Add SystemPermissionException

This exception should be fired when the OS restricts the web user
from executing certain actions. Also the template for errors has
been modified so it displays the action and the target that
was prevented.

refs #4092

application/controllers/ErrorController.php

@@ -34,7 +34,6 @@ class ErrorController extends ActionController
                 $this->view->message = 'Application error';
                 break;
         }
-
         // conditionally display exceptions
         if ($this->getInvokeArg('displayExceptions') == true) {
             $this->view->exception = $errors->exception;

application/views/scripts/error/error.phtml

@@ -11,6 +11,13 @@
 
         <p>
             <b>Message:</b> <?php echo $this->exception->getMessage() ?>
+            <?php if (isset($this->exception->action)): ?>
+                <br/><b>Action</b>: <?= $this->exception->action; ?>
+            <?php endif ?>
+            <?php if (isset($this->exception->action)): ?>
+                <br/><b>Target</b>: <?= $this->exception->target; ?>
+            <?php endif ?>
+      
         </p>
 
         <h3>Stack trace:</h3>

library/Icinga/Exception/SystemPermissionException.php

@@ -0,0 +1,22 @@
+<?php
+// {{{ICINGA_LICENSE_HEADER}}}
+// {{{ICINGA_LICENSE_HEADER}}}
+
+namespace Icinga\Exception;
+
+/**
+ * Class ProgrammingError
+ * @package Icinga\Exception
+ */
+class SystemPermissionException extends \Exception
+{
+    public $action;
+    public $target;
+
+    public function __construct($message, $action, $target = "")
+    {
+        parent::__construct($message);
+        $this->action = $action;
+        $this->target = $target;
+    }
+}