[webkit-gtk] Handling Plugins and Error scanning plugin

Carlos Garcia Campos cgarcia at igalia.com
Wed Jan 21 01:10:23 PST 2015 

El mié, 21-01-2015 a las 03:59 -0500, Nicolas Jäger escribió:
> hi,
> 
> > The GAsyncResult you're passing to 
> > webkit_web_context_get_plugins_finish() is uninitialized. It's passed 
> > as the second argument to your callback, so you should declare at
> > least that many parameters.
> ok, to be honnest, I don't really understand what do and from where come
> these asynchronous function. I'm just passing some pointers as you told
> me :
> 
> void
> callback( WebKitWebContext *web_context
>         , GAsyncResult *result
>         )
> {
>   GList *plugin_list, *p;
>   GError *error = nullptr;
> 
>   plugin_list = webkit_web_context_get_plugins_finish (web_context,
>   result, &error); if( error )
>   {
>     std::cout<< error->message << std::endl;
>     exit(1);
>   }
> 
> 
>   for (p = plugin_list; p; p = p->next)
>   {
>     WebKitPlugin *plugin = WEBKIT_PLUGIN (p->data);
>     std::cout << webkit_plugin_get_name (plugin) << std::endl;
>     g_object_unref(p->data);
>   }
> 
>   g_list_free(plugin_list);
> 
> }
> 
> > 
> > You should also pass a GError unless you're sure you want to silence 
> > errors. Something like this is typical:
>  done.
> 
> so now when I start the browser, I still have some error messages,
> 
> Error scanning
> plugin /usr/lib/mozilla/plugins/gecko-mediaplayer-dvx.so, /usr/lib/webkit2gtk-4.0/WebKitPluginProcess
> returned 256 exit status Error scanning
> plugin /usr/lib/mozilla/plugins/gecko-mediaplayer-qt.so, /usr/lib/webkit2gtk-4.0/WebKitPluginProcess
> returned 256 exit status Error scanning
> plugin /usr/lib/mozilla/plugins/gecko-mediaplayer-rm.so, /usr/lib/webkit2gtk-4.0/WebKitPluginProcess
> returned 256 exit status Error scanning
> plugin /usr/lib/mozilla/plugins/mozplugger.so, /usr/lib/webkit2gtk-4.0/WebKitPluginProcess
> returned 256 exit status

These errors are harmless, it's because the plugin scanner fails to get
plugin information from those .so, typically because they are not NPAPI
plugins.

