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 #include <poll.h>
  27 #ifdef HAVE_SYS_RESOURCE_H
  28 #include <sys/resource.h>
  29 #endif
  30 #include <unistd.h>
  31
  32 #include "file.h"
  33 #include "object.h"
  34 #include "process.h"
  35 #include "thread.h"
  36 #include "request.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     &no_type,                 /* type */
  61     handler_dump,             /* dump */
  62     no_add_queue,             /* add_queue */
  63     NULL,                     /* remove_queue */
  64     NULL,                     /* signaled */
  65     NULL,                     /* satisfied */
  66     no_signal,                /* signal */
  67     no_get_fd,                /* get_fd */
  68     default_map_access,       /* map_access */
  69     default_get_sd,           /* get_sd */
  70     default_set_sd,           /* set_sd */
  71     no_get_full_name,         /* get_full_name */
  72     no_lookup_name,           /* lookup_name */
  73     no_link_name,             /* link_name */
  74     NULL,                     /* unlink_name */
  75     no_open_file,             /* open_file */
  76     no_kernel_obj_list,       /* get_kernel_obj_list */
  77     no_close_handle,          /* close_handle */
  78     handler_destroy           /* destroy */
  79 };
  80
  81 static void handler_poll_event( struct fd *fd, int event );
  82
  83 static const struct fd_ops handler_fd_ops =
  84 {
  85     NULL,                     /* get_poll_events */
  86     handler_poll_event,       /* poll_event */
  87     NULL,                     /* flush */
  88     NULL,                     /* get_fd_type */
  89     NULL,                     /* ioctl */
  90     NULL,                     /* queue_async */
  91     NULL                      /* reselect_async */
  92 };
  93
  94 static struct handler *handler_sighup;
  95 static struct handler *handler_sigterm;
  96 static struct handler *handler_sigint;
  97 static struct handler *handler_sigchld;
  98 static struct handler *handler_sigio;
  99
 100 static int watchdog;
 101
 102 /* create a signal handler */
 103 static struct handler *create_handler( signal_callback callback )
 104 {
 105     struct handler *handler;
 106     int fd[2];
 107
 108     if (pipe( fd ) == -1) return NULL;
 109     if (!(handler = alloc_object( &handler_ops )))
 110     {
 111         close( fd[0] );
 112         close( fd[1] );
 113         return NULL;
 114     }
 115     handler->pipe_write = fd[1];
 116     handler->pending    = 0;
 117     handler->callback   = callback;
 118
 119     if (!(handler->fd = create_anonymous_fd( &handler_fd_ops, fd[0], &handler->obj, 0 )))
 120     {
 121         release_object( handler );
 122         return NULL;
 123     }
 124     set_fd_events( handler->fd, POLLIN );
 125     make_object_permanent( &handler->obj );
 126     return handler;
 127 }
 128
 129 /* handle a signal received for a given handler */
 130 static void do_signal( struct handler *handler )
 131 {
 132     if (!handler->pending)
 133     {
 134         char dummy = 0;
 135         handler->pending = 1;
 136         write( handler->pipe_write, &dummy, 1 );
 137     }
 138 }
 139
 140 static void handler_dump( struct object *obj, int verbose )
 141 {
 142     struct handler *handler = (struct handler *)obj;
 143     fprintf( stderr, "Signal handler fd=%p\n", handler->fd );
 144 }
 145
 146 static void handler_destroy( struct object *obj )
 147 {
 148     struct handler *handler = (struct handler *)obj;
 149     if (handler->fd) release_object( handler->fd );
 150     close( handler->pipe_write );
 151 }
 152
 153 static void handler_poll_event( struct fd *fd, int event )
 154 {
 155     struct handler *handler = get_fd_user( fd );
 156
 157     if (event & (POLLERR | POLLHUP))
 158     {
 159         /* this is not supposed to happen */
 160         fprintf( stderr, "wineserver: Error on signal handler pipe\n" );
 161         release_object( handler );
 162     }
 163     else if (event & POLLIN)
 164     {
 165         char dummy;
 166
 167         handler->pending = 0;
 168         read( get_unix_fd( handler->fd ), &dummy, 1 );
