streaming.h"
#include "thread-utils.h"
#include "pack-bitmap.h"
#include "reachable.h"
#include "sha1-array.h"
#include "argv-array.h"
#include "mru.h"

static const char *pack_usage[] = {
	N_("git pack-objects --stdout [<options>...] [< <ref-list> | < <object-list>]"),
	N_("git pack-objects [<options>...] <base-name> [< <ref-list> | < <object-list>]"),
	NULL
};

/*
 * Objects we are going to pack are collected in the `to_pack` structure.
 * It contains an array (dynamically expanded) of the object data, and a map
 * that can resolve SHA1s to their position in the array.
 */
static struct packing_data to_pack;

static struct pack_idx_entry **written_list;
static uint32_t nr_result, nr_written;

static int non_empty;
static int reuse_delta = 1, reuse_object = 1;
static int keep_unreachable, unpack_unreachable, include_tag;
static unsigned long unpack_unreachable_expiration;
static int pack_loose_unreachable;
static int local;
static int have_non_local_packs;
static int incremental;
static int ignore_packed_keep;
static int allow_ofs_delta;
static struct pack_idx_option pack_idx_opts;
static const char *base_name;
static int progress = 1;
static int window = 10;
static unsigned long pack_size_limit;
static int depth = 50;
static int delta_search_threads;
static int pack_to_stdout;
static int num_preferred_base;
static struct progress *progress_state;

static struct packed_git *reuse_packfile;
static uint32_t reuse_packfile_objects;
static off_t reuse_packfile_offset;

static int use_bitmap_index_default = 1;
static int use_bitmap_index = -1;
static int write_bitmap_index;
static uint16_t write_bitmap_options;

static unsigned long delta_cache_size = 0;
static unsigned long max_delta_cache_size = 256 * 1024 * 1024;
static unsigned long cache_max_small_delta_size = 1000;

static unsigned long window_memory_limit = 0;

/*
 * stats
 */
static uint32_t written, written_delta;
static uint32_t reused, reused_delta;

/*
 * Indexed commits
 */
static struct commit **indexed_commits;
static unsigned int indexed_commits_nr;
static unsigned int indexed_commits_alloc;

static void index_commit_for_bitmap(struct commit *commit)
{
	if (indexed_commits_nr >= indexed_commits_alloc) {
		indexed_commits_alloc = (indexed_commits_alloc + 32) * 2;
		REALLOC_ARRAY(indexed_commits, indexed_commits_alloc);
	}

	indexed_commits[indexed_commits_nr++] = commit;
}

static void *get_delta(struct object_entry *entry)
{
	unsigned long size, base_size, delta_size;
	void *buf, *base_buf, *delta_buf;
	enum object_type type;

	buf = read_sha1_file(entry->idx.sha1, &type, &size);
	if (!buf)
		die("unable to read %s", sha1_to_hex(entry->idx.sha1));
	base_buf = read_sha1_file(entry->delta->idx.sha1, &type, &base_size);
	if (!base_buf)
		die("unable to read %s", sha1_to_hex(entry->delta->idx.sha1));
	delta_buf = diff_delta(base_buf, base_size,
			       buf, size, &delta_size, 0);
	if (!delta_buf || delta_size != entry->delta_size)
		die("delta size changed");
	free(buf);
	free(base_buf);
	return delta_buf;
}

static unsigned long do_compress(void **pptr, unsigned long size)
{
	git_zstream stream;
	void *in, *out;
	unsigned long maxsize;

	git_deflate_init(&stream, pack_compression_level);
	maxsize = git_deflate_bound(&stream, size);

	in = *pptr;
	out = xmalloc(maxsize);
	*pptr = out;

	stream.next_in = in;
	stream.avail_in = size;
	stream.next_out = out;
	stream.avail_out = maxsize;
	while (git_deflate(&stream, Z_FINISH) == Z_OK)
		; /* nothing */
	git_deflate_end(&stream);

	free(in);
	return stream.total_out;
}

static unsigned long write_large_blob_data(struct git_istream *st, struct sha1file *f,
					   const unsigned char *sha1)
{
	git_zstream stream;
	unsigned char ibuf[1024 * 16];
	unsigned char obuf[1024 * 16];
	unsigned long olen = 0;

	git_deflate_init(&stream, pack_compression_level);

	for (;;) {
		ssize_t readlen;
		int zret = Z_OK;
		readlen = read_istream(st, ibuf, sizeof(ibuf));
		if (readlen == -1)
			die(_("unable to read %s"), sha1_to_hex(sha1));

		stream.next_in = ibuf;
		stream.avail_in = readlen;
		while ((stream.avail_in || readlen == 0) &&
		       (zret == Z_OK || zret == Z_BUF_ERROR)) {
			stream.next_out = obuf;
			stream.avail_out = sizeof(obuf);
			zret = git_deflate(&stream, readlen ? 0 : Z_FINISH);
			sha1write(f, obuf, stream.next_out - obuf);
			olen += stream.next_out - obuf;
		}
		if (stream.avail_in)
			die(_("deflate error (%d)"), zret);
		if (readlen == 0) {
			if (zret != Z_STREAM_END)
				die(_("deflate error (%d)"), zret);
			break;
		}
	}
	git_deflate_end(&stream);
	return olen;
}

/*
 * 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)
{
	git_zstream stream;
	unsigned char fakebuf[4096], *in;
	int st;

	memset(&stream, 0, sizeof(stream));
	git_inflate_init(&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 = git_inflate(&stream, Z_FINISH);
		offset += stream.next_in - in;
	} while (st == Z_OK || st == Z_BUF_ERROR);
	git_inflate_end(&stream);
	return (st == Z_STREAM_END &&
		stream.total_out == expect &&
		stream.total_in == len) ? 0 : -1;
}

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 long avail;

	while (len) {
		in = use_pack(p, w_curs, offset, &avail);
		if (avail > len)
			avail = (unsigned long)len;
		sha1write(f, in, avail);
		offset += avail;
		len -= avail;
	}
}

/* Return 0 if we will bust the pack-size limit */
static unsigned long write_no_reuse_object(struct sha1file *f, struct object_entry *entry,
					   unsigned long limit, int usable_delta)
{
	unsigned long size, datalen;
	unsigned char header[10], dheader[10];
	unsigned hdrlen;
	enum object_type type;
	void *buf;
	struct git_istream *st = NULL;

	if (!usable_delta) {
		if (entry->type == OBJ_BLOB &&
		    entry->size > big_file_threshold &&
		    (st = open_istream(entry->idx.sha1, &type, &size, NULL)) != NULL)
			buf = NULL;
		else {
			buf = read_sha1_file(entry->idx.sha1, &type, &size);
			if (!buf)
				die(_("unable to read %s"), sha1_to_hex(entry->idx.sha1));
		}
		/*
		 * make sure no cached delta data remains from a
		 * previous attempt before a pack split occurred.
		 */
		free(entry->delta_data);
		entry->delta_data = NULL;
		entry->z_delta_size = 0;
	} else if (entry->delta_data) {
		size = entry->delta_size;
		buf = entry->delta_data;
		entry->delta_data = NULL;
		type = (allow_ofs_delta && entry->delta->idx.offset) ?
			OBJ_OFS_DELTA : OBJ_REF_DELTA;
	} else {
		buf = get_delta(entry);
		size = entry->delta_size;
		type = (allow_ofs_delta && entry->delta->idx.offset) ?
			OBJ_OFS_DELTA : OBJ_REF_DELTA;
	}

	if (st)	/* large blob case, just assume we don't compress well */
		datalen = size;
	else if (entry->z_delta_size)
		datalen = entry->z_delta_size;
	else
		datalen = do_compress(&buf, size);

	/*
	 * The object header is a byte of 'type' followed by zero or
	 * more bytes of length.
	 */
	hdrlen = encode_in_pack_object_header(type, size, header);

	if (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->idx.offset - entry->delta->idx.offset;
		unsigned pos = sizeof(dheader) - 1;
		dheader[pos] = ofs & 127;
		while (ofs >>= 7)
			dheader[--pos] = 128 | (--ofs & 127);
		if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
			if (st)
				close_istream(st);
			free(buf);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, dheader + pos, sizeof(dheader) - pos);
		hdrlen += sizeof(dheader) - pos;
	} else if (type == OBJ_REF_DELTA) {
		/*
		 * Deltas with a base reference contain
		 * an additional 20 bytes for the base sha1.
		 */
		if (limit && hdrlen + 20 + datalen + 20 >= limit) {
			if (st)
				close_istream(st);
			free(buf);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, entry->delta->idx.sha1, 20);
		hdrlen += 20;
	} else {
		if (limit && hdrlen + datalen + 20 >= limit) {
			if (st)
				close_istream(st);
			free(buf);
			return 0;
		}
		sha1write(f, header, hdrlen);
	}
	if (st) {
		datalen = write_large_blob_data(st, f, entry->idx.sha1);
		close_istream(st);
	} else {
		sha1write(f, buf, datalen);
		free(buf);
	}

	return hdrlen + datalen;
}

/* Return 0 if we will bust the pack-size limit */
static off_t write_reuse_object(struct sha1file *f, struct object_entry *entry,
				unsigned long limit, int usable_delta)
{
	struct packed_git *p = entry->in_pack;
	struct pack_window *w_curs = NULL;
	struct revindex_entry *revidx;
	off_t offset;
	enum object_type type = entry->type;
	off_t datalen;
	unsigned char header[10], dheader[10];
	unsigned hdrlen;

	if (entry->delta)
		type = (allow_ofs_delta && entry->delta->idx.offset) ?
			OBJ_OFS_DELTA : OBJ_REF_DELTA;
	hdrlen = encode_in_pack_object_header(type, entry->size, header);

	offset = entry->in_pack_offset;
	revidx = find_pack_revindex(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)) {
		error("bad packed object CRC for %s", sha1_to_hex(entry->idx.sha1));
		unuse_pack(&w_curs);
		return write_no_reuse_object(f, entry, limit, usable_delta);
	}

