aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/tools/python3/src/Modules/signalmodule.c
blob: 8305f64020335b1375655fc55edfeb37ac943f2d (plain) (blame)
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
/* Signal module -- many thanks to Lance Ellinghaus */

/* XXX Signals should be recorded per thread, now we have thread state. */

#include "Python.h"
#include "pycore_atomic.h"        // _Py_atomic_int
#include "pycore_call.h"          // _PyObject_Call()
#include "pycore_ceval.h"         // _PyEval_SignalReceived()
#include "pycore_emscripten_signal.h"  // _Py_CHECK_EMSCRIPTEN_SIGNALS
#include "pycore_fileutils.h"     // _Py_BEGIN_SUPPRESS_IPH
#include "pycore_frame.h"         // _PyInterpreterFrame
#include "pycore_moduleobject.h"  // _PyModule_GetState()
#include "pycore_pyerrors.h"      // _PyErr_SetString()
#include "pycore_pystate.h"       // _PyThreadState_GET()
#include "pycore_signal.h"        // Py_NSIG

#ifndef MS_WINDOWS
#  include "posixmodule.h"
#endif
#ifdef MS_WINDOWS
#  include "socketmodule.h"   /* needed for SOCKET_T */
#endif

#ifdef MS_WINDOWS
#  include <windows.h>
#  ifdef HAVE_PROCESS_H
#    include <process.h>
#  endif
#endif

#ifdef HAVE_SIGNAL_H
#  include <signal.h>
#endif
#ifdef HAVE_SYS_SYSCALL_H
#  include <sys/syscall.h>
#endif
#ifdef HAVE_SYS_STAT_H
#  include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TIME_H
#  include <sys/time.h>
#endif

#if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK)
#  define PYPTHREAD_SIGMASK
#endif

#if defined(PYPTHREAD_SIGMASK) && defined(HAVE_PTHREAD_H)
#  include <pthread.h>
#endif

#ifndef SIG_ERR
#  define SIG_ERR ((PyOS_sighandler_t)(-1))
#endif

#include "clinic/signalmodule.c.h"

/*[clinic input]
module signal
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=b0301a3bde5fe9d3]*/

#ifdef HAVE_SETSIG_T

/*[python input]

class sigset_t_converter(CConverter):
    type = 'sigset_t'
    converter = '_Py_Sigset_Converter'

[python start generated code]*/
/*[python end generated code: output=da39a3ee5e6b4b0d input=b5689d14466b6823]*/
#endif

/*
   NOTES ON THE INTERACTION BETWEEN SIGNALS AND THREADS

   We want the following semantics:

   - only the main thread can set a signal handler
   - only the main thread runs the signal handler
   - signals can be delivered to any thread
   - any thread can get a signal handler

   I.e. we don't support "synchronous signals" like SIGFPE (catching
   this doesn't make much sense in Python anyway) nor do we support
   signals as a means of inter-thread communication, since not all
   thread implementations support that (at least our thread library
   doesn't).

   We still have the problem that in some implementations signals
   generated by the keyboard (e.g. SIGINT) are delivered to all
   threads (e.g. SGI), while in others (e.g. Solaris) such signals are
   delivered to one random thread. On Linux, signals are delivered to
   the main thread (unless the main thread is blocking the signal, for
   example because it's already handling the same signal).  Since we
   allow signals to be delivered to any thread, this works fine. The
   only oddity is that the thread executing the Python signal handler
   may not be the thread that received the signal.
*/

static volatile struct {
    _Py_atomic_int tripped;
    /* func is atomic to ensure that PyErr_SetInterrupt is async-signal-safe
     * (even though it would probably be otherwise, anyway).
     */
    _Py_atomic_address func;
} Handlers[Py_NSIG];

#ifdef MS_WINDOWS
#define INVALID_FD ((SOCKET_T)-1)

static volatile struct {
    SOCKET_T fd;
    int warn_on_full_buffer;
    int use_send;
} wakeup = {.fd = INVALID_FD, .warn_on_full_buffer = 1, .use_send = 0};
#else
#define INVALID_FD (-1)
static volatile struct {
#ifdef __VXWORKS__
    int fd;
#else
    sig_atomic_t fd;
#endif
    int warn_on_full_buffer;
} wakeup = {.fd = INVALID_FD, .warn_on_full_buffer = 1};
#endif

/* Speed up sigcheck() when none tripped */
static _Py_atomic_int is_tripped;

typedef struct {
    PyObject *default_handler;
    PyObject *ignore_handler;
#ifdef MS_WINDOWS
    HANDLE sigint_event;
#endif
} signal_state_t;

// State shared by all Python interpreters
static signal_state_t signal_global_state = {0};

#if defined(HAVE_GETITIMER) || defined(HAVE_SETITIMER)
#  define PYHAVE_ITIMER_ERROR
#endif

typedef struct {
    PyObject *default_handler;  // borrowed ref (signal_global_state)
    PyObject *ignore_handler;  // borrowed ref (signal_global_state)
#ifdef PYHAVE_ITIMER_ERROR
    PyObject *itimer_error;
#endif
    PyTypeObject *siginfo_type;
} _signal_module_state;


Py_LOCAL_INLINE(PyObject *)
get_handler(int i)
{
    return (PyObject *)_Py_atomic_load(&Handlers[i].func);
}

Py_LOCAL_INLINE(void)
set_handler(int i, PyObject* func)
{
    _Py_atomic_store(&Handlers[i].func, (uintptr_t)func);
}


static inline _signal_module_state*
get_signal_state(PyObject *module)
{
    void *state = _PyModule_GetState(module);
    assert(state != NULL);
    return (_signal_module_state *)state;
}


static inline int
compare_handler(PyObject *func, PyObject *dfl_ign_handler)
{
    // See https://github.com/python/cpython/pull/102399
    if (func == NULL || dfl_ign_handler == NULL) {
        return 0;
    }
    assert(PyLong_CheckExact(dfl_ign_handler));
    if (!PyLong_CheckExact(func)) {
        return 0;
    }
    // Assume that comparison of two PyLong objects will never fail.
    return PyObject_RichCompareBool(func, dfl_ign_handler, Py_EQ) == 1;
}

#ifdef HAVE_SETITIMER
/* auxiliary function for setitimer */
static int
timeval_from_double(PyObject *obj, struct timeval *tv)
{
    if (obj == NULL) {
        tv->tv_sec = 0;
        tv->tv_usec = 0;
        return 0;
    }

    _PyTime_t t;
    if (_PyTime_FromSecondsObject(&t, obj, _PyTime_ROUND_CEILING) < 0) {
        return -1;
    }
    return _PyTime_AsTimeval(t, tv, _PyTime_ROUND_CEILING);
}
#endif

#if defined(HAVE_SETITIMER) || defined(HAVE_GETITIMER)
/* auxiliary functions for get/setitimer */
Py_LOCAL_INLINE(double)
double_from_timeval(struct timeval *tv)
{
    return tv->tv_sec + (double)(tv->tv_usec / 1000000.0);
}

static PyObject *
itimer_retval(struct itimerval *iv)
{
    PyObject *r, *v;

    r = PyTuple_New(2);
    if (r == NULL)
        return NULL;

    if(!(v = PyFloat_FromDouble(double_from_timeval(&iv->it_value)))) {
        Py_DECREF(r);
        return NULL;
    }

    PyTuple_SET_ITEM(r, 0, v);

    if(!(v = PyFloat_FromDouble(double_from_timeval(&iv->it_interval)))) {
        Py_DECREF(r);
        return NULL;
    }

    PyTuple_SET_ITEM(r, 1, v);

    return r;
}
#endif

/*[clinic input]
signal.default_int_handler
    signalnum: int
    frame: object
    /

The default handler for SIGINT installed by Python.

