Waybar 0.10.3, libcava 0.10.1, segfaults with cava module enabled in bar configuration

[OriginCode]

Tested with --buildtype=debug.

waybar -l trace:

[2024-05-16 02:15:30.380] [debug] Try expanding: $XDG_CONFIG_HOME/waybar/config
[2024-05-16 02:15:30.380] [debug] Try expanding: $XDG_CONFIG_HOME/waybar/config.jsonc
[2024-05-16 02:15:30.380] [debug] Try expanding: $HOME/.config/waybar/config
[2024-05-16 02:15:30.380] [debug] Try expanding: $HOME/.config/waybar/config.jsonc
[2024-05-16 02:15:30.380] [debug] Found config file: $HOME/.config/waybar/config.jsonc
[2024-05-16 02:15:30.380] [info] Using configuration file /home/origincode/.config/waybar/config.jsonc
[2024-05-16 02:15:30.385] [info] Discovered appearance 'dark'
[2024-05-16 02:15:30.385] [debug] Try expanding: $XDG_CONFIG_HOME/waybar/style-dark.css
[2024-05-16 02:15:30.385] [debug] Try expanding: $XDG_CONFIG_HOME/waybar/style.css
[2024-05-16 02:15:30.385] [debug] Try expanding: $HOME/.config/waybar/style-dark.css
[2024-05-16 02:15:30.385] [debug] Try expanding: $HOME/.config/waybar/style.css
[2024-05-16 02:15:30.385] [debug] Found config file: $HOME/.config/waybar/style.css
[2024-05-16 02:15:30.385] [info] Using CSS file /home/origincode/.config/waybar/style.css
[2024-05-16 02:15:30.393] [debug] Output detection done: DP-1 (GSM LG ULTRAGEAR 0x0001D493)
[2024-05-16 02:15:30.395] [warning] Mapping is not an object
fish: Job 1, './build/waybar -l trace' terminated by signal SIGSEGV (Address boundary error)

gdb waybar:

(gdb) bt
#0  __GI_strlen () at ../sysdeps/x86_64/multiarch/strlen-sse2.S:142
#1  0x0000555555593d2f in std::char_traits<char>::length (__s=0x0) at /usr/include/c++/13.2.0/bits/char_traits.h:409
#2  0x00005555557f0e34 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::replace (this=0x7fffffffb4f0, __pos=0, __n1=16, __s=0x0)
    at /usr/include/c++/13.2.0/bits/basic_string.h:2221
#3  0x00005555557ee2f5 in waybar::modules::Cava::Cava (this=0x555555cc3570, id="", config=...) at ../src/modules/cava.cpp:15
#4  0x0000555555591fde in waybar::Factory::makeModule (this=0x7fffffffc8c0, name="cava", pos="modules-left") at ../src/factory.cpp:311
#5  0x0000555555618ade in waybar::Bar::getModules (this=0x555555addda0, factory=..., pos="modules-left", group=0x0) at ../src/bar.cpp:495
#6  0x00005555556190e0 in waybar::Bar::setupWidgets (this=0x555555addda0) at ../src/bar.cpp:543
#7  0x00005555556167b2 in waybar::Bar::Bar (this=0x555555addda0, w_output=0x555555bca1c0, w_config=...) at ../src/bar.cpp:279
#8  0x0000555555631a74 in std::make_unique<waybar::Bar, waybar::waybar_output*, Json::Value const&> () at /usr/include/c++/13.2.0/bits/unique_ptr.h:1070
#9  0x000055555562523a in waybar::Client::handleOutputDone (data=0x555555bca1c0) at ../src/client.cpp:83
#10 0x00007ffff65a6052 in ffi_call_unix64 () at ../src/x86/unix64.S:104
#11 0x00007ffff65a4917 in ffi_call_int (cif=cif@entry=0x7fffffffcf70, fn=fn@entry=0x5555556250ee <waybar::Client::handleOutputDone(void*, zxdg_output_v1*)>, rvalue=<optimized out>,
    rvalue@entry=0x0, avalue=<optimized out>, closure=closure@entry=0x0) at ../src/x86/ffi64.c:673
#12 0x00007ffff65a504d in ffi_call
    (cif=cif@entry=0x7fffffffcf70, fn=0x5555556250ee <waybar::Client::handleOutputDone(void*, zxdg_output_v1*)>, rvalue=rvalue@entry=0x0, avalue=avalue@entry=0x7fffffffd040)
    at ../src/x86/ffi64.c:710
#13 0x00007ffff7f7b6e1 in wl_closure_invoke (closure=closure@entry=0x555555b22f00, flags=flags@entry=1, target=<optimized out>,
    target@entry=0x555555adcfe0, opcode=opcode@entry=2, data=<optimized out>) at ../src/connection.c:1025
#14 0x00007ffff7f77be8 in dispatch_event (display=display@entry=0x5555559af380, queue=0x5555559af470) at ../src/wayland-client.c:1631
#15 0x00007ffff7f79534 in dispatch_queue (queue=0x5555559af470, display=0x5555559af380) at ../src/wayland-client.c:1777
#16 wl_display_dispatch_queue_pending (display=0x5555559af380, queue=0x5555559af470) at ../src/wayland-client.c:2019
#17 0x00007ffff7f7958c in wl_display_dispatch_pending (display=<optimized out>) at ../src/wayland-client.c:2082
#18 0x00007ffff76da044 in _gdk_wayland_display_queue_events (display=<optimized out>) at ../gdk/wayland/gdkeventsource.c:201
#19 0x00007ffff76a83f9 in gdk_display_get_event (display=0x5555559d3480 [GdkWaylandDisplay]) at ../gdk/gdkdisplay.c:442
#20 0x00007ffff76e2a12 in gdk_event_source_dispatch (base=<optimized out>, callback=<optimized out>, data=<optimized out>) at ../gdk/wayland/gdkeventsource.c:120
#21 0x00007ffff6a95498 in g_main_dispatch (context=context@entry=0x5555559dbe60) at ../glib/gmain.c:3344
#22 0x00007ffff6a985a7 in g_main_context_dispatch_unlocked (context=0x5555559dbe60) at ../glib/gmain.c:4152
#23 g_main_context_iterate_unlocked (context=context@entry=0x5555559dbe60, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../glib/gmain.c:4217
#24 0x00007ffff6a98bac in g_main_context_iteration (context=context@entry=0x5555559dbe60, may_block=may_block@entry=1) at ../glib/gmain.c:4282
#25 0x00007ffff6cfb42d in g_application_run (application=0x5555559a4fe0 [gtkmm__GtkApplication], argc=<optimized out>, argv=<optimized out>) at ../gio/gapplication.c:2712
#26 0x00005555556275de in waybar::Client::main (this=0x55555591d780, argc=1, argv=0x7fffffffde48) at ../src/client.cpp:287
#27 0x0000555555611ef0 in main (argc=1, argv=0x7fffffffde48) at ../src/main.cpp:106

