server/signal.c

   1 /*
   2  * Server signal handling
   3  *
   4  * Copyright (C) 2003 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  */
  20
  21 #include "config.h"
  22
  23 #include <signal.h>
  24 #include <stdio.h>
  25 #include <sys/time.h>
  26 #ifdef HAVE_POLL_H
  27 #include <poll.h>
  28 #endif
  29 #ifdef HAVE_SYS_POLL_H
  30 #include <sys/poll.h>
  31 #endif
  32 #ifdef HAVE_SYS_RESOURCE_H
  33 #include <sys/resource.h>
  34 #endif
  35 #include <unistd.h>
  36
  37 #include "file.h"
  38 #include "object.h"
  39 #include "process.h"
  40 #include "thread.h"
  41 #include "request.h"
  42
  43 #if defined(linux) && defined(__SIGRTMIN)
  44 /* the signal used by linuxthreads as exit signal for clone() threads */
  45 # define SIG_PTHREAD_CANCEL (__SIGRTMIN+1)
  46 #endif
  47
  48 typedef void (*signal_callback)(void);
  49
  50 struct handler
  51 {
  52     struct object    obj;         /* object header */
  53     struct fd       *fd;          /* file descriptor for the pipe side */
  54     int              pipe_write;  /* unix fd for the pipe write side */
  55     volatile int     pending;     /* is signal pending? */
  56     signal_callback  callback;    /* callback function */
  57 };
  58
  59 static void handler_dump( struct object *obj, int verbose );
  60 static void handler_destroy( struct object *obj );
  61
  62 static const struct object_ops handler_ops =
  63 {
  64     sizeof(struct handler),   /* size */
  65     handler_dump,             /* dump */
  66     no_get_type,              /* get_type */
  67     no_add_queue,             /* add_queue */
  68     NULL,                     /* remove_queue */
  69     NULL,                     /* signaled */
  70     NULL,                     /* satisfied */
  71     no_signal,                /* signal */
  72     no_get_fd,                /* get_fd */
  73     no_map_access,            /* map_access */
  74     default_get_sd,           /* get_sd */
  75     default_set_sd,           /* set_sd */
  76     no_lookup_name,           /* lookup_name */
  77     no_open_file,             /* open_file */
  78     no_close_handle,          /* close_handle */
  79     handler_destroy           /* destroy */
  80 };
  81
  82 static void handler_poll_event( struct fd *fd, int event );
  83
  84 static const struct fd_ops handler_fd_ops =
  85 {
  86     NULL,                     /* get_poll_events */
  87     handler_poll_event,       /* poll_event */
  88     NULL,                     /* flush */
  89     NULL,                     /* get_fd_type */
  90     NULL,                     /* ioctl */
  91     NULL,                     /* queue_async */
  92     NULL,                     /* reselect_async */
  93     NULL                      /* cancel_async */
  94 };
  95
  96 static struct handler *handler_sighup;
  97 static struct handler *handler_sigterm;
  98 static struct handler *handler_sigint;
  99 static struct handler *handler_sigchld;
 100 static struct handler *handler_sigio;
 101
 102 static int watchdog;
 103
 104 /* create a signal handler */
 105 static struct handler *create_handler( signal_callback callback )
 106 {
 107     struct handler *handler;
 108     int fd[2];
 109
 110     if (pipe( fd ) == -1) return NULL;
 111     if (!(handler = alloc_object( &handler_ops )))
 112     {
 113         close( fd[0] );
 114         close( fd[1] );
 115         return NULL;
 116     }
 117     handler->pipe_write = fd[1];
 118     handler->pending    = 0;
 119     handler->callback   = callback;
 120
 121     if (!(handler->fd = create_anonymous_fd( &handler_fd_ops, fd[0], &handler->obj, 0 )))
 122     {
 123         release_object( handler );
 124         return NULL;
 125     }
 126     set_fd_events( handler->fd, POLLIN );
 127     make_object_static( &handler->obj );
 128     return handler;
 129 }
 130
 131 /* handle a signal received for a given handler */
 132 static void do_signal( struct handler *handler )
 133 {
 134     if (!handler->pending)
 135     {
 136         char dummy = 0;
 137         handler->pending = 1;
 138         write( handler->pipe_write, &dummy, 1 );
 139     }
 140 }
 141
 142 static void handler_dump( struct object *obj, int verbose )
 143 {
 144     struct handler *handler = (struct handler *)obj;
 145     fprintf( stderr, "Signal handler fd=%p\n", handler->fd );
 146 }
 147
 148 static void handler_destroy( struct object *obj )
 149 {
 150     struct handler *handler = (struct handler *)obj;
 151     if (handler->fd) release_object( handler->fd );
 152     close( handler->pipe_write );
 153 }
 154
 155 static void handler_poll_event( struct fd *fd, int event )
 156 {
