about summary refs log tree commit diff
path: root/vendor/golang.org/x/sys/unix/syscall_linux.go
blob: 3f1d3d4cb2560b171bd7414fb6cbe6abcac17df6 (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
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Linux system calls.
// This file is compiled as ordinary Go code,
// but it is also input to mksyscall,
// which parses the //sys lines and generates system call stubs.
// Note that sometimes we use a lowercase //sys name and
// wrap it in our own nicer implementation.

package unix

import (
	"encoding/binary"
	"strconv"
	"syscall"
	"time"
	"unsafe"
)

/*
 * Wrapped
 */

func Access(path string, mode uint32) (err error) {
	return Faccessat(AT_FDCWD, path, mode, 0)
}

func Chmod(path string, mode uint32) (err error) {
	return Fchmodat(AT_FDCWD, path, mode, 0)
}

func Chown(path string, uid int, gid int) (err error) {
	return Fchownat(AT_FDCWD, path, uid, gid, 0)
}

func Creat(path string, mode uint32) (fd int, err error) {
	return Open(path, O_CREAT|O_WRONLY|O_TRUNC, mode)
}

func EpollCreate(size int) (fd int, err error) {
	if size <= 0 {
		return -1, EINVAL
	}
	return EpollCreate1(0)
}

//sys	FanotifyInit(flags uint, event_f_flags uint) (fd int, err error)
//sys	fanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname *byte) (err error)

func FanotifyMark(fd int, flags uint, mask uint64, dirFd int, pathname string) (err error) {
	if pathname == "" {
		return fanotifyMark(fd, flags, mask, dirFd, nil)
	}
	p, err := BytePtrFromString(pathname)
	if err != nil {
		return err
	}
	return fanotifyMark(fd, flags, mask, dirFd, p)
}

//sys	fchmodat(dirfd int, path string, mode uint32) (err error)
//sys	fchmodat2(dirfd int, path string, mode uint32, flags int) (err error)

func Fchmodat(dirfd int, path string, mode uint32, flags int) error {
	// Linux fchmodat doesn't support the flags parameter, but fchmodat2 does.
	// Try fchmodat2 if flags are specified.
	if flags != 0 {
		err := fchmodat2(dirfd, path, mode, flags)
		if err == ENOSYS {
			// fchmodat2 isn't available. If the flags are known to be valid,
			// return EOPNOTSUPP to indicate that fchmodat doesn't support them.
			if flags&^(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH) != 0 {
				return EINVAL
			} else if flags&(AT_SYMLINK_NOFOLLOW|AT_EMPTY_PATH) != 0 {
				return EOPNOTSUPP
			}
		}
		return err
	}
	return fchmodat(dirfd, path, mode)
}

func InotifyInit() (fd int, err error) {
	return InotifyInit1(0)
}

//sys	ioctl(fd int, req uint, arg uintptr) (err error) = SYS_IOCTL
//sys	ioctlPtr(fd int, req uint, arg unsafe.Pointer) (err error) = SYS_IOCTL

// ioctl itself should not be exposed directly, but additional get/set functions
// for specific types are permissible. These are defined in ioctl.go and
// ioctl_linux.go.
//
// The third argument to ioctl is often a pointer but sometimes an integer.
// Callers should use ioctlPtr when the third argument is a pointer and ioctl
// when the third argument is an integer.
//
// TODO: some existing code incorrectly uses ioctl when it should use ioctlPtr.

//sys	Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)

func Link(oldpath string, newpath string) (err error) {
	return Linkat(AT_FDCWD, oldpath, AT_FDCWD, newpath, 0)
}

func Mkdir(path string, mode uint32) (err error) {
	return Mkdirat(AT_FDCWD, path, mode)
}

func Mknod(path string, mode uint32, dev int) (err error) {
	return Mknodat(AT_FDCWD, path, mode, dev)
}

func Open(path string, mode int, perm uint32) (fd int, err error) {
	return openat(AT_FDCWD, path, mode|O_LARGEFILE, perm)
}

//sys	openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)

func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
	return openat(dirfd, path, flags|O_LARGEFILE, mode)
}

//sys	openat2(dirfd int, path string, open_how *OpenHow, size int) (fd int, err error)

func Openat2(dirfd int, path string, how *OpenHow) (fd int, err error) {
	return openat2(dirfd, path, how, SizeofOpenHow)
}

func Pipe(p []int) error {
	return Pipe2(p, 0)
}

//sysnb	pipe2(p *[2]_C_int, flags int) (err error)

func Pipe2(p []int, flags int) error {
	if len(p) != 2 {
		return EINVAL
	}
	var pp [2]_C_int
	err := pipe2(&pp, flags)
	if err == nil {
		p[0] = int(pp[0])
		p[1] = int(pp[1])
	}
	return err
}

//sys	ppoll(fds *PollFd, nfds int, timeout *Timespec, sigmask *Sigset_t) (n int, err error)

func Ppoll(fds []PollFd, timeout *Timespec, sigmask *Sigset_t) (n int, err error) {
	if len(fds) == 0 {
		return ppoll(nil, 0, timeout, sigmask)
	}
	return ppoll(&fds[0], len(fds), timeout, sigmask)
}

func Poll(fds []PollFd, timeout int) (n int, err error) {
	var ts *Timespec
	if timeout >= 0 {
		ts = new(Timespec)
		*ts = NsecToTimespec(int64(timeout) * 1e6)
	}
	return Ppoll(fds, ts, nil)
}

//sys	Readlinkat(dirfd int, path string, buf []byte) (n int, err error)

func Readlink(path string, buf []byte) (n int, err error) {
	return Readlinkat(AT_FDCWD, path, buf)
}

func Rename(oldpath string, newpath string) (err error) {
	return Renameat(AT_FDCWD, oldpath, AT_FDCWD, newpath)
}

func Rmdir(path string) error {
	return Unlinkat(AT_FDCWD, path, AT_REMOVEDIR)
}

//sys	Symlinkat(oldpath string, newdirfd int, newpath string) (err error)

func Symlink(oldpath string, newpath string) (err error) {
	return Symlinkat(oldpath, AT_FDCWD, newpath)
}

func Unlink(path string) error {
	return Unlinkat(AT_FDCWD, path, 0)
}

//sys	Unlinkat(dirfd int, path string, flags int) (err error)

func Utimes(path string, tv []Timeval) error {
	if tv == nil {
		err := utimensat(AT_FDCWD, path, nil, 0)
		if err != ENOSYS {
			return err
		}
		return utimes(path, nil)
	}
	if len(tv) != 2 {
		return EINVAL
	}
	var ts [2]Timespec
	ts[0] = NsecToTimespec(TimevalToNsec(tv[0]))
	ts[1] = NsecToTimespec(TimevalToNsec(tv[1]))
	err := utimensat(AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
	if err != ENOSYS {
		return err
	}
	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
}

//sys	utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)

func UtimesNano(path string, ts []Timespec) error {
	return UtimesNanoAt(AT_FDCWD, path, ts, 0)
}

func UtimesNanoAt(dirfd int, path string, ts []Timespec, flags int) error {
	if ts == nil {
		return utimensat(dirfd, path, nil, flags)
	}
	if len(ts) != 2 {
		return EINVAL
	}
	return utimensat(dirfd, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), flags)
}

func Futimesat(dirfd int, path string, tv []Timeval) error {
	if tv == nil {
		return futimesat(dirfd, path, nil)
	}
	if len(tv) != 2 {
		return EINVAL
	}
	return futimesat(dirfd, path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
}

func Futimes(fd int, tv []Timeval) (err error) {
	// Believe it or not, this is the best we can do on Linux
	// (and is what glibc does).
	return Utimes("/proc/self/fd/"+strconv.Itoa(fd), tv)
}

const ImplementsGetwd = true

//sys	Getcwd(buf []byte) (n int, err error)

func Getwd() (wd string, err error) {
	var buf [PathMax]byte
	n, err := Getcwd(buf[0:])
	if err != nil {
		return "", err
	}
	// Getcwd returns the number of bytes written to buf, including the NUL.
	if n < 1 || n > len(buf) || buf[n-1] != 0 {
		return "", EINVAL
	}
	// In some cases, Linux can return a path that starts with the
	// "(unreachable)" prefix, which can potentially be a valid relative
	// path. To work around that, return ENOENT if path is not absolute.
	if buf[0] != '/' {
		return "", ENOENT
	}

	return string(buf[0 : n-1]), nil
}

func Getgroups() (gids []int, err error) {
	n, err := getgroups(0, nil)
	if err != nil {
		return nil, err
	}
	if n == 0 {
		return nil, nil
	}

	// Sanity check group count. Max is 1<<16 on Linux.
	if n < 0 || n > 1<<20 {
		return nil, EINVAL
	}

	a := make([]_Gid_t, n)
	n, err = getgroups(n, &a[0])
	if err != nil {
		return nil, err
	}
	gids = make([]int, n)
	for i, v := range a[0:n] {
		gids[i] = int(v)
	}
	return
}

func Setgroups(gids []int) (err error) {
	if len(gids) == 0 {
		return setgroups(0, nil)
	}

	a := make([]_Gid_t, len(gids))
	for i, v := range gids {
		a[i] = _Gid_t(v)
	}
	return setgroups(len(a), &a[0])
}

type WaitStatus uint32

// Wait status is 7 bits at bottom, either 0 (exited),
// 0x7F (stopped), or a signal number that caused an exit.
// The 0x80 bit is whether there was a core dump.
// An extra number (exit code, signal causing a stop)
// is in the high bits. At least that's the idea.
// There are various irregularities. For example, the
// "continued" status is 0xFFFF, distinguishing itself
// from stopped via the core dump bit.

const (
	mask    = 0x7F
	core    = 0x80
	exited  = 0x00
	stopped = 0x7F
	shift   = 8
)

func (w WaitStatus) Exited() bool { return w&mask == exited }

func (w WaitStatus) Signaled() bool { return w&mask != stopped && w&mask != exited }

func (w WaitStatus) Stopped() bool { return w&0xFF == stopped }

func (w WaitStatus) Continued() bool { return w == 0xFFFF }

func (w WaitStatus) CoreDump() bool { return w.Signaled() && w&core != 0 }

func (w WaitStatus) ExitStatus() int {
	if !w.Exited() {
		return -1
	}
	return int(w>>shift) & 0xFF
}

func (w WaitStatus) Signal() syscall.Signal {
	if !w.Signaled() {
		return -1
	}
	return syscall.Signal(w & mask)
}

func (w WaitStatus) StopSignal() syscall.Signal {
	if !w.Stopped() {
		return -1
	}
	return syscall.Signal(w>>shift) & 0xFF
}

func (w WaitStatus) TrapCause() int {
	if w.StopSignal() != SIGTRAP {
		return -1
	}
	return int(w>>shift) >> 8
}

//sys	wait4(pid int, wstatus *_C_int, options int, rusage *Rusage) (wpid int, err error)

func Wait4(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error) {
	var status _C_int
	wpid, err = wait4(pid, &status, options, rusage)
	if wstatus != nil {
		*wstatus = WaitStatus(status)
	}
	return
}

