Allow writing to readonly properties during cloning

Author: nicolas-grekas

Zend/tests/readonly_props/readonly_clone.phpt

@@ -0,0 +1,66 @@
+--TEST--
+clone can write to readonly properties
+--FILE--
+<?php
+
+class Counter
+{
+    private static int $counter = 0;
+
+    public readonly int $count;
+    private readonly int $foo;
+
+    public function __construct()
+    {
+        $this->count = ++self::$counter;
+        $this->foo = 0;
+    }
+
+    public function count(?int $count = null): static
+    {
+        $new = clone $this;
+        $new->count = $count ?? ++self::$counter;
+
+        return $new;
+    }
+
+    public function __clone()
+    {
+        if (is_a(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 2)[1]['class'] ?? '', self::class, true)) {
+            unset($this->count);
+        } else {
+            $this->count = ++self::$counter;
+        }
+        $this->foo = 1;
+    }
+}
+
+$a = new Counter();
+var_dump($a);
+
+var_dump(clone $a);
+
+$b = $a->count();
+var_dump($b);
+
+$c = $a->count(123);
+var_dump($c);
+
+?>
+--EXPECT--
+object(Counter)#1 (1) {
+  ["count"]=>
+  int(1)
+}
+object(Counter)#2 (1) {
+  ["count"]=>
+  int(2)
+}
+object(Counter)#2 (1) {
+  ["count"]=>
+  int(3)
+}
+object(Counter)#3 (1) {
+  ["count"]=>
+  int(123)
+}

Zend/zend_object_handlers.c

@@ -811,7 +811,7 @@ ZEND_API zval *zend_std_write_property(zend_object *zobj, zend_string *name, zva
 			Z_TRY_ADDREF_P(value);
 
 			if (UNEXPECTED(prop_info)) {
-				if (UNEXPECTED(prop_info->flags & ZEND_ACC_READONLY)) {
+				if (UNEXPECTED((prop_info->flags & ZEND_ACC_READONLY) && Z_PROP_FLAG_P(variable_ptr) != IS_PROP_UNINIT)) {
 					Z_TRY_DELREF_P(value);
 					zend_readonly_property_modification_error(prop_info);
 					variable_ptr = &EG(error_zval);
@@ -1126,7 +1126,7 @@ ZEND_API void zend_std_unset_property(zend_object *zobj, zend_string *name, void
 		zval *slot = OBJ_PROP(zobj, property_offset);
 
 		if (Z_TYPE_P(slot) != IS_UNDEF) {
-			if (UNEXPECTED(prop_info && (prop_info->flags & ZEND_ACC_READONLY))) {
+			if (UNEXPECTED(prop_info && (prop_info->flags & ZEND_ACC_READONLY) && Z_PROP_FLAG_P(slot) != IS_PROP_UNINIT)) {
 				zend_readonly_property_unset_error(prop_info->ce, name);
 				return;
 			}

Zend/zend_objects.c

@@ -192,21 +192,30 @@ ZEND_API zend_object* ZEND_FASTCALL zend_objects_new(zend_class_entry *ce)
 
 ZEND_API void ZEND_FASTCALL zend_objects_clone_members(zend_object *new_object, zend_object *old_object)
 {
+	zval *src, *dst, *end, *slot;
+	zend_property_info *prop_info;
+
 	if (old_object->ce->default_properties_count) {
-		zval *src = old_object->properties_table;
-		zval *dst = new_object->properties_table;
-		zval *end = src + old_object->ce->default_properties_count;
+		src = old_object->properties_table;
+		dst = new_object->properties_table;
+		end = src + old_object->ce->default_properties_count;
 
 		do {
 			i_zval_ptr_dtor(dst);
 			ZVAL_COPY_VALUE_PROP(dst, src);
 			zval_add_ref(dst);
 			if (UNEXPECTED(Z_ISREF_P(dst)) &&
 					(ZEND_DEBUG || ZEND_REF_HAS_TYPE_SOURCES(Z_REF_P(dst)))) {
-				zend_property_info *prop_info = zend_get_property_info_for_slot(new_object, dst);
+				prop_info = zend_get_property_info_for_slot(new_object, dst);
 				if (ZEND_TYPE_IS_SET(prop_info->type)) {
 					ZEND_REF_ADD_TYPE_SOURCE(Z_REF_P(dst), prop_info);
 				}
+			} else if (UNEXPECTED(old_object->ce->clone)) {
+				prop_info = zend_get_property_info_for_slot(new_object, dst);
+				if (UNEXPECTED(prop_info->flags & ZEND_ACC_READONLY)) {
+					slot = OBJ_PROP(new_object, prop_info->offset);
+					Z_PROP_FLAG_P(slot) = IS_PROP_UNINIT;
+				}
 			}
 			src++;
 			dst++;
@@ -256,6 +265,20 @@ ZEND_API void ZEND_FASTCALL zend_objects_clone_members(zend_object *new_object,
 	if (old_object->ce->clone) {
 		GC_ADDREF(new_object);
 		zend_call_known_instance_method_with_0_params(new_object->ce->clone, new_object, NULL);
+		if (new_object->ce->default_properties_count) {
+			dst = new_object->properties_table;
+			end = dst + new_object->ce->default_properties_count;
+			do {
+				prop_info = zend_get_property_info_for_slot(new_object, dst);
+				if (UNEXPECTED(prop_info->flags & ZEND_ACC_READONLY)) {
+					slot = OBJ_PROP(new_object, prop_info->offset);
+					if (Z_TYPE_P(slot) != IS_UNDEF && Z_PROP_FLAG_P(slot) == IS_PROP_UNINIT) {
+						Z_PROP_FLAG_P(slot) = 0;
+					}
+				}
+				dst++;
+			} while (dst != end);
+		}
 		OBJ_RELEASE(new_object);
 	}
 }