1 files changed, 11 insertions, 0 deletions
diff --git a/src/config.h b/src/config.h
index 34ae11d..cee8511 100644
--- a/src/config.h
+++ b/src/config.h
@@ -147,6 +147,17 @@
  */
 #define BFS_COUNTOF(array) (sizeof(array) / sizeof(0[array]))
 
+// BFS_CONTAINER_OF() helper
+static inline char *bfs_container_offset(char *ptr, ptrdiff_t offset, size_t unused) {
+	return ptr ? ptr - offset : NULL;
+}
+
+/**
+ * Move a pointer from a field to its outer struct.
+ */
+#define BFS_CONTAINER_OF(ptr, type, member) \
+	((type *)bfs_container_offset((char *)(ptr), offsetof(type, member), sizeof((ptr) - &((type *)NULL)->member)))
+
 // Lower bound on BFS_FLEX_SIZEOF()
 #define BFS_FLEX_LB(type, member, length) (offsetof(type, member) + sizeof(((type *)NULL)->member[0]) * (length))