qmp: add query-status API

So that caller can find out guest status via qmp.

Signed-off-by: Peng Tao <bergwolf@hyper.sh>

qemu/qmp.go

@@ -251,6 +251,13 @@ type SchemaInfo struct {
 	Name     string `json:"name"`
 }
 
+// StatusInfo represents guest running status
+type StatusInfo struct {
+	Running    bool   `json:"running"`
+	SingleStep bool   `json:"singlestep"`
+	Status     string `json:"status"`
+}
+
 func (q *QMP) readLoop(fromVMCh chan<- []byte) {
 	scanner := bufio.NewScanner(q.conn)
 	if q.cfg.MaxCapacity > 0 {
@@ -1545,3 +1552,23 @@ func (q *QMP) ExecQueryQmpSchema(ctx context.Context) ([]SchemaInfo, error) {
 
 	return schemaInfo, nil
 }
+
+// ExecuteQueryStatus queries guest status
+func (q *QMP) ExecuteQueryStatus(ctx context.Context) (StatusInfo, error) {
+	response, err := q.executeCommandWithResponse(ctx, "query-status", nil, nil, nil)
+	if err != nil {
+		return StatusInfo{}, err
+	}
+
+	data, err := json.Marshal(response)
+	if err != nil {
+		return StatusInfo{}, fmt.Errorf("unable to extract migrate status information: %v", err)
+	}
+
+	var status StatusInfo
+	if err = json.Unmarshal(data, &status); err != nil {
+		return StatusInfo{}, fmt.Errorf("unable to convert migrate status information: %v", err)
+	}
+
+	return status, nil
+}

qemu/qmp_test.go

@@ -1623,3 +1623,30 @@ func TestQMPExecQueryQmpSchema(t *testing.T) {
 	q.Shutdown()
 	<-disconnectedCh
 }
+
+func TestQMPExecQueryQmpStatus(t *testing.T) {
+	connectedCh := make(chan *QMPVersion)
+	disconnectedCh := make(chan struct{})
+	buf := newQMPTestCommandBuffer(t)
+	statusInfo := StatusInfo{
+		Running:    true,
+		SingleStep: false,
+		Status:     "running",
+	}
+	buf.AddCommand("query-status", nil, "return", statusInfo)
+	cfg := QMPConfig{
+		Logger:      qmpTestLogger{},
+		MaxCapacity: 1024,
+	}
+	q := startQMPLoop(buf, cfg, connectedCh, disconnectedCh)
+	checkVersion(t, connectedCh)
+	info, err := q.ExecuteQueryStatus(context.Background())
+	if err != nil {
+		t.Fatalf("Unexpected error: %v\n", err)
+	}
+	if reflect.DeepEqual(info, statusInfo) == false {
+		t.Fatalf("Expected %v equals to %v\n", info, statusInfo)
+	}
+	q.Shutdown()
+	<-disconnectedCh
+}