summaryrefslogtreecommitdiff
path: root/src/fdevent.c
blob: bd19ec68147b795d1e307bb8b93969de8e0563c2 (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
#include "first.h"

#include "fdevent_impl.h"
#include "fdevent.h"
#include "base.h"
#include "buffer.h"
#include "log.h"

#include <sys/types.h>
#include <sys/wait.h>
#include "sys-socket.h"

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <time.h>

#ifdef SOCK_CLOEXEC
static int use_sock_cloexec;
#endif
#ifdef SOCK_NONBLOCK
static int use_sock_nonblock;
#endif

int fdevent_config(server *srv) {
	static const struct ev_map { fdevent_handler_t et; const char *name; } event_handlers[] =
	{
		/* - epoll is most reliable
		 * - select works everywhere
		 */
#ifdef FDEVENT_USE_LINUX_EPOLL
		{ FDEVENT_HANDLER_LINUX_SYSEPOLL, "linux-sysepoll" },
		{ FDEVENT_HANDLER_LINUX_SYSEPOLL, "epoll" },
#endif
#ifdef FDEVENT_USE_SOLARIS_PORT
		{ FDEVENT_HANDLER_SOLARIS_PORT,   "solaris-eventports" },
#endif
#ifdef FDEVENT_USE_SOLARIS_DEVPOLL
		{ FDEVENT_HANDLER_SOLARIS_DEVPOLL,"solaris-devpoll" },
#endif
#ifdef FDEVENT_USE_FREEBSD_KQUEUE
		{ FDEVENT_HANDLER_FREEBSD_KQUEUE, "freebsd-kqueue" },
		{ FDEVENT_HANDLER_FREEBSD_KQUEUE, "kqueue" },
#endif
#ifdef FDEVENT_USE_POLL
		{ FDEVENT_HANDLER_POLL,           "poll" },
#endif
#ifdef FDEVENT_USE_SELECT
		{ FDEVENT_HANDLER_SELECT,         "select" },
#endif
#ifdef FDEVENT_USE_LIBEV
		{ FDEVENT_HANDLER_LIBEV,          "libev" },
#endif
		{ FDEVENT_HANDLER_UNSET,          NULL }
	};

	if (buffer_string_is_empty(srv->srvconf.event_handler)) {
		/* choose a good default
		 *
		 * the event_handler list is sorted by 'goodness'
		 * taking the first available should be the best solution
		 */
		srv->event_handler = event_handlers[0].et;

		if (FDEVENT_HANDLER_UNSET == srv->event_handler) {
			log_error_write(srv, __FILE__, __LINE__, "s",
					"sorry, there is no event handler for this system");

			return -1;
		}

		buffer_copy_string(srv->srvconf.event_handler, event_handlers[0].name);
	} else {
		/*
		 * User override
		 */

		for (size_t i = 0; event_handlers[i].name; i++) {
			if (0 == strcmp(event_handlers[i].name, srv->srvconf.event_handler->ptr)) {
				srv->event_handler = event_handlers[i].et;
				break;
			}
		}

		if (FDEVENT_HANDLER_UNSET == srv->event_handler) {
			log_error_write(srv, __FILE__, __LINE__, "sb",
					"the selected event-handler in unknown or not supported:",
					srv->srvconf.event_handler );

			return -1;
		}
	}

      #ifdef FDEVENT_USE_SELECT
	if (srv->event_handler == FDEVENT_HANDLER_SELECT) {
		/* select limits itself
		 *
		 * as it is a hard limit and will lead to a segfault we add some safety
		 * */
		srv->max_fds = FD_SETSIZE - 200;
	}
	else
      #endif
	{
		srv->max_fds = 4096;
	}

	return 0;
}

const char * fdevent_show_event_handlers(void) {
    return
      "\nEvent Handlers:\n\n"
#ifdef FDEVENT_USE_SELECT
      "\t+ select (generic)\n"
#else
      "\t- select (generic)\n"
#endif
#ifdef FDEVENT_USE_POLL
      "\t+ poll (Unix)\n"
#else
      "\t- poll (Unix)\n"
#endif
#ifdef FDEVENT_USE_LINUX_EPOLL
      "\t+ epoll (Linux)\n"
#else
      "\t- epoll (Linux)\n"
#endif
#ifdef FDEVENT_USE_SOLARIS_DEVPOLL
      "\t+ /dev/poll (Solaris)\n"
#else
      "\t- /dev/poll (Solaris)\n"
#endif
#ifdef FDEVENT_USE_SOLARIS_PORT
      "\t+ eventports (Solaris)\n"
#else
      "\t- eventports (Solaris)\n"
#endif
#ifdef FDEVENT_USE_FREEBSD_KQUEUE
      "\t+ kqueue (FreeBSD)\n"
#else
      "\t- kqueue (FreeBSD)\n"
#endif
#ifdef FDEVENT_USE_LIBEV
      "\t+ libev (generic)\n"
#else
      "\t- libev (generic)\n"
#endif
      ;
}

fdevents *fdevent_init(server *srv) {
	fdevents *ev;
	int type = srv->event_handler;
	size_t maxfds;

