src/third_party/libevent/kqueue.c - cobalt - Git at Google

 /*	$OpenBSD: kqueue.c,v 1.5 2002/07/10 14:41:31 art Exp $	*/

 /*
  * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

 #ifdef STARBOARD
 #include "libevent-starboard.h"

 #include <assert.h>
 #include <sys/types.h>
 #include <sys/event.h>
 #include <sys/socket.h>

 // Use libevent's local compatibility  versions of these.
 #include "third_party/libevent/compat/sys/queue.h"
 #include "third_party/libevent/compat/sys/_libevent_time.h"

 // Include Starboard poems after all system headers.
 #include "starboard/client_porting/poem/stdio_poem.h"
 #include "starboard/client_porting/poem/string_poem.h"
 #else  // STARBOARD
 #define _GNU_SOURCE 1

 #include <sys/types.h>
 #ifdef HAVE_SYS_TIME_H
 #include <sys/time.h>
 #else
 #include <sys/_libevent_time.h>
 #endif
 #include <sys/queue.h>
 #include <sys/event.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
 #include <assert.h>
 #ifdef HAVE_INTTYPES_H
 #include <inttypes.h>
 #endif
 #endif  // STARBOARD

 /* Some platforms apparently define the udata field of struct kevent as
  * intptr_t, whereas others define it as void*.  There doesn't seem to be an
  * easy way to tell them apart via autoconf, so we need to use OS macros. */
 #if defined(HAVE_INTTYPES_H) && !defined(__OpenBSD__) && !defined(__FreeBSD__) && !defined(__darwin__) && !defined(__APPLE__)
 #define PTR_TO_UDATA(x)	((intptr_t)(x))
 #else
 #define PTR_TO_UDATA(x)	(x)
 #endif

 #include "event.h"
 #include "event-internal.h"
 #ifndef STARBOARD
 #include "evsignal.h"
 #endif  // STARBOARD
 #include "log.h"

 #define EVLIST_X_KQINKERNEL	0x1000

 #define NEVENT		64

 struct kqop {
 	struct kevent *changes;
 	int nchanges;
 	struct kevent *events;
 #ifndef STARBOARD
 	struct event_list evsigevents[NSIG];
 #endif
 	int nevents;
 	int kq;
 	pid_t pid;
 };

 static void *kq_init	(struct event_base *);
 static int kq_add	(void *, struct event *);
 static int kq_del	(void *, struct event *);
 static int kq_dispatch	(struct event_base *, void *, struct timeval *);
 static int kq_insert	(struct kqop *, struct kevent *);
 static void kq_dealloc (struct event_base *, void *);

 const struct eventop kqops = {
 	"kqueue",
 	kq_init,
 	kq_add,
 	kq_del,
 	kq_dispatch,
 	kq_dealloc,
 	1 /* need reinit */
 };

 static void *
 kq_init(struct event_base *base)
 {
 	int i, kq;
 	struct kqop *kqueueop;

 	/* Disable kqueue when this environment variable is set */
 	if (evutil_getenv("EVENT_NOKQUEUE"))
 		return (NULL);

 	if (!(kqueueop = calloc(1, sizeof(struct kqop))))
 		return (NULL);

 	/* Initalize the kernel queue */

 	if ((kq = kqueue()) == -1) {
 		event_warn("kqueue");
 		free (kqueueop);
 		return (NULL);
 	}

 	kqueueop->kq = kq;

 	kqueueop->pid = getpid();

 	/* Initalize fields */
 	kqueueop->changes = malloc(NEVENT * sizeof(struct kevent));
 	if (kqueueop->changes == NULL) {
 		free (kqueueop);
 		return (NULL);
 	}
 	kqueueop->events = malloc(NEVENT * sizeof(struct kevent));
 	if (kqueueop->events == NULL) {
 		free (kqueueop->changes);
 		free (kqueueop);
 		return (NULL);
 	}
 	kqueueop->nevents = NEVENT;