	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)) {
		error("corrupt packed object for %s", sha1_to_hex(entry->idx.sha1));
		unuse_pack(&w_curs);
		return write_no_reuse_object(f, entry, limit, usable_delta);
	}

	if (type == OBJ_OFS_DELTA) {
		off_t ofs = entry->idx.offset - entry->delta->idx.offset;
		unsigned pos = sizeof(dheader) - 1;
		dheader[pos] = ofs & 127;
		while (ofs >>= 7)
			dheader[--pos] = 128 | (--ofs & 127);
		if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, dheader + pos, sizeof(dheader) - pos);
		hdrlen += sizeof(dheader) - pos;
		reused_delta++;
	} else if (type == OBJ_REF_DELTA) {
		if (limit && hdrlen + 20 + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
		sha1write(f, entry->delta->idx.sha1, 20);
		hdrlen += 20;
		reused_delta++;
	} else {
		if (limit && hdrlen + datalen + 20 >= limit) {
			unuse_pack(&w_curs);
			return 0;
		}
		sha1write(f, header, hdrlen);
	}
	copy_pack_data(f, p, &w_curs, offset, datalen);
	unuse_pack(&w_curs);
	reused++;
	return hdrlen + datalen;
}

/* Return 0 if we will bust the pack-size limit */
static off_t write_object(struct sha1file *f,
			  struct object_entry *entry,
			  off_t write_offset)
{
	unsigned long limit;
	off_t len;
	int usable_delta, to_reuse;

	if (!pack_to_stdout)
		crc32_begin(f);

	/* apply size limit if limited packsize and not first object */
	if (!pack_size_limit || !nr_written)
		limit = 0;
	else if (pack_size_limit <= write_offset)
		/*
		 * the earlier object did not fit the limit; avoid
		 * mistaking this with unlimited (i.e. limit = 0).
		 */
		limit = 1;
	else
		limit = pack_size_limit - write_offset;

	if (!entry->delta)
		usable_delta = 0;	/* no delta */
	else if (!pack_size_limit)
	       usable_delta = 1;	/* unlimited packfile */
	else if (entry->delta->idx.offset == (off_t)-1)
		usable_delta = 0;	/* base was written to another pack */
	else if (entry->delta->idx.offset)
		usable_delta = 1;	/* base already exists in this pack */
	else
		usable_delta = 0;	/* base could end up in another pack */

	if (!reuse_object)
		to_reuse = 0;	/* explicit */
	else if (!entry->in_pack)
		to_reuse = 0;	/* can't reuse what we don't have */
	else if (entry->type == OBJ_REF_DELTA || entry->type == OBJ_OFS_DELTA)
				/* check_object() decided it for us ... */
		to_reuse = usable_delta;
				/* ... but pack split may override that */
	else if (entry->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 (!to_reuse)
		len = write_no_reuse_object(f, entry, limit, usable_delta);
	else
		len = write_reuse_object(f, entry, limit, usable_delta);
	if (!len)
		return 0;

	if (usable_delta)
		written_delta++;
	written++;
	if (!pack_to_stdout)
		entry->idx.crc32 = crc32_end(f);
	return len;
}

enum write_one_status {
	WRITE_ONE_SKIP = -1, /* already written */
	WRITE_ONE_BREAK = 0, /* writing this will bust the limit; not written */
	WRITE_ONE_WRITTEN = 1, /* normal */
	WRITE_ONE_RECURSIVE = 2 /* already scheduled to be written */
};

static enum write_one_status write_one(struct sha1file *f,
				       struct object_entry *e,
				       off_t *offset)
{
	off_t size;
	int recursing;

	/*
	 * we set offset to 1 (which is an impossible value) to mark
	 * the fact that this object is involved in "write its base
	 * first before writing a deltified object" recursion.
	 */
	recursing = (e->idx.offset == 1);
	if (recursing) {
		warning("recursive delta detected for object %s",
			sha1_to_hex(e->idx.sha1));
		return WRITE_ONE_RECURSIVE;
	} else if (e->idx.offset || e->preferred_base) {
		/* offset is non zero if object is written already. */
		return WRITE_ONE_SKIP;
	}

	/* if we are deltified, write out base object first. */
	if (e->delta) {
		e->idx.offset = 1; /* now recurse */
		switch (write_one(f, e->delta, offset)) {
		case WRITE_ONE_RECURSIVE:
			/* we cannot depend on this one */
			e->delta = NULL;
			break;
		default:
			break;
		case WRITE_ONE_BREAK:
			e->idx.offset = recursing;
			return WRITE_ONE_BREAK;
		}
	}

	e->idx.offset = *offset;
	size = write_object(f, e, *offset);
	if (!size) {
		e->idx.offset = recursing;
		return WRITE_ONE_BREAK;
	}
	written_list[nr_written++] = &e->idx;

	/* make sure off_t is sufficiently large not to wrap */
	if (signed_add_overflows(*offset, size))
		die("pack too large for current definition of off_t");
	*offset += size;
	return WRITE_ONE_WRITTEN;
}

static int mark_tagged(const char *path, const struct object_id *oid, int flag,
		       void *cb_data)
{
	unsigned char peeled[20];
	struct object_entry *entry = packlist_find(&to_pack, oid->hash, NULL);

	if (entry)
		entry->tagged = 1;
	if (!peel_ref(path, peeled)) {
		entry = packlist_find(&to_pack, peeled, NULL);
		if (entry)
			entry->tagged = 1;
	}
	return 0;
}

static inline void add_to_write_order(struct object_entry **wo,
			       unsigned int *endp,
			       struct object_entry *e)
{
	if (e->filled)
		return;
	wo[(*endp)++] = e;
	e->filled = 1;
}

static void add_descendants_to_write_order(struct object_entry **wo,
					   unsigned int *endp,
					   struct object_entry *e)
{
	int add_to_order = 1;
	while (e) {
		if (add_to_order) {
			struct object_entry *s;
			/* add this node... */
			add_to_write_order(wo, endp, e);
			/* all its siblings... */
			for (s = e->delta_sibling; s; s = s->delta_sibling) {
				add_to_write_order(wo, endp, s);
			}
		}
		/* drop down a level to add left subtree nodes if possible */
		if (e->delta_child) {
			add_to_order = 1;
			e = e->delta_child;
		} else {
			add_to_order = 0;
			/* our sibling might have some children, it is next */
			if (e->delta_sibling) {
				e = e->delta_sibling;
				continue;
			}
			/* go back to our parent node */
			e = e->delta;
			while (e && !e->delta_sibling) {
				/* we're on the right side of a subtree, keep
				 * going up until we can go right again */
				e = e->delta;
			}
			if (!e) {
				/* done- we hit our original root node */
				return;
			}
			/* pass it off to sibling at this level */
			e = e->delta_sibling;
		}
	};
}

static void add_family_to_write_order(struct object_entry **wo,
				      unsigned int *endp,
				      struct object_entry *e)
{
	struct object_entry *root;

	for (root = e; root->delta; root = root->delta)
		; /* nothing */
	add_descendants_to_write_order(wo, endp, root);
}

static struct object_entry **compute_write_order(void)
{
	unsigned int i, wo_end, last_untagged;

	struct object_entry **wo;
	struct object_entry *objects = to_pack.objects;

	for (i = 0; i < to_pack.nr_objects; i++) {
		objects[i].tagged = 0;
		objects[i].filled = 0;
		objects[i].delta_child = NULL;
		objects[i].delta_sibling = NULL;
	}

	/*
	 * Fully connect delta_child/delta_sibling network.
	 * Make sure delta_sibling is sorted in the original
	 * recency order.
	 */
	for (i = to_pack.nr_objects; i > 0;) {
		struct object_entry *e = &objects[--i];
		if (!e->delta)
			continue;
		/* Mark me as the first child */
		e->delta_sibling = e->delta->delta_child;
		e->delta->delta_child = e;
	}

	/*
	 * Mark objects that are at the tip of tags.
	 */
	for_each_tag_ref(mark_tagged, NULL);

	/*
	 * Give the objects in the original recency order until
	 * we see a tagged tip.
	 */
	ALLOC_ARRAY(wo, to_pack.nr_objects);
	for (i = wo_end = 0; i < to_pack.nr_objects; i++) {
		if (objects[i].tagged)
			break;
		add_to_write_order(wo, &wo_end, &objects[i]);
	}
	last_untagged = i;

	/*
	 * Then fill all the tagged tips.
	 */
	for (; i < to_pack.nr_objects; i++) {
		if (objects[i].tagged)
			add_to_write_order(wo, &wo_end, &objects[i]);
	}

	/*
	 * And then all remaining commits and tags.
	 */
	for (i = last_untagged; i < to_pack.nr_objects; i++) {
		if (objects[i].type != OBJ_COMMIT &&
		    objects[i].type != OBJ_TAG)
			continue;
		add_to_write_order(wo, &wo_end, &objects[i]);
	}

	/*
	 * And then all the trees.
	 */
	for (i = last_untagged; i < to_pack.nr_objects; i++) {
		if (objects[i].type != OBJ_TREE)
			continue;
		add_to_write_order(wo, &wo_end, &objects[i]);
	}

	/*
	 * Finally all the rest in really tight order
	 */
	for (i = last_untagged; i < to_pack.nr_objects; i++) {
		if (!objects[i].filled)
			add_family_to_write_order(wo, &wo_end, &objects[i]);
	}

	if (wo_end != to_pack.nr_objects)
		die("ordered %u objects, expected %"PRIu32, wo_end, to_pack.nr_objects);

	return wo;
}

static off_t write_reused_pack(struct sha1file *f)
{
	unsigned char buffer[8192];
	off_t to_write, total;
	int fd;

	if (!is_pack_valid(reuse_packfile))
		die("packfile is invalid: %s", reuse_packfile->pack_name);

	fd = git_open(reuse_packfile->pack_name);
	if (fd < 0)
		die_errno("unable to open packfile for reuse: %s",
			  reuse_packfile->pack_name);

	if (lseek(fd, sizeof(struct pack_header), SEEK_SET) == -1)
		die_errno("unable to seek in reused packfile");

	if (reuse_packfile_offset < 0)
		reuse_packfile_offset = reuse_packfile->pack_size - 20;

	total = to_write = reuse_packfile_offset - sizeof(struct pack_header);

	while (to_write) {
		int read_pack = xread(fd, buffer, sizeof(buffer));

		if (read_pack <= 0)
			die_errno("unable to read from reused packfile");

		if (read_pack > to_write)
			read_pack = to_write;

		sha1write(f, buffer, read_pack);
		to_write -= read_pack;

