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