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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "config.h"
  22
  23 #include <signal.h>
  24 #include <stdio.h>
  25 #ifdef HAVE_POLL_H
  26 #include <poll.h>
  27 #endif
  28 #ifdef HAVE_SYS_POLL_H
  29 #include <sys/poll.h>
  30 #endif
  31 #include <unistd.h>
  32
  33 #include "file.h"
  34 #include "object.h"
  35 #include "process.h"
  36 #include "thread.h"
  37
  38 #if defined(linux) && defined(__SIGRTMIN)
  39 /* the signal used by linuxthreads as exit signal for clone() threads */
  40 # define SIG_PTHREAD_CANCEL (__SIGRTMIN+1)
  41 #endif
  42
  43 typedef void (*signal_callback)(void);
  44
  45 struct handler
  46 {
  47     struct object    obj;         /* object header */
  48     struct fd       *fd;          /* file descriptor for the pipe side */
  49     int              pipe_write;  /* unix fd for the pipe write side */
  50     volatile int     pending;     /* is signal pending? */
  51     signal_callback  callback;    /* callback function */
  52 };
  53
  54 static void handler_dump( struct object *obj, int verbose );
  55 static void handler_destroy( struct object *obj );
  56
  57 static const struct object_ops handler_ops =
  58 {
  59     sizeof(struct handler),   /* size */
  60     handler_dump,             /* dump */
  61     no_add_queue,             /* add_queue */
  62     NULL,                     /* remove_queue */
  63     NULL,                     /* signaled */
  64     NULL,                     /* satisfied */
  65     no_signal,                /* signal */
  66     no_get_fd,                /* get_fd */
  67     no_lookup_name,           /* lookup_name */
  68     no_close_handle,          /* close_handle */
  69     handler_destroy           /* destroy */
  70 };
  71
  72 static void handler_poll_event( struct fd *fd, int event );
  73
  74 static const struct fd_ops handler_fd_ops =
  75 {
  76     NULL,                     /* get_poll_events */
  77     handler_poll_event,       /* poll_event */
  78     no_flush,                 /* flush */
  79     no_get_file_info,         /* get_file_info */
  80     no_queue_async,           /* queue_async */
  81     no_cancel_async           /* cancel_async */
  82 };
  83
  84 static struct handler *handler_sighup;
  85 static struct handler *handler_sigterm;
  86 static struct handler *handler_sigint;
  87 static struct handler *handler_sigchld;
  88 static struct handler *handler_sigio;
  89
  90 static sigset_t blocked_sigset;
  91
  92 static int watchdog;
  93
  94 /* create a signal handler */
  95 static struct handler *create_handler( signal_callback callback )
  96 {
  97     struct handler *handler;
  98     int fd[2];
  99
 100     if (pipe( fd ) == -1) return NULL;
 101     if (!(handler = alloc_object( &handler_ops )))
 102     {
 103         close( fd[0] );
 104         close( fd[1] );
 105         return NULL;
 106     }
 107     handler->pipe_write = fd[1];
 108     handler->pending    = 0;
 109     handler->callback   = callback;
 110
 111     if (!(handler->fd = create_anonymous_fd( &handler_fd_ops, fd[0], &handler->obj )))
 112     {
 113         release_object( handler );
 114         return NULL;
 115     }
 116     set_fd_events( handler->fd, POLLIN );
 117     return handler;
 118 }
 119
 120 /* handle a signal received for a given handler */
 121 static void do_signal( struct handler *handler )
 122 {
 123     if (!handler->pending)
 124     {
 125         char dummy = 0;
 126         handler->pending = 1;
 127         write( handler->pipe_write, &dummy, 1 );
 128     }
 129 }
 130
 131 static void handler_dump( struct object *obj, int verbose )
 132 {
 133     struct handler *handler = (struct handler *)obj;
 134     fprintf( stderr, "Signal handler fd=%p\n", handler->fd );
 135 }
 136
 137 static void handler_destroy( struct object *obj )
 138 {
 139     struct handler *handler = (struct handler *)obj;
 140     if (handler->fd) release_object( handler->fd );
 141     close( handler->pipe_write );
 142 }
 143
 144 static void handler_poll_event( struct fd *fd, int event )
 145 {
 146     struct handler *handler = get_fd_user( fd );
 147
 148     if (event & (POLLERR | POLLHUP))
 149     {
 150         /* this is not supposed to happen */
