Bug 35798 – Crash due to infinite recursion when viewing composited video on Windows

• Status: RESOLVED
• Resolution: FIXED
• Component: Layout and Rendering

[Chris Marrin]

Playing any video on Windows with HW compositing enabled will crash due to infinite recursion. Here's the top of the stack:

 	WebKit.dll!WebCore::MediaPlayerPrivate::notifySyncRequired(const WebCore::GraphicsLayer * __formal=0x0b955bd0)  Line 866 + 0xb bytes	C++
 	WebKit.dll!WebCore::GraphicsLayerCACF::notifySyncRequired()  Line 94 + 0x31 bytes	C++
 	WebKit.dll!WebCore::MediaPlayerPrivate::notifySyncRequired(const WebCore::GraphicsLayer * __formal=0x0b955bd0)  Line 869	C++
 	WebKit.dll!WebCore::GraphicsLayerCACF::notifySyncRequired()  Line 94 + 0x31 bytes	C++
 	WebKit.dll!WebCore::MediaPlayerPrivate::notifySyncRequired(const WebCore::GraphicsLayer * __formal=0x0b955bd0)  Line 869	C++

Proposed solution:
1. Make WKCACFLayer be a base class, with a virtual drawInContext() method
2. Subclass WKCACFLayer for GraphicsLayer (equivalent of WebLayer)
3. Subclass WKCACFLayer for the root, to allow the root layer to communicate with the WKCACFLayerRenderer.
4. Eliminate the notifySyncRequired callbacks.

[Chris Marrin]

Created attachment 50109 [details]
Patch

[WebKit Review Bot]

Attachment 50109 [details] did not pass style-queue:

Failed to run "WebKitTools/Scripts/check-webkit-style" exit_code: 1
WebCore/platform/graphics/win/GraphicsLayerCACF.cpp:120:  Weird number of spaces at line-start.  Are you using a 4-space indent?  [whitespace/indent] [3]
Total errors found: 1 in 13 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Simon Fraser (smfr)]

Comment on attachment 50109 [details]
Patch

> Index: WebCore/platform/graphics/win/GraphicsLayerCACF.cpp
> ===================================================================

> +class WebLayer : public WKCACFLayer {

> +private:
> +   GraphicsLayerCACF* m_owner;
> +};

Could WebLayer get away with having pointer to the base class (GraphicsLayer?). No point making it too incestuous with GraphicsLayerCACF if you can avoid it.

This this a great improvement to these classes!

[Simon Fraser (smfr)]

<rdar://problem/7706319>

[Chris Marrin]

Fixed in http://trac.webkit.org/changeset/55592