o/devicestate: raise conflict when requesting system action while seeding

overlord/devicestate/devicemgr.go

@@ -818,6 +818,14 @@ var ErrUnsupportedAction = errors.New("unsupported action")
 // system reboot will be requested when the request can be successfully carried
 // out.
 func (m *DeviceManager) RequestSystemAction(systemLabel string, action SystemAction) error {
+	if systemLabel == "" {
+		return fmt.Errorf("internal error: system label is unset")
+	}
+	if m.systemMode == "" {
+		// uc16/uc18 have no mode
+		return ErrUnsupportedAction
+	}
+
 	if err := checkSystemRequestConflict(m.state, systemLabel); err != nil {
 		return err
 	}

overlord/devicestate/devicestate_systems_test.go

@@ -549,6 +549,11 @@ func (s *deviceMgrSystemsSuite) TestRequestModeNonUC20(c *C) {
 	c.Check(s.restartRequests, HasLen, 0)
 }
 
+func (s *deviceMgrSystemsSuite) TestRequestActionNoLabel(c *C) {
+	err := s.mgr.RequestSystemAction("", devicestate.SystemAction{Mode: "install"})
+	c.Assert(err, ErrorMatches, "internal error: system label is unset")
+}
+
 func (s *deviceMgrSystemsSuite) TestRequestModeForNonCurrent(c *C) {
 	s.state.Lock()
 	s.state.Set("seeded-systems", []devicestate.SeededSystem{
@@ -590,3 +595,39 @@ func (s *deviceMgrSystemsSuite) TestRequestInstallForOther(c *C) {
 	// reinstall from different system seed is ok
 	s.testRequestModeWithRestart(c, []string{"install"}, s.mockedSystemSeeds[1].label)
 }
+
+func (s *deviceMgrSystemsSuite) TestRequestAction1618(c *C) {
+	s.setPCModelInState(c)
+	// system mode is unset in 16/18
+	devicestate.SetSystemMode(s.mgr, "")
+	// no modeenv either
+	err := os.Remove(dirs.SnapModeenvFileUnder(dirs.GlobalRootDir))
+	c.Assert(err, IsNil)
+
+	s.state.Lock()
+	s.state.Set("seeded-systems", nil)
+	s.state.Set("seeded", nil)
+	s.state.Unlock()
+	// a label exists
+	err = s.mgr.RequestSystemAction(s.mockedSystemSeeds[0].label, devicestate.SystemAction{Mode: "install"})
+	c.Assert(err, Equals, devicestate.ErrUnsupportedAction)
+
+	s.state.Lock()
+	s.state.Set("seeded", true)
+	s.state.Unlock()
+
+	// even with system mode explicitly set, the action is not executed
+	devicestate.SetSystemMode(s.mgr, "run")
+
+	err = s.mgr.RequestSystemAction(s.mockedSystemSeeds[0].label, devicestate.SystemAction{Mode: "install"})
+	c.Assert(err, ErrorMatches, "cannot set device to boot .*: system mode is unsupported")
+
+	devicestate.SetSystemMode(s.mgr, "")
+	// also no UC20 style system seeds
+	for _, m := range s.mockedSystemSeeds {
+		os.RemoveAll(filepath.Join(dirs.SnapSeedDir, "systems", m.label))
+	}
+
+	err = s.mgr.RequestSystemAction(s.mockedSystemSeeds[0].label, devicestate.SystemAction{Mode: "install"})
+	c.Assert(err, Equals, devicestate.ErrUnsupportedAction)
+}