      #ifdef SOCK_CLOEXEC
	/* Test if SOCK_CLOEXEC is supported by kernel.
	 * Linux kernels < 2.6.27 might return EINVAL if SOCK_CLOEXEC used
	 * https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=529929
	 * http://www.linksysinfo.org/index.php?threads/lighttpd-no-longer-starts-toastman-1-28-0510-7.73132/
	 * Test if SOCK_NONBLOCK is ignored by kernel on sockets.
	 * (reported on Android running a custom ROM)
	 * https://redmine.lighttpd.net/issues/2883
	 */
       #ifdef SOCK_NONBLOCK
	int fd = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
       #else
	int fd = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, 0);
       #endif
	if (fd >= 0) {
		int flags = fcntl(fd, F_GETFL, 0);
              #ifdef SOCK_NONBLOCK
		use_sock_nonblock = (-1 != flags && (flags & O_NONBLOCK));
              #endif
		use_sock_cloexec = 1;
		close(fd);
	}
      #endif

      #ifdef FDEVENT_USE_SELECT
	if (type == FDEVENT_HANDLER_SELECT) {
		if (srv->max_fds > (int)FD_SETSIZE - 200) {
			srv->max_fds = (int)FD_SETSIZE - 200;
		}
	}
      #endif
	maxfds = srv->max_fds + 1; /*(+1 for event-handler fd)*/

	ev = calloc(1, sizeof(*ev));
	force_assert(NULL != ev);
	ev->srv = srv;
	ev->fdarray = calloc(maxfds, sizeof(*ev->fdarray));
	if (NULL == ev->fdarray) {
		log_error_write(srv, __FILE__, __LINE__, "SDS",
				"server.max-fds too large? (", maxfds-1, ")");
		free(ev);
		return NULL;
	}
	ev->maxfds = maxfds;

	switch(type) {
	#ifdef FDEVENT_USE_POLL
	case FDEVENT_HANDLER_POLL:
		if (0 == fdevent_poll_init(ev)) return ev;
		break;
	#endif
	#ifdef FDEVENT_USE_SELECT
	case FDEVENT_HANDLER_SELECT:
		if (0 == fdevent_select_init(ev)) return ev;
		break;
	#endif
	#ifdef FDEVENT_USE_LINUX_EPOLL
	case FDEVENT_HANDLER_LINUX_SYSEPOLL:
		if (0 == fdevent_linux_sysepoll_init(ev)) return ev;
		break;
	#endif
	#ifdef FDEVENT_USE_SOLARIS_DEVPOLL
	case FDEVENT_HANDLER_SOLARIS_DEVPOLL:
		if (0 == fdevent_solaris_devpoll_init(ev)) return ev;
		break;
	#endif
	#ifdef FDEVENT_USE_SOLARIS_PORT
	case FDEVENT_HANDLER_SOLARIS_PORT:
		if (0 == fdevent_solaris_port_init(ev)) return ev;
		break;
	#endif
	#ifdef FDEVENT_USE_FREEBSD_KQUEUE
	case FDEVENT_HANDLER_FREEBSD_KQUEUE:
		if (0 == fdevent_freebsd_kqueue_init(ev)) return ev;
		break;
	#endif
	#ifdef FDEVENT_USE_LIBEV
	case FDEVENT_HANDLER_LIBEV:
		if (0 == fdevent_libev_init(ev)) return ev;
		break;
	#endif
	case FDEVENT_HANDLER_UNSET:
	default:
		break;
	}

	free(ev->fdarray);
	free(ev);

	log_error_write(srv, __FILE__, __LINE__, "sBS",
		"event-handler failed:", srv->srvconf.event_handler, "; try to set server.event-handler = \"poll\" or \"select\"");
	return NULL;
}

void fdevent_free(fdevents *ev) {
	size_t i;
	if (!ev) return;

