Date: Thu, 12 Jan 2006 21:30:24 -0800 From: Brooks Davis <brooks@one-eyed-alien.net> To: freebsd-net@freebsd.org Subject: sized data in struct ifreq Message-ID: <20060113053023.GA21887@odin.ac.hmc.edu>
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I'd like to introduce a new entry in the union in struct ifreq
containing a pointer and a size. It would be used in place of ifr_data
in new ioctls. The problem with the ifr_data (pseudo) member is that it
encourages interfaces that encode the size of the data being passed
implicitly in the kernel ABI. There are ways around this such as making
the size the first element of the struct and doing a two copyin()s to
get the actual size, but that is no substitute for simply requiring the
specification of a size in the first place. I have verified that the
following change does not change the size of the struct on i386, amd64,
ia64, and alpha (panther is down so I can't check sparc64).
Are there any objections to this change? I plan to use it to add the
requested feature of interface descriptions. Here is a diff of possible
changes to if.h.
-- Brooks
Index: if.h
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
RCS file: /home/ncvs/src/sys/net/if.h,v
retrieving revision 1.99
diff -u -p -r1.99 if.h
--- if.h 1 Oct 2005 18:56:18 -0000 1.99
+++ if.h 13 Jan 2006 05:20:32 -0000
@@ -273,6 +273,10 @@ struct ifreq {
int ifru_media;
caddr_t ifru_data;
int ifru_cap[2];
+ struct {
+ void *data;
+ size_t len;
+ } ifrs_sdata;
} ifr_ifru;
#define ifr_addr ifr_ifru.ifru_addr /* address */
#define ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-to-p link */
@@ -283,7 +287,9 @@ struct ifreq {
#define ifr_mtu ifr_ifru.ifru_mtu /* mtu */
#define ifr_phys ifr_ifru.ifru_phys /* physical wire */
#define ifr_media ifr_ifru.ifru_media /* physical media */
-#define ifr_data ifr_ifru.ifru_data /* for use by interface */
+#define ifr_data ifr_ifru.ifru_data /* deprecated in new code */
+#define ifr_sdata ifr_ifru.ifru_sdata.data /* for use by interface */
+#define ifr_sdata_len ifr_ifru.ifru_sdata.len /* length of interface data =
*/
#define ifr_reqcap ifr_ifru.ifru_cap[0] /* requested capabilities */
#define ifr_curcap ifr_ifru.ifru_cap[1] /* current capabilities */
#define ifr_index ifr_ifru.ifru_index /* interface index */
--=20
Any statement of the form "X is the one, true Y" is FALSE.
PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4
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