HTML API: Fix detection of single-length funky comments.

Since [60428] the Tag Processor has been misidentifying single-character funky comments. It has been asserting that the full token-length for a funky comment must be at least three characters after the opening (e.g. `</1>`), but it has been starting to look for the closing `>` after those same three characters. This means that it has been skipping the actual close of these funky comments and swallowing up the next syntax until it finds a `>`, often consuming the next tag in the process. This patch fixes the detector and restores finding the following token. Developed in WordPress/wordpress-develop#6412 Discussed in https://core.trac.wordpress.org/ticket/60170 Follow-up to [60428]. Fixes #60170. Props dmsnell, gziolo, jonsurrell. Built from https://develop.svn.wordpress.org/trunk@58040 git-svn-id: http://core.svn.wordpress.org/trunk@57506 1a063a9b-81f0-0310-95a4-ce76da25c4cd
WordPress · Apr 24, 2024 · f9776f5 · f9776f5
1 parent 9d5f848
commit f9776f5
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Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/wp-includes/html-api/class-wp-html-tag-processor.php b/wp-includes/html-api/class-wp-html-tag-processor.php
@@ -1629,7 +1629,7 @@ private function parse_next_tag() {
 			 * `<!` transitions to markup declaration open state
 			 * https://html.spec.whatwg.org/multipage/parsing.html#markup-declaration-open-state
 			 */
-			if ( '!' === $html[ $at + 1 ] ) {
+			if ( ! $this->is_closing_tag && '!' === $html[ $at + 1 ] ) {
 				/*
 				 * `<!--` transitions to a comment state – apply further comment rules.
 				 * https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
@@ -1809,6 +1809,12 @@ private function parse_next_tag() {
 			 * See https://html.spec.whatwg.org/#parse-error-missing-end-tag-name
 			 */
 			if ( '>' === $html[ $at + 1 ] ) {
+				// `<>` is interpreted as plaintext.
+				if ( ! $this->is_closing_tag ) {
+					++$at;
+					continue;
+				}
+
 				$this->parser_state         = self::STATE_PRESUMPTUOUS_TAG;
 				$this->token_length         = $at + 2 - $this->token_starts_at;
 				$this->bytes_already_parsed = $at + 2;
@@ -1819,7 +1825,7 @@ private function parse_next_tag() {
 			 * `<?` transitions to a bogus comment state – skip to the nearest >
 			 * See https://html.spec.whatwg.org/multipage/parsing.html#tag-open-state
 			 */
-			if ( '?' === $html[ $at + 1 ] ) {
+			if ( ! $this->is_closing_tag && '?' === $html[ $at + 1 ] ) {
 				$closer_at = strpos( $html, '>', $at + 2 );
 				if ( false === $closer_at ) {
 					$this->parser_state = self::STATE_INCOMPLETE_INPUT;
@@ -1891,7 +1897,7 @@ private function parse_next_tag() {
 					return false;
 				}
 
-				$closer_at = strpos( $html, '>', $at + 3 );
+				$closer_at = strpos( $html, '>', $at + 2 );
 				if ( false === $closer_at ) {
 					$this->parser_state = self::STATE_INCOMPLETE_INPUT;
 

diff --git a/wp-includes/version.php b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.6-alpha-58039';
+$wp_version = '6.6-alpha-58040';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.