Fix TestIfSocketCloses

nl/nl_linux_test.go

@@ -7,6 +7,7 @@ import (
 	"reflect"
 	"testing"
 	"time"
+	_ "unsafe"
 
 	"golang.org/x/sys/unix"
 )
@@ -63,6 +64,9 @@ func TestIfInfomsgDeserializeSerialize(t *testing.T) {
 	testDeserializeSerialize(t, orig, safemsg, msg)
 }
 
+//go:linkname errFileClosing internal/poll.ErrFileClosing
+var errFileClosing error
+
 func TestIfSocketCloses(t *testing.T) {
 	nlSock, err := Subscribe(unix.NETLINK_ROUTE, unix.RTNLGRP_NEIGH)
 	if err != nil {
@@ -74,8 +78,7 @@ func TestIfSocketCloses(t *testing.T) {
 		endCh <- nil
 		for {
 			_, _, err := sk.Receive()
-			// Receive returned because of a timeout and the FD == -1 means that the socket got closed
-			if err == unix.EAGAIN && nlSock.GetFd() == -1 {
+			if err == errFileClosing {
 				endCh <- err
 				return
 			}