michael@0: /*	$OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $	*/
michael@0: 
michael@0: /*
michael@0:  * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
michael@0:  * Copyright 2007-2012 Niels Provos and Nick Mathewson
michael@0:  *
michael@0:  * Redistribution and use in source and binary forms, with or without
michael@0:  * modification, are permitted provided that the following conditions
michael@0:  * are met:
michael@0:  * 1. Redistributions of source code must retain the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer.
michael@0:  * 2. Redistributions in binary form must reproduce the above copyright
michael@0:  *    notice, this list of conditions and the following disclaimer in the
michael@0:  *    documentation and/or other materials provided with the distribution.
michael@0:  * 3. The name of the author may not be used to endorse or promote products
michael@0:  *    derived from this software without specific prior written permission.
michael@0:  *
michael@0:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
michael@0:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
michael@0:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
michael@0:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
michael@0:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
michael@0:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0:  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
michael@0:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0:  */
michael@0: #include "event2/event-config.h"
michael@0: 
michael@0: #ifdef WIN32
michael@0: #define WIN32_LEAN_AND_MEAN
michael@0: #include <winsock2.h>
michael@0: #include <windows.h>
michael@0: #undef WIN32_LEAN_AND_MEAN
michael@0: #endif
michael@0: #include <sys/types.h>
michael@0: #ifdef _EVENT_HAVE_SYS_TIME_H
michael@0: #include <sys/time.h>
michael@0: #endif
michael@0: #include <sys/queue.h>
michael@0: #ifdef _EVENT_HAVE_SYS_SOCKET_H
michael@0: #include <sys/socket.h>
michael@0: #endif
michael@0: #include <signal.h>
michael@0: #include <stdio.h>
michael@0: #include <stdlib.h>
michael@0: #include <string.h>
michael@0: #ifdef _EVENT_HAVE_UNISTD_H
michael@0: #include <unistd.h>
michael@0: #endif
michael@0: #include <errno.h>
michael@0: #ifdef _EVENT_HAVE_FCNTL_H
michael@0: #include <fcntl.h>
michael@0: #endif
michael@0: 
michael@0: #include "event2/event.h"
michael@0: #include "event2/event_struct.h"
michael@0: #include "event-internal.h"
michael@0: #include "event2/util.h"
michael@0: #include "evsignal-internal.h"
michael@0: #include "log-internal.h"
michael@0: #include "evmap-internal.h"
michael@0: #include "evthread-internal.h"
michael@0: 
michael@0: /*
michael@0:   signal.c
michael@0: 
michael@0:   This is the signal-handling implementation we use for backends that don't
michael@0:   have a better way to do signal handling.  It uses sigaction() or signal()
michael@0:   to set a signal handler, and a socket pair to tell the event base when
michael@0: 
michael@0:   Note that I said "the event base" : only one event base can be set up to use
michael@0:   this at a time.  For historical reasons and backward compatibility, if you
michael@0:   add an event for a signal to event_base A, then add an event for a signal
michael@0:   (any signal!) to event_base B, event_base B will get informed about the
michael@0:   signal, but event_base A won't.
michael@0: 
michael@0:   It would be neat to change this behavior in some future version of Libevent.
michael@0:   kqueue already does something far more sensible.  We can make all backends
michael@0:   on Linux do a reasonable thing using signalfd.
