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