/*	$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);

}