>  but no more segmentation fault (I guess it was because of the nullptr).
>  I tested to go on several websites, I got no trouble except for one
> site : YOUTUBE. No prob with dailymotion, several broadcast news
> neither, just youtube!
> 
> there a copy of the errors :
> 
> 
> [BEGIN OF ERRORS]
> 
> (WebKitWebProcess:3600): GLib-GObject-WARNING **: invalid (NULL)
> pointer instance
> 
> (WebKitWebProcess:3600): GLib-GObject-CRITICAL **:
> g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)'
> failed 1
> 0xb4727ce3 /usr/lib/libjavascriptcoregtk-4.0.so.18(WTFCrash+0x23)
> [0xb4727ce3] 2
> 0xb473473b /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3WTF11fastReallocEPvj+0x1db)
> [0xb473473b] 3
> 0xb425acaf /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3JSC17BytecodeGenerator8generateEv+0x67f)
> [0xb425acaf] 4
> 0xb457a352 /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3JSC9CodeCache18getGlobalCodeBlockINS_24UnlinkedProgramCodeBlockENS_17ProgramExecutableEEEPT_RNS_2VMEPT0_RKNS_10SourceCodeENS_18JSParserStrictnessENS_12DebuggerModeENS_12ProfilerModeERNS_11ParserErrorE+0x5d2)
> [0xb457a352] 5
> 0xb4576e2f /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3JSC9CodeCache19getProgramCodeBlockERNS_2VMEPNS_17ProgramExecutableERKNS_10SourceCodeENS_18JSParserStrictnessENS_12DebuggerModeENS_12ProfilerModeERNS_11ParserErrorE+0x2f)
> [0xb4576e2f] 6
> 0xb45d9695 /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3JSC14JSGlobalObject22createProgramCodeBlockEPNS_9ExecStateEPNS_17ProgramExecutableEPPNS_8JSObjectE+0xf5)
> [0xb45d9695] 7
> 0xb45a91c8 /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3JSC17ProgramExecutable26initializeGlobalPropertiesERNS_2VMEPNS_9ExecStateEPNS_7JSScopeE+0x58)
> [0xb45a91c8] 8
> 0xb4453260 /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3JSC11Interpreter7exec
> 9
> 0xb458e23c /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3JSC8evaluateEPNS_9Exe
> 10  0xb5d34d78 /usr/lib/libwebkit2gtk-4.0.so.37(+0x55dd78) [0xb5d34d78]
> 11  0xb5d35045 /usr/lib/libwebkit2gtk-4.0.so.37(+0x55e045) [0xb5d35045]
> 12  0xb5f19564 /usr/lib/libwebkit2gtk-4.0.so.37(+0x742564) [0xb5f19564]
> 13  0xb5f19da0 /usr/lib/libwebkit2gtk-4.0.so.37(+0x742da0) [0xb5f19da0]
> 14  0xb5f1d046 /usr/lib/libwebkit2gtk-4.0.so.37(+0x746046) [0xb5f1d046]
> 15  0xb5f1db9b /usr/lib/libwebkit2gtk-4.0.so.37(+0x746b9b) [0xb5f1db9b]
> 16  0xb5f1da66 /usr/lib/libwebkit2gtk-4.0.so.37(+0x746a66) [0xb5f1da66]
> 17  0xb63a0fee /usr/lib/libwebkit2gtk-4.0.so.37(+0xbc9fee) [0xb63a0fee]
> 18  0xb63a1022 /usr/lib/libwebkit2gtk-4.0.so.37(+0xbca022) [0xb63a1022]
> 19  0xb676b31b /usr/lib/libwebkit2gtk-4.0.so.37(+0xf9431b) [0xb676b31b]
> 20
> 0xb477257f /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3WTF15GMainLoopSource1
> 21
> 0xb476e0af /usr/lib/libjavascriptcoregtk-4.0.so.18(_ZN3WTF15GMainLoopSource1
> 22  0xb476e0fc /usr/lib/libjavascriptcoregtk-4.0.so.18(+0x6a90fc)
> [0xb476e0fc] 23
> 0xb48ad8d3 /usr/lib/libglib-2.0.so.0(g_main_context_dispatch+0x153)
> [0xb48ad 24  0xb48adce9 /usr/lib/libglib-2.0.so.0(+0x46ce9)
> [0xb48adce9] 25
> 0xb48ae099 /usr/lib/libglib-2.0.so.0(g_main_loop_run+0xf9) [0xb48ae099]
> 26  0xb6f9f369 /usr/lib/libwebkit2gtk-4.0.so.37(+0x17c8369)
> [0xb6f9f369] 27
> 0xb5bd7a67 /usr/lib/libwebkit2gtk-4.0.so.37(WebProcessMainUnix+0x1d7)
> [0xb5b 28
> 0x80485c2 /usr/lib/webkit2gtk-4.0/WebKitWebProcess(main+0x32)
> [0x80485c2] 29  0xb5635e5e /usr/lib/libc.so.6(__libc_start_main+0xde)
> [0xb5635e5e] 30  0x80485ee /usr/lib/webkit2gtk-4.0/WebKitWebProcess()
> [0x80485ee]
> 
> [END OF ERRORS]
> 
> I really have no idea how to deal with that, as you can see there is no
> error from the callback function. I can see at the very first line a
> story about a null pointer, do I forget to set something ? I searched
> during several hours from now, but I don't have any begin of clue. 

The crash looks unrelated, since it's a WebProcess crash, or does it
only happen when you try to get the list of plugins?

> Then I wanted to switch the javascript plugins, since the word
> javascript appears several times in the errors. At this point I went
> here : 
> 
> https://wiki.gnome.org/Projects/WebKitGtk/ProgrammingGuide/Cookbook#Executing_JavaScript
> 
> this section of the website seems outdated, here is my code :
> 
>   WebKitWebView* webview;
>   WebKitSettings *settings;
>   webview =  WEBKIT_WEB_VIEW( webkit_web_view_new() );
>   settings = webkit_settings_new ();
>   std::cout << webkit_settings_get_enable_javascript(settings) <<
>   std::endl;
>   webkit_settings_set_enable_javascript(settings,false/*true*/);
>   webkit_web_view_set_settings ( webview, settings ); std::cout <<
>   webkit_settings_get_enable_javascript(settings) << std::endl;
> 
> now, when javascript is disabled, I can go without any error (even
> without those about scanning) on youtube, but of course youtube asks me
> to turn it on, and I have no video

What WebKitGTK+ version?

> regards,
> /nicoo
> _______________________________________________
> webkit-gtk mailing list
> webkit-gtk at lists.webkit.org
> https://lists.webkit.org/mailman/listinfo/webkit-gtk
> 

-- 
Carlos Garcia Campos
http://pgp.rediris.es:11371/pks/lookup?op=get&search=0xF3D322D0EC4582C3
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