//sys	Waitid(idType int, id int, info *Siginfo, options int, rusage *Rusage) (err error)

func Mkfifo(path string, mode uint32) error {
	return Mknod(path, mode|S_IFIFO, 0)
}

func Mkfifoat(dirfd int, path string, mode uint32) error {
	return Mknodat(dirfd, path, mode|S_IFIFO, 0)
}

func (sa *SockaddrInet4) sockaddr() (unsafe.Pointer, _Socklen, error) {
	if sa.Port < 0 || sa.Port > 0xFFFF {
		return nil, 0, EINVAL
	}
	sa.raw.Family = AF_INET
	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
	p[0] = byte(sa.Port >> 8)
	p[1] = byte(sa.Port)
	sa.raw.Addr = sa.Addr
	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet4, nil
}

func (sa *SockaddrInet6) sockaddr() (unsafe.Pointer, _Socklen, error) {
	if sa.Port < 0 || sa.Port > 0xFFFF {
		return nil, 0, EINVAL
	}
	sa.raw.Family = AF_INET6
	p := (*[2]byte)(unsafe.Pointer(&sa.raw.Port))
	p[0] = byte(sa.Port >> 8)
	p[1] = byte(sa.Port)
	sa.raw.Scope_id = sa.ZoneId
	sa.raw.Addr = sa.Addr
	return unsafe.Pointer(&sa.raw), SizeofSockaddrInet6, nil
}

func (sa *SockaddrUnix) sockaddr() (unsafe.Pointer, _Socklen, error) {
	name := sa.Name
	n := len(name)
	if n >= len(sa.raw.Path) {
		return nil, 0, EINVAL
	}
	sa.raw.Family = AF_UNIX
	for i := 0; i < n; i++ {
		sa.raw.Path[i] = int8(name[i])
	}
	// length is family (uint16), name, NUL.
	sl := _Socklen(2)
	if n > 0 {
		sl += _Socklen(n) + 1
	}
	if sa.raw.Path[0] == '@' || (sa.raw.Path[0] == 0 && sl > 3) {
		// Check sl > 3 so we don't change unnamed socket behavior.
		sa.raw.Path[0] = 0
		// Don't count trailing NUL for abstract address.
		sl--
	}

	return unsafe.Pointer(&sa.raw), sl, nil
}

// SockaddrLinklayer implements the Sockaddr interface for AF_PACKET type sockets.
type SockaddrLinklayer struct {
	Protocol uint16
	Ifindex  int
	Hatype   uint16
	Pkttype  uint8
	Halen    uint8
	Addr     [8]byte
	raw      RawSockaddrLinklayer
}

func (sa *SockaddrLinklayer) sockaddr() (unsafe.Pointer, _Socklen, error) {
	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
		return nil, 0, EINVAL
	}
	sa.raw.Family = AF_PACKET
	sa.raw.Protocol = sa.Protocol
	sa.raw.Ifindex = int32(sa.Ifindex)
	sa.raw.Hatype = sa.Hatype
	sa.raw.Pkttype = sa.Pkttype
	sa.raw.Halen = sa.Halen
	sa.raw.Addr = sa.Addr
	return unsafe.Pointer(&sa.raw), SizeofSockaddrLinklayer, nil
}

// SockaddrNetlink implements the Sockaddr interface for AF_NETLINK type sockets.
type SockaddrNetlink struct {
	Family uint16
	Pad    uint16
	Pid    uint32
	Groups uint32
	raw    RawSockaddrNetlink
}

func (sa *SockaddrNetlink) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_NETLINK
	sa.raw.Pad = sa.Pad
	sa.raw.Pid = sa.Pid
	sa.raw.Groups = sa.Groups
	return unsafe.Pointer(&sa.raw), SizeofSockaddrNetlink, nil
}

// SockaddrHCI implements the Sockaddr interface for AF_BLUETOOTH type sockets
// using the HCI protocol.
type SockaddrHCI struct {
	Dev     uint16
	Channel uint16
	raw     RawSockaddrHCI
}

func (sa *SockaddrHCI) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_BLUETOOTH
	sa.raw.Dev = sa.Dev
	sa.raw.Channel = sa.Channel
	return unsafe.Pointer(&sa.raw), SizeofSockaddrHCI, nil
}

// SockaddrL2 implements the Sockaddr interface for AF_BLUETOOTH type sockets
// using the L2CAP protocol.
type SockaddrL2 struct {
	PSM      uint16
	CID      uint16
	Addr     [6]uint8
	AddrType uint8
	raw      RawSockaddrL2
}

func (sa *SockaddrL2) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_BLUETOOTH
	psm := (*[2]byte)(unsafe.Pointer(&sa.raw.Psm))
	psm[0] = byte(sa.PSM)
	psm[1] = byte(sa.PSM >> 8)
	for i := 0; i < len(sa.Addr); i++ {
		sa.raw.Bdaddr[i] = sa.Addr[len(sa.Addr)-1-i]
	}
	cid := (*[2]byte)(unsafe.Pointer(&sa.raw.Cid))
	cid[0] = byte(sa.CID)
	cid[1] = byte(sa.CID >> 8)
	sa.raw.Bdaddr_type = sa.AddrType
	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2, nil
}

// SockaddrRFCOMM implements the Sockaddr interface for AF_BLUETOOTH type sockets
// using the RFCOMM protocol.
//
// Server example:
//
//	fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
//	_ = unix.Bind(fd, &unix.SockaddrRFCOMM{
//		Channel: 1,
//		Addr:    [6]uint8{0, 0, 0, 0, 0, 0}, // BDADDR_ANY or 00:00:00:00:00:00
//	})
//	_ = Listen(fd, 1)
//	nfd, sa, _ := Accept(fd)
//	fmt.Printf("conn addr=%v fd=%d", sa.(*unix.SockaddrRFCOMM).Addr, nfd)
//	Read(nfd, buf)
//
// Client example:
//
//	fd, _ := Socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)
//	_ = Connect(fd, &SockaddrRFCOMM{
//		Channel: 1,
//		Addr:    [6]byte{0x11, 0x22, 0x33, 0xaa, 0xbb, 0xcc}, // CC:BB:AA:33:22:11
//	})
//	Write(fd, []byte(`hello`))
type SockaddrRFCOMM struct {
	// Addr represents a bluetooth address, byte ordering is little-endian.
	Addr [6]uint8

	// Channel is a designated bluetooth channel, only 1-30 are available for use.
	// Since Linux 2.6.7 and further zero value is the first available channel.
	Channel uint8

	raw RawSockaddrRFCOMM
}

func (sa *SockaddrRFCOMM) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_BLUETOOTH
	sa.raw.Channel = sa.Channel
	sa.raw.Bdaddr = sa.Addr
	return unsafe.Pointer(&sa.raw), SizeofSockaddrRFCOMM, nil
}

// SockaddrCAN implements the Sockaddr interface for AF_CAN type sockets.
// The RxID and TxID fields are used for transport protocol addressing in
// (CAN_TP16, CAN_TP20, CAN_MCNET, and CAN_ISOTP), they can be left with
// zero values for CAN_RAW and CAN_BCM sockets as they have no meaning.
//
// The SockaddrCAN struct must be bound to the socket file descriptor
// using Bind before the CAN socket can be used.
//
//	// Read one raw CAN frame
//	fd, _ := Socket(AF_CAN, SOCK_RAW, CAN_RAW)
//	addr := &SockaddrCAN{Ifindex: index}
//	Bind(fd, addr)
//	frame := make([]byte, 16)
//	Read(fd, frame)
//
// The full SocketCAN documentation can be found in the linux kernel
// archives at: https://www.kernel.org/doc/Documentation/networking/can.txt
type SockaddrCAN struct {
	Ifindex int
	RxID    uint32
	TxID    uint32
	raw     RawSockaddrCAN
}

func (sa *SockaddrCAN) sockaddr() (unsafe.Pointer, _Socklen, error) {
	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
		return nil, 0, EINVAL
	}
	sa.raw.Family = AF_CAN
	sa.raw.Ifindex = int32(sa.Ifindex)
	rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
	for i := 0; i < 4; i++ {
		sa.raw.Addr[i] = rx[i]
	}
	tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
	for i := 0; i < 4; i++ {
		sa.raw.Addr[i+4] = tx[i]
	}
	return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
}

// SockaddrCANJ1939 implements the Sockaddr interface for AF_CAN using J1939
// protocol (https://en.wikipedia.org/wiki/SAE_J1939). For more information
// on the purposes of the fields, check the official linux kernel documentation
// available here: https://www.kernel.org/doc/Documentation/networking/j1939.rst
type SockaddrCANJ1939 struct {
	Ifindex int
	Name    uint64
	PGN     uint32
	Addr    uint8
	raw     RawSockaddrCAN
}

func (sa *SockaddrCANJ1939) sockaddr() (unsafe.Pointer, _Socklen, error) {
	if sa.Ifindex < 0 || sa.Ifindex > 0x7fffffff {
		return nil, 0, EINVAL
	}
	sa.raw.Family = AF_CAN
	sa.raw.Ifindex = int32(sa.Ifindex)
	n := (*[8]byte)(unsafe.Pointer(&sa.Name))
	for i := 0; i < 8; i++ {
		sa.raw.Addr[i] = n[i]
	}
	p := (*[4]byte)(unsafe.Pointer(&sa.PGN))
	for i := 0; i < 4; i++ {
		sa.raw.Addr[i+8] = p[i]
	}
	sa.raw.Addr[12] = sa.Addr
	return unsafe.Pointer(&sa.raw), SizeofSockaddrCAN, nil
}

// SockaddrALG implements the Sockaddr interface for AF_ALG type sockets.
// SockaddrALG enables userspace access to the Linux kernel's cryptography
// subsystem. The Type and Name fields specify which type of hash or cipher
// should be used with a given socket.
//
// To create a file descriptor that provides access to a hash or cipher, both
// Bind and Accept must be used. Once the setup process is complete, input
// data can be written to the socket, processed by the kernel, and then read
// back as hash output or ciphertext.
//
// Here is an example of using an AF_ALG socket with SHA1 hashing.
// The initial socket setup process is as follows:
//
//	// Open a socket to perform SHA1 hashing.
//	fd, _ := unix.Socket(unix.AF_ALG, unix.SOCK_SEQPACKET, 0)
//	addr := &unix.SockaddrALG{Type: "hash", Name: "sha1"}
//	unix.Bind(fd, addr)
//	// Note: unix.Accept does not work at this time; must invoke accept()
//	// manually using unix.Syscall.
//	hashfd, _, _ := unix.Syscall(unix.SYS_ACCEPT, uintptr(fd), 0, 0)
//
// Once a file descriptor has been returned from Accept, it may be used to
// perform SHA1 hashing. The descriptor is not safe for concurrent use, but
// may be re-used repeatedly with subsequent Write and Read operations.
//
// When hashing a small byte slice or string, a single Write and Read may
// be used:
//
//	// Assume hashfd is already configured using the setup process.
//	hash := os.NewFile(hashfd, "sha1")
//	// Hash an input string and read the results. Each Write discards
//	// previous hash state. Read always reads the current state.
//	b := make([]byte, 20)
//	for i := 0; i < 2; i++ {
//	    io.WriteString(hash, "Hello, world.")
//	    hash.Read(b)
//	    fmt.Println(hex.EncodeToString(b))
//	}
//	// Output:
//	// 2ae01472317d1935a84797ec1983ae243fc6aa28
//	// 2ae01472317d1935a84797ec1983ae243fc6aa28
//
// For hashing larger byte slices, or byte streams such as those read from
// a file or socket, use Sendto with MSG_MORE to instruct the kernel to update
// the hash digest instead of creating a new one for a given chunk and finalizing it.
//
//	// Assume hashfd and addr are already configured using the setup process.
//	hash := os.NewFile(hashfd, "sha1")
//	// Hash the contents of a file.
//	f, _ := os.Open("/tmp/linux-4.10-rc7.tar.xz")
//	b := make([]byte, 4096)
//	for {
//	    n, err := f.Read(b)
//	    if err == io.EOF {
//	        break
//	    }
//	    unix.Sendto(hashfd, b[:n], unix.MSG_MORE, addr)
//	}
//	hash.Read(b)
//	fmt.Println(hex.EncodeToString(b))
//	// Output: 85cdcad0c06eef66f805ecce353bec9accbeecc5
//
// For more information, see: http://www.chronox.de/crypto-API/crypto/userspace-if.html.
type SockaddrALG struct {
	Type    string
	Name    string
	Feature uint32
	Mask    uint32
	raw     RawSockaddrALG
}