 #ifndef STARBOARD
 	/* we need to keep track of multiple events per signal */
 	for (i = 0; i < NSIG; ++i) {
 		TAILQ_INIT(&kqueueop->evsigevents[i]);
 	}
 #endif


 	return (kqueueop);
 }

 static int
 kq_insert(struct kqop *kqop, struct kevent *kev)
 {
 	int nevents = kqop->nevents;

 	if (kqop->nchanges == nevents) {
 		struct kevent *newchange;
 		struct kevent *newresult;

 		nevents *= 2;

 		newchange = realloc(kqop->changes,
 				    nevents * sizeof(struct kevent));
 		if (newchange == NULL) {
 			event_warn("%s: malloc", __func__);
 			return (-1);
 		}
 		kqop->changes = newchange;

 		newresult = realloc(kqop->events,
 				    nevents * sizeof(struct kevent));

 		/*
 		 * If we fail, we don't have to worry about freeing,
 		 * the next realloc will pick it up.
 		 */
 		if (newresult == NULL) {
 			event_warn("%s: malloc", __func__);
 			return (-1);
 		}
 		kqop->events = newresult;

 		kqop->nevents = nevents;
 	}

 	memcpy(&kqop->changes[kqop->nchanges++], kev, sizeof(struct kevent));

 	event_debug(("%s: fd %d %s%s",
 		__func__, (int)kev->ident,
 		kev->filter == EVFILT_READ ? "EVFILT_READ" : "EVFILT_WRITE",
 		kev->flags == EV_DELETE ? " (del)" : ""));

 	return (0);
 }

 static void
 kq_sighandler(int sig)
 {
 	/* Do nothing here */
 }

 static int
 kq_dispatch(struct event_base *base, void *arg, struct timeval *tv)
 {
 	struct kqop *kqop = arg;
 	struct kevent *changes = kqop->changes;
 	struct kevent *events = kqop->events;
 	struct event *ev;
 	struct timespec ts, *ts_p = NULL;
 	int i, res;

 	if (tv != NULL) {
 		TIMEVAL_TO_TIMESPEC(tv, &ts);
 		ts_p = &ts;
 	}

 	res = kevent(kqop->kq, changes, kqop->nchanges,
 	    events, kqop->nevents, ts_p);
 	kqop->nchanges = 0;
 	if (res == -1) {
 		if (errno != EINTR) {
                         event_warn("kevent");
 			return (-1);
 		}

 		return (0);
 	}

 	event_debug(("%s: kevent reports %d", __func__, res));

 	for (i = 0; i < res; i++) {
 		int which = 0;

 		if (events[i].flags & EV_ERROR) {
 			/*
 			 * Error messages that can happen, when a delete fails.
 			 *   EBADF happens when the file discriptor has been
 			 *   closed,
 			 *   ENOENT when the file discriptor was closed and
 			 *   then reopened.
 			 *   EINVAL for some reasons not understood; EINVAL
 			 *   should not be returned ever; but FreeBSD does :-\
 			 * An error is also indicated when a callback deletes
 			 * an event we are still processing.  In that case
 			 * the data field is set to ENOENT.
 			 */
 			if (events[i].data == EBADF ||
 			    events[i].data == EINVAL ||
 			    events[i].data == ENOENT)
 				continue;
 			errno = events[i].data;
 			return (-1);
 		}

 		if (events[i].filter == EVFILT_READ) {
 			which |= EV_READ;
 		} else if (events[i].filter == EVFILT_WRITE) {
 			which |= EV_WRITE;
 		} else if (events[i].filter == EVFILT_SIGNAL) {
 			which |= EV_SIGNAL;
 		}

 		if (!which)
 			continue;

 		if (events[i].filter == EVFILT_SIGNAL) {
 			struct event_list *head =
 			    (struct event_list *)events[i].udata;
 			TAILQ_FOREACH(ev, head, ev_signal_next) {
 				event_active(ev, which, events[i].data);
 			}
 		} else {
 			ev = (struct event *)events[i].udata;

 			if (!(ev->ev_events & EV_PERSIST))
 				ev->ev_flags &= ~EVLIST_X_KQINKERNEL;

 			event_active(ev, which, 1);
 		}
 	}

 	return (0);
 }


 static int
 kq_add(void *arg, struct event *ev)
 {
 	struct kqop *kqop = arg;
 	struct kevent kev;

 #ifndef STARBOARD
 	if (ev->ev_events & EV_SIGNAL) {
 		int nsignal = EVENT_SIGNAL(ev);

 		assert(nsignal >= 0 && nsignal < NSIG);
 		if (TAILQ_EMPTY(&kqop->evsigevents[nsignal])) {
 			struct timespec timeout = { 0, 0 };

 			memset(&kev, 0, sizeof(kev));
 			kev.ident = nsignal;
 			kev.filter = EVFILT_SIGNAL;
 			kev.flags = EV_ADD;
 			kev.udata = PTR_TO_UDATA(&kqop->evsigevents[nsignal]);

