Fwd: $XDG_RUNTIME_DIR

[David Faure]

On Wednesday 05 December 2012 22:31:22 Thomas Kluyver wrote:
> On 5 December 2012 22:14, David Faure <faure at kde.org> wrote:
> > OK, so /run/user/ is a better default, when available, than /tmp, I'll
> > adjust
> > my code. Thanks for pointing this out, it looks like I didn't take this
> > into
> > account.
> 
> /run/user was created for this use, though, so systems that don't have
> $XDG_RUNTIME_DIR set probably won't have /run/user. My Ubuntu 12.04
> installation doesn't have either, while 12.10 does have both. And you can't
> create a directory in /run, because it's not user-writable.

Right. And I just discovered that Debian unstable still has neither the env 
var nor the directory.
But I really hope this is temporary...  Does anyone know when Debian will set 
XDG_RUNTIME_DIR?

> > I went too far in one direction (fallback without warning), you're going 
> > too
> > far into the other one (no fallback), I think we should both do what the
> > spec
> > says: fallback, with a warning :-)
> 
> I'm still not convinced that I am going too far. The runtime directory is
> supposed to have a very precisely specified set of properties that
> application authors can depend on. Silently (a stderr warning is all but
> silent for GUI developers) falling back to a substitute that
> *probably*offers *most* of the same features sounds like a recipe for hard
> to find bugs and security holes. I think there's a real argument for
> forcing application developers to think about the problem themselves.

I have re-read the original discussion about XDG_RUNTIME_DIR, and the item 
about "must be cleaned up on logout" seems a bit secondary to me, and mostly 
to make things cleaner and simpler.
http://lists.freedesktop.org/archives/xdg/2010-November/011694.html
In other words, not really a security risk there.

Using /tmp for user-specific session sockets is what we've been doing for 
decades, I don't think we should break apps just because the user's OS doesn't 
have yet the fancy new /run/user directory. 

> Also, while it's unclear how this will be used, I'm inclined to be
> conservative. If consensus develops on a suitable fallback, I can add a
> wrapper function to use it. But if I provide a fallback and later decide it
> was a mistake, removing it would break a lot of code.

I have to admit, that an application aborting due to no XDG_RUNTIME_DIR is 
exactly what made ubuntu implement it...
https://bugs.launchpad.net/ubuntu/+source/weston/+bug/1029223 pushed
https://bugs.launchpad.net/ubuntu/+source/pam-xdg-support/+bug/894391
to be implemented, it would seem.

Strange that this behavior of "weston" didn't make debian do the same...

-- 
David Faure, faure at kde.org, http://www.davidfaure.fr
Working on KDE, in particular KDE Frameworks 5