/*      $OpenBSD: sig-stop.c,v 1.2 2024/08/23 12:56:26 anton Exp $      */
/*
 *      Written by Artur Grabowski <art@openbsd.org> 2007 Public Domain.
 */
#include <sys/types.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <time.h>
#include <err.h>
#include <signal.h>

int
main(int argc, char **argv)
{
        struct timespec ts;
        pid_t child;
        int status;
        int count;
        int toggle = 0;

        switch((child = fork())) {
        case -1:
                err(1, "fork");
        case 0:
                ts.tv_sec = 0;
                ts.tv_nsec = 1000;
                for (count = 0; count < 100; count++) {
                        nanosleep(&ts, NULL);
                }
                exit(0);
        default:
                break;
        }

        ts.tv_sec = 1;
        ts.tv_nsec = 0;
        nanosleep(&ts, NULL);

        do {
                toggle ^= 1;
                if (kill(child, toggle ? SIGSTOP : SIGCONT)) {
                        if (wait(&status) < 0)
                                err(1, "wait");
                        break;
                }
        } while(waitpid(child, &status, WCONTINUED|WUNTRACED) > 0 &&
            (toggle ? WIFSTOPPED(status) : WIFCONTINUED(status)));

        if (!WIFEXITED(status))
                err(1, "bad status: %d", status);

        return 0;
}