It raises KeyboardInterrupt.
[clinic start generated code]*/

static PyObject *
signal_default_int_handler_impl(PyObject *module, int signalnum,
                                PyObject *frame)
/*[clinic end generated code: output=bb11c2eb115ace4e input=efcd4a56a207acfd]*/
{
    PyErr_SetNone(PyExc_KeyboardInterrupt);
    return NULL;
}


static int
report_wakeup_write_error(void *data)
{
    PyObject *exc, *val, *tb;
    int save_errno = errno;
    errno = (int) (intptr_t) data;
    PyErr_Fetch(&exc, &val, &tb);
    PyErr_SetFromErrno(PyExc_OSError);
    PySys_WriteStderr("Exception ignored when trying to write to the "
                      "signal wakeup fd:\n");
    PyErr_WriteUnraisable(NULL);
    PyErr_Restore(exc, val, tb);
    errno = save_errno;
    return 0;
}

#ifdef MS_WINDOWS
static int
report_wakeup_send_error(void* data)
{
    PyObject *exc, *val, *tb;
    PyErr_Fetch(&exc, &val, &tb);
    /* PyErr_SetExcFromWindowsErr() invokes FormatMessage() which
       recognizes the error codes used by both GetLastError() and
       WSAGetLastError */
    PyErr_SetExcFromWindowsErr(PyExc_OSError, (int) (intptr_t) data);
    PySys_WriteStderr("Exception ignored when trying to send to the "
                      "signal wakeup fd:\n");
    PyErr_WriteUnraisable(NULL);
    PyErr_Restore(exc, val, tb);
    return 0;
}
#endif   /* MS_WINDOWS */

static void
trip_signal(int sig_num)
{
    _Py_atomic_store_relaxed(&Handlers[sig_num].tripped, 1);

    /* Set is_tripped after setting .tripped, as it gets
       cleared in PyErr_CheckSignals() before .tripped. */
    _Py_atomic_store(&is_tripped, 1);

    /* Signals are always handled by the main interpreter */
    PyInterpreterState *interp = _PyInterpreterState_Main();

    /* Notify ceval.c */
    _PyEval_SignalReceived(interp);

    /* And then write to the wakeup fd *after* setting all the globals and
       doing the _PyEval_SignalReceived. We used to write to the wakeup fd
       and then set the flag, but this allowed the following sequence of events
       (especially on windows, where trip_signal may run in a new thread):

       - main thread blocks on select([wakeup.fd], ...)
       - signal arrives
       - trip_signal writes to the wakeup fd
       - the main thread wakes up
       - the main thread checks the signal flags, sees that they're unset
       - the main thread empties the wakeup fd
       - the main thread goes back to sleep
       - trip_signal sets the flags to request the Python-level signal handler
         be run
       - the main thread doesn't notice, because it's asleep

       See bpo-30038 for more details.
    */

    int fd;
#ifdef MS_WINDOWS
    fd = Py_SAFE_DOWNCAST(wakeup.fd, SOCKET_T, int);
#else
    fd = wakeup.fd;
#endif

    if (fd != INVALID_FD) {
        unsigned char byte = (unsigned char)sig_num;
#ifdef MS_WINDOWS
        if (wakeup.use_send) {
            Py_ssize_t rc = send(fd, &byte, 1, 0);

            if (rc < 0) {
                int last_error = GetLastError();
                if (wakeup.warn_on_full_buffer ||
                    last_error != WSAEWOULDBLOCK)
                {
                    /* _PyEval_AddPendingCall() isn't signal-safe, but we
                       still use it for this exceptional case. */
                    _PyEval_AddPendingCall(interp,
                                           report_wakeup_send_error,
                                           (void *)(intptr_t) last_error);
                }
            }
        }
        else
#endif
        {
            /* _Py_write_noraise() retries write() if write() is interrupted by
               a signal (fails with EINTR). */
            Py_ssize_t rc = _Py_write_noraise(fd, &byte, 1);

            if (rc < 0) {
                if (wakeup.warn_on_full_buffer ||
                    (errno != EWOULDBLOCK && errno != EAGAIN))
                {
                    /* _PyEval_AddPendingCall() isn't signal-safe, but we
                       still use it for this exceptional case. */
                    _PyEval_AddPendingCall(interp,
                                           report_wakeup_write_error,
                                           (void *)(intptr_t)errno);
                }
            }
        }
    }
}

static void
signal_handler(int sig_num)
{
    int save_errno = errno;

    trip_signal(sig_num);

#ifndef HAVE_SIGACTION
#ifdef SIGCHLD
    /* To avoid infinite recursion, this signal remains
       reset until explicit re-instated.
       Don't clear the 'func' field as it is our pointer
       to the Python handler... */
    if (sig_num != SIGCHLD)
#endif
    /* If the handler was not set up with sigaction, reinstall it.  See
     * Python/pylifecycle.c for the implementation of PyOS_setsig which
     * makes this true.  See also issue8354. */
    PyOS_setsig(sig_num, signal_handler);
#endif

    /* Issue #10311: asynchronously executing signal handlers should not
       mutate errno under the feet of unsuspecting C code. */
    errno = save_errno;

#ifdef MS_WINDOWS
    if (sig_num == SIGINT) {
        signal_state_t *state = &signal_global_state;
        SetEvent(state->sigint_event);
    }
#endif
}


#ifdef HAVE_ALARM

/*[clinic input]
signal.alarm -> long

    seconds: int
    /

Arrange for SIGALRM to arrive after the given number of seconds.
[clinic start generated code]*/

static long
signal_alarm_impl(PyObject *module, int seconds)
/*[clinic end generated code: output=144232290814c298 input=0d5e97e0e6f39e86]*/
{
    /* alarm() returns the number of seconds remaining */
    return (long)alarm(seconds);
}

#endif

#ifdef HAVE_PAUSE

/*[clinic input]
signal.pause

Wait until a signal arrives.
[clinic start generated code]*/

static PyObject *
signal_pause_impl(PyObject *module)
/*[clinic end generated code: output=391656788b3c3929 input=f03de0f875752062]*/
{
    Py_BEGIN_ALLOW_THREADS
    (void)pause();
    Py_END_ALLOW_THREADS
    /* make sure that any exceptions that got raised are propagated
     * back into Python
     */
    if (PyErr_CheckSignals())
        return NULL;

    Py_RETURN_NONE;
}

#endif

/*[clinic input]
signal.raise_signal

    signalnum: int
    /

Send a signal to the executing process.
[clinic start generated code]*/

static PyObject *
signal_raise_signal_impl(PyObject *module, int signalnum)
/*[clinic end generated code: output=e2b014220aa6111d input=e90c0f9a42358de6]*/
{
    int err;
    Py_BEGIN_ALLOW_THREADS
    _Py_BEGIN_SUPPRESS_IPH
    err = raise(signalnum);
    _Py_END_SUPPRESS_IPH
    Py_END_ALLOW_THREADS

    if (err) {
        return PyErr_SetFromErrno(PyExc_OSError);
    }

    // If the current thread can handle signals, handle immediately
    // the raised signal.
    if (PyErr_CheckSignals()) {
        return NULL;
    }

    Py_RETURN_NONE;
}

/*[clinic input]
signal.signal

    signalnum: int
    handler:   object
    /

Set the action for the given signal.

The action can be SIG_DFL, SIG_IGN, or a callable Python object.
The previous action is returned.  See getsignal() for possible return values.

