perror ("closedir"); exit (1);
puts ("could not close directory file descriptor");  return 0;
main (void){  DIR *dirp;  struct dirent* ent;  /* open a dir stream */  dirp = opendir ("/tmp");  if (dirp == NULL)    {      if (errno == ENOENT)	exit (0);      perror ("opendir");      exit (1);    }  /* close the dir stream, making it invalid */  if (closedir (dirp))    {      perror ("closedir");      exit (1);    }  ent = readdir (dirp);  return ent != NULL || errno != EBADF;}