 			/* Be ready for the signal if it is sent any
 			 * time between now and the next call to
 			 * kq_dispatch. */
 			if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
 				return (-1);

 			if (_evsignal_set_handler(ev->ev_base, nsignal,
 				kq_sighandler) == -1)
 				return (-1);
 		}

 		TAILQ_INSERT_TAIL(&kqop->evsigevents[nsignal], ev,
 		    ev_signal_next);
 		ev->ev_flags |= EVLIST_X_KQINKERNEL;
 		return (0);
 	}
 #endif

 	if (ev->ev_events & EV_READ) {
  		memset(&kev, 0, sizeof(kev));
 		kev.ident = ev->ev_fd;
 		kev.filter = EVFILT_READ;
 #ifdef NOTE_EOF
 		/* Make it behave like select() and poll() */
 		kev.fflags = NOTE_EOF;
 #endif
 		kev.flags = EV_ADD;
 		if (!(ev->ev_events & EV_PERSIST))
 			kev.flags |= EV_ONESHOT;
 		kev.udata = PTR_TO_UDATA(ev);

 		if (kq_insert(kqop, &kev) == -1)
 			return (-1);

 		ev->ev_flags |= EVLIST_X_KQINKERNEL;
 	}

 	if (ev->ev_events & EV_WRITE) {
  		memset(&kev, 0, sizeof(kev));
 		kev.ident = ev->ev_fd;
 		kev.filter = EVFILT_WRITE;
 		kev.flags = EV_ADD;
 		if (!(ev->ev_events & EV_PERSIST))
 			kev.flags |= EV_ONESHOT;
 		kev.udata = PTR_TO_UDATA(ev);

 		if (kq_insert(kqop, &kev) == -1)
 			return (-1);

 		ev->ev_flags |= EVLIST_X_KQINKERNEL;
 	}

 	return (0);
 }

 static int
 kq_del(void *arg, struct event *ev)
 {
 	struct kqop *kqop = arg;
 	struct kevent kev;

 	if (!(ev->ev_flags & EVLIST_X_KQINKERNEL))
 		return (0);

 #ifndef STARBOARD
 	if (ev->ev_events & EV_SIGNAL) {
 		int nsignal = EVENT_SIGNAL(ev);
 		struct timespec timeout = { 0, 0 };

 		assert(nsignal >= 0 && nsignal < NSIG);
 		TAILQ_REMOVE(&kqop->evsigevents[nsignal], ev, ev_signal_next);
 		if (TAILQ_EMPTY(&kqop->evsigevents[nsignal])) {
 			memset(&kev, 0, sizeof(kev));
 			kev.ident = nsignal;
 			kev.filter = EVFILT_SIGNAL;
 			kev.flags = EV_DELETE;

 			/* Because we insert signal events
 			 * immediately, we need to delete them
 			 * immediately, too */
 			if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
 				return (-1);

 			if (_evsignal_restore_handler(ev->ev_base,
 				nsignal) == -1)
 				return (-1);
 		}

 		ev->ev_flags &= ~EVLIST_X_KQINKERNEL;
 		return (0);
 	}
 #endif

 	if (ev->ev_events & EV_READ) {
  		memset(&kev, 0, sizeof(kev));
 		kev.ident = ev->ev_fd;
 		kev.filter = EVFILT_READ;
 		kev.flags = EV_DELETE;

 		if (kq_insert(kqop, &kev) == -1)
 			return (-1);

 		ev->ev_flags &= ~EVLIST_X_KQINKERNEL;
 	}

 	if (ev->ev_events & EV_WRITE) {
  		memset(&kev, 0, sizeof(kev));
 		kev.ident = ev->ev_fd;
 		kev.filter = EVFILT_WRITE;
 		kev.flags = EV_DELETE;

 		if (kq_insert(kqop, &kev) == -1)
 			return (-1);

 		ev->ev_flags &= ~EVLIST_X_KQINKERNEL;
 	}

 	return (0);
 }

 static void
 kq_dealloc(struct event_base *base, void *arg)
 {
 	struct kqop *kqop = arg;

 	evsignal_dealloc(base);

 	if (kqop->changes)
 		free(kqop->changes);
 	if (kqop->events)
 		free(kqop->events);
 	if (kqop->kq >= 0 && kqop->pid == getpid())
 		close(kqop->kq);

 	memset(kqop, 0, sizeof(struct kqop));
 	free(kqop);
 }
	/* $OpenBSD: kqueue.c,v 1.5 2002/07/10 14:41:31 art Exp $ */

