[GTK] [2.28.0] The Yelp build crashes if DISPLAY is not set

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Alberto Garcia]

It seems that it's impossible to build Yelp (which links against WebKitGTK) if DISPLAY is unset:

Gtk-CRITICAL **: 18:22:42.130: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed
WARNING **: 18:22:42.132: Unable to connect to dbus: Cannot autolaunch D-Bus without X11 $DISPLAY
Unable to init server: Could not connect: Connection refused

I don't have a full backtrace with all symbols but this one already points at the problem:

Thread 1 "libyelp-scan" received signal SIGABRT, Aborted.
0x00007ffff7c56761 in raise () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff7c56761 in raise () at /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff7c4055b in abort () at /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff4ba02ed in  () at /usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37
#3  0x00007ffff507079b in WebKit::HardwareAccelerationManager::HardwareAccelerationManager() () at ../Source/WebKit/UIProcess/gtk/HardwareAccelerationManager.cpp:55
#4  0x00007ffff507081c in WTF::NeverDestroyed<WebKit::HardwareAccelerationManager>::NeverDestroyed<>() () at DerivedSources/ForwardingHeaders/wtf/NeverDestroyed.h:52
#5  WebKit::HardwareAccelerationManager::singleton() () at ../Source/WebKit/UIProcess/gtk/HardwareAccelerationManager.cpp:36
#6  0x00007ffff50786d9 in WebKit::WebPreferences::platformInitializeStore() () at ../Source/WebKit/UIProcess/gtk/WebPreferencesGtk.cpp:42
#7  0x00007ffff4eea222 in WebKit::WebPreferences::create(WTF::String const&, WTF::String const&, WTF::String const&) () at ../Source/WebKit/UIProcess/WebPreferences.cpp:45
#8  0x00007ffff4fbb101 in _WebKitSettingsPrivate::_WebKitSettingsPrivate() () at ../Source/WebKit/UIProcess/API/glib/WebKitSettings.cpp:59
#9  0x00007ffff7fa8e6d in g_type_create_instance () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#10 0x00007ffff7f886dd in  () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#11 0x00007ffff7f8a5e9 in g_object_new_valist () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#12 0x00007ffff4fb5588 in webkit_settings_new_with_settings() () at ../Source/WebKit/UIProcess/API/glib/WebKitSettings.cpp:1577
#13 0x00007ffff7e32726 in yelp_view_get_global_settings () at libyelp/yelp-view.c:153
#14 0x00007ffff7e3274d in settings_show_text_cursor (settings=settings@entry=0x5555555b8150) at libyelp/yelp-view.c:2094
#15 0x00007ffff7e327e3 in yelp_view_class_init (klass=0x5555555b6520) at libyelp/yelp-view.c:465
#16 yelp_view_class_intern_init (klass=0x5555555b6520) at libyelp/yelp-view.c:144
#17 0x00007ffff7fa6ef1 in g_type_class_ref () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#18 0x00005555555565bc in get_object_types () at libyelp-scan.c:62
#19 main () at libyelp-scan.c:113

That's here:

    if (!AcceleratedBackingStore::checkRequirements()) {
        m_canUseHardwareAcceleration = false;
        return;
    }

See also bug 156972 for a related problem already fixed 4 years ago.

[Alberto Garcia]

Ok, so we're hitting the RELEASE_ASSERT_NOT_REACHED() in
AcceleratedBackingStore::checkRequirements(), and the reason is that
the PlatformDisplay type is neither Wayland nor X11, but WPE.

[Carlos Garcia Campos]

(In reply to Alberto Garcia from comment #1)
> Ok, so we're hitting the RELEASE_ASSERT_NOT_REACHED() in
> AcceleratedBackingStore::checkRequirements(), and the reason is that
> the PlatformDisplay type is neither Wayland nor X11, but WPE.

I think we can just remove that assert

[Carlos Garcia Campos]

Created attachment 395152 [details]
Patch

[Carlos Garcia Campos]

Committed r259380: <https://trac.webkit.org/changeset/259380>

[Alberto Garcia]

It looks like the Yelp build still crashes, different backtrace this time:

(process:35799): Gtk-CRITICAL **: 13:40:20.270: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed

** (process:35799): WARNING **: 13:40:20.271: Unable to connect to dbus: Cannot autolaunch D-Bus without X11 $DISPLAY
Unable to init server: Could not connect: Connection refused
Segmentation fault

Thread 1 "libyelp-scan" received signal SIGSEGV, Segmentation fault.
0x00007ffff335cbd4 in wpe_renderer_backend_egl_destroy (backend=0x0) at ./src/renderer-backend-egl.c:54
54          backend->base.interface->destroy(backend->base.interface_data);
(gdb) bt
#0  0x00007ffff335cbd4 in wpe_renderer_backend_egl_destroy (backend=0x0) at ./src/renderer-backend-egl.c:54
#1  0x00007ffff63bc8bb in WebCore::PlatformDisplayLibWPE::~PlatformDisplayLibWPE() ()
    at ../Source/WebCore/platform/graphics/libwpe/PlatformDisplayLibWPE.cpp:66
#2  0x00007ffff63bc8d9 in WebCore::PlatformDisplayLibWPE::~PlatformDisplayLibWPE() ()
    at ../Source/WebCore/platform/graphics/libwpe/PlatformDisplayLibWPE.cpp:67
#3  0x00007ffff7c59e27 in __run_exit_handlers
    (status=0, listp=0x7ffff7dd8718 <__exit_funcs>, run_list_atexit=run_list_atexit@entry=true, run_dtors=run_dtors@entry=true)
    at exit.c:108
#4  0x00007ffff7c59fda in __GI_exit (status=<optimized out>) at exit.c:139
#5  0x00007ffff7c42e12 in __libc_start_main (main=
    0x555555556480 <main>, argc=1, argv=0x7fffffffdd78, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffdd68) at ../csu/libc-start.c:342
#6  0x0000555555557b7a in _start () at libyelp-scan.c:1025

So it seems that m_backend is null in the PlatformDisplayLibWPE destructor.

[Alberto Garcia]

I confirm that checking for null in wpe_renderer_backend_egl_destroy() is enough to avoid the crash and fix the Yelp build, but perhaps the change should be in WebKit ?

[Carlos Garcia Campos]

I don't think we should create a PlatformDisplayLibWPE as fallback. We could fix it in PlatformDisplay::createPlatformDisplay()

either:

#if USE(WPE_RENDERER) -> #if USE(LIBWPE)

or just move the block:

#if USE(WPE_RENDERER)
    return PlatformDisplayLibWPE::create();
#elif PLATFORM(WIN)
    return PlatformDisplayWin::create();
#endif

at the end of the function, right before the RELEASE_ASSERT_NOT_REACHED()

Could you try any of these solutions, please?

[Alberto Garcia]

(In reply to Carlos Garcia Campos from comment #7)
> or just move the block:
> 
> #if USE(WPE_RENDERER)
>     return PlatformDisplayLibWPE::create();
> #elif PLATFORM(WIN)
>     return PlatformDisplayWin::create();
> #endif
> 
> at the end of the function, right before the RELEASE_ASSERT_NOT_REACHED()

I confirm that this one works and fixes the problem.

Do you want me to try the other one, or to prepare a patch with this one, or what?

[Carlos Garcia Campos]

Yes, please, just submit a patch with any of the solutions if you don't mind :-)

[Alberto Garcia]

Created attachment 397668 [details]
Patch

[Alberto Garcia]

Committed r260750: <https://trac.webkit.org/changeset/260750>