int serrno = errno;
int save_errno = errno;
unlockpt (fd)     int fd __attribute__ ((unused));{#ifdef TIOCSPTLCK  int serrno = errno;  int unlock = 0;  if (__ioctl (fd, TIOCSPTLCK, &unlock))    {      if (errno == EINVAL)	{	  __set_errno (serrno);	  return 0;	}      else	return -1;    }#endif  /* On pre-/dev/ptmx kernels this function should be a no-op.  */  return 0;}