/*

 * Submitted by David Pacheco (dp.spambait@gmail.com)

 *

 * Copyright 2006-2007 Niels Provos

 * 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 SUN MICROSYSTEMS, INC. ``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 SUN MICROSYSTEMS, INC. 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.

 */

/*

 * Copyright (c) 2007 Sun Microsystems. All rights reserved.

 * Use is subject to license terms.

 */

/*

 * evport.c: event backend using Solaris 10 event ports. See port_create(3C).

 * This implementation is loosely modeled after the one used for select(2) (in

 * select.c).

 *

 * The outstanding events are tracked in a data structure called evport_data.

 * Each entry in the ed_fds array corresponds to a file descriptor, and contains

 * pointers to the read and write events that correspond to that fd. (That is,

 * when the file is readable, the "read" event should handle it, etc.)

 *

 * evport_add and evport_del update this data structure. evport_dispatch uses it

 * to determine where to callback when an event occurs (which it gets from

 * port_getn).

 *

 * Helper functions are used: grow() grows the file descriptor array as

 * necessary when large fd's come in. reassociate() takes care of maintaining

 * the proper file-descriptor/event-port associations.

 *

 * As in the select(2) implementation, signals are handled by evsignal.

 */

#include "event2/event-config.h"

#include <sys/time.h>

#include <sys/queue.h>

#include <errno.h>

#include <poll.h>

#include <port.h>

#include <signal.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <time.h>

#include <unistd.h>

#include "event2/thread.h"

#include "evthread-internal.h"

#include "event-internal.h"

#include "log-internal.h"

#include "evsignal-internal.h"

#include "evmap-internal.h"

/*

 * Default value for ed_nevents, which is the maximum file descriptor number we

 * can handle. If an event comes in for a file descriptor F > nevents, we will

 * grow the array of file descriptors, doubling its size.

 */

#define DEFAULT_NFDS	16

/*

 * EVENTS_PER_GETN is the maximum number of events to retrieve from port_getn on

 * any particular call. You can speed things up by increasing this, but it will

 * (obviously) require more memory.

 */

#define EVENTS_PER_GETN 8

/*

 * Per-file-descriptor information about what events we're subscribed to. These

 * fields are NULL if no event is subscribed to either of them.

 */

struct fd_info {

	short fdi_what;		/* combinations of EV_READ and EV_WRITE */

};

#define FDI_HAS_READ(fdi)  ((fdi)->fdi_what & EV_READ)

#define FDI_HAS_WRITE(fdi) ((fdi)->fdi_what & EV_WRITE)

#define FDI_HAS_EVENTS(fdi) (FDI_HAS_READ(fdi) || FDI_HAS_WRITE(fdi))

#define FDI_TO_SYSEVENTS(fdi) (FDI_HAS_READ(fdi) ? POLLIN : 0) | \

    (FDI_HAS_WRITE(fdi) ? POLLOUT : 0)

struct evport_data {

	int		ed_port;	/* event port for system events  */

	int		ed_nevents;	/* number of allocated fdi's	 */

	struct fd_info *ed_fds;		/* allocated fdi table		 */

	/* fdi's that we need to reassoc */

	int ed_pending[EVENTS_PER_GETN]; /* fd's with pending events */

};

static void*	evport_init(struct event_base *);

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

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

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

static void	evport_dealloc(struct event_base *);

const struct eventop evportops = {

	"evport",

	evport_init,

	evport_add,

	evport_del,

	evport_dispatch,

	evport_dealloc,

	1, /* need reinit */

	0, /* features */

	0, /* fdinfo length */

};

/*

 * Initialize the event port implementation.

 */

static void*

evport_init(struct event_base *base)

{

	struct evport_data *evpd;

	int i;

	if (!(evpd = mm_calloc(1, sizeof(struct evport_data))))

		return (NULL);

	if ((evpd->ed_port = port_create()) == -1) {

		mm_free(evpd);

		return (NULL);

	}

	/*

	 * Initialize file descriptor structure

	 */

	evpd->ed_fds = mm_calloc(DEFAULT_NFDS, sizeof(struct fd_info));

	if (evpd->ed_fds == NULL) {

		close(evpd->ed_port);

		mm_free(evpd);

		return (NULL);

	}

	evpd->ed_nevents = DEFAULT_NFDS;

	for (i = 0; i < EVENTS_PER_GETN; i++)

		evpd->ed_pending[i] = -1;

	evsig_init(base);

	return (evpd);

}

#ifdef CHECK_INVARIANTS

/*

 * Checks some basic properties about the evport_data structure. Because it

 * checks all file descriptors, this function can be expensive when the maximum

 * file descriptor ever used is rather large.

