The Tor Browser / file revision

 /*	$OpenBSD: select.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

 #ifdef _EVENT_HAVE_SYS_SELECT_H

 #include <sys/select.h>

 #endif

 #include <sys/queue.h>

 #include <signal.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 "event2/thread.h"

 #include "evthread-internal.h"

 #include "log-internal.h"

 #include "evmap-internal.h"

 #ifndef _EVENT_HAVE_FD_MASK

 /* This type is mandatory, but Android doesn't define it. */

 typedef unsigned long fd_mask;

 #endif

 #ifndef NFDBITS

 #define NFDBITS (sizeof(fd_mask)*8)

 #endif

 /* Divide positive x by y, rounding up. */

 #define DIV_ROUNDUP(x, y)   (((x)+((y)-1))/(y))

 /* How many bytes to allocate for N fds? */

 #define SELECT_ALLOC_SIZE(n) \

 	(DIV_ROUNDUP(n, NFDBITS) * sizeof(fd_mask))

 struct selectop {

 	int event_fds;		/* Highest fd in fd set */

 	int event_fdsz;

 	int resize_out_sets;

 	fd_set *event_readset_in;

 	fd_set *event_writeset_in;

 	fd_set *event_readset_out;

 	fd_set *event_writeset_out;

 };

 static void *select_init(struct event_base *);

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

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

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

 static void select_dealloc(struct event_base *);

 const struct eventop selectops = {

 	"select",

 	select_init,

 	select_add,

 	select_del,

 	select_dispatch,

 	select_dealloc,

 	0, /* doesn't need reinit. */

 	EV_FEATURE_FDS,

 	0,

 };

 static int select_resize(struct selectop *sop, int fdsz);

 static void select_free_selectop(struct selectop *sop);

 static void *

 select_init(struct event_base *base)

 {

 	struct selectop *sop;

 	if (!(sop = mm_calloc(1, sizeof(struct selectop))))

 		return (NULL);

 	if (select_resize(sop, SELECT_ALLOC_SIZE(32 + 1))) {

 		select_free_selectop(sop);

 		return (NULL);

 	}

 	evsig_init(base);

 	return (sop);

 }

 #ifdef CHECK_INVARIANTS

 static void

 check_selectop(struct selectop *sop)

 {

 	/* nothing to be done here */

 }

 #else

 #define check_selectop(sop) do { (void) sop; } while (0)

 #endif

 static int

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

 {

 	int res=0, i, j, nfds;

 	struct selectop *sop = base->evbase;

 	check_selectop(sop);

 	if (sop->resize_out_sets) {

 		fd_set *readset_out=NULL, *writeset_out=NULL;

 		size_t sz = sop->event_fdsz;

 		if (!(readset_out = mm_realloc(sop->event_readset_out, sz)))

 			return (-1);

 		sop->event_readset_out = readset_out;

 		if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) {

 			/* We don't free readset_out here, since it was

 			 * already successfully reallocated. The next time

 			 * we call select_dispatch, the realloc will be a

 			 * no-op. */

 			return (-1);

 		}

 		sop->event_writeset_out = writeset_out;

 		sop->resize_out_sets = 0;

 	}

 	memcpy(sop->event_readset_out, sop->event_readset_in,

 	       sop->event_fdsz);

 	memcpy(sop->event_writeset_out, sop->event_writeset_in,

 	       sop->event_fdsz);

 	nfds = sop->event_fds+1;

 	EVBASE_RELEASE_LOCK(base, th_base_lock);

 	res = select(nfds, sop->event_readset_out,

 	    sop->event_writeset_out, NULL, tv);

 	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

 	check_selectop(sop);

 	if (res == -1) {

 		if (errno != EINTR) {

 			event_warn("select");

 			return (-1);

 		}

 		return (0);

 	}

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

 	check_selectop(sop);

 	i = random() % nfds;

