1/*	$OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $	*/
2
3/*
4 * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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.
17 *
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.
28 */
29#ifdef HAVE_CONFIG_H
30#include "config.h"
31#endif
32
33#ifdef WIN32
34#define WIN32_LEAN_AND_MEAN
35#include <winsock2.h>
36#include <windows.h>
37#undef WIN32_LEAN_AND_MEAN
38#endif
39#include <sys/types.h>
40#ifdef HAVE_SYS_TIME_H
41#include <sys/time.h>
42#endif
43#include <sys/queue.h>
44#ifdef HAVE_SYS_SOCKET_H
45#include <sys/socket.h>
46#endif
47#include <signal.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include <string.h>
51#ifdef HAVE_UNISTD_H
52#include <unistd.h>
53#endif
54#include <errno.h>
55#ifdef HAVE_FCNTL_H
56#include <fcntl.h>
57#endif
58#include <assert.h>
59
60#include "event.h"
61#include "event-internal.h"
62#include "evsignal.h"
63#include "evutil.h"
64#include "log.h"
65
66struct event_base *evsignal_base = NULL;
67
68static void evsignal_handler(int sig);
69
70/* Callback for when the signal handler write a byte to our signaling socket */
71static void
72evsignal_cb(int fd, short what, void *arg)
73{
74	static char signals[1];
75#ifdef WIN32
76	SSIZE_T n;
77#else
78	ssize_t n;
79#endif
80
81	n = recv(fd, signals, sizeof(signals), 0);
82	if (n == -1)
83		event_err(1, "%s: read", __func__);
84}
85
86#ifdef HAVE_SETFD
87#define FD_CLOSEONEXEC(x) do { \
88        if (fcntl(x, F_SETFD, 1) == -1) \
89                event_warn("fcntl(%d, F_SETFD)", x); \
90} while (0)
91#else
92#define FD_CLOSEONEXEC(x)
93#endif
94
95int
96evsignal_init(struct event_base *base)
97{
98	int i;
99
100	/*
101	 * Our signal handler is going to write to one end of the socket
102	 * pair to wake up our event loop.  The event loop then scans for
103	 * signals that got delivered.
104	 */
105	if (evutil_socketpair(
106		    AF_UNIX, SOCK_STREAM, 0, base->sig.ev_signal_pair) == -1) {
107#ifdef WIN32
108		/* Make this nonfatal on win32, where sometimes people
109		   have localhost firewalled. */
110		event_warn("%s: socketpair", __func__);
111#else
112		event_err(1, "%s: socketpair", __func__);
113#endif
114		return -1;
115	}
116
117	FD_CLOSEONEXEC(base->sig.ev_signal_pair[0]);
118	FD_CLOSEONEXEC(base->sig.ev_signal_pair[1]);
119	base->sig.sh_old = NULL;
120	base->sig.sh_old_max = 0;
121	base->sig.evsignal_caught = 0;
122	memset(&base->sig.evsigcaught, 0, sizeof(sig_atomic_t)*NSIG);
123	/* initialize the queues for all events */
124	for (i = 0; i < NSIG; ++i)
125		TAILQ_INIT(&base->sig.evsigevents[i]);
126
127        evutil_make_socket_nonblocking(base->sig.ev_signal_pair[0]);
128
129	event_set(&base->sig.ev_signal, base->sig.ev_signal_pair[1],
130		EV_READ | EV_PERSIST, evsignal_cb, &base->sig.ev_signal);
131	base->sig.ev_signal.ev_base = base;
132	base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL;
133
134	return 0;
135}
136
137/* Helper: set the signal handler for evsignal to handler in base, so that
138 * we can restore the original handler when we clear the current one. */
139int
140_evsignal_set_handler(struct event_base *base,
141		      int evsignal, void (*handler)(int))
142{
143#ifdef HAVE_SIGACTION
144	struct sigaction sa;
145#else
146	ev_sighandler_t sh;
147#endif
148	struct evsignal_info *sig = &base->sig;
149	void *p;
150
151	/*
152	 * resize saved signal handler array up to the highest signal number.
153	 * a dynamic array is used to keep footprint on the low side.
