Avoid code duplication in PR #2891

app/functions.php

@@ -145,6 +145,17 @@ function get_upload_max_size()
     return min(ini_get('upload_max_filesize'), ini_get('post_max_size'));
 }
 
+/**
+ * Get file extension
+ *
+ * @param  $filename
+ * @return string
+ */
+function get_file_extension($filename)
+{
+    return strtolower(pathinfo($filename, PATHINFO_EXTENSION));
+}
+
 /**
  * Translate a string
  *