From: Petri Lehtinen <petri@digip.org>
Date: Thu, 12 Aug 2010 18:34:02 +0000 (+0300)
Subject: Beautify the container_of macro
X-Git-Tag: v2.0~43^2~2
X-Git-Url: http://www.project-moonshot.org/gitweb/?p=jansson.git;a=commitdiff_plain;h=519d52e2bb6a3840100a84e826d8d8ac91e2d3d8

Beautify the container_of macro

Use offsetof instead of zero pointer dereference trickery.
---

diff --git a/src/jansson_private.h b/src/jansson_private.h
index 4490702..6d7e46c 100644
--- a/src/jansson_private.h
+++ b/src/jansson_private.h
@@ -8,11 +8,12 @@
 #ifndef JANSSON_PRIVATE_H
 #define JANSSON_PRIVATE_H
 
+#include <stddef.h>
 #include "jansson.h"
 #include "hashtable.h"
 
 #define container_of(ptr_, type_, member_)  \
-    ((type_ *)((char *)ptr_ - (size_t)&((type_ *)0)->member_))
+    ((type_ *)((char *)ptr_ - offsetof(type_, member_)))
 
 typedef struct {
     json_t json;