482 lines
12 KiB
C
482 lines
12 KiB
C
/* $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 _WIN32
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#define WIN32_LEAN_AND_MEAN
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#include <winsock2.h>
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#include <windows.h>
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#undef WIN32_LEAN_AND_MEAN
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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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#include <sys/queue.h>
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#ifdef EVENT__HAVE_SYS_SOCKET_H
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#include <sys/socket.h>
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#endif
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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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#ifdef EVENT__HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <errno.h>
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#ifdef EVENT__HAVE_FCNTL_H
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#include <fcntl.h>
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#endif
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#include "event2/event.h"
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#include "event2/event_struct.h"
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#include "event-internal.h"
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#include "event2/util.h"
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#include "evsignal-internal.h"
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#include "log-internal.h"
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#include "evmap-internal.h"
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#include "evthread-internal.h"
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/*
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signal.c
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This is the signal-handling implementation we use for backends that don't
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have a better way to do signal handling. It uses sigaction() or signal()
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to set a signal handler, and a socket pair to tell the event base when
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Note that I said "the event base" : only one event base can be set up to use
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this at a time. For historical reasons and backward compatibility, if you
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add an event for a signal to event_base A, then add an event for a signal
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(any signal!) to event_base B, event_base B will get informed about the
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signal, but event_base A won't.
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It would be neat to change this behavior in some future version of Libevent.
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kqueue already does something far more sensible. We can make all backends
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on Linux do a reasonable thing using signalfd.
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*/
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#ifndef _WIN32
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/* Windows wants us to call our signal handlers as __cdecl. Nobody else
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* expects you to do anything crazy like this. */
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#ifndef __cdecl
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#define __cdecl
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#endif
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#endif
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static int evsig_add(struct event_base *, evutil_socket_t, short, short, void *);
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static int evsig_del(struct event_base *, evutil_socket_t, short, short, void *);
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static const struct eventop evsigops = {
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"signal",
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NULL,
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evsig_add,
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evsig_del,
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NULL,
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NULL,
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0, 0, 0
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};
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#ifndef EVENT__DISABLE_THREAD_SUPPORT
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/* Lock for evsig_base and evsig_base_n_signals_added fields. */
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static void *evsig_base_lock = NULL;
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#endif
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/* The event base that's currently getting informed about signals. */
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static struct event_base *evsig_base = NULL;
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/* A copy of evsig_base->sigev_n_signals_added. */
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static int evsig_base_n_signals_added = 0;
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static evutil_socket_t evsig_base_fd = -1;
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static void __cdecl evsig_handler(int sig);
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#define EVSIGBASE_LOCK() EVLOCK_LOCK(evsig_base_lock, 0)
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#define EVSIGBASE_UNLOCK() EVLOCK_UNLOCK(evsig_base_lock, 0)
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void
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evsig_set_base_(struct event_base *base)
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{
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EVSIGBASE_LOCK();
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evsig_base = base;
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evsig_base_n_signals_added = base->sig.ev_n_signals_added;
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evsig_base_fd = base->sig.ev_signal_pair[1];
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EVSIGBASE_UNLOCK();
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}
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/* Callback for when the signal handler write a byte to our signaling socket */
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static void
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evsig_cb(evutil_socket_t fd, short what, void *arg)
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{
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static char signals[1024];
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ev_ssize_t n;
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int i;
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int ncaught[NSIG];
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struct event_base *base;
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base = arg;
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memset(&ncaught, 0, sizeof(ncaught));
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while (1) {
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#ifdef _WIN32
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n = recv(fd, signals, sizeof(signals), 0);
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#else
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n = read(fd, signals, sizeof(signals));
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#endif
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if (n == -1) {
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int err = evutil_socket_geterror(fd);
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if (! EVUTIL_ERR_RW_RETRIABLE(err))
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event_sock_err(1, fd, "%s: recv", __func__);
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break;
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} else if (n == 0) {
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/* XXX warn? */
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break;
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}
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for (i = 0; i < n; ++i) {
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ev_uint8_t sig = signals[i];
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if (sig < NSIG)
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ncaught[sig]++;
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}
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}
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EVBASE_ACQUIRE_LOCK(base, th_base_lock);
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for (i = 0; i < NSIG; ++i) {
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if (ncaught[i])
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evmap_signal_active_(base, i, ncaught[i]);
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}
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EVBASE_RELEASE_LOCK(base, th_base_lock);
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}
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int
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evsig_init_(struct event_base *base)
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{
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/*
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* Our signal handler is going to write to one end of the socket
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* pair to wake up our event loop. The event loop then scans for
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* signals that got delivered.