michael@0: */
michael@0: 
michael@0: #ifndef WIN32
michael@0: /* Windows wants us to call our signal handlers as __cdecl.  Nobody else
michael@0:  * expects you to do anything crazy like this. */
michael@0: #define __cdecl
michael@0: #endif
michael@0: 
michael@0: static int evsig_add(struct event_base *, evutil_socket_t, short, short, void *);
michael@0: static int evsig_del(struct event_base *, evutil_socket_t, short, short, void *);
michael@0: 
michael@0: static const struct eventop evsigops = {
michael@0: 	"signal",
michael@0: 	NULL,
michael@0: 	evsig_add,
michael@0: 	evsig_del,
michael@0: 	NULL,
michael@0: 	NULL,
michael@0: 	0, 0, 0
michael@0: };
michael@0: 
michael@0: #ifndef _EVENT_DISABLE_THREAD_SUPPORT
michael@0: /* Lock for evsig_base and evsig_base_n_signals_added fields. */
michael@0: static void *evsig_base_lock = NULL;
michael@0: #endif
michael@0: /* The event base that's currently getting informed about signals. */
michael@0: static struct event_base *evsig_base = NULL;
michael@0: /* A copy of evsig_base->sigev_n_signals_added. */
michael@0: static int evsig_base_n_signals_added = 0;
michael@0: static evutil_socket_t evsig_base_fd = -1;
michael@0: 
michael@0: static void __cdecl evsig_handler(int sig);
michael@0: 
michael@0: #define EVSIGBASE_LOCK() EVLOCK_LOCK(evsig_base_lock, 0)
michael@0: #define EVSIGBASE_UNLOCK() EVLOCK_UNLOCK(evsig_base_lock, 0)
michael@0: 
michael@0: void
michael@0: evsig_set_base(struct event_base *base)
michael@0: {
michael@0: 	EVSIGBASE_LOCK();
michael@0: 	evsig_base = base;
michael@0: 	evsig_base_n_signals_added = base->sig.ev_n_signals_added;
michael@0: 	evsig_base_fd = base->sig.ev_signal_pair[0];
michael@0: 	EVSIGBASE_UNLOCK();
michael@0: }
michael@0: 
michael@0: /* Callback for when the signal handler write a byte to our signaling socket */
michael@0: static void
michael@0: evsig_cb(evutil_socket_t fd, short what, void *arg)
michael@0: {
michael@0: 	static char signals[1024];
michael@0: 	ev_ssize_t n;
michael@0: 	int i;
michael@0: 	int ncaught[NSIG];
michael@0: 	struct event_base *base;
michael@0: 
michael@0: 	base = arg;
michael@0: 
michael@0: 	memset(&ncaught, 0, sizeof(ncaught));
michael@0: 
michael@0: 	while (1) {
michael@0: 		n = recv(fd, signals, sizeof(signals), 0);
michael@0: 		if (n == -1) {
michael@0: 			int err = evutil_socket_geterror(fd);
michael@0: 			if (! EVUTIL_ERR_RW_RETRIABLE(err))
michael@0: 				event_sock_err(1, fd, "%s: recv", __func__);
michael@0: 			break;
michael@0: 		} else if (n == 0) {
michael@0: 			/* XXX warn? */
michael@0: 			break;
michael@0: 		}
michael@0: 		for (i = 0; i < n; ++i) {
michael@0: 			ev_uint8_t sig = signals[i];
michael@0: 			if (sig < NSIG)
michael@0: 				ncaught[sig]++;
michael@0: 		}
michael@0: 	}
michael@0: 
michael@0: 	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
michael@0: 	for (i = 0; i < NSIG; ++i) {
michael@0: 		if (ncaught[i])
michael@0: 			evmap_signal_active(base, i, ncaught[i]);
michael@0: 	}
michael@0: 	EVBASE_RELEASE_LOCK(base, th_base_lock);
michael@0: }
michael@0: 
michael@0: int
michael@0: evsig_init(struct event_base *base)
michael@0: {
michael@0: 	/*
michael@0: 	 * Our signal handler is going to write to one end of the socket
michael@0: 	 * pair to wake up our event loop.  The event loop then scans for
michael@0: 	 * signals that got delivered.