func (sa *SockaddrALG) sockaddr() (unsafe.Pointer, _Socklen, error) {
	// Leave room for NUL byte terminator.
	if len(sa.Type) > len(sa.raw.Type)-1 {
		return nil, 0, EINVAL
	}
	if len(sa.Name) > len(sa.raw.Name)-1 {
		return nil, 0, EINVAL
	}

	sa.raw.Family = AF_ALG
	sa.raw.Feat = sa.Feature
	sa.raw.Mask = sa.Mask

	copy(sa.raw.Type[:], sa.Type)
	copy(sa.raw.Name[:], sa.Name)

	return unsafe.Pointer(&sa.raw), SizeofSockaddrALG, nil
}

// SockaddrVM implements the Sockaddr interface for AF_VSOCK type sockets.
// SockaddrVM provides access to Linux VM sockets: a mechanism that enables
// bidirectional communication between a hypervisor and its guest virtual
// machines.
type SockaddrVM struct {
	// CID and Port specify a context ID and port address for a VM socket.
	// Guests have a unique CID, and hosts may have a well-known CID of:
	//  - VMADDR_CID_HYPERVISOR: refers to the hypervisor process.
	//  - VMADDR_CID_LOCAL: refers to local communication (loopback).
	//  - VMADDR_CID_HOST: refers to other processes on the host.
	CID   uint32
	Port  uint32
	Flags uint8
	raw   RawSockaddrVM
}

func (sa *SockaddrVM) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_VSOCK
	sa.raw.Port = sa.Port
	sa.raw.Cid = sa.CID
	sa.raw.Flags = sa.Flags

	return unsafe.Pointer(&sa.raw), SizeofSockaddrVM, nil
}

type SockaddrXDP struct {
	Flags        uint16
	Ifindex      uint32
	QueueID      uint32
	SharedUmemFD uint32
	raw          RawSockaddrXDP
}

func (sa *SockaddrXDP) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_XDP
	sa.raw.Flags = sa.Flags
	sa.raw.Ifindex = sa.Ifindex
	sa.raw.Queue_id = sa.QueueID
	sa.raw.Shared_umem_fd = sa.SharedUmemFD

	return unsafe.Pointer(&sa.raw), SizeofSockaddrXDP, nil
}

// This constant mirrors the #define of PX_PROTO_OE in
// linux/if_pppox.h. We're defining this by hand here instead of
// autogenerating through mkerrors.sh because including
// linux/if_pppox.h causes some declaration conflicts with other
// includes (linux/if_pppox.h includes linux/in.h, which conflicts
// with netinet/in.h). Given that we only need a single zero constant
// out of that file, it's cleaner to just define it by hand here.
const px_proto_oe = 0

type SockaddrPPPoE struct {
	SID    uint16
	Remote []byte
	Dev    string
	raw    RawSockaddrPPPoX
}

func (sa *SockaddrPPPoE) sockaddr() (unsafe.Pointer, _Socklen, error) {
	if len(sa.Remote) != 6 {
		return nil, 0, EINVAL
	}
	if len(sa.Dev) > IFNAMSIZ-1 {
		return nil, 0, EINVAL
	}

	*(*uint16)(unsafe.Pointer(&sa.raw[0])) = AF_PPPOX
	// This next field is in host-endian byte order. We can't use the
	// same unsafe pointer cast as above, because this value is not
	// 32-bit aligned and some architectures don't allow unaligned
	// access.
	//
	// However, the value of px_proto_oe is 0, so we can use
	// encoding/binary helpers to write the bytes without worrying
	// about the ordering.
	binary.BigEndian.PutUint32(sa.raw[2:6], px_proto_oe)
	// This field is deliberately big-endian, unlike the previous
	// one. The kernel expects SID to be in network byte order.
	binary.BigEndian.PutUint16(sa.raw[6:8], sa.SID)
	copy(sa.raw[8:14], sa.Remote)
	for i := 14; i < 14+IFNAMSIZ; i++ {
		sa.raw[i] = 0
	}
	copy(sa.raw[14:], sa.Dev)
	return unsafe.Pointer(&sa.raw), SizeofSockaddrPPPoX, nil
}

// SockaddrTIPC implements the Sockaddr interface for AF_TIPC type sockets.
// For more information on TIPC, see: http://tipc.sourceforge.net/.
type SockaddrTIPC struct {
	// Scope is the publication scopes when binding service/service range.
	// Should be set to TIPC_CLUSTER_SCOPE or TIPC_NODE_SCOPE.
	Scope int

	// Addr is the type of address used to manipulate a socket. Addr must be
	// one of:
	//  - *TIPCSocketAddr: "id" variant in the C addr union
	//  - *TIPCServiceRange: "nameseq" variant in the C addr union
	//  - *TIPCServiceName: "name" variant in the C addr union
	//
	// If nil, EINVAL will be returned when the structure is used.
	Addr TIPCAddr

	raw RawSockaddrTIPC
}

// TIPCAddr is implemented by types that can be used as an address for
// SockaddrTIPC. It is only implemented by *TIPCSocketAddr, *TIPCServiceRange,
// and *TIPCServiceName.
type TIPCAddr interface {
	tipcAddrtype() uint8
	tipcAddr() [12]byte
}

func (sa *TIPCSocketAddr) tipcAddr() [12]byte {
	var out [12]byte
	copy(out[:], (*(*[unsafe.Sizeof(TIPCSocketAddr{})]byte)(unsafe.Pointer(sa)))[:])
	return out
}

func (sa *TIPCSocketAddr) tipcAddrtype() uint8 { return TIPC_SOCKET_ADDR }

func (sa *TIPCServiceRange) tipcAddr() [12]byte {
	var out [12]byte
	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceRange{})]byte)(unsafe.Pointer(sa)))[:])
	return out
}

func (sa *TIPCServiceRange) tipcAddrtype() uint8 { return TIPC_SERVICE_RANGE }

func (sa *TIPCServiceName) tipcAddr() [12]byte {
	var out [12]byte
	copy(out[:], (*(*[unsafe.Sizeof(TIPCServiceName{})]byte)(unsafe.Pointer(sa)))[:])
	return out
}

func (sa *TIPCServiceName) tipcAddrtype() uint8 { return TIPC_SERVICE_ADDR }

func (sa *SockaddrTIPC) sockaddr() (unsafe.Pointer, _Socklen, error) {
	if sa.Addr == nil {
		return nil, 0, EINVAL
	}
	sa.raw.Family = AF_TIPC
	sa.raw.Scope = int8(sa.Scope)
	sa.raw.Addrtype = sa.Addr.tipcAddrtype()
	sa.raw.Addr = sa.Addr.tipcAddr()
	return unsafe.Pointer(&sa.raw), SizeofSockaddrTIPC, nil
}

// SockaddrL2TPIP implements the Sockaddr interface for IPPROTO_L2TP/AF_INET sockets.
type SockaddrL2TPIP struct {
	Addr   [4]byte
	ConnId uint32
	raw    RawSockaddrL2TPIP
}

func (sa *SockaddrL2TPIP) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_INET
	sa.raw.Conn_id = sa.ConnId
	sa.raw.Addr = sa.Addr
	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP, nil
}

// SockaddrL2TPIP6 implements the Sockaddr interface for IPPROTO_L2TP/AF_INET6 sockets.
type SockaddrL2TPIP6 struct {
	Addr   [16]byte
	ZoneId uint32
	ConnId uint32
	raw    RawSockaddrL2TPIP6
}

func (sa *SockaddrL2TPIP6) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_INET6
	sa.raw.Conn_id = sa.ConnId
	sa.raw.Scope_id = sa.ZoneId
	sa.raw.Addr = sa.Addr
	return unsafe.Pointer(&sa.raw), SizeofSockaddrL2TPIP6, nil
}

// SockaddrIUCV implements the Sockaddr interface for AF_IUCV sockets.
type SockaddrIUCV struct {
	UserID string
	Name   string
	raw    RawSockaddrIUCV
}

func (sa *SockaddrIUCV) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Family = AF_IUCV
	// These are EBCDIC encoded by the kernel, but we still need to pad them
	// with blanks. Initializing with blanks allows the caller to feed in either
	// a padded or an unpadded string.
	for i := 0; i < 8; i++ {
		sa.raw.Nodeid[i] = ' '
		sa.raw.User_id[i] = ' '
		sa.raw.Name[i] = ' '
	}
	if len(sa.UserID) > 8 || len(sa.Name) > 8 {
		return nil, 0, EINVAL
	}
	for i, b := range []byte(sa.UserID[:]) {
		sa.raw.User_id[i] = int8(b)
	}
	for i, b := range []byte(sa.Name[:]) {
		sa.raw.Name[i] = int8(b)
	}
	return unsafe.Pointer(&sa.raw), SizeofSockaddrIUCV, nil
}

type SockaddrNFC struct {
	DeviceIdx   uint32
	TargetIdx   uint32
	NFCProtocol uint32
	raw         RawSockaddrNFC
}

func (sa *SockaddrNFC) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Sa_family = AF_NFC
	sa.raw.Dev_idx = sa.DeviceIdx
	sa.raw.Target_idx = sa.TargetIdx
	sa.raw.Nfc_protocol = sa.NFCProtocol
	return unsafe.Pointer(&sa.raw), SizeofSockaddrNFC, nil
}

type SockaddrNFCLLCP struct {
	DeviceIdx      uint32
	TargetIdx      uint32
	NFCProtocol    uint32
	DestinationSAP uint8
	SourceSAP      uint8
	ServiceName    string
	raw            RawSockaddrNFCLLCP
}

func (sa *SockaddrNFCLLCP) sockaddr() (unsafe.Pointer, _Socklen, error) {
	sa.raw.Sa_family = AF_NFC
	sa.raw.Dev_idx = sa.DeviceIdx
	sa.raw.Target_idx = sa.TargetIdx
	sa.raw.Nfc_protocol = sa.NFCProtocol
	sa.raw.Dsap = sa.DestinationSAP
	sa.raw.Ssap = sa.SourceSAP
	if len(sa.ServiceName) > len(sa.raw.Service_name) {
		return nil, 0, EINVAL
	}
	copy(sa.raw.Service_name[:], sa.ServiceName)
	sa.raw.SetServiceNameLen(len(sa.ServiceName))
	return unsafe.Pointer(&sa.raw), SizeofSockaddrNFCLLCP, nil
}

var socketProtocol = func(fd int) (int, error) {
	return GetsockoptInt(fd, SOL_SOCKET, SO_PROTOCOL)
}

func anyToSockaddr(fd int, rsa *RawSockaddrAny) (Sockaddr, error) {
	switch rsa.Addr.Family {
	case AF_NETLINK:
		pp := (*RawSockaddrNetlink)(unsafe.Pointer(rsa))
		sa := new(SockaddrNetlink)
		sa.Family = pp.Family
		sa.Pad = pp.Pad
		sa.Pid = pp.Pid
		sa.Groups = pp.Groups
		return sa, nil

	case AF_PACKET:
		pp := (*RawSockaddrLinklayer)(unsafe.Pointer(rsa))
		sa := new(SockaddrLinklayer)
		sa.Protocol = pp.Protocol
		sa.Ifindex = int(pp.Ifindex)
		sa.Hatype = pp.Hatype
		sa.Pkttype = pp.Pkttype
		sa.Halen = pp.Halen
		sa.Addr = pp.Addr
		return sa, nil

	case AF_UNIX:
		pp := (*RawSockaddrUnix)(unsafe.Pointer(rsa))
		sa := new(SockaddrUnix)
		if pp.Path[0] == 0 {
			// "Abstract" Unix domain socket.
			// Rewrite leading NUL as @ for textual display.
			// (This is the standard convention.)
			// Not friendly to overwrite in place,
			// but the callers below don't care.
			pp.Path[0] = '@'
		}