*** IMPORTANT NOTICE ***
A signal handler function is called with two arguments:
the first is the signal number, the second is the interrupted stack frame.
[clinic start generated code]*/

static PyObject *
signal_signal_impl(PyObject *module, int signalnum, PyObject *handler)
/*[clinic end generated code: output=b44cfda43780f3a1 input=deee84af5fa0432c]*/
{
    _signal_module_state *modstate = get_signal_state(module);
    PyObject *old_handler;
    void (*func)(int);
#ifdef MS_WINDOWS
    /* Validate that signalnum is one of the allowable signals */
    switch (signalnum) {
        case SIGABRT: break;
#ifdef SIGBREAK
        /* Issue #10003: SIGBREAK is not documented as permitted, but works
           and corresponds to CTRL_BREAK_EVENT. */
        case SIGBREAK: break;
#endif
        case SIGFPE: break;
        case SIGILL: break;
        case SIGINT: break;
        case SIGSEGV: break;
        case SIGTERM: break;
        default:
            PyErr_SetString(PyExc_ValueError, "invalid signal value");
            return NULL;
    }
#endif

    PyThreadState *tstate = _PyThreadState_GET();
    if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
        _PyErr_SetString(tstate, PyExc_ValueError,
                         "signal only works in main thread "
                         "of the main interpreter");
        return NULL;
    }
    if (signalnum < 1 || signalnum >= Py_NSIG) {
        _PyErr_SetString(tstate, PyExc_ValueError,
                         "signal number out of range");
        return NULL;
    }
    if (PyCallable_Check(handler)) {
        func = signal_handler;
    } else if (compare_handler(handler, modstate->ignore_handler)) {
        func = SIG_IGN;
    } else if (compare_handler(handler, modstate->default_handler)) {
        func = SIG_DFL;
    } else {
        _PyErr_SetString(tstate, PyExc_TypeError,
                         "signal handler must be signal.SIG_IGN, "
                         "signal.SIG_DFL, or a callable object");
        return NULL;
    }

    /* Check for pending signals before changing signal handler */
    if (_PyErr_CheckSignalsTstate(tstate)) {
        return NULL;
    }
    if (PyOS_setsig(signalnum, func) == SIG_ERR) {
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }

    old_handler = get_handler(signalnum);
    set_handler(signalnum, Py_NewRef(handler));

    if (old_handler != NULL) {
        return old_handler;
    }
    else {
        Py_RETURN_NONE;
    }
}


/*[clinic input]
signal.getsignal

    signalnum: int
    /

Return the current action for the given signal.

The return value can be:
  SIG_IGN -- if the signal is being ignored
  SIG_DFL -- if the default action for the signal is in effect
  None    -- if an unknown handler is in effect
  anything else -- the callable Python object used as a handler
[clinic start generated code]*/

static PyObject *
signal_getsignal_impl(PyObject *module, int signalnum)
/*[clinic end generated code: output=35b3e0e796fd555e input=ac23a00f19dfa509]*/
{
    PyObject *old_handler;
    if (signalnum < 1 || signalnum >= Py_NSIG) {
        PyErr_SetString(PyExc_ValueError,
                        "signal number out of range");
        return NULL;
    }
    old_handler = get_handler(signalnum);
    if (old_handler != NULL) {
        return Py_NewRef(old_handler);
    }
    else {
        Py_RETURN_NONE;
    }
}


/*[clinic input]
signal.strsignal

    signalnum: int
    /

Return the system description of the given signal.

Returns the description of signal *signalnum*, such as "Interrupt"
for :const:`SIGINT`. Returns :const:`None` if *signalnum* has no
description. Raises :exc:`ValueError` if *signalnum* is invalid.
[clinic start generated code]*/

static PyObject *
signal_strsignal_impl(PyObject *module, int signalnum)
/*[clinic end generated code: output=44e12e1e3b666261 input=238b335847778bc0]*/
{
    const char *res;

    if (signalnum < 1 || signalnum >= Py_NSIG) {
        PyErr_SetString(PyExc_ValueError,
                "signal number out of range");
        return NULL;
    }

#ifndef HAVE_STRSIGNAL
    switch (signalnum) {
        /* Though being a UNIX, HP-UX does not provide strsignal(3). */
#ifndef MS_WINDOWS
        case SIGHUP:
            res = "Hangup";
            break;
        case SIGALRM:
            res = "Alarm clock";
            break;
        case SIGPIPE:
            res = "Broken pipe";
            break;
        case SIGQUIT:
            res = "Quit";
            break;
        case SIGCHLD:
            res = "Child exited";
            break;
#endif
        /* Custom redefinition of POSIX signals allowed on Windows. */
        case SIGINT:
            res = "Interrupt";
            break;
        case SIGILL:
            res = "Illegal instruction";
            break;
        case SIGABRT:
            res = "Aborted";
            break;
        case SIGFPE:
            res = "Floating point exception";
            break;
        case SIGSEGV:
            res = "Segmentation fault";
            break;
        case SIGTERM:
            res = "Terminated";
            break;
        default:
            Py_RETURN_NONE;
    }
#else
    errno = 0;
    res = strsignal(signalnum);

    if (errno || res == NULL || strstr(res, "Unknown signal") != NULL)
        Py_RETURN_NONE;
#endif

    return Py_BuildValue("s", res);
}

#ifdef HAVE_SIGINTERRUPT

/*[clinic input]
signal.siginterrupt

    signalnum: int
    flag:      int
    /

Change system call restart behaviour.

If flag is False, system calls will be restarted when interrupted by
signal sig, else system calls will be interrupted.
[clinic start generated code]*/

static PyObject *
signal_siginterrupt_impl(PyObject *module, int signalnum, int flag)
/*[clinic end generated code: output=063816243d85dd19 input=4160acacca3e2099]*/
{
    if (signalnum < 1 || signalnum >= Py_NSIG) {
        PyErr_SetString(PyExc_ValueError,
                        "signal number out of range");
        return NULL;
    }
#ifdef HAVE_SIGACTION
    struct sigaction act;
    (void) sigaction(signalnum, NULL, &act);
    if (flag) {
        act.sa_flags &= ~SA_RESTART;
    }
    else {
        act.sa_flags |= SA_RESTART;
    }
    if (sigaction(signalnum, &act, NULL) < 0) {
#else
    if (siginterrupt(signalnum, flag) < 0) {
#endif
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }
    Py_RETURN_NONE;
}

#endif


static PyObject*
signal_set_wakeup_fd(PyObject *self, PyObject *args, PyObject *kwds)
{
    struct _Py_stat_struct status;
    static char *kwlist[] = {
        "", "warn_on_full_buffer", NULL,
    };
    int warn_on_full_buffer = 1;
#ifdef MS_WINDOWS
    PyObject *fdobj;
    SOCKET_T sockfd, old_sockfd;
    int res;
    int res_size = sizeof res;
    PyObject *mod;
    int is_socket;

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|$p:set_wakeup_fd", kwlist,
                                     &fdobj, &warn_on_full_buffer))
        return NULL;

    sockfd = PyLong_AsSocket_t(fdobj);
    if (sockfd == (SOCKET_T)(-1) && PyErr_Occurred())
        return NULL;
#else
    int fd;

    if (!PyArg_ParseTupleAndKeywords(args, kwds, "i|$p:set_wakeup_fd", kwlist,
                                     &fd, &warn_on_full_buffer))
        return NULL;
#endif

    PyThreadState *tstate = _PyThreadState_GET();
    if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
        _PyErr_SetString(tstate, PyExc_ValueError,
                         "set_wakeup_fd only works in main thread "
                         "of the main interpreter");
        return NULL;
    }

#ifdef MS_WINDOWS
    is_socket = 0;
    if (sockfd != INVALID_FD) {
        /* Import the _socket module to call WSAStartup() */
        mod = PyImport_ImportModule("_socket");
        if (mod == NULL)
            return NULL;
        Py_DECREF(mod);

