external/bsd/libevent/dist/signal.c

   1 /*      $NetBSD$        */
   2 /*      $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $       */
   3
   4 /*
   5  * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30 #ifdef HAVE_CONFIG_H
  31 #include "config.h"
  32 #endif
  33
  34 #ifdef WIN32
  35 #define WIN32_LEAN_AND_MEAN
  36 #include <winsock2.h>
  37 #include <windows.h>
  38 #undef WIN32_LEAN_AND_MEAN
  39 #endif
  40 #include <sys/types.h>
  41 #ifdef HAVE_SYS_TIME_H
  42 #include <sys/time.h>
  43 #endif
  44 #include <sys/queue.h>
  45 #ifdef HAVE_SYS_SOCKET_H
  46 #include <sys/socket.h>
  47 #endif
  48 #include <signal.h>
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <string.h>
  52 #ifdef HAVE_UNISTD_H
  53 #include <unistd.h>
  54 #endif
  55 #include <errno.h>
  56 #ifdef HAVE_FCNTL_H
  57 #include <fcntl.h>
  58 #endif
  59 #include <assert.h>
  60
  61 #include "event.h"
  62 #include "event-internal.h"
  63 #include "evsignal.h"
  64 #include "evutil.h"
  65 #include "log.h"
  66
  67 struct event_base *evsignal_base = NULL;
  68
  69 static void evsignal_handler(int sig);
  70
  71 /* Callback for when the signal handler write a byte to our signaling socket */
  72 static void
  73 evsignal_cb(int fd, short what, void *arg)
  74 {
  75         static char signals[1];
  76 #ifdef WIN32
  77         SSIZE_T n;
  78 #else
  79         ssize_t n;
  80 #endif
  81
  82         n = recv(fd, signals, sizeof(signals), 0);
  83         if (n == -1)
  84                 event_err(1, "%s: read", __func__);
  85 }
  86
  87 #ifdef HAVE_SETFD
  88 #define FD_CLOSEONEXEC(x) do { \
  89         if (fcntl(x, F_SETFD, 1) == -1) \
  90                 event_warn("fcntl(%d, F_SETFD)", x); \
  91 } while (0)
  92 #else
  93 #define FD_CLOSEONEXEC(x)
  94 #endif
  95
  96 int
  97 evsignal_init(struct event_base *base)
  98 {
  99         int i;
 100
 101         /*
 102          * Our signal handler is going to write to one end of the socket
 103          * pair to wake up our event loop.  The event loop then scans for
 104          * signals that got delivered.
 105          */
 106         if (evutil_socketpair(
 107                     AF_UNIX, SOCK_STREAM, 0, base->sig.ev_signal_pair) == -1) {
 108 #ifdef WIN32
 109                 /* Make this nonfatal on win32, where sometimes people
 110                    have localhost firewalled. */
 111                 event_warn("%s: socketpair", __func__);
 112 #else
 113                 event_err(1, "%s: socketpair", __func__);
 114 #endif
 115                 return -1;
 116         }
 117
 118         FD_CLOSEONEXEC(base->sig.ev_signal_pair[0]);
 119         FD_CLOSEONEXEC(base->sig.ev_signal_pair[1]);
 120         base->sig.sh_old = NULL;
 121         base->sig.sh_old_max = 0;
 122         base->sig.evsignal_caught = 0;
 123         memset(&base->sig.evsigcaught, 0, sizeof(sig_atomic_t)*NSIG);
 124         /* initialize the queues for all events */
 125         for (i = 0; i < NSIG; ++i)
 126                 TAILQ_INIT(&base->sig.evsigevents[i]);
 127
 128         evutil_make_socket_nonblocking(base->sig.ev_signal_pair[0]);
 129
 130         event_set(&base->sig.ev_signal, base->sig.ev_signal_pair[1],
 131                 EV_READ | EV_PERSIST, evsignal_cb, &base->sig.ev_signal);
 132         base->sig.ev_signal.ev_base = base;
 133         base->sig.ev_signal.ev_flags |= EVLIST_INTERNAL;
 134
 135         return 0;
 136 }
 137
 138 /* Helper: set the signal handler for evsignal to handler in base, so that
 139  * we can restore the original handler when we clear the current one. */
 140 int
 141 _evsignal_set_handler(struct event_base *base,
 142                       int evsignal, void (*handler)(int))
 143 {
 144 #ifdef HAVE_SIGACTION
 145         struct sigaction sa;
 146 #else
 147         ev_sighandler_t sh;
 148 #endif
 149         struct evsignal_info *sig = &base->sig;
 150         void *p;
 151
 152         /*
 153          * resize saved signal handler array up to the highest signal number.
