Merge pull request coreos#385 from dylanratcliffe/get-unit-pid

dbus: add support for querying unit by PID

dbus/methods.go

@@ -417,6 +417,29 @@ func (c *Conn) listUnitsInternal(f storeFunc) ([]UnitStatus, error) {
 	return status, nil
 }
 
+// GetUnitByPID returns the unit object path of the unit a process ID
+// belongs to. It takes a UNIX PID and returns the object path. The PID must
+// refer to an existing system process
+func (c *Conn) GetUnitByPID(ctx context.Context, pid uint32) (dbus.ObjectPath, error) {
+	var result dbus.ObjectPath
+
+	err := c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.GetUnitByPID", 0, pid).Store(&result)
+
+	return result, err
+}
+
+// GetUnitNameByPID returns the name of the unit a process ID belongs to. It
+// takes a UNIX PID and returns the object path. The PID must refer to an
+// existing system process
+func (c *Conn) GetUnitNameByPID(ctx context.Context, pid uint32) (string, error) {
+	path, err := c.GetUnitByPID(ctx, pid)
+	if err != nil {
+		return "", err
+	}
+
+	return unitName(path), nil
+}
+
 // Deprecated: use ListUnitsContext instead.
 func (c *Conn) ListUnits() ([]UnitStatus, error) {
 	return c.ListUnitsContext(context.Background())

dbus/methods_test.go

@@ -450,6 +450,38 @@ func TestReloadOrRestartUnit(t *testing.T) {
 	}
 }
 
+// Ensure that GetUnitByPID works.
+func TestGetUnitByPID(t *testing.T) {
+	conn := setupConn(t)
+	defer conn.Close()
+
+	path, err := conn.GetUnitByPID(context.Background(), 1)
+
+	if err != nil {
+		t.Error(err)
+	}
+
+	if path == "" {
+		t.Fatal("path is empty")
+	}
+}
+
+// Ensure that GetUnitNameByPID works.
+func TestGetUnitNameByPID(t *testing.T) {
+	conn := setupConn(t)
+	defer conn.Close()
+
+	name, err := conn.GetUnitNameByPID(context.Background(), 1)
+
+	if err != nil {
+		t.Error(err)
+	}
+
+	if name == "" {
+		t.Fatal("name is empty")
+	}
+}
+
 // Ensure that ListUnitsByNames works.
 func TestListUnitsByNames(t *testing.T) {
 	target1 := "systemd-journald.service"