	/*
	* Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/
	#ifdef HAVE_CONFIG_H
	#include "config.h"
	#endif

	#ifdef STARBOARD
	#include "libevent-starboard.h"

	#include <assert.h>
	#include <sys/types.h>
	#include <sys/event.h>
	#include <sys/socket.h>

	// Use libevent's local compatibility versions of these.
	#include "third_party/libevent/compat/sys/queue.h"
	#include "third_party/libevent/compat/sys/_libevent_time.h"

	// Include Starboard poems after all system headers.
	#include "starboard/client_porting/poem/stdio_poem.h"
	#include "starboard/client_porting/poem/string_poem.h"
	#else // STARBOARD
	#define _GNU_SOURCE 1

	#include <sys/types.h>
	#ifdef HAVE_SYS_TIME_H
	#include <sys/time.h>
	#else
	#include <sys/_libevent_time.h>
	#endif
	#include <sys/queue.h>
	#include <sys/event.h>
	#include <signal.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>
	#include <errno.h>
	#include <assert.h>
	#ifdef HAVE_INTTYPES_H
	#include <inttypes.h>
	#endif
	#endif // STARBOARD

	/* Some platforms apparently define the udata field of struct kevent as
	* intptr_t, whereas others define it as void*. There doesn't seem to be an
	* easy way to tell them apart via autoconf, so we need to use OS macros. */
	#if defined(HAVE_INTTYPES_H) && !defined(__OpenBSD__) && !defined(__FreeBSD__) && !defined(__darwin__) && !defined(__APPLE__)
	#define PTR_TO_UDATA(x) ((intptr_t)(x))
	#else
	#define PTR_TO_UDATA(x) (x)
	#endif

	#include "event.h"
	#include "event-internal.h"
	#ifndef STARBOARD
	#include "evsignal.h"
	#endif // STARBOARD
	#include "log.h"

	#define EVLIST_X_KQINKERNEL 0x1000

	#define NEVENT 64

	struct kqop {
	struct kevent *changes;
	int nchanges;
	struct kevent *events;
	#ifndef STARBOARD
	struct event_list evsigevents[NSIG];
	#endif
	int nevents;
	int kq;
	pid_t pid;
	};

	static void kq_init (struct event_base );
	static int kq_add (void , struct event );
	static int kq_del (void , struct event );
	static int kq_dispatch (struct event_base , void , struct timeval *);
	static int kq_insert (struct kqop , struct kevent );
	static void kq_dealloc (struct event_base , void );

	const struct eventop kqops = {
	"kqueue",
	kq_init,
	kq_add,
	kq_del,
	kq_dispatch,
	kq_dealloc,
	1 /* need reinit */
	};

	static void *
	kq_init(struct event_base *base)
	{
	int i, kq;
	struct kqop *kqueueop;

	/* Disable kqueue when this environment variable is set */
	if (evutil_getenv("EVENT_NOKQUEUE"))
	return (NULL);

	if (!(kqueueop = calloc(1, sizeof(struct kqop))))
	return (NULL);

	/* Initalize the kernel queue */

	if ((kq = kqueue()) == -1) {
	event_warn("kqueue");
	free (kqueueop);
	return (NULL);
	}

	kqueueop->kq = kq;

	kqueueop->pid = getpid();

	/* Initalize fields */
	kqueueop->changes = malloc(NEVENT * sizeof(struct kevent));
	if (kqueueop->changes == NULL) {
	free (kqueueop);
	return (NULL);
	}
	kqueueop->events = malloc(NEVENT * sizeof(struct kevent));
	if (kqueueop->events == NULL) {
	free (kqueueop->changes);
	free (kqueueop);
	return (NULL);
	}
	kqueueop->nevents = NEVENT;