		/*
		 * We don't know the actual number of objects written,
		 * only how many bytes written, how many bytes total, and
		 * how many objects total. So we can fake it by pretending all
		 * objects we are writing are the same size. This gives us a
		 * smooth progress meter, and at the end it matches the true
		 * answer.
		 */
		written = reuse_packfile_objects *
				(((double)(total - to_write)) / total);
		display_progress(progress_state, written);
	}

	close(fd);
	written = reuse_packfile_objects;
	display_progress(progress_state, written);
	return reuse_packfile_offset - sizeof(struct pack_header);
}

static const char no_split_warning[] = N_(
"disabling bitmap writing, packs are split due to pack.packSizeLimit"
);

static void write_pack_file(void)
{
	uint32_t i = 0, j;
	struct sha1file *f;
	off_t offset;
	uint32_t nr_remaining = nr_result;
	time_t last_mtime = 0;
	struct object_entry **write_order;

	if (progress > pack_to_stdout)
		progress_state = start_progress(_("Writing objects"), nr_result);
	ALLOC_ARRAY(written_list, to_pack.nr_objects);
	write_order = compute_write_order();

	do {
		unsigned char sha1[20];
		char *pack_tmp_name = NULL;

		if (pack_to_stdout)
			f = sha1fd_throughput(1, "<stdout>", progress_state);
		else
			f = create_tmp_packfile(&pack_tmp_name);

		offset = write_pack_header(f, nr_remaining);

		if (reuse_packfile) {
			off_t packfile_size;
			assert(pack_to_stdout);

			packfile_size = write_reused_pack(f);
			offset += packfile_size;
		}

		nr_written = 0;
		for (; i < to_pack.nr_objects; i++) {
			struct object_entry *e = write_order[i];
			if (write_one(f, e, &offset) == WRITE_ONE_BREAK)
				break;
			display_progress(progress_state, written);
		}

		/*
		 * Did we write the wrong # entries in the header?
		 * If so, rewrite it like in fast-import
		 */
		if (pack_to_stdout) {
			sha1close(f, sha1, CSUM_CLOSE);
		} else if (nr_written == nr_remaining) {
			sha1close(f, sha1, CSUM_FSYNC);
		} else {
			int fd = sha1close(f, sha1, 0);
			fixup_pack_header_footer(fd, sha1, pack_tmp_name,
						 nr_written, sha1, offset);
			close(fd);
			if (write_bitmap_index) {
				warning(_(no_split_warning));
				write_bitmap_index = 0;
			}
		}

		if (!pack_to_stdout) {
			struct stat st;
			struct strbuf tmpname = STRBUF_INIT;

			/*
			 * Packs are runtime accessed in their mtime
			 * order since newer packs are more likely to contain
			 * younger objects.  So if we are creating multiple
			 * packs then we should modify the mtime of later ones
			 * to preserve this property.
			 */
			if (stat(pack_tmp_name, &st) < 0) {
				warning_errno("failed to stat %s", pack_tmp_name);
			} else if (!last_mtime) {
				last_mtime = st.st_mtime;
			} else {
				struct utimbuf utb;
				utb.actime = st.st_atime;
				utb.modtime = --last_mtime;
				if (utime(pack_tmp_name, &utb) < 0)
					warning_errno("failed utime() on %s", pack_tmp_name);
			}

			strbuf_addf(&tmpname, "%s-", base_name);

			if (write_bitmap_index) {
				bitmap_writer_set_checksum(sha1);
				bitmap_writer_build_type_index(written_list, nr_written);
			}

			finish_tmp_packfile(&tmpname, pack_tmp_name,
					    written_list, nr_written,
					    &pack_idx_opts, sha1);

			if (write_bitmap_index) {
				strbuf_addf(&tmpname, "%s.bitmap", sha1_to_hex(sha1));

				stop_progress(&progress_state);

				bitmap_writer_show_progress(progress);
				bitmap_writer_reuse_bitmaps(&to_pack);
				bitmap_writer_select_commits(indexed_commits, indexed_commits_nr, -1);
				bitmap_writer_build(&to_pack);
				bitmap_writer_finish(written_list, nr_written,
						     tmpname.buf, write_bitmap_options);
				write_bitmap_index = 0;
			}

			strbuf_release(&tmpname);
			free(pack_tmp_name);
			puts(sha1_to_hex(sha1));
		}

		/* mark written objects as written to previous pack */
		for (j = 0; j < nr_written; j++) {
			written_list[j]->offset = (off_t)-1;
		}
		nr_remaining -= nr_written;
	} while (nr_remaining && i < to_pack.nr_objects);

	free(written_list);
	free(write_order);
	stop_progress(&progress_state);
	if (written != nr_result)
		die("wrote %"PRIu32" objects while expecting %"PRIu32,
			written, nr_result);
}

static int no_try_delta(const char *path)
{
	static struct attr_check *check;

	if (!check)
		check = attr_check_initl("delta", NULL);
	if (git_check_attr(path, check))
		return 0;
	if (ATTR_FALSE(check->items[0].value))
		return 1;
	return 0;
}

/*
 * When adding an object, check whether we have already added it
 * to our packing list. If so, we can skip. However, if we are
 * being asked to excludei t, but the previous mention was to include
 * it, make sure to adjust its flags and tweak our numbers accordingly.
 *
 * As an optimization, we pass out the index position where we would have
 * found the item, since that saves us from having to look it up again a
 * few lines later when we want to add the new entry.
 */
static int have_duplicate_entry(const unsigned char *sha1,
				int exclude,
				uint32_t *index_pos)
{
	struct object_entry *entry;

	entry = packlist_find(&to_pack, sha1, index_pos);
	if (!entry)
		return 0;

	if (exclude) {
		if (!entry->preferred_base)
			nr_result--;
		entry->preferred_base = 1;
	}

	return 1;
}

static int want_found_object(int exclude, struct packed_git *p)
{
	if (exclude)
		return 1;
	if (incremental)
		return 0;

	/*
	 * When asked to do --local (do not include an object that appears in a
	 * pack we borrow from elsewhere) or --honor-pack-keep (do not include
	 * an object that appears in a pack marked with .keep), finding a pack
	 * that matches the criteria is sufficient for us to decide to omit it.
	 * However, even if this pack does not satisfy the criteria, we need to
	 * make sure no copy of this object appears in _any_ pack that makes us
	 * to omit the object, so we need to check all the packs.
	 *
	 * We can however first check whether these options can possible matter;
	 * if they do not matter we know we want the object in generated pack.
	 * Otherwise, we signal "-1" at the end to tell the caller that we do
	 * not know either way, and it needs to check more packs.
	 */
	if (!ignore_packed_keep &&
	    (!local || !have_non_local_packs))
		return 1;

	if (local && !p->pack_local)
		return 0;
	if (ignore_packed_keep && p->pack_local && p->pack_keep)
		return 0;

	/* we don't know yet; keep looking for more packs */
	return -1;
}

/*
 * Check whether we want the object in the pack (e.g., we do not want
 * objects found in non-local stores if the "--local" option was used).
 *
 * If the caller already knows an existing pack it wants to take the object
 * from, that is passed in *found_pack and *found_offset; otherwise this
 * function finds if there is any pack that has the object and returns the pack
 * and its offset in these variables.
 */
static int want_object_in_pack(const unsigned char *sha1,
			       int exclude,
			       struct packed_git **found_pack,
			       off_t *found_offset)
{
	struct mru_entry *entry;
	int want;

	if (!exclude && local && has_loose_object_nonlocal(sha1))
		return 0;

	/*
	 * If we already know the pack object lives in, start checks from that
	 * pack - in the usual case when neither --local was given nor .keep files
	 * are present we will determine the answer right now.
	 */
	if (*found_pack) {
		want = want_found_object(exclude, *found_pack);
		if (want != -1)
			return want;
	}

	for (entry = packed_git_mru->head; entry; entry = entry->next) {
		struct packed_git *p = entry->item;
		off_t offset;

		if (p == *found_pack)
			offset = *found_offset;
		else
			offset = find_pack_entry_one(sha1, p);

		if (offset) {
			if (!*found_pack) {
				if (!is_pack_valid(p))
					continue;
				*found_offset = offset;
				*found_pack = p;
			}
			want = want_found_object(exclude, p);
			if (!exclude && want > 0)
				mru_mark(packed_git_mru, entry);
			if (want != -1)
				return want;
		}
	}

	return 1;
}

static void create_object_entry(const unsigned char *sha1,
				enum object_type type,
				uint32_t hash,
				int exclude,
				int no_try_delta,
				uint32_t index_pos,
				struct packed_git *found_pack,
				off_t found_offset)
{
	struct object_entry *entry;

	entry = packlist_alloc(&to_pack, sha1, index_pos);
	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;
	}

	entry->no_try_delta = no_try_delta;
}

static const char no_closure_warning[] = N_(
"disabling bitmap writing, as some objects are not being packed"
);

static int add_object_entry(const unsigned char *sha1, enum object_type type,
			    const char *name, int exclude)
{
	struct packed_git *found_pack = NULL;
	off_t found_offset = 0;
	uint32_t index_pos;

	if (have_duplicate_entry(sha1, exclude, &index_pos))
		return 0;

	if (!want_object_in_pack(sha1, exclude, &found_pack, &found_offset)) {
		/* The pack is missing an object, so it will not have closure */
		if (write_bitmap_index) {
			warning(_(no_closure_warning));
			write_bitmap_index = 0;
		}
		return 0;
	}

