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#include <signal.h>
#include <setjmp.h>
/*
* The environment for setjmp.
*/
jmp_buf env;
main()
{
int i;
char buf[16];
extern int timeout();
/*
* Inform the system we want to catch the
* alarm signal.
*/
signal(SIGALRM, timeout);
/*
* The code inside the if gets executed the first
* time through setjmp, the code inside the else
* the second time.
*/
if (setjmp(env) == 0) {
/*
* Issue a request for an alarm to be
* delivered in 15 seconds.
*/
alarm(15);
/*
* Prompt for input.
*/
printf("Type a word; if you don't in 15 ");
printf("seconds I'll use \"WORD\": ");
gets(buf);
/*
* Turn off the alarm.
*/
alarm(0);
}
else {
/*
* Assume the default.
*/
strcpy(buf, "WORD");
}
printf("\nThe word is: %s\n", buf);
exit(0);
}
/*
* timeout--catch the signal.
*/
timeout(sig)
int sig;
{
/*
* Ignore the signal for the duration of this
* routine.
*/
signal(sig, SIG_IGN);
/*
* We would perform any timeout-related
* functions here; in this case there
* are none.
*/
/*
* Restore the action of the alarm signal.
*/
signal(SIGALRM, timeout);
/*
* Return to the main routine at setjmp,
* and make setjmp return 1.
*/
longjmp(env, 1);
}
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