 157     struct handler *handler = get_fd_user( fd );
 158
 159     if (event & (POLLERR | POLLHUP))
 160     {
 161         /* this is not supposed to happen */
 162         fprintf( stderr, "wineserver: Error on signal handler pipe\n" );
 163         release_object( handler );
 164     }
 165     else if (event & POLLIN)
 166     {
 167         char dummy;
 168
 169         handler->pending = 0;
 170         read( get_unix_fd( handler->fd ), &dummy, 1 );
 171         handler->callback();
 172     }
 173 }
 174
 175 /* SIGHUP callback */
 176 static void sighup_callback(void)
 177 {
 178 #ifdef DEBUG_OBJECTS
 179     dump_objects();
 180 #endif
 181 }
 182
 183 /* SIGTERM callback */
 184 static void sigterm_callback(void)
 185 {
 186     flush_registry();
 187     exit(1);
 188 }
 189
 190 /* SIGINT callback */
 191 static void sigint_callback(void)
 192 {
 193     shutdown_master_socket();
 194 }
 195
 196 /* SIGHUP handler */
 197 static void do_sighup( int signum )
 198 {
 199     do_signal( handler_sighup );
 200 }
 201
 202 /* SIGTERM handler */
 203 static void do_sigterm( int signum )
 204 {
 205     do_signal( handler_sigterm );
 206 }
 207
 208 /* SIGINT handler */
 209 static void do_sigint( int signum )
 210 {
 211     do_signal( handler_sigint );
 212 }
 213
 214 /* SIGALRM handler */
 215 static void do_sigalrm( int signum )
 216 {
 217     watchdog = 1;
 218 }
 219
 220 /* SIGCHLD handler */
 221 static void do_sigchld( int signum )
 222 {
 223     do_signal( handler_sigchld );
 224 }
 225
 226 /* SIGSEGV handler */
 227 static void do_sigsegv( int signum )
 228 {
 229     fprintf( stderr, "wineserver crashed, please enable coredumps (ulimit -c unlimited) and restart.\n");
 230     abort();
 231 }
 232
 233 /* SIGIO handler */
 234 #ifdef HAVE_SIGINFO_T_SI_FD
 235 static void do_sigio( int signum, siginfo_t *si, void *x )
 236 {
 237     do_signal( handler_sigio );
 238     do_change_notify( si->si_fd );
 239 }
 240 #endif
 241
 242 void start_watchdog(void)
 243 {
 244     alarm( 3 );
 245     watchdog = 0;
 246 }
 247
 248 void stop_watchdog(void)
 249 {
 250     alarm( 0 );
 251     watchdog = 0;
 252 }
 253
 254 int watchdog_triggered(void)
 255 {
 256     return watchdog != 0;
 257 }
 258
 259 static int core_dump_disabled( void )
 260 {
 261     int r = 0;
 262 #ifdef RLIMIT_CORE
 263     struct rlimit lim;
 264
 265     r = !getrlimit(RLIMIT_CORE, &lim) && (lim.rlim_cur == 0);
 266 #endif
 267     return r;
 268 }
 269
 270 void init_signals(void)
 271 {
 272     struct sigaction action;
 273     sigset_t blocked_sigset;
 274
 275     if (!(handler_sighup  = create_handler( sighup_callback ))) goto error;
 276     if (!(handler_sigterm = create_handler( sigterm_callback ))) goto error;
 277     if (!(handler_sigint  = create_handler( sigint_callback ))) goto error;
 278     if (!(handler_sigchld = create_handler( sigchld_callback ))) goto error;
 279     if (!(handler_sigio   = create_handler( sigio_callback ))) goto error;
 280
 281     sigemptyset( &blocked_sigset );
 282     sigaddset( &blocked_sigset, SIGCHLD );
 283     sigaddset( &blocked_sigset, SIGHUP );
 284     sigaddset( &blocked_sigset, SIGINT );
 285     sigaddset( &blocked_sigset, SIGALRM );
 286     sigaddset( &blocked_sigset, SIGIO );
 287     sigaddset( &blocked_sigset, SIGQUIT );
 288     sigaddset( &blocked_sigset, SIGTERM );
 289 #ifdef SIG_PTHREAD_CANCEL
 290     sigaddset( &blocked_sigset, SIG_PTHREAD_CANCEL );
 291 #endif
 292
 293     action.sa_mask = blocked_sigset;
 294     action.sa_flags = 0;
 295     action.sa_handler = do_sigchld;
 296     sigaction( SIGCHLD, &action, NULL );
 297 #ifdef SIG_PTHREAD_CANCEL
 298     sigaction( SIG_PTHREAD_CANCEL, &action, NULL );
 299 #endif
 300     action.sa_handler = do_sighup;
 301     sigaction( SIGHUP, &action, NULL );
 302     action.sa_handler = do_sigint;
 303     sigaction( SIGINT, &action, NULL );
 304     action.sa_handler = do_sigalrm;
 305     sigaction( SIGALRM, &action, NULL );
 306     action.sa_handler = do_sigterm;
 307     sigaction( SIGQUIT, &action, NULL );
 308     sigaction( SIGTERM, &action, NULL );
 309     if (core_dump_disabled())
 310     {
 311         action.sa_handler = do_sigsegv;
 312         sigaction( SIGSEGV, &action, NULL );
 313     }
 314     action.sa_handler = SIG_IGN;
 315     sigaction( SIGXFSZ, &action, NULL );
 316 #ifdef HAVE_SIGINFO_T_SI_FD
 317     action.sa_sigaction = do_sigio;
 318     action.sa_flags = SA_SIGINFO;
 319     sigaction( SIGIO, &action, NULL );
 320 #endif
 321     return;
 322
 323 error:
 324     fprintf( stderr, "failed to initialize signal handlers\n" );
 325     exit(1);
 326 }