Crashes Xwayland in xwl_dmabuf_feedback_main_device on FreeBSD

[jbeich]

Predates epoch-1.0.0-alpha.1. Affects rootless, satellite and rootful Xwayland. Likely caused by Rust fossilizing 4-byte dev_t when FreeBSD >= 12 uses 8 bytes outside of backward compat (binaries built against old headers).

Note, Xwayland in niri (satellite and rootful) works fine despite also using Smithay. See also russelltg/wl-screenrec#99

$ HOME=$(mktemp -dt home) cosmic-comp
 WARN cosmic_comp::logger: Failed to init journald logging. err=Os { code: 2, kind: NotFound, message: "No such file or directory" }
ERROR i18n_embed::requester: Unable to parse your locale: ParserError(InvalidLanguage)
ERROR cosmic_comp::config: Failed to read config 'workspaces' err=NoConfigDirectory
ERROR cosmic_settings_config::shortcuts: failed to read system shortcuts config 'system_actions': GetKey("system_actions", Os { code: 2, kind: NotFound, message: "No such file or directory" })
ERROR cosmic_settings_config::shortcuts: failed to read local shortcuts config 'system_actions': NoConfigDirectory
ERROR cosmic_settings_config::shortcuts: shortcuts defaults config error: GetKey("defaults", Os { code: 21, kind: IsADirectory, message: "Is a directory" })
ERROR cosmic_settings_config::shortcuts: shortcuts custom config error: GetKey("custom", Os { code: 2, kind: NotFound, message: "No such file or directory" })
ERROR cosmic_settings_config::window_rules: tiling exceptions defaults config error: GetKey("tiling_exception_defaults", Os { code: 21, kind: IsADirectory, message: "Is a directory" })
ERROR cosmic_settings_config::window_rules: tiling exceptions custom config error: GetKey("tiling_exception_custom", Os { code: 2, kind: NotFound, message: "No such file or directory" })
ERROR smithay::xwayland::xserver: Xwayland terminated: signal: 6 (SIGABRT)
^C

