third_party/libevent/signal.c

   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                 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
 203 int
 204 evsignal_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
 236 int
 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
 266 int
 267 evsignal_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
 286 static void
 287 evsignal_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
 310 void
 311 evsignal_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
 336 void
 337 evsignal_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 }