	create_object_entry(sha1, type, pack_name_hash(name),
			    exclude, name && no_try_delta(name),
			    index_pos, found_pack, found_offset);

	display_progress(progress_state, nr_result);
	return 1;
}

static int add_object_entry_from_bitmap(const unsigned char *sha1,
					enum object_type type,
					int flags, uint32_t name_hash,
					struct packed_git *pack, off_t offset)
{
	uint32_t index_pos;

	if (have_duplicate_entry(sha1, 0, &index_pos))
		return 0;

	if (!want_object_in_pack(sha1, 0, &pack, &offset))
		return 0;

	create_object_entry(sha1, type, name_hash, 0, 0, index_pos, pack, offset);

	display_progress(progress_state, nr_result);
	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 or 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)) {
		if (S_ISGITLINK(entry.mode))
			continue;
		cmp = tree_entry_len(&entry) != cmplen ? 1 :
		      memcmp(name, entry.path, cmplen);
		if (cmp > 0)
			continue;
		if (cmp < 0)
			return;
		if (name[cmplen] != '/') {
			add_object_entry(entry.oid->hash,
					 object_type(entry.mode),
					 fullname, 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.oid->hash);
			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;
	ALLOC_GROW(done_pbase_paths,
		   done_pbase_paths_num + 1,
		   done_pbase_paths_alloc);
	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)
{
	struct pbase_tree *it;
	int cmplen;
	unsigned hash = pack_name_hash(name);

	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, NULL, 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 cleanup_preferred_base(void)
{
	struct pbase_tree *it;
	unsigned i;

	it = pbase_tree;
	pbase_tree = NULL;
	while (it) {
		struct pbase_tree *this = it;
		it = this->next;
		free(this->pcache.tree_data);
		free(this);
	}

	for (i = 0; i < ARRAY_SIZE(pbase_tree_cache); i++) {
		if (!pbase_tree_cache[i])
			continue;
		free(pbase_tree_cache[i]->tree_data);
		free(pbase_tree_cache[i]);
		pbase_tree_cache[i] = NULL;
	}

	free(done_pbase_paths);
	done_pbase_paths = NULL;
	done_pbase_paths_num = done_pbase_paths_alloc = 0;
}

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 long 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
		 * since non-delta representations could still be reused.
		 */
		used = unpack_object_header_buffer(buf, avail,
						   &entry->in_pack_type,
						   &entry->size);
		if (used == 0)
			goto give_up;

		/*
		 * 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;
			if (entry->type < OBJ_COMMIT || entry->type > OBJ_BLOB)
				goto give_up;
			unuse_pack(&w_curs);
			return;
		case OBJ_REF_DELTA:
			if (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)) {
					error("delta base offset overflow in pack for %s",
					      sha1_to_hex(entry->idx.sha1));
					goto give_up;
				}
				c = buf[used_0++];
				ofs = (ofs << 7) + (c & 127);
			}
			ofs = entry->in_pack_offset - ofs;
			if (ofs <= 0 || ofs >= entry->in_pack_offset) {
				error("delta base offset out of bound for %s",
				      sha1_to_hex(entry->idx.sha1));
				goto give_up;
			}
			if (reuse_delta && !entry->preferred_base) {
				struct revindex_entry *revidx;
				revidx = find_pack_revindex(p, ofs);
				if (!revidx)
					goto give_up;
				base_ref = nth_packed_object_sha1(p, revidx->nr);
			}
			entry->in_pack_header_size = used + used_0;
			break;
		}

		if (base_ref && (base_entry = packlist_find(&to_pack, base_ref, NULL))) {
			/*
			 * 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_size = entry->size;
			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);
			if (entry->size == 0)
				goto give_up;
			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...
		 */
		give_up:
		unuse_pack(&w_curs);
	}

	entry->type = sha1_object_info(entry->idx.sha1, &entry->size);
	/*
	 * The error condition is checked in prepare_pack().  This is
	 * to permit a missing preferred base object to be ignored
	 * as a preferred base.  Doing so can result in a larger
	 * pack file, but the transfer will still take place.
	 */
}

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->idx.sha1, b->idx.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);
}

/*
 * Drop an on-disk delta we were planning to reuse. Naively, this would
 * just involve blanking out the "delta" field, but we have to deal
 * with some extra book-keeping:
 *
 *   1. Removing ourselves from the delta_sibling linked list.
 *
 *   2. Updating our size/type to the non-delta representation. These were
 *      either not recorded initially (size) or overwritten with the delta type
 *      (type) when check_object() decided to reuse the delta.
 *
 *   3. Resetting our delta depth, as we are now a base object.
 */
static void drop_reused_delta(struct object_entry *entry)
{
	struct object_entry **p = &entry->delta->delta_child;
	struct object_info oi = OBJECT_INFO_INIT;

	while (*p) {
		if (*p == entry)
			*p = (*p)->delta_sibling;
		else
			p = &(*p)->delta_sibling;
	}
	entry->delta = NULL;
	entry->depth = 0;

	oi.sizep = &entry->size;
	oi.typep = &entry->type;
	if (packed_object_info(entry->in_pack, entry->in_pack_offset, &oi) < 0) {
		/*
		 * We failed to get the info from this pack for some reason;
		 * fall back to sha1_object_info, which may find another copy.
		 * And if that fails, the error will be recorded in entry->type
		 * and dealt with in prepare_pack().
		 */
		entry->type = sha1_object_info(entry->idx.sha1, &entry->size);
	}
}

/*
 * Follow the chain of deltas from this entry onward, throwing away any links
 * that cause us to hit a cycle (as determined by the DFS state flags in
 * the entries).
 *
 * We also detect too-long reused chains that would violate our --depth
 * limit.
 */
static void break_delta_chains(struct object_entry *entry)
{
	/*
	 * The actual depth of each object we will write is stored as an int,
	 * as it cannot exceed our int "depth" limit. But before we break
	 * changes based no that limit, we may potentially go as deep as the
	 * number of objects, which is elsewhere bounded to a uint32_t.
	 */
	uint32_t total_depth;
	struct object_entry *cur, *next;

	for (cur = entry, total_depth = 0;
	     cur;
	     cur = cur->delta, total_depth++) {
		if (cur->dfs_state == DFS_DONE) {
			/*
			 * We've already seen this object and know it isn't
			 * part of a cycle. We do need to append its depth
			 * to our count.
			 */
			total_depth += cur->depth;
			break;
		}

		/*
		 * We break cycles before looping, so an ACTIVE state (or any
		 * other cruft which made its way into the state variable)
		 * is a bug.
		 */
		if (cur->dfs_state != DFS_NONE)
			die("BUG: confusing delta dfs state in first pass: %d",
			    cur->dfs_state);

		/*
		 * Now we know this is the first time we've seen the object. If
		 * it's not a delta, we're done traversing, but we'll mark it
		 * done to save time on future traversals.
		 */
		if (!cur->delta) {
			cur->dfs_state = DFS_DONE;
			break;
		}

		/*
		 * Mark ourselves as active and see if the next step causes
		 * us to cycle to another active object. It's important to do
		 * this _before_ we loop, because it impacts where we make the
		 * cut, and thus how our total_depth counter works.
		 * E.g., We may see a partial loop like:
		 *
		 *   A -> B -> C -> D -> B
		 *
		 * Cutting B->C breaks the cycle. But now the depth of A is
		 * only 1, and our total_depth counter is at 3. The size of the
		 * error is always one less than the size of the cycle we
		 * broke. Commits C and D were "lost" from A's chain.
		 *
		 * If we instead cut D->B, then the depth of A is correct at 3.
		 * We keep all commits in the chain that we examined.
		 */
		cur->dfs_state = DFS_ACTIVE;
		if (cur->delta->dfs_state == DFS_ACTIVE) {
			drop_reused_delta(cur);
			cur->dfs_state = DFS_DONE;
			break;
		}
	}

	/*
	 * And now that we've gone all the way to the bottom of the chain, we
	 * need to clear the active flags and set the depth fields as
	 * appropriate. Unlike the loop above, which can quit when it drops a
	 * delta, we need to keep going to look for more depth cuts. So we need
	 * an extra "next" pointer to keep going after we reset cur->delta.
	 */
	for (cur = entry; cur; cur = next) {
		next = cur->delta;

		/*
		 * We should have a chain of zero or more ACTIVE states down to
		 * a final DONE. We can quit after the DONE, because either it
		 * has no bases, or we've already handled them in a previous
		 * call.
		 */
		if (cur->dfs_state == DFS_DONE)
			break;
		else if (cur->dfs_state != DFS_ACTIVE)
			die("BUG: confusing delta dfs state in second pass: %d",
			    cur->dfs_state);

		/*
		 * If the total_depth is more than depth, then we need to snip
		 * the chain into two or more smaller chains that don't exceed
		 * the maximum depth. Most of the resulting chains will contain
		 * (depth + 1) entries (i.e., depth deltas plus one base), and
		 * the last chain (i.e., the one containing entry) will contain
		 * whatever entries are left over, namely
		 * (total_depth % (depth + 1)) of them.
		 *
		 * Since we are iterating towards decreasing depth, we need to
		 * decrement total_depth as we go, and we need to write to the
		 * entry what its final depth will be after all of the
		 * snipping. Since we're snipping into chains of length (depth
		 * + 1) entries, the final depth of an entry will be its
		 * original depth modulo (depth + 1). Any time we encounter an
		 * entry whose final depth is supposed to be zero, we snip it
		 * from its delta base, thereby making it so.
		 */
		cur->depth = (total_depth--) % (depth + 1);
		if (!cur->depth)
			drop_reused_delta(cur);

		cur->dfs_state = DFS_DONE;
	}
}

static void get_object_details(void)
{
	uint32_t i;
	struct object_entry **sorted_by_offset;

	sorted_by_offset = xcalloc(to_pack.nr_objects, sizeof(struct object_entry *));
	for (i = 0; i < to_pack.nr_objects; i++)
		sorted_by_offset[i] = to_pack.objects + i;
	QSORT(sorted_by_offset, to_pack.nr_objects, pack_offset_sort);

	for (i = 0; i < to_pack.nr_objects; i++) {
		struct object_entry *entry = sorted_by_offset[i];
		check_object(entry);
		if (big_file_threshold < entry->size)
			entry->no_try_delta = 1;
	}