	#ifndef STARBOARD
	/* we need to keep track of multiple events per signal */
	for (i = 0; i < NSIG; ++i) {
	TAILQ_INIT(&kqueueop->evsigevents[i]);
	}
	#endif


	return (kqueueop);
	}

	static int
	kq_insert(struct kqop kqop, struct kevent kev)
	{
	int nevents = kqop->nevents;

	if (kqop->nchanges == nevents) {
	struct kevent *newchange;
	struct kevent *newresult;

	nevents *= 2;

	newchange = realloc(kqop->changes,
	nevents * sizeof(struct kevent));
	if (newchange == NULL) {
	event_warn("%s: malloc", __func__);
	return (-1);
	}
	kqop->changes = newchange;

	newresult = realloc(kqop->events,
	nevents * sizeof(struct kevent));

	/*
	* If we fail, we don't have to worry about freeing,
	* the next realloc will pick it up.
	*/
	if (newresult == NULL) {
	event_warn("%s: malloc", __func__);
	return (-1);
	}
	kqop->events = newresult;

	kqop->nevents = nevents;
	}

	memcpy(&kqop->changes[kqop->nchanges++], kev, sizeof(struct kevent));

	event_debug(("%s: fd %d %s%s",
	__func__, (int)kev->ident,
	kev->filter == EVFILT_READ ? "EVFILT_READ" : "EVFILT_WRITE",
	kev->flags == EV_DELETE ? " (del)" : ""));

	return (0);
	}

	static void
	kq_sighandler(int sig)
	{
	/* Do nothing here */
	}

	static int
	kq_dispatch(struct event_base base, void arg, struct timeval *tv)
	{
	struct kqop *kqop = arg;
	struct kevent *changes = kqop->changes;
	struct kevent *events = kqop->events;
	struct event *ev;
	struct timespec ts, *ts_p = NULL;
	int i, res;

	if (tv != NULL) {
	TIMEVAL_TO_TIMESPEC(tv, &ts);
	ts_p = &ts;
	}

	res = kevent(kqop->kq, changes, kqop->nchanges,
	events, kqop->nevents, ts_p);
	kqop->nchanges = 0;
	if (res == -1) {
	if (errno != EINTR) {
	event_warn("kevent");
	return (-1);
	}

	return (0);
	}

	event_debug(("%s: kevent reports %d", __func__, res));

	for (i = 0; i < res; i++) {
	int which = 0;

	if (events[i].flags & EV_ERROR) {
	/*
	* Error messages that can happen, when a delete fails.
	* EBADF happens when the file discriptor has been
	* closed,
	* ENOENT when the file discriptor was closed and
	* then reopened.
	* EINVAL for some reasons not understood; EINVAL
	* should not be returned ever; but FreeBSD does :-\
	* An error is also indicated when a callback deletes
	* an event we are still processing. In that case
	* the data field is set to ENOENT.
	*/
	if (events[i].data == EBADF \|\|
	events[i].data == EINVAL \|\|
	events[i].data == ENOENT)
	continue;
	errno = events[i].data;
	return (-1);
	}

	if (events[i].filter == EVFILT_READ) {
	which \|= EV_READ;
	} else if (events[i].filter == EVFILT_WRITE) {
	which \|= EV_WRITE;
	} else if (events[i].filter == EVFILT_SIGNAL) {
	which \|= EV_SIGNAL;
	}

	if (!which)
	continue;

	if (events[i].filter == EVFILT_SIGNAL) {
	struct event_list *head =
	(struct event_list *)events[i].udata;
	TAILQ_FOREACH(ev, head, ev_signal_next) {
	event_active(ev, which, events[i].data);
	}
	} else {
	ev = (struct event *)events[i].udata;

	if (!(ev->ev_events & EV_PERSIST))
	ev->ev_flags &= ~EVLIST_X_KQINKERNEL;

	event_active(ev, which, 1);
	}
	}

	return (0);
	}


	static int
	kq_add(void arg, struct event ev)
	{
	struct kqop *kqop = arg;
	struct kevent kev;

	#ifndef STARBOARD
	if (ev->ev_events & EV_SIGNAL) {
	int nsignal = EVENT_SIGNAL(ev);

	assert(nsignal >= 0 && nsignal < NSIG);
	if (TAILQ_EMPTY(&kqop->evsigevents[nsignal])) {
	struct timespec timeout = { 0, 0 };

	memset(&kev, 0, sizeof(kev));
	kev.ident = nsignal;
	kev.filter = EVFILT_SIGNAL;
	kev.flags = EV_ADD;
	kev.udata = PTR_TO_UDATA(&kqop->evsigevents[nsignal]);