 */

static void

check_evportop(struct evport_data *evpd)

{

	EVUTIL_ASSERT(evpd);

	EVUTIL_ASSERT(evpd->ed_nevents > 0);

	EVUTIL_ASSERT(evpd->ed_port > 0);

	EVUTIL_ASSERT(evpd->ed_fds > 0);

}

/*

 * Verifies very basic integrity of a given port_event.

 */

static void

check_event(port_event_t* pevt)

{

	/*

	 * We've only registered for PORT_SOURCE_FD events. The only

	 * other thing we can legitimately receive is PORT_SOURCE_ALERT,

	 * but since we're not using port_alert either, we can assume

	 * PORT_SOURCE_FD.

	 */

	EVUTIL_ASSERT(pevt->portev_source == PORT_SOURCE_FD);

	EVUTIL_ASSERT(pevt->portev_user == NULL);

}

#else

#define check_evportop(epop)

#define check_event(pevt)

#endif /* CHECK_INVARIANTS */

/*

 * Doubles the size of the allocated file descriptor array.

 */

static int

grow(struct evport_data *epdp, int factor)

{

	struct fd_info *tmp;

	int oldsize = epdp->ed_nevents;

	int newsize = factor * oldsize;

	EVUTIL_ASSERT(factor > 1);

	check_evportop(epdp);

	tmp = mm_realloc(epdp->ed_fds, sizeof(struct fd_info) * newsize);

	if (NULL == tmp)

		return -1;

	epdp->ed_fds = tmp;

	memset((char*) (epdp->ed_fds + oldsize), 0,

	    (newsize - oldsize)*sizeof(struct fd_info));

	epdp->ed_nevents = newsize;

	check_evportop(epdp);

	return 0;

}

/*

 * (Re)associates the given file descriptor with the event port. The OS events

 * are specified (implicitly) from the fd_info struct.

 */

static int

reassociate(struct evport_data *epdp, struct fd_info *fdip, int fd)

{

	int sysevents = FDI_TO_SYSEVENTS(fdip);

	if (sysevents != 0) {

		if (port_associate(epdp->ed_port, PORT_SOURCE_FD,

				   fd, sysevents, NULL) == -1) {

			event_warn("port_associate");

			return (-1);

		}

	}

	check_evportop(epdp);

	return (0);

}

/*

 * Main event loop - polls port_getn for some number of events, and processes

 * them.

 */

static int

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

{

	int i, res;

	struct evport_data *epdp = base->evbase;

	port_event_t pevtlist[EVENTS_PER_GETN];

	/*

	 * port_getn will block until it has at least nevents events. It will

	 * also return how many it's given us (which may be more than we asked

	 * for, as long as it's less than our maximum (EVENTS_PER_GETN)) in

	 * nevents.

	 */

	int nevents = 1;

	/*

	 * We have to convert a struct timeval to a struct timespec

	 * (only difference is nanoseconds vs. microseconds). If no time-based

	 * events are active, we should wait for I/O (and tv == NULL).

	 */

	struct timespec ts;

	struct timespec *ts_p = NULL;

	if (tv != NULL) {

		ts.tv_sec = tv->tv_sec;

		ts.tv_nsec = tv->tv_usec * 1000;

		ts_p = &ts;

	}

	/*

	 * Before doing anything else, we need to reassociate the events we hit

	 * last time which need reassociation. See comment at the end of the

	 * loop below.

