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Date: Sun, 23 May 2004 06:35:38 +0100
From: viro@parcelfarce.linux.theplanet.co.uk
To: Joshua Kwan <joshk@triplehelix.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: consistent ioctl for getting all net interfaces?
Message-ID: <20040523053538.GW17014@parcelfarce.linux.theplanet.co.uk>
References: <pan.2004.05.23.04.28.28.143054@triplehelix.org>
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On Sat, May 22, 2004 at 09:28:28PM -0700, Joshua Kwan wrote:
> Hi,
> 
> I'm interested in not having to parse /proc/net/dev to get a list of all
> available (not necessarily even up) interfaces on the system. I
> investigated the ioctl SIOCGIFCONF, but it seems to behave differently on
> 2.4 and 2.6 series kernels, e.g. sometimes it won't return all interfaces.
> 
> Is there some end-all ioctl that does what I want, or am I forever doomed
> to process /proc/net/dev (in C, no less..)?

ASCII is tough, let's go shopping?

	char name[17];
	FILE *in = fopen("/proc/net/dev", "r");
	if (!in)
		die("can't open");
	fscanf(in, "%*[^\n]\n%*[^\n]");		/* skip two lines */
	while (fscanf(in, " %16[^:]:%*[^\n]", name) == 1)
		do_whatever_you_want(name);

That you are calling "forever doomed"?  Wimp...