//sys fcntl(fd int, cmd int, arg int) (val int, err error)
//sys fcntlPtr(fd int, cmd int, arg unsafe.Pointer) (val int, err error) = SYS_FCNTL
+//sysnb ioctl(fd int, req int, arg int) (err error)
+//sysnb ioctlPtr(fd int, req uint, arg unsafe.Pointer) (err error) = SYS_IOCTL
var mapper = &mmapper{
active: make(map[*byte][]byte),