restart main via longjmp atexit

#include <setjmp.h>  // setjmp/longjmp
#include <unistd.h>  // sleep
#include <stdio.h>   // printf
#include <stdlib.h>  // exit, atexit

jmp_buf panic_restart;
int panic_restart_count=0;

void
do_the_panic_restart()
{
    if (panic_restart_count++ < 3)
        longjmp(panic_restart, 1);
}

int
main(int argc, char **argv)
{
    if(setjmp(panic_restart)) {
        fprintf(stderr,"PANIC! main() has been restarted due to a unscheduled exit!\n");
    }
    atexit(&do_the_panic_restart);

    printf("This is main. I will sleep a while, then try to exit.\n");
    sleep(1);
    exit(1);
}