Annotation of embedaddon/libevent/signal.c, revision 1.1.1.1.2.1
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:
1.1.1.1.2.1! misho 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:
1.1 misho 77: /* Callback for when the signal handler write a byte to our signaling socket */
78: static void
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);
1.1.1.1.2.1! misho 89: if (n == -1) {
! 90: int err = EVUTIL_SOCKET_ERROR();
! 91: if (! error_is_eagain(err))
! 92: event_err(1, "%s: read", __func__);
! 93: }
1.1 misho 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
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]);
1.1.1.1.2.1! misho 138: evutil_make_socket_nonblocking(base->sig.ev_signal_pair[1]);
1.1 misho 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
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
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
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
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
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
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
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: }
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