/**
 * This program creates a new process and provides a simple pipe to
 * allow the child to communicate with the parent
 * Version 1 -- explicitly using pipe and byte-oriented read/write
 * type 'quit' to exit program
 */

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

 // Maximum number of letters to be communicated
 #define MAX 40

 int main() {
   // File descriptor array for the pipe
   // * fd[0] will be the end you can read from
   // * fd[1] will be the end you can write to
   int fd[2];

   // Character array (string) for reading
   char line[MAX];
   char input[MAX];

   pid_t pid;

   // Create a pipe and check for errors
   if(pipe(fd) == -1) {
	 perror("pipe error");
	 exit(EXIT_FAILURE);
   }

   // Fork a child process and check for errors
   pid = fork();
   if(pid == -1) {
	 perror("error in fork");
	 exit(EXIT_FAILURE);
   }

   if(pid == 0) {
	 // Processing for the child process only
	 printf("The child process is active.\n");

	 // Close the writable end of the pipe, leaving the readable end open
	 close(fd[0]);

	 // Write a string to the pipe and indicate its length (in bytes)

	 do {
	   scanf("%s", input);
	   write(fd[1], input, 26);
	 } while (strcmp(line, "quit") != 0);

   } else {
	 // Processing for the parent process only
	 printf("The parent process is active.\n");

	 // Close the readable end of the pipe, leaving the writable end open
	 close(fd[1]);

	 // Read from the pipe
	 do
	 {
	   read(fd[0], line, MAX);
	   printf("recieved %s\n", line);
	 } while (strcmp(line, "quit") != 0);
   }

   exit(EXIT_SUCCESS);
 }