x.org server fails to start when $TMPDIR is set

[Stephen M. Webb]

When the Xmir server is run on a device or desktop under Unity 8 it fails to start with the following error messages.

  [xkb] Can't rename /run/user/32011/confined/com.ubuntu.sdk/fileSgDXpU to /tmp/server-B20D7FC79C7F597315E3E501AEF10E0D866E8E92.xkm, error: Invalid cross-device link
  XKB: Failed to compile keymap
  Keyboard initialization failed. This could be a missing or incorrect setup of xkeyboard-config.
  (EE) Fatal server error:
  (EE) Failed to activate core devices.(EE)

We traced the problem down to the fact that the $TMPDIR is set in the environment and points to a confined location in the /run filesystem, and x.org uses the hardcoded path of /tmp which is a different filesystem. A Ubuntu-specific patch to the x.org server attempts to rename the .xkm file across filesystems (which is not allowed).

To avoid this error the Ubuntu-speicific patch to cache the xkb file should also patch the hardcoded /tmp to use $TMPDUR if it is set.

[Launchpad Janitor (janitor)]

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

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 972324, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.