X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=include%2Furcu%2Fcompiler.h;h=0de713adc1a03f4affc48eda0efd03c1b7c1a470;hb=dd8987a4052e51b87d2a399fec8997c5192f362f;hp=34eb564bb77795e9e77d21983240c3327b3401d1;hpb=087bce43020d2b45dab2dd8ecd6b0d6949c626f3;p=userspace-rcu.git

diff --git a/include/urcu/compiler.h b/include/urcu/compiler.h
index 34eb564..0de713a 100644
--- a/include/urcu/compiler.h
+++ b/include/urcu/compiler.h
@@ -21,6 +21,10 @@
 
 #include <stddef.h>	/* for offsetof */
 
+#if defined __cplusplus
+# include <type_traits>	/* for std::remove_cv */
+#endif
+
 #define caa_likely(x)	__builtin_expect(!!(x), 1)
 #define caa_unlikely(x)	__builtin_expect(!!(x), 0)
 
@@ -70,6 +74,23 @@
 		(type *)((char *)__ptr - offsetof(type, member));	\
 	})
 
+/*
+ * caa_container_of_check_null - Get the address of an object containing a field.
+ *
+ * @ptr: pointer to the field.
+ * @type: type of the object.
+ * @member: name of the field within the object.
+ *
+ * Return the address of the object containing the field. Return NULL if
+ * @ptr is NULL.
+ */
+#define caa_container_of_check_null(ptr, type, member)			\
+	__extension__							\
+	({								\
+		const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \
+		(__ptr) ? (type *)((char *)__ptr - offsetof(type, member)) : NULL; \
+	})
+
 #define CAA_BUILD_BUG_ON_ZERO(cond) (sizeof(struct { int:-!!(cond); }))
 #define CAA_BUILD_BUG_ON(cond) ((void)CAA_BUILD_BUG_ON_ZERO(cond))
 
@@ -82,7 +103,7 @@
 #define __rcu
 
 #ifdef __cplusplus
-#define URCU_FORCE_CAST(type, arg)	(reinterpret_cast<type>(arg))
+#define URCU_FORCE_CAST(_type, arg)	(reinterpret_cast<std::remove_cv<_type>::type>(arg))
 #else
 #define URCU_FORCE_CAST(type, arg)	((type) (arg))
 #endif