Seg Fault with system-sleep script

[smoores-dev]

I'm on Ubuntu 22.10. I've added a script to send some CEC commands to /usr/lib/systemd/system-sleep/cec-control.sh:

#!/usr/bin/env bash

if [ "${1}" == "pre" ]; then
  /bin/echo "standby '0'" | /usr/bin/cec-client -s
fi

And I also have a hotkey set to :sleep.

When I hit the hotkey, for some reason Flex Launcher crashes with a Segmentation Fault. The script itself runs just fine, and I don't see anything in the Flex Launcher logs. But if I comment out the script, Flex Launcher doesn't crash.

I'm not sure how best to debug more, but please let me know if there's any other information I can provide!

[complexlogic]

How are you executing the script? Can you post the relevant part of your config file?

[smoores-dev]

The script is being executed by systemd just by virtue of being in that directory. The only relevant part of my config (at least, I think) is:

[Hotkeys]
Hotkey1=#40000065;:sleep

[smoores-dev]

More info about system-sleep if you're interested!

[smoores-dev]

I tried a few more things out just to have some more data points.

If I have a script like this:

# ~/.bin/suspend.sh
#!/usr/bin/env bash

/usr/bin/systemctl suspend

And leave the system-sleep script as above, and configure Flex Launcher with:

Hotkey1=#40000065;/home/<username>/.bin/suspend.sh

Flex Launcher also crashes.

If I instead include the cec command in the script itself (and remove the system-sleep script):

# ~/.bin/cec-suspend.sh
#!/usr/bin/env bash

/bin/echo 'standby 0' | /usr/bin/cec-client -s
/usr/bin/systemctl suspend

Hotkey1=#40000065;/home/<username>/.bin/cec-suspend.sh

Then I need to run flex-launcher as root (so that cec-client has the permissions it needs) ... and that also gets a crash.

It's weird because in all of these scenarios, the scripts all execute successfully (the cec-client turns off the TV and the computer is out to sleep), but then Flex Launcher gets a seg fault!

[complexlogic]

It would help you you could use gdb to trace the segfault, which may assist in diagnosis. Build Flex Launcher from source, but pass -DCMAKE_BUILD_TYPE=Debug during the CMake generation step which will retain the debug symbols in the executable. Then, execute the following:

1. gdb /path/to/flex-launcher
2. run -d
3. Reproduce the segfault
4. backtrace

Then post the output.

[smoores-dev]

Thread 1 "flex-launcher" received signal SIGSEGV, Segmentation fault.
0x00007ffff7cfcf48 in decoration_frame_configure (frame=0x5555556b58a0, configuration=0x555555ec6030, user_data=0x5555555e1ba0) at ./src/video/wayland/SDL_waylandwindow.c:782
782        ./src/video/wayland/SDL_waylandwindow.c: Directory not empty.
(gdb) backtrace
#0    0x00007ffff7cfcf48 in decoration_frame_configure
      (frame=0x5555556b58a0, configuration=0x555555ec6030, user_data=0x5555555e1ba0)  at ./src/video/wayland/SDL_waylandwindow.c:782
#1    0x00007ffff74027ec in xdg_surface_configure
      (user_data=0x5555556b58a0, xdg_surface=<optimized out>, serial=355)
#2    0x00007ffff6faae2e in ffi_call_unix64 () at ../src/x86/unix64.S:105
#3    0x00007ffff6fa7493 in ffi_call_int
      (cif=<optimized out>, fn=<optimized out>, rvalue=<optimized out>, avalue=<optimized out>, closure=<optimized out>) at ../src/x86/ffi64.c:672

[complexlogic]

Thanks. Looks like it's actually an issue in SDL, then. Could you try to run SDL_VIDEODRIVER=x11 flex-launcher and try to reproduce again? That will enable XWayland compatibility mode, which would confirm it's an issue with the SDL Wayland backend if the segfault can not be reproduced.

[smoores-dev]

Interestingly, I still see a seg fault (and still seemingly in SDL):

Thread 1 "flex-launcher" received signal SIGSEGV, Segmentation fault.
0x00007ffff7cfcf5c in SDL_IBus_UpdateTextRect (rect=0x5555555f3c370), at ./src/core/linux/SDL_ibus.c:667
667      ./src/core/linux/SDL_ibus.c: Directory not empty.
(gdb) backtrace
#0    0x00007ffff7cfcf5c in SDL_IBus_UpdateTextRect (rect=0x5555555f3c370 at ./src/core/linux/SDL_ibus.c:667
#1    0x00007ffff7dd1086 in SDL_IME_UpdateTextRect (rect=0x0) at ./src/core/linux/SDL_ime.c:142
#2    X11_DispatchEvent (_this=0x5555555abde0, _this@entry=<error reading variable: Cannot access memory at address 0x7fffffffdcb8, xevent=0x7fffffffdce0, xevent@entry=<error reading variable: Cannot access memory at address 0x7fffffffdca8)
      at ./src/video/x11/SDL_x11events.c:1169
#3    0x00007ffff7dd297b in X11_PumpEvents (_this=<error reading variable: Cannot access memory at address 0x7fffffffdcb8)
      at ./src/video/x11/SDL_x11events.c:1715
Backtrace stopped: Cannot access memory at address 0x7fffffffddd8