runtime.KeepAlive(c.fd)
	if err != nil {
		err = &OpError{Op: "raw-control", Net: c.fd.net, Source: nil, Addr: c.fd.laddr, Err: err}
	}
	return err
}

func (c *rawConn) Read(f func(uintptr) bool) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	err := c.fd.pfd.RawRead(f)
	runtime.KeepAlive(c.fd)
	if err != nil {
		err = &OpError{Op: "raw-read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}

	case <-ctx.Done():
	case <-time.After(5 * time.Second):
		t.Fatal("expected context to be canceled")
	}

	oe, ok := err.(*OpError)
	if !ok || oe.Op != "dial" {
		t.Fatalf("Dial error = %#v; want dial *OpError", err)
	}

	if oe.Err != errCanceled {
		t.Errorf("DialContext = (%v, %v); want OpError with error %v", c, err, errCanceled)
	}

	if err != nil && err != io.EOF {
		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return n, err
}

// Write implements the Conn Write method.
func (c *conn) Write(b []byte) (int, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.fd.Write(b)
	if err != nil {

			t.Fatal(perr)
		}
	})
}

func parseReadError(nestedErr error, verify func(error) (string, bool)) error {
	err := nestedErr
	if nerr, ok := err.(*net.OpError); ok {
		err = nerr.Err
	}
	if nerr, ok := err.(*fs.PathError); ok {
		err = nerr.Err
	}
	if nerr, ok := err.(*os.SyscallError); ok {
		err = nerr.Err
	}
	if s, ok := verify(err); !ok {

func TestIsConnectionRefused(t *testing.T) {
	testCases := []struct {
		err    error
		expect bool
	}{
		{
			&url.Error{Err: &net.OpError{Err: syscall.ECONNRESET}},
			false,
		},
		{
			&url.Error{Err: &net.OpError{Err: syscall.ECONNREFUSED}},
			true,
		},
		{&url.Error{Err: &net.OpError{Err: &os.SyscallError{Err: syscall.ECONNREFUSED}}},
			true,
		},
	}

	for _, tc := range testCases {

	case *UnixAddr:
		la, _ := la.(*UnixAddr)
		c, err = sd.dialUnix(ctx, la, ra)
	default:
		return nil, &OpError{Op: "dial", Net: sd.network, Source: la, Addr: ra, Err: &AddrError{Err: "unexpected address type", Addr: sd.address}}
	}
	if err != nil {
		return nil, &OpError{Op: "dial", Net: sd.network, Source: la, Addr: ra, Err: err} // c is non-nil interface containing nil pointer
	}
	return c, nil
}

)

func isPlatformError(err error) bool {
	_, ok := err.(syscall.Errno)
	return ok
}

func samePlatformError(err, want error) bool {
	if op, ok := err.(*OpError); ok {
		err = op.Err
	}
	if sys, ok := err.(*os.SyscallError); ok {
		err = sys.Err
	}
	return err == want
}

func isENOBUFS(err error) bool {
	return errors.Is(err, syscall.ENOBUFS)

import (
	"runtime"
	"syscall"
)

func (c *conn) writeBuffers(v *Buffers) (int64, error) {
	if !c.ok() {
		return 0, syscall.EINVAL
	}
	n, err := c.fd.writeBuffers(v)
	if err != nil {
		return n, &OpError{Op: "writev", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return n, nil
}

func (fd *netFD) writeBuffers(v *Buffers) (n int64, err error) {
	n, err = fd.pfd.Writev((*[][]byte)(v))

	"io"
	"os"
	"os/exec"
	"regexp"
	"slices"
	"strings"
	"syscall"
	"testing"
	"time"
)

func toErrno(err error) (syscall.Errno, bool) {
	operr, ok := err.(*OpError)
	if !ok {
		return 0, false
	}
	syserr, ok := operr.Err.(*os.SyscallError)
	if !ok {
		return 0, false
	}
	errno, ok := syserr.Err.(syscall.Errno)
	if !ok {
		return 0, false
	}
	return errno, true
}

func (*pipe) RemoteAddr() Addr { return pipeAddr{} }

func (p *pipe) Read(b []byte) (int, error) {
	n, err := p.read(b)
	if err != nil && err != io.EOF && err != io.ErrClosedPipe {
		err = &OpError{Op: "read", Net: "pipe", Err: err}
	}
	return n, err
}

func (p *pipe) read(b []byte) (n int, err error) {
	switch {
	case isClosedChan(p.localDone):
		return 0, io.ErrClosedPipe