        /* test the socket */
        if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR,
                       (char *)&res, &res_size) != 0) {
            int fd, err;

            err = WSAGetLastError();
            if (err != WSAENOTSOCK) {
                PyErr_SetExcFromWindowsErr(PyExc_OSError, err);
                return NULL;
            }

            fd = (int)sockfd;
            if ((SOCKET_T)fd != sockfd) {
                _PyErr_SetString(tstate, PyExc_ValueError, "invalid fd");
                return NULL;
            }

            if (_Py_fstat(fd, &status) != 0) {
                return NULL;
            }

            /* on Windows, a file cannot be set to non-blocking mode */
        }
        else {
            is_socket = 1;

            /* Windows does not provide a function to test if a socket
               is in non-blocking mode */
        }
    }

    old_sockfd = wakeup.fd;
    wakeup.fd = sockfd;
    wakeup.warn_on_full_buffer = warn_on_full_buffer;
    wakeup.use_send = is_socket;

    if (old_sockfd != INVALID_FD)
        return PyLong_FromSocket_t(old_sockfd);
    else
        return PyLong_FromLong(-1);
#else
    if (fd != -1) {
        int blocking;

        if (_Py_fstat(fd, &status) != 0)
            return NULL;

        blocking = _Py_get_blocking(fd);
        if (blocking < 0)
            return NULL;
        if (blocking) {
            _PyErr_Format(tstate, PyExc_ValueError,
                          "the fd %i must be in non-blocking mode",
                          fd);
            return NULL;
        }
    }

    int old_fd = wakeup.fd;
    wakeup.fd = fd;
    wakeup.warn_on_full_buffer = warn_on_full_buffer;

    return PyLong_FromLong(old_fd);
#endif
}

PyDoc_STRVAR(set_wakeup_fd_doc,
"set_wakeup_fd(fd, *, warn_on_full_buffer=True) -> fd\n\
\n\
Sets the fd to be written to (with the signal number) when a signal\n\
comes in.  A library can use this to wakeup select or poll.\n\
The previous fd or -1 is returned.\n\
\n\
The fd must be non-blocking.");

/* C API for the same, without all the error checking */
int
PySignal_SetWakeupFd(int fd)
{
    if (fd < 0) {
        fd = -1;
    }

#ifdef MS_WINDOWS
    int old_fd = Py_SAFE_DOWNCAST(wakeup.fd, SOCKET_T, int);
#else
    int old_fd = wakeup.fd;
#endif
    wakeup.fd = fd;
    wakeup.warn_on_full_buffer = 1;
    return old_fd;
}


#ifdef HAVE_SETITIMER
/*[clinic input]
signal.setitimer

    which:    int
    seconds:  object
    interval: object(c_default="NULL") = 0.0
    /

Sets given itimer (one of ITIMER_REAL, ITIMER_VIRTUAL or ITIMER_PROF).

The timer will fire after value seconds and after that every interval seconds.
The itimer can be cleared by setting seconds to zero.

Returns old values as a tuple: (delay, interval).
[clinic start generated code]*/

static PyObject *
signal_setitimer_impl(PyObject *module, int which, PyObject *seconds,
                      PyObject *interval)
/*[clinic end generated code: output=65f9dcbddc35527b input=de43daf194e6f66f]*/
{
    _signal_module_state *modstate = get_signal_state(module);

    struct itimerval new;
    if (timeval_from_double(seconds, &new.it_value) < 0) {
        return NULL;
    }
    if (timeval_from_double(interval, &new.it_interval) < 0) {
        return NULL;
    }

    /* Let OS check "which" value */
    struct itimerval old;
    if (setitimer(which, &new, &old) != 0) {
        PyErr_SetFromErrno(modstate->itimer_error);
        return NULL;
    }

    return itimer_retval(&old);
}
#endif  // HAVE_SETITIMER


#ifdef HAVE_GETITIMER
/*[clinic input]
signal.getitimer

    which:    int
    /

Returns current value of given itimer.
[clinic start generated code]*/

static PyObject *
signal_getitimer_impl(PyObject *module, int which)
/*[clinic end generated code: output=9e053175d517db40 input=f7d21d38f3490627]*/
{
    _signal_module_state *modstate = get_signal_state(module);

    struct itimerval old;
    if (getitimer(which, &old) != 0) {
        PyErr_SetFromErrno(modstate->itimer_error);
        return NULL;
    }

    return itimer_retval(&old);
}
#endif // HAVE_GETITIMER


#ifdef HAVE_SIGSET_T
#if defined(PYPTHREAD_SIGMASK) || defined(HAVE_SIGPENDING)
static PyObject*
sigset_to_set(sigset_t mask)
{
    PyObject *signum, *result;
    int sig;

    result = PySet_New(0);
    if (result == NULL)
        return NULL;

    for (sig = 1; sig < Py_NSIG; sig++) {
        if (sigismember(&mask, sig) != 1)
            continue;

        /* Handle the case where it is a member by adding the signal to
           the result list.  Ignore the other cases because they mean the
           signal isn't a member of the mask or the signal was invalid,
           and an invalid signal must have been our fault in constructing
           the loop boundaries. */
        signum = PyLong_FromLong(sig);
        if (signum == NULL) {
            Py_DECREF(result);
            return NULL;
        }
        if (PySet_Add(result, signum) == -1) {
            Py_DECREF(signum);
            Py_DECREF(result);
            return NULL;
        }
        Py_DECREF(signum);
    }
    return result;
}
#endif

#ifdef PYPTHREAD_SIGMASK

/*[clinic input]
signal.pthread_sigmask

    how:  int
    mask: sigset_t
    /

Fetch and/or change the signal mask of the calling thread.
[clinic start generated code]*/

static PyObject *
signal_pthread_sigmask_impl(PyObject *module, int how, sigset_t mask)
/*[clinic end generated code: output=0562c0fb192981a8 input=85bcebda442fa77f]*/
{
    sigset_t previous;
    int err;

    err = pthread_sigmask(how, &mask, &previous);
    if (err != 0) {
        errno = err;
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }

    /* if signals was unblocked, signal handlers have been called */
    if (PyErr_CheckSignals())
        return NULL;

    return sigset_to_set(previous);
}

#endif   /* #ifdef PYPTHREAD_SIGMASK */


#ifdef HAVE_SIGPENDING

/*[clinic input]
signal.sigpending

Examine pending signals.

Returns a set of signal numbers that are pending for delivery to
the calling thread.
[clinic start generated code]*/

static PyObject *
signal_sigpending_impl(PyObject *module)
/*[clinic end generated code: output=53375ffe89325022 input=e0036c016f874e29]*/
{
    int err;
    sigset_t mask;
    err = sigpending(&mask);
    if (err)
        return PyErr_SetFromErrno(PyExc_OSError);
    return sigset_to_set(mask);
}

#endif   /* #ifdef HAVE_SIGPENDING */


#ifdef HAVE_SIGWAIT

/*[clinic input]
signal.sigwait

    sigset: sigset_t
    /

Wait for a signal.

Suspend execution of the calling thread until the delivery of one of the
signals specified in the signal set sigset.  The function accepts the signal
and returns the signal number.
[clinic start generated code]*/

static PyObject *
signal_sigwait_impl(PyObject *module, sigset_t sigset)
/*[clinic end generated code: output=f43770699d682f96 input=a6fbd47b1086d119]*/
{
    int err, signum;

    Py_BEGIN_ALLOW_THREADS
    err = sigwait(&sigset, &signum);
    Py_END_ALLOW_THREADS
    if (err) {
        errno = err;
        return PyErr_SetFromErrno(PyExc_OSError);
    }

    return PyLong_FromLong(signum);
}

#endif   /* #ifdef HAVE_SIGWAIT */
#endif   /* #ifdef HAVE_SIGSET_T */

#if (defined(HAVE_SIGFILLSET) && defined(HAVE_SIGSET_T)) || defined(MS_WINDOWS)

/*[clinic input]
signal.valid_signals

Return a set of valid signal numbers on this platform.

