347 lines
8.5 KiB
C
347 lines
8.5 KiB
C
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/* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
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/*
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* Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
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* Copyright 2007-2012 Niels Provos and Nick Mathewson
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "event2/event-config.h"
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#include "evconfig-private.h"
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#ifdef EVENT__HAVE_SELECT
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#ifdef __APPLE__
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/* Apple wants us to define this if we might ever pass more than
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* FD_SETSIZE bits to select(). */
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#define _DARWIN_UNLIMITED_SELECT
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#endif
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#include <sys/types.h>
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#ifdef EVENT__HAVE_SYS_TIME_H
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#include <sys/time.h>
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#endif
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#ifdef EVENT__HAVE_SYS_SELECT_H
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#include <sys/select.h>
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#endif
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#include <sys/queue.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include "event-internal.h"
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#include "evsignal-internal.h"
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#include "event2/thread.h"
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#include "evthread-internal.h"
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#include "log-internal.h"
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#include "evmap-internal.h"
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#ifndef EVENT__HAVE_FD_MASK
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/* This type is mandatory, but Android doesn't define it. */
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typedef unsigned long fd_mask;
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#endif
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#ifndef NFDBITS
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#define NFDBITS (sizeof(fd_mask)*8)
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#endif
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/* Divide positive x by y, rounding up. */
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#define DIV_ROUNDUP(x, y) (((x)+((y)-1))/(y))
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/* How many bytes to allocate for N fds? */
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#define SELECT_ALLOC_SIZE(n) \
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(DIV_ROUNDUP(n, NFDBITS) * sizeof(fd_mask))
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struct selectop {
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int event_fds; /* Highest fd in fd set */
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int event_fdsz;
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int resize_out_sets;
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fd_set *event_readset_in;
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fd_set *event_writeset_in;
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fd_set *event_readset_out;
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fd_set *event_writeset_out;
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};
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static void *select_init(struct event_base *);
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static int select_add(struct event_base *, int, short old, short events, void*);
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static int select_del(struct event_base *, int, short old, short events, void*);
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static int select_dispatch(struct event_base *, struct timeval *);
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static void select_dealloc(struct event_base *);
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const struct eventop selectops = {
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"select",
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select_init,
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select_add,
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select_del,
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select_dispatch,
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select_dealloc,
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0, /* doesn't need reinit. */
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EV_FEATURE_FDS,
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0,
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};
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static int select_resize(struct selectop *sop, int fdsz);
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static void select_free_selectop(struct selectop *sop);
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static void *
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select_init(struct event_base *base)
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{
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struct selectop *sop;
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if (!(sop = mm_calloc(1, sizeof(struct selectop))))
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return (NULL);
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if (select_resize(sop, SELECT_ALLOC_SIZE(32 + 1))) {
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select_free_selectop(sop);
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return (NULL);
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}
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evsig_init_(base);
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evutil_weakrand_seed_(&base->weakrand_seed, 0);
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return (sop);
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}
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#ifdef CHECK_INVARIANTS
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static void
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check_selectop(struct selectop *sop)
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{
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/* nothing to be done here */
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}
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#else
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#define check_selectop(sop) do { (void) sop; } while (0)
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#endif
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static int
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select_dispatch(struct event_base *base, struct timeval *tv)
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{
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int res=0, i, j, nfds;
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struct selectop *sop = base->evbase;
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check_selectop(sop);
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if (sop->resize_out_sets) {
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fd_set *readset_out=NULL, *writeset_out=NULL;
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size_t sz = sop->event_fdsz;
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if (!(readset_out = mm_realloc(sop->event_readset_out, sz)))
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return (-1);
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sop->event_readset_out = readset_out;
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if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) {
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/* We don't free readset_out here, since it was
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* already successfully reallocated. The next time
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* we call select_dispatch, the realloc will be a
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* no-op. */
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return (-1);
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}
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sop->event_writeset_out = writeset_out;
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sop->resize_out_sets = 0;
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}
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memcpy(sop->event_readset_out, sop->event_readset_in,
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sop->event_fdsz);
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memcpy(sop->event_writeset_out, sop->event_writeset_in,
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sop->event_fdsz);
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nfds = sop->event_fds+1;
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EVBASE_RELEASE_LOCK(base, th_base_lock);
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res = select(nfds, sop->event_readset_out,
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sop->event_writeset_out, NULL, tv);
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EVBASE_ACQUIRE_LOCK(base, th_base_lock);
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check_selectop(sop);
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if (res == -1) {
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if (errno != EINTR) {
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event_warn("select");
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return (-1);