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

 		if (++i >= nfds)

 			i = 0;

 		res = 0;

 		if (FD_ISSET(i, sop->event_readset_out))

 			res |= EV_READ;

 		if (FD_ISSET(i, sop->event_writeset_out))

 			res |= EV_WRITE;

 		if (res == 0)

 			continue;

 		evmap_io_active(base, i, res);

 	}

 	check_selectop(sop);

 	return (0);

 }

 static int

 select_resize(struct selectop *sop, int fdsz)

 {

 	fd_set *readset_in = NULL;

 	fd_set *writeset_in = NULL;

 	if (sop->event_readset_in)

 		check_selectop(sop);

 	if ((readset_in = mm_realloc(sop->event_readset_in, fdsz)) == NULL)

 		goto error;

 	sop->event_readset_in = readset_in;

 	if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL) {

 		/* Note that this will leave event_readset_in expanded.

 		 * That's okay; we wouldn't want to free it, since that would

 		 * change the semantics of select_resize from "expand the

 		 * readset_in and writeset_in, or return -1" to "expand the

 		 * *set_in members, or trash them and return -1."

 		 */

 		goto error;

 	}

 	sop->event_writeset_in = writeset_in;

 	sop->resize_out_sets = 1;

 	memset((char *)sop->event_readset_in + sop->event_fdsz, 0,

 	    fdsz - sop->event_fdsz);

 	memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,

 	    fdsz - sop->event_fdsz);

 	sop->event_fdsz = fdsz;

 	check_selectop(sop);

 	return (0);

  error:

 	event_warn("malloc");

 	return (-1);

 }

 static int

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

 {

 	struct selectop *sop = base->evbase;

 	(void) p;

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

 	check_selectop(sop);

 	/*

 	 * Keep track of the highest fd, so that we can calculate the size

 	 * of the fd_sets for select(2)

 	 */

 	if (sop->event_fds < fd) {

 		int fdsz = sop->event_fdsz;

 		if (fdsz < (int)sizeof(fd_mask))

 			fdsz = (int)sizeof(fd_mask);

 		/* In theory we should worry about overflow here.  In

 		 * reality, though, the highest fd on a unixy system will

 		 * not overflow here. XXXX */

 		while (fdsz < (int) SELECT_ALLOC_SIZE(fd + 1))

 			fdsz *= 2;

 		if (fdsz != sop->event_fdsz) {

 			if (select_resize(sop, fdsz)) {

 				check_selectop(sop);

 				return (-1);

 			}

 		}

 		sop->event_fds = fd;

 	}

 	if (events & EV_READ)

 		FD_SET(fd, sop->event_readset_in);

 	if (events & EV_WRITE)

 		FD_SET(fd, sop->event_writeset_in);

 	check_selectop(sop);

 	return (0);

 }

 /*

  * Nothing to be done here.

  */

 static int

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

 {

 	struct selectop *sop = base->evbase;

 	(void)p;

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

 	check_selectop(sop);

 	if (sop->event_fds < fd) {

 		check_selectop(sop);

 		return (0);

 	}

 	if (events & EV_READ)

 		FD_CLR(fd, sop->event_readset_in);

 	if (events & EV_WRITE)

 		FD_CLR(fd, sop->event_writeset_in);

 	check_selectop(sop);

 	return (0);

 }

 static void

 select_free_selectop(struct selectop *sop)

 {

 	if (sop->event_readset_in)

 		mm_free(sop->event_readset_in);

 	if (sop->event_writeset_in)

 		mm_free(sop->event_writeset_in);

 	if (sop->event_readset_out)

 		mm_free(sop->event_readset_out);

 	if (sop->event_writeset_out)

 		mm_free(sop->event_writeset_out);

 	memset(sop, 0, sizeof(struct selectop));

 	mm_free(sop);

 }

 static void

 select_dealloc(struct event_base *base)

 {

 	evsig_dealloc(base);

 	select_free_selectop(base->evbase);

 }