The signal numbers returned by this function can be safely passed to
functions like `pthread_sigmask`.
[clinic start generated code]*/

static PyObject *
signal_valid_signals_impl(PyObject *module)
/*[clinic end generated code: output=1609cffbcfcf1314 input=86a3717ff25288f2]*/
{
#ifdef MS_WINDOWS
#ifdef SIGBREAK
    PyObject *tup = Py_BuildValue("(iiiiiii)", SIGABRT, SIGBREAK, SIGFPE,
                                  SIGILL, SIGINT, SIGSEGV, SIGTERM);
#else
    PyObject *tup = Py_BuildValue("(iiiiii)", SIGABRT, SIGFPE, SIGILL,
                                  SIGINT, SIGSEGV, SIGTERM);
#endif
    if (tup == NULL) {
        return NULL;
    }
    PyObject *set = PySet_New(tup);
    Py_DECREF(tup);
    return set;
#else
    sigset_t mask;
    if (sigemptyset(&mask) || sigfillset(&mask)) {
        return PyErr_SetFromErrno(PyExc_OSError);
    }
    return sigset_to_set(mask);
#endif
}

#endif   /* #if (defined(HAVE_SIGFILLSET) && defined(HAVE_SIGSET_T)) || defined(MS_WINDOWS) */



#if defined(HAVE_SIGWAITINFO) || defined(HAVE_SIGTIMEDWAIT)
static PyStructSequence_Field struct_siginfo_fields[] = {
    {"si_signo",        "signal number"},
    {"si_code",         "signal code"},
    {"si_errno",        "errno associated with this signal"},
    {"si_pid",          "sending process ID"},
    {"si_uid",          "real user ID of sending process"},
    {"si_status",       "exit value or signal"},
    {"si_band",         "band event for SIGPOLL"},
    {0}
};

PyDoc_STRVAR(struct_siginfo__doc__,
"struct_siginfo: Result from sigwaitinfo or sigtimedwait.\n\n\
This object may be accessed either as a tuple of\n\
(si_signo, si_code, si_errno, si_pid, si_uid, si_status, si_band),\n\
or via the attributes si_signo, si_code, and so on.");

static PyStructSequence_Desc struct_siginfo_desc = {
    "signal.struct_siginfo",           /* name */
    struct_siginfo__doc__,       /* doc */
    struct_siginfo_fields,       /* fields */
    7          /* n_in_sequence */
};


static PyObject *
fill_siginfo(_signal_module_state *state, siginfo_t *si)
{
    PyObject *result = PyStructSequence_New(state->siginfo_type);
    if (!result)
        return NULL;

    PyStructSequence_SET_ITEM(result, 0, PyLong_FromLong((long)(si->si_signo)));
    PyStructSequence_SET_ITEM(result, 1, PyLong_FromLong((long)(si->si_code)));
#ifdef __VXWORKS__
    PyStructSequence_SET_ITEM(result, 2, PyLong_FromLong(0L));
    PyStructSequence_SET_ITEM(result, 3, PyLong_FromLong(0L));
    PyStructSequence_SET_ITEM(result, 4, PyLong_FromLong(0L));
    PyStructSequence_SET_ITEM(result, 5, PyLong_FromLong(0L));
#else
    PyStructSequence_SET_ITEM(result, 2, PyLong_FromLong((long)(si->si_errno)));
    PyStructSequence_SET_ITEM(result, 3, PyLong_FromPid(si->si_pid));
    PyStructSequence_SET_ITEM(result, 4, _PyLong_FromUid(si->si_uid));
    PyStructSequence_SET_ITEM(result, 5,
                                PyLong_FromLong((long)(si->si_status)));
#endif
#ifdef HAVE_SIGINFO_T_SI_BAND
    PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(si->si_band));
#else
    PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(0L));
#endif
    if (PyErr_Occurred()) {
        Py_DECREF(result);
        return NULL;
    }

    return result;
}
#endif

#ifdef HAVE_SIGSET_T
#ifdef HAVE_SIGWAITINFO

/*[clinic input]
signal.sigwaitinfo

    sigset: sigset_t
    /

Wait synchronously until one of the signals in *sigset* is delivered.

Returns a struct_siginfo containing information about the signal.
[clinic start generated code]*/

static PyObject *
signal_sigwaitinfo_impl(PyObject *module, sigset_t sigset)
/*[clinic end generated code: output=1eb2f1fa236fdbca input=3d1a7e1f27fc664c]*/
{
    siginfo_t si;
    int err;
    int async_err = 0;

    do {
        Py_BEGIN_ALLOW_THREADS
        err = sigwaitinfo(&sigset, &si);
        Py_END_ALLOW_THREADS
    } while (err == -1
             && errno == EINTR && !(async_err = PyErr_CheckSignals()));
    if (err == -1)
        return (!async_err) ? PyErr_SetFromErrno(PyExc_OSError) : NULL;

    _signal_module_state *state = get_signal_state(module);
    return fill_siginfo(state, &si);
}

#endif   /* #ifdef HAVE_SIGWAITINFO */

#ifdef HAVE_SIGTIMEDWAIT

/*[clinic input]
signal.sigtimedwait

    sigset: sigset_t
    timeout as timeout_obj: object
    /

Like sigwaitinfo(), but with a timeout.

The timeout is specified in seconds, with floating point numbers allowed.
[clinic start generated code]*/

static PyObject *
signal_sigtimedwait_impl(PyObject *module, sigset_t sigset,
                         PyObject *timeout_obj)
/*[clinic end generated code: output=59c8971e8ae18a64 input=87fd39237cf0b7ba]*/
{
    _PyTime_t timeout;
    if (_PyTime_FromSecondsObject(&timeout,
                                  timeout_obj, _PyTime_ROUND_CEILING) < 0)
        return NULL;

    if (timeout < 0) {
        PyErr_SetString(PyExc_ValueError, "timeout must be non-negative");
        return NULL;
    }

    _PyTime_t deadline = _PyDeadline_Init(timeout);
    siginfo_t si;

    do {
        struct timespec ts;
        if (_PyTime_AsTimespec(timeout, &ts) < 0) {
            return NULL;
        }

        int res;
        Py_BEGIN_ALLOW_THREADS
        res = sigtimedwait(&sigset, &si, &ts);
        Py_END_ALLOW_THREADS

        if (res != -1)
            break;

        if (errno != EINTR) {
            if (errno == EAGAIN)
                Py_RETURN_NONE;
            else
                return PyErr_SetFromErrno(PyExc_OSError);
        }

        /* sigtimedwait() was interrupted by a signal (EINTR) */
        if (PyErr_CheckSignals())
            return NULL;

        timeout = _PyDeadline_Get(deadline);
        if (timeout < 0) {
            break;
        }
    } while (1);

    _signal_module_state *state = get_signal_state(module);
    return fill_siginfo(state, &si);
}

#endif   /* #ifdef HAVE_SIGTIMEDWAIT */
#endif   /* #ifdef HAVE_SIGSET_T */


#if defined(HAVE_PTHREAD_KILL)

/*[clinic input]
signal.pthread_kill

    thread_id:  unsigned_long(bitwise=True)
    signalnum:  int
    /

Send a signal to a thread.
[clinic start generated code]*/

static PyObject *
signal_pthread_kill_impl(PyObject *module, unsigned long thread_id,
                         int signalnum)
/*[clinic end generated code: output=7629919b791bc27f input=1d901f2c7bb544ff]*/
{
    int err;

    if (PySys_Audit("signal.pthread_kill", "ki", thread_id, signalnum) < 0) {
        return NULL;
    }

    err = pthread_kill((pthread_t)thread_id, signalnum);
    if (err != 0) {
        errno = err;
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }

