/*	$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