#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

int
main()
{
    int pipe_ends[2];
    if (pipe(pipe_ends) == -1)
        perror("pipe"), exit(-1);
    
    int child = fork();
    if (child == -1)
        perror("fork"), exit(-1);

    if (child == 0) {
        char msg[] = { "Hi\n" };

        close(pipe_ends[0]);
        write(pipe_ends[1], msg, sizeof msg);
        printf("Child done\n");

    } else {
        char bread, pipe_buf[128];

        close(pipe_ends[1]);
        sleep(1);
        
        printf("Child said ");
        // ensure that stdout buffer is flushed before
        // calling write(1, )
        fflush(stdout);
        while ((bread = read(pipe_ends[0], pipe_buf, sizeof pipe_buf)) > 0)
            write(1, pipe_buf, bread);
    }
}