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_map_access,            /* map_access */
  68     no_lookup_name,           /* lookup_name */
  69     no_close_handle,          /* close_handle */
  70     handler_destroy           /* destroy */
  71 };
  72
  73 static void handler_poll_event( struct fd *fd, int event );
  74
  75 static const struct fd_ops handler_fd_ops =
  76 {
  77     NULL,                     /* get_poll_events */
  78     handler_poll_event,       /* poll_event */
  79     no_flush,                 /* flush */
  80     no_get_file_info,         /* get_file_info */
  81     no_queue_async,           /* queue_async */
  82     no_cancel_async           /* cancel_async */
  83 };
  84
  85 static struct handler *handler_sighup;
  86 static struct handler *handler_sigterm;
  87 static struct handler *handler_sigint;
  88 static struct handler *handler_sigchld;
  89 static struct handler *handler_sigio;
  90
  91 static sigset_t blocked_sigset;
  92
  93 static int watchdog;
  94
  95 /* create a signal handler */
  96 static struct handler *create_handler( signal_callback callback )
  97 {
  98     struct handler *handler;
  99     int fd[2];
 100
 101     if (pipe( fd ) == -1) return NULL;
 102     if (!(handler = alloc_object( &handler_ops )))
 103     {
 104         close( fd[0] );
 105         close( fd[1] );
 106         return NULL;
 107     }
 108     handler->pipe_write = fd[1];
 109     handler->pending    = 0;
 110     handler->callback   = callback;
 111
 112     if (!(handler->fd = create_anonymous_fd( &handler_fd_ops, fd[0], &handler->obj )))
 113     {
 114         release_object( handler );
 115         return NULL;
 116     }
 117     set_fd_events( handler->fd, POLLIN );
 118     return handler;
 119 }
 120
 121 /* handle a signal received for a given handler */
 122 static void do_signal( struct handler *handler )
 123 {
 124     if (!handler->pending)
 125     {
 126         char dummy = 0;
 127         handler->pending = 1;
 128         write( handler->pipe_write, &dummy, 1 );
 129     }
 130 }
 131
 132 static void handler_dump( struct object *obj, int verbose )
 133 {
 134     struct handler *handler = (struct handler *)obj;
 135     fprintf( stderr, "Signal handler fd=%p\n", handler->fd );
 136 }
 137
 138 static void handler_destroy( struct object *obj )
 139 {
 140     struct handler *handler = (struct handler *)obj;
 141     if (handler->fd) release_object( handler->fd );
 142     close( handler->pipe_write );
 143 }
 144
 145 static void handler_poll_event( struct fd *fd, int event )
 146 {
 147     struct handler *handler = get_fd_user( fd );
 148
 149     if (event & (POLLERR | POLLHUP))
 150     {
 151         /* this is not supposed to happen */
 152         fprintf( stderr, "wineserver: Error on signal handler pipe\n" );
 153         release_object( handler );
 154     }
 155     else if (event & POLLIN)
 156     {
 157         char dummy;
 158
 159         handler->pending = 0;
 160         read( get_unix_fd( handler->fd ), &dummy, 1 );
 161         handler->callback();
 162     }
 163 }
 164
 165 /* SIGHUP callback */
 166 static void sighup_callback(void)
 167 {
 168 #ifdef DEBUG_OBJECTS
 169     dump_objects();
 170 #endif
 171 }
 172
 173 /* SIGTERM callback */
 174 static void sigterm_callback(void)
 175 {
 176     flush_registry();
 177     exit(1);
 178 }
 179
 180 /* SIGINT callback */
 181 static void sigint_callback(void)
 182 {
 183     kill_all_processes( NULL, 1 );
