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/* $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 "evconfig-private.h"
#ifdef EVENT__HAVE_SELECT
#ifdef __APPLE__
/* Apple wants us to define this if we might ever pass more than
* FD_SETSIZE bits to select(). */
#define _DARWIN_UNLIMITED_SELECT
#endif
#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,
1, /* 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);
evutil_weakrand_seed_(&base->weakrand_seed, 0);
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 = evutil_weakrand_range_(&base->weakrand_seed, 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);
}
#endif /* EVENT__HAVE_SELECT */