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_get_full_name,         /* get_full_name */
  77     no_lookup_name,           /* lookup_name */
  78     no_link_name,             /* link_name */
  79     NULL,                     /* unlink_name */
  80     no_open_file,             /* open_file */
  81     no_kernel_obj_list,       /* get_kernel_obj_list */
  82     no_close_handle,          /* close_handle */
  83     handler_destroy           /* destroy */
  84 };
  85
  86 static void handler_poll_event( struct fd *fd, int event );
  87
  88 static const struct fd_ops handler_fd_ops =
  89 {
  90     NULL,                     /* get_poll_events */
  91     handler_poll_event,       /* poll_event */
  92     NULL,                     /* flush */
  93     NULL,                     /* get_fd_type */
  94     NULL,                     /* ioctl */
  95     NULL,                     /* queue_async */
  96     NULL                      /* reselect_async */
  97 };
  98
  99 static struct handler *handler_sighup;
 100 static struct handler *handler_sigterm;
 101 static struct handler *handler_sigint;
 102 static struct handler *handler_sigchld;
 103 static struct handler *handler_sigio;
 104
 105 static int watchdog;
 106
 107 /* create a signal handler */
 108 static struct handler *create_handler( signal_callback callback )
 109 {
 110     struct handler *handler;
 111     int fd[2];
 112
 113     if (pipe( fd ) == -1) return NULL;
 114     if (!(handler = alloc_object( &handler_ops )))
 115     {
 116         close( fd[0] );
 117         close( fd[1] );
 118         return NULL;
 119     }
 120     handler->pipe_write = fd[1];
 121     handler->pending    = 0;
 122     handler->callback   = callback;
 123
 124     if (!(handler->fd = create_anonymous_fd( &handler_fd_ops, fd[0], &handler->obj, 0 )))
 125     {
 126         release_object( handler );
 127         return NULL;
 128     }
 129     set_fd_events( handler->fd, POLLIN );
 130     make_object_permanent( &handler->obj );
 131     return handler;
 132 }
 133
 134 /* handle a signal received for a given handler */
 135 static void do_signal( struct handler *handler )
 136 {
 137     if (!handler->pending)
 138     {
 139         char dummy = 0;
 140         handler->pending = 1;
 141         write( handler->pipe_write, &dummy, 1 );
 142     }
 143 }
 144
 145 static void handler_dump( struct object *obj, int verbose )
 146 {
 147     struct handler *handler = (struct handler *)obj;
 148     fprintf( stderr, "Signal handler fd=%p\n", handler->fd );
 149 }
 150
 151 static void handler_destroy( struct object *obj )
 152 {
 153     struct handler *handler = (struct handler *)obj;
 154     if (handler->fd) release_object( handler->fd );
 155     close( handler->pipe_write );
 156 }
 157
 158 static void handler_poll_event( struct fd *fd, int event )
 159 {
 160     struct handler *handler = get_fd_user( fd );
 161
 162     if (event & (POLLERR | POLLHUP))
 163     {
 164         /* this is not supposed to happen */
 165         fprintf( stderr, "wineserver: Error on signal handler pipe\n" );
 166         release_object( handler );
 167     }
 168     else if (event & POLLIN)
 169     {
 170         char dummy;
 171
 172         handler->pending = 0;
 173         read( get_unix_fd( handler->fd ), &dummy, 1 );
 174         handler->callback();
 175     }
 176 }
 177
 178 /* SIGHUP callback */
 179 static void sighup_callback(void)
 180 {
 181 #ifdef DEBUG_OBJECTS
 182     dump_objects();
 183 #endif
 184 }
 185
 186 /* SIGTERM callback */
 187 static void sigterm_callback(void)
 188 {
 189     flush_registry();
 190     exit(1);
 191 }
 192
 193 /* SIGINT callback */
 194 static void sigint_callback(void)
 195 {
 196     shutdown_master_socket();
