Message-ID: <3BC3DE5D.8000500@wipro.com>
Date: Wed, 10 Oct 2001 11:06:29 +0530
From: "BALBIR SINGH" <balbir.singh@wipro.com>
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To: "David S. Miller" <davem@redhat.com>
CC: alan@lxorguk.ukuu.org.uk, torvalds@transmeta.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Trivial patch for SIOCGIFCOUNT
In-Reply-To: <3BC2FA63.6070006@wipro.com> <20011009.153746.59466398.davem@redhat.com>
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David S. Miller wrote:

>   From: "BALBIR SINGH" <balbir.singh@wipro.com>
>   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.
>
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

>
>Franks a lot,
>David S. Miller
>davem@redhat.com
>
>


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