michael@0: 	 */
michael@0: 	if (evutil_socketpair(
michael@0: 		    AF_UNIX, SOCK_STREAM, 0, base->sig.ev_signal_pair) == -1) {
michael@0: #ifdef WIN32
michael@0: 		/* Make this nonfatal on win32, where sometimes people
michael@0: 		   have localhost firewalled. */
michael@0: 		event_sock_warn(-1, "%s: socketpair", __func__);
michael@0: #else
michael@0: 		event_sock_err(1, -1, "%s: socketpair", __func__);
michael@0: #endif
michael@0: 		return -1;
michael@0: 	}
michael@0: 
michael@0: 	evutil_make_socket_closeonexec(base->sig.ev_signal_pair[0]);
michael@0: 	evutil_make_socket_closeonexec(base->sig.ev_signal_pair[1]);
michael@0: 	base->sig.sh_old = NULL;
michael@0: 	base->sig.sh_old_max = 0;
michael@0: 
michael@0: 	evutil_make_socket_nonblocking(base->sig.ev_signal_pair[0]);
michael@0: 	evutil_make_socket_nonblocking(base->sig.ev_signal_pair[1]);
michael@0: 
michael@0: 	event_assign(&base->sig.ev_signal, base, base->sig.ev_signal_pair[1],
michael@0: 		EV_READ | EV_PERSIST, evsig_cb, base);
michael@0: 
michael@0: 	base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL;
michael@0: 	event_priority_set(&base->sig.ev_signal, 0);
michael@0: 
michael@0: 	base->evsigsel = &evsigops;
michael@0: 
michael@0: 	return 0;
michael@0: }
michael@0: 
michael@0: /* Helper: set the signal handler for evsignal to handler in base, so that
michael@0:  * we can restore the original handler when we clear the current one. */
michael@0: int
michael@0: _evsig_set_handler(struct event_base *base,
michael@0:     int evsignal, void (__cdecl *handler)(int))
michael@0: {
michael@0: #ifdef _EVENT_HAVE_SIGACTION
michael@0: 	struct sigaction sa;
michael@0: #else
michael@0: 	ev_sighandler_t sh;
michael@0: #endif
michael@0: 	struct evsig_info *sig = &base->sig;
michael@0: 	void *p;
michael@0: 
michael@0: 	/*
michael@0: 	 * resize saved signal handler array up to the highest signal number.
michael@0: 	 * a dynamic array is used to keep footprint on the low side.
michael@0: 	 */
michael@0: 	if (evsignal >= sig->sh_old_max) {
michael@0: 		int new_max = evsignal + 1;
michael@0: 		event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",
michael@0: 			    __func__, evsignal, sig->sh_old_max));
michael@0: 		p = mm_realloc(sig->sh_old, new_max * sizeof(*sig->sh_old));
michael@0: 		if (p == NULL) {
michael@0: 			event_warn("realloc");
michael@0: 			return (-1);
michael@0: 		}
michael@0: 
michael@0: 		memset((char *)p + sig->sh_old_max * sizeof(*sig->sh_old),
michael@0: 		    0, (new_max - sig->sh_old_max) * sizeof(*sig->sh_old));
michael@0: 
michael@0: 		sig->sh_old_max = new_max;
michael@0: 		sig->sh_old = p;
michael@0: 	}
michael@0: 
michael@0: 	/* allocate space for previous handler out of dynamic array */
michael@0: 	sig->sh_old[evsignal] = mm_malloc(sizeof *sig->sh_old[evsignal]);
michael@0: 	if (sig->sh_old[evsignal] == NULL) {
michael@0: 		event_warn("malloc");
michael@0: 		return (-1);
michael@0: 	}
michael@0: 
michael@0: 	/* save previous handler and setup new handler */
michael@0: #ifdef _EVENT_HAVE_SIGACTION
michael@0: 	memset(&sa, 0, sizeof(sa));
michael@0: 	sa.sa_handler = handler;
michael@0: 	sa.sa_flags |= SA_RESTART;
michael@0: 	sigfillset(&sa.sa_mask);
michael@0: 
