1 files changed, 7 insertions, 0 deletions
diff --git a/socket/sys/un.h b/socket/sys/un.h
index d88fa47069..02fc775acb 100644
--- a/socket/sys/un.h
+++ b/socket/sys/un.h
@@ -21,6 +21,8 @@
 #define	_SYS_UN_H	1
 #include <sys/cdefs.h>
 
+#include <string.h>		/* For prototype of `strlen'.  */
+
 /* Get the definition of the macro to define the common sockaddr members.  */
 #include <sockaddrcom.h>
 
@@ -33,6 +35,11 @@ struct sockaddr_un
     char sun_path[108];		/* Path name.  */
   };
 
+
+/* Evaluate to actual length of the `sockaddr_un' structure.  */
+#define SUN_LEN(ptr) (((struct sockaddr_un *) 0)->sun_path		      \
+		      + strlen ((ptr)->sun_path))
+
 __END_DECLS
 
 #endif	/* sys/un.h  */