	 */

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

		struct fd_info *fdi = NULL;

		if (epdp->ed_pending[i] != -1) {

			fdi = &(epdp->ed_fds[epdp->ed_pending[i]]);

		}

		if (fdi != NULL && FDI_HAS_EVENTS(fdi)) {

			int fd = epdp->ed_pending[i];

			reassociate(epdp, fdi, fd);

			epdp->ed_pending[i] = -1;

		}

	}

	EVBASE_RELEASE_LOCK(base, th_base_lock);

	res = port_getn(epdp->ed_port, pevtlist, EVENTS_PER_GETN,

	    (unsigned int *) &nevents, ts_p);

	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

	if (res == -1) {

		if (errno == EINTR || errno == EAGAIN) {

			return (0);

		} else if (errno == ETIME) {

			if (nevents == 0)

				return (0);

		} else {

			event_warn("port_getn");

			return (-1);

		}

	}

	event_debug(("%s: port_getn reports %d events", __func__, nevents));

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

		struct fd_info *fdi;

		port_event_t *pevt = &pevtlist[i];

		int fd = (int) pevt->portev_object;

		check_evportop(epdp);

		check_event(pevt);

		epdp->ed_pending[i] = fd;

		/*

		 * Figure out what kind of event it was

		 * (because we have to pass this to the callback)

		 */

		res = 0;

		if (pevt->portev_events & (POLLERR|POLLHUP)) {

			res = EV_READ | EV_WRITE;

		} else {

			if (pevt->portev_events & POLLIN)

				res |= EV_READ;

			if (pevt->portev_events & POLLOUT)

				res |= EV_WRITE;

		}

		/*

		 * Check for the error situations or a hangup situation

		 */

		if (pevt->portev_events & (POLLERR|POLLHUP|POLLNVAL))

			res |= EV_READ|EV_WRITE;

		EVUTIL_ASSERT(epdp->ed_nevents > fd);

		fdi = &(epdp->ed_fds[fd]);

		evmap_io_active(base, fd, res);

	} /* end of all events gotten */

	check_evportop(epdp);

	return (0);

}

/*

 * Adds the given event (so that you will be notified when it happens via

 * the callback function).

 */

static int

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

{

	struct evport_data *evpd = base->evbase;

	struct fd_info *fdi;

	int factor;

	(void)p;

	check_evportop(evpd);

	/*

	 * If necessary, grow the file descriptor info table

	 */

	factor = 1;

	while (fd >= factor * evpd->ed_nevents)

		factor *= 2;

	if (factor > 1) {

		if (-1 == grow(evpd, factor)) {

			return (-1);

		}

	}

	fdi = &evpd->ed_fds[fd];

	fdi->fdi_what |= events;

	return reassociate(evpd, fdi, fd);

}

/*

 * Removes the given event from the list of events to wait for.

 */

static int

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

{

	struct evport_data *evpd = base->evbase;

	struct fd_info *fdi;

	int i;

	int associated = 1;

	(void)p;

	check_evportop(evpd);

	if (evpd->ed_nevents < fd) {

		return (-1);

	}

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

		if (evpd->ed_pending[i] == fd) {

			associated = 0;

			break;

		}

	}

	fdi = &evpd->ed_fds[fd];

	if (events & EV_READ)

		fdi->fdi_what &= ~EV_READ;

	if (events & EV_WRITE)

		fdi->fdi_what &= ~EV_WRITE;

	if (associated) {

		if (!FDI_HAS_EVENTS(fdi) &&

		    port_dissociate(evpd->ed_port, PORT_SOURCE_FD, fd) == -1) {

			/*

			 * Ignore EBADFD error the fd could have been closed

			 * before event_del() was called.

			 */

			if (errno != EBADFD) {

				event_warn("port_dissociate");

				return (-1);

			}

		} else {

			if (FDI_HAS_EVENTS(fdi)) {

				return (reassociate(evpd, fdi, fd));

			}

		}

	} else {

		if ((fdi->fdi_what & (EV_READ|EV_WRITE)) == 0) {

			evpd->ed_pending[i] = -1;

		}

	}

	return 0;

}

static void

evport_dealloc(struct event_base *base)

{

	struct evport_data *evpd = base->evbase;

	evsig_dealloc(base);

	close(evpd->ed_port);

	if (evpd->ed_fds)

		mm_free(evpd->ed_fds);

	mm_free(evpd);

}