1 /* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
2
3 /*
4 * Copyright 2000-2002 Niels Provos <[email protected]>
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
66 struct event_base *evsignal_base = NULL;
67
68 static void evsignal_handler(int sig);
69
70 #ifdef WIN32
71 #define error_is_eagain(err) \
72 ((err) == EAGAIN || (err) == WSAEWOULDBLOCK)
73 #else
74 #define error_is_eagain(err) ((err) == EAGAIN)
75 #endif
76
77 /* Callback for when the signal handler write a byte to our signaling socket */
78 static void
evsignal_cb(int fd,short what,void * arg)79 evsignal_cb(int fd, short what, void *arg)
80 {
81 static char signals[1];
82 #ifdef WIN32
83 SSIZE_T n;
84 #else
85 ssize_t n;
86 #endif
87
88 n = recv(fd, signals, sizeof(signals), 0);
89 if (n == -1) {
90 int err = EVUTIL_SOCKET_ERROR();
91 if (! error_is_eagain(err))
92 event_err(1, "%s: read", __func__);
93 }
94 }
95
96 #ifdef HAVE_SETFD
97 #define FD_CLOSEONEXEC(x) do { \
98 if (fcntl(x, F_SETFD, 1) == -1) \
99 event_warn("fcntl(%d, F_SETFD)", x); \
100 } while (0)
101 #else
102 #define FD_CLOSEONEXEC(x)
103 #endif
104
105 int
evsignal_init(struct event_base * base)106 evsignal_init(struct event_base *base)
107 {
108 int i;
109
110 /*
111 * Our signal handler is going to write to one end of the socket
112 * pair to wake up our event loop. The event loop then scans for
113 * signals that got delivered.
114 */
115 if (evutil_socketpair(
116 AF_UNIX, SOCK_STREAM, 0, base->sig.ev_signal_pair) == -1) {
117 #ifdef WIN32
118 /* Make this nonfatal on win32, where sometimes people
119 have localhost firewalled. */
120 event_warn("%s: socketpair", __func__);
121 #else
122 event_err(1, "%s: socketpair", __func__);
123 #endif
124 return -1;
125 }
126
127 FD_CLOSEONEXEC(base->sig.ev_signal_pair[0]);
128 FD_CLOSEONEXEC(base->sig.ev_signal_pair[1]);
129 base->sig.sh_old = NULL;
130 base->sig.sh_old_max = 0;
131 base->sig.evsignal_caught = 0;
132 memset(&base->sig.evsigcaught, 0, sizeof(sig_atomic_t)*NSIG);
133 /* initialize the queues for all events */
134 for (i = 0; i < NSIG; ++i)
135 TAILQ_INIT(&base->sig.evsigevents[i]);
136
137 evutil_make_socket_nonblocking(base->sig.ev_signal_pair[0]);
138 evutil_make_socket_nonblocking(base->sig.ev_signal_pair[1]);
139
140 event_set(&base->sig.ev_signal, base->sig.ev_signal_pair[1],
141 EV_READ | EV_PERSIST, evsignal_cb, &base->sig.ev_signal);
142 base->sig.ev_signal.ev_base = base;
143 base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL;
144
145 return 0;
146 }
147
148 /* Helper: set the signal handler for evsignal to handler in base, so that
149 * we can restore the original handler when we clear the current one. */
150 int
_evsignal_set_handler(struct event_base * base,int evsignal,void (* handler)(int))151 _evsignal_set_handler(struct event_base *base,
152 int evsignal, void (*handler)(int))
153 {
154 #ifdef HAVE_SIGACTION
155 struct sigaction sa;
156 #else
157 ev_sighandler_t sh;
158 #endif
159 struct evsignal_info *sig = &base->sig;
160 void *p;
161
162 /*
163 * resize saved signal handler array up to the highest signal number.
164 * a dynamic array is used to keep footprint on the low side.
165 */
166 if (evsignal >= sig->sh_old_max) {
167 int new_max = evsignal + 1;
168 event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",
169 __func__, evsignal, sig->sh_old_max));
170 p = realloc(sig->sh_old, new_max * sizeof(*sig->sh_old));
171 if (p == NULL) {
172 event_warn("realloc");
173 return (-1);
174 }
175
176 memset((char *)p + sig->sh_old_max * sizeof(*sig->sh_old),
177 0, (new_max - sig->sh_old_max) * sizeof(*sig->sh_old));
178
179 sig->sh_old_max = new_max;
180 sig->sh_old = p;
181 }
182
183 /* allocate space for previous handler out of dynamic array */
184 sig->sh_old[evsignal] = malloc(sizeof *sig->sh_old[evsignal]);
185 if (sig->sh_old[evsignal] == NULL) {
186 event_warn("malloc");
187 return (-1);
188 }
189
190 /* save previous handler and setup new handler */
191 #ifdef HAVE_SIGACTION
192 memset(&sa, 0, sizeof(sa));
193 sa.sa_handler = handler;
194 sa.sa_flags |= SA_RESTART;
195 sigfillset(&sa.sa_mask);
196
197 if (sigaction(evsignal, &sa, sig->sh_old[evsignal]) == -1) {
198 event_warn("sigaction");
199 free(sig->sh_old[evsignal]);
200 sig->sh_old[evsignal] = NULL;
201 return (-1);
202 }
203 #else
204 if ((sh = signal(evsignal, handler)) == SIG_ERR) {
205 event_warn("signal");
206 free(sig->sh_old[evsignal]);
207 sig->sh_old[evsignal] = NULL;
