diff options
Diffstat (limited to 'libevent/signal.c')
| -rw-r--r-- | libevent/signal.c | 357 |
1 files changed, 357 insertions, 0 deletions
diff --git a/libevent/signal.c b/libevent/signal.c new file mode 100644 index 00000000000..74fa23f688a --- /dev/null +++ b/libevent/signal.c @@ -0,0 +1,357 @@ +/* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */ + +/* + * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu> + * All rights reserved. + * + * 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. + */ +#ifdef HAVE_CONFIG_H +#include "config.h" +#endif + +#ifdef WIN32 +#define WIN32_LEAN_AND_MEAN +#include <winsock2.h> +#include <windows.h> +#undef WIN32_LEAN_AND_MEAN +#endif +#include <sys/types.h> +#ifdef HAVE_SYS_TIME_H +#include <sys/time.h> +#endif +#include <sys/queue.h> +#ifdef HAVE_SYS_SOCKET_H +#include <sys/socket.h> +#endif +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif +#include <errno.h> +#ifdef HAVE_FCNTL_H +#include <fcntl.h> +#endif +#include <assert.h> + +#include "event.h" +#include "event-internal.h" +#include "evsignal.h" +#include "evutil.h" +#include "log.h" + +struct event_base *evsignal_base = NULL; + +static void evsignal_handler(int sig); + +/* Callback for when the signal handler write a byte to our signaling socket */ +static void +evsignal_cb(int fd, short what, void *arg) +{ + static char signals[1]; +#ifdef WIN32 + SSIZE_T n; +#else + ssize_t n; +#endif + + n = recv(fd, signals, sizeof(signals), 0); + if (n == -1) + event_err(1, "%s: read", __func__); +} + +#ifdef HAVE_SETFD +#define FD_CLOSEONEXEC(x) do { \ + if (fcntl(x, F_SETFD, 1) == -1) \ + event_warn("fcntl(%d, F_SETFD)", x); \ +} while (0) +#else +#define FD_CLOSEONEXEC(x) +#endif + +int +evsignal_init(struct event_base *base) +{ + int i; + + /* + * 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_warn("%s: socketpair", __func__); +#else + event_err(1, "%s: socketpair", __func__); +#endif + return -1; + } + + FD_CLOSEONEXEC(base->sig.ev_signal_pair[0]); + FD_CLOSEONEXEC(base->sig.ev_signal_pair[1]); + base->sig.sh_old = NULL; + base->sig.sh_old_max = 0; + base->sig.evsignal_caught = 0; + memset(&base->sig.evsigcaught, 0, sizeof(sig_atomic_t)*NSIG); + /* initialize the queues for all events */ + for (i = 0; i < NSIG; ++i) + TAILQ_INIT(&base->sig.evsigevents[i]); + + evutil_make_socket_nonblocking(base->sig.ev_signal_pair[0]); + + event_set(&base->sig.ev_signal, base->sig.ev_signal_pair[1], + EV_READ | EV_PERSIST, evsignal_cb, &base->sig.ev_signal); + base->sig.ev_signal.ev_base = base; + base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL; + + 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 +_evsignal_set_handler(struct event_base *base, + int evsignal, void (*handler)(int)) +{ +#ifdef HAVE_SIGACTION + struct sigaction sa; +#else + ev_sighandler_t sh; +#endif + struct evsignal_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 = 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] = 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 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"); + free(sig->sh_old[evsignal]); + return (-1); + } +#else + if ((sh = signal(evsignal, handler)) == SIG_ERR) { + event_warn("signal"); + free(sig->sh_old[evsignal]); + return (-1); + } + *sig->sh_old[evsignal] = sh; +#endif + + return (0); +} + +int +evsignal_add(struct event *ev) +{ + int evsignal; + struct event_base *base = ev->ev_base; + struct evsignal_info *sig = &ev->ev_base->sig; + + if (ev->ev_events & (EV_READ|EV_WRITE)) + event_errx(1, "%s: EV_SIGNAL incompatible use", __func__); + evsignal = EVENT_SIGNAL(ev); + assert(evsignal >= 0 && evsignal < NSIG); + if (TAILQ_EMPTY(&sig->evsigevents[evsignal])) { + event_debug(("%s: %p: changing signal handler", __func__, ev)); + if (_evsignal_set_handler( + base, evsignal, evsignal_handler) == -1) + return (-1); + + /* catch signals if they happen quickly */ + evsignal_base = base; + + if (!sig->ev_signal_added) { + if (event_add(&sig->ev_signal, NULL)) + return (-1); + sig->ev_signal_added = 1; + } + } + + /* multiple events may listen to the same signal */ + TAILQ_INSERT_TAIL(&sig->evsigevents[evsignal], ev, ev_signal_next); + + return (0); +} + +int +_evsignal_restore_handler(struct event_base *base, int evsignal) +{ + int ret = 0; + struct evsignal_info *sig = &base->sig; +#ifdef 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 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 + free(sh); + + return ret; +} + +int +evsignal_del(struct event *ev) +{ + struct event_base *base = ev->ev_base; + struct evsignal_info *sig = &base->sig; + int evsignal = EVENT_SIGNAL(ev); + + assert(evsignal >= 0 && evsignal < NSIG); + + /* multiple events may listen to the same signal */ + TAILQ_REMOVE(&sig->evsigevents[evsignal], ev, ev_signal_next); + + if (!TAILQ_EMPTY(&sig->evsigevents[evsignal])) + return (0); + + event_debug(("%s: %p: restoring signal handler", __func__, ev)); + + return (_evsignal_restore_handler(ev->ev_base, EVENT_SIGNAL(ev))); +} + +static void +evsignal_handler(int sig) +{ + int save_errno = errno; + + if (evsignal_base == NULL) { + event_warn( + "%s: received signal %d, but have no base configured", + __func__, sig); + return; + } + + evsignal_base->sig.evsigcaught[sig]++; + evsignal_base->sig.evsignal_caught = 1; + +#ifndef HAVE_SIGACTION + signal(sig, evsignal_handler); +#endif + + /* Wake up our notification mechanism */ + send(evsignal_base->sig.ev_signal_pair[0], "a", 1, 0); + errno = save_errno; +} + +void +evsignal_process(struct event_base *base) +{ + struct evsignal_info *sig = &base->sig; + struct event *ev, *next_ev; + sig_atomic_t ncalls; + int i; + + base->sig.evsignal_caught = 0; + for (i = 1; i < NSIG; ++i) { + ncalls = sig->evsigcaught[i]; + if (ncalls == 0) + continue; + sig->evsigcaught[i] -= ncalls; + + for (ev = TAILQ_FIRST(&sig->evsigevents[i]); + ev != NULL; ev = next_ev) { + next_ev = TAILQ_NEXT(ev, ev_signal_next); + if (!(ev->ev_events & EV_PERSIST)) + event_del(ev); + event_active(ev, EV_SIGNAL, ncalls); + } + + } +} + +void +evsignal_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; + } + for (i = 0; i < NSIG; ++i) { + if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL) + _evsignal_restore_handler(base, i); + } + + EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[0]); + base->sig.ev_signal_pair[0] = -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 evsignal_del() */ + free(base->sig.sh_old); +} |