From: ko1@...
Date: 2015-12-16T08:06:19+00:00
Subject: [ruby-core:72180] [Ruby trunk - Bug #11740] ObjectSpace.each_object exposes internal metaclasses

Issue #11740 has been updated by Koichi Sasada.


```diff
Index: class.c
===================================================================
--- class.c	(revision 53150)
+++ class.c	(working copy)
@@ -442,6 +442,12 @@ rb_singleton_class_attached(VALUE klass,
  */
 #define META_CLASS_OF_CLASS_CLASS_P(k)  (METACLASS_OF(k) == (k))
 
+int
+rb_singleton_class_has_metaclass_p(VALUE sklass)
+{
+    return rb_ivar_get(METACLASS_OF(sklass), id_attached) == sklass;
+}
+
 /*!
  * whether k has a metaclass
  * @retval 1 if \a k has a metaclass
@@ -449,7 +455,13 @@ rb_singleton_class_attached(VALUE klass,
  */
 #define HAVE_METACLASS_P(k) \
     (FL_TEST(METACLASS_OF(k), FL_SINGLETON) && \
-     rb_ivar_get(METACLASS_OF(k), id_attached) == (k))
+     rb_singleton_class_has_metaclass_p(k))
+
+int
+rb_class_has_metaclass_p(VALUE klass)
+{
+    return HAVE_METACLASS_P(klass);
+}
 
 /*!
  * ensures \a klass belongs to its own eigenclass.
Index: gc.c
===================================================================
--- gc.c	(revision 53150)
+++ gc.c	(working copy)
@@ -2400,6 +2400,13 @@ internal_object_p(VALUE obj)
 	  case T_NODE:
 	  case T_ZOMBIE:
 	    break;
+	  case T_CLASS:
+	    {
+		if (FL_TEST(obj, FL_SINGLETON)) {
+		    int rb_singleton_class_has_metaclass_p(VALUE sklass);
+		    return rb_singleton_class_has_metaclass_p(obj) == 0;
+		}
+	    }
 	  default:
 	    if (!p->as.basic.klass) break;
 	    return 0;
```

This patch solves this problem.
Could you check it?


----------------------------------------
Bug #11740: ObjectSpace.each_object exposes internal metaclasses
https://bugs.ruby-lang.org/issues/11740#change-55594

* Author: Benoit Daloze
* Status: Open
* Priority: Normal
* Assignee: Koichi Sasada
* ruby -v: ruby 2.3.0dev (2015-11-19 trunk 52672) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
ObjectSpace.each_object exposes internal metaclasses and
this might result in assumptions being violated since the metaclass structure is not well preserved.

See the attached script for an example.
The #bla method should always be defined on the metaclass of "klass".

See https://bugs.ruby-lang.org/issues/11360#note-2 as well in which I warned against this problem ;)

---Files--------------------------------
objspace_expose_intern_meta.rb (413 Bytes)


-- 
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