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 /*	$OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $	*/

 /*

  * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>

  * Copyright 2007-2012 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>

 #ifdef _EVENT_HAVE_SYS_TIME_H

 #include <sys/time.h>

 #endif

 #include <sys/queue.h>

 #include <poll.h>

 #include <signal.h>

 #include <limits.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #include <unistd.h>

 #include <errno.h>

 #include "event-internal.h"

 #include "evsignal-internal.h"

 #include "log-internal.h"

 #include "evmap-internal.h"

 #include "event2/thread.h"

 #include "evthread-internal.h"

 struct pollidx {

 	int idxplus1;

 };

 struct pollop {

 	int event_count;		/* Highest number alloc */

 	int nfds;			/* Highest number used */

 	int realloc_copy;		/* True iff we must realloc

 					 * event_set_copy */

 	struct pollfd *event_set;

 	struct pollfd *event_set_copy;

 };

 static void *poll_init(struct event_base *);

 static int poll_add(struct event_base *, int, short old, short events, void *_idx);

 static int poll_del(struct event_base *, int, short old, short events, void *_idx);

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

 static void poll_dealloc(struct event_base *);

 const struct eventop pollops = {

 	"poll",

 	poll_init,

 	poll_add,

 	poll_del,

 	poll_dispatch,

 	poll_dealloc,

 	0, /* doesn't need_reinit */

 	EV_FEATURE_FDS,

 	sizeof(struct pollidx),

 };

 static void *

 poll_init(struct event_base *base)

 {

 	struct pollop *pollop;

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

 		return (NULL);

 	evsig_init(base);

 	return (pollop);

 }

 #ifdef CHECK_INVARIANTS

 static void

 poll_check_ok(struct pollop *pop)

 {

 	int i, idx;

 	struct event *ev;

 	for (i = 0; i < pop->fd_count; ++i) {

 		idx = pop->idxplus1_by_fd[i]-1;

 		if (idx < 0)

 			continue;

 		EVUTIL_ASSERT(pop->event_set[idx].fd == i);

 	}

 	for (i = 0; i < pop->nfds; ++i) {

 		struct pollfd *pfd = &pop->event_set[i];

 		EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);

 	}

 }

 #else

 #define poll_check_ok(pop)

 #endif

 static int

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

 {

 	int res, i, j, nfds;

 	long msec = -1;

 	struct pollop *pop = base->evbase;

 	struct pollfd *event_set;

 	poll_check_ok(pop);

 	nfds = pop->nfds;

 #ifndef _EVENT_DISABLE_THREAD_SUPPORT

 	if (base->th_base_lock) {

 		/* If we're using this backend in a multithreaded setting,

 		 * then we need to work on a copy of event_set, so that we can

 		 * let other threads modify the main event_set while we're

 		 * polling. If we're not multithreaded, then we'll skip the

 		 * copy step here to save memory and time. */

 		if (pop->realloc_copy) {

 			struct pollfd *tmp = mm_realloc(pop->event_set_copy,

 			    pop->event_count * sizeof(struct pollfd));

 			if (tmp == NULL) {

 				event_warn("realloc");

 				return -1;

 			}

 			pop->event_set_copy = tmp;

 			pop->realloc_copy = 0;

 		}

 		memcpy(pop->event_set_copy, pop->event_set,

 		    sizeof(struct pollfd)*nfds);

 		event_set = pop->event_set_copy;

 	} else {

 		event_set = pop->event_set;

 	}

 #else

 	event_set = pop->event_set;

 #endif

 	if (tv != NULL) {

 		msec = evutil_tv_to_msec(tv);

 		if (msec < 0 || msec > INT_MAX)

 			msec = INT_MAX;

 	}

 	EVBASE_RELEASE_LOCK(base, th_base_lock);

 	res = poll(event_set, nfds, msec);

 	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

 	if (res == -1) {

 		if (errno != EINTR) {

 			event_warn("poll");

 			return (-1);

 		}

 		return (0);

 	}

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

 	if (res == 0 || nfds == 0)

 		return (0);

 	i = random() % nfds;

 	for (j = 0; j < nfds; j++) {

 		int what;

 		if (++i == nfds)

 			i = 0;

 		what = event_set[i].revents;

 		if (!what)

 			continue;

 		res = 0;

