/*
 * Copyright 2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
 * Distributed under the terms of the MIT License.
 */


#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>


/*!
        waitpid() should wait only once.
*/


int
child2()
{
        printf("child 2 1. parent id = %ld\n", getppid());
        sleep(2);
        printf("child 2 2. parent id = %ld\n", getppid());
        return 2;
}


//! exits before child 2
int
child1()
{
        printf("child 1 process group: %ld\n", getpgrp());

        pid_t child = fork();
        if (child == 0)
                return child2();

        sleep(1);
        return 1;
}


int
main()
{
        printf("main process group: %ld\n", getpgrp());
        pid_t child = fork();
        if (child == 0)
                return child1();

        pid_t pid;
        do {
                int childStatus = -1;
                pid = waitpid(0, &childStatus, 0);
                printf("waitpid() returned %ld (%s), child status %d\n", pid, strerror(errno), childStatus);
        } while (pid >= 0);

        return 0;
}