brlib repo creation

include/container-of.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* adaptation of Linux kernel's <linux/container_of.h>
+ */
+#ifndef _BR_CONTAINER_OF_H
+#define _BR_CONTAINER_OF_H
+
+/* Are two types/vars the same type (ignoring qualifiers)? */
+#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
+
+/**
+ * typeof_member -
+ */
+#define typeof_member(T, m)     typeof(((T*)0)->m)
+
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr:        the pointer to the member.
+ * @type:       the type of the container struct this is embedded in.
+ * @member:     the name of the member within the struct.
+ *
+ */
+#define container_of(ptr, type, member) ({                              \
+        void *__mptr = (void *)(ptr);                                   \
+        _Static_assert(__same_type(*(ptr), ((type *)0)->member) ||       \
+                      __same_type(*(ptr), void),                        \
+                      "pointer type mismatch in container_of()");       \
+        ((type *)(__mptr - offsetof(type, member))); })
+
+#endif /* BR_CONTAINER_OF_H */