 154          * a dynamic array is used to keep footprint on the low side.
 155          */
 156         if (evsignal >= sig->sh_old_max) {
 157                 int new_max = evsignal + 1;
 158                 event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",
 159                             __func__, evsignal, sig->sh_old_max));
 160                 p = realloc(sig->sh_old, new_max * sizeof(*sig->sh_old));
 161                 if (p == NULL) {
 162                         event_warn("realloc");
 163                         return (-1);
 164                 }
 165
 166                 memset((char *)p + sig->sh_old_max * sizeof(*sig->sh_old),
 167                     0, (new_max - sig->sh_old_max) * sizeof(*sig->sh_old));
 168
 169                 sig->sh_old_max = new_max;
 170                 sig->sh_old = p;
 171         }
 172
 173         /* allocate space for previous handler out of dynamic array */
 174         sig->sh_old[evsignal] = malloc(sizeof *sig->sh_old[evsignal]);
 175         if (sig->sh_old[evsignal] == NULL) {
 176                 event_warn("malloc");
 177                 return (-1);
 178         }
 179
 180         /* save previous handler and setup new handler */
 181 #ifdef HAVE_SIGACTION
 182         memset(&sa, 0, sizeof(sa));
 183         sa.sa_handler = handler;
 184         sa.sa_flags |= SA_RESTART;
 185         sigfillset(&sa.sa_mask);
 186
 187         if (sigaction(evsignal, &sa, sig->sh_old[evsignal]) == -1) {
 188                 event_warn("sigaction");
 189                 free(sig->sh_old[evsignal]);
 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                 return (-1);
 197         }
 198         *sig->sh_old[evsignal] = sh;
 199 #endif
 200
 201         return (0);
 202 }
 203
 204 int
 205 evsignal_add(struct event *ev)
 206 {
 207         int evsignal;
 208         struct event_base *base = ev->ev_base;
 209         struct evsignal_info *sig = &ev->ev_base->sig;
 210
 211         if (ev->ev_events & (EV_READ|EV_WRITE))
 212                 event_errx(1, "%s: EV_SIGNAL incompatible use", __func__);
 213         evsignal = EVENT_SIGNAL(ev);
 214         assert(evsignal >= 0 && evsignal < NSIG);
 215         if (TAILQ_EMPTY(&sig->evsigevents[evsignal])) {
 216                 event_debug(("%s: %p: changing signal handler", __func__, ev));
 217                 if (_evsignal_set_handler(
 218                             base, evsignal, evsignal_handler) == -1)
 219                         return (-1);
 220
 221                 /* catch signals if they happen quickly */
 222                 evsignal_base = base;
 223
 224                 if (!sig->ev_signal_added) {
 225                         if (event_add(&sig->ev_signal, NULL))
 226                                 return (-1);
 227                         sig->ev_signal_added = 1;
 228                 }
 229         }
 230
 231         /* multiple events may listen to the same signal */
 232         TAILQ_INSERT_TAIL(&sig->evsigevents[evsignal], ev, ev_signal_next);
 233
 234         return (0);
 235 }
 236
 237 int
 238 _evsignal_restore_handler(struct event_base *base, int evsignal)
 239 {
 240         int ret = 0;
 241         struct evsignal_info *sig = &base->sig;
 242 #ifdef HAVE_SIGACTION
 243         struct sigaction *sh;
 244 #else
 245         ev_sighandler_t *sh;
 246 #endif
 247
 248         /* restore previous handler */
 249         sh = sig->sh_old[evsignal];
 250         sig->sh_old[evsignal] = NULL;
 251 #ifdef HAVE_SIGACTION
