From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Mon, 1 Feb 2016 13:21:00 +0000 (-0500)
Subject: BT_MOVE(): call bt_put(_dst)
X-Git-Url: http://git.efficios.com/?a=commitdiff_plain;h=f62d1f558a69c03abae7ae054e135e4478655bf9;p=babeltrace.git

BT_MOVE(): call bt_put(_dst)

It makes no semantical sense to move a reference from a variable
to another without first putting the destination, if it has one.
Otherwise this would be a lost reference, unless it was moved
elsewhere or put manually using bt_put() previously, which is why
BT_MOVE() should always be used for move semantics and BT_PUT() is
preferred to bt_put() to avoid this situation.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/include/babeltrace/ref.h b/include/babeltrace/ref.h
index f03f8c9b..68f872cf 100644
--- a/include/babeltrace/ref.h
+++ b/include/babeltrace/ref.h
@@ -53,10 +53,14 @@
  * then sets _src to NULL, effectively moving the ownership of an
  * object from one variable to the other.
  *
+ * Before assigning _src to _dst, it puts _dst. Therefore it is not safe to
+ * call this function with an uninitialized value of _dst.
+ *
  * @param obj Babeltrace object.
  */
 #define BT_MOVE(_dst, _src)	\
 	do {			\
+		bt_put(_dst);	\
 		(_dst) = (_src);\
 		(_src) = NULL;	\
 	} while (0)
diff --git a/tests/lib/test_bt_values.c b/tests/lib/test_bt_values.c
index 34fbc82c..d10ae0cf 100644
--- a/tests/lib/test_bt_values.c
+++ b/tests/lib/test_bt_values.c
@@ -1112,7 +1112,7 @@ void test_macros(void)
 {
 	struct bt_value *obj = bt_value_bool_create();
 	struct bt_value *src;
-	struct bt_value *dst;
+	struct bt_value *dst = NULL;
 
 	assert(obj);
 	BT_PUT(obj);