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

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

 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif

 #include <sys/time.h>
 #include <assert.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>
 #ifdef CHECK_INVARIANTS
 #include <assert.h>
 #endif

 #include "event.h"
 #include "event-internal.h"
 #include "log.h"
 #include "evsignal.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 {
 	struct event* fdi_revt; /* the event responsible for the "read"  */
 	struct event* fdi_wevt; /* the event responsible for the "write" */
 };

 #define FDI_HAS_READ(fdi)  ((fdi)->fdi_revt != NULL)
 #define FDI_HAS_WRITE(fdi) ((fdi)->fdi_wevt != NULL)
 #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	(void *, struct event *);
 static int 	evport_del	(void *, struct event *);
 static int 	evport_dispatch	(struct event_base *, void *, struct timeval *);
 static void	evport_dealloc	(struct event_base *, void *);

 const struct eventop evportops = {
 	"evport",
 	evport_init,
 	evport_add,
 	evport_del,
 	evport_dispatch,
 	evport_dealloc,
 	1 /* need reinit */
 };

 /*
  * Initialize the event port implementation.
  */

 static void*
 evport_init(struct event_base *base)
 {
 	struct evport_data *evpd;
 	int i;
 	/*
 	 * Disable event ports when this environment variable is set
 	 */
 	if (evutil_getenv("EVENT_NOEVPORT"))
 		return (NULL);

 	if (!(evpd = calloc(1, sizeof(struct evport_data))))
 		return (NULL);

 	if ((evpd->ed_port = port_create()) == -1) {
 		free(evpd);
 		return (NULL);
 	}

 	/*
 	 * Initialize file descriptor structure
 	 */
 	evpd->ed_fds = calloc(DEFAULT_NFDS, sizeof(struct fd_info));
 	if (evpd->ed_fds == NULL) {
 		close(evpd->ed_port);
 		free(evpd);
 		return (NULL);
 	}
 	evpd->ed_nevents = DEFAULT_NFDS;
 	for (i = 0; i < EVENTS_PER_GETN; i++)
 		evpd->ed_pending[i] = -1;

 	evsignal_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)
 {
 	assert(evpd);
 	assert(evpd->ed_nevents > 0);
 	assert(evpd->ed_port > 0);
 	assert(evpd->ed_fds > 0);

 	/*
 	 * Verify the integrity of the fd_info struct as well as the events to
 	 * which it points (at least, that they're valid references and correct
 	 * for their position in the structure).
 	 */
 	int i;
 	for (i = 0; i < evpd->ed_nevents; ++i) {
 		struct event 	*ev;
 		struct fd_info 	*fdi;

 		fdi = &evpd->ed_fds[i];
 		if ((ev = fdi->fdi_revt) != NULL) {
 			assert(ev->ev_fd == i);
 		}
 		if ((ev = fdi->fdi_wevt) != NULL) {
 			assert(ev->ev_fd == i);
 		}
 	}
 }

 /*
  * 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.
 	 */
 	assert(pevt->portev_source == PORT_SOURCE_FD);
 	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;
 	assert(factor > 1);

 	check_evportop(epdp);

 	tmp = 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, void *arg, struct timeval *tv)
 {
 	int i, res;
 	struct evport_data *epdp = arg;
 	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 = FDI_HAS_READ(fdi) ? fdi->fdi_revt->ev_fd :
 			    fdi->fdi_wevt->ev_fd;
 			reassociate(epdp, fdi, fd);
 			epdp->ed_pending[i] = -1;
 		}
 	}

 	if ((res = port_getn(epdp->ed_port, pevtlist, EVENTS_PER_GETN,
 		    (unsigned int *) &nevents, ts_p)) == -1) {
 		if (errno == EINTR || errno == EAGAIN) {
 			evsignal_process(base);
 			return (0);
 		} else if (errno == ETIME) {
 			if (nevents == 0)
 				return (0);
 		} else {
 			event_warn("port_getn");
 			return (-1);
 		}
 	} else if (base->sig.evsignal_caught) {
 		evsignal_process(base);
 	}

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

 	for (i = 0; i < nevents; ++i) {
 		struct event *ev;
 		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 & POLLIN)
 			res |= EV_READ;
 		if (pevt->portev_events & POLLOUT)
 			res |= EV_WRITE;

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

 		/*
 		 * We now check for each of the possible events (READ
 		 * or WRITE).  Then, we activate the event (which will
 		 * cause its callback to be executed).
 		 */

 		if ((res & EV_READ) && ((ev = fdi->fdi_revt) != NULL)) {
 			event_active(ev, res, 1);
 		}

 		if ((res & EV_WRITE) && ((ev = fdi->fdi_wevt) != NULL)) {
 			event_active(ev, res, 1);
 		}
 	} /* 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(void *arg, struct event *ev)
 {
 	struct evport_data *evpd = arg;
 	struct fd_info *fdi;
 	int factor;

 	check_evportop(evpd);

