Add bootstrap::signal function to connect to system-wide signals of interest

Connect to logout signal and clear upgrader session on staff logout.

bootstrap.php

@@ -48,6 +48,20 @@ class Bootstrap {
             $_SERVER['REMOTE_ADDR'] = '';
     }
 
+    /*
+     * Glue to global signals  we're interested in
+     */
+    static function signals() {
+
+        //Clear upgrader session on logout.
+        Signal::connect('auth.logout', function ($user, $data=null) {
+                    if (!$user) return;
+
+                    if ($user instanceof Staff)
+                        $_SESSION['ost_upgrader'] = null;
+                });
+    }
+
     function https() {
        return
             (isset($_SERVER['HTTPS'])

include/class.auth.php

@@ -303,6 +303,7 @@ abstract class StaffAuthenticationBackend  extends AuthenticationBackend {
                     $staff->getUserName(),
                     $_SERVER['REMOTE_ADDR'])); //Debug.
 
+        Signal::send('auth.logout', $staff);
     }
 
     static function getUser() {

main.inc.php

@@ -26,6 +26,7 @@ Bootstrap::defineTables(TABLE_PREFIX);
 Bootstrap::i18n_prep();
 Bootstrap::loadCode();
 Bootstrap::connect();
+Bootstrap::signals();
 
 if(!($ost=osTicket::start()) || !($cfg = $ost->getConfig()))
 Bootstrap::croak('Unable to load config info from DB. Get tech support.');