	/* Be ready for the signal if it is sent any
	* time between now and the next call to
	* kq_dispatch. */
	if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
	return (-1);

	if (_evsignal_set_handler(ev->ev_base, nsignal,
	kq_sighandler) == -1)
	return (-1);
	}

	TAILQ_INSERT_TAIL(&kqop->evsigevents[nsignal], ev,
	ev_signal_next);
	ev->ev_flags \|= EVLIST_X_KQINKERNEL;
	return (0);
	}
	#endif

	if (ev->ev_events & EV_READ) {
	memset(&kev, 0, sizeof(kev));
	kev.ident = ev->ev_fd;
	kev.filter = EVFILT_READ;
	#ifdef NOTE_EOF
	/* Make it behave like select() and poll() */
	kev.fflags = NOTE_EOF;
	#endif
	kev.flags = EV_ADD;
	if (!(ev->ev_events & EV_PERSIST))
	kev.flags \|= EV_ONESHOT;
	kev.udata = PTR_TO_UDATA(ev);

	if (kq_insert(kqop, &kev) == -1)
	return (-1);

	ev->ev_flags \|= EVLIST_X_KQINKERNEL;
	}

	if (ev->ev_events & EV_WRITE) {
	memset(&kev, 0, sizeof(kev));
	kev.ident = ev->ev_fd;
	kev.filter = EVFILT_WRITE;
	kev.flags = EV_ADD;
	if (!(ev->ev_events & EV_PERSIST))
	kev.flags \|= EV_ONESHOT;
	kev.udata = PTR_TO_UDATA(ev);

	if (kq_insert(kqop, &kev) == -1)
	return (-1);

	ev->ev_flags \|= EVLIST_X_KQINKERNEL;
	}

	return (0);
	}

	static int
	kq_del(void arg, struct event ev)
	{
	struct kqop *kqop = arg;
	struct kevent kev;

	if (!(ev->ev_flags & EVLIST_X_KQINKERNEL))
	return (0);

	#ifndef STARBOARD
	if (ev->ev_events & EV_SIGNAL) {
	int nsignal = EVENT_SIGNAL(ev);
	struct timespec timeout = { 0, 0 };

	assert(nsignal >= 0 && nsignal < NSIG);
	TAILQ_REMOVE(&kqop->evsigevents[nsignal], ev, ev_signal_next);
	if (TAILQ_EMPTY(&kqop->evsigevents[nsignal])) {
	memset(&kev, 0, sizeof(kev));
	kev.ident = nsignal;
	kev.filter = EVFILT_SIGNAL;
	kev.flags = EV_DELETE;

	/* Because we insert signal events
	* immediately, we need to delete them
	* immediately, too */
	if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
	return (-1);

	if (_evsignal_restore_handler(ev->ev_base,
	nsignal) == -1)
	return (-1);
	}

	ev->ev_flags &= ~EVLIST_X_KQINKERNEL;
	return (0);
	}
	#endif

	if (ev->ev_events & EV_READ) {
	memset(&kev, 0, sizeof(kev));
	kev.ident = ev->ev_fd;
	kev.filter = EVFILT_READ;
	kev.flags = EV_DELETE;

	if (kq_insert(kqop, &kev) == -1)
	return (-1);

	ev->ev_flags &= ~EVLIST_X_KQINKERNEL;
	}

	if (ev->ev_events & EV_WRITE) {
	memset(&kev, 0, sizeof(kev));
	kev.ident = ev->ev_fd;
	kev.filter = EVFILT_WRITE;
	kev.flags = EV_DELETE;

	if (kq_insert(kqop, &kev) == -1)
	return (-1);

	ev->ev_flags &= ~EVLIST_X_KQINKERNEL;
	}

	return (0);
	}

	static void
	kq_dealloc(struct event_base base, void arg)
	{
	struct kqop *kqop = arg;

	evsignal_dealloc(base);

	if (kqop->changes)
	free(kqop->changes);
	if (kqop->events)
	free(kqop->events);
	if (kqop->kq >= 0 && kqop->pid == getpid())
	close(kqop->kq);

	memset(kqop, 0, sizeof(struct kqop));
	free(kqop);
	}