Segfault without debug message when XKB_DEFAULT_LAYOUT is not correct

[louwenus]

Please fill out the following:

• Sway Version:
  sway version 1.9-dev-4326a26a (Oct 22 2023, branch 'makepkg')
  (also reproducible with latest arch package)

• Debug Log:
  debug_log

• Configuration File:
  Default (/etc/sway/config)

• Stack Trace:

  #0  0x00007ff58eac8b60 in xkb_keymap_ref () at /usr/lib/libxkbcommon.so.0
  #1  0x00007ff58eace3c5 in xkb_state_new () at /usr/lib/libxkbcommon.so.0
  #2  0x0000560db9ad3e0e in  ()
  #3  0x0000560db9ac9549 in  ()
  #4  0x00007ff58e8b0cd0 in  () at /usr/lib/libc.so.6
  #5  0x00007ff58e8b0d8a in __libc_start_main () at /usr/lib/libc.so.6
  #6  0x0000560db9aca0f5 in  ()
  

• Description:
  Set XKB_DEFAULT_LAYOUT to a layout you do not have (fr-latin9 in my case)
  Run sway
  Sway segfault (SIGSEGV and return 139)

  I would have expected sway to launch anyway, using default keyboard and/or output a helpful message about what went wrong

Upon trying to understand this issue, I used sway -Vd in order to understand what was happening:
When doing so from a terminal emulator (eg, a started sway or X session), we get full debug (just like when using sway -d 2>sway.log)
However, when the command is issued directly from TTY, a lot of output is missing (including the obvious last lines pointing at what the error was), only 26 lines were printed, the last one being 00:00:00.003 [DEBUG] [sway/server.c:89] Initializing Wayland server

This behavior is quite confusing, and do not seem documented (neither in the wiki nor the man pages), is it a bug?

NB: This bug seem to involve wlroots/libxkbcommon, and I did not know to who I should report it. If you think this bug report should be redirected to one or the other, please feel free to redirect me there.

[abextm]

Here is a symbolicated stack from sway 1.9 release on arch

#0  xkb_keymap_ref (keymap=0x0) at ../libxkbcommon/src/keymap.c:61
#1  0x00007a8bc53913c5 in xkb_state_new (keymap=keymap@entry=0x0) at ../libxkbcommon/src/state.c:594
#2  0x00006514808d1dfe in keysym_translation_state_create (rules=...) at ../sway-1.9/sway/config.c:47
#3  config_defaults (config=<optimized out>) at ../sway-1.9/sway/config.c:340
#4  load_main_config (file=<optimized out>, is_active=false, validating=false)
    at ../sway-1.9/sway/config.c:465
#5  0x00006514808c7572 in main (argc=<optimized out>, argv=0x7ffda0830cc8)
    at ../sway-1.9/sway/main.c:393

and some log lines for googlability

xkbcommon: DEBUG: Compiling xkb_symbols "(unnamed)"
xkbcommon: ERROR: [XKB-338] Couldn't find file "symbols/dvorak" in include paths
xkbcommon: ERROR: [XKB-338] 1 include paths searched:
xkbcommon: ERROR: [XKB-338]     /usr/share/X11/xkb
xkbcommon: ERROR: [XKB-338] 3 include paths could not be added:
xkbcommon: ERROR: [XKB-338]     /home/abex/.config/xkb
xkbcommon: ERROR: [XKB-338]     /home/abex/.xkb
xkbcommon: ERROR: [XKB-338]     /etc/xkb
xkbcommon: ERROR: [XKB-769] Abandoning symbols file "(unnamed)"
xkbcommon: ERROR: Failed to compile xkb_symbols
xkbcommon: ERROR: Failed to compile keymap

[emersion]

when the command is issued directly from TTY, a lot of output is missing (including the obvious last lines pointing at what the error was), only 26 lines were printed, the last one being 00:00:00.003 [DEBUG] [sway/server.c:89] Initializing Wayland server

It's the kernel console behavior, out of Sway's control.

Nevertheless, crashing is always a bug.

[emersion]

#8037 should help.