[FFe, MIR] support $XDG_RUNTIME_DIR

Status changed to 'Confirmed' because the bug affects multiple users.

Unassigning while https://blueprints.launchpad.net/ubuntu/+spec/foundations-q-xdg-runtime-dir is being discussed (this might not even end up in CK)

XDG_RUNTIME_DIR not being set affects Weston.
See bug #1029223

step 1 is to get /run/user mounted by default.

This bug was fixed in the package mountall - 2.40

---------------
mountall (2.40) unstable; urgency=low

  * Add /run/user as a default mountpoint, in support of $XDG_RUNTIME_DIR.
    LP: #894391.

mountall (2.39) unstable; urgency=low

  * Adjust parsing of device names so that network mounts pointing to the
    server's root don't have the path mis-normalized to the empty string.
    Thanks to Damien Churchill <email address hidden> for the initial
    implementation. LP: #809221.
  * Add compatibility jobs with names to match the historic sysvinit init
    scripts, so that startpar can DTRT.
 -- Steve Langasek <email address hidden> Fri, 31 Aug 2012 19:55:01 -0700

I've just uploaded a new package, pam-xdg-support, to quantal and am seeking a FFe for it. This is a small module which handles the setup and teardown of the XDG_RUNTIME_DIR, addressing a long-standing bug report from the desktop team. It should be suitable for inclusion in the default PAM stack on the desktop.

The other options where this could have been implemented were pam_ck_connector and pam_systemd, but neither was suitable, hence the new package.

 - pam_ck_connector and pam_systemd are both designed to be used for login sessions only. That's insufficient for XDG_RUNTIME_DIR, which needs to be updated each time there's a user context change (e.g., sudo/su) because the pointed-to directory is, by definition, only writable by the owning user.
 - pam_systemd depends on systemd logind for the directory management, and logind is deeply intertwined with the systemd-specific cgroups layout which we do not want to adopt at this time.

The pam module is short (320 loc) and I hope sufficiently auditable that it can be included in quantal.

FFe apparently means FeatureFreeze Exception, I didn't know that.
Just in case anyone is wondering.

I hope we can get a FFe for this package.

Until then, is the package available in any PPA or anywhere?

The desktop team would like to see that FFe considered for quantal, without it libdconf (our default library to handle desktop settings) is sometimes hitting a SIGBUS for ecryptfs,nfs users (the most reported issue on nautilus during the precise cycle was due to that).

Approving the FFe itself, pending the usual NEW review and audit process.

$ sudo apt-get install libpam-xdg-support

Just tried it and it works.
Weston now runs without any complaints.

Maybe this could be marked as a supported package?
Maybe this could be installed by default?

ACK from the security team, code looks good.

I'll give this a MIR lookover.

Nevermind, doko did that already. Whoops. :)

and promoted ...

Override component to main
pam-xdg-support 0.1-0ubuntu1 in quantal: universe/admin -> main
libpam-xdg-support 0.1-0ubuntu1 in quantal amd64: universe/admin/optional -> main
libpam-xdg-support 0.1-0ubuntu1 in quantal armel: universe/admin/optional -> main
libpam-xdg-support 0.1-0ubuntu1 in quantal armhf: universe/admin/optional -> main
libpam-xdg-support 0.1-0ubuntu1 in quantal i386: universe/admin/optional -> main
libpam-xdg-support 0.1-0ubuntu1 in quantal powerpc: universe/admin/optional -> main
6 publications overridden.

Is this going to be installed by default?

According to comments in bug 1058211, this will be installed by default as a dependency of ubuntu-desktop.

The ubuntu-desktop package in quantal now has a dependency on libpam-xdg-support, so everyone will get this by default.

XDG_CONFIG_HOME is not set tho.