    /* the signal may have been send to the current thread */
    if (PyErr_CheckSignals())
        return NULL;

    Py_RETURN_NONE;
}

#endif   /* #if defined(HAVE_PTHREAD_KILL) */


#if defined(__linux__) && defined(__NR_pidfd_send_signal)
/*[clinic input]
signal.pidfd_send_signal

    pidfd: int
    signalnum: int
    siginfo: object = None
    flags: int = 0
    /

Send a signal to a process referred to by a pid file descriptor.
[clinic start generated code]*/

static PyObject *
signal_pidfd_send_signal_impl(PyObject *module, int pidfd, int signalnum,
                              PyObject *siginfo, int flags)
/*[clinic end generated code: output=2d59f04a75d9cbdf input=2a6543a1f4ac2000]*/

{
    if (siginfo != Py_None) {
        PyErr_SetString(PyExc_TypeError, "siginfo must be None");
        return NULL;
    }
    if (syscall(__NR_pidfd_send_signal, pidfd, signalnum, NULL, flags) < 0) {
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }
    Py_RETURN_NONE;
}
#endif



/* List of functions defined in the module -- some of the methoddefs are
   defined to nothing if the corresponding C function is not available. */
static PyMethodDef signal_methods[] = {
    SIGNAL_DEFAULT_INT_HANDLER_METHODDEF
    SIGNAL_ALARM_METHODDEF
    SIGNAL_SETITIMER_METHODDEF
    SIGNAL_GETITIMER_METHODDEF
    SIGNAL_SIGNAL_METHODDEF
    SIGNAL_RAISE_SIGNAL_METHODDEF
    SIGNAL_STRSIGNAL_METHODDEF
    SIGNAL_GETSIGNAL_METHODDEF
    {"set_wakeup_fd", _PyCFunction_CAST(signal_set_wakeup_fd), METH_VARARGS | METH_KEYWORDS, set_wakeup_fd_doc},
    SIGNAL_SIGINTERRUPT_METHODDEF
    SIGNAL_PAUSE_METHODDEF
    SIGNAL_PIDFD_SEND_SIGNAL_METHODDEF
    SIGNAL_PTHREAD_KILL_METHODDEF
    SIGNAL_PTHREAD_SIGMASK_METHODDEF
    SIGNAL_SIGPENDING_METHODDEF
    SIGNAL_SIGWAIT_METHODDEF
    SIGNAL_SIGWAITINFO_METHODDEF
    SIGNAL_SIGTIMEDWAIT_METHODDEF
#if defined(HAVE_SIGFILLSET) || defined(MS_WINDOWS)
    SIGNAL_VALID_SIGNALS_METHODDEF
#endif
    {NULL, NULL}           /* sentinel */
};


PyDoc_STRVAR(module_doc,
"This module provides mechanisms to use signal handlers in Python.\n\
\n\
Functions:\n\
\n\
alarm() -- cause SIGALRM after a specified time [Unix only]\n\
setitimer() -- cause a signal (described below) after a specified\n\
               float time and the timer may restart then [Unix only]\n\
getitimer() -- get current value of timer [Unix only]\n\
signal() -- set the action for a given signal\n\
getsignal() -- get the signal action for a given signal\n\
pause() -- wait until a signal arrives [Unix only]\n\
default_int_handler() -- default SIGINT handler\n\
\n\
signal constants:\n\
SIG_DFL -- used to refer to the system default handler\n\
SIG_IGN -- used to ignore the signal\n\
NSIG -- number of defined signals\n\
SIGINT, SIGTERM, etc. -- signal numbers\n\
\n\
itimer constants:\n\
ITIMER_REAL -- decrements in real time, and delivers SIGALRM upon\n\
               expiration\n\
ITIMER_VIRTUAL -- decrements only when the process is executing,\n\
               and delivers SIGVTALRM upon expiration\n\
ITIMER_PROF -- decrements both when the process is executing and\n\
               when the system is executing on behalf of the process.\n\
               Coupled with ITIMER_VIRTUAL, this timer is usually\n\
               used to profile the time spent by the application\n\
               in user and kernel space. SIGPROF is delivered upon\n\
               expiration.\n\
\n\n\
*** IMPORTANT NOTICE ***\n\
A signal handler function is called with two arguments:\n\
the first is the signal number, the second is the interrupted stack frame.");



static int
signal_add_constants(PyObject *module)
{
    if (PyModule_AddIntConstant(module, "NSIG", Py_NSIG) < 0) {
        return -1;
    }

#define ADD_INT_MACRO(macro) \
    if (PyModule_AddIntConstant(module, #macro, macro) < 0) { \
        return -1; \
    }

    // SIG_xxx pthread_sigmask() constants
#ifdef SIG_BLOCK
    ADD_INT_MACRO(SIG_BLOCK);
#endif
#ifdef SIG_UNBLOCK
    ADD_INT_MACRO(SIG_UNBLOCK);
#endif
#ifdef SIG_SETMASK
    ADD_INT_MACRO(SIG_SETMASK);
#endif

    // SIGxxx signal number constants
#ifdef SIGHUP
    ADD_INT_MACRO(SIGHUP);
#endif
#ifdef SIGINT
    ADD_INT_MACRO(SIGINT);
#endif
#ifdef SIGBREAK
    ADD_INT_MACRO(SIGBREAK);
#endif
#ifdef SIGQUIT
    ADD_INT_MACRO(SIGQUIT);
#endif
#ifdef SIGILL
    ADD_INT_MACRO(SIGILL);
#endif
#ifdef SIGTRAP
    ADD_INT_MACRO(SIGTRAP);
#endif
#ifdef SIGIOT
    ADD_INT_MACRO(SIGIOT);
#endif
#ifdef SIGABRT
    ADD_INT_MACRO(SIGABRT);
#endif
#ifdef SIGEMT
    ADD_INT_MACRO(SIGEMT);
#endif
#ifdef SIGFPE
    ADD_INT_MACRO(SIGFPE);
#endif
#ifdef SIGKILL
    ADD_INT_MACRO(SIGKILL);
#endif
#ifdef SIGBUS
    ADD_INT_MACRO(SIGBUS);
#endif
#ifdef SIGSEGV
    ADD_INT_MACRO(SIGSEGV);
#endif
#ifdef SIGSYS
    ADD_INT_MACRO(SIGSYS);
#endif
#ifdef SIGPIPE
    ADD_INT_MACRO(SIGPIPE);
#endif
#ifdef SIGALRM
    ADD_INT_MACRO(SIGALRM);
#endif
#ifdef SIGTERM
    ADD_INT_MACRO(SIGTERM);
#endif
#ifdef SIGUSR1
    ADD_INT_MACRO(SIGUSR1);
#endif
#ifdef SIGUSR2
    ADD_INT_MACRO(SIGUSR2);
#endif
#ifdef SIGCLD
    ADD_INT_MACRO(SIGCLD);
#endif
#ifdef SIGCHLD
    ADD_INT_MACRO(SIGCHLD);
#endif
#ifdef SIGPWR
    ADD_INT_MACRO(SIGPWR);
#endif
#ifdef SIGIO
    ADD_INT_MACRO(SIGIO);
#endif
#ifdef SIGURG
    ADD_INT_MACRO(SIGURG);
#endif
#ifdef SIGWINCH
    ADD_INT_MACRO(SIGWINCH);
#endif
#ifdef SIGPOLL
    ADD_INT_MACRO(SIGPOLL);
#endif
#ifdef SIGSTOP
    ADD_INT_MACRO(SIGSTOP);
#endif
#ifdef SIGTSTP
    ADD_INT_MACRO(SIGTSTP);
#endif
#ifdef SIGCONT
    ADD_INT_MACRO(SIGCONT);
#endif
#ifdef SIGTTIN
    ADD_INT_MACRO(SIGTTIN);
#endif
#ifdef SIGTTOU
    ADD_INT_MACRO(SIGTTOU);
#endif
#ifdef SIGVTALRM
    ADD_INT_MACRO(SIGVTALRM);
#endif
#ifdef SIGPROF
    ADD_INT_MACRO(SIGPROF);
#endif
#ifdef SIGXCPU
    ADD_INT_MACRO(SIGXCPU);
#endif
#ifdef SIGXFSZ
    ADD_INT_MACRO(SIGXFSZ);
#endif
#ifdef SIGRTMIN
    ADD_INT_MACRO(SIGRTMIN);
#endif
#ifdef SIGRTMAX
    ADD_INT_MACRO(SIGRTMAX);
#endif
#ifdef SIGINFO
    ADD_INT_MACRO(SIGINFO);
#endif
#ifdef SIGSTKFLT
    ADD_INT_MACRO(SIGSTKFLT);
#endif

