void func(char *data)
{
  char buffer[5];
  strcpy(buffer, data);
}

int main(int argc, char *argv[], char *envp[])
{
  int i;

  // clearing out the stack memory
  // clearing all arguments except the first and second
  memset(argv[0], 0, strlen(argv[0]));
  for(i=3; argv[i] != 0; i++)
    memset(argv[i], 0, strlen(argv[i]));
  // clearing all environment variables
  for(i=0; envp[i] != 0; i++)
    memset(envp[i], 0, strlen(envp[i]));

  // If the first argument is too long, exit
  if(strlen(argv[1]) > 40)
  {
    printf("first arg is too long.\n");
    exit(1);
  }

  if(argc > 2)
  {
    printf("arg2 is at %p\n", argv[2]);
    for(i=0; i < strlen(argv[2])-1; i++)
    {
      if(!(isprint(argv[2][i])))
      {
        // If there are any nonprintable characters in the
        // second argument, exit
        printf("only printable characters are allowed!\n");
        exit(1);
      }
    }
  }
  func(argv[1]);
  return 0;
}