Add flag to forbid dynamic property creation on internal classes

While performing resource -> object migrations, we're adding
defensive classes that are final, non-serializable and non-clonable
(unless they are, of course). This path adds a ZEND_ACC_NO_DYNAMIC_PROPERTIES
flag, that also forbids the creation of dynamic properties on these objects.
This is a subset of #3931 and targeted at internal usage only
(though may be extended to userland at some point in the future).

It's already possible to achieve this (what the removed
WeakRef/WeakMap code does), but there's some caveats: First, this
simple approach is only possible if the class has no declared
properties, otherwise it's necessary to special-case those
properties. Second, it's easy to make it overly strict, e.g. by
forbidding isset($obj->prop) as well. And finally, it requires a
lot of boilerplate code for each class.

Closes GH-5572.

1 files changed, 2 insertions, 45 deletions

diff --git a/Zend/zend_weakrefs.c b/Zend/zend_weakrefs.c
index b633a57e9f..0e94617dbf 100644
--- a/Zend/zend_weakrefs.c
+++ b/Zend/zend_weakrefs.c
@@ -234,39 +234,6 @@ static void zend_weakref_free(zend_object *zo) {
 	zend_object_std_dtor(&wr->std);
 }
 
-#define zend_weakref_unsupported(object, thing) \
-	zend_throw_error(NULL, "%s objects do not support " thing, ZSTR_VAL(object->ce->name));
-
-static ZEND_COLD zval* zend_weakref_no_write(zend_object *object, zend_string *member, zval *value, void **rtc) {
-	zend_weakref_unsupported(object, "properties");
-
-	return &EG(uninitialized_zval);
-}
-
-static ZEND_COLD zval* zend_weakref_no_read(zend_object *object, zend_string *member, int type, void **rtc, zval *rv) {
-	if (!EG(exception)) {
-		zend_weakref_unsupported(object, "properties");
-	}
-
-	return &EG(uninitialized_zval);
-}
-
-static ZEND_COLD zval *zend_weakref_no_read_ptr(zend_object *object, zend_string *member, int type, void **rtc) {
-	zend_weakref_unsupported(object, "property references");
-	return NULL;
-}
-
-static ZEND_COLD int zend_weakref_no_isset(zend_object *object, zend_string *member, int hse, void **rtc) {
-	if (hse != 2) {
-		zend_weakref_unsupported(object, "properties");
-	}
-	return 0;
-}
-
-static ZEND_COLD void zend_weakref_no_unset(zend_object *object, zend_string *member, void **rtc) {
-	zend_weakref_unsupported(object, "properties");
-}
-
 ZEND_COLD ZEND_METHOD(WeakReference, __construct)
 {
 	zend_throw_error(NULL,
@@ -615,7 +582,7 @@ void zend_register_weakref_ce(void) /* {{{ */
 
 	INIT_CLASS_ENTRY(ce, "WeakReference", class_WeakReference_methods);
 	zend_ce_weakref = zend_register_internal_class(&ce);
-	zend_ce_weakref->ce_flags |= ZEND_ACC_FINAL;
+	zend_ce_weakref->ce_flags |= ZEND_ACC_FINAL | ZEND_ACC_NO_DYNAMIC_PROPERTIES;
 
 	zend_ce_weakref->create_object = zend_weakref_new;
 	zend_ce_weakref->serialize = zend_class_serialize_deny;
@@ -625,16 +592,11 @@ void zend_register_weakref_ce(void) /* {{{ */
 	zend_weakref_handlers.offset = XtOffsetOf(zend_weakref, std);
 
 	zend_weakref_handlers.free_obj = zend_weakref_free;
-	zend_weakref_handlers.read_property = zend_weakref_no_read;
-	zend_weakref_handlers.write_property = zend_weakref_no_write;
-	zend_weakref_handlers.has_property = zend_weakref_no_isset;
-	zend_weakref_handlers.unset_property = zend_weakref_no_unset;
-	zend_weakref_handlers.get_property_ptr_ptr = zend_weakref_no_read_ptr;
 	zend_weakref_handlers.clone_obj = NULL;
 
 	INIT_CLASS_ENTRY(ce, "WeakMap", class_WeakMap_methods);
 	zend_ce_weakmap = zend_register_internal_class(&ce);
-	zend_ce_weakmap->ce_flags |= ZEND_ACC_FINAL;
+	zend_ce_weakmap->ce_flags |= ZEND_ACC_FINAL | ZEND_ACC_NO_DYNAMIC_PROPERTIES;
 
 	zend_ce_weakmap->create_object = zend_weakmap_create_object;
 	zend_ce_weakmap->get_iterator = zend_weakmap_get_iterator;
@@ -656,11 +618,6 @@ void zend_register_weakref_ce(void) /* {{{ */
 	zend_weakmap_handlers.get_properties_for = zend_weakmap_get_properties_for;
 	zend_weakmap_handlers.get_gc = zend_weakmap_get_gc;
 	zend_weakmap_handlers.clone_obj = zend_weakmap_clone_obj;
-	zend_weakmap_handlers.read_property = zend_weakref_no_read;
-	zend_weakmap_handlers.write_property = zend_weakref_no_write;
-	zend_weakmap_handlers.has_property = zend_weakref_no_isset;
-	zend_weakmap_handlers.unset_property = zend_weakref_no_unset;
-	zend_weakmap_handlers.get_property_ptr_ptr = zend_weakref_no_read_ptr;
 }
 /* }}} */