    // ITIMER_xxx constants
#ifdef ITIMER_REAL
    ADD_INT_MACRO(ITIMER_REAL);
#endif
#ifdef ITIMER_VIRTUAL
    ADD_INT_MACRO(ITIMER_VIRTUAL);
#endif
#ifdef ITIMER_PROF
    ADD_INT_MACRO(ITIMER_PROF);
#endif

    // CTRL_xxx Windows signals
#ifdef CTRL_C_EVENT
    ADD_INT_MACRO(CTRL_C_EVENT);
#endif
#ifdef CTRL_BREAK_EVENT
    ADD_INT_MACRO(CTRL_BREAK_EVENT);
#endif

    return 0;

#undef ADD_INT_MACRO
}


static int
signal_get_set_handlers(signal_state_t *state, PyObject *mod_dict)
{
    // Get signal handlers
    for (int signum = 1; signum < Py_NSIG; signum++) {
        void (*c_handler)(int) = PyOS_getsig(signum);
        PyObject *func;
        if (c_handler == SIG_DFL) {
            func = state->default_handler;
        }
        else if (c_handler == SIG_IGN) {
            func = state->ignore_handler;
        }
        else {
            func = Py_None; // None of our business
        }
        // If signal_module_exec() is called more than one, we must
        // clear the strong reference to the previous function.
        PyObject* old_func = get_handler(signum);
        set_handler(signum, Py_NewRef(func));
        Py_XDECREF(old_func);
    }

    // Install Python SIGINT handler which raises KeyboardInterrupt
    PyObject* sigint_func = get_handler(SIGINT);
    if (sigint_func == state->default_handler) {
        PyObject *int_handler = PyMapping_GetItemString(mod_dict,
                                                        "default_int_handler");
        if (!int_handler) {
            return -1;
        }

        set_handler(SIGINT, int_handler);
        Py_DECREF(sigint_func);
        PyOS_setsig(SIGINT, signal_handler);
    }
    return 0;
}


static int
signal_module_exec(PyObject *m)
{
    assert(!PyErr_Occurred());

    signal_state_t *state = &signal_global_state;
    _signal_module_state *modstate = get_signal_state(m);

    modstate->default_handler = state->default_handler;  // borrowed ref
    modstate->ignore_handler = state->ignore_handler;  // borrowed ref

#ifdef PYHAVE_ITIMER_ERROR
    modstate->itimer_error = PyErr_NewException("signal.itimer_error",
                                                PyExc_OSError, NULL);
    if (modstate->itimer_error == NULL) {
        return -1;
    }
#endif

    if (signal_add_constants(m) < 0) {
        return -1;
    }

    /* Add some symbolic constants to the module */
    PyObject *d = PyModule_GetDict(m);
    if (PyDict_SetItemString(d, "SIG_DFL", state->default_handler) < 0) {
        return -1;
    }
    if (PyDict_SetItemString(d, "SIG_IGN", state->ignore_handler) < 0) {
        return -1;
    }
#ifdef PYHAVE_ITIMER_ERROR
    if (PyDict_SetItemString(d, "ItimerError", modstate->itimer_error) < 0) {
        return -1;
    }
#endif

#if defined(HAVE_SIGWAITINFO) || defined(HAVE_SIGTIMEDWAIT)
    modstate->siginfo_type = PyStructSequence_NewType(&struct_siginfo_desc);
    if (modstate->siginfo_type == NULL) {
        return -1;
    }
#endif
#if defined(HAVE_SIGWAITINFO) || defined(HAVE_SIGTIMEDWAIT)
    if (PyModule_AddType(m, modstate->siginfo_type) < 0) {
        return -1;
    }
#endif

    PyThreadState *tstate = _PyThreadState_GET();
    if (_Py_IsMainInterpreter(tstate->interp)) {
        if (signal_get_set_handlers(state, d) < 0) {
            return -1;
        }
    }

    assert(!PyErr_Occurred());
    return 0;
}


#ifdef PYHAVE_ITIMER_ERROR
static int
_signal_module_traverse(PyObject *module, visitproc visit, void *arg)
{
    _signal_module_state *state = get_signal_state(module);
    Py_VISIT(state->itimer_error);
    Py_VISIT(state->siginfo_type);
    return 0;
}

static int
_signal_module_clear(PyObject *module)
{
    _signal_module_state *state = get_signal_state(module);
    Py_CLEAR(state->itimer_error);
    Py_CLEAR(state->siginfo_type);
    return 0;
}

static void
_signal_module_free(void *module)
{
    _signal_module_clear((PyObject *)module);
}
#endif  // PYHAVE_ITIMER_ERROR


static PyModuleDef_Slot signal_slots[] = {
    {Py_mod_exec, signal_module_exec},
    {0, NULL}
};

static struct PyModuleDef signal_module = {
    PyModuleDef_HEAD_INIT,
    "_signal",
    .m_doc = module_doc,
    .m_size = sizeof(_signal_module_state),
    .m_methods = signal_methods,
    .m_slots = signal_slots,
#ifdef PYHAVE_ITIMER_ERROR
    .m_traverse = _signal_module_traverse,
    .m_clear = _signal_module_clear,
    .m_free = _signal_module_free,
#endif
};


PyMODINIT_FUNC
PyInit__signal(void)
{
    return PyModuleDef_Init(&signal_module);
}


void
_PySignal_Fini(void)
{
    signal_state_t *state = &signal_global_state;

    // Restore default signals and clear handlers
    for (int signum = 1; signum < Py_NSIG; signum++) {
        PyObject *func = get_handler(signum);
        _Py_atomic_store_relaxed(&Handlers[signum].tripped, 0);
        set_handler(signum, NULL);
        if (func != NULL
            && func != Py_None
            && !compare_handler(func, state->default_handler)
            && !compare_handler(func, state->ignore_handler))
        {
            PyOS_setsig(signum, SIG_DFL);
        }
        Py_XDECREF(func);
    }

#ifdef MS_WINDOWS
    if (state->sigint_event != NULL) {
        CloseHandle(state->sigint_event);
        state->sigint_event = NULL;
    }
#endif

    Py_CLEAR(state->default_handler);
    Py_CLEAR(state->ignore_handler);
}


/* Declared in pyerrors.h */
int
PyErr_CheckSignals(void)
{
    PyThreadState *tstate = _PyThreadState_GET();
    if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
        return 0;
    }

    return _PyErr_CheckSignalsTstate(tstate);
}


/* Declared in cpython/pyerrors.h */
int
_PyErr_CheckSignalsTstate(PyThreadState *tstate)
{
    _Py_CHECK_EMSCRIPTEN_SIGNALS();
    if (!_Py_atomic_load(&is_tripped)) {
        return 0;
    }

