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_close_handle,          /* close_handle */
  68     handler_destroy           /* destroy */
  69 };
  70
  71 static void handler_poll_event( struct fd *fd, int event );
  72
  73 static const struct fd_ops handler_fd_ops =
  74 {
  75     NULL,                     /* get_poll_events */
  76     handler_poll_event,       /* poll_event */
  77     no_flush,                 /* flush */
  78     no_get_file_info,         /* get_file_info */
  79     no_queue_async,           /* queue_async */
  80     no_cancel_async           /* cancel_async */
  81 };
  82
  83 static struct handler *handler_sighup;
  84 static struct handler *handler_sigterm;
  85 static struct handler *handler_sigint;
  86 static struct handler *handler_sigchld;
  87 static struct handler *handler_sigio;
  88
  89 static sigset_t blocked_sigset;
  90
  91 static int watchdog;
  92
  93 /* create a signal handler */
  94 static struct handler *create_handler( signal_callback callback )
  95 {
  96     struct handler *handler;
  97     int fd[2];
  98
  99     if (pipe( fd ) == -1) return NULL;
 100     if (!(handler = alloc_object( &handler_ops )))
 101     {
 102         close( fd[0] );
 103         close( fd[1] );
 104         return NULL;
 105     }
 106     handler->pipe_write = fd[1];
 107     handler->pending    = 0;
 108     handler->callback   = callback;
 109
 110     if (!(handler->fd = create_anonymous_fd( &handler_fd_ops, fd[0], &handler->obj )))
 111     {
 112         release_object( handler );
 113         return NULL;
 114     }
 115     set_fd_events( handler->fd, POLLIN );
 116     return handler;
 117 }
 118
 119 /* handle a signal received for a given handler */
 120 static void do_signal( struct handler *handler )
 121 {
 122     if (!handler->pending)
 123     {
 124         char dummy = 0;
 125         handler->pending = 1;
 126         write( handler->pipe_write, &dummy, 1 );
 127     }
 128 }
 129
 130 static void handler_dump( struct object *obj, int verbose )
 131 {
 132     struct handler *handler = (struct handler *)obj;
 133     fprintf( stderr, "Signal handler fd=%p\n", handler->fd );
 134 }
 135
 136 static void handler_destroy( struct object *obj )
 137 {
 138     struct handler *handler = (struct handler *)obj;
 139     if (handler->fd) release_object( handler->fd );
 140     close( handler->pipe_write );
 141 }
 142
 143 static void handler_poll_event( struct fd *fd, int event )
 144 {
 145     struct handler *handler = get_fd_user( fd );
 146
 147     if (event & (POLLERR | POLLHUP))
 148     {
 149         /* this is not supposed to happen */
 150         fprintf( stderr, "wineserver: Error on signal handler pipe\n" );
 151         release_object( handler );
 152     }
 153     else if (event & POLLIN)
 154     {
 155         char dummy;
 156
 157         handler->pending = 0;
 158         read( get_unix_fd( handler->fd ), &dummy, 1 );
 159         handler->callback();
 160     }
 161 }
 162
 163 /* SIGHUP callback */
 164 static void sighup_callback(void)
 165 {
 166 #ifdef DEBUG_OBJECTS
 167     dump_objects();
 168 #endif
 169 }
 170
 171 /* SIGTERM callback */
 172 static void sigterm_callback(void)
 173 {
 174     flush_registry();
 175     exit(1);
 176 }
 177
 178 /* SIGINT callback */
 179 static void sigint_callback(void)
 180 {
 181     kill_all_processes( NULL, 1 );
 182     flush_registry();
 183     exit(1);
