/**
 * This program forks a separate process using the fork()/exec() system calls.
 *
 * Figure 3.10
 *
 * @author Gagne, Galvin, Silberschatz
 * Operating System Concepts  - Seventh Edition
 * Copyright John Wiley & Sons - 2005.
 */

#define _GNU_SOURCE

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


int
main (int argc, char **argv)
{
  int n = 0, *m;
  pid_t pid;

  m = (int *) malloc(sizeof(int));
  *m = 2;

  pid = fork ();
  
  if (pid < 0)
    {				/* error occurred */
      fprintf (stderr, "Fork Failed\n");
      exit (-1);		/* Get out. */
    }
  else if (pid == 0)
    {				/* child process */
      printf ("** I am the child, my pid value: %d: n=%d; *m=%d; m's addr: %x**\n", pid, n, *m, m);
      n = 24;
      *m = 31;
      printf ("** I am the child, my pid value: %d: n=%d; *m=%d; **\n", pid, n, *m);
      
      exit(0);
      
    }
  else
    {				/* parent process */

      wait (NULL);
      printf ("Child Complete\n");

      /* parent will wait for the child to complete */
      n = 45;
      printf ("** I am the parent; child's %d: n=%d; *m=%d; m's addr: %x **\n", pid, n, *m, m);

      exit (0);
    }
}