server: add a basic container_of macro

Add a basic container_of macro to list.h. This is primarily for systems
in which container_of has no definition.

Signed-off-by: Danny Holman <dholman@gymli.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/server/include/list.h b/server/include/list.h
index fc3af68..b75e846 100644
--- a/server/include/list.h
+++ b/server/include/list.h
@@ -3,6 +3,12 @@
 
 #include <stddef.h>
 
+#ifndef container_of
+#define container_of(ptr, type, member) ({                              \
+                const typeof(((type*)0)->member)*__mptr = (ptr);        \
+                (type*)((char*)__mptr - offsetof(type, member)); })
+#endif
+
 struct list_head {
         struct list_head *next;
         struct list_head *prev;