 184 }
 185
 186 /* SIGHUP handler */
 187 static void do_sighup( int signum )
 188 {
 189     do_signal( handler_sighup );
 190 }
 191
 192 /* SIGTERM handler */
 193 static void do_sigterm( int signum )
 194 {
 195     do_signal( handler_sigterm );
 196 }
 197
 198 /* SIGINT handler */
 199 static void do_sigint( int signum )
 200 {
 201     do_signal( handler_sigint );
 202 }
 203
 204 /* SIGALRM handler */
 205 static void do_sigalrm( int signum )
 206 {
 207     watchdog = 1;
 208 }
 209
 210 /* SIGCHLD handler */
 211 static void do_sigchld( int signum )
 212 {
 213     do_signal( handler_sigchld );
 214 }
 215
 216 /* SIGIO handler */
 217 #ifdef HAVE_SIGINFO_T_SI_FD
 218 static void do_sigio( int signum, siginfo_t *si, void *x )
 219 {
 220     do_signal( handler_sigio );
 221     do_change_notify( si->si_fd );
 222 }
 223 #endif
 224
 225 void start_watchdog(void)
 226 {
 227     alarm( 3 );
 228     watchdog = 0;
 229 }
 230
 231 void stop_watchdog(void)
 232 {
 233     alarm( 0 );
 234     watchdog = 0;
 235 }
 236
 237 int watchdog_triggered(void)
 238 {
 239     return watchdog != 0;
 240 }
 241
 242 void init_signals(void)
 243 {
 244     struct sigaction action;
 245
 246     if (!(handler_sighup  = create_handler( sighup_callback ))) goto error;
 247     if (!(handler_sigterm = create_handler( sigterm_callback ))) goto error;
 248     if (!(handler_sigint  = create_handler( sigint_callback ))) goto error;
 249     if (!(handler_sigchld = create_handler( sigchld_callback ))) goto error;
 250     if (!(handler_sigio   = create_handler( sigio_callback ))) goto error;
 251
 252     sigemptyset( &blocked_sigset );
 253     sigaddset( &blocked_sigset, SIGCHLD );
 254     sigaddset( &blocked_sigset, SIGHUP );
 255     sigaddset( &blocked_sigset, SIGINT );
 256     sigaddset( &blocked_sigset, SIGALRM );
 257     sigaddset( &blocked_sigset, SIGIO );
 258     sigaddset( &blocked_sigset, SIGQUIT );
 259     sigaddset( &blocked_sigset, SIGTERM );
 260 #ifdef SIG_PTHREAD_CANCEL
 261     sigaddset( &blocked_sigset, SIG_PTHREAD_CANCEL );
 262 #endif
 263
 264     action.sa_mask = blocked_sigset;
 265     action.sa_flags = 0;
 266     action.sa_handler = do_sigchld;
 267     sigaction( SIGCHLD, &action, NULL );
 268 #ifdef SIG_PTHREAD_CANCEL
 269     sigaction( SIG_PTHREAD_CANCEL, &action, NULL );
 270 #endif
 271     action.sa_handler = do_sighup;
 272     sigaction( SIGHUP, &action, NULL );
 273     action.sa_handler = do_sigint;
 274     sigaction( SIGINT, &action, NULL );
 275     action.sa_handler = do_sigalrm;
 276     sigaction( SIGALRM, &action, NULL );
 277     action.sa_handler = do_sigterm;
 278     sigaction( SIGQUIT, &action, NULL );
 279     sigaction( SIGTERM, &action, NULL );
 280     action.sa_handler = SIG_IGN;
 281     sigaction( SIGXFSZ, &action, NULL );
 282 #ifdef HAVE_SIGINFO_T_SI_FD
 283     action.sa_sigaction = do_sigio;
 284     action.sa_flags = SA_SIGINFO;
 285     sigaction( SIGIO, &action, NULL );
 286 #endif
 287     return;
 288
 289 error:
 290     fprintf( stderr, "failed to initialize signal handlers\n" );
 291     exit(1);
 292 }
 293
 294 void close_signals(void)
 295 {
 296     sigprocmask( SIG_BLOCK, &blocked_sigset, NULL );
 297     release_object( handler_sighup );
 298     release_object( handler_sigterm );
 299     release_object( handler_sigint );
 300     release_object( handler_sigchld );
 301     release_object( handler_sigio );
 302 }