[Development] glib's and Qt's RuntimeLocation [OS X]

[Thiago Macieira]

On Tuesday 24 November 2015 19:58:22 René J. V. Bertin wrote:
> I'd have chosen $TMPDIR (aka QDir::tempPath()) myself. Contrary to 
> ~/Library/Cache that one is cleared on each reboot, which seems advantageous
> at  least for the kind of things RuntimeLocation is used for in
> FOSS/Freedesktop applications.

It mustn't be $TMPDIR. It needs to be a directory owned by the user so no 
other users can create files or sockets or FIFOs in there (no chance for 
malicious collision).

It could be a subdir of $TMPDIR, but then we run into a race condition problem 
of creating a secure subdir with a well-established name among applications. 
That's why the XDG spec says that XDG_RUNTIME_DIR *must* have been created 
when the user logs in and must be removed when the user fully logs out.

The fallback option that QStandardDirs offers when XDG_RUNTIME_DIR isn't set 
has those problems: it has race conditions and, because of that, it isn't 
secure.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center