object.c: fix memory leak

* object.c (rb_obj_copy_ivar): allocate no memory for empty
  instance variables.  [ruby-core:64700] [Bug #10191]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47372 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Sep  3 16:56:07 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* object.c (rb_obj_copy_ivar): allocate no memory for empty
+	  instance variables.  [ruby-core:64700] [Bug #10191]
+
 Wed Sep  3 12:05:17 2014  Tanaka Akira  <akr@fsij.org>
 
 	* process.c (retry_fork_async_signal_safe): Use vfork() if available.

object.c

@@ -270,8 +270,11 @@ rb_obj_copy_ivar(VALUE dest, VALUE obj)
     }
     else {
 	long len = ROBJECT(obj)->as.heap.numiv;
-	VALUE *ptr = ALLOC_N(VALUE, len);
+	VALUE *ptr = 0;
-	MEMCPY(ptr, ROBJECT(obj)->as.heap.ivptr, VALUE, len);
+	if (len > 0) {
+	    ptr = ALLOC_N(VALUE, len);
+	    MEMCPY(ptr, ROBJECT(obj)->as.heap.ivptr, VALUE, len);
+	}
 	ROBJECT(dest)->as.heap.ivptr = ptr;
 	ROBJECT(dest)->as.heap.numiv = len;
 	ROBJECT(dest)->as.heap.iv_index_tbl = ROBJECT(obj)->as.heap.iv_index_tbl;

test/ruby/test_object.rb

@@ -811,4 +811,14 @@ class TestObject < Test::Unit::TestCase
     assert_raise_with_message(TypeError, "can't convert Array into Integer") {Integer([42])}
     assert_raise_with_message(TypeError, 'no implicit conversion of Array into Integer') {[].first([42])}
   end
+
+  def test_copied_ivar_memory_leak
+    bug10191 = '[ruby-core:64700] [Bug #10191]'
+    assert_no_memory_leak([], <<-"end;", <<-"end;", bug10191, rss: true)
+      def (a = Object.new).set; @v = nil; end
+      num = 500_000
+    end;
+      num.times {a.clone.set}
+    end;
+  end
 end