	if (ev->free) ev->free(ev);

	for (i = 0; i < ev->maxfds; i++) {
		/* (fdevent_sched_run() should already have been run,
		 *  but take reasonable precautions anyway) */
		if (ev->fdarray[i])
			free((fdnode *)((uintptr_t)ev->fdarray[i] & ~0x3));
	}

	free(ev->fdarray);
	free(ev);
}

int fdevent_reset(fdevents *ev) {
	int rc = (NULL != ev->reset) ? ev->reset(ev) : 0;
	if (-1 == rc) {
		log_error_write(ev->srv, __FILE__, __LINE__, "sBS",
			"event-handler failed:", ev->srv->srvconf.event_handler, "; try to set server.event-handler = \"poll\" or \"select\"");
	}
	return rc;
}

static fdnode *fdnode_init(void) {
	return calloc(1, sizeof(fdnode));
}

static void fdnode_free(fdnode *fdn) {
	free(fdn);
}

fdnode * fdevent_register(fdevents *ev, int fd, fdevent_handler handler, void *ctx) {
	fdnode *fdn  = ev->fdarray[fd] = fdnode_init();
	force_assert(NULL != fdn);
	fdn->handler = handler;
	fdn->fd      = fd;
	fdn->ctx     = ctx;
	fdn->events  = 0;
	fdn->fde_ndx = -1;
      #ifdef FDEVENT_USE_LIBEV
	fdn->handler_ctx = NULL;
      #endif
	return fdn;
}

void fdevent_unregister(fdevents *ev, int fd) {
	fdnode *fdn = ev->fdarray[fd];
	if ((uintptr_t)fdn & 0x3) return; /*(should not happen)*/
	ev->fdarray[fd] = NULL;
	fdnode_free(fdn);
}

void fdevent_sched_close(fdevents *ev, int fd, int issock) {
	fdnode *fdn = ev->fdarray[fd];
	if ((uintptr_t)fdn & 0x3) return;
	ev->fdarray[fd] = (fdnode *)((uintptr_t)fdn | (issock ? 0x1 : 0x2));
	fdn->handler = (fdevent_handler)NULL;
	fdn->ctx = ev->pendclose;
	ev->pendclose = fdn;
}

static void fdevent_sched_run(fdevents *ev) {
	server *srv = ev->srv;
	for (fdnode *fdn = ev->pendclose; fdn; ) {
		int fd, rc;
		fdnode *fdn_tmp;
	      #ifdef _WIN32
		rc = (uintptr_t)fdn & 0x3;
	      #endif
		fdn = (fdnode *)((uintptr_t)fdn & ~0x3);
		fd = fdn->fd;
	      #ifdef _WIN32
		if (rc == 0x1) {
			rc = closesocket(fd);
		}
		else if (rc == 0x2) {
			rc = close(fd);
		}
	      #else
		rc = close(fd);
	      #endif

		if (0 != rc) {
			log_error_write(srv, __FILE__, __LINE__, "sds", "close failed ", fd, strerror(errno));
		}
		else {
			--srv->cur_fds;
		}

		fdn_tmp = fdn;
		fdn = (fdnode *)fdn->ctx; /* next */
		/*(fdevent_unregister)*/
		fdnode_free(fdn_tmp);
		ev->fdarray[fd] = NULL;
	}
	ev->pendclose = NULL;
}

static void fdevent_fdnode_event_unsetter(fdevents *ev, fdnode *fdn) {
    if (-1 == fdn->fde_ndx) return;
    if (0 == ev->event_del(ev, fdn)) {
        fdn->fde_ndx = -1;
        fdn->events = 0;
    }
    else {
        log_error_write(ev->srv, __FILE__, __LINE__, "SS",
                        "fdevent event_del failed: ", strerror(errno));
    }
}

static void fdevent_fdnode_event_setter(fdevents *ev, fdnode *fdn, int events) {
    /*(Note: skips registering with kernel if initial events is 0,
     * so caller should pass non-zero events for initial registration.
     * If never registered due to never being called with non-zero events,
     * then FDEVENT_HUP or FDEVENT_ERR will never be returned.) */
    if (fdn->events == events) return;/*(no change; nothing to do)*/

    if (0 == ev->event_set(ev, fdn, events))
        fdn->events = events;
    else
        log_error_write(ev->srv, __FILE__, __LINE__, "SS",
                        "fdevent event_set failed: ", strerror(errno));
}

