/* Code Example 4 */
#include <pthread.h>
#include <signal.h>
void* sig_handler( void* );
/* global variable used to indicate what signal
* (if any) has been caught
*/
int handled_signal = -1;
/* mutex to be used whenever accessing the above
* global data */
pthread_mutex_t sig_mutex = PTHREAD_MUTEX_INITIALIZER;
int main(void )
{
sigset_t signal_set;
pthread_t sig_thread;
/* block all signals */
sigfillset( &signal_set );
pthread_sigmask( SIG_BLOCK, &signal_set,
NULL );
/* create the signal handling thread */
pthread_create( &sig_thread, NULL,
sig_handler, NULL );
for (;;) {
/* whatever you want your program to
* do... */
/* grab the mutex before looking
* at handled_signal */
pthread_mutex_lock( &sig_mutex );
/* look to see if any signals have
* been caught */
switch ( handled_signal )
{
case -1:
/* no signal has been caught
* by the signal handler */
break;
case 0:
printf("The signal handler caught"
" a signal I'm not interested in "
"(%d)\n",
handled_signal );
handled_signal = -1;
break;
case SIGQUIT:
printf("The signal handler caught"
" a SIGQUIT signal!\n" );
handled_signal = -1;
break;
case SIGINT:
printf(
"The signal handler caught"
" a SIGINT signal!\n" );
handled_signal = -1;
break;
}
/* remember to release mutex */
pthread_mutex_unlock(&sig_mutex);
}
}
void* sig_handler( void* arg )
{
sigset_t signal_set;
int sig;
for(;;) {
/* wait for any and all signals */
sigfillset( &signal_set );
sigwait( &signal_set, &sig );
/* when we get this far, we've
* caught a signal */
switch( sig )
{
/* whatever you need to do on
* SIGQUIT */
case SIGQUIT:
pthread_mutex_lock(&sig_mutex);
handled_signal = SIGQUIT;
pthread_mutex_unlock(&sig_mutex);
break;
/* whatever you need to do on
* SIGINT */
case SIGINT:
pthread_mutex_lock(&sig_mutex);
handled_signal = SIGINT;
pthread_mutex_unlock(&sig_mutex);
break;
/* whatever you need to do for
* other signals */
default:
pthread_mutex_lock(&sig_mutex);
handled_signal = 0;
pthread_mutex_unlock(&sig_mutex);
break;
}
}
return (void*)0;
}
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