Forbid use of not fully linked classes

Author: nikic

Zend/tests/bug30922.phpt

@@ -10,4 +10,4 @@ var_dump($a instanceOf A);
 echo "ok\n";
 ?>
 --EXPECTF--
-Fatal error: Interface RecurisiveFooFar cannot implement itself in %sbug30922.php on line %d
+Fatal error: Interface 'RecurisiveFooFar' not found in %sbug30922.php on line %d

Zend/tests/use_unlinked_class.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Classes can only be used once they are fully linked
+--FILE--
+<?php
+
+spl_autoload_register(function($class) {
+    echo new ReflectionClass(A::class), "\n";
+});
+
+class A implements I {
+}
+
+?>
+--EXPECTF--
+Fatal error: During class fetch: Uncaught ReflectionException: Class A does not exist in %s:%d
+Stack trace:
+#0 %s(%d): ReflectionClass->__construct('A')
+#1 [internal function]: {closure}('I')
+#2 %s(%d): spl_autoload_call('I')
+#3 {main} in %s on line %d

Zend/zend_compile.h

@@ -269,6 +269,9 @@ typedef struct _zend_oparray_context {
 /* Children must reuse parent get_iterator()              |     |     |     */
 #define ZEND_ACC_REUSE_GET_ITERATOR      (1 << 18) /*  X  |     |     |     */
 /*                                                        |     |     |     */
+/* Class is being linked. Don't free strings.             |     |     |     */
+#define ZEND_ACC_LINKING_IN_PROGRESS     (1 << 19) /*  X  |     |     |     */
+/*                                                        |     |     |     */
 /* Function Flags (unused: 28...30)                       |     |     |     */
 /* ==============                                         |     |     |     */
 /*                                                        |     |     |     */

Zend/zend_execute_API.c

@@ -915,7 +915,11 @@ ZEND_API zend_class_entry *zend_lookup_class_ex(zend_string *name, zend_string *
 		if (!key) {
 			zend_string_release_ex(lc_name, 0);
 		}
-		return (zend_class_entry*)Z_PTR_P(zv);
+		ce = (zend_class_entry*)Z_PTR_P(zv);
+		if (UNEXPECTED(!(ce->ce_flags & ZEND_ACC_LINKED))) {
+			return NULL;
+		}
+		return ce;
 	}
 
 	/* The compiler is not-reentrant. Make sure we __autoload() only during run-time

Zend/zend_inheritance.c

@@ -2091,7 +2091,7 @@ void zend_verify_abstract_class(zend_class_entry *ce) /* {{{ */
 
 ZEND_API void zend_do_link_class(zend_class_entry *ce, zend_class_entry *parent) /* {{{ */
 {
-	ce->ce_flags |= ZEND_ACC_LINKED;
+	ce->ce_flags |= ZEND_ACC_LINKING_IN_PROGRESS;
 	if (parent) {
 		zend_do_inheritance(ce, parent);
 	}
@@ -2106,6 +2106,8 @@ ZEND_API void zend_do_link_class(zend_class_entry *ce, zend_class_entry *parent)
 	}
 
 	zend_build_properties_info_table(ce);
+	ce->ce_flags &= ~ZEND_ACC_LINKING_IN_PROGRESS;
+	ce->ce_flags |= ZEND_ACC_LINKED;
 }
 
 /* Check whether early binding is prevented due to unresolved types in inheritance checks. */

Zend/zend_interfaces.c

@@ -291,7 +291,7 @@ static int zend_implement_traversable(zend_class_entry *interface, zend_class_en
 		return SUCCESS;
 	}
 	if (class_type->num_interfaces) {
-		ZEND_ASSERT(class_type->ce_flags & ZEND_ACC_LINKED);
+		ZEND_ASSERT(class_type->ce_flags & (ZEND_ACC_LINKED|ZEND_ACC_LINKING_IN_PROGRESS));
 		for (i = 0; i < class_type->num_interfaces; i++) {
 			if (class_type->interfaces[i] == zend_ce_aggregate || class_type->interfaces[i] == zend_ce_iterator) {
 				return SUCCESS;
@@ -321,7 +321,7 @@ static int zend_implement_aggregate(zend_class_entry *interface, zend_class_entr
 		} else if (class_type->get_iterator != zend_user_it_get_new_iterator) {
 			/* c-level get_iterator cannot be changed (exception being only Traversable is implemented) */
 			if (class_type->num_interfaces) {
-				ZEND_ASSERT(class_type->ce_flags & ZEND_ACC_LINKED);
+				ZEND_ASSERT(class_type->ce_flags & (ZEND_ACC_LINKED|ZEND_ACC_LINKING_IN_PROGRESS));
 				for (i = 0; i < class_type->num_interfaces; i++) {
 					if (class_type->interfaces[i] == zend_ce_iterator) {
 						zend_error_noreturn(E_ERROR, "Class %s cannot implement both %s and %s at the same time",

Zend/zend_opcode.c

@@ -238,7 +238,7 @@ ZEND_API void destroy_zend_class(zval *zv)
 	}
 	switch (ce->type) {
 		case ZEND_USER_CLASS:
-			if (ce->parent_name && !(ce->ce_flags & ZEND_ACC_LINKED)) {
+			if (ce->parent_name && !(ce->ce_flags & (ZEND_ACC_LINKED|ZEND_ACC_LINKING_IN_PROGRESS))) {
 				zend_string_release_ex(ce->parent_name, 0);
 			}
 			if (ce->default_properties_table) {
@@ -298,7 +298,7 @@ ZEND_API void destroy_zend_class(zval *zv)
 			}
 			zend_hash_destroy(&ce->constants_table);
 			if (ce->num_interfaces > 0) {
-				if (!(ce->ce_flags & ZEND_ACC_LINKED)) {
+				if (!(ce->ce_flags & (ZEND_ACC_LINKED|ZEND_ACC_LINKING_IN_PROGRESS))) {
 					uint32_t i;
 
 					for (i = 0; i < ce->num_interfaces; i++) {