154	 */
155	if (evsignal >= sig->sh_old_max) {
156		int new_max = evsignal + 1;
157		event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",
158			    __func__, evsignal, sig->sh_old_max));
159		p = realloc(sig->sh_old, new_max * sizeof(*sig->sh_old));
160		if (p == NULL) {
161			event_warn("realloc");
162			return (-1);
163		}
164
165		memset((char *)p + sig->sh_old_max * sizeof(*sig->sh_old),
166		    0, (new_max - sig->sh_old_max) * sizeof(*sig->sh_old));
167
168		sig->sh_old_max = new_max;
169		sig->sh_old = p;
170	}
171
172	/* allocate space for previous handler out of dynamic array */
173	sig->sh_old[evsignal] = malloc(sizeof *sig->sh_old[evsignal]);
174	if (sig->sh_old[evsignal] == NULL) {
175		event_warn("malloc");
176		return (-1);
177	}
178
179	/* save previous handler and setup new handler */
180#ifdef HAVE_SIGACTION
181	memset(&sa, 0, sizeof(sa));
182	sa.sa_handler = handler;
183	sa.sa_flags |= SA_RESTART;
184	sigfillset(&sa.sa_mask);
185
186	if (sigaction(evsignal, &sa, sig->sh_old[evsignal]) == -1) {
187		event_warn("sigaction");
188		free(sig->sh_old[evsignal]);
189		return (-1);
190	}
191#else
192	if ((sh = signal(evsignal, handler)) == SIG_ERR) {
193		event_warn("signal");
194		free(sig->sh_old[evsignal]);
195		return (-1);
196	}
197	*sig->sh_old[evsignal] = sh;
198#endif
199
200	return (0);
201}
202
203int
204evsignal_add(struct event *ev)
205{
206	int evsignal;
207	struct event_base *base = ev->ev_base;
208	struct evsignal_info *sig = &ev->ev_base->sig;
209
210	if (ev->ev_events & (EV_READ|EV_WRITE))
211		event_errx(1, "%s: EV_SIGNAL incompatible use", __func__);
212	evsignal = EVENT_SIGNAL(ev);
213	assert(evsignal >= 0 && evsignal < NSIG);
214	if (TAILQ_EMPTY(&sig->evsigevents[evsignal])) {
215		event_debug(("%s: %p: changing signal handler", __func__, ev));
216		if (_evsignal_set_handler(
217			    base, evsignal, evsignal_handler) == -1)
218			return (-1);
219
220		/* catch signals if they happen quickly */
221		evsignal_base = base;
222
223		if (!sig->ev_signal_added) {
224			if (event_add(&sig->ev_signal, NULL))
225				return (-1);
226			sig->ev_signal_added = 1;
227		}
228	}
229
230	/* multiple events may listen to the same signal */
231	TAILQ_INSERT_TAIL(&sig->evsigevents[evsignal], ev, ev_signal_next);
232
233	return (0);
234}
235
236int
237_evsignal_restore_handler(struct event_base *base, int evsignal)
238{
239	int ret = 0;
240	struct evsignal_info *sig = &base->sig;
241#ifdef HAVE_SIGACTION
242	struct sigaction *sh;
243#else
244	ev_sighandler_t *sh;
245#endif
246
247	/* restore previous handler */
248	sh = sig->sh_old[evsignal];
249	sig->sh_old[evsignal] = NULL;
250#ifdef HAVE_SIGACTION
251	if (sigaction(evsignal, sh, NULL) == -1) {
252		event_warn("sigaction");
253		ret = -1;
254	}
255#else
256	if (signal(evsignal, *sh) == SIG_ERR) {
257		event_warn("signal");
258		ret = -1;
259	}
260#endif
261	free(sh);
262
263	return ret;
264}
265
266int
267evsignal_del(struct event *ev)
268{
269	struct event_base *base = ev->ev_base;
270	struct evsignal_info *sig = &base->sig;
271	int evsignal = EVENT_SIGNAL(ev);
272
273	assert(evsignal >= 0 && evsignal < NSIG);
274
275	/* multiple events may listen to the same signal */
276	TAILQ_REMOVE(&sig->evsigevents[evsignal], ev, ev_signal_next);
277
278	if (!TAILQ_EMPTY(&sig->evsigevents[evsignal]))
279		return (0);
280
281	event_debug(("%s: %p: restoring signal handler", __func__, ev));
282
283	return (_evsignal_restore_handler(ev->ev_base, EVENT_SIGNAL(ev)));
284}
285
286static void
287evsignal_handler(int sig)
288{
289	int save_errno = errno;
290
291	if (evsignal_base == NULL) {
292		event_warn(
293			"%s: received signal %d, but have no base configured",
294			__func__, sig);
295		return;
296	}
297
298	evsignal_base->sig.evsigcaught[sig]++;
299	evsignal_base->sig.evsignal_caught = 1;
300
301#ifndef HAVE_SIGACTION
302	signal(sig, evsignal_handler);
303#endif
304
305	/* Wake up our notification mechanism */
306	send(evsignal_base->sig.ev_signal_pair[0], "a", 1, 0);
307	errno = save_errno;
308}
309
310void
311evsignal_process(struct event_base *base)
312{
313	struct evsignal_info *sig = &base->sig;
314	struct event *ev, *next_ev;
315	sig_atomic_t ncalls;
316	int i;
317
318	base->sig.evsignal_caught = 0;
319	for (i = 1; i < NSIG; ++i) {
320		ncalls = sig->evsigcaught[i];
321		if (ncalls == 0)
322			continue;
323		sig->evsigcaught[i] -= ncalls;
324
325		for (ev = TAILQ_FIRST(&sig->evsigevents[i]);
326		    ev != NULL; ev = next_ev) {
327			next_ev = TAILQ_NEXT(ev, ev_signal_next);
328			if (!(ev->ev_events & EV_PERSIST))
329				event_del(ev);
330			event_active(ev, EV_SIGNAL, ncalls);
331		}
332
333	}
334}
335
336void
337evsignal_dealloc(struct event_base *base)
338{
339	int i = 0;
340	if (base->sig.ev_signal_added) {
341		event_del(&base->sig.ev_signal);
342		base->sig.ev_signal_added = 0;
343	}
344	for (i = 0; i < NSIG; ++i) {
345		if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
346			_evsignal_restore_handler(base, i);
347	}
348
349	EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[0]);
350	base->sig.ev_signal_pair[0] = -1;
351	EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[1]);
352	base->sig.ev_signal_pair[1] = -1;
353	base->sig.sh_old_max = 0;
354
355	/* per index frees are handled in evsignal_del() */
356	free(base->sig.sh_old);
357}
358