void fdevent_fdnode_event_del(fdevents *ev, fdnode *fdn) {
    if (NULL != fdn) fdevent_fdnode_event_unsetter(ev, fdn);
}

void fdevent_fdnode_event_set(fdevents *ev, fdnode *fdn, int events) {
    if (NULL != fdn) fdevent_fdnode_event_setter(ev, fdn, events);
}

void fdevent_fdnode_event_add(fdevents *ev, fdnode *fdn, int event) {
    if (NULL != fdn) fdevent_fdnode_event_setter(ev, fdn, (fdn->events|event));
}

void fdevent_fdnode_event_clr(fdevents *ev, fdnode *fdn, int event) {
    if (NULL != fdn) fdevent_fdnode_event_setter(ev, fdn, (fdn->events&~event));
}

int fdevent_poll(fdevents *ev, int timeout_ms) {
    int n = ev->poll(ev, timeout_ms);
    if (n >= 0)
        fdevent_sched_run(ev);
    else if (errno != EINTR)
        log_error_write(ev->srv, __FILE__, __LINE__, "SS",
                        "fdevent_poll failed: ", strerror(errno));
    return n;
}

void fdevent_setfd_cloexec(int fd) {
#ifdef FD_CLOEXEC
	if (fd < 0) return;
	force_assert(-1 != fcntl(fd, F_SETFD, FD_CLOEXEC));
#else
	UNUSED(fd);
#endif
}

void fdevent_clrfd_cloexec(int fd) {
#ifdef FD_CLOEXEC
	if (fd >= 0) force_assert(-1 != fcntl(fd, F_SETFD, 0));
#else
	UNUSED(fd);
#endif
}

int fdevent_fcntl_set_nb(fdevents *ev, int fd) {
	UNUSED(ev);
#ifdef O_NONBLOCK
	return fcntl(fd, F_SETFL, O_NONBLOCK | O_RDWR);
#else
	UNUSED(fd);
	return 0;
#endif
}

int fdevent_fcntl_set_nb_cloexec(fdevents *ev, int fd) {
	fdevent_setfd_cloexec(fd);
	return fdevent_fcntl_set_nb(ev, fd);
}

int fdevent_fcntl_set_nb_cloexec_sock(fdevents *ev, int fd) {
#if defined(SOCK_CLOEXEC) && defined(SOCK_NONBLOCK)
	if (use_sock_cloexec && use_sock_nonblock)
		return 0;
#endif
	return fdevent_fcntl_set_nb_cloexec(ev, fd);
}

int fdevent_socket_cloexec(int domain, int type, int protocol) {
	int fd;
#ifdef SOCK_CLOEXEC
	if (use_sock_cloexec)
		return socket(domain, type | SOCK_CLOEXEC, protocol);
#endif
	if (-1 != (fd = socket(domain, type, protocol))) {
#ifdef FD_CLOEXEC
		force_assert(-1 != fcntl(fd, F_SETFD, FD_CLOEXEC));
#endif
	}
	return fd;
}

int fdevent_socket_nb_cloexec(int domain, int type, int protocol) {
	int fd;
#ifdef SOCK_CLOEXEC
       #ifdef SOCK_NONBLOCK
	if (use_sock_cloexec && use_sock_nonblock)
		return socket(domain, type | SOCK_CLOEXEC | SOCK_NONBLOCK, protocol);
       #else
	if (use_sock_cloexec) {
		fd = socket(domain, type | SOCK_CLOEXEC, protocol);
	      #ifdef O_NONBLOCK
		if (-1 != fd) force_assert(-1 != fcntl(fd,F_SETFL,O_NONBLOCK|O_RDWR));
	      #endif
		return fd;
	}
       #endif
#endif
	if (-1 != (fd = socket(domain, type, protocol))) {
#ifdef FD_CLOEXEC
		force_assert(-1 != fcntl(fd, F_SETFD, FD_CLOEXEC));
#endif
#ifdef O_NONBLOCK
		force_assert(-1 != fcntl(fd, F_SETFL, O_NONBLOCK | O_RDWR));
#endif
	}
	return fd;
}

#ifndef O_BINARY
#define O_BINARY 0
#endif
#ifndef O_LARGEFILE
#define O_LARGEFILE 0
#endif
#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif
#ifndef O_NOFOLLOW
#define O_NOFOLLOW 0
#endif

/*(O_NOFOLLOW is not handled here)*/
/*(Note: O_NOFOLLOW affects only the final path segment, the target file,
 * not any intermediate symlinks along the path)*/

