Avoid unnecessary string refcounting in ext/dom (#17889)

Author: nielsdos

ext/dom/document.c

@@ -194,13 +194,12 @@ zend_result dom_document_version_write(dom_object *obj, zval *newval)
 {
 	DOM_PROP_NODE(xmlDocPtr, docp, obj);
 
-	/* Cannot fail because the type is either null or a string. */
-	zend_string *str = zval_get_string(newval);
+	/* Type is ?string */
+	zend_string *str = Z_TYPE_P(newval) == IS_NULL ? ZSTR_EMPTY_ALLOC() : Z_STR_P(newval);
 
 	if (php_dom_follow_spec_intern(obj)) {
 		if (!zend_string_equals_literal(str, "1.0") && !zend_string_equals_literal(str, "1.1")) {
 			zend_value_error("Invalid XML version");
-			zend_string_release_ex(str, 0);
 			return FAILURE;
 		}
 	}
@@ -211,7 +210,6 @@ zend_result dom_document_version_write(dom_object *obj, zval *newval)
 
 	docp->version = xmlStrdup((const xmlChar *) ZSTR_VAL(str));
 
-	zend_string_release_ex(str, 0);
 	return SUCCESS;
 }
 
@@ -394,16 +392,15 @@ zend_result dom_document_document_uri_write(dom_object *obj, zval *newval)
 {
 	DOM_PROP_NODE(xmlDocPtr, docp, obj);
 
-	/* Cannot fail because the type is either null or a string. */
-	zend_string *str = zval_get_string(newval);
+	/* Type is ?string */
+	zend_string *str = Z_TYPE_P(newval) == IS_NULL ? ZSTR_EMPTY_ALLOC() : Z_STR_P(newval);
 
 	if (docp->URL != NULL) {
 		xmlFree(BAD_CAST docp->URL);
 	}
 
 	docp->URL = xmlStrdup((const xmlChar *) ZSTR_VAL(str));
 
-	zend_string_release_ex(str, 0);
 	return SUCCESS;
 }
 

ext/dom/node.c

@@ -185,8 +185,8 @@ zend_result dom_node_node_value_write(dom_object *obj, zval *newval)
 {
 	DOM_PROP_NODE(xmlNodePtr, nodep, obj);
 
-	/* Cannot fail because the type is either null or a string. */
-	zend_string *str = zval_get_string(newval);
+	/* Type is ?string */
+	zend_string *str = Z_TYPE_P(newval) == IS_NULL ? ZSTR_EMPTY_ALLOC() : Z_STR_P(newval);
 
 	/* Access to Element node is implemented as a convenience method */
 	switch (nodep->type) {
@@ -213,7 +213,6 @@ zend_result dom_node_node_value_write(dom_object *obj, zval *newval)
 
 	php_libxml_invalidate_node_list_cache(obj->document);
 
-	zend_string_release_ex(str, 0);
 	return SUCCESS;
 }
 

ext/dom/xpath_callbacks.c

@@ -206,13 +206,14 @@ static zend_result php_dom_xpath_callback_ns_update_method_handler(
 			ZVAL_PTR(&registered_value, fcc);
 
 			if (!key) {
-				zend_string *str = zval_try_get_string(entry);
+				zend_string *tmp_str;
+				zend_string *str = zval_try_get_tmp_string(entry, &tmp_str);
 				if (str && php_dom_xpath_is_callback_name_valid_and_throw(str, name_validation, true)) {
 					zend_hash_update(&ns->functions, str, &registered_value);
 					if (register_func) {
 						register_func(ctxt, namespace, str);
 					}
-					zend_string_release_ex(str, false);
+					zend_tmp_string_release(tmp_str);
 				} else {
 					zend_fcc_dtor(fcc);
 					efree(fcc);
@@ -445,9 +446,10 @@ static zend_result php_dom_xpath_callback_dispatch(php_dom_xpath_callbacks *xpat
 			zval_ptr_dtor(&callback_retval);
 			return FAILURE;
 		} else {
-			zend_string *str = zval_get_string(&callback_retval);
+			zend_string *tmp_str;
+			zend_string *str = zval_get_tmp_string(&callback_retval, &tmp_str);
 			valuePush(ctxt, xmlXPathNewString(BAD_CAST ZSTR_VAL(str)));
-			zend_string_release_ex(str, 0);
+			zend_tmp_string_release(tmp_str);
 		}
 		zval_ptr_dtor(&callback_retval);
 	}