/**

 * pipe.c

 * Copyright (C) 2009 Markus Broeker

 */

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/wait.h>

#include <assert.h>

#define MAX 50

int main (int argc, char **argv)

{

    int tube[2];

    int i, status, count = 0;

    pid_t pid;

    char buffer[80];

    for (i = 0; i < MAX; i++) {

        if (pipe (tube) == -1) {

            perror ("PIPE");

            return EXIT_FAILURE;

        }

        pid = fork ();

        switch (pid) {

        case 0:

            // we only want to write

            close (tube[0]);

            /**

             * copy on write: every forked process gets its own copy of i

             *                and the magic of synchronization works

             */

            for (i = 0; i < MAX; i++)

                status = write (tube[1], "MESSAGE FROM SON\n", 17);

            break;

        case -1:

            printf ("ERROR");

            break;

        default:

            printf ("Son started as pid %d\n", pid);

            // we only want to read...

            close (tube[1]);

            FILE *f = fdopen (tube[0], "r");

            assert (f != NULL);

            while (fgets (buffer, sizeof (buffer), f) != NULL) {

                printf ("FATHER RECEIVED [%4d]: %s", count++, buffer);

            }

            if (fclose (f) < 0)

                perror ("fclose");

            printf ("PID [%4d] has finished...\n", wait (&pid));

        }

    }

    return EXIT_SUCCESS;

}