 		/* If the file gets closed notify */

 		if (what & (POLLHUP|POLLERR))

 			what |= POLLIN|POLLOUT;

 		if (what & POLLIN)

 			res |= EV_READ;

 		if (what & POLLOUT)

 			res |= EV_WRITE;

 		if (res == 0)

 			continue;

 		evmap_io_active(base, event_set[i].fd, res);

 	}

 	return (0);

 }

 static int

 poll_add(struct event_base *base, int fd, short old, short events, void *_idx)

 {

 	struct pollop *pop = base->evbase;

 	struct pollfd *pfd = NULL;

 	struct pollidx *idx = _idx;

 	int i;

 	EVUTIL_ASSERT((events & EV_SIGNAL) == 0);

 	if (!(events & (EV_READ|EV_WRITE)))

 		return (0);

 	poll_check_ok(pop);

 	if (pop->nfds + 1 >= pop->event_count) {

 		struct pollfd *tmp_event_set;

 		int tmp_event_count;

 		if (pop->event_count < 32)

 			tmp_event_count = 32;

 		else

 			tmp_event_count = pop->event_count * 2;

 		/* We need more file descriptors */

 		tmp_event_set = mm_realloc(pop->event_set,

 				 tmp_event_count * sizeof(struct pollfd));

 		if (tmp_event_set == NULL) {

 			event_warn("realloc");

 			return (-1);

 		}

 		pop->event_set = tmp_event_set;

 		pop->event_count = tmp_event_count;

 		pop->realloc_copy = 1;

 	}

 	i = idx->idxplus1 - 1;

 	if (i >= 0) {

 		pfd = &pop->event_set[i];

 	} else {

 		i = pop->nfds++;

 		pfd = &pop->event_set[i];

 		pfd->events = 0;

 		pfd->fd = fd;

 		idx->idxplus1 = i + 1;

 	}

 	pfd->revents = 0;

 	if (events & EV_WRITE)

 		pfd->events |= POLLOUT;

 	if (events & EV_READ)

 		pfd->events |= POLLIN;

 	poll_check_ok(pop);

 	return (0);

 }

 /*

  * Nothing to be done here.

  */

 static int

 poll_del(struct event_base *base, int fd, short old, short events, void *_idx)

 {

 	struct pollop *pop = base->evbase;

 	struct pollfd *pfd = NULL;

 	struct pollidx *idx = _idx;

 	int i;

 	EVUTIL_ASSERT((events & EV_SIGNAL) == 0);

 	if (!(events & (EV_READ|EV_WRITE)))

 		return (0);

 	poll_check_ok(pop);

 	i = idx->idxplus1 - 1;

 	if (i < 0)

 		return (-1);

 	/* Do we still want to read or write? */

 	pfd = &pop->event_set[i];

 	if (events & EV_READ)

 		pfd->events &= ~POLLIN;

 	if (events & EV_WRITE)

 		pfd->events &= ~POLLOUT;

 	poll_check_ok(pop);

 	if (pfd->events)

 		/* Another event cares about that fd. */

 		return (0);

 	/* Okay, so we aren't interested in that fd anymore. */

 	idx->idxplus1 = 0;

 	--pop->nfds;

 	if (i != pop->nfds) {

 		/*

 		 * Shift the last pollfd down into the now-unoccupied

 		 * position.

 		 */

 		memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],

 		       sizeof(struct pollfd));

 		idx = evmap_io_get_fdinfo(&base->io, pop->event_set[i].fd);

 		EVUTIL_ASSERT(idx);

 		EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);

 		idx->idxplus1 = i + 1;

 	}

 	poll_check_ok(pop);

 	return (0);

 }

 static void

 poll_dealloc(struct event_base *base)

 {

 	struct pollop *pop = base->evbase;

 	evsig_dealloc(base);

 	if (pop->event_set)

 		mm_free(pop->event_set);

 	if (pop->event_set_copy)

 		mm_free(pop->event_set_copy);

 	memset(pop, 0, sizeof(struct pollop));

 	mm_free(pop);

 }