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#include "apue.h"
#include <setjmp.h>
#include <time.h>
static void sig_usr1(int);
static void sig_alrm(int);
static sigjmp_buf jmpbuf;
static volatile sig_atomic_t canjump;
int
main(void)
{
if (signal(SIGUSR1, sig_usr1) == SIG_ERR)
err_sys("signal(SIGUSR1) error");
if (signal(SIGALRM, sig_alrm) == SIG_ERR)
err_sys("signal(SIGALRM) error");
pr_mask("starting main: "); /* {Prog prmask} */
if (sigsetjmp(jmpbuf, 1)) {
pr_mask("ending main: ");
exit(0);
}
canjump = 1; /* now sigsetjmp() is OK */
for ( ; ; )
pause();
}
static void
sig_usr1(int signo)
{
time_t starttime;
if (canjump == 0)
return; /* unexpected signal, ignore */
pr_mask("starting sig_usr1: ");
alarm(3); /* SIGALRM in 3 seconds */
starttime = time(NULL);
for ( ; ; ) /* busy wait for 5 seconds */
if (time(NULL) > starttime + 5)
break;
pr_mask("finishing sig_usr1: ");
canjump = 0;
siglongjmp(jmpbuf, 1); /* jump back to main, don't return */
}
static void
sig_alrm(int signo)
{
pr_mask("in sig_alrm: ");
}
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