From e464bf3c7d875d7cd95c3a04d74f513e209a3edc Mon Sep 17 00:00:00 2001
From: Lior Gil <liorgil.lg@gmail.com>
Date: Sun, 2 Jul 2023 09:05:27 +0300
Subject: [PATCH] MDL-76203 weblib: Add BDI support to the HTML purifier

---
 lib/weblib.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/weblib.php b/lib/weblib.php
index 29041dffb03..76cb3e92ac0 100644
--- a/lib/weblib.php
+++ b/lib/weblib.php
@@ -1927,6 +1927,9 @@ function purify_html($text, $options = array()) {
             $def->addElement('algebra', 'Inline', 'Inline', array());                   // Algebra syntax, equivalent to @@xx@@.
             $def->addElement('lang', 'Block', 'Flow', array(), array('lang'=>'CDATA')); // Original multilang style - only our hacked lang attribute.
             $def->addAttribute('span', 'xxxlang', 'CDATA');                             // Current very problematic multilang.
+            // Enable the bidirectional isolate element and its span equivalent.
+            $def->addElement('bdi', 'Inline', 'Flow', 'Common');
+            $def->addAttribute('span', 'dir', 'Enum#ltr,rtl,auto');
 
             // Media elements.
             // https://html.spec.whatwg.org/#the-video-element