X-Git-Url: https://arthur.barton.de/cgi-bin/gitweb.cgi?p=netatalk.git;a=blobdiff_plain;f=libevent%2Fsignal.c;fp=libevent%2Fsignal.c;h=ec27ea88428f966b2754a78c08fe24f5f43c857b;hp=0000000000000000000000000000000000000000;hb=9c8a21a5a13808bab520bd257b3d0a6fe16c6b07;hpb=4cafdfb9f307e9cc6131a79d09011ef09f3b8f20 diff --git a/libevent/signal.c b/libevent/signal.c new file mode 100644 index 00000000..ec27ea88 --- /dev/null +++ b/libevent/signal.c @@ -0,0 +1,438 @@ +/* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */ + +/* + * Copyright 2000-2007 Niels Provos + * 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 +#include +#undef WIN32_LEAN_AND_MEAN +#endif +#include +#ifdef _EVENT_HAVE_SYS_TIME_H +#include +#endif +#include +#ifdef _EVENT_HAVE_SYS_SOCKET_H +#include +#endif +#include +#include +#include +#include +#ifdef _EVENT_HAVE_UNISTD_H +#include +#endif +#include +#ifdef _EVENT_HAVE_FCNTL_H +#include +#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; + } +}