1 /* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
4 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
5 * Copyright 2007-2012 Niels Provos and Nick Mathewson
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include "event2/event-config.h"
30 #include "evconfig-private.h"
33 #define WIN32_LEAN_AND_MEAN
36 #undef WIN32_LEAN_AND_MEAN
38 #include <sys/types.h>
39 #ifdef EVENT__HAVE_SYS_TIME_H
42 #include <sys/queue.h>
43 #ifdef EVENT__HAVE_SYS_SOCKET_H
44 #include <sys/socket.h>
50 #ifdef EVENT__HAVE_UNISTD_H
54 #ifdef EVENT__HAVE_FCNTL_H
58 #include "event2/event.h"
59 #include "event2/event_struct.h"
60 #include "event-internal.h"
61 #include "event2/util.h"
62 #include "evsignal-internal.h"
63 #include "log-internal.h"
64 #include "evmap-internal.h"
65 #include "evthread-internal.h"
70 This is the signal-handling implementation we use for backends that don't
71 have a better way to do signal handling. It uses sigaction() or signal()
72 to set a signal handler, and a socket pair to tell the event base when
74 Note that I said "the event base" : only one event base can be set up to use
75 this at a time. For historical reasons and backward compatibility, if you
76 add an event for a signal to event_base A, then add an event for a signal
77 (any signal!) to event_base B, event_base B will get informed about the
78 signal, but event_base A won't.
80 It would be neat to change this behavior in some future version of Libevent.
81 kqueue already does something far more sensible. We can make all backends
82 on Linux do a reasonable thing using signalfd.
86 /* Windows wants us to call our signal handlers as __cdecl. Nobody else
87 * expects you to do anything crazy like this. */
93 static int evsig_add(struct event_base *, evutil_socket_t, short, short, void *);
94 static int evsig_del(struct event_base *, evutil_socket_t, short, short, void *);
96 static const struct eventop evsigops = {
106 #ifndef EVENT__DISABLE_THREAD_SUPPORT
107 /* Lock for evsig_base and evsig_base_n_signals_added fields. */
108 static void *evsig_base_lock = NULL;
110 /* The event base that's currently getting informed about signals. */
111 static struct event_base *evsig_base = NULL;
112 /* A copy of evsig_base->sigev_n_signals_added. */
113 static int evsig_base_n_signals_added = 0;
114 static evutil_socket_t evsig_base_fd = -1;
116 static void __cdecl evsig_handler(int sig);
118 #define EVSIGBASE_LOCK() EVLOCK_LOCK(evsig_base_lock, 0)
119 #define EVSIGBASE_UNLOCK() EVLOCK_UNLOCK(evsig_base_lock, 0)
122 evsig_set_base_(struct event_base *base)
126 evsig_base_n_signals_added = base->sig.ev_n_signals_added;
127 evsig_base_fd = base->sig.ev_signal_pair[1];
131 /* Callback for when the signal handler write a byte to our signaling socket */
133 evsig_cb(evutil_socket_t fd, short what, void *arg)
135 static char signals[1024];
139 struct event_base *base;
143 memset(&ncaught, 0, sizeof(ncaught));
147 n = recv(fd, signals, sizeof(signals), 0);
149 n = read(fd, signals, sizeof(signals));
152 int err = evutil_socket_geterror(fd);
153 if (! EVUTIL_ERR_RW_RETRIABLE(err))
154 event_sock_err(1, fd, "%s: recv", __func__);
160 for (i = 0; i < n; ++i) {
161 ev_uint8_t sig = signals[i];
167 EVBASE_ACQUIRE_LOCK(base, th_base_lock);
168 for (i = 0; i < NSIG; ++i) {
170 evmap_signal_active_(base, i, ncaught[i]);
172 EVBASE_RELEASE_LOCK(base, th_base_lock);
176 evsig_init_(struct event_base *base)
179 * Our signal handler is going to write to one end of the socket
180 * pair to wake up our event loop. The event loop then scans for
181 * signals that got delivered.
