machine1: add a method ListMachines

Add a DBUS method for `ListMachines` that lists all active machines.

Author: Dongsu Park

machine1/dbus.go

@@ -37,6 +37,14 @@ type Conn struct {
 	object dbus.BusObject
 }
 
+// MachineStatus is a set of necessary info for each machine
+type MachineStatus struct {
+	Name    string          // The primary machine name as string
+	Class   string          // The machine class as string
+	Service string          // The machine service as string
+	JobPath dbus.ObjectPath // The job object path
+}
+
 // New() establishes a connection to the system bus and authenticates.
 func New() (*Conn, error) {
 	c := new(Conn)
@@ -139,3 +147,47 @@ func (c *Conn) TerminateMachine(name string) error {
 func (c *Conn) RegisterMachine(name string, id []byte, service string, class string, pid int, root_directory string) error {
 	return c.object.Call(dbusInterface+".RegisterMachine", 0, name, id, service, class, uint32(pid), root_directory).Err
 }
+
+func machineFromInterfaces(machine []interface{}) (*MachineStatus, error) {
+	if len(machine) < 4 {
+		return nil, fmt.Errorf("invalid number of machine fields: %d", len(machine))
+	}
+	name, ok := machine[0].(string)
+	if !ok {
+		return nil, fmt.Errorf("failed to typecast machine field 0 to string")
+	}
+	class, ok := machine[1].(string)
+	if !ok {
+		return nil, fmt.Errorf("failed to typecast class field 1 to string")
+	}
+	service, ok := machine[2].(string)
+	if !ok {
+		return nil, fmt.Errorf("failed to typecast service field 2 to string")
+	}
+	jobpath, ok := machine[3].(dbus.ObjectPath)
+	if !ok {
+		return nil, fmt.Errorf("failed to typecast jobpath field 3 to ObjectPath")
+	}
+
+	ret := MachineStatus{Name: name, Class: class, Service: service, JobPath: jobpath}
+	return &ret, nil
+}
+
+// ListMachines returns an array of all currently running machines.
+func (c *Conn) ListMachines() ([]MachineStatus, error) {
+	result := make([][]interface{}, 0)
+	if err := c.object.Call(dbusInterface+".ListMachines", 0).Store(&result); err != nil {
+		return nil, err
+	}
+
+	machs := []MachineStatus{}
+	for _, i := range result {
+		machine, err := machineFromInterfaces(i)
+		if err != nil {
+			return nil, err
+		}
+		machs = append(machs, *machine)
+	}
+
+	return machs, nil
+}

machine1/dbus_test.go

@@ -80,6 +80,16 @@ func TestMachine(t *testing.T) {
 		t.Fatalf("did not find machine named %s", machineName)
 	}
 
+	listMachines, getErr := conn.ListMachines()
+	if getErr != nil {
+		t.Fatal(getErr)
+	}
+
+	// listMachines includes also `.host`, so by default the length should be greater than 1
+	if len(listMachines) <= 1 {
+		t.Fatalf("did not find any machine")
+	}
+
 	tErr := conn.TerminateMachine(machineName)
 	if tErr != nil {
 		t.Fatal(tErr)