Gdk::Pixbuf->new_from_file hangs with gdk-pixbuf v2.44

[davidfoerster]

Observed behaviour
When starting GMB no graphical user interface appears. It's quite obviously running (see debug log) but there's no window associated with it.

Expected behaviour
When starting GMB, a window with a graphical user interface appears.

Other information

• I'm running the master branch (commit 75c410d as of writing) on Arch Linux.
• The appearance of the issue coincides with the release and installation of GNOME Shell 49.
• The issue appears even with an empty config directory and disabled plugins (see below).

I produced a debug log with the command sequence

cfg=$TMP/gmb
rm -rf $cfg
mkdir $cfg
LC_ALL=C gmusicbrowser -debug -demo -nogst -nodbus -noplugins -c $cfg |& tee gmb.log

but I see no relevant entries in it.

I suspect that the GNOME Shell 49 released introduced an API or ABI change that affects GMB either directly or indirectly (via Perl's GKT3 bindings) but I know too little about both Perl and GTK for a targeted investigation. Although with some direction I'm willing and hopefully capable enough to conduct one.

[davidfoerster]

Some further investigation:

• On Wayland, GMB does not appear in the list of windows.

• On X.org via Wayland, GMB doesn't open a window either but X.org is aware of one.

  $ GDK_BACKEND=x11 gmusicbrowser -demo &
  [...]
  $ xlsclients -l
  [...]
  Window 0xc00001:
    Machine:  ernesto
    Name:  gmusicbrowser
    Icon Name:  gmusicbrowser
    Command:  gmusicbrowser
    Instance/Class:  gmusicbrowser/Gmusicbrowser
  [...]
  

[bucaneer]

Same issue here.

Starting gmusicbrowser.pl from console and then closing it with Ctrl+C produces a stacktrace which indicates that the program is getting stuck in function GMB::Picture::load. Specifically this line (if running git master) which calls the Gtk3::Gdk::Pixbuf library.

The issue with gmusicbrowser appeared after upgrading gdk-pixbuf2 package from version 2.42 to version 2.44. Downgrading back to 2.42 is a workaround that fixes the issue.

Don't know whether this is a bug on Gdk side or a breaking change that needs to be addressed in gmusicbrowser.

[davidfoerster]

@bucaneer Good find!

I've been scrolling through recent GNOME and GTK bugs a bit to find anything that fits and image decoding seems to have been an issue. Among other things I noticed an architecture change in gdk-pixbuf: it will now decode images in a locked-down child process via Glycin by default.

[davidfoerster]

I was able to build a small example to at least prove that pixbuf and image loading still work with Perl-Gtk3.

gdk_pixbuf_new_from_file.pl.txt

[Chaosmos404]

Instead of downgrading gdk-pixbuf2, it can be replaced with gdk-pixbuf2-noglycin along with the librsvg-noglycin, at least for the time being until this problem is fixed.
https://bbs.archlinux.org/viewtopic.php?pid=2267739

Hopefully this will be solved in a reasonable timeframe.

[iGormilhit]

@Chaosmos404 Thanks a lot for this valuable piece of information!

[trasher]

I have the same issue... But that's not possible for me to downgrade gdk-pixbuf2 (I'm running Fedora 43) :/

[yennor]

in debian, gdk-pixbuf2 will not be provided without glycin, see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1128001&mboxmaint=no#49

For the moment being downgrade is still possible on debian testing, but sooner or later one will run into dependencies issues.
So gmusicbrowser would need to be changed,