 	/*
 	 * Delegate, if it's not ours to handle.
 	 */
 	if (ev->ev_events & EV_SIGNAL)
 		return (evsignal_add(ev));

 	/*
 	 * If necessary, grow the file descriptor info table
 	 */

 	factor = 1;
 	while (ev->ev_fd >= factor * evpd->ed_nevents)
 		factor *= 2;

 	if (factor > 1) {
 		if (-1 == grow(evpd, factor)) {
 			return (-1);
 		}
 	}

 	fdi = &evpd->ed_fds[ev->ev_fd];
 	if (ev->ev_events & EV_READ)
 		fdi->fdi_revt = ev;
 	if (ev->ev_events & EV_WRITE)
 		fdi->fdi_wevt = ev;

 	return reassociate(evpd, fdi, ev->ev_fd);
 }

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

 static int
 evport_del(void *arg, struct event *ev)
 {
 	struct evport_data *evpd = arg;
 	struct fd_info *fdi;
 	int i;
 	int associated = 1;

 	check_evportop(evpd);

 	/*
 	 * Delegate, if it's not ours to handle
 	 */
 	if (ev->ev_events & EV_SIGNAL) {
 		return (evsignal_del(ev));
 	}

 	if (evpd->ed_nevents < ev->ev_fd) {
 		return (-1);
 	}

 	for (i = 0; i < EVENTS_PER_GETN; ++i) {
 		if (evpd->ed_pending[i] == ev->ev_fd) {
 			associated = 0;
 			break;
 		}
 	}

 	fdi = &evpd->ed_fds[ev->ev_fd];
 	if (ev->ev_events & EV_READ)
 		fdi->fdi_revt = NULL;
 	if (ev->ev_events & EV_WRITE)
 		fdi->fdi_wevt = NULL;

 	if (associated) {
 		if (!FDI_HAS_EVENTS(fdi) &&
 		    port_dissociate(evpd->ed_port, PORT_SOURCE_FD,
 		    ev->ev_fd) == -1) {
 			/*
 			 * Ignre 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, ev->ev_fd));
 			}
 		}
 	} else {
 		if (fdi->fdi_revt == NULL && fdi->fdi_wevt == NULL) {
 			evpd->ed_pending[i] = -1;
 		}
 	}
 	return 0;
 }


 static void
 evport_dealloc(struct event_base *base, void *arg)
 {
 	struct evport_data *evpd = arg;

 	evsignal_dealloc(base);

 	close(evpd->ed_port);

 	if (evpd->ed_fds)
 		free(evpd->ed_fds);
 	free(evpd);
 }
	/*
	* Submitted by David Pacheco (dp.spambait@gmail.com)
	*
	* 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.
	*/

	#ifdef HAVE_CONFIG_H
	#include "config.h"
	#endif

	#include <sys/time.h>
	#include <assert.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>
	#ifdef CHECK_INVARIANTS
	#include <assert.h>
	#endif

	#include "event.h"
	#include "event-internal.h"
	#include "log.h"
	#include "evsignal.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 {
	struct event* fdi_revt; /* the event responsible for the "read" */
	struct event* fdi_wevt; /* the event responsible for the "write" */
	};

	#define FDI_HAS_READ(fdi) ((fdi)->fdi_revt != NULL)
	#define FDI_HAS_WRITE(fdi) ((fdi)->fdi_wevt != NULL)
	#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 (void , struct event );
	static int evport_del (void , struct event );
	static int evport_dispatch (struct event_base , void , struct timeval *);
	static void evport_dealloc (struct event_base , void );

	const struct eventop evportops = {
	"evport",
	evport_init,
	evport_add,
	evport_del,
	evport_dispatch,
	evport_dealloc,
	1 /* need reinit */
	};

	/*
	* Initialize the event port implementation.
	*/

	static void*
	evport_init(struct event_base *base)
	{
	struct evport_data *evpd;
	int i;
	/*
	* Disable event ports when this environment variable is set
	*/
	if (evutil_getenv("EVENT_NOEVPORT"))
	return (NULL);

	if (!(evpd = calloc(1, sizeof(struct evport_data))))
	return (NULL);

	if ((evpd->ed_port = port_create()) == -1) {
	free(evpd);
	return (NULL);
	}

	/*
	* Initialize file descriptor structure
	*/
	evpd->ed_fds = calloc(DEFAULT_NFDS, sizeof(struct fd_info));
	if (evpd->ed_fds == NULL) {
	close(evpd->ed_port);
	free(evpd);
	return (NULL);
	}
	evpd->ed_nevents = DEFAULT_NFDS;
	for (i = 0; i < EVENTS_PER_GETN; i++)
	evpd->ed_pending[i] = -1;

	evsignal_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)
	{
	assert(evpd);
	assert(evpd->ed_nevents > 0);
	assert(evpd->ed_port > 0);
	assert(evpd->ed_fds > 0);

