tor-browser

evport.c (12005B)

---

/*
* 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 "evconfig-private.h"

#ifdef EVENT__HAVE_EVENT_PORTS

#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"

#define INITIAL_EVENTS_PER_GETN 8
#define MAX_EVENTS_PER_GETN 4096

/*
* 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 {
/* combinations of EV_READ and EV_WRITE */
short fdi_what;
/* Index of this fd within ed_pending, plus 1.  Zero if this fd is
 * not in ed_pending.  (The +1 is a hack so that memset(0) will set
 * it to a nil index. */
int pending_idx_plus_1;
};

#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  */
/* How many elements of ed_pending should we look at? */
int ed_npending;
/* How many elements are allocated in ed_pending and pevtlist? */
int ed_maxevents;
/* fdi's that we need to reassoc */
int *ed_pending;
/* storage space for incoming events. */ 
port_event_t *ed_pevtlist;

};

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 *);
static int	grow(struct evport_data *, int min_events);

const struct eventop evportops = {
"evport",
evport_init,
evport_add,
evport_del,
evport_dispatch,
evport_dealloc,
1, /* need reinit */
0, /* features */
sizeof(struct fd_info), /* fdinfo length */
};

/*
* Initialize the event port implementation.
*/

static void*
evport_init(struct event_base *base)
{
struct evport_data *evpd;

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

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

if (grow(evpd, INITIAL_EVENTS_PER_GETN) < 0) {
	close(evpd->ed_port);
	mm_free(evpd);
	return NULL;
}
	
evpd->ed_npending = 0;

evsig_init_(base);

return (evpd);
}

static int
grow(struct evport_data *data, int min_events)
{
int newsize;
int *new_pending;
port_event_t *new_pevtlist;
if (data->ed_maxevents) {
	newsize = data->ed_maxevents;
	do {
		newsize *= 2;
	} while (newsize < min_events);
} else {
	newsize = min_events;
}

new_pending = mm_realloc(data->ed_pending, sizeof(int)*newsize);
if (new_pending == NULL)
	return -1;
data->ed_pending = new_pending;
new_pevtlist = mm_realloc(data->ed_pevtlist, sizeof(port_event_t)*newsize);
if (new_pevtlist == NULL)
	return -1;
data->ed_pevtlist = new_pevtlist; 

data->ed_maxevents = newsize;
return 0;
}

#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_port > 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);
}

#else
#define check_evportop(epop)
#define check_event(pevt)
#endif /* CHECK_INVARIANTS */

/*
* (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, fdip) == -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 = epdp->ed_pevtlist;

/*
 * 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 (ed_maxevents)) 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 < epdp->ed_npending; ++i) {
	struct fd_info *fdi = NULL;
	const int fd = epdp->ed_pending[i];
	if (fd != -1) {
		/* We might have cleared out this event; we need
		 * to be sure that it's still set. */
		fdi = evmap_io_get_fdinfo_(&base->io, fd);
	}

	if (fdi != NULL && FDI_HAS_EVENTS(fdi)) {
		reassociate(epdp, fdi, fd);
		/* epdp->ed_pending[i] = -1; */
		fdi->pending_idx_plus_1 = 0;
	}
}

EVBASE_RELEASE_LOCK(base, th_base_lock);

res = port_getn(epdp->ed_port, pevtlist, epdp->ed_maxevents,
    (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) {
	port_event_t *pevt = &pevtlist[i];
	int fd = (int) pevt->portev_object;
	struct fd_info *fdi = pevt->portev_user;
	/*EVUTIL_ASSERT(evmap_io_get_fdinfo_(&base->io, fd) == fdi);*/

	check_evportop(epdp);
	check_event(pevt);
	epdp->ed_pending[i] = fd;
	fdi->pending_idx_plus_1 = i + 1;

	/*
	 * 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;

	evmap_io_active_(base, fd, res);
} /* end of all events gotten */
epdp->ed_npending = nevents;

if (nevents == epdp->ed_maxevents &&
    epdp->ed_maxevents < MAX_EVENTS_PER_GETN) {
	/* we used all the space this time.  We should be ready
	 * for more events next time around. */
	grow(epdp, epdp->ed_maxevents * 2);
}

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 = p;

check_evportop(evpd);

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 = p;
int associated = ! fdi->pending_idx_plus_1;

check_evportop(evpd);

fdi->fdi_what &= ~(events &(EV_READ|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) {
		const int i = fdi->pending_idx_plus_1 - 1;
		EVUTIL_ASSERT(evpd->ed_pending[i] == fd);
		evpd->ed_pending[i] = -1;
		fdi->pending_idx_plus_1 = 0;
	}
}
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_pending)
	mm_free(evpd->ed_pending);
if (evpd->ed_pevtlist)
	mm_free(evpd->ed_pevtlist);

mm_free(evpd);
}

#endif /* EVENT__HAVE_EVENT_PORTS */