/* O_CLOEXEC handled further below, if defined) */
#ifdef O_NONBLOCK
#define FDEVENT_O_FLAGS \
        (O_BINARY | O_LARGEFILE | O_NOCTTY | O_NONBLOCK)
#else
#define FDEVENT_O_FLAGS \
        (O_BINARY | O_LARGEFILE | O_NOCTTY )
#endif

int fdevent_open_cloexec(const char *pathname, int symlinks, int flags, mode_t mode) {
	if (!symlinks) flags |= O_NOFOLLOW;
#ifdef O_CLOEXEC
	return open(pathname, flags | O_CLOEXEC | FDEVENT_O_FLAGS, mode);
#else
	int fd = open(pathname, flags | FDEVENT_O_FLAGS, mode);
#ifdef FD_CLOEXEC
	if (fd != -1)
		force_assert(-1 != fcntl(fd, F_SETFD, FD_CLOEXEC));
#endif
	return fd;
#endif
}


int fdevent_open_devnull(void) {
  #if defined(_WIN32)
    return fdevent_open_cloexec("nul", 0, O_RDWR, 0);
  #else
    return fdevent_open_cloexec("/dev/null", 0, O_RDWR, 0);
  #endif
}


int fdevent_open_dirname(char *path, int symlinks) {
    /*(handle special cases of no dirname or dirname is root directory)*/
    char * const c = strrchr(path, '/');
    const char * const dname = (NULL != c ? c == path ? "/" : path : ".");
    int dfd;
    int flags = O_RDONLY;
  #ifdef O_DIRECTORY
    flags |= O_DIRECTORY;
  #endif
    if (NULL != c) *c = '\0';
    dfd = fdevent_open_cloexec(dname, symlinks, flags, 0);
    if (NULL != c) *c = '/';
    return dfd;
}


int fdevent_accept_listenfd(int listenfd, struct sockaddr *addr, size_t *addrlen) {
	int fd;
	socklen_t len = (socklen_t) *addrlen;

      #if defined(SOCK_CLOEXEC) && defined(SOCK_NONBLOCK)
       #if defined(__NetBSD__)
	const int sock_cloexec = 1;
	fd = paccept(listenfd, addr, &len, NULL, SOCK_CLOEXEC | SOCK_NONBLOCK);
       #else
	int sock_cloexec = use_sock_cloexec;
	if (sock_cloexec) {
		fd = accept4(listenfd, addr, &len, SOCK_CLOEXEC | SOCK_NONBLOCK);
		if (fd >= 0) {
			if (!use_sock_nonblock) {
				if (0 != fdevent_fcntl_set_nb(NULL, fd)) {
					close(fd);
					fd = -1;
				}
			}
		} else if (errno == ENOSYS || errno == ENOTSUP) {
			fd = accept(listenfd, addr, &len);
			sock_cloexec = 0;
		}
	}
	else {
		fd = accept(listenfd, addr, &len);
	}
       #endif
      #else
	const int sock_cloexec = 0;
	fd = accept(listenfd, addr, &len);
      #endif

	if (fd >= 0) {
		*addrlen = (size_t)len;
		if (!sock_cloexec && 0 != fdevent_fcntl_set_nb_cloexec(NULL, fd)) {
			close(fd);
			fd = -1;
		}
	}
	return fd;
}


#ifdef __APPLE__
#include <crt_externs.h>
#define environ (* _NSGetEnviron())
#else
extern char **environ;
#endif
char ** fdevent_environ (void) { return environ; }


#ifdef FD_CLOEXEC
static int fdevent_dup2_close_clrfd_cloexec(int oldfd, int newfd) {
    if (oldfd >= 0) {
        if (oldfd != newfd) {
            force_assert(oldfd > STDERR_FILENO);
            if (newfd != dup2(oldfd, newfd)) return -1;
        }
        else {
            fdevent_clrfd_cloexec(newfd);
        }
    }
    return newfd;
}
#else
static int fdevent_dup2_close_clrfd_cloexec(int oldfd, int newfd, int reuse) {
    if (oldfd >= 0) {
        if (oldfd != newfd) {
            force_assert(oldfd > STDERR_FILENO);
            if (newfd != dup2(oldfd, newfd)) return -1;
            if (!reuse) close(oldfd);
        }
    }
    return newfd;
}
#endif