	/*
	 * This must happen in a second pass, since we rely on the delta
	 * information for the whole list being completed.
	 */
	for (i = 0; i < to_pack.nr_objects; i++)
		break_delta_chains(&to_pack.objects[i]);

	free(sorted_by_offset);
}

/*
 * We search for deltas in a list sorted by type, by filename hash, and then
 * 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.  The deepest deltas are therefore the oldest objects which are
 * less susceptible to be accessed often.
 */
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 first */
}

struct unpacked {
	struct object_entry *entry;
	void *data;
	struct delta_index *index;
	unsigned depth;
};

static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
			   unsigned long delta_size)
{
	if (max_delta_cache_size && delta_cache_size + delta_size > max_delta_cache_size)
		return 0;

	if (delta_size < cache_max_small_delta_size)
		return 1;

	/* cache delta, if objects are large enough compared to delta size */
	if ((src_size >> 20) + (trg_size >> 21) > (delta_size >> 10))
		return 1;

	return 0;
}

#ifndef NO_PTHREADS

static pthread_mutex_t read_mutex;
#define read_lock()		pthread_mutex_lock(&read_mutex)
#define read_unlock()		pthread_mutex_unlock(&read_mutex)

static pthread_mutex_t cache_mutex;
#define cache_lock()		pthread_mutex_lock(&cache_mutex)
#define cache_unlock()		pthread_mutex_unlock(&cache_mutex)

static pthread_mutex_t progress_mutex;
#define progress_lock()		pthread_mutex_lock(&progress_mutex)
#define progress_unlock()	pthread_mutex_unlock(&progress_mutex)

#else

#define read_lock()		(void)0
#define read_unlock()		(void)0
#define cache_lock()		(void)0
#define cache_unlock()		(void)0
#define progress_lock()		(void)0
#define progress_unlock()	(void)0

#endif

static int try_delta(struct unpacked *trg, struct unpacked *src,
		     unsigned max_depth, unsigned long *mem_usage)
{
	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;
	unsigned ref_depth;
	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 bother to try a delta that we discarded on an
	 * earlier try, but only when reusing delta data.  Note that
	 * src_entry that is marked as the preferred_base should always
	 * be considered, as even if we produce a suboptimal delta against
	 * it, we will still save the transfer cost, as we already know
	 * the other side has it and we won't send src_entry at all.
	 */
	if (reuse_delta && trg_entry->in_pack &&
	    trg_entry->in_pack == src_entry->in_pack &&
	    !src_entry->preferred_base &&
	    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->depth >= max_depth)
		return 0;

	/* Now some size filtering heuristics. */
	trg_size = trg_entry->size;
	if (!trg_entry->delta) {
		max_size = trg_size/2 - 20;
		ref_depth = 1;
	} else {
		max_size = trg_entry->delta_size;
		ref_depth = trg->depth;
	}
	max_size = (uint64_t)max_size * (max_depth - src->depth) /
						(max_depth - ref_depth + 1);
	if (max_size == 0)
		return 0;
	src_size = src_entry->size;
	sizediff = src_size < trg_size ? trg_size - src_size : 0;
	if (sizediff >= max_size)
		return 0;
	if (trg_size < src_size / 32)
		return 0;

	/* Load data if not already done */
	if (!trg->data) {
		read_lock();
		trg->data = read_sha1_file(trg_entry->idx.sha1, &type, &sz);
		read_unlock();
		if (!trg->data)
			die("object %s cannot be read",
			    sha1_to_hex(trg_entry->idx.sha1));
		if (sz != trg_size)
			die("object %s inconsistent object length (%lu vs %lu)",
			    sha1_to_hex(trg_entry->idx.sha1), sz, trg_size);
		*mem_usage += sz;
	}
	if (!src->data) {
		read_lock();
		src->data = read_sha1_file(src_entry->idx.sha1, &type, &sz);
		read_unlock();
		if (!src->data) {
			if (src_entry->preferred_base) {
				static int warned = 0;
				if (!warned++)
					warning("object %s cannot be read",
						sha1_to_hex(src_entry->idx.sha1));
				/*
				 * Those objects are not included in the
				 * resulting pack.  Be resilient and ignore
				 * them if they can't be read, in case the
				 * pack could be created nevertheless.
				 */
				return 0;
			}
			die("object %s cannot be read",
			    sha1_to_hex(src_entry->idx.sha1));
		}
		if (sz != src_size)
			die("object %s inconsistent object length (%lu vs %lu)",
			    sha1_to_hex(src_entry->idx.sha1), sz, src_size);
		*mem_usage += sz;
	}
	if (!src->index) {
		src->index = create_delta_index(src->data, src_size);
		if (!src->index) {
			static int warned = 0;
			if (!warned++)
				warning("suboptimal pack - out of memory");
			return 0;
		}
		*mem_usage += sizeof_delta_index(src->index);
	}

	delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
	if (!delta_buf)
		return 0;

	if (trg_entry->delta) {
		/* Prefer only shallower same-sized deltas. */
		if (delta_size == trg_entry->delta_size &&
		    src->depth + 1 >= trg->depth) {
			free(delta_buf);
			return 0;
		}
	}

	/*
	 * Handle memory allocation outside of the cache
	 * accounting lock.  Compiler will optimize the strangeness
	 * away when NO_PTHREADS is defined.
	 */
	free(trg_entry->delta_data);
	cache_lock();
	if (trg_entry->delta_data) {
		delta_cache_size -= trg_entry->delta_size;
		trg_entry->delta_data = NULL;
	}
	if (delta_cacheable(src_size, trg_size, delta_size)) {
		delta_cache_size += delta_size;
		cache_unlock();
		trg_entry->delta_data = xrealloc(delta_buf, delta_size);
	} else {
		cache_unlock();
		free(delta_buf);
	}

	trg_entry->delta = src_entry;
	trg_entry->delta_size = delta_size;
	trg->depth = src->depth + 1;

	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 unsigned long free_unpacked(struct unpacked *n)
{
	unsigned long freed_mem = sizeof_delta_index(n->index);
	free_delta_index(n->index);
	n->index = NULL;
	if (n->data) {
		freed_mem += n->entry->size;
		free(n->data);
		n->data = NULL;
	}
	n->entry = NULL;
	n->depth = 0;
	return freed_mem;
}

static void find_deltas(struct object_entry **list, unsigned *list_size,
			int window, int depth, unsigned *processed)
{
	uint32_t i, idx = 0, count = 0;
	struct unpacked *array;
	unsigned long mem_usage = 0;

	array = xcalloc(window, sizeof(struct unpacked));

	for (;;) {
		struct object_entry *entry;
		struct unpacked *n = array + idx;
		int j, max_depth, best_base = -1;

		progress_lock();
		if (!*list_size) {
			progress_unlock();
			break;
		}
		entry = *list++;
		(*list_size)--;
		if (!entry->preferred_base) {
			(*processed)++;
			display_progress(progress_state, *processed);
		}
		progress_unlock();

		mem_usage -= free_unpacked(n);
		n->entry = entry;

		while (window_memory_limit &&
		       mem_usage > window_memory_limit &&
		       count > 1) {
			uint32_t tail = (idx + window - count) % window;
			mem_usage -= free_unpacked(array + tail);
			count--;
		}

		/* We do not compute delta to *create* objects we are not
		 * going to pack.
		 */
		if (entry->preferred_base)
			goto next;

		/*
		 * 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) {
			int ret;
			uint32_t other_idx = idx + j;
			struct unpacked *m;
			if (other_idx >= window)
				other_idx -= window;
			m = array + other_idx;
			if (!m->entry)
				break;
			ret = try_delta(n, m, max_depth, &mem_usage);
			if (ret < 0)
				break;
			else if (ret > 0)
				best_base = other_idx;
		}

		/*
		 * If we decided to cache the delta data, then it is best
		 * to compress it right away.  First because we have to do
		 * it anyway, and doing it here while we're threaded will
		 * save a lot of time in the non threaded write phase,
		 * as well as allow for caching more deltas within
		 * the same cache size limit.
		 * ...
		 * But only if not writing to stdout, since in that case
		 * the network is most likely throttling writes anyway,
		 * and therefore it is best to go to the write phase ASAP
		 * instead, as we can afford spending more time compressing
		 * between writes at that moment.
		 */
		if (entry->delta_data && !pack_to_stdout) {
			entry->z_delta_size = do_compress(&entry->delta_data,
							  entry->delta_size);
			cache_lock();
			delta_cache_size -= entry->delta_size;
			delta_cache_size += entry->z_delta_size;
			cache_unlock();
		}

		/* 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 && max_depth <= n->depth)
			continue;

		/*
		 * Move the best delta base up in the window, after the
		 * currently deltified object, to keep it longer.  It will
		 * be the first base object to be attempted next.
		 */
		if (entry->delta) {
			struct unpacked swap = array[best_base];
			int dist = (window + idx - best_base) % window;
			int dst = best_base;
			while (dist--) {
				int src = (dst + 1) % window;
				array[dst] = array[src];
				dst = src;
			}
			array[dst] = swap;
		}

		next:
		idx++;
		if (count + 1 < window)
			count++;
		if (idx >= window)
			idx = 0;
	}

	for (i = 0; i < window; ++i) {
		free_delta_index(array[i].index);
		free(array[i].data);
	}
	free(array);
}

#ifndef NO_PTHREADS

static void try_to_free_from_threads(size_t size)
{
	read_lock();
	release_pack_memory(size);
	read_unlock();
}

static try_to_free_t old_try_to_free_routine;

