Fix unblocking after closing listener

listener_linux.go

@@ -83,6 +83,10 @@ func listenStreamLinux(lfd fd, cid, port uint32) (net.Listener, error) {
 		Port: port,
 	}
 
+	if err := lfd.SetNonblock(true); err != nil {
+		return nil, err
+	}
+
 	if err := lfd.Bind(sa); err != nil {
 		return nil, err
 	}

listener_linux_test.go

@@ -10,7 +10,11 @@ import (
 )
 
 func Test_listenStreamLinuxHandleError(t *testing.T) {
-	var closed bool
+	var (
+		closed      bool
+		nonblocking bool
+	)
+
 	lfd := &testFD{
 		// Track when fd.Close is called.
 		close: func() error {
@@ -21,12 +25,21 @@ func Test_listenStreamLinuxHandleError(t *testing.T) {
 		bind: func(sa unix.Sockaddr) error {
 			return errors.New("error during bind")
 		},
+		setNonblock: func(n bool) error {
+			nonblocking = n
+			return nil
+		},
 	}
 
 	if _, err := listenStreamLinuxHandleError(lfd, 0, 0); err == nil {
 		t.Fatal("expected an error, but none occurred")
 	}
 
+	if want, got := true, nonblocking; want != got {
+		t.Fatalf("unexpected nonblocking value:\n- want: %v\n-  got: %v",
+			want, got)
+	}
+
 	if want, got := true, closed; want != got {
 		t.Fatalf("unexpected socket close value:\n- want: %v\n-  got: %v",
 			want, got)
@@ -58,6 +71,7 @@ func Test_listenStreamLinuxPortZero(t *testing.T) {
 		bind:        bindFn,
 		listen:      func(n int) error { return nil },
 		getsockname: func() (unix.Sockaddr, error) { return lsa, nil },
+		setNonblock: func(n bool) error { return nil },
 	}
 
 	if _, err := listenStreamLinux(lfd, cid, port); err != nil {

vsock_test.go

@@ -1,6 +1,10 @@
 package vsock
 
-import "testing"
+import (
+	"sync"
+	"testing"
+	"time"
+)
 
 func TestAddr_fileName(t *testing.T) {
 	tests := []struct {
@@ -44,3 +48,45 @@ func TestAddr_fileName(t *testing.T) {
 		})
 	}
 }
+
+func TestUnblockAcceptAfterClose(t *testing.T) {
+	listener, err := Listen(1024)
+	if err != nil {
+		t.Fatalf("failed to run listener: %v", err)
+	}
+
+	var wg sync.WaitGroup
+
+	wg.Add(1)
+
+	go func() {
+		defer wg.Done()
+
+		t.Log("start accept")
+		_, err := listener.Accept()
+		t.Log("after accept")
+		if err != nil {
+			return
+		}
+	}()
+
+	time.Sleep(1 * time.Second)
+
+	if err := listener.Close(); err != nil {
+		t.Fatalf("failed to close listener: %v", err)
+	}
+
+	done := make(chan bool)
+	go func() {
+		wg.Wait()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		t.Log("done")
+		return
+	case <-time.After(5 * time.Second):
+		t.Fatal("timeout waiting accept to unblock")
+	}
+}