 197 }
 198
 199 /* SIGHUP handler */
 200 static void do_sighup( int signum )
 201 {
 202     do_signal( handler_sighup );
 203 }
 204
 205 /* SIGTERM handler */
 206 static void do_sigterm( int signum )
 207 {
 208     do_signal( handler_sigterm );
 209 }
 210
 211 /* SIGINT handler */
 212 static void do_sigint( int signum )
 213 {
 214     do_signal( handler_sigint );
 215 }
 216
 217 /* SIGALRM handler */
 218 static void do_sigalrm( int signum )
 219 {
 220     watchdog = 1;
 221 }
 222
 223 /* SIGCHLD handler */
 224 static void do_sigchld( int signum )
 225 {
 226     do_signal( handler_sigchld );
 227 }
 228
 229 /* SIGSEGV handler */
 230 static void do_sigsegv( int signum )
 231 {
 232     fprintf( stderr, "wineserver crashed, please enable coredumps (ulimit -c unlimited) and restart.\n");
 233     abort();
 234 }
 235
 236 /* SIGIO handler */
 237 #ifdef HAVE_SIGINFO_T_SI_FD
 238 static void do_sigio( int signum, siginfo_t *si, void *x )
 239 {
 240     do_signal( handler_sigio );
 241     do_change_notify( si->si_fd );
 242 }
 243 #endif
 244
 245 void start_watchdog(void)
 246 {
 247     alarm( 3 );
 248     watchdog = 0;
 249 }
 250
 251 void stop_watchdog(void)
 252 {
 253     alarm( 0 );
 254     watchdog = 0;
 255 }
 256
 257 int watchdog_triggered(void)
 258 {
 259     return watchdog != 0;
 260 }
 261
 262 static int core_dump_disabled( void )
 263 {
 264     int r = 0;
 265 #ifdef RLIMIT_CORE
 266     struct rlimit lim;
 267
 268     r = !getrlimit(RLIMIT_CORE, &lim) && (lim.rlim_cur == 0);
 269 #endif
 270     return r;
 271 }
 272
 273 void init_signals(void)
 274 {
 275     struct sigaction action;
 276     sigset_t blocked_sigset;
 277
 278     if (!(handler_sighup  = create_handler( sighup_callback ))) goto error;
 279     if (!(handler_sigterm = create_handler( sigterm_callback ))) goto error;
 280     if (!(handler_sigint  = create_handler( sigint_callback ))) goto error;
 281     if (!(handler_sigchld = create_handler( sigchld_callback ))) goto error;
 282     if (!(handler_sigio   = create_handler( sigio_callback ))) goto error;
 283
 284     sigemptyset( &blocked_sigset );
 285     sigaddset( &blocked_sigset, SIGCHLD );
 286     sigaddset( &blocked_sigset, SIGHUP );
 287     sigaddset( &blocked_sigset, SIGINT );
 288     sigaddset( &blocked_sigset, SIGALRM );
 289     sigaddset( &blocked_sigset, SIGIO );
 290     sigaddset( &blocked_sigset, SIGQUIT );
 291     sigaddset( &blocked_sigset, SIGTERM );
 292 #ifdef SIG_PTHREAD_CANCEL
 293     sigaddset( &blocked_sigset, SIG_PTHREAD_CANCEL );
 294 #endif
 295
 296     action.sa_mask = blocked_sigset;
 297     action.sa_flags = 0;
 298     action.sa_handler = do_sigchld;
 299     sigaction( SIGCHLD, &action, NULL );
 300 #ifdef SIG_PTHREAD_CANCEL
 301     sigaction( SIG_PTHREAD_CANCEL, &action, NULL );
 302 #endif
 303     action.sa_handler = do_sighup;
 304     sigaction( SIGHUP, &action, NULL );
 305     action.sa_handler = do_sigint;
 306     sigaction( SIGINT, &action, NULL );
 307     action.sa_handler = do_sigalrm;
 308     sigaction( SIGALRM, &action, NULL );
 309     action.sa_handler = do_sigterm;
 310     sigaction( SIGQUIT, &action, NULL );
 311     sigaction( SIGTERM, &action, NULL );
 312     if (core_dump_disabled())
 313     {
 314         action.sa_handler = do_sigsegv;
 315         sigaction( SIGSEGV, &action, NULL );
 316     }
 317     action.sa_handler = SIG_IGN;
 318     sigaction( SIGXFSZ, &action, NULL );
 319 #ifdef HAVE_SIGINFO_T_SI_FD
 320     action.sa_sigaction = do_sigio;
 321     action.sa_flags = SA_SIGINFO;
 322     sigaction( SIGIO, &action, NULL );
 323 #endif
 324     return;
 325
 326 error:
 327     fprintf( stderr, "failed to initialize signal handlers\n" );
 328     exit(1);
 329 }