[unix]SIGQUIT信号堵塞的测试

#include <apue.h>
#include <errno.h>

static void sig_quit(int);
int main(void)
{
sigset_t newmask, oldmask, pendmask;
if(signal(SIGQUIT,sig_quit) == SIG_ERR)
err_sys("can't catch SIGQUIT");
/**
* Block SIGQUIT and save current signal mask
*/

sigemptyset(&newmask);
sigaddset(&newmask,SIGQUIT);
if(sigprocmask(SIG_BLOCK,&newmask,&oldmask) < 0)
err_sys("SIG_BLOCK error!");
sleep(5);  /* SIGQUIT here will remain pending */
if(sigpending(&pendmask) < 0)
err_sys("sigpending error");
if(sigismember(&pendmask,SIGQUIT))
printf("\nSIGQUIT pending\n");
/**
* Restore signal mask which unblocks SIGQUIT.
*/
if(sigprocmask(SIG_SETMASK,&oldmask,NULL) < 0)
err_sys("SIG_SETMASK error");
printf("SIGQUIT unblocked\n");
sleep(5); /* SIGQUIT here will terminate with core file. */
exit(0);
}

static void sig_quit(int signo)
{
printf("caught SIGQUIT\n");
if(signal(SIGQUIT,SIG_DFL) == SIG_ERR)
err_sys("can't reset SIGQUIT");
}