tty: clean up epollConsole closing

ec0d23a ("tty: close epollConsole on errors") fixed a significant
issue, but the cleanup was not ideal (especially if the function is
changed in future to add additional error conditions to those currently
present). Using the defer-named-error trick avoids this issue and makes
the code more readable.

Signed-off-by: Aleksa Sarai <asarai@suse.de>

tty.go

@@ -71,7 +71,7 @@ func inheritStdio(process *libcontainer.Process) error {
 	return nil
 }
 
-func (t *tty) recvtty(process *libcontainer.Process, socket *os.File) error {
+func (t *tty) recvtty(process *libcontainer.Process, socket *os.File) (Err error) {
 	f, err := utils.RecvFd(socket)
 	if err != nil {
 		return err
@@ -89,6 +89,11 @@ func (t *tty) recvtty(process *libcontainer.Process, socket *os.File) error {
 	if err != nil {
 		return err
 	}
+	defer func() {
+		if Err != nil {
+			epollConsole.Close()
+		}
+	}()
 	go epoller.Wait()
 	go io.Copy(epollConsole, os.Stdin)
 	t.wg.Add(1)
@@ -97,11 +102,9 @@ func (t *tty) recvtty(process *libcontainer.Process, socket *os.File) error {
 	// set raw mode to stdin and also handle interrupt
 	stdin, err := console.ConsoleFromFile(os.Stdin)
 	if err != nil {
-		epollConsole.Close()
 		return err
 	}
 	if err := stdin.SetRaw(); err != nil {
-		epollConsole.Close()
 		return fmt.Errorf("failed to set the terminal from the stdin: %v", err)
 	}
 	go handleInterrupt(stdin)