From 8cdd96f286c589e808f45f09f716c578c3ba2299 Mon Sep 17 00:00:00 2001
From: Isaac Connor <isaac@zoneminder.com>
Date: Tue, 8 Feb 2022 13:29:51 -0500
Subject: [PATCH] Implement a check on change of language.  Make sure that the
 specified language file exists. Reports errors to UI

---
 web/includes/actions/options.php | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/web/includes/actions/options.php b/web/includes/actions/options.php
index 07b71c001..9b0033f4e 100644
--- a/web/includes/actions/options.php
+++ b/web/includes/actions/options.php
@@ -24,6 +24,8 @@ if ( !canEdit('System') ) {
   return;
 }
 
+global $error_message;
+
 if ( $action == 'delete' ) {
   if ( isset($_REQUEST['object']) ) {
     if ( $_REQUEST['object'] == 'server' ) {
@@ -65,10 +67,19 @@ if ( $action == 'delete' ) {
     }
 
     if ( isset($newValue) && ($newValue != $config['Value']) ) {
+      # Handle special cases first
+      if ($config['Name'] == 'ZM_LANG_DEFAULT') {
+        # Verify that the language file exists in the lang directory.
+        if (!file_exists(ZM_PATH_WEB.'/lang/'.$newValue.'.php')) {
+          $error_message .= 'Error setting ' . $config['Name'].'. New value ' .$newValue.' not saved because '.ZM_PATH_WEB.'/lang/'.$newValue.'.php doesn\'t exist.<br/>';
+          ZM\Error($error_message);
+          continue;
+        }
+      }
       dbQuery('UPDATE Config SET Value=? WHERE Name=?', array($newValue, $config['Name']));
       $changed = true;
-    }
-  }
+    } # end if value changed
+  } # end foreach config entry
   if ( $changed ) {
     switch ( $_REQUEST['tab'] ) {
     case 'system' :