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 /*

  * Copyright 2000-2009 Niels Provos <provos@citi.umich.edu>

  * Copyright 2009-2012 Niels Provos and Nick Mathewson

  *

  * 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.

  */

 #include "event2/event-config.h"

 #include <sys/types.h>

 #include <sys/resource.h>

 #ifdef _EVENT_HAVE_SYS_TIME_H

 #include <sys/time.h>

 #endif

 #include <sys/queue.h>

 #include <sys/devpoll.h>

 #include <signal.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #include <unistd.h>

 #include <fcntl.h>

 #include <errno.h>

 #include "event2/event.h"

 #include "event2/event_struct.h"

 #include "event2/thread.h"

 #include "event-internal.h"

 #include "evsignal-internal.h"

 #include "log-internal.h"

 #include "evmap-internal.h"

 #include "evthread-internal.h"

 struct devpollop {

 	struct pollfd *events;

 	int nevents;

 	int dpfd;

 	struct pollfd *changes;

 	int nchanges;

 };

 static void *devpoll_init(struct event_base *);

 static int devpoll_add(struct event_base *, int fd, short old, short events, void *);

 static int devpoll_del(struct event_base *, int fd, short old, short events, void *);

 static int devpoll_dispatch(struct event_base *, struct timeval *);

 static void devpoll_dealloc(struct event_base *);

 const struct eventop devpollops = {

 	"devpoll",

 	devpoll_init,

 	devpoll_add,

 	devpoll_del,

 	devpoll_dispatch,

 	devpoll_dealloc,

 	1, /* need reinit */

 	EV_FEATURE_FDS|EV_FEATURE_O1,

 	0

 };

 #define NEVENT	32000

 static int

 devpoll_commit(struct devpollop *devpollop)

 {

 	/*

 	 * Due to a bug in Solaris, we have to use pwrite with an offset of 0.

 	 * Write is limited to 2GB of data, until it will fail.

 	 */

 	if (pwrite(devpollop->dpfd, devpollop->changes,

 		sizeof(struct pollfd) * devpollop->nchanges, 0) == -1)

 		return (-1);

 	devpollop->nchanges = 0;

 	return (0);

 }

 static int

 devpoll_queue(struct devpollop *devpollop, int fd, int events) {

 	struct pollfd *pfd;

 	if (devpollop->nchanges >= devpollop->nevents) {

 		/*

 		 * Change buffer is full, must commit it to /dev/poll before

 		 * adding more

 		 */

 		if (devpoll_commit(devpollop) != 0)

 			return (-1);

 	}

 	pfd = &devpollop->changes[devpollop->nchanges++];

 	pfd->fd = fd;

 	pfd->events = events;

 	pfd->revents = 0;

 	return (0);

 }

 static void *

 devpoll_init(struct event_base *base)

 {

 	int dpfd, nfiles = NEVENT;

 	struct rlimit rl;

 	struct devpollop *devpollop;

 	if (!(devpollop = mm_calloc(1, sizeof(struct devpollop))))

 		return (NULL);

 	if (getrlimit(RLIMIT_NOFILE, &rl) == 0 &&

 	    rl.rlim_cur != RLIM_INFINITY)

 		nfiles = rl.rlim_cur;

 	/* Initialize the kernel queue */

 	if ((dpfd = evutil_open_closeonexec("/dev/poll", O_RDWR, 0)) == -1) {

 		event_warn("open: /dev/poll");

 		mm_free(devpollop);

 		return (NULL);

 	}

 	devpollop->dpfd = dpfd;

 	/* Initialize fields */

 	/* FIXME: allocating 'nfiles' worth of space here can be

 	 * expensive and unnecessary.  See how epoll.c does it instead. */

 	devpollop->events = mm_calloc(nfiles, sizeof(struct pollfd));

 	if (devpollop->events == NULL) {

 		mm_free(devpollop);

 		close(dpfd);

 		return (NULL);

 	}

 	devpollop->nevents = nfiles;

 	devpollop->changes = mm_calloc(nfiles, sizeof(struct pollfd));

 	if (devpollop->changes == NULL) {

 		mm_free(devpollop->events);

 		mm_free(devpollop);

 		close(dpfd);

 		return (NULL);

