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Date: Tue, 19 Apr 2016 17:18:26 -0700
Message-ID: <CA+55aFx8dKi7bvuqwPg_wjhTWtyty=u8fqxqsJuTHhVLjpJH6Q@mail.gmail.com>
Subject: Re: Does anyone care about a race free ptsname?
From: Linus Torvalds <torvalds@linux-foundation.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
        Andy Lutomirski <luto@amacapital.net>, security@debian.org,
        "security@kernel.org" <security@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        "security@ubuntu.com >> security" <security@ubuntu.com>,
        Peter Hurley <peter@hurleysoftware.com>,
        Serge Hallyn <serge.hallyn@ubuntu.com>, Willy Tarreau <w@1wt.eu>,
        Aurelien Jarno <aurelien@aurel32.net>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Jann Horn <jann@thejh.net>, Greg KH <greg@kroah.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jiri Slaby <jslaby@suse.com>, Florian Weimer <fw@deneb.enyo.de>
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On Tue, Apr 19, 2016 at 4:39 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>
> What do you think of the idea of TIOCPTSOPEN (or whatever) to get a file
> descriptor for the slave device given the master device?  Then we can
> use realpath() or a readlink on /proc/self/fd/# to get the pathname if
> needed.

That sounds reasonable to me.

> (Incidentally, we added getcwd() as a system call.  Should we add
> [f]realpath() as a system call too?)

Probably a good idea. It's kind of silly to have to do a sprintf
followed by a readlink().

              Linus