#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>

int pipe_fd[2];

void do_child(void)
{
        char *p = "Hello, dad or mam!\n";

        printf("This is child.\n");

        close(pipe_fd[0]);

        while (*p != '\0') {
                if (write(pipe_fd[1], p, 1) < 0) {
                        perror("write");
                        exit(1);
                }
                p++;
        }
}

void do_parent(void)
{
        char c;
        int count, status;

        printf("This is parent.\n");

        close(pipe_fd[1]);

        while ((count = read(pipe_fd[0], &c, 1)) > 0) {
                putchar(c);
        }

        if (count < 0) {
                perror("read");
                exit(1);
        }

        if (wait(&status) < 0) {
                perror("wait");
                exit(1);
        }
}

int main(void)
{
        int child;

        if (pipe(pipe_fd) < 0) {
                perror("pipe");
                exit(1);
        }

        if ((child = fork()) < 0) {
                perror("fork");
                exit(1);
        }

        if (child) {
                do_parent();
        } else {
                do_child();
        }

        return 0;
}