webkitgtk page crashes when missing gstreamer plugins

Hi Guix,

With core-updates-frozen commit e080e35dc1f012fa57a8e77759f933abdc3b8fc2

certain pages cause tabs to crash in webkitgtk browsers (I've tested with

epiphany, vimb, and luakit). The problem does not occur on current master,

0a9c946df9686f1610f7684492baabf0719c0164.

An example of a page the works:

An example of a page that doesn't work:

I was not able to notice a difference in messages when running the

browsers from a terminal between master and core-updates-frozen.

On both branches I do see "WebKit wasn't able to find a WebVTT encoder.

Not continuing without platform support for subtitles" when the tab

crashes, so I wonder if there is a gstreamer compatibility problem

(perhaps to do with libsoup versions). However, this could be a red

herring.

Best,

Jack

Hello!

Jack Hill <jackhill@jackhill.us> writes:

Would you be able to run it in GDB to gather a backtrace? That may

provide clues.

Thanks!

Maxim

On Wed, 8 Dec 2021, Maxim Cournoyer wrote:

Yes! I was albe to get the following backtrace. Thanks to hikiko [0]

for tips on using GDB with WebKit browsers

[0] https://eleni.mutantstargoat.com/hikiko/webkit-gdb/

$ gdb .midori-real 1979

GNU gdb (GDB) 11.1

Copyright (C) 2021 Free Software Foundation, Inc.

License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html

This is free software: you are free to change and redistribute it.

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Type "show copying" and "show warranty" for details.

This GDB was configured as "x86_64-unknown-linux-gnu".

Type "show configuration" for configuration details.

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For help, type "help".

Type "apropos word" to search for commands related to "word"...

Reading symbols from .midori-real...

(No debugging symbols found in .midori-real)

Attaching to program: /gnu/store/kz9inh53yvpzxv818jq6naiwp6ms85l0-midori-9.0/bin/.midori-real, process 1979

[New LWP 1981]

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[New LWP 1988]

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warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.

0x00007f70beab5d6f in poll () from /gnu/store/2fk1gz2s7ppdicynscra9b19byrrr866-glibc-2.33/lib/libc.so.6

(gdb) c

Continuing.

[New LWP 2395]

[New LWP 2411]

Thread 1 "WebKitWebProces" received signal SIGABRT, Aborted.

0x00007f70bea04030 in raise () from /gnu/store/2fk1gz2s7ppdicynscra9b19byrrr866-glibc-2.33/lib/libc.so.6

(gdb) bt

#0 0x00007f70bea04030 in raise () from /gnu/store/2fk1gz2s7ppdicynscra9b19byrrr866-glibc-2.33/lib/libc.so.6

#1 0x00007f70be9ee526 in abort () from /gnu/store/2fk1gz2s7ppdicynscra9b19byrrr866-glibc-2.33/lib/libc.so.6

#2 0x00007f70c4089a52 in WebCore::makeGStreamerElement(char const*, char const*) [clone .cold] () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#3 0x00007f70c63be439 in WebCore::MediaPlayerPrivateGStreamer::createVideoSink() () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#4 0x00007f70c63c351f in WebCore::MediaPlayerPrivateGStreamer::createGSTPlayBin(WTF::URL const&) () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#5 0x00007f70c63c442b in WebCore::MediaPlayerPrivateGStreamer::load(WTF::String const&) () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#6 0x00007f70c5c7e19c in WebCore::MediaPlayer::loadWithNextMediaEngine(WebCore::MediaPlayerFactory const*) () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#7 0x00007f70c5c7e76b in WebCore::MediaPlayer::load(WTF::URL const&, WebCore::ContentType const&, WTF::String const&) ()

from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#8 0x00007f70c570d73d in WebCore::HTMLMediaElement::loadResource(WTF::URL const&, WebCore::ContentType&, WTF::String const&) ()

from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#9 0x00007f70c570e3e1 in WebCore::HTMLMediaElement::loadNextSourceChild() () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#10 0x00007f70c54fc3c2 in WebCore::EventLoop::run() () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#11 0x00007f70c558a80d in WebCore::WindowEventLoop::didReachTimeToRun() () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#12 0x00007f70c5bdaadc in WebCore::ThreadTimers::sharedTimerFiredInternal() () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#13 0x00007f70c2a830f5 in WTF::RunLoop::TimerBase::TimerBase(WTF::RunLoop&)::{lambda(void*)#1}::_FUN(void*) ()

from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libjavascriptcoregtk-4.0.so.18

