func (c *TCPConn) SyscallConn() (syscall.RawConn, error) {
	if !c.ok() {
		return nil, syscall.EINVAL
	}
	return newRawConn(c.fd), nil
}

// ReadFrom implements the [io.ReaderFrom] ReadFrom method.
func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.readFrom(r)
	if err != nil && err != io.EOF {

// The best way is to return EINVAL and let Golang handles its failure
// If the syscall can't fail, this function can redirect it to a real syscall.
//
// This is exported via linkname to assembly in the syscall package.
//
//go:nosplit
//go:linkname syscall_Syscall
func syscall_Syscall(fn, a1, a2, a3 uintptr) (r1, r2, err uintptr) {
	return 0, 0, _EINVAL
}

		return os.NewSyscallError("setReadBuffer", syscall.EINVAL)
	}
	ffd.queue.setReadBuffer(bytes)
	return nil
}

func (ffd *fakeNetFD) setWriteBuffer(bytes int) error {
	return os.NewSyscallError("setWriteBuffer", syscall.ENOTSUP)
}

func (ffd *fakeNetFD) setLinger(sec int) error {
	if sec < 0 || ffd.peer == nil {
		return os.NewSyscallError("setLinger", syscall.EINVAL)
	}
	ffd.peer.queue.setLinger(sec > 0)

func (c *IPConn) SyscallConn() (syscall.RawConn, error) {
	if !c.ok() {
		return nil, syscall.EINVAL
	}
	return newRawConn(c.fd), nil
}

// ReadFromIP acts like ReadFrom but returns an IPAddr.
func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
	if !c.ok() {
		return 0, nil, syscall.EINVAL
	}
	n, addr, err := c.readFrom(b)
	if err != nil {

}

var finVar struct {
	sync.Mutex
	cnt int
}

func TestNoRaceFinGlobal(t *testing.T) {
	c := make(chan bool)
	go func() {
		x := new(string)
		runtime.SetFinalizer(x, func(x *string) {
			finVar.Lock()
			finVar.cnt++
			finVar.Unlock()
		})
		c <- true
	}()
	<-c
	runtime.GC()
	time.Sleep(100 * time.Millisecond)
	finVar.Lock()
	finVar.cnt++
	finVar.Unlock()
}

	"syscall"
)

func (out *OutBuf) fallocate(size uint64) error {
	err := unix.PosixFallocate(int(out.f.Fd()), 0, int64(size))
	// ZFS on FreeBSD does not support posix_fallocate and returns EINVAL in that case.
	if err == syscall.EINVAL {
		return errNoFallocate
	}
	return err

	}
	fd.Close()
	return nil, syscall.EINVAL
}

func fileListener(f *os.File) (Listener, error) {
	fd, err := newFileFD(f)
	if err != nil {
		return nil, err
	}
	switch laddr := fd.laddr.(type) {
	case *TCPAddr:
		return &TCPListener{fd: fd}, nil
	case *UnixAddr:
		return &UnixListener{fd: fd, path: laddr.Name, unlink: false}, nil
	}
	fd.Close()
	return nil, syscall.EINVAL
}

// integer array of open file descriptors from another process.
func ParseUnixRights(m *SocketControlMessage) ([]int, error) {
	if m.Header.Level != SOL_SOCKET {
		return nil, EINVAL
	}
	if m.Header.Type != SCM_RIGHTS {
		return nil, EINVAL
	}
	fds := make([]int, len(m.Data)>>2)
	for i, j := 0, 0; i < len(m.Data); i += 4 {
		fds[j] = int(*(*int32)(unsafe.Pointer(&m.Data[i])))
		j++
	}
	return fds, nil

func (ratVal) implementsValue()     {}
func (intVal) implementsValue()     {}
func (floatVal) implementsValue()   {}
func (complexVal) implementsValue() {}

func newInt() *big.Int     { return new(big.Int) }
func newRat() *big.Rat     { return new(big.Rat) }
func newFloat() *big.Float { return new(big.Float).SetPrec(prec) }

func i64toi(x int64Val) intVal   { return intVal{newInt().SetInt64(int64(x))} }

	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.writeToAddrPort(b, addr)
	if err != nil {
		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addrPortUDPAddr{addr}, Err: err}
	}
	return n, err
}

// WriteTo implements the PacketConn WriteTo method.
func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	a, ok := addr.(*UDPAddr)