From: Andreas Schwab <schwab@suse.de>
Date: Mon, 19 Sep 2022 08:10:09 +0000 (+0200)
Subject: socket: Use offsetof in SUN_LEN (bug 29578)
X-Git-Tag: upstream/2.37~265
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c15318bfc5499d835c434a4d98b688aa2d928412;p=platform%2Fupstream%2Fglibc.git

socket: Use offsetof in SUN_LEN (bug 29578)

Use offsetof instead of its traditional expansion in the definition of the
SUN_LEN macro, to avoid a warning from the undefined behaviour sanitizer.
---

diff --git a/socket/sys/un.h b/socket/sys/un.h
index 454eafe..2b11300 100644
--- a/socket/sys/un.h
+++ b/socket/sys/un.h
@@ -34,10 +34,11 @@ struct sockaddr_un
 
 
 #ifdef __USE_MISC
+# include <stddef.h>
 # include <string.h>		/* For prototype of `strlen'.  */
 
 /* Evaluate to actual length of the `sockaddr_un' structure.  */
-# 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