#14 0x00007f70c2a8333f in WTF::RunLoop::{lambda(_GSource*, int (*)(void*), void*)#1}::_FUN(_GSource*, int (*)(void*), void*) ()

from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libjavascriptcoregtk-4.0.so.18

#15 0x00007f70bef5236f in g_main_context_dispatch () from /gnu/store/qqs98rxwjrji6aaf6dqwp7q4m545g2sn-glib-2.70.0/lib/libglib-2.0.so.0

#16 0x00007f70bef526e8 in g_main_context_iterate.constprop () from /gnu/store/qqs98rxwjrji6aaf6dqwp7q4m545g2sn-glib-2.70.0/lib/libglib-2.0.so.0

#17 0x00007f70bef529cb in g_main_loop_run () from /gnu/store/qqs98rxwjrji6aaf6dqwp7q4m545g2sn-glib-2.70.0/lib/libglib-2.0.so.0

#18 0x00007f70c2a83470 in WTF::RunLoop::run() () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libjavascriptcoregtk-4.0.so.18

#19 0x00007f70c47e5c81 in WebKit::WebProcessMain(int, char**) () from /gnu/store/77vf3q1v7aa8h2av7s10fn95b0crh7zc-webkitgtk-with-libsoup2-2.34.1/lib/libwebkit2gtk-4.0.so.37

#20 0x00007f70be9ef7dd in __libc_start_main () from /gnu/store/2fk1gz2s7ppdicynscra9b19byrrr866-glibc-2.33/lib/libc.so.6

#21 0x000000000040107a in main ()

(gdb)

Dear guix,

As a guix home user on a GNOME guix system, both pages work in epiphany

(private mode) for me.

My graphics card is reported as "llvmpipe (LLVM 11.0.0, 256 bits)" by

GNOME.

Vivien

On Mon, 13 Dec 2021, Vivien Kraus via Bug reports for GNU Guix wrote:

Interesting, thank for reporting. What is your `guix describe` output?

I've successfully recreated the problem on Sway, GNOME Wayland, and GNOME

Xorg with

$ guix describe

Generation 47 Dec 15 2021 11:43:02 (current)

guix 2a621f1

repository URL: https://git.savannah.gnu.org/git/guix.git

branch: master

commit: 2a621f168faec09be7ed3f6b9351c24a472b19e4

Perhaps you have something else installed in your profile that I don't

that the WebKitGTK browsers need to work?

Is anyone else able to reproduce this issue?

Best,

Jack

I've attached the output of running `LD_DEBUG=all epiphany` and then

demonstrating the problem. Unfortunately, I wasn't able to determine what

part would be relevant, so I've attached the whole thing which is 1.3G

uncompressed.

Best,

Jack

I asked about this issue on #webkitgtk:gnome.org on IRC. It turns

out that what's missing from my environment is gst-plugins-bad (most

likely the fakevideosink plugin contained therein). If I install

gst-plugins-bad into an environment with a webgkitgtk browser, the crash I

was seeing is resolved. Only adding gst-plugins-bad to the inputs of

webkitgtk doesn't seem to be enough to solve the problem. I suppose some

additional wrapping is needed somewhere (although gst-plugins-base shows

up in the webkitgtk references).

What's the best path forward here?

Should leaf applications that use webkitgtk be wrapped to find the right

gst-plugins? This seems suboptimal to me. If the plugins are really

dependencies of webkitgtk then perhaps they should be encoded that way in

Guix.

Should webkitgtk be wrapped somehow to find the plugins on its own? How

would this wrapping be done? Do we want to force all webkitgtk applications

to carry around these dependencies?

Best,

Jack

Hello Jack,

Jack Hill <jackhill@jackhill.us> writes:

I think upstream should improve their software to display more

informative messages when a plugin is missing to play some content (a

tab crash is not very helpful!) :-).

I think there's not much to do here other than document the availability

of plugins to extend the capabilities of webkitgtk. It's won't be

obvious to leaf package users though, so fixing it upstream would still

have value.

As discussed on #guix, some reasons for not propagating them or even

wrapping them is the fact that they are *plugins*, that is, they exist

in that form so that users can compose them for runtime discovery as

they see fit. Propagating the plugins would go against this, and is not

very "Guixy" :-).

Another reason is that adding the gst-plugins-good and gst-plugins-bad

would inflate the size of the webkitgtk package by more than 1 GiB!

(compare "guix size webkitgtk" vs "guix size webkitgtk gst-plugins-good

gst-plugins-bad").