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*/
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if (evutil_make_internal_pipe_(base->sig.ev_signal_pair) == -1) {
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#ifdef _WIN32
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/* Make this nonfatal on win32, where sometimes people
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have localhost firewalled. */
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event_sock_warn(-1, "%s: socketpair", __func__);
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#else
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event_sock_err(1, -1, "%s: socketpair", __func__);
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#endif
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return -1;
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}
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if (base->sig.sh_old) {
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mm_free(base->sig.sh_old);
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}
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base->sig.sh_old = NULL;
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base->sig.sh_old_max = 0;
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event_assign(&base->sig.ev_signal, base, base->sig.ev_signal_pair[0],
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EV_READ | EV_PERSIST, evsig_cb, base);
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base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL;
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event_priority_set(&base->sig.ev_signal, 0);
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base->evsigsel = &evsigops;
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return 0;
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}
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/* Helper: set the signal handler for evsignal to handler in base, so that
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* we can restore the original handler when we clear the current one. */
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int
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evsig_set_handler_(struct event_base *base,
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int evsignal, void (__cdecl *handler)(int))
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{
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#ifdef EVENT__HAVE_SIGACTION
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struct sigaction sa;
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#else
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ev_sighandler_t sh;
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#endif
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struct evsig_info *sig = &base->sig;
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void *p;
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/*
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* resize saved signal handler array up to the highest signal number.
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* a dynamic array is used to keep footprint on the low side.
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*/
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if (evsignal >= sig->sh_old_max) {
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int new_max = evsignal + 1;
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event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",
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__func__, evsignal, sig->sh_old_max));
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p = mm_realloc(sig->sh_old, new_max * sizeof(*sig->sh_old));
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if (p == NULL) {
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event_warn("realloc");
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return (-1);
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}
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memset((char *)p + sig->sh_old_max * sizeof(*sig->sh_old),
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0, (new_max - sig->sh_old_max) * sizeof(*sig->sh_old));
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sig->sh_old_max = new_max;
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sig->sh_old = p;
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}
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/* allocate space for previous handler out of dynamic array */
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sig->sh_old[evsignal] = mm_malloc(sizeof *sig->sh_old[evsignal]);
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if (sig->sh_old[evsignal] == NULL) {
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event_warn("malloc");
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return (-1);
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}
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/* save previous handler and setup new handler */
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#ifdef EVENT__HAVE_SIGACTION
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memset(&sa, 0, sizeof(sa));
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sa.sa_handler = handler;
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sa.sa_flags |= SA_RESTART;
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sigfillset(&sa.sa_mask);
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if (sigaction(evsignal, &sa, sig->sh_old[evsignal]) == -1) {
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event_warn("sigaction");
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mm_free(sig->sh_old[evsignal]);
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sig->sh_old[evsignal] = NULL;
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return (-1);
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}
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#else
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if ((sh = signal(evsignal, handler)) == SIG_ERR) {
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event_warn("signal");
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mm_free(sig->sh_old[evsignal]);
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sig->sh_old[evsignal] = NULL;
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return (-1);
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}
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*sig->sh_old[evsignal] = sh;
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#endif
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return (0);
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}
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static int
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evsig_add(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
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{
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struct evsig_info *sig = &base->sig;
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(void)p;
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EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
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/* catch signals if they happen quickly */
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EVSIGBASE_LOCK();
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if (evsig_base != base && evsig_base_n_signals_added) {
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event_warnx("Added a signal to event base %p with signals "
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"already added to event_base %p. Only one can have "
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"signals at a time with the %s backend. The base with "
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"the most recently added signal or the most recent "
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"event_base_loop() call gets preference; do "
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"not rely on this behavior in future Libevent versions.",
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base, evsig_base, base->evsel->name);
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}
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evsig_base = base;
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evsig_base_n_signals_added = ++sig->ev_n_signals_added;
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evsig_base_fd = base->sig.ev_signal_pair[1];
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EVSIGBASE_UNLOCK();
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event_debug(("%s: %d: changing signal handler", __func__, (int)evsignal));
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if (evsig_set_handler_(base, (int)evsignal, evsig_handler) == -1) {
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goto err;
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}
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if (!sig->ev_signal_added) {
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if (event_add_nolock_(&sig->ev_signal, NULL, 0))
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goto err;
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sig->ev_signal_added = 1;
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}
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return (0);
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err:
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EVSIGBASE_LOCK();
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--evsig_base_n_signals_added;
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--sig->ev_n_signals_added;
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EVSIGBASE_UNLOCK();
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return (-1);
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}
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int
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evsig_restore_handler_(struct event_base *base, int evsignal)
