Subject: Re: bug#37123: gnome-shell: LD_LIBRARY_PATH setting propagates to entire session

From: Ludovic Courtès <[email-masked]>
Date: Wed, 13 Nov 2019 23:02:52 +0100

Hello,

Ricardo Wurmus <[email-masked]> skribis:

>> Since commit 2b0c755d195c79bfc95cdbe802e1e2dea1adb7a2 in August 2018,
>> our 'gnome-shell' executable has been wrapped by a script that sets
>> LD_LIBRARY_PATH.
>>
>> One consequence of this, which I just noticed, is that if 'gnome-shell'
>> is based on 'core-updates' (or in my case, 'core-updates-next'), many
>> programs based on 'master' will fail to run within the resulting GNOME
>> session.
> […]
>> I was unable to easily find an existing bug report tracking this issue,
>> so I created this one.
>
> There was no bug report about this, so thanks for reporting it.  I once
> brought this issue up on the mailing list here:
>
>     https://lists.gnu.org/archive/html/guix-devel/2019-05/msg00372.html

Looking at this bit in the ‘gnome-shell’ definition:

--8<---------------cut here---------------start------------->8---
     (wrap-program (string-append out "/bin/gnome-shell")
       `("GI_TYPELIB_PATH" ":" prefix (,gi-typelib-path))
       ;; FIXME: gnome-shell loads these libraries with unqualified
       ;; names only, so they need to be on LD_LIBRARY_PATH.  The
       ;; alternative might be to patch gnome-shell.
       `("LD_LIBRARY_PATH" ":" prefix
         ,(map (lambda (pkg)
                 (string-append (assoc-ref inputs pkg) "/lib"))
               '("gdk-pixbuf"
                 "gnome-bluetooth" "librsvg" "libgweather"))))
--8<---------------cut here---------------end--------------->8---

I checked in Gjs etc. how those imports (e.g., “imports.gi.Rsvg” in
Javascript) are turned into a dlopen.  AIUI, this is done by
gobject-introspection based on info found in .gir files.

In Guix, .gir files contain absolute file names of share libraries.  At
run-time, ‘gobject-introspection-absolute-shlib-path.patch’ ensures that
dlopen is passed absolute file names.

So, IIUC, “imports.gi.Rsvg” should lead to dlopen by absolute file name,
in which case setting LD_LIBRARY_PATH is useless.

However, does anyone know about we can test whether removing the
LD_LIBRARY_PATH wrapping above breaks something?

Thanks,
Ludo’.