183 if (evutil_make_internal_pipe_(base->sig.ev_signal_pair) == -1) {
185 /* Make this nonfatal on win32, where sometimes people
186 have localhost firewalled. */
187 event_sock_warn(-1, "%s: socketpair", __func__);
189 event_sock_err(1, -1, "%s: socketpair", __func__);
194 if (base->sig.sh_old) {
195 mm_free(base->sig.sh_old);
197 base->sig.sh_old = NULL;
198 base->sig.sh_old_max = 0;
200 event_assign(&base->sig.ev_signal, base, base->sig.ev_signal_pair[0],
201 EV_READ | EV_PERSIST, evsig_cb, base);
203 base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL;
204 event_priority_set(&base->sig.ev_signal, 0);
206 base->evsigsel = &evsigops;
211 /* Helper: set the signal handler for evsignal to handler in base, so that
212 * we can restore the original handler when we clear the current one. */
214 evsig_set_handler_(struct event_base *base,
215 int evsignal, void (__cdecl *handler)(int))
217 #ifdef EVENT__HAVE_SIGACTION
222 struct evsig_info *sig = &base->sig;
226 * resize saved signal handler array up to the highest signal number.
227 * a dynamic array is used to keep footprint on the low side.
229 if (evsignal >= sig->sh_old_max) {
230 int new_max = evsignal + 1;
231 event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",
232 __func__, evsignal, sig->sh_old_max));
233 p = mm_realloc(sig->sh_old, new_max * sizeof(*sig->sh_old));
235 event_warn("realloc");
239 memset((char *)p + sig->sh_old_max * sizeof(*sig->sh_old),
240 0, (new_max - sig->sh_old_max) * sizeof(*sig->sh_old));
242 sig->sh_old_max = new_max;
246 /* allocate space for previous handler out of dynamic array */
247 sig->sh_old[evsignal] = mm_malloc(sizeof *sig->sh_old[evsignal]);
248 if (sig->sh_old[evsignal] == NULL) {
249 event_warn("malloc");
253 /* save previous handler and setup new handler */
254 #ifdef EVENT__HAVE_SIGACTION
255 memset(&sa, 0, sizeof(sa));
256 sa.sa_handler = handler;
258 sa.sa_flags |= SA_RESTART;
260 sigfillset(&sa.sa_mask);
262 if (sigaction(evsignal, &sa, sig->sh_old[evsignal]) == -1) {
263 event_warn("sigaction");
264 mm_free(sig->sh_old[evsignal]);
265 sig->sh_old[evsignal] = NULL;
269 if ((sh = signal(evsignal, handler)) == SIG_ERR) {
270 event_warn("signal");
271 mm_free(sig->sh_old[evsignal]);
272 sig->sh_old[evsignal] = NULL;
275 *sig->sh_old[evsignal] = sh;
282 evsig_add(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
284 struct evsig_info *sig = &base->sig;
287 EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
289 /* catch signals if they happen quickly */
291 if (evsig_base != base && evsig_base_n_signals_added) {
292 event_warnx("Added a signal to event base %p with signals "
293 "already added to event_base %p. Only one can have "
294 "signals at a time with the %s backend. The base with "
295 "the most recently added signal or the most recent "
296 "event_base_loop() call gets preference; do "
297 "not rely on this behavior in future Libevent versions.",
298 (void *)base, (void *)evsig_base, base->evsel->name);
301 evsig_base_n_signals_added = ++sig->ev_n_signals_added;
302 evsig_base_fd = base->sig.ev_signal_pair[1];
305 event_debug(("%s: %d: changing signal handler", __func__, (int)evsignal));
306 if (evsig_set_handler_(base, (int)evsignal, evsig_handler) == -1) {
311 if (!sig->ev_signal_added) {
312 if (event_add_nolock_(&sig->ev_signal, NULL, 0))
