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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"

 #ifdef WIN32

 #define WIN32_LEAN_AND_MEAN

 #include <winsock2.h>

 #include <windows.h>

 #undef WIN32_LEAN_AND_MEAN

 #endif

 #include <sys/types.h>

 #ifdef _EVENT_HAVE_SYS_TIME_H

 #include <sys/time.h>

 #endif

 #include <sys/queue.h>

 #ifdef _EVENT_HAVE_SYS_SOCKET_H

 #include <sys/socket.h>

 #endif

 #include <signal.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #ifdef _EVENT_HAVE_UNISTD_H

 #include <unistd.h>

 #endif

 #include <errno.h>

 #ifdef _EVENT_HAVE_FCNTL_H

 #include <fcntl.h>

 #endif

 #include "event2/event.h"

 #include "event2/event_struct.h"

 #include "event-internal.h"

 #include "event2/util.h"

 #include "evsignal-internal.h"

 #include "log-internal.h"

 #include "evmap-internal.h"

 #include "evthread-internal.h"

 /*

   signal.c

   This is the signal-handling implementation we use for backends that don't

   have a better way to do signal handling.  It uses sigaction() or signal()

   to set a signal handler, and a socket pair to tell the event base when

   Note that I said "the event base" : only one event base can be set up to use

   this at a time.  For historical reasons and backward compatibility, if you

   add an event for a signal to event_base A, then add an event for a signal

   (any signal!) to event_base B, event_base B will get informed about the

   signal, but event_base A won't.

   It would be neat to change this behavior in some future version of Libevent.

   kqueue already does something far more sensible.  We can make all backends

   on Linux do a reasonable thing using signalfd.

 */

 #ifndef WIN32

 /* Windows wants us to call our signal handlers as __cdecl.  Nobody else

  * expects you to do anything crazy like this. */

 #define __cdecl

 #endif

 static int evsig_add(struct event_base *, evutil_socket_t, short, short, void *);

 static int evsig_del(struct event_base *, evutil_socket_t, short, short, void *);

 static const struct eventop evsigops = {

 	"signal",

 	NULL,

 	evsig_add,

 	evsig_del,

 	NULL,

 	NULL,

 	0, 0, 0

 };

 #ifndef _EVENT_DISABLE_THREAD_SUPPORT

 /* Lock for evsig_base and evsig_base_n_signals_added fields. */

 static void *evsig_base_lock = NULL;

 #endif

 /* The event base that's currently getting informed about signals. */

 static struct event_base *evsig_base = NULL;

 /* A copy of evsig_base->sigev_n_signals_added. */

 static int evsig_base_n_signals_added = 0;

 static evutil_socket_t evsig_base_fd = -1;

 static void __cdecl evsig_handler(int sig);

 #define EVSIGBASE_LOCK() EVLOCK_LOCK(evsig_base_lock, 0)

 #define EVSIGBASE_UNLOCK() EVLOCK_UNLOCK(evsig_base_lock, 0)

 void

 evsig_set_base(struct event_base *base)

 {

 	EVSIGBASE_LOCK();

 	evsig_base = base;

 	evsig_base_n_signals_added = base->sig.ev_n_signals_added;

 	evsig_base_fd = base->sig.ev_signal_pair[0];

 	EVSIGBASE_UNLOCK();

 }

 /* Callback for when the signal handler write a byte to our signaling socket */

 static void

 evsig_cb(evutil_socket_t fd, short what, void *arg)

 {

 	static char signals[1024];

 	ev_ssize_t n;

 	int i;

 	int ncaught[NSIG];

 	struct event_base *base;

 	base = arg;

 	memset(&ncaught, 0, sizeof(ncaught));

 	while (1) {

 		n = recv(fd, signals, sizeof(signals), 0);

 		if (n == -1) {

 			int err = evutil_socket_geterror(fd);

 			if (! EVUTIL_ERR_RW_RETRIABLE(err))

 				event_sock_err(1, fd, "%s: recv", __func__);

 			break;

 		} else if (n == 0) {

 			/* XXX warn? */

 			break;

 		}

 		for (i = 0; i < n; ++i) {

 			ev_uint8_t sig = signals[i];

 			if (sig < NSIG)

 				ncaught[sig]++;

 		}

 	}

 	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

 	for (i = 0; i < NSIG; ++i) {

 		if (ncaught[i])

 			evmap_signal_active(base, i, ncaught[i]);

 	}

 	EVBASE_RELEASE_LOCK(base, th_base_lock);

 }

 int

 evsig_init(struct event_base *base)

 {

 	/*

 	 * Our signal handler is going to write to one end of the socket

 	 * pair to wake up our event loop.  The event loop then scans for

 	 * signals that got delivered.