		// Assume path ends at NUL.
		// This is not technically the Linux semantics for
		// abstract Unix domain sockets--they are supposed
		// to be uninterpreted fixed-size binary blobs--but
		// everyone uses this convention.
		n := 0
		for n < len(pp.Path) && pp.Path[n] != 0 {
			n++
		}
		sa.Name = string(unsafe.Slice((*byte)(unsafe.Pointer(&pp.Path[0])), n))
		return sa, nil

	case AF_INET:
		proto, err := socketProtocol(fd)
		if err != nil {
			return nil, err
		}

		switch proto {
		case IPPROTO_L2TP:
			pp := (*RawSockaddrL2TPIP)(unsafe.Pointer(rsa))
			sa := new(SockaddrL2TPIP)
			sa.ConnId = pp.Conn_id
			sa.Addr = pp.Addr
			return sa, nil
		default:
			pp := (*RawSockaddrInet4)(unsafe.Pointer(rsa))
			sa := new(SockaddrInet4)
			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
			sa.Port = int(p[0])<<8 + int(p[1])
			sa.Addr = pp.Addr
			return sa, nil
		}

	case AF_INET6:
		proto, err := socketProtocol(fd)
		if err != nil {
			return nil, err
		}

		switch proto {
		case IPPROTO_L2TP:
			pp := (*RawSockaddrL2TPIP6)(unsafe.Pointer(rsa))
			sa := new(SockaddrL2TPIP6)
			sa.ConnId = pp.Conn_id
			sa.ZoneId = pp.Scope_id
			sa.Addr = pp.Addr
			return sa, nil
		default:
			pp := (*RawSockaddrInet6)(unsafe.Pointer(rsa))
			sa := new(SockaddrInet6)
			p := (*[2]byte)(unsafe.Pointer(&pp.Port))
			sa.Port = int(p[0])<<8 + int(p[1])
			sa.ZoneId = pp.Scope_id
			sa.Addr = pp.Addr
			return sa, nil
		}

	case AF_VSOCK:
		pp := (*RawSockaddrVM)(unsafe.Pointer(rsa))
		sa := &SockaddrVM{
			CID:   pp.Cid,
			Port:  pp.Port,
			Flags: pp.Flags,
		}
		return sa, nil
	case AF_BLUETOOTH:
		proto, err := socketProtocol(fd)
		if err != nil {
			return nil, err
		}
		// only BTPROTO_L2CAP and BTPROTO_RFCOMM can accept connections
		switch proto {
		case BTPROTO_L2CAP:
			pp := (*RawSockaddrL2)(unsafe.Pointer(rsa))
			sa := &SockaddrL2{
				PSM:      pp.Psm,
				CID:      pp.Cid,
				Addr:     pp.Bdaddr,
				AddrType: pp.Bdaddr_type,
			}
			return sa, nil
		case BTPROTO_RFCOMM:
			pp := (*RawSockaddrRFCOMM)(unsafe.Pointer(rsa))
			sa := &SockaddrRFCOMM{
				Channel: pp.Channel,
				Addr:    pp.Bdaddr,
			}
			return sa, nil
		}
	case AF_XDP:
		pp := (*RawSockaddrXDP)(unsafe.Pointer(rsa))
		sa := &SockaddrXDP{
			Flags:        pp.Flags,
			Ifindex:      pp.Ifindex,
			QueueID:      pp.Queue_id,
			SharedUmemFD: pp.Shared_umem_fd,
		}
		return sa, nil
	case AF_PPPOX:
		pp := (*RawSockaddrPPPoX)(unsafe.Pointer(rsa))
		if binary.BigEndian.Uint32(pp[2:6]) != px_proto_oe {
			return nil, EINVAL
		}
		sa := &SockaddrPPPoE{
			SID:    binary.BigEndian.Uint16(pp[6:8]),
			Remote: pp[8:14],
		}
		for i := 14; i < 14+IFNAMSIZ; i++ {
			if pp[i] == 0 {
				sa.Dev = string(pp[14:i])
				break
			}
		}
		return sa, nil
	case AF_TIPC:
		pp := (*RawSockaddrTIPC)(unsafe.Pointer(rsa))

		sa := &SockaddrTIPC{
			Scope: int(pp.Scope),
		}

		// Determine which union variant is present in pp.Addr by checking
		// pp.Addrtype.
		switch pp.Addrtype {
		case TIPC_SERVICE_RANGE:
			sa.Addr = (*TIPCServiceRange)(unsafe.Pointer(&pp.Addr))
		case TIPC_SERVICE_ADDR:
			sa.Addr = (*TIPCServiceName)(unsafe.Pointer(&pp.Addr))
		case TIPC_SOCKET_ADDR:
			sa.Addr = (*TIPCSocketAddr)(unsafe.Pointer(&pp.Addr))
		default:
			return nil, EINVAL
		}

		return sa, nil
	case AF_IUCV:
		pp := (*RawSockaddrIUCV)(unsafe.Pointer(rsa))

		var user [8]byte
		var name [8]byte

		for i := 0; i < 8; i++ {
			user[i] = byte(pp.User_id[i])
			name[i] = byte(pp.Name[i])
		}

		sa := &SockaddrIUCV{
			UserID: string(user[:]),
			Name:   string(name[:]),
		}
		return sa, nil

	case AF_CAN:
		proto, err := socketProtocol(fd)
		if err != nil {
			return nil, err
		}

		pp := (*RawSockaddrCAN)(unsafe.Pointer(rsa))

		switch proto {
		case CAN_J1939:
			sa := &SockaddrCANJ1939{
				Ifindex: int(pp.Ifindex),
			}
			name := (*[8]byte)(unsafe.Pointer(&sa.Name))
			for i := 0; i < 8; i++ {
				name[i] = pp.Addr[i]
			}
			pgn := (*[4]byte)(unsafe.Pointer(&sa.PGN))
			for i := 0; i < 4; i++ {
				pgn[i] = pp.Addr[i+8]
			}
			addr := (*[1]byte)(unsafe.Pointer(&sa.Addr))
			addr[0] = pp.Addr[12]
			return sa, nil
		default:
			sa := &SockaddrCAN{
				Ifindex: int(pp.Ifindex),
			}
			rx := (*[4]byte)(unsafe.Pointer(&sa.RxID))
			for i := 0; i < 4; i++ {
				rx[i] = pp.Addr[i]
			}
			tx := (*[4]byte)(unsafe.Pointer(&sa.TxID))
			for i := 0; i < 4; i++ {
				tx[i] = pp.Addr[i+4]
			}
			return sa, nil
		}
	case AF_NFC:
		proto, err := socketProtocol(fd)
		if err != nil {
			return nil, err
		}
		switch proto {
		case NFC_SOCKPROTO_RAW:
			pp := (*RawSockaddrNFC)(unsafe.Pointer(rsa))
			sa := &SockaddrNFC{
				DeviceIdx:   pp.Dev_idx,
				TargetIdx:   pp.Target_idx,
				NFCProtocol: pp.Nfc_protocol,
			}
			return sa, nil
		case NFC_SOCKPROTO_LLCP:
			pp := (*RawSockaddrNFCLLCP)(unsafe.Pointer(rsa))
			if uint64(pp.Service_name_len) > uint64(len(pp.Service_name)) {
				return nil, EINVAL
			}
			sa := &SockaddrNFCLLCP{
				DeviceIdx:      pp.Dev_idx,
				TargetIdx:      pp.Target_idx,
				NFCProtocol:    pp.Nfc_protocol,
				DestinationSAP: pp.Dsap,
				SourceSAP:      pp.Ssap,
				ServiceName:    string(pp.Service_name[:pp.Service_name_len]),
			}
			return sa, nil
		default:
			return nil, EINVAL
		}
	}
	return nil, EAFNOSUPPORT
}

func Accept(fd int) (nfd int, sa Sockaddr, err error) {
	var rsa RawSockaddrAny
	var len _Socklen = SizeofSockaddrAny
	nfd, err = accept4(fd, &rsa, &len, 0)
	if err != nil {
		return
	}
	sa, err = anyToSockaddr(fd, &rsa)
	if err != nil {
		Close(nfd)
		nfd = 0
	}
	return
}

func Accept4(fd int, flags int) (nfd int, sa Sockaddr, err error) {
	var rsa RawSockaddrAny
	var len _Socklen = SizeofSockaddrAny
	nfd, err = accept4(fd, &rsa, &len, flags)
	if err != nil {
		return
	}
	if len > SizeofSockaddrAny {
		panic("RawSockaddrAny too small")
	}
	sa, err = anyToSockaddr(fd, &rsa)
	if err != nil {
		Close(nfd)
		nfd = 0
	}
	return
}

func Getsockname(fd int) (sa Sockaddr, err error) {
	var rsa RawSockaddrAny
	var len _Socklen = SizeofSockaddrAny
	if err = getsockname(fd, &rsa, &len); err != nil {
		return
	}
	return anyToSockaddr(fd, &rsa)
}

func GetsockoptIPMreqn(fd, level, opt int) (*IPMreqn, error) {
	var value IPMreqn
	vallen := _Socklen(SizeofIPMreqn)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
}

func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
	var value Ucred
	vallen := _Socklen(SizeofUcred)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
}

func GetsockoptTCPInfo(fd, level, opt int) (*TCPInfo, error) {
	var value TCPInfo
	vallen := _Socklen(SizeofTCPInfo)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
}

// GetsockoptString returns the string value of the socket option opt for the
// socket associated with fd at the given socket level.
func GetsockoptString(fd, level, opt int) (string, error) {
	buf := make([]byte, 256)
	vallen := _Socklen(len(buf))
	err := getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
	if err != nil {
		if err == ERANGE {
			buf = make([]byte, vallen)
			err = getsockopt(fd, level, opt, unsafe.Pointer(&buf[0]), &vallen)
		}
		if err != nil {
			return "", err
		}
	}
	return ByteSliceToString(buf[:vallen]), nil
}

func GetsockoptTpacketStats(fd, level, opt int) (*TpacketStats, error) {
	var value TpacketStats
	vallen := _Socklen(SizeofTpacketStats)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
}

func GetsockoptTpacketStatsV3(fd, level, opt int) (*TpacketStatsV3, error) {
	var value TpacketStatsV3
	vallen := _Socklen(SizeofTpacketStatsV3)
	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
	return &value, err
}

func SetsockoptIPMreqn(fd, level, opt int, mreq *IPMreqn) (err error) {
	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
}

func SetsockoptPacketMreq(fd, level, opt int, mreq *PacketMreq) error {
	return setsockopt(fd, level, opt, unsafe.Pointer(mreq), unsafe.Sizeof(*mreq))
}

// SetsockoptSockFprog attaches a classic BPF or an extended BPF program to a
// socket to filter incoming packets.  See 'man 7 socket' for usage information.
func SetsockoptSockFprog(fd, level, opt int, fprog *SockFprog) error {
	return setsockopt(fd, level, opt, unsafe.Pointer(fprog), unsafe.Sizeof(*fprog))
}

func SetsockoptCanRawFilter(fd, level, opt int, filter []CanFilter) error {
	var p unsafe.Pointer
	if len(filter) > 0 {
		p = unsafe.Pointer(&filter[0])
	}
	return setsockopt(fd, level, opt, p, uintptr(len(filter)*SizeofCanFilter))
}

func SetsockoptTpacketReq(fd, level, opt int, tp *TpacketReq) error {
	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
}

func SetsockoptTpacketReq3(fd, level, opt int, tp *TpacketReq3) error {
	return setsockopt(fd, level, opt, unsafe.Pointer(tp), unsafe.Sizeof(*tp))
}

func SetsockoptTCPRepairOpt(fd, level, opt int, o []TCPRepairOpt) (err error) {
	if len(o) == 0 {
		return EINVAL
	}
	return setsockopt(fd, level, opt, unsafe.Pointer(&o[0]), uintptr(SizeofTCPRepairOpt*len(o)))
}

func SetsockoptTCPMD5Sig(fd, level, opt int, s *TCPMD5Sig) error {
	return setsockopt(fd, level, opt, unsafe.Pointer(s), unsafe.Sizeof(*s))
}

