From c8823c71e81f40b51f32e7d5b7821fd985197d99 Mon Sep 17 00:00:00 2001
From: Bernie Reiter <ockham@raz.or.at>
Date: Wed, 22 Feb 2023 16:22:33 +0100
Subject: [PATCH 1/2] Tag Processor: Add Bookmark Invalidation Logic

---
 .../html-api/class-wp-html-tag-processor.php  | 29 ++++++++++++++-----
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/wp-includes/html-api/class-wp-html-tag-processor.php b/src/wp-includes/html-api/class-wp-html-tag-processor.php
index 42675ecd3cf91..eec376f5bcae9 100644
--- a/src/wp-includes/html-api/class-wp-html-tag-processor.php
+++ b/src/wp-includes/html-api/class-wp-html-tag-processor.php
@@ -1401,6 +1401,7 @@ private function class_name_updates_to_attributes_updates() {
 	 * Applies attribute updates to HTML document.
 	 *
 	 * @since 6.2.0
+	 * @since 6.3.0 Invalidate any bookmarks whose targets are overwritten.
 	 *
 	 * @return void
 	 */
@@ -1431,7 +1432,7 @@ private function apply_attributes_updates() {
 		 * Adjust bookmark locations to account for how the text
 		 * replacements adjust offsets in the input document.
 		 */
-		foreach ( $this->bookmarks as $bookmark ) {
+		foreach ( $this->bookmarks as $bookmark_name => $bookmark ) {
 			/*
 			 * Each lexical update which appears before the bookmark's endpoints
 			 * might shift the offsets for those endpoints. Loop through each change
@@ -1442,20 +1443,22 @@ private function apply_attributes_updates() {
 			$tail_delta = 0;
 
 			foreach ( $this->lexical_updates as $diff ) {
-				$update_head = $bookmark->start >= $diff->start;
-				$update_tail = $bookmark->end >= $diff->start;
-
-				if ( ! $update_head && ! $update_tail ) {
+				if ( $bookmark->start < $diff->start && $bookmark->end < $diff->start ) {
 					break;
 				}
 
+				if ( $bookmark->start >= $diff->start && $bookmark->end < $diff->end ) {
+					$this->release_bookmark( $bookmark_name );
+					continue 2;
+				}
+
 				$delta = strlen( $diff->text ) - ( $diff->end - $diff->start );
 
-				if ( $update_head ) {
+				if ( $bookmark->start >= $diff->start ) {
 					$head_delta += $delta;
 				}
 
-				if ( $update_tail ) {
+				if ( $bookmark->end >= $diff->end ) {
 					$tail_delta += $delta;
 				}
 			}
@@ -1467,6 +1470,18 @@ private function apply_attributes_updates() {
 		$this->lexical_updates = array();
 	}
 
+	/**
+	 * Checks whether a bookmark with the given name exists.
+	 *
+	 * @since 6.3.0
+	 *
+	 * @param string $bookmark_name Name to identify a bookmark that potentially exists.
+	 * @return bool Whether that bookmark exists.
+	 */
+	public function has_bookmark( $bookmark_name ) {
+		return array_key_exists( $bookmark_name, $this->bookmarks );
+	}
+
 	/**
 	 * Move the internal cursor in the Tag Processor to a given bookmark's location.
 	 *

From 8f43d6e3a57ed4519e632d89b8a6177a5e21f5b9 Mon Sep 17 00:00:00 2001
From: Bernie Reiter <ockham@raz.or.at>
Date: Wed, 22 Feb 2023 17:51:04 +0100
Subject: [PATCH 2/2] Add unit tests

---
 .../html-api/wpHtmlTagProcessor-bookmark.php  | 35 +++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/tests/phpunit/tests/html-api/wpHtmlTagProcessor-bookmark.php b/tests/phpunit/tests/html-api/wpHtmlTagProcessor-bookmark.php
index 04a6ae590cd7d..caa631dffa698 100644
--- a/tests/phpunit/tests/html-api/wpHtmlTagProcessor-bookmark.php
+++ b/tests/phpunit/tests/html-api/wpHtmlTagProcessor-bookmark.php
@@ -40,6 +40,41 @@ public function test_release_bookmark() {
 		$this->assertTrue( $p->release_bookmark( 'first li' ), 'Could not release a bookmark' );
 	}
 
+	/**
+	 * @ticket 57788
+	 *
+	 * @covers WP_HTML_Tag_Processor::has_bookmark
+	 */
+	public function test_has_bookmark_returns_false_if_bookmark_does_not_exist() {
+		$p = new WP_HTML_Tag_Processor( '<div>Test</div>' );
+		$this->assertFalse( $p->has_bookmark( 'my-bookmark' ) );
+	}
+
+	/**
+	 * @ticket 57788
+	 *
+	 * @covers WP_HTML_Tag_Processor::has_bookmark
+	 */
+	public function test_has_bookmark_returns_true_if_bookmark_exists() {
+		$p = new WP_HTML_Tag_Processor( '<div>Test</div>' );
+		$p->next_tag();
+		$p->set_bookmark( 'my-bookmark' );
+		$this->assertTrue( $p->has_bookmark( 'my-bookmark' ) );
+	}
+
+	/**
+	 * @ticket 57788
+	 *
+	 * @covers WP_HTML_Tag_Processor::has_bookmark
+	 */
+	public function test_has_bookmark_returns_false_if_bookmark_has_been_released() {
+		$p = new WP_HTML_Tag_Processor( '<div>Test</div>' );
+		$p->next_tag();
+		$p->set_bookmark( 'my-bookmark' );
+		$p->release_bookmark( 'my-bookmark' );
+		$this->assertFalse( $p->has_bookmark( 'my-bookmark' ) );
+	}
+
 	/**
 	 * @ticket 56299
 	 *