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 {

func (p *Process) release() error {
	// Drop the Process' reference and mark handle unusable for
	// future calls.
	//
	// The API on Windows expects EINVAL if Release is called multiple
	// times.
	if old := p.handlePersistentRelease(statusReleased); old == statusReleased {
		return syscall.EINVAL
	}

	// no need for a finalizer anymore
	runtime.SetFinalizer(p, nil)
	return nil
}

func (p *Process) closeHandle() {

		if n > 0 {
			pos += int64(n)
			written += int64(n)
			remain -= int64(n)
		}
		if err == syscall.EINTR {
			continue
		}
		// This includes syscall.ENOSYS (no kernel
		// support) and syscall.EINVAL (fd types which
		// don't implement sendfile), and other errors.
		// We should end the loop when there is no error
		// returned from sendfile(2) or it is not a retryable error.
		if err != syscall.EAGAIN {
			break
		}

		if n > 0 {
			written += int64(n)
			remain -= int64(n)
			continue
		} else if err != syscall.EAGAIN && err != syscall.EINTR {
			// This includes syscall.ENOSYS (no kernel
			// support) and syscall.EINVAL (fd types which
			// don't implement sendfile), and other errors.
			// We should end the loop when there is no error
			// returned from sendfile(2) or it is not a retryable error.
			break
		}

func Stat(path string, st *Stat_t) error {
	if path == "" {
		return EINVAL
	}
	dirFd, pathPtr, pathLen := preparePath(path)
	errno := path_filestat_get(dirFd, LOOKUP_SYMLINK_FOLLOW, pathPtr, pathLen, unsafe.Pointer(st))
	setDefaultMode(st)
	return errnoErr(errno)
}

func Lstat(path string, st *Stat_t) error {
	if path == "" {
		return EINVAL
	}
	dirFd, pathPtr, pathLen := preparePath(path)

// SO_PASSCRED option must be enabled on the socket.
func ParseUnixCredentials(m *SocketControlMessage) (*Ucred, error) {
	if m.Header.Level != SOL_SOCKET {
		return nil, EINVAL
	}
	if m.Header.Type != SCM_CREDENTIALS {
		return nil, EINVAL
	}
	ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
	return &ucred, nil
}

// PktInfo4 encodes Inet4Pktinfo into a socket control message of type IP_PKTINFO.

	}
	if err := p.Release(); err != nil {
		t.Fatalf("first Release: got err %v, want nil", err)
	}

	err = p.Release()

	// We want EINVAL from a second Release call only on Windows.
	var want error
	if runtime.GOOS == "windows" {
		want = syscall.EINVAL
	}

	if err != want {
		t.Fatalf("second Release: got err %v, want %v", err, want)
	}

			pos += int64(n)
			written += int64(n)
			remain -= int64(n)
			continue
		} else if err != syscall.EAGAIN && err != syscall.EINTR {
			// This includes syscall.ENOSYS (no kernel
			// support) and syscall.EINVAL (fd types which
			// don't implement sendfile), and other errors.
			// We should end the loop when there is no error
			// returned from sendfile(2) or it is not a retryable error.
			break
		}

		t.Fatalf("syscall.open: %v", err)
	}
	defer syscall.Close(fd)

	buf := bytes.Repeat([]byte{0xCD}, direntBufSize)
	for {
		n, err := syscall.ReadDirent(fd, buf)
		if err == syscall.EINVAL {
			// On linux, 'man getdents64' says that EINVAL indicates “result buffer is too small”.
			// Try a bigger buffer.
			t.Logf("ReadDirent: %v; retrying with larger buffer", err)
			buf = bytes.Repeat([]byte{0xCD}, len(buf)*2)
			continue
		}

}

func Utimes(path string, tv []Timeval) (err error) {
	if len(tv) != 2 {
		return EINVAL
	}
	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
}

//sys	utimensat(dirfd int, path string, times *[2]Timespec, flag int) (err error)

func UtimesNano(path string, ts []Timespec) (err error) {
	if len(ts) != 2 {
		return EINVAL
	}
	return utimensat(_AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
}