From owner-freebsd-hackers@freebsd.org  Sat Apr  7 08:17:31 2018
Return-Path: <owner-freebsd-hackers@freebsd.org>
Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 90646F962F4
 for <freebsd-hackers@mailman.ysv.freebsd.org>;
 Sat,  7 Apr 2018 08:17:31 +0000 (UTC)
 (envelope-from phk@critter.freebsd.dk)
Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222])
 by mx1.freebsd.org (Postfix) with ESMTP id 1267E76096;
 Sat,  7 Apr 2018 08:17:30 +0000 (UTC)
 (envelope-from phk@critter.freebsd.dk)
Received: from critter.freebsd.dk (unknown [192.168.55.3])
 by phk.freebsd.dk (Postfix) with ESMTP id D8076273D5;
 Sat,  7 Apr 2018 08:17:29 +0000 (UTC)
Received: from critter.freebsd.dk (localhost [127.0.0.1])
 by critter.freebsd.dk (8.15.2/8.15.2) with ESMTPS id w378HTMB037080
 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO);
 Sat, 7 Apr 2018 08:17:29 GMT (envelope-from phk@critter.freebsd.dk)
Received: (from phk@localhost)
 by critter.freebsd.dk (8.15.2/8.15.2/Submit) id w378HTbw037079;
 Sat, 7 Apr 2018 08:17:29 GMT (envelope-from phk)
To: Roman Bogorodskiy <novel@FreeBSD.org>
cc: freebsd-hackers@freebsd.org
Subject: Re: Getting /dev entry by interface name
In-reply-to: <20180407025807.GA18883@kloomba>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
References: <20180407025807.GA18883@kloomba>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <37077.1523089049.1@critter.freebsd.dk>
Date: Sat, 07 Apr 2018 08:17:29 +0000
Message-ID: <37078.1523089049@critter.freebsd.dk>
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.25
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers/>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 07 Apr 2018 08:17:31 -0000

--------
In message <20180407025807.GA18883@kloomba>, Roman Bogorodskiy writes:

>1. Create tap(4) like that:
>
># ifconfig tap create
>tap2
>#
>
>2. Rename it
>
># ifconfig tap2 name testif
>testif
>
>Now I can do 'ifconfig testif' and there'll be no signs that it was
>named 'tap2' previously, however, in /dev it's still /dev/tap2.

I would argue that is an error.

The /dev entry should also be renamed, or maybe better, a symlink
with the new name should be created, pointing to the /dev/tap%d
entry.

However, I dont know if that is actually possible, is the device
driver even even told about the new interface name ?

There is also a name-space validation issue to think about:

	ifconfig tap2 name ../etc

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.