// Keyctl Commands (http://man7.org/linux/man-pages/man2/keyctl.2.html)

// KeyctlInt calls keyctl commands in which each argument is an int.
// These commands are KEYCTL_REVOKE, KEYCTL_CHOWN, KEYCTL_CLEAR, KEYCTL_LINK,
// KEYCTL_UNLINK, KEYCTL_NEGATE, KEYCTL_SET_REQKEY_KEYRING, KEYCTL_SET_TIMEOUT,
// KEYCTL_ASSUME_AUTHORITY, KEYCTL_SESSION_TO_PARENT, KEYCTL_REJECT,
// KEYCTL_INVALIDATE, and KEYCTL_GET_PERSISTENT.
//sys	KeyctlInt(cmd int, arg2 int, arg3 int, arg4 int, arg5 int) (ret int, err error) = SYS_KEYCTL

// KeyctlBuffer calls keyctl commands in which the third and fourth
// arguments are a buffer and its length, respectively.
// These commands are KEYCTL_UPDATE, KEYCTL_READ, and KEYCTL_INSTANTIATE.
//sys	KeyctlBuffer(cmd int, arg2 int, buf []byte, arg5 int) (ret int, err error) = SYS_KEYCTL

// KeyctlString calls keyctl commands which return a string.
// These commands are KEYCTL_DESCRIBE and KEYCTL_GET_SECURITY.
func KeyctlString(cmd int, id int) (string, error) {
	// We must loop as the string data may change in between the syscalls.
	// We could allocate a large buffer here to reduce the chance that the
	// syscall needs to be called twice; however, this is unnecessary as
	// the performance loss is negligible.
	var buffer []byte
	for {
		// Try to fill the buffer with data
		length, err := KeyctlBuffer(cmd, id, buffer, 0)
		if err != nil {
			return "", err
		}

		// Check if the data was written
		if length <= len(buffer) {
			// Exclude the null terminator
			return string(buffer[:length-1]), nil
		}

		// Make a bigger buffer if needed
		buffer = make([]byte, length)
	}
}

// Keyctl commands with special signatures.

// KeyctlGetKeyringID implements the KEYCTL_GET_KEYRING_ID command.
// See the full documentation at:
// http://man7.org/linux/man-pages/man3/keyctl_get_keyring_ID.3.html
func KeyctlGetKeyringID(id int, create bool) (ringid int, err error) {
	createInt := 0
	if create {
		createInt = 1
	}
	return KeyctlInt(KEYCTL_GET_KEYRING_ID, id, createInt, 0, 0)
}

// KeyctlSetperm implements the KEYCTL_SETPERM command. The perm value is the
// key handle permission mask as described in the "keyctl setperm" section of
// http://man7.org/linux/man-pages/man1/keyctl.1.html.
// See the full documentation at:
// http://man7.org/linux/man-pages/man3/keyctl_setperm.3.html
func KeyctlSetperm(id int, perm uint32) error {
	_, err := KeyctlInt(KEYCTL_SETPERM, id, int(perm), 0, 0)
	return err
}

//sys	keyctlJoin(cmd int, arg2 string) (ret int, err error) = SYS_KEYCTL

// KeyctlJoinSessionKeyring implements the KEYCTL_JOIN_SESSION_KEYRING command.
// See the full documentation at:
// http://man7.org/linux/man-pages/man3/keyctl_join_session_keyring.3.html
func KeyctlJoinSessionKeyring(name string) (ringid int, err error) {
	return keyctlJoin(KEYCTL_JOIN_SESSION_KEYRING, name)
}

//sys	keyctlSearch(cmd int, arg2 int, arg3 string, arg4 string, arg5 int) (ret int, err error) = SYS_KEYCTL

// KeyctlSearch implements the KEYCTL_SEARCH command.
// See the full documentation at:
// http://man7.org/linux/man-pages/man3/keyctl_search.3.html
func KeyctlSearch(ringid int, keyType, description string, destRingid int) (id int, err error) {
	return keyctlSearch(KEYCTL_SEARCH, ringid, keyType, description, destRingid)
}

//sys	keyctlIOV(cmd int, arg2 int, payload []Iovec, arg5 int) (err error) = SYS_KEYCTL

// KeyctlInstantiateIOV implements the KEYCTL_INSTANTIATE_IOV command. This
// command is similar to KEYCTL_INSTANTIATE, except that the payload is a slice
// of Iovec (each of which represents a buffer) instead of a single buffer.
// See the full documentation at:
// http://man7.org/linux/man-pages/man3/keyctl_instantiate_iov.3.html
func KeyctlInstantiateIOV(id int, payload []Iovec, ringid int) error {
	return keyctlIOV(KEYCTL_INSTANTIATE_IOV, id, payload, ringid)
}

//sys	keyctlDH(cmd int, arg2 *KeyctlDHParams, buf []byte) (ret int, err error) = SYS_KEYCTL

// KeyctlDHCompute implements the KEYCTL_DH_COMPUTE command. This command
// computes a Diffie-Hellman shared secret based on the provide params. The
// secret is written to the provided buffer and the returned size is the number
// of bytes written (returning an error if there is insufficient space in the
// buffer). If a nil buffer is passed in, this function returns the minimum
// buffer length needed to store the appropriate data. Note that this differs
// from KEYCTL_READ's behavior which always returns the requested payload size.
// See the full documentation at:
// http://man7.org/linux/man-pages/man3/keyctl_dh_compute.3.html
func KeyctlDHCompute(params *KeyctlDHParams, buffer []byte) (size int, err error) {
	return keyctlDH(KEYCTL_DH_COMPUTE, params, buffer)
}

// KeyctlRestrictKeyring implements the KEYCTL_RESTRICT_KEYRING command. This
// command limits the set of keys that can be linked to the keyring, regardless
// of keyring permissions. The command requires the "setattr" permission.
//
// When called with an empty keyType the command locks the keyring, preventing
// any further keys from being linked to the keyring.
//
// The "asymmetric" keyType defines restrictions requiring key payloads to be
// DER encoded X.509 certificates signed by keys in another keyring. Restrictions
// for "asymmetric" include "builtin_trusted", "builtin_and_secondary_trusted",
// "key_or_keyring:<key>", and "key_or_keyring:<key>:chain".
//
// As of Linux 4.12, only the "asymmetric" keyType defines type-specific
// restrictions.
//
// See the full documentation at:
// http://man7.org/linux/man-pages/man3/keyctl_restrict_keyring.3.html
// http://man7.org/linux/man-pages/man2/keyctl.2.html
func KeyctlRestrictKeyring(ringid int, keyType string, restriction string) error {
	if keyType == "" {
		return keyctlRestrictKeyring(KEYCTL_RESTRICT_KEYRING, ringid)
	}
	return keyctlRestrictKeyringByType(KEYCTL_RESTRICT_KEYRING, ringid, keyType, restriction)
}

//sys	keyctlRestrictKeyringByType(cmd int, arg2 int, keyType string, restriction string) (err error) = SYS_KEYCTL
//sys	keyctlRestrictKeyring(cmd int, arg2 int) (err error) = SYS_KEYCTL

func recvmsgRaw(fd int, iov []Iovec, oob []byte, flags int, rsa *RawSockaddrAny) (n, oobn int, recvflags int, err error) {
	var msg Msghdr
	msg.Name = (*byte)(unsafe.Pointer(rsa))
	msg.Namelen = uint32(SizeofSockaddrAny)
	var dummy byte
	if len(oob) > 0 {
		if emptyIovecs(iov) {
			var sockType int
			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
			if err != nil {
				return
			}
			// receive at least one normal byte
			if sockType != SOCK_DGRAM {
				var iova [1]Iovec
				iova[0].Base = &dummy
				iova[0].SetLen(1)
				iov = iova[:]
			}
		}
		msg.Control = &oob[0]
		msg.SetControllen(len(oob))
	}
	if len(iov) > 0 {
		msg.Iov = &iov[0]
		msg.SetIovlen(len(iov))
	}
	if n, err = recvmsg(fd, &msg, flags); err != nil {
		return
	}
	oobn = int(msg.Controllen)
	recvflags = int(msg.Flags)
	return
}

func sendmsgN(fd int, iov []Iovec, oob []byte, ptr unsafe.Pointer, salen _Socklen, flags int) (n int, err error) {
	var msg Msghdr
	msg.Name = (*byte)(ptr)
	msg.Namelen = uint32(salen)
	var dummy byte
	var empty bool
	if len(oob) > 0 {
		empty = emptyIovecs(iov)
		if empty {
			var sockType int
			sockType, err = GetsockoptInt(fd, SOL_SOCKET, SO_TYPE)
			if err != nil {
				return 0, err
			}
			// send at least one normal byte
			if sockType != SOCK_DGRAM {
				var iova [1]Iovec
				iova[0].Base = &dummy
				iova[0].SetLen(1)
				iov = iova[:]
			}
		}
		msg.Control = &oob[0]
		msg.SetControllen(len(oob))
	}
	if len(iov) > 0 {
		msg.Iov = &iov[0]
		msg.SetIovlen(len(iov))
	}
	if n, err = sendmsg(fd, &msg, flags); err != nil {
		return 0, err
	}
	if len(oob) > 0 && empty {
		n = 0
	}
	return n, nil
}

// BindToDevice binds the socket associated with fd to device.
func BindToDevice(fd int, device string) (err error) {
	return SetsockoptString(fd, SOL_SOCKET, SO_BINDTODEVICE, device)
}

//sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
//sys	ptracePtr(request int, pid int, addr uintptr, data unsafe.Pointer) (err error) = SYS_PTRACE

func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err error) {
	// The peek requests are machine-size oriented, so we wrap it
	// to retrieve arbitrary-length data.

	// The ptrace syscall differs from glibc's ptrace.
	// Peeks returns the word in *data, not as the return value.

	var buf [SizeofPtr]byte

	// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
	// access (PEEKUSER warns that it might), but if we don't
	// align our reads, we might straddle an unmapped page
	// boundary and not get the bytes leading up to the page
	// boundary.
	n := 0
	if addr%SizeofPtr != 0 {
		err = ptracePtr(req, pid, addr-addr%SizeofPtr, unsafe.Pointer(&buf[0]))
		if err != nil {
			return 0, err
		}
		n += copy(out, buf[addr%SizeofPtr:])
		out = out[n:]
	}

	// Remainder.
	for len(out) > 0 {
		// We use an internal buffer to guarantee alignment.
		// It's not documented if this is necessary, but we're paranoid.
		err = ptracePtr(req, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
		if err != nil {
			return n, err
		}
		copied := copy(out, buf[0:])
		n += copied
		out = out[copied:]
	}

	return n, nil
}

func PtracePeekText(pid int, addr uintptr, out []byte) (count int, err error) {
	return ptracePeek(PTRACE_PEEKTEXT, pid, addr, out)
}

func PtracePeekData(pid int, addr uintptr, out []byte) (count int, err error) {
	return ptracePeek(PTRACE_PEEKDATA, pid, addr, out)
}

func PtracePeekUser(pid int, addr uintptr, out []byte) (count int, err error) {
	return ptracePeek(PTRACE_PEEKUSR, pid, addr, out)
}

func ptracePoke(pokeReq int, peekReq int, pid int, addr uintptr, data []byte) (count int, err error) {
	// As for ptracePeek, we need to align our accesses to deal
	// with the possibility of straddling an invalid page.

