flutter-wayland segfaults

[jwinarske]

Reported as issue on i.MX target

bash-5.0# gdb --args flutter_wayland /usr/share/flutter-gallery/sony/data/flutter_assets/
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Reading symbols from flutter_wayland...
Reading symbols from /usr/bin/.debug/flutter_wayland...
(gdb) run
Starting program: /usr/bin/flutter_wayland /usr/share/flutter-gallery/sony/data/flutter_assets/
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
LOG: /usr/src/debug/flutter-wayland/git-r0/git/src/main.cc:65: Arg: /usr/share/flutter-gallery/sony/data/flutter_assets/

Program received signal SIGSEGV, Segmentation fault.
std::function<void (wayland::seat_capability)>::swap(std::function<void (wayland::seat_capability)>&) (__x=..., this=0xffffffffeee8)
    at /usr/include/c++/10.2.0/bits/std_function.h:483
483             std::swap(_M_functor, __x._M_functor);
(gdb) bt
#0  std::function<void (wayland::seat_capability)>::swap(std::function<void (wayland::seat_capability)>&) (__x=...,
    this=0xffffffffeee8) at /usr/include/c++/10.2.0/bits/std_function.h:483
#1  std::function<void(wayland::seat_capability)>::operator=<flutter::WaylandDisplay::WaylandDisplay(size_t, size_t, const std::vector<std::__cxx11::basic_string<char> >&)::<lambda(wayland::seat_capability)> > (__f=..., __f=..., this=0x8)
    at /usr/include/c++/10.2.0/bits/std_function.h:459
#2  flutter::WaylandDisplay::WaylandDisplay (this=0xffffffffefd0, width=<optimized out>, height=<optimized out>, args=...)
    at /usr/src/debug/flutter-wayland/git-r0/git/src/wayland_display.cc:196
#3  0x0000aaaaaaabce04 in flutter::Main (args=...) at /usr/src/debug/flutter-wayland/git-r0/git/src/main.cc:68
#4  0x0000aaaaaaaa59e0 in main (argc=<optimized out>, argv=<optimized out>) at /usr/include/c++/10.2.0/bits/stl_vector.h:102
(gdb)

[xobs]

These are fixed in https://github.com/jwinarske/flutter_wayland/pull/2

I am now able to run flutter_wayland:

bash-5.0# /home/user/flutter_wayland /usr/share/flutter-gallery/sony/data/flutter_assets/
LOG: /opt/Ion/yocto/imx-yocto-bsp/mek-build/tmp/work/cortexa35-mx8-poky-linux/flutter-wayland/git-r0/git/src/main.cc:65: Arg: /usr/share/flutter-gallery/sony/data/flutter_assets/
No seat management present
assets_path: /usr/share/flutter-gallery/sony/data/flutter_assets/
load_aot: 0
flutter: Observatory listening on http://127.0.0.1:44279/aKHoxCMuDic=/

However, nothing appears on the screen. Additionally, I have not yet found a way to make the "Flutter observatory" listen on 0.0.0.0.

[xobs]

Note that https://github.com/jwinarske/flutter_wayland/pull/2/commits/ccbca333c1a9a205bbd108d2a4d94b987e0cc756 may be unnecessary, and was caused by missing files in /run. I now have libinput working, however I still do not have any windows appearing. Even so, I feel that it is important to retain the check, in case it is run on a system that has no inputs or seat management.

At least it's not segfaulting! And many threads are running. But no window.

(gdb) run
Starting program: /home/user/flutter_wayland /usr/share/flutter-gallery/sony/data/flutter_assets/
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
LOG: /opt/Ion/yocto/imx-yocto-bsp/mek-build/tmp/work/cortexa35-mx8-poky-linux/flutter-wayland/git-r0/git/src/main.cc:65: Arg: /usr/share/flutter-gallery/sony/data/flutter_assets/
xdg_wm_base exists
Pointer Present
Keyboard Present
[New Thread 0xfffff250e100 (LWP 1086)]
[New Thread 0xfffff1d0d100 (LWP 1087)]
assets_path: /usr/share/flutter-gallery/sony/data/flutter_assets/
load_aot: 0
[New Thread 0xfffff1155100 (LWP 1088)]
[New Thread 0xfffff0954100 (LWP 1089)]
[New Thread 0xffffe3fff100 (LWP 1090)]
[New Thread 0xffffe2e51100 (LWP 1091)]
[New Thread 0xffffe2650100 (LWP 1092)]
[New Thread 0xfffff0153100 (LWP 1093)]
[New Thread 0xffffe19ff100 (LWP 1094)]
[New Thread 0xffffe12ff100 (LWP 1095)]
[New Thread 0xffffe11fe100 (LWP 1096)]
[New Thread 0xffffd257f100 (LWP 1097)]
flutter: Observatory listening on http://127.0.0.1:32837/7icHMNV8Qps=/
[New Thread 0xffffb6a7f100 (LWP 1098)]
[New Thread 0xffffaa67f100 (LWP 1099)]
[Thread 0xffffaa67f100 (LWP 1099) exited]
[Thread 0xffffe19ff100 (LWP 1094) exited]
[Thread 0xffffe12ff100 (LWP 1095) exited]
[Thread 0xffffb6a7f100 (LWP 1098) exited]
[Thread 0xffffd257f100 (LWP 1097) exited]
[New Thread 0xffffe19ff100 (LWP 1102)]
[Thread 0xffffe19ff100 (LWP 1102) exited]
[New Thread 0xffffd257f100 (LWP 1103)]
[Thread 0xffffd257f100 (LWP 1103) exited]

[xobs]

I managed to get https://github.com/NilsBrause/waylandpp/blob/master/example/egl.cpp to compile and run. Furthermore, I can access the Dart VM from inside flutter_wayland, so I know it's running.

I still don't have a window with flutter_wayland. I will continue looking into why flutter_wayland isn't displaying anything.

[xobs]

I can verify that the fixes in https://github.com/jwinarske/flutter_wayland/pull/2/commits work. The issue is that /usr/share/flutter-gallery/sony/data/flutter_assets/ doesn't actually draw anything, so it never ended up displaying anything on the screen.

After switching to another Flutter program, it's working with those patches.

[jwinarske]

Pretty sure the issue is the waylandpp call that checks for input is blocking, thereby blocking the engine task loop unless there is activity. So once it gets something (touch/mouse/keyboard) it renders. I ended up rewriting the embedder without waylandpp for Toyota last year. I'll look at fixing the blocking issue.

I rolled the commit to pick up your changes.

Thanks again!

[jwinarske]

Closing since the segfault is resolved.