 169         handler->callback();
 170     }
 171 }
 172
 173 /* SIGHUP callback */
 174 static void sighup_callback(void)
 175 {
 176 #ifdef DEBUG_OBJECTS
 177     dump_objects();
 178 #endif
 179 }
 180
 181 /* SIGTERM callback */
 182 static void sigterm_callback(void)
 183 {
 184     flush_registry();
 185     exit(1);
 186 }
 187
 188 /* SIGINT callback */
 189 static void sigint_callback(void)
 190 {
 191     shutdown_master_socket();
 192 }
 193
 194 /* SIGHUP handler */
 195 static void do_sighup( int signum )
 196 {
 197     do_signal( handler_sighup );
 198 }
 199
 200 /* SIGTERM handler */
 201 static void do_sigterm( int signum )
 202 {
 203     do_signal( handler_sigterm );
 204 }
 205
 206 /* SIGINT handler */
 207 static void do_sigint( int signum )
 208 {
 209     do_signal( handler_sigint );
 210 }
 211
 212 /* SIGALRM handler */
 213 static void do_sigalrm( int signum )
 214 {
 215     watchdog = 1;
 216 }
 217
 218 /* SIGCHLD handler */
 219 static void do_sigchld( int signum )
 220 {
 221     do_signal( handler_sigchld );
 222 }
 223
 224 /* SIGSEGV handler */
 225 static void do_sigsegv( int signum )
 226 {
 227     fprintf( stderr, "wineserver crashed, please enable coredumps (ulimit -c unlimited) and restart.\n");
 228     abort();
 229 }
 230
 231 /* SIGIO handler */
 232 #ifdef HAVE_SIGINFO_T_SI_FD
 233 static void do_sigio( int signum, siginfo_t *si, void *x )
 234 {
 235     do_signal( handler_sigio );
 236     do_change_notify( si->si_fd );
 237 }
 238 #endif
 239
 240 void start_watchdog(void)
 241 {
 242     alarm( 3 );
 243     watchdog = 0;
 244 }
 245
 246 void stop_watchdog(void)
 247 {
 248     alarm( 0 );
 249     watchdog = 0;
 250 }
 251
 252 int watchdog_triggered(void)
 253 {
 254     return watchdog != 0;
 255 }
 256
 257 static int core_dump_disabled( void )
 258 {
 259     int r = 0;
 260 #ifdef RLIMIT_CORE
 261     struct rlimit lim;
 262
 263     r = !getrlimit(RLIMIT_CORE, &lim) && (lim.rlim_cur == 0);
 264 #endif
 265     return r;
 266 }
 267
 268 void init_signals(void)
 269 {
 270     struct sigaction action;
 271     sigset_t blocked_sigset;
 272
 273     if (!(handler_sighup  = create_handler( sighup_callback ))) goto error;
 274     if (!(handler_sigterm = create_handler( sigterm_callback ))) goto error;
 275     if (!(handler_sigint  = create_handler( sigint_callback ))) goto error;
 276     if (!(handler_sigchld = create_handler( sigchld_callback ))) goto error;
 277     if (!(handler_sigio   = create_handler( sigio_callback ))) goto error;
 278
 279     sigemptyset( &blocked_sigset );
 280     sigaddset( &blocked_sigset, SIGCHLD );
 281     sigaddset( &blocked_sigset, SIGHUP );
 282     sigaddset( &blocked_sigset, SIGINT );
 283     sigaddset( &blocked_sigset, SIGALRM );
 284     sigaddset( &blocked_sigset, SIGIO );
 285     sigaddset( &blocked_sigset, SIGQUIT );
 286     sigaddset( &blocked_sigset, SIGTERM );
 287 #ifdef SIG_PTHREAD_CANCEL
 288     sigaddset( &blocked_sigset, SIG_PTHREAD_CANCEL );
 289 #endif
 290
 291     action.sa_mask = blocked_sigset;
 292     action.sa_flags = 0;
 293     action.sa_handler = do_sigchld;
 294     sigaction( SIGCHLD, &action, NULL );
 295 #ifdef SIG_PTHREAD_CANCEL
 296     sigaction( SIG_PTHREAD_CANCEL, &action, NULL );
 297 #endif
 298     action.sa_handler = do_sighup;
 299     sigaction( SIGHUP, &action, NULL );
 300     action.sa_handler = do_sigint;
 301     sigaction( SIGINT, &action, NULL );
 302     action.sa_handler = do_sigalrm;
 303     sigaction( SIGALRM, &action, NULL );
 304     action.sa_handler = do_sigterm;
 305     sigaction( SIGQUIT, &action, NULL );
 306     sigaction( SIGTERM, &action, NULL );
 307     if (core_dump_disabled())
 308     {
 309         action.sa_handler = do_sigsegv;
 310         sigaction( SIGSEGV, &action, NULL );
 311     }
 312     action.sa_handler = SIG_IGN;
 313     sigaction( SIGXFSZ, &action, NULL );
 314 #ifdef HAVE_SIGINFO_T_SI_FD
 315     action.sa_sigaction = do_sigio;
 316     action.sa_flags = SA_SIGINFO;
 317     sigaction( SIGIO, &action, NULL );
 318 #endif
 319     return;
 320
 321 error:
 322     fprintf( stderr, "failed to initialize signal handlers\n" );
 323     exit(1);
 324 }