	// Leading edge.
	n := 0
	if addr%SizeofPtr != 0 {
		var buf [SizeofPtr]byte
		err = ptracePtr(peekReq, pid, addr-addr%SizeofPtr, unsafe.Pointer(&buf[0]))
		if err != nil {
			return 0, err
		}
		n += copy(buf[addr%SizeofPtr:], data)
		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
		err = ptrace(pokeReq, pid, addr-addr%SizeofPtr, word)
		if err != nil {
			return 0, err
		}
		data = data[n:]
	}

	// Interior.
	for len(data) > SizeofPtr {
		word := *((*uintptr)(unsafe.Pointer(&data[0])))
		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
		if err != nil {
			return n, err
		}
		n += SizeofPtr
		data = data[SizeofPtr:]
	}

	// Trailing edge.
	if len(data) > 0 {
		var buf [SizeofPtr]byte
		err = ptracePtr(peekReq, pid, addr+uintptr(n), unsafe.Pointer(&buf[0]))
		if err != nil {
			return n, err
		}
		copy(buf[0:], data)
		word := *((*uintptr)(unsafe.Pointer(&buf[0])))
		err = ptrace(pokeReq, pid, addr+uintptr(n), word)
		if err != nil {
			return n, err
		}
		n += len(data)
	}

	return n, nil
}

func PtracePokeText(pid int, addr uintptr, data []byte) (count int, err error) {
	return ptracePoke(PTRACE_POKETEXT, PTRACE_PEEKTEXT, pid, addr, data)
}

func PtracePokeData(pid int, addr uintptr, data []byte) (count int, err error) {
	return ptracePoke(PTRACE_POKEDATA, PTRACE_PEEKDATA, pid, addr, data)
}

func PtracePokeUser(pid int, addr uintptr, data []byte) (count int, err error) {
	return ptracePoke(PTRACE_POKEUSR, PTRACE_PEEKUSR, pid, addr, data)
}

// elfNT_PRSTATUS is a copy of the debug/elf.NT_PRSTATUS constant so
// x/sys/unix doesn't need to depend on debug/elf and thus
// compress/zlib, debug/dwarf, and other packages.
const elfNT_PRSTATUS = 1

func PtraceGetRegs(pid int, regsout *PtraceRegs) (err error) {
	var iov Iovec
	iov.Base = (*byte)(unsafe.Pointer(regsout))
	iov.SetLen(int(unsafe.Sizeof(*regsout)))
	return ptracePtr(PTRACE_GETREGSET, pid, uintptr(elfNT_PRSTATUS), unsafe.Pointer(&iov))
}

func PtraceSetRegs(pid int, regs *PtraceRegs) (err error) {
	var iov Iovec
	iov.Base = (*byte)(unsafe.Pointer(regs))
	iov.SetLen(int(unsafe.Sizeof(*regs)))
	return ptracePtr(PTRACE_SETREGSET, pid, uintptr(elfNT_PRSTATUS), unsafe.Pointer(&iov))
}

func PtraceSetOptions(pid int, options int) (err error) {
	return ptrace(PTRACE_SETOPTIONS, pid, 0, uintptr(options))
}

func PtraceGetEventMsg(pid int) (msg uint, err error) {
	var data _C_long
	err = ptracePtr(PTRACE_GETEVENTMSG, pid, 0, unsafe.Pointer(&data))
	msg = uint(data)
	return
}

func PtraceCont(pid int, signal int) (err error) {
	return ptrace(PTRACE_CONT, pid, 0, uintptr(signal))
}

func PtraceSyscall(pid int, signal int) (err error) {
	return ptrace(PTRACE_SYSCALL, pid, 0, uintptr(signal))
}

func PtraceSingleStep(pid int) (err error) { return ptrace(PTRACE_SINGLESTEP, pid, 0, 0) }

func PtraceInterrupt(pid int) (err error) { return ptrace(PTRACE_INTERRUPT, pid, 0, 0) }

func PtraceAttach(pid int) (err error) { return ptrace(PTRACE_ATTACH, pid, 0, 0) }

func PtraceSeize(pid int) (err error) { return ptrace(PTRACE_SEIZE, pid, 0, 0) }

func PtraceDetach(pid int) (err error) { return ptrace(PTRACE_DETACH, pid, 0, 0) }

//sys	reboot(magic1 uint, magic2 uint, cmd int, arg string) (err error)

func Reboot(cmd int) (err error) {
	return reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, cmd, "")
}

func direntIno(buf []byte) (uint64, bool) {
	return readInt(buf, unsafe.Offsetof(Dirent{}.Ino), unsafe.Sizeof(Dirent{}.Ino))
}

func direntReclen(buf []byte) (uint64, bool) {
	return readInt(buf, unsafe.Offsetof(Dirent{}.Reclen), unsafe.Sizeof(Dirent{}.Reclen))
}

func direntNamlen(buf []byte) (uint64, bool) {
	reclen, ok := direntReclen(buf)
	if !ok {
		return 0, false
	}
	return reclen - uint64(unsafe.Offsetof(Dirent{}.Name)), true
}

//sys	mount(source string, target string, fstype string, flags uintptr, data *byte) (err error)

func Mount(source string, target string, fstype string, flags uintptr, data string) (err error) {
	// Certain file systems get rather angry and EINVAL if you give
	// them an empty string of data, rather than NULL.
	if data == "" {
		return mount(source, target, fstype, flags, nil)
	}
	datap, err := BytePtrFromString(data)
	if err != nil {
		return err
	}
	return mount(source, target, fstype, flags, datap)
}

//sys	mountSetattr(dirfd int, pathname string, flags uint, attr *MountAttr, size uintptr) (err error) = SYS_MOUNT_SETATTR

// MountSetattr is a wrapper for mount_setattr(2).
// https://man7.org/linux/man-pages/man2/mount_setattr.2.html
//
// Requires kernel >= 5.12.
func MountSetattr(dirfd int, pathname string, flags uint, attr *MountAttr) error {
	return mountSetattr(dirfd, pathname, flags, attr, unsafe.Sizeof(*attr))
}

func Sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
	if raceenabled {
		raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	return sendfile(outfd, infd, offset, count)
}

// Sendto
// Recvfrom
// Socketpair

/*
 * Direct access
 */
//sys	Acct(path string) (err error)
//sys	AddKey(keyType string, description string, payload []byte, ringid int) (id int, err error)
//sys	Adjtimex(buf *Timex) (state int, err error)
//sysnb	Capget(hdr *CapUserHeader, data *CapUserData) (err error)
//sysnb	Capset(hdr *CapUserHeader, data *CapUserData) (err error)
//sys	Chdir(path string) (err error)
//sys	Chroot(path string) (err error)
//sys	ClockAdjtime(clockid int32, buf *Timex) (state int, err error)
//sys	ClockGetres(clockid int32, res *Timespec) (err error)
//sys	ClockGettime(clockid int32, time *Timespec) (err error)
//sys	ClockNanosleep(clockid int32, flags int, request *Timespec, remain *Timespec) (err error)
//sys	Close(fd int) (err error)
//sys	CloseRange(first uint, last uint, flags uint) (err error)
//sys	CopyFileRange(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int, err error)
//sys	DeleteModule(name string, flags int) (err error)
//sys	Dup(oldfd int) (fd int, err error)

func Dup2(oldfd, newfd int) error {
	return Dup3(oldfd, newfd, 0)
}

//sys	Dup3(oldfd int, newfd int, flags int) (err error)
//sysnb	EpollCreate1(flag int) (fd int, err error)
//sysnb	EpollCtl(epfd int, op int, fd int, event *EpollEvent) (err error)
//sys	Eventfd(initval uint, flags int) (fd int, err error) = SYS_EVENTFD2
//sys	Exit(code int) = SYS_EXIT_GROUP
//sys	Fallocate(fd int, mode uint32, off int64, len int64) (err error)
//sys	Fchdir(fd int) (err error)
//sys	Fchmod(fd int, mode uint32) (err error)
//sys	Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
//sys	Fdatasync(fd int) (err error)
//sys	Fgetxattr(fd int, attr string, dest []byte) (sz int, err error)
//sys	FinitModule(fd int, params string, flags int) (err error)
//sys	Flistxattr(fd int, dest []byte) (sz int, err error)
//sys	Flock(fd int, how int) (err error)
//sys	Fremovexattr(fd int, attr string) (err error)
//sys	Fsetxattr(fd int, attr string, dest []byte, flags int) (err error)
//sys	Fsync(fd int) (err error)
//sys	Fsmount(fd int, flags int, mountAttrs int) (fsfd int, err error)
//sys	Fsopen(fsName string, flags int) (fd int, err error)
//sys	Fspick(dirfd int, pathName string, flags int) (fd int, err error)

//sys	fsconfig(fd int, cmd uint, key *byte, value *byte, aux int) (err error)

func fsconfigCommon(fd int, cmd uint, key string, value *byte, aux int) (err error) {
	var keyp *byte
	if keyp, err = BytePtrFromString(key); err != nil {
		return
	}
	return fsconfig(fd, cmd, keyp, value, aux)
}

// FsconfigSetFlag is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_SET_FLAG.
//
// fd is the filesystem context to act upon.
// key the parameter key to set.
func FsconfigSetFlag(fd int, key string) (err error) {
	return fsconfigCommon(fd, FSCONFIG_SET_FLAG, key, nil, 0)
}

// FsconfigSetString is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_SET_STRING.
//
// fd is the filesystem context to act upon.
// key the parameter key to set.
// value is the parameter value to set.
func FsconfigSetString(fd int, key string, value string) (err error) {
	var valuep *byte
	if valuep, err = BytePtrFromString(value); err != nil {
		return
	}
	return fsconfigCommon(fd, FSCONFIG_SET_STRING, key, valuep, 0)
}

// FsconfigSetBinary is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_SET_BINARY.
//
// fd is the filesystem context to act upon.
// key the parameter key to set.
// value is the parameter value to set.
func FsconfigSetBinary(fd int, key string, value []byte) (err error) {
	if len(value) == 0 {
		return EINVAL
	}
	return fsconfigCommon(fd, FSCONFIG_SET_BINARY, key, &value[0], len(value))
}

// FsconfigSetPath is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_SET_PATH.
//
// fd is the filesystem context to act upon.
// key the parameter key to set.
// path is a non-empty path for specified key.
// atfd is a file descriptor at which to start lookup from or AT_FDCWD.
func FsconfigSetPath(fd int, key string, path string, atfd int) (err error) {
	var valuep *byte
	if valuep, err = BytePtrFromString(path); err != nil {
		return
	}
	return fsconfigCommon(fd, FSCONFIG_SET_PATH, key, valuep, atfd)
}

// FsconfigSetPathEmpty is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_SET_PATH_EMPTY. The same as
// FconfigSetPath but with AT_PATH_EMPTY implied.
func FsconfigSetPathEmpty(fd int, key string, path string, atfd int) (err error) {
	var valuep *byte
	if valuep, err = BytePtrFromString(path); err != nil {
		return
	}
	return fsconfigCommon(fd, FSCONFIG_SET_PATH_EMPTY, key, valuep, atfd)
}

// FsconfigSetFd is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_SET_FD.
//
// fd is the filesystem context to act upon.
// key the parameter key to set.
// value is a file descriptor to be assigned to specified key.
func FsconfigSetFd(fd int, key string, value int) (err error) {
	return fsconfigCommon(fd, FSCONFIG_SET_FD, key, nil, value)
}

// FsconfigCreate is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_CMD_CREATE.
//
// fd is the filesystem context to act upon.
func FsconfigCreate(fd int) (err error) {
	return fsconfig(fd, FSCONFIG_CMD_CREATE, nil, nil, 0)
}

// FsconfigReconfigure is equivalent to fsconfig(2) called
// with cmd == FSCONFIG_CMD_RECONFIGURE.
//
// fd is the filesystem context to act upon.
func FsconfigReconfigure(fd int) (err error) {
	return fsconfig(fd, FSCONFIG_CMD_RECONFIGURE, nil, nil, 0)
}

