Re: [PATCH 1/1] linux ttyname: return link if appropriate

[Serge Hallyn <serge dot hallyn at ubuntu dot com>]

Quoting Florian Weimer (fweimer@redhat.com):
> On 04/15/2016 05:29 PM, Serge Hallyn wrote:
> >The current ttyname does the wrong thing in two cases:
> >
> >1. If the passed-in link (say /proc/self/fd/0) points to a
> >device, say /dev/pts/2, in a parent mount namespace, and a
> >/dev/pts/2 exists (in a different devpts) in the current
> >namespace, then it returns /dev/pts/2.  But /dev/pts/2 is
> >NOT the current tty, it is a different file and device.
> 
> Is this the first change?

Right, it ensures that the filesystem of the two files is
the same.

> >2. If the passed-in link (say /proc/self/fd/0) points to
> >a device, say /dev/pts/2, in a parent mount namespace, and
> >/dev/pts/2 does not exist in the current namespace, it
> >returns success but an empty name.  As far as I can tell,
> >there is no reason for it to not return /proc/self/fd/0.
> >http://pubs.opengroup.org/onlinepubs/009695399/functions/ttyname.html
> >does not say anything about not returning a link.
> 
> Is it safe to drop the verification that ttyname ordinarily would do?

Which verification do you mean exactly?

> ttyname_r will need a similar change.

Oh, yeah, it will.

thanks,
-serge