	/*
	* Verify the integrity of the fd_info struct as well as the events to
	* which it points (at least, that they're valid references and correct
	* for their position in the structure).
	*/
	int i;
	for (i = 0; i < evpd->ed_nevents; ++i) {
	struct event *ev;
	struct fd_info *fdi;

	fdi = &evpd->ed_fds[i];
	if ((ev = fdi->fdi_revt) != NULL) {
	assert(ev->ev_fd == i);
	}
	if ((ev = fdi->fdi_wevt) != NULL) {
	assert(ev->ev_fd == i);
	}
	}
	}

	/*
	* 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.
	*/
	assert(pevt->portev_source == PORT_SOURCE_FD);
	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;
	assert(factor > 1);

	check_evportop(epdp);

	tmp = 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, void arg, struct timeval *tv)
	{
	int i, res;
	struct evport_data *epdp = arg;
	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 = FDI_HAS_READ(fdi) ? fdi->fdi_revt->ev_fd :
	fdi->fdi_wevt->ev_fd;
	reassociate(epdp, fdi, fd);
	epdp->ed_pending[i] = -1;
	}
	}

	if ((res = port_getn(epdp->ed_port, pevtlist, EVENTS_PER_GETN,
	(unsigned int *) &nevents, ts_p)) == -1) {
	if (errno == EINTR \|\| errno == EAGAIN) {
	evsignal_process(base);
	return (0);
	} else if (errno == ETIME) {
	if (nevents == 0)
	return (0);
	} else {
	event_warn("port_getn");
	return (-1);
	}
	} else if (base->sig.evsignal_caught) {
	evsignal_process(base);
	}

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

	for (i = 0; i < nevents; ++i) {
	struct event *ev;
	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 & POLLIN)
	res \|= EV_READ;
	if (pevt->portev_events & POLLOUT)
	res \|= EV_WRITE;

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

	/*
	* We now check for each of the possible events (READ
	* or WRITE). Then, we activate the event (which will
	* cause its callback to be executed).
	*/

	if ((res & EV_READ) && ((ev = fdi->fdi_revt) != NULL)) {
	event_active(ev, res, 1);
	}

	if ((res & EV_WRITE) && ((ev = fdi->fdi_wevt) != NULL)) {
	event_active(ev, res, 1);
	}
	} /* 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(void arg, struct event ev)
	{
	struct evport_data *evpd = arg;
	struct fd_info *fdi;
	int factor;

	check_evportop(evpd);

	/*
	* Delegate, if it's not ours to handle.
	*/
	if (ev->ev_events & EV_SIGNAL)
	return (evsignal_add(ev));

	/*
	* If necessary, grow the file descriptor info table
	*/

	factor = 1;
	while (ev->ev_fd >= factor * evpd->ed_nevents)
	factor *= 2;

	if (factor > 1) {
	if (-1 == grow(evpd, factor)) {
	return (-1);
	}
	}

	fdi = &evpd->ed_fds[ev->ev_fd];
	if (ev->ev_events & EV_READ)
	fdi->fdi_revt = ev;
	if (ev->ev_events & EV_WRITE)
	fdi->fdi_wevt = ev;

	return reassociate(evpd, fdi, ev->ev_fd);
	}

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

	static int
	evport_del(void arg, struct event ev)
	{
	struct evport_data *evpd = arg;
	struct fd_info *fdi;
	int i;
	int associated = 1;

	check_evportop(evpd);

	/*
	* Delegate, if it's not ours to handle
	*/
	if (ev->ev_events & EV_SIGNAL) {
	return (evsignal_del(ev));
	}

	if (evpd->ed_nevents < ev->ev_fd) {
	return (-1);
	}

	for (i = 0; i < EVENTS_PER_GETN; ++i) {
	if (evpd->ed_pending[i] == ev->ev_fd) {
	associated = 0;
	break;
	}
	}

	fdi = &evpd->ed_fds[ev->ev_fd];
	if (ev->ev_events & EV_READ)
	fdi->fdi_revt = NULL;
	if (ev->ev_events & EV_WRITE)
	fdi->fdi_wevt = NULL;

	if (associated) {
	if (!FDI_HAS_EVENTS(fdi) &&
	port_dissociate(evpd->ed_port, PORT_SOURCE_FD,
	ev->ev_fd) == -1) {
	/*
	* Ignre 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, ev->ev_fd));
	}
	}
	} else {
	if (fdi->fdi_revt == NULL && fdi->fdi_wevt == NULL) {
	evpd->ed_pending[i] = -1;
	}
	}
	return 0;
	}


	static void
	evport_dealloc(struct event_base base, void arg)
	{
	struct evport_data *evpd = arg;

	evsignal_dealloc(base);

	close(evpd->ed_port);

	if (evpd->ed_fds)
	free(evpd->ed_fds);
	free(evpd);
	}