Add a macro to accurately calculate the length of a struct ifreq when

it contains an address.  This can replace all the myriad (wrong) ways
in which this task is performed in the current system.  As an added
bonus, since it's a macro, then third-party software vendors have an easy
way to tell whether it's there or not.  (This will become necessary
when sizeof(struct sockaddr) is increaased, and also when additional
fields are added to struct ifreq.)

1 files changed, 6 insertions, 1 deletions

diff --git a/sys/net/if.h b/sys/net/if.h
index 0fe9205..0a7a48e 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)if.h	8.1 (Berkeley) 6/10/93
- *	$Id: if.h,v 1.46 1997/05/03 21:07:12 peter Exp $
+ *	$Id: if.h,v 1.47 1997/10/12 20:25:11 phk Exp $
  */
 
 #ifndef _NET_IF_H_
@@ -167,6 +167,11 @@ struct	ifreq {
 #define	ifr_data	ifr_ifru.ifru_data	/* for use by interface */
 };
 
+#define	_SIZEOF_ADDR_IFREQ(ifr) \
+	((ifr).ifr_addr.sa_len > sizeof(struct sockaddr) ? \
+	 (sizeof(struct ifreq) - sizeof(struct sockaddr) + \
+	  (ifr).ifr_addr.sa_len) : sizeof(struct ifreq))
+
 struct ifaliasreq {
 	char	ifra_name[IFNAMSIZ];		/* if name, e.g. "en0" */
 	struct	sockaddr ifra_addr;