michael@0: 	if (sigaction(evsignal, &sa, sig->sh_old[evsignal]) == -1) {
michael@0: 		event_warn("sigaction");
michael@0: 		mm_free(sig->sh_old[evsignal]);
michael@0: 		sig->sh_old[evsignal] = NULL;
michael@0: 		return (-1);
michael@0: 	}
michael@0: #else
michael@0: 	if ((sh = signal(evsignal, handler)) == SIG_ERR) {
michael@0: 		event_warn("signal");
michael@0: 		mm_free(sig->sh_old[evsignal]);
michael@0: 		sig->sh_old[evsignal] = NULL;
michael@0: 		return (-1);
michael@0: 	}
michael@0: 	*sig->sh_old[evsignal] = sh;
michael@0: #endif
michael@0: 
michael@0: 	return (0);
michael@0: }
michael@0: 
michael@0: static int
michael@0: evsig_add(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
michael@0: {
michael@0: 	struct evsig_info *sig = &base->sig;
michael@0: 	(void)p;
michael@0: 
michael@0: 	EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
michael@0: 
michael@0: 	/* catch signals if they happen quickly */
michael@0: 	EVSIGBASE_LOCK();
michael@0: 	if (evsig_base != base && evsig_base_n_signals_added) {
michael@0: 		event_warnx("Added a signal to event base %p with signals "
michael@0: 		    "already added to event_base %p.  Only one can have "
michael@0: 		    "signals at a time with the %s backend.  The base with "
michael@0: 		    "the most recently added signal or the most recent "
michael@0: 		    "event_base_loop() call gets preference; do "
michael@0: 		    "not rely on this behavior in future Libevent versions.",
michael@0: 		    base, evsig_base, base->evsel->name);
michael@0: 	}
michael@0: 	evsig_base = base;
michael@0: 	evsig_base_n_signals_added = ++sig->ev_n_signals_added;
michael@0: 	evsig_base_fd = base->sig.ev_signal_pair[0];
michael@0: 	EVSIGBASE_UNLOCK();
michael@0: 
michael@0: 	event_debug(("%s: %d: changing signal handler", __func__, (int)evsignal));
michael@0: 	if (_evsig_set_handler(base, (int)evsignal, evsig_handler) == -1) {
michael@0: 		goto err;
michael@0: 	}
michael@0: 
michael@0: 
michael@0: 	if (!sig->ev_signal_added) {
michael@0: 		if (event_add(&sig->ev_signal, NULL))
michael@0: 			goto err;
michael@0: 		sig->ev_signal_added = 1;
michael@0: 	}
michael@0: 
michael@0: 	return (0);
michael@0: 
michael@0: err:
michael@0: 	EVSIGBASE_LOCK();
michael@0: 	--evsig_base_n_signals_added;
michael@0: 	--sig->ev_n_signals_added;
michael@0: 	EVSIGBASE_UNLOCK();
michael@0: 	return (-1);
michael@0: }
michael@0: 
michael@0: int
michael@0: _evsig_restore_handler(struct event_base *base, int evsignal)
michael@0: {
michael@0: 	int ret = 0;
michael@0: 	struct evsig_info *sig = &base->sig;
michael@0: #ifdef _EVENT_HAVE_SIGACTION
michael@0: 	struct sigaction *sh;
michael@0: #else
michael@0: 	ev_sighandler_t *sh;
michael@0: #endif
michael@0: 
michael@0: 	/* restore previous handler */
michael@0: 	sh = sig->sh_old[evsignal];
michael@0: 	sig->sh_old[evsignal] = NULL;
michael@0: #ifdef _EVENT_HAVE_SIGACTION
michael@0: 	if (sigaction(evsignal, sh, NULL) == -1) {
michael@0: 		event_warn("sigaction");
michael@0: 		ret = -1;
michael@0: 	}
michael@0: #else
michael@0: 	if (signal(evsignal, *sh) == SIG_ERR) {
michael@0: 		event_warn("signal");
michael@0: 		ret = -1;
michael@0: 	}
michael@0: #endif
michael@0: 
michael@0: 	mm_free(sh);
michael@0: 