I'm tempted to make this change to the description of 'webkitgtk':

and close this as 'notabug'. What do you think?

Thanks,

Maxim

On Tue, 21 Dec 2021, Jack Hill wrote:

I got permission to quote from the IRC conversation for some additional

context:

10:52 < jackhill> Hi folks! In the Guix WebKitGTK packages we seem to have introduced a problem that causes tabs to crash on some

pages. I'm trying to track it down, but could use a hand in either identifying the solution or in more

troubleshooting techniques: https://issues.guix.gnu.org/52375

10:55 < MichaelCatanzaro[m]> jackhill: Looks like you're missing a GStreamer element that is required (do you have:

gst-plugins-base, gst-plugins-good, and at least the free half of gst-plugins-bad?)

10:56 < MichaelCatanzaro[m]> Alternatively, maybe try deleting ~/.cache/gstreamer-1.0 in the off chance your registry is corrupt

10:58 < MichaelCatanzaro[m]> jackhill: I think you're missing the fakevideosink element from gst-plugins-bad

11:01 < jackhill> MichaelCatanzaro[m]: thanks. Looking at our package definition we only depend directlyon gst-plugins-base. It

seems that we were scared off of -bad at some point in the past:

https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/webkit.scm#n255

11:03 < jackhill> I'll look into adding them (and manybe clearing my cache). Were we wrong in our assesment of -bad?

11:06 < MichaelCatanzaro[m]> jackhill: Yup, that is mandatory... and disabling GStreamerGL is not recommended either

11:06 < jackhill> MichaelCatanzaro[m]: yep, adding -bad did it! Is there an official WebKitGTK statement that I can point to when

proposing my fix to Guix?

11:06 < MichaelCatanzaro[m]> Not all the elements are mandatory, but some are...

11:07 < MichaelCatanzaro[m]> jackhill: No, we just expect you to have a working gstreamer installation

11:07 < jackhill> hehe, fair enough

11:08 < MichaelCatanzaro[m]> Looks like there is a bug report: https://bugs.webkit.org/show_bug.cgi?id=233949

[daychange]

10:55 < jackhill> MichaelCatanzaro[m]: we're having a conversation in #guix:libera.chat about adding the gst-plugins-bad. Can I

quote our conversation yesterday to hopefully bring others up to speed?

11:26 < MichaelCatanzaro[m]> <jackhill> "Michael Catanzaro: we're..." <- Of course, all the history here is public anyway

11:27 < MichaelCatanzaro[m]> You need: gst-plugins-base, gst-plugins-good, and gst-plugins-bad (not gst-plugins-ugly)

11:27 < MichaelCatanzaro[m]> gst-libav especially welcome if available, but not required...

11:29 < MichaelCatanzaro[m]> GStreamer is indeed used inside the bwrap sandbox (most applications do not enable the sandbox, but

Ephy does)

11:29 < MichaelCatanzaro[m]> All web content is handled sandboxed :)

We talked through some of these option on #guix:libera.chat (thanks

apteryx and cybersyn!) and it sounds like we're leaning towards the first

option. An additional concern with webkitgtk always pulling in the plugins

is that it increases the webkitgtk closure size by over 1G!

We're still waiting on webkitgtk builds to finish to help us determine if

we can enable GSTREAMER_GL.

Best,

Jack

retitle 52375 webkitgtk page crashes when missing gstreamer plugins

thanks

This problem isn't related to the core-updates-frozen work. I only noticed

it when testing then because I started with a clean profile that we

missing the plugins.

On Tue, Dec 21, 2021 at 11:39:05AM -0500, Maxim Cournoyer wrote:

If there is a particular plugin that is actually required for some

package, we could use the gst-plugins/selection procedure to add the

dependency while hopefully increasing the closure size by less than 1

GiB.

On Tue, 21 Dec 2021, Leo Famulari wrote:

Leo,

Thanks for pointing this out, it turned out to be very helpful!

Best,

Jack

On Tue, 21 Dec 2021, Maxim Cournoyer wrote:

Indeed. There actually is an upstream issue for this:

I think that this would good to add as a hint to WebKitGTK users. However,

I don't agree that it is notabug because I think browsers should work on

commonly encountered web content out of the box without asking folks to

track down the needed dependencies. I've opened a thread on

guix-devel@gnu.org to solicit more thoughts/discussion on how to best

address this issue: https://lists.gnu.org/archive/html/guix-devel/2021-12/msg00228.html

Thanks for helping think and work through this issue!

Jack