Bug 36142 – [Qt] MediaPlayerPrivate: don't crash when no media services can be found.

• Status: RESOLVED
• Resolution: FIXED
• Component: Media

[Jakub Wieczorek]

When no media services for QtMultimedia are installed, Qt outputs this to stderr:
defaultServiceProvider::requestService(): no service found for - "com.nokia.qt.mediaplayer",
and then in some situations QtWebKit would crash. In my case it was crashing in MediaPlayerPrivate::buffered(), with the following backtrace:

(gdb) frame 0
#0  0x00007ffff70db13b in WebCore::MediaPlayerPrivate::buffered (this=0xc16390) at ../../../WebCore/platform/graphics/qt/MediaPlayerPrivateQt.cpp:303
303         QMediaTimeRange playbackRanges = m_mediaPlayerControl->availablePlaybackRanges();
#1  0x00007ffff70cc4ed in WebCore::MediaPlayer::buffered (this=0xebc520) at ../../../WebCore/platform/graphics/MediaPlayer.cpp:455
No locals.
#2  0x00007ffff6ff1510 in WebCore::RenderThemeQt::paintMediaSliderTrack (this=0x810510, o=0x13627f8, paintInfo=..., r=...) at ../../../WebCore/platform/qt/RenderThemeQt.cpp:1118
        buffered = {m_ptr = 0x7fffffffb2c0}
        player = 0xebc520
        mediaElement = <value optimized out>
        p = {painter = 0x7fffffffc490, widget = 0x88dbb0, style = 0x7d6060, oldBrush = {d = {d = 0xd25d50}}, oldAntialiasing = true}

m_mediaPlayerControl is not null there, even though it should:

(gdb) print m_mediaPlayerControl
$1 = (class QMediaPlayerControl *) 0x1a400000088

[Jakub Wieczorek]

Created attachment 50745 [details]
Patch

[Eric Seidel (no email)]

Comment on attachment 50745 [details]
Patch

Test case?

[Jakub Wieczorek]

(In reply to comment #2)
> (From update of attachment 50745 [details])
> Test case?

The presence of the bug depends on the installed media backends so I am afraid this cannot be easily testable or at least the test would be much more complicated than the fix itself.

[Jakub Wieczorek]

Committed r56065: http://trac.webkit.org/changeset/56065