 	}

 	evsig_init(base);

 	return (devpollop);

 }

 static int

 devpoll_dispatch(struct event_base *base, struct timeval *tv)

 {

 	struct devpollop *devpollop = base->evbase;

 	struct pollfd *events = devpollop->events;

 	struct dvpoll dvp;

 	int i, res, timeout = -1;

 	if (devpollop->nchanges)

 		devpoll_commit(devpollop);

 	if (tv != NULL)

 		timeout = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;

 	dvp.dp_fds = devpollop->events;

 	dvp.dp_nfds = devpollop->nevents;

 	dvp.dp_timeout = timeout;

 	EVBASE_RELEASE_LOCK(base, th_base_lock);

 	res = ioctl(devpollop->dpfd, DP_POLL, &dvp);

 	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

 	if (res == -1) {

 		if (errno != EINTR) {

 			event_warn("ioctl: DP_POLL");

 			return (-1);

 		}

 		return (0);

 	}

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

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

 		int which = 0;

 		int what = events[i].revents;

 		if (what & POLLHUP)

 			what |= POLLIN | POLLOUT;

 		else if (what & POLLERR)

 			what |= POLLIN | POLLOUT;

 		if (what & POLLIN)

 			which |= EV_READ;

 		if (what & POLLOUT)

 			which |= EV_WRITE;

 		if (!which)

 			continue;

 		/* XXX(niels): not sure if this works for devpoll */

 		evmap_io_active(base, events[i].fd, which);

 	}

 	return (0);

 }

 static int

 devpoll_add(struct event_base *base, int fd, short old, short events, void *p)

 {

 	struct devpollop *devpollop = base->evbase;

 	int res;

 	(void)p;

 	/*

 	 * It's not necessary to OR the existing read/write events that we

 	 * are currently interested in with the new event we are adding.

 	 * The /dev/poll driver ORs any new events with the existing events

 	 * that it has cached for the fd.

 	 */

 	res = 0;

 	if (events & EV_READ)

 		res |= POLLIN;

 	if (events & EV_WRITE)

 		res |= POLLOUT;

 	if (devpoll_queue(devpollop, fd, res) != 0)

 		return (-1);

 	return (0);

 }

 static int

 devpoll_del(struct event_base *base, int fd, short old, short events, void *p)

 {

 	struct devpollop *devpollop = base->evbase;

 	int res;

 	(void)p;

 	res = 0;

 	if (events & EV_READ)

 		res |= POLLIN;

 	if (events & EV_WRITE)

 		res |= POLLOUT;

 	/*

 	 * The only way to remove an fd from the /dev/poll monitored set is

 	 * to use POLLREMOVE by itself.  This removes ALL events for the fd

 	 * provided so if we care about two events and are only removing one

 	 * we must re-add the other event after POLLREMOVE.

 	 */

 	if (devpoll_queue(devpollop, fd, POLLREMOVE) != 0)

 		return (-1);

 	if ((res & (POLLIN|POLLOUT)) != (POLLIN|POLLOUT)) {

 		/*

 		 * We're not deleting all events, so we must resubmit the

 		 * event that we are still interested in if one exists.

 		 */

 		if ((res & POLLIN) && (old & EV_WRITE)) {

 			/* Deleting read, still care about write */

 			devpoll_queue(devpollop, fd, POLLOUT);

 		} else if ((res & POLLOUT) && (old & EV_READ)) {

 			/* Deleting write, still care about read */

 			devpoll_queue(devpollop, fd, POLLIN);

 		}

 	}

 	return (0);

 }

 static void

 devpoll_dealloc(struct event_base *base)

 {

 	struct devpollop *devpollop = base->evbase;

 	evsig_dealloc(base);

 	if (devpollop->events)

 		mm_free(devpollop->events);

 	if (devpollop->changes)

 		mm_free(devpollop->changes);

 	if (devpollop->dpfd >= 0)

 		close(devpollop->dpfd);

 	memset(devpollop, 0, sizeof(struct devpollop));

 	mm_free(devpollop);

 }