 	 */

 	if (evutil_socketpair(

 		    AF_UNIX, SOCK_STREAM, 0, base->sig.ev_signal_pair) == -1) {

 #ifdef WIN32

 		/* Make this nonfatal on win32, where sometimes people

 		   have localhost firewalled. */

 		event_sock_warn(-1, "%s: socketpair", __func__);

 #else

 		event_sock_err(1, -1, "%s: socketpair", __func__);

 #endif

 		return -1;

 	}

 	evutil_make_socket_closeonexec(base->sig.ev_signal_pair[0]);

 	evutil_make_socket_closeonexec(base->sig.ev_signal_pair[1]);

 	base->sig.sh_old = NULL;

 	base->sig.sh_old_max = 0;

 	evutil_make_socket_nonblocking(base->sig.ev_signal_pair[0]);

 	evutil_make_socket_nonblocking(base->sig.ev_signal_pair[1]);

 	event_assign(&base->sig.ev_signal, base, base->sig.ev_signal_pair[1],

 		EV_READ | EV_PERSIST, evsig_cb, base);

 	base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL;

 	event_priority_set(&base->sig.ev_signal, 0);

 	base->evsigsel = &evsigops;

 	return 0;

 }

 /* Helper: set the signal handler for evsignal to handler in base, so that

  * we can restore the original handler when we clear the current one. */

 int

 _evsig_set_handler(struct event_base *base,

     int evsignal, void (__cdecl *handler)(int))

 {

 #ifdef _EVENT_HAVE_SIGACTION

 	struct sigaction sa;

 #else

 	ev_sighandler_t sh;

 #endif

 	struct evsig_info *sig = &base->sig;

 	void *p;

 	/*

 	 * resize saved signal handler array up to the highest signal number.

 	 * a dynamic array is used to keep footprint on the low side.

 	 */

 	if (evsignal >= sig->sh_old_max) {

 		int new_max = evsignal + 1;

 		event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",

 			    __func__, evsignal, sig->sh_old_max));

 		p = mm_realloc(sig->sh_old, new_max * sizeof(*sig->sh_old));

 		if (p == NULL) {

 			event_warn("realloc");

 			return (-1);

 		}

 		memset((char *)p + sig->sh_old_max * sizeof(*sig->sh_old),

 		    0, (new_max - sig->sh_old_max) * sizeof(*sig->sh_old));

 		sig->sh_old_max = new_max;

 		sig->sh_old = p;

 	}

 	/* allocate space for previous handler out of dynamic array */

 	sig->sh_old[evsignal] = mm_malloc(sizeof *sig->sh_old[evsignal]);

 	if (sig->sh_old[evsignal] == NULL) {

 		event_warn("malloc");

 		return (-1);

 	}

 	/* save previous handler and setup new handler */

 #ifdef _EVENT_HAVE_SIGACTION

 	memset(&sa, 0, sizeof(sa));

 	sa.sa_handler = handler;

 	sa.sa_flags |= SA_RESTART;

 	sigfillset(&sa.sa_mask);

 	if (sigaction(evsignal, &sa, sig->sh_old[evsignal]) == -1) {

 		event_warn("sigaction");

 		mm_free(sig->sh_old[evsignal]);

 		sig->sh_old[evsignal] = NULL;

 		return (-1);

 	}

 #else

 	if ((sh = signal(evsignal, handler)) == SIG_ERR) {

 		event_warn("signal");

 		mm_free(sig->sh_old[evsignal]);

 		sig->sh_old[evsignal] = NULL;

 		return (-1);

 	}

 	*sig->sh_old[evsignal] = sh;

 #endif

 	return (0);

 }

 static int

 evsig_add(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)

 {

 	struct evsig_info *sig = &base->sig;

 	(void)p;

 	EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);

 	/* catch signals if they happen quickly */

 	EVSIGBASE_LOCK();

 	if (evsig_base != base && evsig_base_n_signals_added) {

 		event_warnx("Added a signal to event base %p with signals "

 		    "already added to event_base %p.  Only one can have "

 		    "signals at a time with the %s backend.  The base with "

 		    "the most recently added signal or the most recent "

 		    "event_base_loop() call gets preference; do "

 		    "not rely on this behavior in future Libevent versions.",

 		    base, evsig_base, base->evsel->name);

 	}

 	evsig_base = base;

 	evsig_base_n_signals_added = ++sig->ev_n_signals_added;

 	evsig_base_fd = base->sig.ev_signal_pair[0];

