if int64(p) == -1 {
		return pos, errnoErr2(e1, e2)
	}
	return pos, nil
}

// FcntlFlock performs a fcntl syscall for the F_GETLK, F_SETLK or F_SETLKW command.
func FcntlFlock(fd uintptr, cmd int, lk *Flock_t) error {
	// struct flock is packed on z/OS. We can't emulate that in Go so
	// instead we pack it here.
	var flock [24]byte
	*(*int16)(unsafe.Pointer(&flock[0])) = lk.Type