Trivial patch for SIOCGIFCOUNT

Hello Linus, Alan, David,
To make the API orthogonal, I have included a patch for SIOCGIFCOUNT,
which currently returns -EINVAL. The only reason I am providing this patch is to make the API complete and make it easier to port applications from other UNIX like OS'es.

I have verified and am sure that this patch works. The priority of this patch is not very high, but it would be good to have a orthogonal/complete API.

The patch is against 2.4.2-2 (official rh 7.1). I can provide one against 2.4.10 or 2.4.10-pre16 if required.

@@ -1651,6 +1651,40 @@

}

/*
+ * Implement the SIOCGIFCOUNT, ioctl to keep the API orthogonal.
+ * Basically taken from dev_ifconf - Balbir
+ */
+static int dev_ifcount(char *arg)
+{

+       struct net_device *dev;
+       int i;
+       unsigned int total;
+
+       total = 0;
+       /*
+        * May be introducing something like for_each_netdev(dev)
+        * on the lines of for_each_pci_dev would be useful here.
+        */

+ for (dev = dev_base; dev != NULL; dev = dev->next) {
+ for (i = 0; i < NPROTO; i++) {
+ if (gifconf_list[i]) {
+ int done;
+
+ done = gifconf_list[i](dev, NULL, 0);
+ if (done < 0)
+ return -EFAULT;
+ total++;
+ }
+ }
+ }
+
+ if (copy_to_user(arg, &total, sizeof(int)))
+ return -EFAULT;
+
+ return 0;
+}
+
+/*
* This is invoked by the /proc filesystem handler to display a device
* in detail.
*/
@@ -2218,6 +2252,18 @@

               rtnl_shunlock();
               return ret;
       }
+
+       /*
+        * We do not need an exclusive lock for returning the count,
+        * shared lock is fine with us.
+        */
+       if (cmd == SIOCGIFCOUNT) {
+               rtnl_shlock();
+               ret = dev_ifcount((char *)arg);
+               rtnl_shunlock();
+               return ret;
+       }
+
       if (cmd == SIOCGIFNAME) {
               return dev_ifname((struct ifreq *)arg);
       }

Comments, rejections, etc
Balbir

----------------------------------------------------------------------------------------------------------------------
Information transmitted by this E-MAIL is proprietary to Wipro and/or its Customers and is intended for use only by the individual or entity to which it is addressed, and may contain information that is privileged, confidential or exempt from disclosure under applicable law. If you are not the intended recipient or it appears that this mail has been forwarded to you without proper authority, you are notified that any use or dissemination of this information in any manner is strictly prohibited. In such cases, please notify us immediately at mailto:[email protected] and delete this mail from your records.
----------------------------------------------------------------------------------------------------------------------

From: "BALBIR SINGH" <[email protected]>
Date: Tue, 09 Oct 2001 18:53:47 +0530

To make the API orthogonal, I have included a patch for SIOCGIFCOUNT,
which currently returns -EINVAL. The only reason I am providing this patch is to make the API complete and make it easier to port applications from other UNIX like OS'es.

There is no need for this change, and _EVEN_ if we put this change in today every APP out there would _STILL_ need to deal with all existing kernels which do not have SIOCGIFCOUNT implemented.

Furthermore, SIOCGIFCOUNT also gives no new functionality that does not exist already. SIOCGIFCONF with a zero size with give the behavior necessary to get the same answer as a SIOCGIFCOUNT would provide. As far as I am aware, every system providing BSD sockets provides this SIOCGIFCONF "feature".

Therefore, it is already quite easy to make applications portable between Linux and other BSD socket based systems. Simply use the SIOCGIFCONF method throughout.

Franks a lot,
David S. Miller
[email protected]

I had mentioned even earlier, the same functionality can be obtained otherwise. I was talking about porting from SUN, HP-UX, AIX, etc. I have had people coming to me and telling me that SIOCGIFNUM (equivalent to SIOCGIFCOUNT) does not exist and I have had to ask them to use SIOCGIFCONF, if ifc.ifc_len and ifc.ifc_buf set to '0', to obtain the total size. Again, it is not a must it should be around. But since the ioctl is there, it might be good to have it work the way some one reading a man page would expect it to work, or if somebody wanted to port some application from Sun, HP-UX or AIX would just do

#define SIOCGIFNUM SIOCGIFCOUNT

and get his application to compile without changing the code

Regards,
Balbir

----------------------------------------------------------------------------------------------------------------------
Information transmitted by this E-MAIL is proprietary to Wipro and/or its Customers and is intended for use only by the individual or entity to which it is addressed, and may contain information that is privileged, confidential or exempt from disclosure under applicable law. If you are not the intended recipient or it appears that this mail has been forwarded to you without proper authority, you are notified that any use or dissemination of this information in any manner is strictly prohibited. In such cases, please notify us immediately at mailto:[email protected] and delete this mail from your records.
----------------------------------------------------------------------------------------------------------------------

Hello!

Grrr.... Listen what the hell did you call this ioctl with _another_ name, absent both in BSD and in SVR4??? :-)

I remember the patch doing the same thing and I zapped this crap exactly because it was another linuxish hack moving from bsd api and not moving closer to svr4.

Alexey

PS. Well, and did you think about one thing: "linux" port of any application which does not work with linuxes can smell a bit anti-social for many people, who do not compile from sources. And for all the people, if the port is binary.