--- /dev/null
+/* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
+
+/*
+ * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
+ * Copyright 2007-2010 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)
+{
+#ifndef _EVENT_DISABLE_THREAD_SUPPORT
+ if (! evsig_base_lock)
+ EVTHREAD_ALLOC_LOCK(evsig_base_lock, 0);
+#endif
+
+ /*
+ * 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: %d: restoring signal handler", __func__, 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);
+ event_debug_unassign(&base->sig.ev_signal);
+ base->sig.ev_signal_added = 0;
+ }
+
+ 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;
+ }
+}
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