/* 	pipedemo.c -- Parent/child processes communication via a pipe
 *      Using a pipe to send data from a parent to a child process
 *	John Gray, Interprocess Communications in UNIX,  P.125
 */
#include 	<stdio.h>
#include	<signal.h>
#include	<unistd.h>
#include	<stdlib.h>
#include 	<string.h>
int 
main(int argc, char *argv[]){
  int	f_des[2];
  static char	message[BUFSIZ];
  if (argc != 2){
    fprintf(stderr, "Usage: %s message\n", *argv); exit(1);
  }
  if (pipe(f_des) == -1){   /* generate the pipe */
    perror("pipe");  exit(2);
  }
  switch (fork() ) {
    case -1:
      perror("Fork");
      exit(3);
    case 0:        /* In the child */
      close(f_des[1]);
      sleep(1); 	
      printf("My Mommy's pid is %d\n",getppid());
      if (read(f_des[0], message, BUFSIZ) != -1) {
       	printf("Message received by child: [%s]\n", message);
	fflush(stdout);
      } else {
        perror("Read");  exit(4);
      }
      break;
     default:
	close(f_des[0]);
	if (write(f_des[1], argv[1], strlen(argv[1])) !=-1) {
	  printf("Message sent by parent: [%s]\n", argv[1]);
	  fflush(stdout);
	} else {
	  perror("Write");  exit (5);
	}
  }
  exit(0);
}