//sys	Getdents(fd int, buf []byte) (n int, err error) = SYS_GETDENTS64
//sysnb	Getpgid(pid int) (pgid int, err error)

func Getpgrp() (pid int) {
	pid, _ = Getpgid(0)
	return
}

//sysnb	Getpid() (pid int)
//sysnb	Getppid() (ppid int)
//sys	Getpriority(which int, who int) (prio int, err error)
//sys	Getrandom(buf []byte, flags int) (n int, err error)
//sysnb	Getrusage(who int, rusage *Rusage) (err error)
//sysnb	Getsid(pid int) (sid int, err error)
//sysnb	Gettid() (tid int)
//sys	Getxattr(path string, attr string, dest []byte) (sz int, err error)
//sys	InitModule(moduleImage []byte, params string) (err error)
//sys	InotifyAddWatch(fd int, pathname string, mask uint32) (watchdesc int, err error)
//sysnb	InotifyInit1(flags int) (fd int, err error)
//sysnb	InotifyRmWatch(fd int, watchdesc uint32) (success int, err error)
//sysnb	Kill(pid int, sig syscall.Signal) (err error)
//sys	Klogctl(typ int, buf []byte) (n int, err error) = SYS_SYSLOG
//sys	Lgetxattr(path string, attr string, dest []byte) (sz int, err error)
//sys	Listxattr(path string, dest []byte) (sz int, err error)
//sys	Llistxattr(path string, dest []byte) (sz int, err error)
//sys	Lremovexattr(path string, attr string) (err error)
//sys	Lsetxattr(path string, attr string, data []byte, flags int) (err error)
//sys	MemfdCreate(name string, flags int) (fd int, err error)
//sys	Mkdirat(dirfd int, path string, mode uint32) (err error)
//sys	Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
//sys	MoveMount(fromDirfd int, fromPathName string, toDirfd int, toPathName string, flags int) (err error)
//sys	Nanosleep(time *Timespec, leftover *Timespec) (err error)
//sys	OpenTree(dfd int, fileName string, flags uint) (r int, err error)
//sys	PerfEventOpen(attr *PerfEventAttr, pid int, cpu int, groupFd int, flags int) (fd int, err error)
//sys	PivotRoot(newroot string, putold string) (err error) = SYS_PIVOT_ROOT
//sys	Prctl(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (err error)
//sys	pselect6(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *sigset_argpack) (n int, err error)
//sys	read(fd int, p []byte) (n int, err error)
//sys	Removexattr(path string, attr string) (err error)
//sys	Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error)
//sys	RequestKey(keyType string, description string, callback string, destRingid int) (id int, err error)
//sys	Setdomainname(p []byte) (err error)
//sys	Sethostname(p []byte) (err error)
//sysnb	Setpgid(pid int, pgid int) (err error)
//sysnb	Setsid() (pid int, err error)
//sysnb	Settimeofday(tv *Timeval) (err error)
//sys	Setns(fd int, nstype int) (err error)

//go:linkname syscall_prlimit syscall.prlimit
func syscall_prlimit(pid, resource int, newlimit, old *syscall.Rlimit) error

func Prlimit(pid, resource int, newlimit, old *Rlimit) error {
	// Just call the syscall version, because as of Go 1.21
	// it will affect starting a new process.
	return syscall_prlimit(pid, resource, (*syscall.Rlimit)(newlimit), (*syscall.Rlimit)(old))
}

// PrctlRetInt performs a prctl operation specified by option and further
// optional arguments arg2 through arg5 depending on option. It returns a
// non-negative integer that is returned by the prctl syscall.
func PrctlRetInt(option int, arg2 uintptr, arg3 uintptr, arg4 uintptr, arg5 uintptr) (int, error) {
	ret, _, err := Syscall6(SYS_PRCTL, uintptr(option), uintptr(arg2), uintptr(arg3), uintptr(arg4), uintptr(arg5), 0)
	if err != 0 {
		return 0, err
	}
	return int(ret), nil
}

func Setuid(uid int) (err error) {
	return syscall.Setuid(uid)
}

func Setgid(gid int) (err error) {
	return syscall.Setgid(gid)
}

func Setreuid(ruid, euid int) (err error) {
	return syscall.Setreuid(ruid, euid)
}

func Setregid(rgid, egid int) (err error) {
	return syscall.Setregid(rgid, egid)
}

func Setresuid(ruid, euid, suid int) (err error) {
	return syscall.Setresuid(ruid, euid, suid)
}

func Setresgid(rgid, egid, sgid int) (err error) {
	return syscall.Setresgid(rgid, egid, sgid)
}

// SetfsgidRetGid sets fsgid for current thread and returns previous fsgid set.
// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability.
// If the call fails due to other reasons, current fsgid will be returned.
func SetfsgidRetGid(gid int) (int, error) {
	return setfsgid(gid)
}

// SetfsuidRetUid sets fsuid for current thread and returns previous fsuid set.
// setfsgid(2) will return a non-nil error only if its caller lacks CAP_SETUID capability
// If the call fails due to other reasons, current fsuid will be returned.
func SetfsuidRetUid(uid int) (int, error) {
	return setfsuid(uid)
}

func Setfsgid(gid int) error {
	_, err := setfsgid(gid)
	return err
}

func Setfsuid(uid int) error {
	_, err := setfsuid(uid)
	return err
}

func Signalfd(fd int, sigmask *Sigset_t, flags int) (newfd int, err error) {
	return signalfd(fd, sigmask, _C__NSIG/8, flags)
}

//sys	Setpriority(which int, who int, prio int) (err error)
//sys	Setxattr(path string, attr string, data []byte, flags int) (err error)
//sys	signalfd(fd int, sigmask *Sigset_t, maskSize uintptr, flags int) (newfd int, err error) = SYS_SIGNALFD4
//sys	Statx(dirfd int, path string, flags int, mask int, stat *Statx_t) (err error)
//sys	Sync()
//sys	Syncfs(fd int) (err error)
//sysnb	Sysinfo(info *Sysinfo_t) (err error)
//sys	Tee(rfd int, wfd int, len int, flags int) (n int64, err error)
//sysnb	TimerfdCreate(clockid int, flags int) (fd int, err error)
//sysnb	TimerfdGettime(fd int, currValue *ItimerSpec) (err error)
//sysnb	TimerfdSettime(fd int, flags int, newValue *ItimerSpec, oldValue *ItimerSpec) (err error)
//sysnb	Tgkill(tgid int, tid int, sig syscall.Signal) (err error)
//sysnb	Times(tms *Tms) (ticks uintptr, err error)
//sysnb	Umask(mask int) (oldmask int)
//sysnb	Uname(buf *Utsname) (err error)
//sys	Unmount(target string, flags int) (err error) = SYS_UMOUNT2
//sys	Unshare(flags int) (err error)
//sys	write(fd int, p []byte) (n int, err error)
//sys	exitThread(code int) (err error) = SYS_EXIT
//sys	readv(fd int, iovs []Iovec) (n int, err error) = SYS_READV
//sys	writev(fd int, iovs []Iovec) (n int, err error) = SYS_WRITEV
//sys	preadv(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PREADV
//sys	pwritev(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr) (n int, err error) = SYS_PWRITEV
//sys	preadv2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PREADV2
//sys	pwritev2(fd int, iovs []Iovec, offs_l uintptr, offs_h uintptr, flags int) (n int, err error) = SYS_PWRITEV2

// minIovec is the size of the small initial allocation used by
// Readv, Writev, etc.
//
// This small allocation gets stack allocated, which lets the
// common use case of len(iovs) <= minIovs avoid more expensive
// heap allocations.
const minIovec = 8

// appendBytes converts bs to Iovecs and appends them to vecs.
func appendBytes(vecs []Iovec, bs [][]byte) []Iovec {
	for _, b := range bs {
		var v Iovec
		v.SetLen(len(b))
		if len(b) > 0 {
			v.Base = &b[0]
		} else {
			v.Base = (*byte)(unsafe.Pointer(&_zero))
		}
		vecs = append(vecs, v)
	}
	return vecs
}

// offs2lohi splits offs into its low and high order bits.
func offs2lohi(offs int64) (lo, hi uintptr) {
	const longBits = SizeofLong * 8
	return uintptr(offs), uintptr(uint64(offs) >> (longBits - 1) >> 1) // two shifts to avoid false positive in vet
}

func Readv(fd int, iovs [][]byte) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	n, err = readv(fd, iovecs)
	readvRacedetect(iovecs, n, err)
	return n, err
}

func Preadv(fd int, iovs [][]byte, offset int64) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	lo, hi := offs2lohi(offset)
	n, err = preadv(fd, iovecs, lo, hi)
	readvRacedetect(iovecs, n, err)
	return n, err
}

func Preadv2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	lo, hi := offs2lohi(offset)
	n, err = preadv2(fd, iovecs, lo, hi, flags)
	readvRacedetect(iovecs, n, err)
	return n, err
}

func readvRacedetect(iovecs []Iovec, n int, err error) {
	if !raceenabled {
		return
	}
	for i := 0; n > 0 && i < len(iovecs); i++ {
		m := int(iovecs[i].Len)
		if m > n {
			m = n
		}
		n -= m
		if m > 0 {
			raceWriteRange(unsafe.Pointer(iovecs[i].Base), m)
		}
	}
	if err == nil {
		raceAcquire(unsafe.Pointer(&ioSync))
	}
}

func Writev(fd int, iovs [][]byte) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	if raceenabled {
		raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	n, err = writev(fd, iovecs)
	writevRacedetect(iovecs, n)
	return n, err
}

func Pwritev(fd int, iovs [][]byte, offset int64) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	if raceenabled {
		raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	lo, hi := offs2lohi(offset)
	n, err = pwritev(fd, iovecs, lo, hi)
	writevRacedetect(iovecs, n)
	return n, err
}

func Pwritev2(fd int, iovs [][]byte, offset int64, flags int) (n int, err error) {
	iovecs := make([]Iovec, 0, minIovec)
	iovecs = appendBytes(iovecs, iovs)
	if raceenabled {
		raceReleaseMerge(unsafe.Pointer(&ioSync))
	}
	lo, hi := offs2lohi(offset)
	n, err = pwritev2(fd, iovecs, lo, hi, flags)
	writevRacedetect(iovecs, n)
	return n, err
}

func writevRacedetect(iovecs []Iovec, n int) {
	if !raceenabled {
		return
	}
	for i := 0; n > 0 && i < len(iovecs); i++ {
		m := int(iovecs[i].Len)
		if m > n {
			m = n
		}
		n -= m
		if m > 0 {
			raceReadRange(unsafe.Pointer(iovecs[i].Base), m)
		}
	}
}

// mmap varies by architecture; see syscall_linux_*.go.
//sys	munmap(addr uintptr, length uintptr) (err error)
//sys	mremap(oldaddr uintptr, oldlength uintptr, newlength uintptr, flags int, newaddr uintptr) (xaddr uintptr, err error)
//sys	Madvise(b []byte, advice int) (err error)
//sys	Mprotect(b []byte, prot int) (err error)
//sys	Mlock(b []byte) (err error)
//sys	Mlockall(flags int) (err error)
//sys	Msync(b []byte, flags int) (err error)
//sys	Munlock(b []byte) (err error)
//sys	Munlockall() (err error)

const (
	mremapFixed     = MREMAP_FIXED
	mremapDontunmap = MREMAP_DONTUNMAP
	mremapMaymove   = MREMAP_MAYMOVE
)

// Vmsplice splices user pages from a slice of Iovecs into a pipe specified by fd,
// using the specified flags.
func Vmsplice(fd int, iovs []Iovec, flags int) (int, error) {
	var p unsafe.Pointer
	if len(iovs) > 0 {
		p = unsafe.Pointer(&iovs[0])
	}

	n, _, errno := Syscall6(SYS_VMSPLICE, uintptr(fd), uintptr(p), uintptr(len(iovs)), uintptr(flags), 0, 0)
	if errno != 0 {
		return 0, syscall.Errno(errno)
	}

	return int(n), nil
}

func isGroupMember(gid int) bool {
	groups, err := Getgroups()
	if err != nil {
		return false
	}

	for _, g := range groups {
		if g == gid {
			return true
		}
	}
	return false
}

func isCapDacOverrideSet() bool {
	hdr := CapUserHeader{Version: LINUX_CAPABILITY_VERSION_3}
	data := [2]CapUserData{}
	err := Capget(&hdr, &data[0])

	return err == nil && data[0].Effective&(1<<CAP_DAC_OVERRIDE) != 0
}

//sys	faccessat(dirfd int, path string, mode uint32) (err error)
//sys	Faccessat2(dirfd int, path string, mode uint32, flags int) (err error)

func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
	if flags == 0 {
		return faccessat(dirfd, path, mode)
	}

	if err := Faccessat2(dirfd, path, mode, flags); err != ENOSYS && err != EPERM {
		return err
	}