 252         if (sigaction(evsignal, sh, NULL) == -1) {
 253                 event_warn("sigaction");
 254                 ret = -1;
 255         }
 256 #else
 257         if (signal(evsignal, *sh) == SIG_ERR) {
 258                 event_warn("signal");
 259                 ret = -1;
 260         }
 261 #endif
 262         free(sh);
 263
 264         return ret;
 265 }
 266
 267 int
 268 evsignal_del(struct event *ev)
 269 {
 270         struct event_base *base = ev->ev_base;
 271         struct evsignal_info *sig = &base->sig;
 272         int evsignal = EVENT_SIGNAL(ev);
 273
 274         assert(evsignal >= 0 && evsignal < NSIG);
 275
 276         /* multiple events may listen to the same signal */
 277         TAILQ_REMOVE(&sig->evsigevents[evsignal], ev, ev_signal_next);
 278
 279         if (!TAILQ_EMPTY(&sig->evsigevents[evsignal]))
 280                 return (0);
 281
 282         event_debug(("%s: %p: restoring signal handler", __func__, ev));
 283
 284         return (_evsignal_restore_handler(ev->ev_base, EVENT_SIGNAL(ev)));
 285 }
 286
 287 static void
 288 evsignal_handler(int sig)
 289 {
 290         int save_errno = errno;
 291
 292         if (evsignal_base == NULL) {
 293                 event_warn(
 294                         "%s: received signal %d, but have no base configured",
 295                         __func__, sig);
 296                 return;
 297         }
 298
 299         evsignal_base->sig.evsigcaught[sig]++;
 300         evsignal_base->sig.evsignal_caught = 1;
 301
 302 #ifndef HAVE_SIGACTION
 303         signal(sig, evsignal_handler);
 304 #endif
 305
 306         /* Wake up our notification mechanism */
 307         send(evsignal_base->sig.ev_signal_pair[0], "a", 1, 0);
 308         errno = save_errno;
 309 }
 310
 311 void
 312 evsignal_process(struct event_base *base)
 313 {
 314         struct evsignal_info *sig = &base->sig;
 315         struct event *ev, *next_ev;
 316         sig_atomic_t ncalls;
 317         int i;
 318
 319         base->sig.evsignal_caught = 0;
 320         for (i = 1; i < NSIG; ++i) {
 321                 ncalls = sig->evsigcaught[i];
 322                 if (ncalls == 0)
 323                         continue;
 324                 sig->evsigcaught[i] -= ncalls;
 325
 326                 for (ev = TAILQ_FIRST(&sig->evsigevents[i]);
 327                     ev != NULL; ev = next_ev) {
 328                         next_ev = TAILQ_NEXT(ev, ev_signal_next);
 329                         if (!(ev->ev_events & EV_PERSIST))
 330                                 event_del(ev);
 331                         event_active(ev, EV_SIGNAL, ncalls);
 332                 }
 333
 334         }
 335 }
 336
 337 void
 338 evsignal_dealloc(struct event_base *base)
 339 {
 340         int i = 0;
 341         if (base->sig.ev_signal_added) {
 342                 event_del(&base->sig.ev_signal);
 343                 base->sig.ev_signal_added = 0;
 344         }
 345         for (i = 0; i < NSIG; ++i) {
 346                 if (i < base->sig.sh_old_max && base->sig.sh_old[i] != NULL)
 347                         _evsignal_restore_handler(base, i);
 348         }
 349
 350         EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[0]);
 351         base->sig.ev_signal_pair[0] = -1;
 352         EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[1]);
 353         base->sig.ev_signal_pair[1] = -1;
 354         base->sig.sh_old_max = 0;
 355
 356         /* per index frees are handled in evsignal_del() */
 357         free(base->sig.sh_old);
 358 }