$ lldb --core Xwayland.1234.core Xwayland
(lldb) bt
* thread #1, name = 'Xwayland', stop reason = signal SIGABRT
  * frame #0: 0x00000008303fd82a libsys.so.7`__sys_thr_kill at thr_kill.S:4
    frame #1: 0x000000082d646074 libc.so.7`__raise(s=6) at raise.c:48:10
    frame #2: 0x000000082d708879 libc.so.7`abort at abort.c:61:8
    frame #3: 0x000000000046888a Xwayland`OsAbort at utils.c:1283:5
    frame #4: 0x000000000046f215 Xwayland`AbortServer at log.c:892:9
    frame #5: 0x000000000046f0cd Xwayland`FatalError(f="") at log.c:1030:9
    frame #6: 0x000000000046581e Xwayland`OsSigHandler(signo=6, sip=0x00000008205f1970, unused=0x00000008205f1600) at osinit.c:156:5
    frame #7: 0x000000082ad71aad libthr.so.3`handle_signal(actp=0x00000008205f1580, sig=6, info=0x00000008205f1970, ucp=0x00000008205f1600) at thr_sig.c:297:3
    frame #8: 0x000000082ad70f8a libthr.so.3`thr_sighandler(sig=6, info=0x00000008205f1970, _ucp=0x00000008205f1600) at thr_sig.c:243:2
    frame #9: 0x00000008214052d3
    frame #10: 0x000000082d708879 libc.so.7`abort at abort.c:61:8
    frame #11: 0x000000082d628831 libc.so.7`__assert(func=<unavailable>, file=<unavailable>, line=<unavailable>, failedexpr=<unavailable>) at assert.c:47:2
    frame #12: 0x00000000002a6424 Xwayland`xwl_dmabuf_feedback_main_device(data=0x000007c4fd2c14b0, dmabuf_feedback=0x000007c4fd210860, dev=0x000007c4fd35fcd0) at xwayland-dmabuf.c:475:5
    frame #13: 0x000000082f8c3a92 libffi.so.8`ffi_call_unix64 at unix64.S:104
    frame #14: 0x000000082f8c2ec0 libffi.so.8`ffi_call_int(cif=0x00000008205f1ef0, fn=(Xwayland`xwl_dmabuf_feedback_main_device at xwayland-dmabuf.c:469), rvalue=0x0000000000000000, avalue=0x00000008205f1f20, closure=0x0000000000000000) at ffi64.c:673:3
    frame #15: 0x000000082f8c2a8c libffi.so.8`ffi_call(cif=0x00000008205f1ef0, fn=(Xwayland`xwl_dmabuf_feedback_main_device at xwayland-dmabuf.c:469), rvalue=0x0000000000000000, avalue=0x00000008205f1f20) at ffi64.c:710:3
    frame #16: 0x00000008250af044 libwayland-client.so.0`wl_closure_invoke(closure=0x000007c4fd35fc00, flags=1, target=0x000007c4fd210860, opcode=2, data=0x000007c4fd2c14b0) at connection.c:1228:2
    frame #17: 0x00000008250ac994 libwayland-client.so.0`dispatch_event(display=0x000007c4fd23e280, queue=0x000007c4fd23e378) at wayland-client.c:1674:3
    frame #18: 0x00000008250ab8f5 libwayland-client.so.0`dispatch_queue(display=0x000007c4fd23e280, queue=0x000007c4fd23e378) at wayland-client.c:1820:3
    frame #19: 0x00000008250ab6fd libwayland-client.so.0`wl_display_dispatch_queue_pending(display=0x000007c4fd23e280, queue=0x000007c4fd23e378) at wayland-client.c:2062:8
    frame #20: 0x00000008250ab309 libwayland-client.so.0`wl_display_dispatch_queue(display=0x000007c4fd23e280, queue=0x000007c4fd23e378) at wayland-client.c:2038:9
    frame #21: 0x00000008250aaeee libwayland-client.so.0`wl_display_roundtrip_queue(display=0x000007c4fd23e280, queue=0x000007c4fd23e378) at wayland-client.c:1448:9
    frame #22: 0x00000008250ab360 libwayland-client.so.0`wl_display_roundtrip(display=0x000007c4fd23e280) at wayland-client.c:1477:9
    frame #23: 0x0000000000297ebc Xwayland`xwl_screen_roundtrip(xwl_screen=0x000007c4fd2c1300) at xwayland-screen.c:731:15
    frame #24: 0x00000000002987ca Xwayland`xwl_screen_init(pScreen=0x000007c4fd2c4000, argc=11, argv=0x00000008205f2448) at xwayland-screen.c:1027:5
    frame #25: 0x000000000032ca7a Xwayland`AddScreen(pfnInit=(Xwayland`xwl_screen_init at xwayland-screen.c:856), argc=11, argv=0x00000008205f2448) at dispatch.c:3993:10
    frame #26: 0x0000000000288c99 Xwayland`InitOutput(screen_info=0x00000000004ff540, argc=11, argv=0x00000008205f2448) at xwayland.c:455:9
    frame #27: 0x00000000003329a5 Xwayland`dix_main(argc=11, argv=0x00000008205f2448, envp=0x00000008205f24a8) at main.c:193:9
    frame #28: 0x00000000002abeea Xwayland`main(argc=11, argv=0x00000008205f2448, envp=0x00000008205f24a8) at stubmain.c:34:12
    frame #29: 0x000000082d618325 libc.so.7`__libc_start1(argc=<unavailable>, argv=0x00000008205f2448, env=<unavailable>, cleanup=<unavailable>, mainX=(Xwayland`main at stubmain.c:33)) at libc_start1.c:172:7
    frame #30: 0x0000000000288110 Xwayland`_start at crt1_s.S:83
(lldb) f 12
frame #12: 0x00000000002a6424 Xwayland`xwl_dmabuf_feedback_main_device(data=0x000007c4fd2c14b0, dmabuf_feedback=0x000007c4fd210860, dev=0x000007c4fd35fcd0) at xwayland-dmabuf.c:475:5
   472
   473      xwl_check_reset_tranche_info(xwl_feedback);
   474
-> 475      assert(dev->size == sizeof(dev_t));
            ^
   476      memcpy(&devid, dev->data, sizeof(dev_t));
   477
   478      drmFreeDevice(&xwl_feedback->main_dev);
(lldb) p dev->size
(size_t) 4
(lldb) p sizeof(dev_t)
(unsigned long) 8

[ids1024]

Hm, I don't recall seeing this when I tested on FreeBSD, but its been a while now.

In smithay-client-toolkit, I added a workaround for dev_t on FreeBSD: https://github.com/Smithay/client-toolkit/blob/25079ae75cb6952b0542aa343bd5a52c81d135d4/src/dmabuf.rs#L15-L19

I guess smithay may need something similar.