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}
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return (0);
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}
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event_debug(("%s: select reports %d", __func__, res));
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check_selectop(sop);
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i = evutil_weakrand_range_(&base->weakrand_seed, nfds);
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for (j = 0; j < nfds; ++j) {
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if (++i >= nfds)
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i = 0;
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res = 0;
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if (FD_ISSET(i, sop->event_readset_out))
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res |= EV_READ;
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if (FD_ISSET(i, sop->event_writeset_out))
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res |= EV_WRITE;
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if (res == 0)
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continue;
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evmap_io_active_(base, i, res);
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}
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check_selectop(sop);
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return (0);
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}
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static int
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select_resize(struct selectop *sop, int fdsz)
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{
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fd_set *readset_in = NULL;
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fd_set *writeset_in = NULL;
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if (sop->event_readset_in)
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check_selectop(sop);
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if ((readset_in = mm_realloc(sop->event_readset_in, fdsz)) == NULL)
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goto error;
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sop->event_readset_in = readset_in;
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if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL) {
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/* Note that this will leave event_readset_in expanded.
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* That's okay; we wouldn't want to free it, since that would
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* change the semantics of select_resize from "expand the
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* readset_in and writeset_in, or return -1" to "expand the
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* *set_in members, or trash them and return -1."
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*/
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goto error;
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}
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sop->event_writeset_in = writeset_in;
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sop->resize_out_sets = 1;
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memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
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fdsz - sop->event_fdsz);
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memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
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fdsz - sop->event_fdsz);
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sop->event_fdsz = fdsz;
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check_selectop(sop);
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return (0);
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error:
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event_warn("malloc");
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return (-1);
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}
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static int
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select_add(struct event_base *base, int fd, short old, short events, void *p)
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{
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struct selectop *sop = base->evbase;
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(void) p;
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EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
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check_selectop(sop);
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/*
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* Keep track of the highest fd, so that we can calculate the size
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* of the fd_sets for select(2)
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*/
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if (sop->event_fds < fd) {
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int fdsz = sop->event_fdsz;
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if (fdsz < (int)sizeof(fd_mask))
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fdsz = (int)sizeof(fd_mask);
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/* In theory we should worry about overflow here. In
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* reality, though, the highest fd on a unixy system will
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* not overflow here. XXXX */
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while (fdsz < (int) SELECT_ALLOC_SIZE(fd + 1))
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fdsz *= 2;
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if (fdsz != sop->event_fdsz) {
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if (select_resize(sop, fdsz)) {
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check_selectop(sop);
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return (-1);
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}
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}
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sop->event_fds = fd;
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}
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if (events & EV_READ)
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FD_SET(fd, sop->event_readset_in);
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if (events & EV_WRITE)
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FD_SET(fd, sop->event_writeset_in);
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check_selectop(sop);
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return (0);
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}
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/*
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* Nothing to be done here.
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*/
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static int
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select_del(struct event_base *base, int fd, short old, short events, void *p)
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{
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struct selectop *sop = base->evbase;
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(void)p;
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EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
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check_selectop(sop);
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if (sop->event_fds < fd) {
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check_selectop(sop);
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return (0);
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}
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if (events & EV_READ)
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FD_CLR(fd, sop->event_readset_in);
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if (events & EV_WRITE)
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FD_CLR(fd, sop->event_writeset_in);
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check_selectop(sop);
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return (0);
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}
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static void
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select_free_selectop(struct selectop *sop)
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{
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if (sop->event_readset_in)
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mm_free(sop->event_readset_in);
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if (sop->event_writeset_in)
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mm_free(sop->event_writeset_in);
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if (sop->event_readset_out)
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mm_free(sop->event_readset_out);
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if (sop->event_writeset_out)
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mm_free(sop->event_writeset_out);
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memset(sop, 0, sizeof(struct selectop));
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mm_free(sop);
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}
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static void
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select_dealloc(struct event_base *base)
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{
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evsig_dealloc_(base);
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select_free_selectop(base->evbase);
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}
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#endif /* EVENT__HAVE_SELECT */
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