Phonon MMF: fixed crash during opening of video clip

A crash was observed during opening a video clip, and was traced
to dereferencing a null m_player pointer in
DsaVideoPlayer::handleParametersChanged(), which is called during
construction, but before createPlayer() has been called.

This was reproducible using the following sequence:
    1. Launch qmediaplayer
	2. Play an audio clip
	3. Open a video clip

However, the following sequence worked as expected:
    1. Launch qmediaplayer
	2. Play a video clip
	3. Play an audio clip
	4. Play a video clip
	...

It is not clear which commit introduced this defect.

Reviewed-by: Frans Englich

2 files changed, 58 insertions, 57 deletions

diff --git a/src/3rdparty/phonon/mmf/videoplayer_dsa.cpp b/src/3rdparty/phonon/mmf/videoplayer_dsa.cpp
index fbd8397..1925471 100644
--- a/src/3rdparty/phonon/mmf/videoplayer_dsa.cpp
+++ b/src/3rdparty/phonon/mmf/videoplayer_dsa.cpp
@@ -226,38 +226,40 @@ void MMF::DsaVideoPlayer::handleParametersChanged(VideoParameters parameters)
     getDsaRegion(m_wsSession, *m_window);
 #endif
 
-    static const TBool antialias = ETrue;
-    int err = KErrNone;
-
-    if (parameters & ScaleFactors) {
-        TRAP(err, m_player->SetScaleFactorL(m_scaleWidth, m_scaleHeight,
-                                            antialias));
-        if(KErrNone != err) {
-            TRACE("SetScaleFactorL (1) err %d", err);
-            setError(tr("Video display error"), err);
+    if (m_player) {
+        static const TBool antialias = ETrue;
+        int err = KErrNone;
+
+        if (parameters & ScaleFactors) {
+            TRAP(err, m_player->SetScaleFactorL(m_scaleWidth, m_scaleHeight,
+                                                antialias));
+            if(KErrNone != err) {
+                TRACE("SetScaleFactorL (1) err %d", err);
+                setError(tr("Video display error"), err);
+            }
         }
-    }
 
-    if (KErrNone == err) {
-        if (parameters & WindowHandle || parameters & WindowScreenRect) {
-            TRAP(err,
-                m_player->SetDisplayWindowL(m_wsSession, m_screenDevice,
-                                            *m_window,
-                                            m_videoScreenRect,
-                                            m_videoScreenRect));
-        }
+        if (KErrNone == err) {
+            if (parameters & WindowHandle || parameters & WindowScreenRect) {
+                TRAP(err,
+                    m_player->SetDisplayWindowL(m_wsSession, m_screenDevice,
+                                                *m_window,
+                                                m_videoScreenRect,
+                                                m_videoScreenRect));
+            }
 
-        if (KErrNone != err) {
-            TRACE("SetDisplayWindowL err %d", err);
-            setError(tr("Video display error"), err);
-        } else {
-            m_dsaActive = true;
-            if (parameters & ScaleFactors) {
-                TRAP(err, m_player->SetScaleFactorL(m_scaleWidth, m_scaleHeight,
-                                                    antialias));
-                if (KErrNone != err) {
-                    TRACE("SetScaleFactorL (2) err %d", err);
-                    setError(tr("Video display error"), err);
+            if (KErrNone != err) {
+                TRACE("SetDisplayWindowL err %d", err);
+                setError(tr("Video display error"), err);
+            } else {
+                m_dsaActive = true;
+                if (parameters & ScaleFactors) {
+                    TRAP(err, m_player->SetScaleFactorL(m_scaleWidth, m_scaleHeight,
+                                                        antialias));
+                    if (KErrNone != err) {
+                        TRACE("SetScaleFactorL (2) err %d", err);
+                        setError(tr("Video display error"), err);
+                    }
                 }
             }
         }
diff --git a/src/3rdparty/phonon/mmf/videoplayer_surface.cpp b/src/3rdparty/phonon/mmf/videoplayer_surface.cpp
index 5f234e5..fda7342 100644
--- a/src/3rdparty/phonon/mmf/videoplayer_surface.cpp
+++ b/src/3rdparty/phonon/mmf/videoplayer_surface.cpp
@@ -104,44 +104,43 @@ void MMF::SurfaceVideoPlayer::handleVideoWindowChanged()
 
 void MMF::SurfaceVideoPlayer::handleParametersChanged(VideoParameters parameters)
 {
-    CVideoPlayerUtility2 *player = static_cast<CVideoPlayerUtility2 *>(m_player.data());
-
-    int err = KErrNone;
-
     TRect rect;
-
     if (m_videoOutput) {
         m_videoOutput->dump();
         const QSize size = m_videoOutput->videoWindowSize();
         rect.SetSize(TSize(size.width(), size.height()));
     }
 
-    if (parameters & WindowHandle) {
-        if (m_displayWindow)
-            player->RemoveDisplayWindow(*m_displayWindow);
-
-        RWindow *window = static_cast<RWindow *>(m_window);
-        if (window) {
-            window->SetBackgroundColor(TRgb(0, 0, 0, 255));
-            TRAP(err, player->AddDisplayWindowL(m_wsSession, m_screenDevice, *window, rect, rect));
-            if (KErrNone != err) {
-                setError(tr("Video display error"), err);
-                window = 0;
+    CVideoPlayerUtility2 *player = static_cast<CVideoPlayerUtility2 *>(m_player.data());
+    if (player) {
+        int err = KErrNone;
+        if (parameters & WindowHandle) {
+            if (m_displayWindow)
+                player->RemoveDisplayWindow(*m_displayWindow);
+
+            RWindow *window = static_cast<RWindow *>(m_window);
+            if (window) {
+                window->SetBackgroundColor(TRgb(0, 0, 0, 255));
+                TRAP(err, player->AddDisplayWindowL(m_wsSession, m_screenDevice, *window, rect, rect));
+                if (KErrNone != err) {
+                    setError(tr("Video display error"), err);
+                    window = 0;
+                }
             }
+            m_displayWindow = window;
         }
-        m_displayWindow = window;
-    }
 
-    if (KErrNone == err) {
-        if (parameters & ScaleFactors) {
-            Q_ASSERT(m_displayWindow);
-            TRAP(err, player->SetVideoExtentL(*m_displayWindow, rect));
-            if (KErrNone == err)
-                TRAP(err, player->SetWindowClipRectL(*m_displayWindow, rect));
-            if (KErrNone == err)
-                TRAP(err, player->SetScaleFactorL(*m_displayWindow, m_scaleWidth, m_scaleHeight));
-            if (KErrNone != err)
-                setError(tr("Video display error"), err);
+        if (KErrNone == err) {
+            if (parameters & ScaleFactors) {
+                Q_ASSERT(m_displayWindow);
+                TRAP(err, player->SetVideoExtentL(*m_displayWindow, rect));
+                if (KErrNone == err)
+                    TRAP(err, player->SetWindowClipRectL(*m_displayWindow, rect));
+                if (KErrNone == err)
+                    TRAP(err, player->SetScaleFactorL(*m_displayWindow, m_scaleWidth, m_scaleHeight));
+                if (KErrNone != err)
+                    setError(tr("Video display error"), err);
+            }
         }
     }
 }