 	EVSIGBASE_UNLOCK();

 	event_debug(("%s: %d: changing signal handler", __func__, (int)evsignal));

 	if (_evsig_set_handler(base, (int)evsignal, evsig_handler) == -1) {

 		goto err;

 	}

 	if (!sig->ev_signal_added) {

 		if (event_add(&sig->ev_signal, NULL))

 			goto err;

 		sig->ev_signal_added = 1;

 	}

 	return (0);

 err:

 	EVSIGBASE_LOCK();

 	--evsig_base_n_signals_added;

 	--sig->ev_n_signals_added;

 	EVSIGBASE_UNLOCK();

 	return (-1);

 }

 int

 _evsig_restore_handler(struct event_base *base, int evsignal)

 {

 	int ret = 0;

 	struct evsig_info *sig = &base->sig;

 #ifdef _EVENT_HAVE_SIGACTION

 	struct sigaction *sh;

 #else

 	ev_sighandler_t *sh;

 #endif

 	/* restore previous handler */

 	sh = sig->sh_old[evsignal];

 	sig->sh_old[evsignal] = NULL;

 #ifdef _EVENT_HAVE_SIGACTION

 	if (sigaction(evsignal, sh, NULL) == -1) {

 		event_warn("sigaction");

 		ret = -1;

 	}

 #else

 	if (signal(evsignal, *sh) == SIG_ERR) {

 		event_warn("signal");

 		ret = -1;

 	}

 #endif

 	mm_free(sh);

 	return ret;

 }

 static int

 evsig_del(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)

 {

 	EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);

 	event_debug(("%s: "EV_SOCK_FMT": restoring signal handler",

 		__func__, EV_SOCK_ARG(evsignal)));

 	EVSIGBASE_LOCK();

 	--evsig_base_n_signals_added;

 	--base->sig.ev_n_signals_added;

 	EVSIGBASE_UNLOCK();

 	return (_evsig_restore_handler(base, (int)evsignal));

 }

 static void __cdecl

 evsig_handler(int sig)

 {

 	int save_errno = errno;

 #ifdef WIN32

 	int socket_errno = EVUTIL_SOCKET_ERROR();

 #endif

 	ev_uint8_t msg;

 	if (evsig_base == NULL) {

 		event_warnx(

 			"%s: received signal %d, but have no base configured",

 			__func__, sig);

 		return;

 	}

 #ifndef _EVENT_HAVE_SIGACTION

 	signal(sig, evsig_handler);

 #endif

 	/* Wake up our notification mechanism */

 	msg = sig;

 	send(evsig_base_fd, (char*)&msg, 1, 0);

 	errno = save_errno;

 #ifdef WIN32

 	EVUTIL_SET_SOCKET_ERROR(socket_errno);

 #endif

 }

 void

 evsig_dealloc(struct event_base *base)

 {

 	int i = 0;

 	if (base->sig.ev_signal_added) {

 		event_del(&base->sig.ev_signal);

 		base->sig.ev_signal_added = 0;

 	}

 	/* debug event is created in evsig_init/event_assign even when

 	 * ev_signal_added == 0, so unassign is required */

 	event_debug_unassign(&base->sig.ev_signal);

 	for (i = 0; i < NSIG; ++i) {

 		if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)

 			_evsig_restore_handler(base, i);

 	}

 	EVSIGBASE_LOCK();

 	if (base == evsig_base) {

 		evsig_base = NULL;

 		evsig_base_n_signals_added = 0;

 		evsig_base_fd = -1;

 	}

 	EVSIGBASE_UNLOCK();

 	if (base->sig.ev_signal_pair[0] != -1) {

 		evutil_closesocket(base->sig.ev_signal_pair[0]);

 		base->sig.ev_signal_pair[0] = -1;

 	}

 	if (base->sig.ev_signal_pair[1] != -1) {

 		evutil_closesocket(base->sig.ev_signal_pair[1]);

 		base->sig.ev_signal_pair[1] = -1;

 	}

 	base->sig.sh_old_max = 0;

 	/* per index frees are handled in evsig_del() */

 	if (base->sig.sh_old) {

 		mm_free(base->sig.sh_old);

 		base->sig.sh_old = NULL;

 	}

 }

 #ifndef _EVENT_DISABLE_THREAD_SUPPORT

 int

 evsig_global_setup_locks_(const int enable_locks)

 {

 	EVTHREAD_SETUP_GLOBAL_LOCK(evsig_base_lock, 0);

 	return 0;

 }

 #endif