[bug#76428] [GCD PATCH] 003-set-search-paths-without-program-wrappers: Submit.

[Ludovic Courtès]

Hello,

宋文武 <iyzsong@envs.net> skribis:

> Yes, we introduced GUIX_PYTHONPATH, GUIX_GTK* to avoid ABI
> incompatibility problems between different programs from foreign systems
> and Guix systems.  But XDG_DATA_DIRS, as it's designed for shareable
> data files, won't have ABI incompatibility problems, and we rely on it
> for a foreign desktop launch to find applications (via desktop files),
> fonts installed from Guix.

(I hadn’t realized GUIX_GTK* and GUIX_GDK* already exist…)

> So do we need 'GUIX_XDG_*'?  Well, In 'wrap-program' we can specifiy how
> the wrapped environment variables are going to be combined with the
> system level variables in 3 positions: prefix, suffix or = (exact).  The
> priority between wrapped and system level variables influence the
> robustness of programs.
>
> For plugins which might have ABI problems, we'll use 'prefix', so a
> wrapped program always load the correct ones (eg: qtbase) first, and
> hopefully they can ignore the possible incompatible ones (eg: a qt
> theme plugin) with reduced functions but still works.
>
> Or for not real search paths which only support a single directory or
> file, we'll use '=' (eg: SSL_CERT_FILE).
>
> But for XDG_DATA_DIRS and XDG_CONFIG_DIRS, we'll want to use 'suffix',
> so that the shared combined data (icons, mime databases) will be used
> instead of a seperated incomplete ones.  Also it allow user to customize
> them as usually, or 'guix home' or 'guix system' to custom them at
> profile level.

I understand this, but I’m not sure how it releases to GUIX_-prefixing
more variables.

> In the specified search-paths.d implementation, for simplify reason, the
> envs from search-paths.d files are always used in 'prefix' way.  For '='
> cases, we could patch it to a real search path (eg:
> GUIX_GDK_PIXBUF_MODULE_FILES), or hardcode it (eg:
> QTWEBENGINEPROCESS_PATH #75966).  For 'suffix' cases, it uses 2
> variables, that's prefer XDG_DATA_DIRS (set by profile or foreign
> system) over GUIX_XDG_DATA_DIRS (set by search-paths.d, not leaking).

Uh.  Having GUIX_XDG_DATA_DIRS at all sounds like a problem to me.

>>>   - `GUIX_INTERPRETER_FILE`: absolute file name of the interpreter
>>>   - `GUIX_MAIN_SCRIPT_FILE`: absolute file name of the script
>>
>> We won’t patch every interpreter out there, that’s not reasonable.
>
> Yes, python should be the most, also we can avoid patching and still use
> 'wrap-program' for them.

Hmm OK.

>> Overall, I think I’d be reassured if we reduced the scope a little bit:
>> don’t insist on the “GUIX_” prefix, focus on GTK and Qt applications.
>
> Okay, I'll send GUIX_GIO_EXTRA_MODULES as a seperated patch later.  For
> 'GUIX_XDG_DATA_DIRS' and 'GUIX_XDG_CONFIG_DIRS', do you think the
> current implementation plan (GUIX_ ones only used by search-paths.d,
> only XDG_DATA_* still set by profile and visible, use 2 variables due to
> simplify reason) fine?

I’m not sure I fully understand what “only used by search-paths.d”
means; I would prefer not introducing any GUIX_-prefixed variable as
part of this work.  Adding these variables could be discussed
separately.

Thanks for explaining!

Ludo’.