int fdevent_set_stdin_stdout_stderr(int fdin, int fdout, int fderr) {
  #ifdef FD_CLOEXEC
    if (STDIN_FILENO != fdevent_dup2_close_clrfd_cloexec(fdin, STDIN_FILENO))
        return -1;
    if (STDOUT_FILENO != fdevent_dup2_close_clrfd_cloexec(fdout, STDOUT_FILENO))
        return -1;
    if (STDERR_FILENO != fdevent_dup2_close_clrfd_cloexec(fderr, STDERR_FILENO))
        return -1;
  #else
    if (STDIN_FILENO != fdevent_dup2_close_clrfd_cloexec(fdin, STDIN_FILENO,
                                                         fdin == fdout
                                                         || fdin == fderr))
        return -1;
    if (STDOUT_FILENO != fdevent_dup2_close_clrfd_cloexec(fdout, STDOUT_FILENO,
                                                          fdout == fderr))
        return -1;
    if (STDERR_FILENO != fdevent_dup2_close_clrfd_cloexec(fderr, STDERR_FILENO,
                                                          0))
        return -1;
  #endif

    return 0;
}


#include <stdio.h>      /* perror() */
#include <signal.h>     /* signal() */

pid_t fdevent_fork_execve(const char *name, char *argv[], char *envp[], int fdin, int fdout, int fderr, int dfd) {
 #ifdef HAVE_FORK

    pid_t pid = fork();
    if (0 != pid) return pid; /* parent (pid > 0) or fork() error (-1 == pid) */

    /* child (0 == pid) */

    if (-1 != dfd) {
        if (0 != fchdir(dfd))
            _exit(errno);
        close(dfd);
    }

    if (0 != fdevent_set_stdin_stdout_stderr(fdin, fdout, fderr)) _exit(errno);
  #ifdef FD_CLOEXEC
    /*(might not be sufficient for open fds, but modern OS have FD_CLOEXEC)*/
    for (int i = 3; i < 256; ++i) close(i);
  #endif

    /* reset_signals which may have been ignored (SIG_IGN) */
  #ifdef SIGTTOU
    signal(SIGTTOU, SIG_DFL);
  #endif
  #ifdef SIGTTIN
    signal(SIGTTIN, SIG_DFL);
  #endif
  #ifdef SIGTSTP
    signal(SIGTSTP, SIG_DFL);
  #endif
    signal(SIGPIPE, SIG_DFL);

    execve(name, argv, envp ? envp : environ);

    if (0 == memcmp(argv[0], "/bin/sh", sizeof("/bin/sh")-1)
        && argv[1] && 0 == memcmp(argv[1], "-c", sizeof("-c")-1))
        perror(argv[2]);
    else
        perror(argv[0]);
    _exit(errno);

 #else

    UNUSED(name);
    UNUSED(argv);
    UNUSED(envp);
    UNUSED(fdin);
    UNUSED(fdout);
    UNUSED(fderr);
    UNUSED(dfd);
    return (pid_t)-1;

 #endif
}


typedef struct fdevent_cmd_pipe {
    pid_t pid;
    int fds[2];
    const char *cmd;
    time_t start;
} fdevent_cmd_pipe;

typedef struct fdevent_cmd_pipes {
    fdevent_cmd_pipe *ptr;
    size_t used;
    size_t size;
} fdevent_cmd_pipes;

static fdevent_cmd_pipes cmd_pipes;


static pid_t fdevent_open_logger_pipe_spawn(const char *logger, int rfd) {
    char *args[4];
    int devnull = fdevent_open_devnull();
    pid_t pid;

    if (-1 == devnull) {
        return -1;
    }

    *(const char **)&args[0] = "/bin/sh";
    *(const char **)&args[1] = "-c";
    *(const char **)&args[2] = logger;
    args[3] = NULL;

    pid = fdevent_fork_execve(args[0], args, NULL, rfd, devnull, devnull, -1);

    if (pid > 0) {
        close(devnull);
    }
    else {
        int errnum = errno;
        close(devnull);
        errno = errnum;
    }
    return pid;
}


static void fdevent_restart_logger_pipe(fdevent_cmd_pipe *fcp, time_t ts) {
    if (fcp->pid > 0) return;  /* assert */
    if (fcp->start + 5 < ts) { /* limit restart to once every 5 sec */
        /* restart child process using existing pipe fds */
        fcp->start = ts;
        fcp->pid = fdevent_open_logger_pipe_spawn(fcp->cmd, fcp->fds[0]);
    }
}