/*
 * The main thread waits on the condition that (at least) one of the workers
 * has stopped working (which is indicated in the .working member of
 * struct thread_params).
 * When a work thread has completed its work, it sets .working to 0 and
 * signals the main thread and waits on the condition that .data_ready
 * becomes 1.
 */

struct thread_params {
	pthread_t thread;
	struct object_entry **list;
	unsigned list_size;
	unsigned remaining;
	int window;
	int depth;
	int working;
	int data_ready;
	pthread_mutex_t mutex;
	pthread_cond_t cond;
	unsigned *processed;
};

static pthread_cond_t progress_cond;

/*
 * Mutex and conditional variable can't be statically-initialized on Windows.
 */
static void init_threaded_search(void)
{
	init_recursive_mutex(&read_mutex);
	pthread_mutex_init(&cache_mutex, NULL);
	pthread_mutex_init(&progress_mutex, NULL);
	pthread_cond_init(&progress_cond, NULL);
	old_try_to_free_routine = set_try_to_free_routine(try_to_free_from_threads);
}

static void cleanup_threaded_search(void)
{
	set_try_to_free_routine(old_try_to_free_routine);
	pthread_cond_destroy(&progress_cond);
	pthread_mutex_destroy(&read_mutex);
	pthread_mutex_destroy(&cache_mutex);
	pthread_mutex_destroy(&progress_mutex);
}

static void *threaded_find_deltas(void *arg)
{
	struct thread_params *me = arg;

	while (me->remaining) {
		find_deltas(me->list, &me->remaining,
			    me->window, me->depth, me->processed);

		progress_lock();
		me->working = 0;
		pthread_cond_signal(&progress_cond);
		progress_unlock();

		/*
		 * We must not set ->data_ready before we wait on the
		 * condition because the main thread may have set it to 1
		 * before we get here. In order to be sure that new
		 * work is available if we see 1 in ->data_ready, it
		 * was initialized to 0 before this thread was spawned
		 * and we reset it to 0 right away.
		 */
		pthread_mutex_lock(&me->mutex);
		while (!me->data_ready)
			pthread_cond_wait(&me->cond, &me->mutex);
		me->data_ready = 0;
		pthread_mutex_unlock(&me->mutex);
	}
	/* leave ->working 1 so that this doesn't get more work assigned */
	return NULL;
}

static void ll_find_deltas(struct object_entry **list, unsigned list_size,
			   int window, int depth, unsigned *processed)
{
	struct thread_params *p;
	int i, ret, active_threads = 0;

	init_threaded_search();

	if (delta_search_threads <= 1) {
		find_deltas(list, &list_size, window, depth, processed);
		cleanup_threaded_search();
		return;
	}
	if (progress > pack_to_stdout)
		fprintf(stderr, "Delta compression using up to %d threads.\n",
				delta_search_threads);
	p = xcalloc(delta_search_threads, sizeof(*p));

	/* Partition the work amongst work threads. */
	for (i = 0; i < delta_search_threads; i++) {
		unsigned sub_size = list_size / (delta_search_threads - i);

		/* don't use too small segments or no deltas will be found */
		if (sub_size < 2*window && i+1 < delta_search_threads)
			sub_size = 0;

		p[i].window = window;
		p[i].depth = depth;
		p[i].processed = processed;
		p[i].working = 1;
		p[i].data_ready = 0;

		/* try to split chunks on "path" boundaries */
		while (sub_size && sub_size < list_size &&
		       list[sub_size]->hash &&
		       list[sub_size]->hash == list[sub_size-1]->hash)
			sub_size++;

		p[i].list = list;
		p[i].list_size = sub_size;
		p[i].remaining = sub_size;

		list += sub_size;
		list_size -= sub_size;
	}

	/* Start work threads. */
	for (i = 0; i < delta_search_threads; i++) {
		if (!p[i].list_size)
			continue;
		pthread_mutex_init(&p[i].mutex, NULL);
		pthread_cond_init(&p[i].cond, NULL);
		ret = pthread_create(&p[i].thread, NULL,
				     threaded_find_deltas, &p[i]);
		if (ret)
			die("unable to create thread: %s", strerror(ret));
		active_threads++;
	}

	/*
	 * Now let's wait for work completion.  Each time a thread is done
	 * with its work, we steal half of the remaining work from the
	 * thread with the largest number of unprocessed objects and give
	 * it to that newly idle thread.  This ensure good load balancing
	 * until the remaining object list segments are simply too short
	 * to be worth splitting anymore.
	 */
	while (active_threads) {
		struct thread_params *target = NULL;
		struct thread_params *victim = NULL;
		unsigned sub_size = 0;

		progress_lock();
		for (;;) {
			for (i = 0; !target && i < delta_search_threads; i++)
				if (!p[i].working)
					target = &p[i];
			if (target)
				break;
			pthread_cond_wait(&progress_cond, &progress_mutex);
		}

		for (i = 0; i < delta_search_threads; i++)
			if (p[i].remaining > 2*window &&
			    (!victim || victim->remaining < p[i].remaining))
				victim = &p[i];
		if (victim) {
			sub_size = victim->remaining / 2;
			list = victim->list + victim->list_size - sub_size;
			while (sub_size && list[0]->hash &&
			       list[0]->hash == list[-1]->hash) {
				list++;
				sub_size--;
			}
			if (!sub_size) {
				/*
				 * It is possible for some "paths" to have
				 * so many objects that no hash boundary
				 * might be found.  Let's just steal the
				 * exact half in that case.
				 */
				sub_size = victim->remaining / 2;
				list -= sub_size;
			}
			target->list = list;
			victim->list_size -= sub_size;
			victim->remaining -= sub_size;
		}
		target->list_size = sub_size;
		target->remaining = sub_size;
		target->working = 1;
		progress_unlock();

		pthread_mutex_lock(&target->mutex);
		target->data_ready = 1;
		pthread_cond_signal(&target->cond);
		pthread_mutex_unlock(&target->mutex);

		if (!sub_size) {
			pthread_join(target->thread, NULL);
			pthread_cond_destroy(&target->cond);
			pthread_mutex_destroy(&target->mutex);
			active_threads--;
		}
	}
	cleanup_threaded_search();
	free(p);
}

#else
#define ll_find_deltas(l, s, w, d, p)	find_deltas(l, &s, w, d, p)
#endif

static void add_tag_chain(const struct object_id *oid)
{
	struct tag *tag;

	/*
	 * We catch duplicates already in add_object_entry(), but we'd
	 * prefer to do this extra check to avoid having to parse the
	 * tag at all if we already know that it's being packed (e.g., if
	 * it was included via bitmaps, we would not have parsed it
	 * previously).
	 */
	if (packlist_find(&to_pack, oid->hash, NULL))
		return;

	tag = lookup_tag(oid->hash);
	while (1) {
		if (!tag || parse_tag(tag) || !tag->tagged)
			die("unable to pack objects reachable from tag %s",
			    oid_to_hex(oid));

		add_object_entry(tag->object.oid.hash, OBJ_TAG, NULL, 0);

		if (tag->tagged->type != OBJ_TAG)
			return;

		tag = (struct tag *)tag->tagged;
	}
}

static int add_ref_tag(const char *path, const struct object_id *oid, int flag, void *cb_data)
{
	struct object_id peeled;

	if (starts_with(path, "refs/tags/") && /* is a tag? */
	    !peel_ref(path, peeled.hash)    && /* peelable? */
	    packlist_find(&to_pack, peeled.hash, NULL))      /* object packed? */
		add_tag_chain(oid);
	return 0;
}

static void prepare_pack(int window, int depth)
{
	struct object_entry **delta_list;
	uint32_t i, nr_deltas;
	unsigned n;

	get_object_details();

	/*
	 * If we're locally repacking then we need to be doubly careful
	 * from now on in order to make sure no stealth corruption gets
	 * propagated to the new pack.  Clients receiving streamed packs
	 * should validate everything they get anyway so no need to incur
	 * the additional cost here in that case.
	 */
	if (!pack_to_stdout)
		do_check_packed_object_crc = 1;

	if (!to_pack.nr_objects || !window || !depth)
		return;

	ALLOC_ARRAY(delta_list, to_pack.nr_objects);
	nr_deltas = n = 0;

	for (i = 0; i < to_pack.nr_objects; i++) {
		struct object_entry *entry = to_pack.objects + i;

		if (entry->delta)
			/* This happens if we decided to reuse existing
			 * delta from a pack.  "reuse_delta &&" is implied.
			 */
			continue;

		if (entry->size < 50)
			continue;

		if (entry->no_try_delta)
			continue;

		if (!entry->preferred_base) {
			nr_deltas++;
			if (entry->type < 0)
				die("unable to get type of object %s",
				    sha1_to_hex(entry->idx.sha1));
		} else {
			if (entry->type < 0) {
				/*
				 * This object is not found, but we
				 * don't have to include it anyway.
				 */
				continue;
			}
		}

		delta_list[n++] = entry;
	}

	if (nr_deltas && n > 1) {
		unsigned nr_done = 0;
		if (progress)
			progress_state = start_progress(_("Compressing objects"),
							nr_deltas);
		QSORT(delta_list, n, type_size_sort);
		ll_find_deltas(delta_list, n, window+1, depth, &nr_done);
		stop_progress(&progress_state);
		if (nr_done != nr_deltas)
			die("inconsistency with delta count");
	}
	free(delta_list);
}

static int git_pack_config(const char *k, const char *v, void *cb)
{
	if (!strcmp(k, "pack.window")) {
		window = git_config_int(k, v);
		return 0;
	}
	if (!strcmp(k, "pack.windowmemory")) {
		window_memory_limit = git_config_ulong(k, v);
		return 0;
	}
	if (!strcmp(k, "pack.depth")) {
		depth = git_config_int(k, v);
		return 0;
	}
	if (!strcmp(k, "pack.deltacachesize")) {
		max_delta_cache_size = git_config_int(k, v);
		return 0;
	}
	if (!strcmp(k, "pack.deltacachelimit")) {
		cache_max_small_delta_size = git_config_int(k, v);
		return 0;
	}
	if (!strcmp(k, "pack.writebitmaphashcache")) {
		if (git_config_bool(k, v))
			write_bitmap_options |= BITMAP_OPT_HASH_CACHE;
		else
			write_bitmap_options &= ~BITMAP_OPT_HASH_CACHE;
	}
	if (!strcmp(k, "pack.usebitmaps")) {
		use_bitmap_index_default = git_config_bool(k, v);
		return 0;
	}
	if (!strcmp(k, "pack.threads")) {
		delta_search_threads = git_config_int(k, v);
		if (delta_search_threads < 0)
			die("invalid number of threads specified (%d)",
			    delta_search_threads);
#ifdef NO_PTHREADS
		if (delta_search_threads != 1)
			warning("no threads support, ignoring %s", k);
#endif
		return 0;
	}
	if (!strcmp(k, "pack.indexversion")) {
		pack_idx_opts.version = git_config_int(k, v);
		if (pack_idx_opts.version > 2)
			die("bad pack.indexversion=%"PRIu32,
			    pack_idx_opts.version);
		return 0;
	}
	return git_default_config(k, v, cb);
}

static void read_object_list_from_stdin(void)
{
	char line[40 + 1 + PATH_MAX + 2];
	unsigned char sha1[20];

