Redirect loop when site is offline and home page sends a 404 (solves

joomla#7670)

language/en-GB/en-GB.ini

@@ -205,6 +205,7 @@ JGLOBAL_LT="<"
 JGLOBAL_NEWITEMSLAST_DESC="New items default to the last position. Ordering can be changed after this item has been saved."
 JGLOBAL_NO_MATCHING_RESULTS="No Matching Results"
 JGLOBAL_NUM="#"
+JGLOBAL_OFFLINE_ERROR="This site is offline and the Home Page sends a 404 error. Please contact a site administrator."
 JGLOBAL_OTPMETHOD_NONE="Disable Two Factor Authentication"
 JGLOBAL_PASSWORD="Password"
 JGLOBAL_PASSWORD_RESET_REQUIRED="You are required to reset your password before proceeding."

libraries/legacy/error/error.php

@@ -786,11 +786,21 @@ public static function customErrorPage(&$error)
 
 			// Push the error object into the document
 			$document->setError($error);
+			$homemenu	= $app->getMenu()->getDefault(JFactory::getLanguage()->getTag());
+			$active		= $app->getMenu()->getActive();
 
 			// If site is offline and it's a 404 error, just go to index (to see offline message, instead of 404)
+			// If the 404 concerns the home page, exit and display a message
 			if ($error->getCode() == '404' && JFactory::getConfig()->get('offline') == 1)
 			{
-				JFactory::getApplication()->redirect('index.php');
+				if ($homemenu !== $active)
+				{
+					JFactory::getApplication()->redirect('index.php');
+				}
+				else
+				{
+					jexit(JText::_('JGLOBAL_OFFLINE_ERROR'));
+				}
 			}
 
 			@ob_end_clean();