208 return (-1);
209 }
210 *sig->sh_old[evsignal] = sh;
211 #endif
212
213 return (0);
214 }
215
216 int
evsignal_add(struct event * ev)217 evsignal_add(struct event *ev)
218 {
219 int evsignal;
220 struct event_base *base = ev->ev_base;
221 struct evsignal_info *sig = &ev->ev_base->sig;
222
223 if (ev->ev_events & (EV_READ|EV_WRITE))
224 event_errx(1, "%s: EV_SIGNAL incompatible use", __func__);
225 evsignal = EVENT_SIGNAL(ev);
226 assert(evsignal >= 0 && evsignal < NSIG);
227 if (TAILQ_EMPTY(&sig->evsigevents[evsignal])) {
228 event_debug(("%s: %p: changing signal handler", __func__, ev));
229 if (_evsignal_set_handler(
230 base, evsignal, evsignal_handler) == -1)
231 return (-1);
232
233 /* catch signals if they happen quickly */
234 evsignal_base = base;
235
236 if (!sig->ev_signal_added) {
237 if (event_add(&sig->ev_signal, NULL))
238 return (-1);
239 sig->ev_signal_added = 1;
240 }
241 }
242
243 /* multiple events may listen to the same signal */
244 TAILQ_INSERT_TAIL(&sig->evsigevents[evsignal], ev, ev_signal_next);
245
246 return (0);
247 }
248
249 int
_evsignal_restore_handler(struct event_base * base,int evsignal)250 _evsignal_restore_handler(struct event_base *base, int evsignal)
251 {
252 int ret = 0;
253 struct evsignal_info *sig = &base->sig;
254 #ifdef HAVE_SIGACTION
255 struct sigaction *sh;
256 #else
257 ev_sighandler_t *sh;
258 #endif
259
260 /* restore previous handler */
261 sh = sig->sh_old[evsignal];
262 sig->sh_old[evsignal] = NULL;
263 #ifdef HAVE_SIGACTION
264 if (sigaction(evsignal, sh, NULL) == -1) {
265 event_warn("sigaction");
266 ret = -1;
267 }
268 #else
269 if (signal(evsignal, *sh) == SIG_ERR) {
270 event_warn("signal");
271 ret = -1;
272 }
273 #endif
274 free(sh);
275
276 return ret;
277 }
278
279 int
evsignal_del(struct event * ev)280 evsignal_del(struct event *ev)
281 {
282 struct event_base *base = ev->ev_base;
283 struct evsignal_info *sig = &base->sig;
284 int evsignal = EVENT_SIGNAL(ev);
285
286 assert(evsignal >= 0 && evsignal < NSIG);
287
288 /* multiple events may listen to the same signal */
289 TAILQ_REMOVE(&sig->evsigevents[evsignal], ev, ev_signal_next);
290
291 if (!TAILQ_EMPTY(&sig->evsigevents[evsignal]))
292 return (0);
293
294 event_debug(("%s: %p: restoring signal handler", __func__, ev));
295
296 return (_evsignal_restore_handler(ev->ev_base, EVENT_SIGNAL(ev)));
297 }
298
299 static void
evsignal_handler(int sig)300 evsignal_handler(int sig)
301 {
302 int save_errno = errno;
303
304 if (evsignal_base == NULL) {
305 event_warn(
306 "%s: received signal %d, but have no base configured",
307 __func__, sig);
308 return;
309 }
310
311 evsignal_base->sig.evsigcaught[sig]++;
312 evsignal_base->sig.evsignal_caught = 1;
313
314 #ifndef HAVE_SIGACTION
315 signal(sig, evsignal_handler);
316 #endif
317
318 /* Wake up our notification mechanism */
319 send(evsignal_base->sig.ev_signal_pair[0], "a", 1, 0);
320 errno = save_errno;
321 }
322
323 void
evsignal_process(struct event_base * base)324 evsignal_process(struct event_base *base)
325 {
326 struct evsignal_info *sig = &base->sig;
327 struct event *ev, *next_ev;
328 sig_atomic_t ncalls;
329 int i;
330
331 base->sig.evsignal_caught = 0;
332 for (i = 1; i < NSIG; ++i) {
333 ncalls = sig->evsigcaught[i];
334 if (ncalls == 0)
335 continue;
336 sig->evsigcaught[i] -= ncalls;
337
338 for (ev = TAILQ_FIRST(&sig->evsigevents[i]);
339 ev != NULL; ev = next_ev) {
340 next_ev = TAILQ_NEXT(ev, ev_signal_next);
341 if (!(ev->ev_events & EV_PERSIST))
342 event_del(ev);
343 event_active(ev, EV_SIGNAL, ncalls);
344 }
345
346 }
347 }
348
349 void
evsignal_dealloc(struct event_base * base)350 evsignal_dealloc(struct event_base *base)
351 {
352 int i = 0;
353 if (base->sig.ev_signal_added) {
354 event_del(&base->sig.ev_signal);
355 base->sig.ev_signal_added = 0;
356 }
357 for (i = 0; i < NSIG; ++i) {
358 if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
359 _evsignal_restore_handler(base, i);
360 }
361
362 if (base->sig.ev_signal_pair[0] != -1) {
363 EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[0]);
364 base->sig.ev_signal_pair[0] = -1;
365 }
366 if (base->sig.ev_signal_pair[1] != -1) {
367 EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[1]);
368 base->sig.ev_signal_pair[1] = -1;
369 }
370 base->sig.sh_old_max = 0;
371
372 /* per index frees are handled in evsig_del() */
373 if (base->sig.sh_old) {
374 free(base->sig.sh_old);
375 base->sig.sh_old = NULL;
376 }
377 }
378