Annotation of embedaddon/libevent/signal.c, revision 1.1.1.1
1.1 misho 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:
66: struct event_base *evsignal_base = NULL;
67:
68: static void evsignal_handler(int sig);
69:
70: /* Callback for when the signal handler write a byte to our signaling socket */
71: static void
72: evsignal_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:
95: int
96: evsignal_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. */
139: int
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: sig->sh_old[evsignal] = NULL;
190: return (-1);
191: }
192: #else
193: if ((sh = signal(evsignal, handler)) == SIG_ERR) {
194: event_warn("signal");
195: free(sig->sh_old[evsignal]);
196: sig->sh_old[evsignal] = NULL;
197: return (-1);
198: }
199: *sig->sh_old[evsignal] = sh;
200: #endif
201:
202: return (0);
203: }
204:
205: int
206: evsignal_add(struct event *ev)
207: {
208: int evsignal;
209: struct event_base *base = ev->ev_base;
210: struct evsignal_info *sig = &ev->ev_base->sig;
211:
212: if (ev->ev_events & (EV_READ|EV_WRITE))
213: event_errx(1, "%s: EV_SIGNAL incompatible use", __func__);
214: evsignal = EVENT_SIGNAL(ev);
215: assert(evsignal >= 0 && evsignal < NSIG);
216: if (TAILQ_EMPTY(&sig->evsigevents[evsignal])) {
217: event_debug(("%s: %p: changing signal handler", __func__, ev));
218: if (_evsignal_set_handler(
219: base, evsignal, evsignal_handler) == -1)
220: return (-1);
221:
222: /* catch signals if they happen quickly */
223: evsignal_base = base;
224:
225: if (!sig->ev_signal_added) {
226: if (event_add(&sig->ev_signal, NULL))
227: return (-1);
228: sig->ev_signal_added = 1;
229: }
230: }
231:
232: /* multiple events may listen to the same signal */
233: TAILQ_INSERT_TAIL(&sig->evsigevents[evsignal], ev, ev_signal_next);
234:
235: return (0);
236: }
237:
238: int
239: _evsignal_restore_handler(struct event_base *base, int evsignal)
240: {
241: int ret = 0;
242: struct evsignal_info *sig = &base->sig;
243: #ifdef HAVE_SIGACTION
244: struct sigaction *sh;
245: #else
246: ev_sighandler_t *sh;
247: #endif
248:
249: /* restore previous handler */
250: sh = sig->sh_old[evsignal];
251: sig->sh_old[evsignal] = NULL;
252: #ifdef HAVE_SIGACTION
253: if (sigaction(evsignal, sh, NULL) == -1) {
254: event_warn("sigaction");
255: ret = -1;
256: }
257: #else
258: if (signal(evsignal, *sh) == SIG_ERR) {
259: event_warn("signal");
260: ret = -1;
261: }
262: #endif
263: free(sh);
264:
265: return ret;
266: }
267:
268: int
269: evsignal_del(struct event *ev)
270: {
271: struct event_base *base = ev->ev_base;
272: struct evsignal_info *sig = &base->sig;
273: int evsignal = EVENT_SIGNAL(ev);
274:
275: assert(evsignal >= 0 && evsignal < NSIG);
276:
277: /* multiple events may listen to the same signal */
278: TAILQ_REMOVE(&sig->evsigevents[evsignal], ev, ev_signal_next);
279:
280: if (!TAILQ_EMPTY(&sig->evsigevents[evsignal]))
281: return (0);
282:
283: event_debug(("%s: %p: restoring signal handler", __func__, ev));
284:
285: return (_evsignal_restore_handler(ev->ev_base, EVENT_SIGNAL(ev)));
286: }
287:
288: static void
289: evsignal_handler(int sig)
290: {
291: int save_errno = errno;
292:
293: if (evsignal_base == NULL) {
294: event_warn(
295: "%s: received signal %d, but have no base configured",
296: __func__, sig);
297: return;
298: }
299:
300: evsignal_base->sig.evsigcaught[sig]++;
301: evsignal_base->sig.evsignal_caught = 1;
302:
303: #ifndef HAVE_SIGACTION
304: signal(sig, evsignal_handler);
305: #endif
306:
307: /* Wake up our notification mechanism */
308: send(evsignal_base->sig.ev_signal_pair[0], "a", 1, 0);
309: errno = save_errno;
310: }
311:
312: void
313: evsignal_process(struct event_base *base)
314: {
315: struct evsignal_info *sig = &base->sig;
316: struct event *ev, *next_ev;
317: sig_atomic_t ncalls;
318: int i;
319:
320: base->sig.evsignal_caught = 0;
321: for (i = 1; i < NSIG; ++i) {
322: ncalls = sig->evsigcaught[i];
323: if (ncalls == 0)
324: continue;
325: sig->evsigcaught[i] -= ncalls;
326:
327: for (ev = TAILQ_FIRST(&sig->evsigevents[i]);
328: ev != NULL; ev = next_ev) {
329: next_ev = TAILQ_NEXT(ev, ev_signal_next);
330: if (!(ev->ev_events & EV_PERSIST))
331: event_del(ev);
332: event_active(ev, EV_SIGNAL, ncalls);
333: }
334:
335: }
336: }
337:
338: void
339: evsignal_dealloc(struct event_base *base)
340: {
341: int i = 0;
342: if (base->sig.ev_signal_added) {
343: event_del(&base->sig.ev_signal);
344: base->sig.ev_signal_added = 0;
345: }
346: for (i = 0; i < NSIG; ++i) {
347: if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
348: _evsignal_restore_handler(base, i);
349: }
350:
351: if (base->sig.ev_signal_pair[0] != -1) {
352: EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[0]);
353: base->sig.ev_signal_pair[0] = -1;
354: }
355: if (base->sig.ev_signal_pair[1] != -1) {
356: EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[1]);
357: base->sig.ev_signal_pair[1] = -1;
358: }
359: base->sig.sh_old_max = 0;
360:
361: /* per index frees are handled in evsig_del() */
362: if (base->sig.sh_old) {
363: free(base->sig.sh_old);
364: base->sig.sh_old = NULL;
365: }
366: }
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