Fix the varlink upgraded calls

Although an upgraded call is requested, the server has to send at least
one reply (can be an error) and the client has to check the reply,
before assuming an upgraded connection.

Signed-off-by: Harald Hoyer <harald@redhat.com>

pkg/adapter/containers_remote.go

@@ -583,7 +583,15 @@ func (r *LocalRuntime) attach(ctx context.Context, stdin, stdout *os.File, cid s
 
 	}
 	// TODO add detach keys support
-	_, err = iopodman.Attach().Send(r.Conn, varlink.Upgrade, cid, detachKeys, start)
+	reply, err := iopodman.Attach().Send(r.Conn, varlink.Upgrade, cid, detachKeys, start)
+	if err != nil {
+		restoreTerminal(oldTermState)
+		return nil, err
+	}
+
+	// See if the server accepts the upgraded connection or returns an error
+	_, err = reply()
+
 	if err != nil {
 		restoreTerminal(oldTermState)
 		return nil, err

pkg/varlinkapi/attach.go

@@ -60,7 +60,10 @@ func (i *LibpodAPI) Attach(call iopodman.VarlinkCall, name string, detachKeys st
 	if !start && state != libpod.ContainerStateRunning {
 		return call.ReplyErrorOccurred("container must be running to attach")
 	}
-	call.Reply(nil)
+
+	// ACK the client upgrade request
+	call.ReplyAttach()
+
 	reader, writer, _, pw, streams := setupStreams(call)
 
 	go func() {

pkg/varlinkapi/transfers.go

@@ -29,6 +29,12 @@ func (i *LibpodAPI) SendFile(call iopodman.VarlinkCall, ftype string, length int
 		return call.ReplyErrorOccurred(err.Error())
 	}
 
+	// FIXME return parameter
+	if err = call.ReplySendFile("FIXME_file_handle"); err != nil {
+		// If an error occurs while sending the reply, return the error
+		return err
+	}
+
 	writer := bufio.NewWriter(outputFile)
 	defer writer.Flush()
 
@@ -60,9 +66,10 @@ func (i *LibpodAPI) ReceiveFile(call iopodman.VarlinkCall, filepath string, dele
 	}
 
 	// Send the file length down to client
-	// Varlink connection upraded
+	// Varlink connection upgraded
 	if err = call.ReplyReceiveFile(fileInfo.Size()); err != nil {
-		return call.ReplyErrorOccurred(err.Error())
+		// If an error occurs while sending the reply, return the error
+		return err
 	}
 
 	reader := bufio.NewReader(fs)