 184     flush_registry();
 185     exit(1);
 186 }
 187
 188 /* SIGHUP handler */
 189 static void do_sighup( int signum )
 190 {
 191     do_signal( handler_sighup );
 192 }
 193
 194 /* SIGTERM handler */
 195 static void do_sigterm( int signum )
 196 {
 197     do_signal( handler_sigterm );
 198 }
 199
 200 /* SIGINT handler */
 201 static void do_sigint( int signum )
 202 {
 203     do_signal( handler_sigint );
 204 }
 205
 206 /* SIGALRM handler */
 207 static void do_sigalrm( int signum )
 208 {
 209     watchdog = 1;
 210 }
 211
 212 /* SIGCHLD handler */
 213 static void do_sigchld( int signum )
 214 {
 215     do_signal( handler_sigchld );
 216 }
 217
 218 /* SIGIO handler */
 219 #ifdef HAVE_SIGINFO_T_SI_FD
 220 static void do_sigio( int signum, siginfo_t *si, void *x )
 221 {
 222     do_signal( handler_sigio );
 223     do_change_notify( si->si_fd );
 224 }
 225 #endif
 226
 227 void start_watchdog(void)
 228 {
 229     alarm( 3 );
 230     watchdog = 0;
 231 }
 232
 233 void stop_watchdog(void)
 234 {
 235     alarm( 0 );
 236     watchdog = 0;
 237 }
 238
 239 int watchdog_triggered(void)
 240 {
 241     return watchdog != 0;
 242 }
 243
 244 void init_signals(void)
 245 {
 246     struct sigaction action;
 247
 248     if (!(handler_sighup  = create_handler( sighup_callback ))) goto error;
 249     if (!(handler_sigterm = create_handler( sigterm_callback ))) goto error;
 250     if (!(handler_sigint  = create_handler( sigint_callback ))) goto error;
 251     if (!(handler_sigchld = create_handler( sigchld_callback ))) goto error;
 252     if (!(handler_sigio   = create_handler( sigio_callback ))) goto error;
 253
 254     sigemptyset( &blocked_sigset );
 255     sigaddset( &blocked_sigset, SIGCHLD );
 256     sigaddset( &blocked_sigset, SIGHUP );
 257     sigaddset( &blocked_sigset, SIGINT );
 258     sigaddset( &blocked_sigset, SIGALRM );
 259     sigaddset( &blocked_sigset, SIGIO );
 260     sigaddset( &blocked_sigset, SIGQUIT );
 261     sigaddset( &blocked_sigset, SIGTERM );
 262 #ifdef SIG_PTHREAD_CANCEL
 263     sigaddset( &blocked_sigset, SIG_PTHREAD_CANCEL );
 264 #endif
 265
 266     action.sa_mask = blocked_sigset;
 267     action.sa_flags = 0;
 268     action.sa_handler = do_sigchld;
 269     sigaction( SIGCHLD, &action, NULL );
 270 #ifdef SIG_PTHREAD_CANCEL
 271     sigaction( SIG_PTHREAD_CANCEL, &action, NULL );
 272 #endif
 273     action.sa_handler = do_sighup;
 274     sigaction( SIGHUP, &action, NULL );
 275     action.sa_handler = do_sigint;
 276     sigaction( SIGINT, &action, NULL );
 277     action.sa_handler = do_sigalrm;
 278     sigaction( SIGALRM, &action, NULL );
 279     action.sa_handler = do_sigterm;
 280     sigaction( SIGQUIT, &action, NULL );
 281     sigaction( SIGTERM, &action, NULL );
 282     action.sa_handler = SIG_IGN;
 283     sigaction( SIGXFSZ, &action, NULL );
 284 #ifdef HAVE_SIGINFO_T_SI_FD
 285     action.sa_sigaction = do_sigio;
 286     action.sa_flags = SA_SIGINFO;
 287     sigaction( SIGIO, &action, NULL );
 288 #endif
 289     return;
 290
 291 error:
 292     fprintf( stderr, "failed to initialize signal handlers\n" );
 293     exit(1);
 294 }
 295
 296 void close_signals(void)
 297 {
 298     sigprocmask( SIG_BLOCK, &blocked_sigset, NULL );
 299     release_object( handler_sighup );
 300     release_object( handler_sigterm );
 301     release_object( handler_sigint );
 302     release_object( handler_sigchld );
 303     release_object( handler_sigio );
 304 }