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{
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int ret = 0;
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struct evsig_info *sig = &base->sig;
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#ifdef EVENT__HAVE_SIGACTION
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struct sigaction *sh;
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#else
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ev_sighandler_t *sh;
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#endif
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if (evsignal >= sig->sh_old_max) {
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/* Can't actually restore. */
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/* XXXX.*/
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return 0;
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}
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/* restore previous handler */
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sh = sig->sh_old[evsignal];
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sig->sh_old[evsignal] = NULL;
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#ifdef EVENT__HAVE_SIGACTION
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if (sigaction(evsignal, sh, NULL) == -1) {
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event_warn("sigaction");
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ret = -1;
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}
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#else
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if (signal(evsignal, *sh) == SIG_ERR) {
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event_warn("signal");
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ret = -1;
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}
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#endif
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mm_free(sh);
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return ret;
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}
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static int
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evsig_del(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
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{
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EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
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event_debug(("%s: "EV_SOCK_FMT": restoring signal handler",
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__func__, EV_SOCK_ARG(evsignal)));
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EVSIGBASE_LOCK();
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--evsig_base_n_signals_added;
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--base->sig.ev_n_signals_added;
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EVSIGBASE_UNLOCK();
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return (evsig_restore_handler_(base, (int)evsignal));
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}
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static void __cdecl
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evsig_handler(int sig)
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{
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int save_errno = errno;
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#ifdef _WIN32
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int socket_errno = EVUTIL_SOCKET_ERROR();
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#endif
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ev_uint8_t msg;
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if (evsig_base == NULL) {
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event_warnx(
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"%s: received signal %d, but have no base configured",
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__func__, sig);
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return;
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}
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#ifndef EVENT__HAVE_SIGACTION
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signal(sig, evsig_handler);
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#endif
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/* Wake up our notification mechanism */
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msg = sig;
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#ifdef _WIN32
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send(evsig_base_fd, (char*)&msg, 1, 0);
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#else
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{
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int r = write(evsig_base_fd, (char*)&msg, 1);
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(void)r; /* Suppress 'unused return value' and 'unused var' */
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}
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#endif
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errno = save_errno;
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#ifdef _WIN32
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EVUTIL_SET_SOCKET_ERROR(socket_errno);
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#endif
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}
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void
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evsig_dealloc_(struct event_base *base)
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{
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int i = 0;
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if (base->sig.ev_signal_added) {
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event_del(&base->sig.ev_signal);
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base->sig.ev_signal_added = 0;
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}
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/* debug event is created in evsig_init_/event_assign even when
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* ev_signal_added == 0, so unassign is required */
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event_debug_unassign(&base->sig.ev_signal);
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for (i = 0; i < NSIG; ++i) {
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if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
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evsig_restore_handler_(base, i);
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}
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EVSIGBASE_LOCK();
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if (base == evsig_base) {
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evsig_base = NULL;
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evsig_base_n_signals_added = 0;
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evsig_base_fd = -1;
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}
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EVSIGBASE_UNLOCK();
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if (base->sig.ev_signal_pair[0] != -1) {
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evutil_closesocket(base->sig.ev_signal_pair[0]);
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base->sig.ev_signal_pair[0] = -1;
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}
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if (base->sig.ev_signal_pair[1] != -1) {
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evutil_closesocket(base->sig.ev_signal_pair[1]);
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base->sig.ev_signal_pair[1] = -1;
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}
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base->sig.sh_old_max = 0;
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/* per index frees are handled in evsig_del() */
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if (base->sig.sh_old) {
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mm_free(base->sig.sh_old);
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base->sig.sh_old = NULL;
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}
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}
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static void
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evsig_free_globals_locks(void)
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{
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#ifndef EVENT__DISABLE_THREAD_SUPPORT
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if (evsig_base_lock != NULL) {
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EVTHREAD_FREE_LOCK(evsig_base_lock, 0);
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evsig_base_lock = NULL;
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}
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#endif
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return;
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}
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void
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evsig_free_globals_(void)
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{
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evsig_free_globals_locks();
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}
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#ifndef EVENT__DISABLE_THREAD_SUPPORT
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int
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evsig_global_setup_locks_(const int enable_locks)
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{
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EVTHREAD_SETUP_GLOBAL_LOCK(evsig_base_lock, 0);
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return 0;
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}
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#endif
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