Subject: Re: bug#59474: Guix Home generated .profile sets XDG_ vars that break GDM+Gnome login on foreign distros

From: Andrew Tropin <[email-masked]>
Date: Tue, 13 Dec 2022 09:22:07 +0400

On 2022-11-22 08:09, Liliana Marie Prikler wrote:

> Am Montag, dem 21.11.2022 um 22:02 -0800 schrieb Matt Armstrong:
>> The first thing I see is that $HOME/.guix-home/seutp-environment is
>> modifying various XDG_ variables incorrectly.  It prepends new values
>> without honor the variable's default value if it doesn't happen to be
>> set already.
> This is a known problem with Debian.  Unlike Ubuntu, which relies on
> Flatpak and Snaps for its basic operations, Debian doesn't and hence
> hasn't set up these variables explicitly.  Note that this isn't unique
> to Guix Home or even just Guix.
>
>> For example, if XDG_DATA_DIRS is not set its default value is
>> "/usr/local/share/:/usr/share/".
> None of these directories exist in Guix System.  Assuming them would be
> a fault.  Note that the install script you're meant to use already
> initializes these variables since July [1].
>

I understand the inconvinience, but not sure that it has to be fixed on
Guix Home side.  According to the specification it's a fallback value
not a default value.

--8<---------------cut here---------------start------------->8---
If $XDG_DATA_DIRS is either not set or empty, a value equal to
/usr/local/share/:/usr/share/ should be used.
--8<---------------cut here---------------end--------------->8---

XDG_DATA_DIRS is not empty in our case and hence /usr/local/share and
/usr/share doesn't have to be used.  If it's critical for operation it
should be set before ~/.guix-home/setup-environment called, I would say
it looks like a debian bug, not Guix Home.  They same thing is true for
XDG_CONFIG_DIRS.

>> XDG_STATE_HOME is set to a non-standard value.  In the current XDG
>> Base Directory Specification it defaults to "$HOME/.local/state", but
>> Guix Home sets it to "$HOME/.local/var/lib".
> This is a genuine bug with Guix Home.
>
>> XDG_LOG_HOME is a non-standard variable.  The spec suggests that logs
>> should go in XDG_STATE_HOME.  Why not a establish a GUIX_LOG_HOME
>> variable instead?  (if it ever does become a standard XDG variable,
>> its default may not be the same one picked by Guix Home, causing the
>> same issue as above).
> Another genuine bug with Guix Home, although the variable does predate
> our support for XDG_STATE_HOME.  I suggest finding all uses of this
> variable in Guix Home and replacing them accordingly.
>

XDG_STATE_HOME and XDG_LOG_HOME apppeared in Guix Home before they were
described in xdg base directory specification, so the values was picked
to mimic FHS.  Probably they should be adjusted to the values defined in
specification.

>> Setting XDG_RUNTIME_DIR is not something I would expect Guix Home to
>> do -- it is the job of whatever logs the user in.
> I'm unsure about that one.
>

If it's set by elogind or whatever - cool, we will use value provided,
if not we explicitly set it, looks ok to me.

>> XDG_CACHE_HOME, XDG_CONFIG_HOME, XDG_DATA_HOME are set to their
>> defaults unnecessarily.
> Explicit is better than implicit.
>
> Cheers
>
>
> [1]
> http://git.savannah.gnu.org/cgit/guix.git/commit/?id=23aafc800c9e678662766440916449ec5bbce830
>
>
>
>

-- 
Best regards,
Andrew Tropin