michael@0: 	return ret;
michael@0: }
michael@0: 
michael@0: static int
michael@0: evsig_del(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
michael@0: {
michael@0: 	EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
michael@0: 
michael@0: 	event_debug(("%s: "EV_SOCK_FMT": restoring signal handler",
michael@0: 		__func__, EV_SOCK_ARG(evsignal)));
michael@0: 
michael@0: 	EVSIGBASE_LOCK();
michael@0: 	--evsig_base_n_signals_added;
michael@0: 	--base->sig.ev_n_signals_added;
michael@0: 	EVSIGBASE_UNLOCK();
michael@0: 
michael@0: 	return (_evsig_restore_handler(base, (int)evsignal));
michael@0: }
michael@0: 
michael@0: static void __cdecl
michael@0: evsig_handler(int sig)
michael@0: {
michael@0: 	int save_errno = errno;
michael@0: #ifdef WIN32
michael@0: 	int socket_errno = EVUTIL_SOCKET_ERROR();
michael@0: #endif
michael@0: 	ev_uint8_t msg;
michael@0: 
michael@0: 	if (evsig_base == NULL) {
michael@0: 		event_warnx(
michael@0: 			"%s: received signal %d, but have no base configured",
michael@0: 			__func__, sig);
michael@0: 		return;
michael@0: 	}
michael@0: 
michael@0: #ifndef _EVENT_HAVE_SIGACTION
michael@0: 	signal(sig, evsig_handler);
michael@0: #endif
michael@0: 
michael@0: 	/* Wake up our notification mechanism */
michael@0: 	msg = sig;
michael@0: 	send(evsig_base_fd, (char*)&msg, 1, 0);
michael@0: 	errno = save_errno;
michael@0: #ifdef WIN32
michael@0: 	EVUTIL_SET_SOCKET_ERROR(socket_errno);
michael@0: #endif
michael@0: }
michael@0: 
michael@0: void
michael@0: evsig_dealloc(struct event_base *base)
michael@0: {
michael@0: 	int i = 0;
michael@0: 	if (base->sig.ev_signal_added) {
michael@0: 		event_del(&base->sig.ev_signal);
michael@0: 		base->sig.ev_signal_added = 0;
michael@0: 	}
michael@0: 	/* debug event is created in evsig_init/event_assign even when
michael@0: 	 * ev_signal_added == 0, so unassign is required */
michael@0: 	event_debug_unassign(&base->sig.ev_signal);
michael@0: 
michael@0: 	for (i = 0; i < NSIG; ++i) {
michael@0: 		if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
michael@0: 			_evsig_restore_handler(base, i);
michael@0: 	}
michael@0: 	EVSIGBASE_LOCK();
michael@0: 	if (base == evsig_base) {
michael@0: 		evsig_base = NULL;
michael@0: 		evsig_base_n_signals_added = 0;
michael@0: 		evsig_base_fd = -1;
michael@0: 	}
michael@0: 	EVSIGBASE_UNLOCK();
michael@0: 
michael@0: 	if (base->sig.ev_signal_pair[0] != -1) {
michael@0: 		evutil_closesocket(base->sig.ev_signal_pair[0]);
michael@0: 		base->sig.ev_signal_pair[0] = -1;
michael@0: 	}
michael@0: 	if (base->sig.ev_signal_pair[1] != -1) {
michael@0: 		evutil_closesocket(base->sig.ev_signal_pair[1]);
michael@0: 		base->sig.ev_signal_pair[1] = -1;
michael@0: 	}
michael@0: 	base->sig.sh_old_max = 0;
michael@0: 
michael@0: 	/* per index frees are handled in evsig_del() */
michael@0: 	if (base->sig.sh_old) {
michael@0: 		mm_free(base->sig.sh_old);
michael@0: 		base->sig.sh_old = NULL;
michael@0: 	}
michael@0: }
michael@0: 
michael@0: #ifndef _EVENT_DISABLE_THREAD_SUPPORT
michael@0: int
michael@0: evsig_global_setup_locks_(const int enable_locks)
michael@0: {
michael@0: 	EVTHREAD_SETUP_GLOBAL_LOCK(evsig_base_lock, 0);
michael@0: 	return 0;
michael@0: }
michael@0: #endif