XML-RPC: Explicitly unset the reference to the parser resource after calling `xml_parser_free()` to avoid memory leaks in PHP 7.0.0 or higher.

Props procifer, ayeshrajans.
Fixes #49700.
Built from https://develop.svn.wordpress.org/trunk@48322


git-svn-id: http://core.svn.wordpress.org/trunk@48091 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/link-parse-opml.php

@@ -94,3 +94,4 @@ if ( ! xml_parse( $xml_parser, $opml, true ) ) {
 
 // Free up memory used by the XML parser.
 xml_parser_free( $xml_parser );
+unset( $xml_parser );

wp-includes/IXR/class-IXR-message.php

@@ -110,20 +110,28 @@ class IXR_Message
         $chunk_size = apply_filters( 'xmlrpc_chunk_parsing_size', $chunk_size );
 
         $final = false;
+
         do {
             if (strlen($this->message) <= $chunk_size) {
                 $final = true;
             }
+
             $part = substr($this->message, 0, $chunk_size);
             $this->message = substr($this->message, $chunk_size);
+
             if (!xml_parse($this->_parser, $part, $final)) {
+                xml_parser_free($this->_parser);
+                unset($this->_parser);
                 return false;
             }
+
             if ($final) {
                 break;
             }
         } while (true);
+
         xml_parser_free($this->_parser);
+        unset($this->_parser);
 
         // Grab the error messages, if any
         if ($this->messageType == 'fault') {

wp-includes/atomlib.php

@@ -182,6 +182,7 @@ class AtomParser {
         fclose($fp);
 
         xml_parser_free($parser);
+        unset($parser);
 
         restore_error_handler();
 

wp-includes/feed.php

@@ -564,6 +564,7 @@ function prep_atom_text_construct( $data ) {
 	xml_parse( $parser, '<div>' . $data . '</div>', true );
 	$code = xml_get_error_code( $parser );
 	xml_parser_free( $parser );
+	unset( $parser );
 
 	if ( ! $code ) {
 		if ( strpos( $data, '<' ) === false ) {

wp-includes/rss.php

@@ -94,6 +94,7 @@ class MagpieRSS {
 		}
 
 		xml_parser_free( $this->parser );
+		unset( $this->parser );
 
 		$this->normalize();
 	}

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-48321';
+$wp_version = '5.5-alpha-48322';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.