void fdevent_restart_logger_pipes(time_t ts) {
    for (size_t i = 0; i < cmd_pipes.used; ++i) {
        fdevent_cmd_pipe * const fcp = cmd_pipes.ptr+i;
        if (fcp->pid > 0) continue;
        fdevent_restart_logger_pipe(fcp, ts);
    }
}


int fdevent_waitpid_logger_pipe_pid(pid_t pid, time_t ts) {
    for (size_t i = 0; i < cmd_pipes.used; ++i) {
        fdevent_cmd_pipe * const fcp = cmd_pipes.ptr+i;
        if (pid != fcp->pid) continue;
        fcp->pid = -1;
        fdevent_restart_logger_pipe(fcp, ts);
        return 1;
    }
    return 0;
}


void fdevent_clr_logger_pipe_pids(void) {
    for (size_t i = 0; i < cmd_pipes.used; ++i) {
        fdevent_cmd_pipe *fcp = cmd_pipes.ptr+i;
        fcp->pid = -1;
    }
}


int fdevent_reaped_logger_pipe(pid_t pid) {
    for (size_t i = 0; i < cmd_pipes.used; ++i) {
        fdevent_cmd_pipe *fcp = cmd_pipes.ptr+i;
        if (fcp->pid == pid) {
            time_t ts = time(NULL);
            if (fcp->start + 5 < ts) { /* limit restart to once every 5 sec */
                fcp->start = ts;
                fcp->pid = fdevent_open_logger_pipe_spawn(fcp->cmd,fcp->fds[0]);
                return 1;
            }
            else {
                fcp->pid = -1;
                return -1;
            }
        }
    }
    return 0;
}


void fdevent_close_logger_pipes(void) {
    for (size_t i = 0; i < cmd_pipes.used; ++i) {
        fdevent_cmd_pipe *fcp = cmd_pipes.ptr+i;
        close(fcp->fds[0]);
        if (fcp->fds[1] != STDERR_FILENO) close(fcp->fds[1]);
    }
    free(cmd_pipes.ptr);
    cmd_pipes.ptr = NULL;
    cmd_pipes.used = 0;
    cmd_pipes.size = 0;
}


void fdevent_breakagelog_logger_pipe(int fd) {
    for (size_t i = 0; i < cmd_pipes.used; ++i) {
        fdevent_cmd_pipe *fcp = cmd_pipes.ptr+i;
        if (fcp->fds[1] != fd) continue;
        fcp->fds[1] = STDERR_FILENO;
        break;
    }
}


static void fdevent_init_logger_pipe(const char *cmd, int fds[2], pid_t pid) {
    fdevent_cmd_pipe *fcp;
    if (cmd_pipes.used == cmd_pipes.size) {
        cmd_pipes.size += 4;
        cmd_pipes.ptr =
          realloc(cmd_pipes.ptr, cmd_pipes.size * sizeof(fdevent_cmd_pipe));
        force_assert(cmd_pipes.ptr);
    }
    fcp = cmd_pipes.ptr + cmd_pipes.used++;
    fcp->cmd = cmd; /* note: cmd must persist in memory (or else copy here) */
    fcp->fds[0] = fds[0];
    fcp->fds[1] = fds[1];
    fcp->pid = pid;
    fcp->start = time(NULL);
}


static int fdevent_open_logger_pipe(const char *logger) {
    int fds[2];
    pid_t pid;
    if (pipe(fds)) {
        return -1;
    }
    fdevent_setfd_cloexec(fds[0]);
    fdevent_setfd_cloexec(fds[1]);
    /*(nonblocking write() from lighttpd)*/
    if (0 != fdevent_fcntl_set_nb(NULL, fds[1])) { /*(ignore)*/ }

    pid = fdevent_open_logger_pipe_spawn(logger, fds[0]);

    if (pid > 0) {
        fdevent_init_logger_pipe(logger, fds, pid);
        return fds[1];
    }
    else {
        int errnum = errno;
        close(fds[0]);
        close(fds[1]);
        errno = errnum;
        return -1;
    }
}


int fdevent_open_logger(const char *logger) {
    if (logger[0] != '|') { /*(permit symlinks)*/
        int flags = O_APPEND | O_WRONLY | O_CREAT;
        return fdevent_open_cloexec(logger, 1, flags, 0644);
    }
    else {
        return fdevent_open_logger_pipe(logger+1); /*(skip the '|')*/
    }
}

int fdevent_cycle_logger(const char *logger, int *curfd) {
    if (logger[0] != '|') {
        int fd = fdevent_open_logger(logger);
        if (-1 == fd) return -1; /*(error; leave *curfd as-is)*/
        if (-1 != *curfd) close(*curfd);
        *curfd = fd;
    }
    return *curfd;
}