 151         fprintf( stderr, "wineserver: Error on signal handler pipe\n" );
 152         release_object( handler );
 153     }
 154     else if (event & POLLIN)
 155     {
 156         char dummy;
 157
 158         handler->pending = 0;
 159         read( get_unix_fd( handler->fd ), &dummy, 1 );
 160         handler->callback();
 161     }
 162 }
 163
 164 /* SIGHUP callback */
 165 static void sighup_callback(void)
 166 {
 167 #ifdef DEBUG_OBJECTS
 168     dump_objects();
 169 #endif
 170 }
 171
 172 /* SIGTERM callback */
 173 static void sigterm_callback(void)
 174 {
 175     flush_registry();
 176     exit(1);
 177 }
 178
 179 /* SIGINT callback */
 180 static void sigint_callback(void)
 181 {
 182     kill_all_processes( NULL, 1 );
 183     flush_registry();
 184     exit(1);
 185 }
 186
 187 /* SIGHUP handler */
 188 static void do_sighup( int signum )
 189 {
 190     do_signal( handler_sighup );
 191 }
 192
 193 /* SIGTERM handler */
 194 static void do_sigterm( int signum )
 195 {
 196     do_signal( handler_sigterm );
 197 }
 198
 199 /* SIGINT handler */
 200 static void do_sigint( int signum )
 201 {
 202     do_signal( handler_sigint );
 203 }
 204
 205 /* SIGALRM handler */
 206 static void do_sigalrm( int signum )
 207 {
 208     watchdog = 1;
 209 }
 210
 211 /* SIGCHLD handler */
 212 static void do_sigchld( int signum )
 213 {
 214     do_signal( handler_sigchld );
 215 }
 216
 217 /* SIGIO handler */
 218 #ifdef HAVE_SIGINFO_T_SI_FD
 219 static void do_sigio( int signum, siginfo_t *si, void *x )
 220 {
 221     do_signal( handler_sigio );
 222     do_change_notify( si->si_fd );
 223 }
 224 #endif
 225
 226 void start_watchdog(void)
 227 {
 228     alarm( 3 );
 229     watchdog = 0;
 230 }
 231
 232 void stop_watchdog(void)
 233 {
 234     alarm( 0 );
 235     watchdog = 0;
 236 }
 237
 238 int watchdog_triggered(void)
 239 {
 240     return watchdog != 0;
 241 }
 242
 243 void init_signals(void)
 244 {
 245     struct sigaction action;
 246
 247     if (!(handler_sighup  = create_handler( sighup_callback ))) goto error;
 248     if (!(handler_sigterm = create_handler( sigterm_callback ))) goto error;
 249     if (!(handler_sigint  = create_handler( sigint_callback ))) goto error;
 250     if (!(handler_sigchld = create_handler( sigchld_callback ))) goto error;
 251     if (!(handler_sigio   = create_handler( sigio_callback ))) goto error;
 252
 253     sigemptyset( &blocked_sigset );
 254     sigaddset( &blocked_sigset, SIGCHLD );
 255     sigaddset( &blocked_sigset, SIGHUP );
 256     sigaddset( &blocked_sigset, SIGINT );
 257     sigaddset( &blocked_sigset, SIGALRM );
 258     sigaddset( &blocked_sigset, SIGIO );
 259     sigaddset( &blocked_sigset, SIGQUIT );
 260     sigaddset( &blocked_sigset, SIGTERM );
 261 #ifdef SIG_PTHREAD_CANCEL
 262     sigaddset( &blocked_sigset, SIG_PTHREAD_CANCEL );
 263 #endif
 264
 265     action.sa_mask = blocked_sigset;
 266     action.sa_flags = 0;
 267     action.sa_handler = do_sigchld;
 268     sigaction( SIGCHLD, &action, NULL );
 269 #ifdef SIG_PTHREAD_CANCEL
 270     sigaction( SIG_PTHREAD_CANCEL, &action, NULL );
 271 #endif
 272     action.sa_handler = do_sighup;
 273     sigaction( SIGHUP, &action, NULL );
 274     action.sa_handler = do_sigint;
 275     sigaction( SIGINT, &action, NULL );
 276     action.sa_handler = do_sigalrm;
 277     sigaction( SIGALRM, &action, NULL );
 278     action.sa_handler = do_sigterm;
 279     sigaction( SIGQUIT, &action, NULL );
 280     sigaction( SIGTERM, &action, NULL );
 281     action.sa_handler = SIG_IGN;
 282     sigaction( SIGXFSZ, &action, NULL );
 283 #ifdef HAVE_SIGINFO_T_SI_FD
 284     action.sa_sigaction = do_sigio;
 285     action.sa_flags = SA_SIGINFO;
 286     sigaction( SIGIO, &action, NULL );
 287 #endif
 288     return;
 289
 290 error:
 291     fprintf( stderr, "failed to initialize signal handlers\n" );
 292     exit(1);
 293 }
 294
 295 void close_signals(void)
 296 {
 297     sigprocmask( SIG_BLOCK, &blocked_sigset, NULL );
 298     release_object( handler_sighup );
 299     release_object( handler_sigterm );
 300     release_object( handler_sigint );
 301     release_object( handler_sigchld );
 302     release_object( handler_sigio );
 303 }