	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_errno("fgets");
			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);

		add_preferred_base_object(line+41);
		add_object_entry(sha1, 0, line+41, 0);
	}
}

#define OBJECT_ADDED (1u<<20)

static void show_commit(struct commit *commit, void *data)
{
	add_object_entry(commit->object.oid.hash, OBJ_COMMIT, NULL, 0);
	commit->object.flags |= OBJECT_ADDED;

	if (write_bitmap_index)
		index_commit_for_bitmap(commit);
}

static void show_object(struct object *obj, const char *name, void *data)
{
	add_preferred_base_object(name);
	add_object_entry(obj->oid.hash, obj->type, name, 0);
	obj->flags |= OBJECT_ADDED;
}

static void show_edge(struct commit *commit)
{
	add_preferred_base(commit->object.oid.hash);
}

struct in_pack_object {
	off_t offset;
	struct object *object;
};

struct in_pack {
	int alloc;
	int nr;
	struct in_pack_object *array;
};

static void mark_in_pack_object(struct object *object, struct packed_git *p, struct in_pack *in_pack)
{
	in_pack->array[in_pack->nr].offset = find_pack_entry_one(object->oid.hash, p);
	in_pack->array[in_pack->nr].object = object;
	in_pack->nr++;
}

/*
 * Compare the objects in the offset order, in order to emulate the
 * "git rev-list --objects" output that produced the pack originally.
 */
static int ofscmp(const void *a_, const void *b_)
{
	struct in_pack_object *a = (struct in_pack_object *)a_;
	struct in_pack_object *b = (struct in_pack_object *)b_;

	if (a->offset < b->offset)
		return -1;
	else if (a->offset > b->offset)
		return 1;
	else
		return oidcmp(&a->object->oid, &b->object->oid);
}

static void add_objects_in_unpacked_packs(struct rev_info *revs)
{
	struct packed_git *p;
	struct in_pack in_pack;
	uint32_t i;

	memset(&in_pack, 0, sizeof(in_pack));

	for (p = packed_git; p; p = p->next) {
		const unsigned char *sha1;
		struct object *o;

		if (!p->pack_local || p->pack_keep)
			continue;
		if (open_pack_index(p))
			die("cannot open pack index");

		ALLOC_GROW(in_pack.array,
			   in_pack.nr + p->num_objects,
			   in_pack.alloc);

		for (i = 0; i < p->num_objects; i++) {
			sha1 = nth_packed_object_sha1(p, i);
			o = lookup_unknown_object(sha1);
			if (!(o->flags & OBJECT_ADDED))
				mark_in_pack_object(o, p, &in_pack);
			o->flags |= OBJECT_ADDED;
		}
	}

	if (in_pack.nr) {
		QSORT(in_pack.array, in_pack.nr, ofscmp);
		for (i = 0; i < in_pack.nr; i++) {
			struct object *o = in_pack.array[i].object;
			add_object_entry(o->oid.hash, o->type, "", 0);
		}
	}
	free(in_pack.array);
}

static int add_loose_object(const unsigned char *sha1, const char *path,
			    void *data)
{
	enum object_type type = sha1_object_info(sha1, NULL);

	if (type < 0) {
		warning("loose object at %s could not be examined", path);
		return 0;
	}

	add_object_entry(sha1, type, "", 0);
	return 0;
}

/*
 * We actually don't even have to worry about reachability here.
 * add_object_entry will weed out duplicates, so we just add every
 * loose object we find.
 */
static void add_unreachable_loose_objects(void)
{
	for_each_loose_file_in_objdir(get_object_directory(),
				      add_loose_object,
				      NULL, NULL, NULL);
}

static int has_sha1_pack_kept_or_nonlocal(const unsigned char *sha1)
{
	static struct packed_git *last_found = (void *)1;
	struct packed_git *p;

	p = (last_found != (void *)1) ? last_found : packed_git;

	while (p) {
		if ((!p->pack_local || p->pack_keep) &&
			find_pack_entry_one(sha1, p)) {
			last_found = p;
			return 1;
		}
		if (p == last_found)
			p = packed_git;
		else
			p = p->next;
		if (p == last_found)
			p = p->next;
	}
	return 0;
}

/*
 * Store a list of sha1s that are should not be discarded
 * because they are either written too recently, or are
 * reachable from another object that was.
 *
 * This is filled by get_object_list.
 */
static struct sha1_array recent_objects;

static int loosened_object_can_be_discarded(const unsigned char *sha1,
					    unsigned long mtime)
{
	if (!unpack_unreachable_expiration)
		return 0;
	if (mtime > unpack_unreachable_expiration)
		return 0;
	if (sha1_array_lookup(&recent_objects, sha1) >= 0)
		return 0;
	return 1;
}

static void loosen_unused_packed_objects(struct rev_info *revs)
{
	struct packed_git *p;
	uint32_t i;
	const unsigned char *sha1;

	for (p = packed_git; p; p = p->next) {
		if (!p->pack_local || p->pack_keep)
			continue;

		if (open_pack_index(p))
			die("cannot open pack index");

		for (i = 0; i < p->num_objects; i++) {
			sha1 = nth_packed_object_sha1(p, i);
			if (!packlist_find(&to_pack, sha1, NULL) &&
			    !has_sha1_pack_kept_or_nonlocal(sha1) &&
			    !loosened_object_can_be_discarded(sha1, p->mtime))
				if (force_object_loose(sha1, p->mtime))
					die("unable to force loose object");
		}
	}
}

/*
 * This tracks any options which pack-reuse code expects to be on, or which a
 * reader of the pack might not understand, and which would therefore prevent
 * blind reuse of what we have on disk.
 */
static int pack_options_allow_reuse(void)
{
	return pack_to_stdout && allow_ofs_delta;
}

static int get_object_list_from_bitmap(struct rev_info *revs)
{
	if (prepare_bitmap_walk(revs) < 0)
		return -1;

	if (pack_options_allow_reuse() &&
	    !reuse_partial_packfile_from_bitmap(
			&reuse_packfile,
			&reuse_packfile_objects,
			&reuse_packfile_offset)) {
		assert(reuse_packfile_objects);
		nr_result += reuse_packfile_objects;
		display_progress(progress_state, nr_result);
	}

	traverse_bitmap_commit_list(&add_object_entry_from_bitmap);
	return 0;
}

static void record_recent_object(struct object *obj,
				 const char *name,
				 void *data)
{
	sha1_array_append(&recent_objects, obj->oid.hash);
}

static void record_recent_commit(struct commit *commit, void *data)
{
	sha1_array_append(&recent_objects, commit->object.oid.hash);
}

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;
	setup_revisions(ac, av, &revs, NULL);

	/* make sure shallows are read */
	is_repository_shallow();

	while (fgets(line, sizeof(line), stdin) != NULL) {
		int len = strlen(line);
		if (len && line[len - 1] == '\n')
			line[--len] = 0;
		if (!len)
			break;
		if (*line == '-') {
			if (!strcmp(line, "--not")) {
				flags ^= UNINTERESTING;
				write_bitmap_index = 0;
				continue;
			}
			if (starts_with(line, "--shallow ")) {
				unsigned char sha1[20];
				if (get_sha1_hex(line + 10, sha1))
					die("not an SHA-1 '%s'", line + 10);
				register_shallow(sha1);
				use_bitmap_index = 0;
				continue;
			}
			die("not a rev '%s'", line);
		}
		if (handle_revision_arg(line, &revs, flags, REVARG_CANNOT_BE_FILENAME))
			die("bad revision '%s'", line);
	}

	if (use_bitmap_index && !get_object_list_from_bitmap(&revs))
		return;

	if (prepare_revision_walk(&revs))
		die("revision walk setup failed");
	mark_edges_uninteresting(&revs, show_edge);
	traverse_commit_list(&revs, show_commit, show_object, NULL);

	if (unpack_unreachable_expiration) {
		revs.ignore_missing_links = 1;
		if (add_unseen_recent_objects_to_traversal(&revs,
				unpack_unreachable_expiration))
			die("unable to add recent objects");
		if (prepare_revision_walk(&revs))
			die("revision walk setup failed");
		traverse_commit_list(&revs, record_recent_commit,
				     record_recent_object, NULL);
	}

	if (keep_unreachable)
		add_objects_in_unpacked_packs(&revs);
	if (pack_loose_unreachable)
		add_unreachable_loose_objects();
	if (unpack_unreachable)
		loosen_unused_packed_objects(&revs);

	sha1_array_clear(&recent_objects);
}

static int option_parse_index_version(const struct option *opt,
				      const char *arg, int unset)
{
	char *c;
	const char *val = arg;
	pack_idx_opts.version = strtoul(val, &c, 10);
	if (pack_idx_opts.version > 2)
		die(_("unsupported index version %s"), val);
	if (*c == ',' && c[1])
		pack_idx_opts.off32_limit = strtoul(c+1, &c, 0);
	if (*c || pack_idx_opts.off32_limit & 0x80000000)
		die(_("bad index version '%s'"), val);
	return 0;
}

