From 9fcee9da3f28b4b190d6976aeea72ab3c9f62bb2 Mon Sep 17 00:00:00 2001
From: Mark H Weaver <mhw@netris.org>
Date: Tue, 11 Mar 2014 20:31:38 -0400
Subject: [PATCH 1/1] Use 'offsetof' to avoid undefined behavior.

* libguile/socket.c (SUN_LEN): Use 'offsetof'.
---
 libguile/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libguile/socket.c b/libguile/socket.c
index c0faae1aa..5b17a741a 100644
--- a/libguile/socket.c
+++ b/libguile/socket.c
@@ -64,7 +64,7 @@
 
 
 #if defined (HAVE_UNIX_DOMAIN_SOCKETS) && !defined (SUN_LEN)
-#define SUN_LEN(ptr) ((size_t) (((struct sockaddr_un *) 0)->sun_path) \
+#define SUN_LEN(ptr) (offsetof (struct sockaddr_un, sun_path) \
 		      + strlen ((ptr)->sun_path))
 #endif
 
-- 
2.20.1