}
	// The kernel expects seconds so round to next highest second.
	secs := int(roundDurationUp(d, time.Second))
	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_TCP, sysTCP_KEEPIDLE, secs)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setKeepAliveInterval(fd *netFD, d time.Duration) error {
	if !unix.SupportTCPKeepAliveIdleIntvlCNT() {
		return syscall.EPROTOTYPE
	}

	if d == 0 {

	runtime.KeepAlive(fd)
	return wrapSyscallError("shutdown", err)
}

func (fd *netFD) closeRead() error {
	return fd.shutdown(syscall.SHUT_RD)
}

func (fd *netFD) closeWrite() error {
	return fd.shutdown(syscall.SHUT_WR)
}

func (fd *netFD) Read(p []byte) (n int, err error) {
	n, err = fd.pfd.Read(p)
	runtime.KeepAlive(fd)
	return n, wrapSyscallError(readSyscallName, err)
}

	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setIPv6MulticastInterface(fd *netFD, ifi *Interface) error {
	var v int
	if ifi != nil {
		v = ifi.Index
	}
	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_IPV6, syscall.IPV6_MULTICAST_IF, v)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setKeepAliveCount(fd *netFD, n int) error {
	if n == 0 {
		n = defaultTCPKeepAliveCount
	} else if n < 0 {
		return nil
	}

	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_TCP, sysTCP_KEEPCNT, n)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)

	err := fd.pfd.SetsockoptInt(syscall.SOL_SOCKET, syscall.SO_RCVBUF, bytes)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setWriteBuffer(fd *netFD, bytes int) error {
	err := fd.pfd.SetsockoptInt(syscall.SOL_SOCKET, syscall.SO_SNDBUF, bytes)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setKeepAlive(fd *netFD, keepalive bool) error {

	err = fd.pfd.SetsockoptInet4Addr(syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, a)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setIPv4MulticastLoopback(fd *netFD, v bool) error {
	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_IP, syscall.IP_MULTICAST_LOOP, boolint(v))
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)

	ip, err := interfaceToIPv4Addr(ifi)
	if err != nil {
		return wrapSyscallError("setsockopt", err)
	}
	var a [4]byte
	copy(a[:], ip.To4())
	err = fd.pfd.SetsockoptInet4Addr(syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, a)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setIPv4MulticastLoopback(fd *netFD, v bool) error {

	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func setKeepAliveCount(fd *netFD, n int) error {
	if n == 0 {
		n = defaultTCPKeepAliveCount
	} else if n < 0 {
		return nil
	}

	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_TCP, syscall.TCP_KEEPCNT, n)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)

		return nil
	}
	err := fd.pfd.Shutdown(how)
	runtime.KeepAlive(fd)
	return wrapSyscallError("shutdown", err)
}

func (fd *netFD) Read(p []byte) (n int, err error) {
	if fd.fakeNetFD != nil {
		return fd.fakeNetFD.Read(p)
	}
	n, err = fd.pfd.Read(p)
	runtime.KeepAlive(fd)
	return n, wrapSyscallError(readSyscallName, err)
}

func (fd *netFD) Write(p []byte) (nn int, err error) {

	"internal/poll"
	"io"
	"syscall"
)

var (
	pollCopyFileRange = poll.CopyFileRange
	pollSplice        = poll.Splice
)

// wrapSyscallError takes an error and a syscall name. If the error is
// a syscall.Errno, it wraps it in an os.SyscallError using the syscall name.
func wrapSyscallError(name string, err error) error {
	if _, ok := err.(syscall.Errno); ok {
		err = NewSyscallError(name, err)
	}
	return err
}