    public function getChart($renderer, $id, $store_in_session = true)
    {
        $c          = null;
        $chart_data = null;
        if ($renderer != null && $store_in_session) {
            $session = new Tracker_Report_Session($renderer->report->id);
            $session->changeSessionNamespace("renderers.{$renderer->id}");

            // look for the chart in the session
            $chart_data = $session->get("charts.$id");
        }

        if (! $chart_data) {
            // not found. look in the db
            $dao        = new GraphOnTrackersV5_ChartDao(CodendiDataAccess::instance());
            $chart_data = $dao->searchById($id)->getRow();
        }

        if ($chart_data) {
            if (! $renderer) {
                $report   = null; //We don't know the report
                $renderer = Tracker_Report_RendererFactory::instance()->getReportRendererById($chart_data['report_graphic_id'], $report, $store_in_session);
            }
            if ($renderer) {
                $c = $this->instanciateChart($chart_data, $renderer, $store_in_session);
            }
        }
        return $c;
    }
The software does not perform an authorization check when an actor attempts to access a resource or perform an action.