    /*
     * The is_tripped variable is meant to speed up the calls to
     * PyErr_CheckSignals (both directly or via pending calls) when no
     * signal has arrived. This variable is set to 1 when a signal arrives
     * and it is set to 0 here, when we know some signals arrived. This way
     * we can run the registered handlers with no signals blocked.
     *
     * NOTE: with this approach we can have a situation where is_tripped is
     *       1 but we have no more signals to handle (Handlers[i].tripped
     *       is 0 for every signal i). This won't do us any harm (except
     *       we're gonna spent some cycles for nothing). This happens when
     *       we receive a signal i after we zero is_tripped and before we
     *       check Handlers[i].tripped.
     */
    _Py_atomic_store(&is_tripped, 0);

    _PyInterpreterFrame *frame = tstate->cframe->current_frame;
    while (frame && _PyFrame_IsIncomplete(frame)) {
        frame = frame->previous;
    }
    signal_state_t *state = &signal_global_state;
    for (int i = 1; i < Py_NSIG; i++) {
        if (!_Py_atomic_load_relaxed(&Handlers[i].tripped)) {
            continue;
        }
        _Py_atomic_store_relaxed(&Handlers[i].tripped, 0);

        /* Signal handlers can be modified while a signal is received,
         * and therefore the fact that trip_signal() or PyErr_SetInterrupt()
         * was called doesn't guarantee that there is still a Python
         * signal handler for it by the time PyErr_CheckSignals() is called
         * (see bpo-43406).
         */
        PyObject *func = get_handler(i);
        if (func == NULL || func == Py_None ||
            compare_handler(func, state->ignore_handler) ||
            compare_handler(func, state->default_handler)) {
            /* No Python signal handler due to aforementioned race condition.
             * We can't call raise() as it would break the assumption
             * that PyErr_SetInterrupt() only *simulates* an incoming
             * signal (i.e. it will never kill the process).
             * We also don't want to interrupt user code with a cryptic
             * asynchronous exception, so instead just write out an
             * unraisable error.
             */
            PyErr_Format(PyExc_OSError,
                         "Signal %i ignored due to race condition",
                         i);
            PyErr_WriteUnraisable(Py_None);
            continue;
        }
        PyObject *arglist = NULL;
        if (frame == NULL) {
            arglist = Py_BuildValue("(iO)", i, Py_None);
        }
        else {
            PyFrameObject *f = _PyFrame_GetFrameObject(frame);
            if (f != NULL) {
                arglist = Py_BuildValue("(iO)", i, f);
            }
        }
        PyObject *result;
        if (arglist) {
            result = _PyObject_Call(tstate, func, arglist, NULL);
            Py_DECREF(arglist);
        }
        else {
            result = NULL;
        }
        if (!result) {
            /* On error, re-schedule a call to _PyErr_CheckSignalsTstate() */
            _Py_atomic_store(&is_tripped, 1);
            return -1;
        }

        Py_DECREF(result);
    }

    return 0;
}



int
_PyErr_CheckSignals(void)
{
    PyThreadState *tstate = _PyThreadState_GET();
    return _PyErr_CheckSignalsTstate(tstate);
}


/* Simulate the effect of a signal arriving. The next time PyErr_CheckSignals
   is called,  the corresponding Python signal handler will be raised.

   Missing signal handler for the given signal number is silently ignored. */
int
PyErr_SetInterruptEx(int signum)
{
    if (signum < 1 || signum >= Py_NSIG) {
        return -1;
    }

    signal_state_t *state = &signal_global_state;
    PyObject *func = get_handler(signum);
    if (!compare_handler(func, state->ignore_handler)
            && !compare_handler(func, state->default_handler)) {
        trip_signal(signum);
    }
    return 0;
}

void
PyErr_SetInterrupt(void)
{
    (void) PyErr_SetInterruptEx(SIGINT);
}

static int
signal_install_handlers(void)
{
#ifdef SIGPIPE
    PyOS_setsig(SIGPIPE, SIG_IGN);
#endif
#ifdef SIGXFZ
    PyOS_setsig(SIGXFZ, SIG_IGN);
#endif
#ifdef SIGXFSZ
    PyOS_setsig(SIGXFSZ, SIG_IGN);
#endif

    // Import _signal to install the Python SIGINT handler
    PyObject *module = PyImport_ImportModule("_signal");
    if (!module) {
        return -1;
    }
    Py_DECREF(module);

    return 0;
}


/* Restore signals that the interpreter has called SIG_IGN on to SIG_DFL.
 *
 * All of the code in this function must only use async-signal-safe functions,
 * listed at `man 7 signal` or
 * http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html.
 *
 * If this function is updated, update also _posix_spawn() of subprocess.py.
 */
void
_Py_RestoreSignals(void)
{
#ifdef SIGPIPE
    PyOS_setsig(SIGPIPE, SIG_DFL);
#endif
#ifdef SIGXFZ
    PyOS_setsig(SIGXFZ, SIG_DFL);
#endif
#ifdef SIGXFSZ
    PyOS_setsig(SIGXFSZ, SIG_DFL);
#endif
}


int
_PySignal_Init(int install_signal_handlers)
{
    signal_state_t *state = &signal_global_state;

    state->default_handler = PyLong_FromVoidPtr((void *)SIG_DFL);
    if (state->default_handler == NULL) {
        return -1;
    }

    state->ignore_handler = PyLong_FromVoidPtr((void *)SIG_IGN);
    if (state->ignore_handler == NULL) {
        return -1;
    }

#ifdef MS_WINDOWS
    /* Create manual-reset event, initially unset */
    state->sigint_event = CreateEvent(NULL, TRUE, FALSE, FALSE);
    if (state->sigint_event == NULL) {
        PyErr_SetFromWindowsErr(0);
        return -1;
    }
#endif

    for (int signum = 1; signum < Py_NSIG; signum++) {
        _Py_atomic_store_relaxed(&Handlers[signum].tripped, 0);
    }

    if (install_signal_handlers) {
        if (signal_install_handlers() < 0) {
            return -1;
        }
    }

    return 0;
}


// The caller doesn't have to hold the GIL
int
_PyOS_InterruptOccurred(PyThreadState *tstate)
{
    _Py_EnsureTstateNotNULL(tstate);
    if (!_Py_ThreadCanHandleSignals(tstate->interp)) {
        return 0;
    }

    if (!_Py_atomic_load_relaxed(&Handlers[SIGINT].tripped)) {
        return 0;
    }

    _Py_atomic_store_relaxed(&Handlers[SIGINT].tripped, 0);
    return 1;
}


// The caller must to hold the GIL
int
PyOS_InterruptOccurred(void)
{
    PyThreadState *tstate = _PyThreadState_GET();
    return _PyOS_InterruptOccurred(tstate);
}


#ifdef HAVE_FORK
static void
_clear_pending_signals(void)
{
    if (!_Py_atomic_load(&is_tripped)) {
        return;
    }

    _Py_atomic_store(&is_tripped, 0);
    for (int i = 1; i < Py_NSIG; ++i) {
        _Py_atomic_store_relaxed(&Handlers[i].tripped, 0);
    }
}

void
_PySignal_AfterFork(void)
{
    /* Clear the signal flags after forking so that they aren't handled
     * in both processes if they came in just before the fork() but before
     * the interpreter had an opportunity to call the handlers.  issue9535. */
    _clear_pending_signals();
}
#endif   /* HAVE_FORK */


int
_PyOS_IsMainThread(void)
{
    PyInterpreterState *interp = _PyInterpreterState_GET();
    return _Py_ThreadCanHandleSignals(interp);
}

#ifdef MS_WINDOWS
/* Returns a manual-reset event which gets tripped whenever
   SIGINT is received.

   Python.h does not include windows.h so we do cannot use HANDLE
   as the return type of this function.  We use void* instead. */
void *_PyOS_SigintEvent(void)
{
    signal_state_t *state = &signal_global_state;
    return state->sigint_event;
}
#endif