static int option_parse_unpack_unreachable(const struct option *opt,
					   const char *arg, int unset)
{
	if (unset) {
		unpack_unreachable = 0;
		unpack_unreachable_expiration = 0;
	}
	else {
		unpack_unreachable = 1;
		if (arg)
			unpack_unreachable_expiration = approxidate(arg);
	}
	return 0;
}

int cmd_pack_objects(int argc, const char **argv, const char *prefix)
{
	int use_internal_rev_list = 0;
	int thin = 0;
	int shallow = 0;
	int all_progress_implied = 0;
	struct argv_array rp = ARGV_ARRAY_INIT;
	int rev_list_unpacked = 0, rev_list_all = 0, rev_list_reflog = 0;
	int rev_list_index = 0;
	struct option pack_objects_options[] = {
		OPT_SET_INT('q', "quiet", &progress,
			    N_("do not show progress meter"), 0),
		OPT_SET_INT(0, "progress", &progress,
			    N_("show progress meter"), 1),
		OPT_SET_INT(0, "all-progress", &progress,
			    N_("show progress meter during object writing phase"), 2),
		OPT_BOOL(0, "all-progress-implied",
			 &all_progress_implied,
			 N_("similar to --all-progress when progress meter is shown")),
		{ OPTION_CALLBACK, 0, "index-version", NULL, N_("version[,offset]"),
		  N_("write the pack index file in the specified idx format version"),
		  0, option_parse_index_version },
		OPT_MAGNITUDE(0, "max-pack-size", &pack_size_limit,
			      N_("maximum size of each output pack file")),
		OPT_BOOL(0, "local", &local,
			 N_("ignore borrowed objects from alternate object store")),
		OPT_BOOL(0, "incremental", &incremental,
			 N_("ignore packed objects")),
		OPT_INTEGER(0, "window", &window,
			    N_("limit pack window by objects")),
		OPT_MAGNITUDE(0, "window-memory", &window_memory_limit,
			      N_("limit pack window by memory in addition to object limit")),
		OPT_INTEGER(0, "depth", &depth,
			    N_("maximum length of delta chain allowed in the resulting pack")),
		OPT_BOOL(0, "reuse-delta", &reuse_delta,
			 N_("reuse existing deltas")),
		OPT_BOOL(0, "reuse-object", &reuse_object,
			 N_("reuse existing objects")),
		OPT_BOOL(0, "delta-base-offset", &allow_ofs_delta,
			 N_("use OFS_DELTA objects")),
		OPT_INTEGER(0, "threads", &delta_search_threads,
			    N_("use threads when searching for best delta matches")),
		OPT_BOOL(0, "non-empty", &non_empty,
			 N_("do not create an empty pack output")),
		OPT_BOOL(0, "revs", &use_internal_rev_list,
			 N_("read revision arguments from standard input")),
		{ OPTION_SET_INT, 0, "unpacked", &rev_list_unpacked, NULL,
		  N_("limit the objects to those that are not yet packed"),
		  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
		{ OPTION_SET_INT, 0, "all", &rev_list_all, NULL,
		  N_("include objects reachable from any reference"),
		  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
		{ OPTION_SET_INT, 0, "reflog", &rev_list_reflog, NULL,
		  N_("include objects referred by reflog entries"),
		  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
		{ OPTION_SET_INT, 0, "indexed-objects", &rev_list_index, NULL,
		  N_("include objects referred to by the index"),
		  PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
		OPT_BOOL(0, "stdout", &pack_to_stdout,
			 N_("output pack to stdout")),
		OPT_BOOL(0, "include-tag", &include_tag,
			 N_("include tag objects that refer to objects to be packed")),
		OPT_BOOL(0, "keep-unreachable", &keep_unreachable,
			 N_("keep unreachable objects")),
		OPT_BOOL(0, "pack-loose-unreachable", &pack_loose_unreachable,
			 N_("pack loose unreachable objects")),
		{ OPTION_CALLBACK, 0, "unpack-unreachable", NULL, N_("time"),
		  N_("unpack unreachable objects newer than <time>"),
		  PARSE_OPT_OPTARG, option_parse_unpack_unreachable },
		OPT_BOOL(0, "thin", &thin,
			 N_("create thin packs")),
		OPT_BOOL(0, "shallow", &shallow,
			 N_("create packs suitable for shallow fetches")),
		OPT_BOOL(0, "honor-pack-keep", &ignore_packed_keep,
			 N_("ignore packs that have companion .keep file")),
		OPT_INTEGER(0, "compression", &pack_compression_level,
			    N_("pack compression level")),
		OPT_SET_INT(0, "keep-true-parents", &grafts_replace_parents,
			    N_("do not hide commits by grafts"), 0),
		OPT_BOOL(0, "use-bitmap-index", &use_bitmap_index,
			 N_("use a bitmap index if available to speed up counting objects")),
		OPT_BOOL(0, "write-bitmap-index", &write_bitmap_index,
			 N_("write a bitmap index together with the pack index")),
		OPT_END(),
	};

	check_replace_refs = 0;

	reset_pack_idx_option(&pack_idx_opts);
	git_config(git_pack_config, NULL);

	progress = isatty(2);
	argc = parse_options(argc, argv, prefix, pack_objects_options,
			     pack_usage, 0);

	if (argc) {
		base_name = argv[0];
		argc--;
	}
	if (pack_to_stdout != !base_name || argc)
		usage_with_options(pack_usage, pack_objects_options);

	argv_array_push(&rp, "pack-objects");
	if (thin) {
		use_internal_rev_list = 1;
		argv_array_push(&rp, shallow
				? "--objects-edge-aggressive"
				: "--objects-edge");
	} else
		argv_array_push(&rp, "--objects");

	if (rev_list_all) {
		use_internal_rev_list = 1;
		argv_array_push(&rp, "--all");
	}
	if (rev_list_reflog) {
		use_internal_rev_list = 1;
		argv_array_push(&rp, "--reflog");
	}
	if (rev_list_index) {
		use_internal_rev_list = 1;
		argv_array_push(&rp, "--indexed-objects");
	}
	if (rev_list_unpacked) {
		use_internal_rev_list = 1;
		argv_array_push(&rp, "--unpacked");
	}

	if (!reuse_object)
		reuse_delta = 0;
	if (pack_compression_level == -1)
		pack_compression_level = Z_DEFAULT_COMPRESSION;
	else if (pack_compression_level < 0 || pack_compression_level > Z_BEST_COMPRESSION)
		die("bad pack compression level %d", pack_compression_level);

	if (!delta_search_threads)	/* --threads=0 means autodetect */
		delta_search_threads = online_cpus();

#ifdef NO_PTHREADS
	if (delta_search_threads != 1)
		warning("no threads support, ignoring --threads");
#endif
	if (!pack_to_stdout && !pack_size_limit)
		pack_size_limit = pack_size_limit_cfg;
	if (pack_to_stdout && pack_size_limit)
		die("--max-pack-size cannot be used to build a pack for transfer.");
	if (pack_size_limit && pack_size_limit < 1024*1024) {
		warning("minimum pack size limit is 1 MiB");
		pack_size_limit = 1024*1024;
	}

	if (!pack_to_stdout && thin)
		die("--thin cannot be used to build an indexable pack.");

	if (keep_unreachable && unpack_unreachable)
		die("--keep-unreachable and --unpack-unreachable are incompatible.");
	if (!rev_list_all || !rev_list_reflog || !rev_list_index)
		unpack_unreachable_expiration = 0;

	/*
	 * "soft" reasons not to use bitmaps - for on-disk repack by default we want
	 *
	 * - to produce good pack (with bitmap index not-yet-packed objects are
	 *   packed in suboptimal order).
	 *
	 * - to use more robust pack-generation codepath (avoiding possible
	 *   bugs in bitmap code and possible bitmap index corruption).
	 */
	if (!pack_to_stdout)
		use_bitmap_index_default = 0;

	if (use_bitmap_index < 0)
		use_bitmap_index = use_bitmap_index_default;

	/* "hard" reasons not to use bitmaps; these just won't work at all */
	if (!use_internal_rev_list || (!pack_to_stdout && write_bitmap_index) || is_repository_shallow())
		use_bitmap_index = 0;

	if (pack_to_stdout || !rev_list_all)
		write_bitmap_index = 0;

	if (progress && all_progress_implied)
		progress = 2;

	prepare_packed_git();
	if (ignore_packed_keep) {
		struct packed_git *p;
		for (p = packed_git; p; p = p->next)
			if (p->pack_local && p->pack_keep)
				break;
		if (!p) /* no keep-able packs found */
			ignore_packed_keep = 0;
	}
	if (local) {
		/*
		 * unlike ignore_packed_keep above, we do not want to
		 * unset "local" based on looking at packs, as it
		 * also covers non-local objects
		 */
		struct packed_git *p;
		for (p = packed_git; p; p = p->next) {
			if (!p->pack_local) {
				have_non_local_packs = 1;
				break;
			}
		}
	}

	if (progress)
		progress_state = start_progress(_("Counting objects"), 0);
	if (!use_internal_rev_list)
		read_object_list_from_stdin();
	else {
		get_object_list(rp.argc, rp.argv);
		argv_array_clear(&rp);
	}
	cleanup_preferred_base();
	if (include_tag && nr_result)
		for_each_ref(add_ref_tag, NULL);
	stop_progress(&progress_state);

	if (non_empty && !nr_result)
		return 0;
	if (nr_result)
		prepare_pack(window, depth);
	write_pack_file();
	if (progress)
		fprintf(stderr, "Total %"PRIu32" (delta %"PRIu32"),"
			" reused %"PRIu32" (delta %"PRIu32")\n",
			written, written_delta, reused, reused_delta);
	return 0;
}