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sig2.c
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sig2.c
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#include "apue.h"
static void sig_int(int);
int main(void)
{
sigset_t newmask,oldmask,waitmask;
pr_mask("program start:");
if(signal (SIGINT,sig_int) == SIG_ERR)
err_sys("signal(SIGINT) error");
sigemptyset(&waitmask);
sigaddset(&waitmask,SIGUSR1);
sigemptyset(&newmask);
sigaddset(&newmask,SIGINT);
/*
Block SIGINT and save current signal mask.
*
*/
if(sigprocmask(SIG_BLOCK,&newmask,&oldmask) < 0)
err_sys("SIG_BLOCK error");
/*
critical region of code.
*/
pr_mask("in critical region:");
/*
Pause, allowing all signals except SIGUSR1
*/
if(sigsuspend(&waitmask) != -1)
err_sys("sigsupsend error");
pr_mask("after return from sigsuspend:");
/*
* Reset signal mask which unblocks SIGINT.
*/
if(sigprocmask(SIG_SETMASK,&oldmask,NULL) < 0)
err_sys("SIG_SETMASK error");
/*
* And continue processing ...
*/
pr_mask("program exit:");
exit(0);
}
static void sig_int(int signo)
{
pr_mask("\n in sig_int:");
}