	// The Linux kernel faccessat system call does not take any flags.
	// The glibc faccessat implements the flags itself; see
	// https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/faccessat.c;hb=HEAD
	// Because people naturally expect syscall.Faccessat to act
	// like C faccessat, we do the same.

	if flags & ^(AT_SYMLINK_NOFOLLOW|AT_EACCESS) != 0 {
		return EINVAL
	}

	var st Stat_t
	if err := Fstatat(dirfd, path, &st, flags&AT_SYMLINK_NOFOLLOW); err != nil {
		return err
	}

	mode &= 7
	if mode == 0 {
		return nil
	}

	var uid int
	if flags&AT_EACCESS != 0 {
		uid = Geteuid()
		if uid != 0 && isCapDacOverrideSet() {
			// If CAP_DAC_OVERRIDE is set, file access check is
			// done by the kernel in the same way as for root
			// (see generic_permission() in the Linux sources).
			uid = 0
		}
	} else {
		uid = Getuid()
	}

	if uid == 0 {
		if mode&1 == 0 {
			// Root can read and write any file.
			return nil
		}
		if st.Mode&0111 != 0 {
			// Root can execute any file that anybody can execute.
			return nil
		}
		return EACCES
	}

	var fmode uint32
	if uint32(uid) == st.Uid {
		fmode = (st.Mode >> 6) & 7
	} else {
		var gid int
		if flags&AT_EACCESS != 0 {
			gid = Getegid()
		} else {
			gid = Getgid()
		}

		if uint32(gid) == st.Gid || isGroupMember(int(st.Gid)) {
			fmode = (st.Mode >> 3) & 7
		} else {
			fmode = st.Mode & 7
		}
	}

	if fmode&mode == mode {
		return nil
	}

	return EACCES
}

//sys	nameToHandleAt(dirFD int, pathname string, fh *fileHandle, mountID *_C_int, flags int) (err error) = SYS_NAME_TO_HANDLE_AT
//sys	openByHandleAt(mountFD int, fh *fileHandle, flags int) (fd int, err error) = SYS_OPEN_BY_HANDLE_AT

// fileHandle is the argument to nameToHandleAt and openByHandleAt. We
// originally tried to generate it via unix/linux/types.go with "type
// fileHandle C.struct_file_handle" but that generated empty structs
// for mips64 and mips64le. Instead, hard code it for now (it's the
// same everywhere else) until the mips64 generator issue is fixed.
type fileHandle struct {
	Bytes uint32
	Type  int32
}

// FileHandle represents the C struct file_handle used by
// name_to_handle_at (see NameToHandleAt) and open_by_handle_at (see
// OpenByHandleAt).
type FileHandle struct {
	*fileHandle
}

// NewFileHandle constructs a FileHandle.
func NewFileHandle(handleType int32, handle []byte) FileHandle {
	const hdrSize = unsafe.Sizeof(fileHandle{})
	buf := make([]byte, hdrSize+uintptr(len(handle)))
	copy(buf[hdrSize:], handle)
	fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
	fh.Type = handleType
	fh.Bytes = uint32(len(handle))
	return FileHandle{fh}
}

func (fh *FileHandle) Size() int   { return int(fh.fileHandle.Bytes) }
func (fh *FileHandle) Type() int32 { return fh.fileHandle.Type }
func (fh *FileHandle) Bytes() []byte {
	n := fh.Size()
	if n == 0 {
		return nil
	}
	return unsafe.Slice((*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(&fh.fileHandle.Type))+4)), n)
}

// NameToHandleAt wraps the name_to_handle_at system call; it obtains
// a handle for a path name.
func NameToHandleAt(dirfd int, path string, flags int) (handle FileHandle, mountID int, err error) {
	var mid _C_int
	// Try first with a small buffer, assuming the handle will
	// only be 32 bytes.
	size := uint32(32 + unsafe.Sizeof(fileHandle{}))
	didResize := false
	for {
		buf := make([]byte, size)
		fh := (*fileHandle)(unsafe.Pointer(&buf[0]))
		fh.Bytes = size - uint32(unsafe.Sizeof(fileHandle{}))
		err = nameToHandleAt(dirfd, path, fh, &mid, flags)
		if err == EOVERFLOW {
			if didResize {
				// We shouldn't need to resize more than once
				return
			}
			didResize = true
			size = fh.Bytes + uint32(unsafe.Sizeof(fileHandle{}))
			continue
		}
		if err != nil {
			return
		}
		return FileHandle{fh}, int(mid), nil
	}
}

// OpenByHandleAt wraps the open_by_handle_at system call; it opens a
// file via a handle as previously returned by NameToHandleAt.
func OpenByHandleAt(mountFD int, handle FileHandle, flags int) (fd int, err error) {
	return openByHandleAt(mountFD, handle.fileHandle, flags)
}

// Klogset wraps the sys_syslog system call; it sets console_loglevel to
// the value specified by arg and passes a dummy pointer to bufp.
func Klogset(typ int, arg int) (err error) {
	var p unsafe.Pointer
	_, _, errno := Syscall(SYS_SYSLOG, uintptr(typ), uintptr(p), uintptr(arg))
	if errno != 0 {
		return errnoErr(errno)
	}
	return nil
}

// RemoteIovec is Iovec with the pointer replaced with an integer.
// It is used for ProcessVMReadv and ProcessVMWritev, where the pointer
// refers to a location in a different process' address space, which
// would confuse the Go garbage collector.
type RemoteIovec struct {
	Base uintptr
	Len  int
}

//sys	ProcessVMReadv(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_READV
//sys	ProcessVMWritev(pid int, localIov []Iovec, remoteIov []RemoteIovec, flags uint) (n int, err error) = SYS_PROCESS_VM_WRITEV

//sys	PidfdOpen(pid int, flags int) (fd int, err error) = SYS_PIDFD_OPEN
//sys	PidfdGetfd(pidfd int, targetfd int, flags int) (fd int, err error) = SYS_PIDFD_GETFD
//sys	PidfdSendSignal(pidfd int, sig Signal, info *Siginfo, flags int) (err error) = SYS_PIDFD_SEND_SIGNAL

//sys	shmat(id int, addr uintptr, flag int) (ret uintptr, err error)
//sys	shmctl(id int, cmd int, buf *SysvShmDesc) (result int, err error)
//sys	shmdt(addr uintptr) (err error)
//sys	shmget(key int, size int, flag int) (id int, err error)

//sys	getitimer(which int, currValue *Itimerval) (err error)
//sys	setitimer(which int, newValue *Itimerval, oldValue *Itimerval) (err error)

// MakeItimerval creates an Itimerval from interval and value durations.
func MakeItimerval(interval, value time.Duration) Itimerval {
	return Itimerval{
		Interval: NsecToTimeval(interval.Nanoseconds()),
		Value:    NsecToTimeval(value.Nanoseconds()),
	}
}

// A value which may be passed to the which parameter for Getitimer and
// Setitimer.
type ItimerWhich int

// Possible which values for Getitimer and Setitimer.
const (
	ItimerReal    ItimerWhich = ITIMER_REAL
	ItimerVirtual ItimerWhich = ITIMER_VIRTUAL
	ItimerProf    ItimerWhich = ITIMER_PROF
)

// Getitimer wraps getitimer(2) to return the current value of the timer
// specified by which.
func Getitimer(which ItimerWhich) (Itimerval, error) {
	var it Itimerval
	if err := getitimer(int(which), &it); err != nil {
		return Itimerval{}, err
	}

	return it, nil
}

// Setitimer wraps setitimer(2) to arm or disarm the timer specified by which.
// It returns the previous value of the timer.
//
// If the Itimerval argument is the zero value, the timer will be disarmed.
func Setitimer(which ItimerWhich, it Itimerval) (Itimerval, error) {
	var prev Itimerval
	if err := setitimer(int(which), &it, &prev); err != nil {
		return Itimerval{}, err
	}

	return prev, nil
}

//sysnb	rtSigprocmask(how int, set *Sigset_t, oldset *Sigset_t, sigsetsize uintptr) (err error) = SYS_RT_SIGPROCMASK

func PthreadSigmask(how int, set, oldset *Sigset_t) error {
	if oldset != nil {
		// Explicitly clear in case Sigset_t is larger than _C__NSIG.
		*oldset = Sigset_t{}
	}
	return rtSigprocmask(how, set, oldset, _C__NSIG/8)
}

//sysnb	getresuid(ruid *_C_int, euid *_C_int, suid *_C_int)
//sysnb	getresgid(rgid *_C_int, egid *_C_int, sgid *_C_int)

func Getresuid() (ruid, euid, suid int) {
	var r, e, s _C_int
	getresuid(&r, &e, &s)
	return int(r), int(e), int(s)
}

func Getresgid() (rgid, egid, sgid int) {
	var r, e, s _C_int
	getresgid(&r, &e, &s)
	return int(r), int(e), int(s)
}

// Pselect is a wrapper around the Linux pselect6 system call.
// This version does not modify the timeout argument.
func Pselect(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timespec, sigmask *Sigset_t) (n int, err error) {
	// Per https://man7.org/linux/man-pages/man2/select.2.html#NOTES,
	// The Linux pselect6() system call modifies its timeout argument.
	// [Not modifying the argument] is the behavior required by POSIX.1-2001.
	var mutableTimeout *Timespec
	if timeout != nil {
		mutableTimeout = new(Timespec)
		*mutableTimeout = *timeout
	}

	// The final argument of the pselect6() system call is not a
	// sigset_t * pointer, but is instead a structure
	var kernelMask *sigset_argpack
	if sigmask != nil {
		wordBits := 32 << (^uintptr(0) >> 63) // see math.intSize

		// A sigset stores one bit per signal,
		// offset by 1 (because signal 0 does not exist).
		// So the number of words needed is ⌈__C_NSIG - 1 / wordBits⌉.
		sigsetWords := (_C__NSIG - 1 + wordBits - 1) / (wordBits)

		sigsetBytes := uintptr(sigsetWords * (wordBits / 8))
		kernelMask = &sigset_argpack{
			ss:    sigmask,
			ssLen: sigsetBytes,
		}
	}

	return pselect6(nfd, r, w, e, mutableTimeout, kernelMask)
}

//sys	schedSetattr(pid int, attr *SchedAttr, flags uint) (err error)
//sys	schedGetattr(pid int, attr *SchedAttr, size uint, flags uint) (err error)

// SchedSetAttr is a wrapper for sched_setattr(2) syscall.
// https://man7.org/linux/man-pages/man2/sched_setattr.2.html
func SchedSetAttr(pid int, attr *SchedAttr, flags uint) error {
	if attr == nil {
		return EINVAL
	}
	attr.Size = SizeofSchedAttr
	return schedSetattr(pid, attr, flags)
}

// SchedGetAttr is a wrapper for sched_getattr(2) syscall.
// https://man7.org/linux/man-pages/man2/sched_getattr.2.html
func SchedGetAttr(pid int, flags uint) (*SchedAttr, error) {
	attr := &SchedAttr{}
	if err := schedGetattr(pid, attr, SizeofSchedAttr, flags); err != nil {
		return nil, err
	}
	return attr, nil
}

//sys	Cachestat(fd uint, crange *CachestatRange, cstat *Cachestat_t, flags uint) (err error)
//sys	Mseal(b []byte, flags uint) (err error)