From e42eeb62b05b2fa48e56d922bfdad2840a8c3678 Mon Sep 17 00:00:00 2001
From: Petr Skoda <commits@skodak.org>
Date: Thu, 14 Sep 2023 18:44:18 +0200
Subject: [PATCH] MDL-79360 filter: fix nolink tag regression from MDL-77525

---
 lib/filterlib.php                     |  6 +++--
 lib/tests/weblib_format_text_test.php | 38 +++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/lib/filterlib.php b/lib/filterlib.php
index 58aeaff6d2a06..efdf68f8036b8 100644
--- a/lib/filterlib.php
+++ b/lib/filterlib.php
@@ -228,8 +228,10 @@ protected function get_string_filters($context) {
     public function filter_text($text, $context, array $options = array(),
             array $skipfilters = null) {
         $text = $this->apply_filter_chain($text, $this->get_text_filters($context), $options, $skipfilters);
-        // Remove <nolink> tags for XHTML compatibility.
-        $text = str_replace(array('<nolink>', '</nolink>'), '', $text);
+        if (!isset($options['stage']) || $options['stage'] === 'post_clean') {
+            // Remove <nolink> tags for XHTML compatibility after the last filtering stage.
+            $text = str_replace(array('<nolink>', '</nolink>'), '', $text);
+        }
         return $text;
     }
 
diff --git a/lib/tests/weblib_format_text_test.php b/lib/tests/weblib_format_text_test.php
index 6aab808bedcda..3593dcf20bacc 100644
--- a/lib/tests/weblib_format_text_test.php
+++ b/lib/tests/weblib_format_text_test.php
@@ -19,6 +19,8 @@
 /**
  * Unit tests for format_text defined in weblib.php.
  *
+ * @covers ::format_text
+ *
  * @package   core
  * @category  test
  * @copyright 2015 The Open University
@@ -88,6 +90,42 @@ public function test_format_text_format_moodle_no_filters() {
                 format_text('<p>:-)</p>', FORMAT_MOODLE, array('filter' => false)));
     }
 
+    /**
+     * Make sure that nolink tags and spans prevent linking in filters that support it.
+     */
+    public function test_format_text_nolink() {
+        global $CFG;
+        $this->resetAfterTest();
+        filter_set_global_state('activitynames', TEXTFILTER_ON);
+
+        $course = $this->getDataGenerator()->create_course();
+        $context = \context_course::instance($course->id);
+        $page = $this->getDataGenerator()->create_module('page',
+            ['course' => $course->id, 'name' => 'Test 1']);
+        $cm = get_coursemodule_from_instance('page', $page->id, $page->course, false, MUST_EXIST);
+        $pageurl = $CFG->wwwroot. '/mod/page/view.php?id=' . $cm->id;
+
+        $this->assertSame(
+            '<p>Read <a class="autolink" title="Test 1" href="' . $pageurl . '">Test 1</a>.</p>',
+            format_text('<p>Read Test 1.</p>', FORMAT_HTML, ['context' => $context]));
+
+        $this->assertSame(
+            '<p>Read <a class="autolink" title="Test 1" href="' . $pageurl . '">Test 1</a>.</p>',
+            format_text('<p>Read Test 1.</p>', FORMAT_HTML, ['context' => $context, 'noclean' => true]));
+
+        $this->assertSame(
+            '<p>Read Test 1.</p>',
+            format_text('<p><nolink>Read Test 1.</nolink></p>', FORMAT_HTML, ['context' => $context, 'noclean' => false]));
+
+        $this->assertSame(
+            '<p>Read Test 1.</p>',
+            format_text('<p><nolink>Read Test 1.</nolink></p>', FORMAT_HTML, ['context' => $context, 'noclean' => true]));
+
+        $this->assertSame(
+            '<p><span class="nolink">Read Test 1.</span></p>',
+            format_text('<p><span class="nolink">Read Test 1.</span></p>', FORMAT_HTML, ['context' => $context]));
+    }
+
     public function test_format_text_overflowdiv() {
         $this->assertEquals('<div class="no-overflow"><p>Hello world</p></div>',
                 format_text('<p>Hello world</p>', FORMAT_HTML, array('overflowdiv' => true)));