#ifndef MSG_DONTWAIT
#define MSG_DONTWAIT 0
#endif
#ifndef MSG_NOSIGNAL
#define MSG_NOSIGNAL 0
#endif


ssize_t fdevent_socket_read_discard (int fd, char *buf, size_t sz, int family, int so_type) {
  #if defined(MSG_TRUNC) && defined(__linux__)
    if ((family == AF_INET || family == AF_INET6) && so_type == SOCK_STREAM) {
        ssize_t len = recv(fd, buf, sz, MSG_TRUNC|MSG_DONTWAIT|MSG_NOSIGNAL);
        if (len >= 0 || errno != EINVAL) return len;
    }
  #else
    UNUSED(family);
    UNUSED(so_type);
  #endif
    return read(fd, buf, sz);
}


#include <sys/ioctl.h>
#ifdef HAVE_SYS_FILIO_H
#include <sys/filio.h>  /* FIONREAD (for illumos (OpenIndiana)) */
#endif
#ifdef _WIN32
#include <winsock2.h>
#endif
int fdevent_ioctl_fionread (int fd, int fdfmt, int *toread) {
  #ifdef _WIN32
    if (fdfmt != S_IFSOCK) { errno = ENOTSOCK; return -1; }
    return ioctlsocket(fd, FIONREAD, toread);
  #else
   #ifdef __CYGWIN__
    /*(cygwin supports FIONREAD on pipes, not sockets)*/
    if (fdfmt != S_IFIFO) { errno = EOPNOTSUPP; return -1; }
   #else
    UNUSED(fdfmt);
   #endif
    return ioctl(fd, FIONREAD, toread);
  #endif
}


int fdevent_connect_status(int fd) {
    /* try to finish the connect() */
    /*(should be called after connect() only when fd is writable (POLLOUT))*/
    int opt;
    socklen_t len = sizeof(opt);
    return (0 == getsockopt(fd,SOL_SOCKET,SO_ERROR,&opt,&len)) ? opt : errno;
}


#include <netinet/tcp.h>
#if (defined(__APPLE__) && defined(__MACH__)) \
  || defined(__FreeBSD__) || defined(__NetBSD__) \
  || defined(__OpenBSD__) || defined(__DragonFly__)
#include <netinet/tcp_fsm.h>
#endif

/* fd must be TCP socket (AF_INET, AF_INET6), end-of-stream recv() 0 bytes */
int fdevent_is_tcp_half_closed(int fd) {
  #ifdef TCP_CONNECTION_INFO     /* Darwin */
    struct tcp_connection_info tcpi;
    socklen_t tlen = sizeof(tcpi);
    return (0 == getsockopt(fd, IPPROTO_TCP, TCP_CONNECTION_INFO, &tcpi, &tlen)
            && tcpi.tcpi_state == TCPS_CLOSE_WAIT);
  #elif defined(TCP_INFO) && defined(TCPS_CLOSE_WAIT)
    /* FreeBSD, NetBSD (not present in OpenBSD or DragonFlyBSD) */
    struct tcp_info tcpi;
    socklen_t tlen = sizeof(tcpi);
    return (0 == getsockopt(fd, IPPROTO_TCP, TCP_INFO, &tcpi, &tlen)
            && tcpi.tcpi_state == TCPS_CLOSE_WAIT);
  #elif defined(TCP_INFO) && defined(__linux__)
    /* Linux (TCP_CLOSE_WAIT is enum, so can not #ifdef TCP_CLOSE_WAIT) */
    struct tcp_info tcpi;
    socklen_t tlen = sizeof(tcpi);/*SOL_TCP == IPPROTO_TCP*/
    return (0 == getsockopt(fd,     SOL_TCP, TCP_INFO, &tcpi, &tlen)
            && tcpi.tcpi_state == TCP_CLOSE_WAIT);
  #else
    UNUSED(fd);
    /*(0 != getpeername() error might indicate TCP RST, but success
     * would not differentiate between half-close and full-close)*/
    return 0; /* false (not half-closed) or TCP state unknown */
  #endif
}


int fdevent_set_tcp_nodelay (const int fd, const int opt)
{
    return setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &opt, sizeof(opt));
}


int fdevent_set_so_reuseaddr (const int fd, const int opt)
{
    return setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
}