314 sig->ev_signal_added = 1;
321 --evsig_base_n_signals_added;
322 --sig->ev_n_signals_added;
328 evsig_restore_handler_(struct event_base *base, int evsignal)
331 struct evsig_info *sig = &base->sig;
332 #ifdef EVENT__HAVE_SIGACTION
333 struct sigaction *sh;
338 if (evsignal >= sig->sh_old_max) {
339 /* Can't actually restore. */
344 /* restore previous handler */
345 sh = sig->sh_old[evsignal];
346 sig->sh_old[evsignal] = NULL;
347 #ifdef EVENT__HAVE_SIGACTION
348 if (sigaction(evsignal, sh, NULL) == -1) {
349 event_warn("sigaction");
353 if (signal(evsignal, *sh) == SIG_ERR) {
354 event_warn("signal");
365 evsig_del(struct event_base *base, evutil_socket_t evsignal, short old, short events, void *p)
367 EVUTIL_ASSERT(evsignal >= 0 && evsignal < NSIG);
369 event_debug(("%s: "EV_SOCK_FMT": restoring signal handler",
370 __func__, EV_SOCK_ARG(evsignal)));
373 --evsig_base_n_signals_added;
374 --base->sig.ev_n_signals_added;
377 return (evsig_restore_handler_(base, (int)evsignal));
381 evsig_handler(int sig)
383 int save_errno = errno;
385 int socket_errno = EVUTIL_SOCKET_ERROR();
389 if (evsig_base == NULL) {
391 "%s: received signal %d, but have no base configured",
396 #ifndef EVENT__HAVE_SIGACTION
397 signal(sig, evsig_handler);
400 /* Wake up our notification mechanism */
403 send(evsig_base_fd, (char*)&msg, 1, 0);
407 * errno is only set to provide a descriptive message for event_warnx
408 * if write returns 0. Not setting it will result in "No error" message
409 * because write does not set errno when returning 0.
411 * EAGAIN will print "Try again" message. Another idea is to use
412 * ENOSPC, but since we use non blocking sockets EAGAIN is preferable.
414 * Other than setting this text of the logged warning, the value in
415 * errno has no further effect.
418 if (0 >= write(evsig_base_fd, &msg, 1)) {
421 event_warnx("%s: write: %s", __func__, strerror(errno));
428 EVUTIL_SET_SOCKET_ERROR(socket_errno);
433 evsig_dealloc_(struct event_base *base)
436 if (base->sig.ev_signal_added) {
437 event_del(&base->sig.ev_signal);
438 base->sig.ev_signal_added = 0;
440 /* debug event is created in evsig_init_/event_assign even when
441 * ev_signal_added == 0, so unassign is required */
442 event_debug_unassign(&base->sig.ev_signal);
444 for (i = 0; i < NSIG; ++i) {
445 if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
446 evsig_restore_handler_(base, i);
449 if (base == evsig_base) {
451 evsig_base_n_signals_added = 0;
456 if (base->sig.ev_signal_pair[0] != -1) {
457 evutil_closesocket(base->sig.ev_signal_pair[0]);
458 base->sig.ev_signal_pair[0] = -1;
460 if (base->sig.ev_signal_pair[1] != -1) {
461 evutil_closesocket(base->sig.ev_signal_pair[1]);
462 base->sig.ev_signal_pair[1] = -1;
464 base->sig.sh_old_max = 0;
466 /* per index frees are handled in evsig_del() */
467 if (base->sig.sh_old) {
468 mm_free(base->sig.sh_old);
469 base->sig.sh_old = NULL;
474 evsig_free_globals_locks(void)
476 #ifndef EVENT__DISABLE_THREAD_SUPPORT
477 if (evsig_base_lock != NULL) {
478 EVTHREAD_FREE_LOCK(evsig_base_lock, 0);
479 evsig_base_lock = NULL;
486 evsig_free_globals_(void)
488 evsig_free_globals_locks();
491 #ifndef EVENT__DISABLE_THREAD_SUPPORT
493 evsig_global_setup_locks_(const int enable_locks)
495 EVTHREAD_SETUP_GLOBAL_LOCK(evsig_base_lock, 0);