Seems to be related to config file loading?

[OriginCode]

Yeah it seems to be something wrong when $XDG_CONFIG_HOME is empty.

According to https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html , the value should default to $HOME/.config if not set.

[LukashonakV]

Yeah, need to add validation for $XDG_CONFIG_HOME.

[LukashonakV]

Hi @OriginCode , fix is merged. Please try again with the master branch

[OriginCode]

Hi @OriginCode , fix is merged. Please try again with the master branch

Yeah it doesn't segfault now as it just cannot find the file lol.

You might want to consider implement the spec to check $HOME/.config as a fallback. There are distros that do not manually set $XDG_CONFIG_HOME.

[LukashonakV]

Checking your point...

[LukashonakV]

Hi @OriginCode , thank you for your feedback. Related merge request is created to the original cava upstream. See karlstav/cava#565. Once it's done I'll do sync with libcava and bump libcava version.

[LukashonakV]

Hi @OriginCode , please check with the new commits. Now it should be fine. If it's so, please close the issue

[OriginCode]

@LukashonakV It still doesn't recognize $XDG_CONFIG_HOME when the variable is empty :(
Also there seems to be some weird issue in the log (see the path in the error message, it's not the same as in my config):

[LukashonakV]

Hi @OriginCode, can you explain what you're expecting from cava when the environment variable is not defined in the system ?
Thank you for response, I reproduced the issue with the garbage in the final config path. Need to check what's wrong with it.

[OriginCode]

@LukashonakV It should look for $HOME/.config as fallback to $XDG_HOME_CONFIG.

[LukashonakV]

Hi @OriginCode , I fixed the issue when libcava expands user variables and constructs file path for opening. Please update waybar or libcava-0.10.3 and let me know about results. Thanks

[OriginCode]

Hi @OriginCode , I fixed the issue when libcava expands user variables and constructs file path for opening. Please update waybar or libcava-0.10.3 and let me know about results. Thanks

I still get [error] Error loading config. Unable to open file '${XDG_CONFIG_HOME}/cava/cava.conf', exiting... with master branch waybar and libcava 0.10.3.

[LukashonakV]

@OriginCode you should use $XDG_CONFIG_HOME. NOT ${XDG_CONFIG_HOME}

[OriginCode]

@OriginCode you should use $XDG_CONFIG_HOME. NOT ${XDG_CONFIG_HOME}

Both don't work on my end. :(
[error] Error loading config. Unable to open file '$XDG_CONFIG_HOME/cava/cava.conf', exiting...

[LukashonakV]

This error means you have not configured xdg variable .
env | grep -i xdg

[OriginCode]

This error means you have not configured xdg variable . env | grep -i xdg

As I mentioned before, according to https://specifications.freedesktop.org/basedir-spec/latest/index.html#variables when the variable is not set, it should look up $HOME/.config as a fallback :)

[LukashonakV]

This error means you have not configured xdg variable . env | grep -i xdg

As I mentioned before, according to https://specifications.freedesktop.org/basedir-spec/latest/index.html#variables when the variable is not set, it should look up $HOME/.config as a fallback :)

Actually, I'm still thinking of fallbacks... the reason, to me it seems obvious it's the user responsibility to provide correct content into the API. When the fallback happened, it was not clear which config now is used

So, for now, fallback mechanic is not considered. And the new libcava version just fixed memory leaking

[OriginCode]

This error means you have not configured xdg variable . env | grep -i xdg

As I mentioned before, according to https://specifications.freedesktop.org/basedir-spec/latest/index.html#variables when the variable is not set, it should look up $HOME/.config as a fallback :)

Actually, I'm still thinking of fallbacks... the reason, to me it seems obvious it's the user responsibility to provide correct content into the API. When the fallback happened, it was not clear which config now is used

So, for now, fallback mechanic is not considered.

No pressure, at least $HOME works fine for now. I know it's weird to implement fallback for some environment variables. Just saying that XDG spec is followed and used widely by Linux distributions, it may be weird to users using the variable in the way the spec describes. Thank you for fixing the segfault ;)