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