X-Recipient: archive-cygwin AT delorie DOT com
DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:date:from:to:subject:message-id:reply-to
	:references:mime-version:content-type:in-reply-to; q=dns; s=
	default; b=P6AuA4iNmKMOoxlFpdqDf2xd81Br6CN6tHmTcxy/c2nQQdaFUTV0Z
	Hqd+U0zhLz9WJCIpr6+ZFiG7MjJe1q3MxZEHxnNrls88UYqbEjcoyWNTSd62SWWX
	4boi28e6Ihw8Q0V5ovXHAd/BKAl7hOGauophnFd7zzfw9tPbdLUlDM=
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:date:from:to:subject:message-id:reply-to
	:references:mime-version:content-type:in-reply-to; s=default;
	 bh=18HYLoY+uncqxGpzCUyUMy75KzQ=; b=um1QkRCdw5ukLESDiA5WEkSmxb3M
	FlNrkgaWZSzi+JqfK7GoOa5DHFVOGvub4ohe4edpG0d2GFtvobE747KwbGLusUVM
	K7zOTEcHbVdL8cB0BiKrLQg7TQcykPI6WuUAMrN4JzGr+6Du9pX99IntOvA4m6mn
	IagBQxGAlAKCBGw=
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id: <cygwin.cygwin.com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Authentication-Results: sourceware.org; auth=none
X-Virus-Found: No
X-Spam-SWARE-Status: No, score=-5.9 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.3.2
X-HELO: calimero.vinschen.de
Date: Tue, 10 Feb 2015 19:26:45 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: /dev/tty does not work from shell
Message-ID: <20150210182645.GE2866@calimero.vinschen.de>
Reply-To: cygwin AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
References: <54DA31C1 DOT 9060406 AT redhat DOT com> <54DA32D9 DOT 5070909 AT redhat DOT com> <20150210174647 DOT 7760EAC0 DOT helmut DOT karlowski AT ish DOT de> <54DA411E DOT 3040700 AT redhat DOT com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1;	protocol="application/pgp-signature"; boundary="/3yNEOqWowh/8j+e"
Content-Disposition: inline
In-Reply-To: <54DA411E.3040700@redhat.com>
User-Agent: Mutt/1.5.23 (2014-03-12)

--/3yNEOqWowh/8j+e
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Feb 10 10:34, Eric Blake wrote:
> On 02/10/2015 09:46 AM, Helmut Karlowski wrote:
> >> The same test from the command line:
> >>
> >> $ stat -c %i /dev/tty - 0>/dev/tty
> >> 327680
> >> 8912896
> >>
> >> use any other (already-existing) file to see that the two numbers shou=
ld
> >> normally be the same.
> >=20
> > Don't know why, but cygwin is not the only OS that does that. I'd=20
> > suggest to check for terminal or something.
>=20
> Umm, what other OS changes the inode from what you called stat() on to
> what you open()d?  Okay, there are some special device files like
> /dev/ptmx that intentionally create a new device (and therefore new
> inode) every time it is opened, but is /dev/tty in that boat?  POSIX
> requires /dev/tty to resolve to the process's controlling terminal.
>=20
> If there _are_ other OS that change the inode of the fd returned by
> opening /dev/tty, that argues that any change in bash to special-case
> /dev/tty should be made upstream, so I'm reluctant to write a
> cygwin-specific bash patch.  If there aren't other OS that change the
> inode of /dev/tty, then it's better to figure out how to patch
> cygwin1.dll to be more like Linux.

That's that.  The other is that the way /dev/tty works on Linux and
Cygwin is different.  On Linux you open /dev/tty and the kernel
redirects all calls to the descriptor to your current controlling tty.
On Cygwin you open /dev/tty and the open call itself is redirected to
an open call of your current ctty.  That doesn't naturally mean that
the stat/fstat inode numbers must be different, but they are right now
due to the underlying behaviour.

Whatever POSIX has to say about /dev/tty, I don't think this really
qualifies as a bug.  There are apparently just a couple of ingrained
expectations floating around...


Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

--/3yNEOqWowh/8j+e
Content-Type: application/pgp-signature

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
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=ZXTC
-----END PGP SIGNATURE-----

--/3yNEOqWowh/8j+e--