Enforce namespace-scoped visibility for property access

Add runtime checks for private(namespace) properties, supporting both
regular and asymmetric visibility:

* Read access: Check ZEND_ACC_NAMESPACE_PRIVATE flag
* Write access: Check ZEND_ACC_NAMESPACE_PRIVATE_SET flag via
  zend_asymmetric_property_has_set_access()

This applies to:
* Instance properties (zend_get_property_offset, zend_get_property_info)
* Static properties (zend_std_get_static_property_with_info)
* Asymmetric visibility (zend_asymmetric_property_has_set_access)

Supports asymmetric visibility patterns like:
  public private(namespace)(set) int $count;
Where the property is publicly readable but only writable within
the namespace.

All checks compare the property's class namespace with the caller's
namespace using zend_get_class_namespace() and zend_get_caller_namespace(),
denying access when namespaces don't match.

Author: withinboredom

Zend/zend_object_handlers.c

@@ -391,7 +391,7 @@ static zend_always_inline uintptr_t zend_get_property_offset(zend_class_entry *c
 	property_info = (zend_property_info*)Z_PTR_P(zv);
 	flags = property_info->flags;
 
-	if (flags & (ZEND_ACC_CHANGED|ZEND_ACC_PRIVATE|ZEND_ACC_PROTECTED)) {
+	if (flags & (ZEND_ACC_CHANGED|ZEND_ACC_PRIVATE|ZEND_ACC_PROTECTED|ZEND_ACC_NAMESPACE_PRIVATE)) {
 		const zend_class_entry *scope = get_fake_or_executed_scope();
 
 		if (property_info->ce != scope) {
@@ -421,6 +421,14 @@ static zend_always_inline uintptr_t zend_get_property_offset(zend_class_entry *c
 					}
 					return ZEND_WRONG_PROPERTY_OFFSET;
 				}
+			} else if (flags & ZEND_ACC_NAMESPACE_PRIVATE) {
+				/* Check namespace visibility */
+				zend_string *property_namespace = zend_get_class_namespace(property_info->ce);
+				zend_string *caller_namespace = zend_get_caller_namespace();
+
+				if (!zend_string_equals(property_namespace, caller_namespace)) {
+					goto wrong;
+				}
 			} else {
 				ZEND_ASSERT(flags & ZEND_ACC_PROTECTED);
 				if (UNEXPECTED(!is_protected_compatible_scope(property_info->prototype->ce, scope))) {
@@ -491,7 +499,7 @@ ZEND_API zend_property_info *zend_get_property_info(const zend_class_entry *ce,
 	property_info = (zend_property_info*)Z_PTR_P(zv);
 	flags = property_info->flags;
 
-	if (flags & (ZEND_ACC_CHANGED|ZEND_ACC_PRIVATE|ZEND_ACC_PROTECTED)) {
+	if (flags & (ZEND_ACC_CHANGED|ZEND_ACC_PRIVATE|ZEND_ACC_PROTECTED|ZEND_ACC_NAMESPACE_PRIVATE)) {
 		const zend_class_entry *scope = get_fake_or_executed_scope();
 		if (property_info->ce != scope) {
 			if (flags & ZEND_ACC_CHANGED) {
@@ -516,6 +524,14 @@ ZEND_API zend_property_info *zend_get_property_info(const zend_class_entry *ce,
 					}
 					return ZEND_WRONG_PROPERTY_INFO;
 				}
+			} else if (flags & ZEND_ACC_NAMESPACE_PRIVATE) {
+				/* Check namespace visibility */
+				zend_string *property_namespace = zend_get_class_namespace(property_info->ce);
+				zend_string *caller_namespace = zend_get_caller_namespace();
+
+				if (!zend_string_equals(property_namespace, caller_namespace)) {
+					goto wrong;
+				}
 			} else {
 				ZEND_ASSERT(flags & ZEND_ACC_PROTECTED);
 				if (UNEXPECTED(!is_protected_compatible_scope(property_info->prototype->ce, scope))) {
@@ -593,6 +609,18 @@ ZEND_API bool ZEND_FASTCALL zend_asymmetric_property_has_set_access(const zend_p
 	if (prop_info->ce == scope) {
 		return true;
 	}
+
+	/* Check namespace_private(set) visibility */
+	if (prop_info->flags & ZEND_ACC_NAMESPACE_PRIVATE_SET) {
+		zend_string *property_namespace = zend_get_class_namespace(prop_info->ce);
+		zend_string *caller_namespace = zend_get_caller_namespace();
+
+		if (zend_string_equals(property_namespace, caller_namespace)) {
+			return true;
+		}
+		return false;
+	}
+
 	return EXPECTED((prop_info->flags & ZEND_ACC_PROTECTED_SET)
 		&& is_protected_compatible_scope(prop_info->prototype->ce, scope));
 }
@@ -2061,6 +2089,19 @@ ZEND_API zval *zend_std_get_static_property_with_info(zend_class_entry *ce, zend
 				return NULL;
 			}
 		}
+
+		/* Check namespace visibility */
+		if (UNEXPECTED(property_info->flags & ZEND_ACC_NAMESPACE_PRIVATE)) {
+			zend_string *property_namespace = zend_get_class_namespace(property_info->ce);
+			zend_string *caller_namespace = zend_get_caller_namespace();
+
+			if (!zend_string_equals(property_namespace, caller_namespace)) {
+				if (type != BP_VAR_IS) {
+					zend_bad_property_access(property_info, ce, property_name);
+				}
+				return NULL;
+			}
+		}
 	}
 
 	if (UNEXPECTED((property_info->flags & ZEND_ACC_STATIC) == 0)) {