Fix some coverity null pointer dereference issues

src/app/composer/qgscomposertablebackgroundcolorsdialog.cpp

@@ -113,10 +113,13 @@ void QgsComposerTableBackgroundColorsDialog::setGuiElementValues()
   Q_FOREACH ( QgsComposerTableV2::CellStyleGroup styleGroup, mCheckBoxMap.keys() )
   {
     mCheckBoxMap.value( styleGroup )->setChecked( mComposerTable->cellStyle( styleGroup )->enabled );
-    mColorButtonMap.value( styleGroup )->setEnabled( mComposerTable->cellStyle( styleGroup )->enabled );
+    QgsColorButton* button = mColorButtonMap.value( styleGroup );
-    mColorButtonMap.value( styleGroup )->setColor( mComposerTable->cellStyle( styleGroup )->cellBackgroundColor );
+    if ( !button )
-    mColorButtonMap.value( styleGroup )->setAllowAlpha( true );
+      continue;
-    mColorButtonMap.value( styleGroup )->setColorDialogTitle( tr( "Select background color" ) );
+    button->setEnabled( mComposerTable->cellStyle( styleGroup )->enabled );
+    button->setColor( mComposerTable->cellStyle( styleGroup )->cellBackgroundColor );
+    button->setAllowAlpha( true );
+    button->setColorDialogTitle( tr( "Select background color" ) );
   }
 
   mDefaultColorButton->setColor( mComposerTable->backgroundColor() );

src/core/composer/qgscomposertablev2.cpp

@@ -231,7 +231,9 @@ bool QgsComposerTableV2::readXml( const QDomElement &itemElem, const QDomDocumen
       if ( !styleList.isEmpty() )
       {
         QDomElement styleElem = styleList.at( 0 ).toElement();
-        mCellStyles.value( it.key() )->readXml( styleElem );
+        QgsComposerTableStyle* style = mCellStyles.value( it.key() );
+        if ( style )
+          style->readXml( styleElem );
       }
     }
   }
@@ -1225,24 +1227,33 @@ QString QgsComposerTableV2::wrappedText( const QString &value, double columnWidt
 QColor QgsComposerTableV2::backgroundColor( int row, int column ) const
 {
   QColor color = mBackgroundColor;
-  if ( mCellStyles.value( OddColumns )->enabled && column % 2 == 0 )
+  if ( QgsComposerTableStyle* style = mCellStyles.value( OddColumns ) )
-    color = mCellStyles.value( OddColumns )->cellBackgroundColor;
+    if ( style->enabled && column % 2 == 0 )
-  if ( mCellStyles.value( EvenColumns )->enabled && column % 2 == 1 )
+      color = style->cellBackgroundColor;
-    color = mCellStyles.value( EvenColumns )->cellBackgroundColor;
+  if ( QgsComposerTableStyle* style = mCellStyles.value( EvenColumns ) )
-  if ( mCellStyles.value( OddRows )->enabled && row % 2 == 0 )
+    if ( style->enabled && column % 2 == 1 )
-    color = mCellStyles.value( OddRows )->cellBackgroundColor;
+      color = style->cellBackgroundColor;
-  if ( mCellStyles.value( EvenRows )->enabled && row % 2 == 1 )
+  if ( QgsComposerTableStyle* style = mCellStyles.value( OddRows ) )
-    color = mCellStyles.value( EvenRows )->cellBackgroundColor;
+    if ( style->enabled && row % 2 == 0 )
-  if ( mCellStyles.value( FirstColumn )->enabled && column == 0 )
+      color = style->cellBackgroundColor;
-    color = mCellStyles.value( FirstColumn )->cellBackgroundColor;
+  if ( QgsComposerTableStyle* style = mCellStyles.value( EvenRows ) )
-  if ( mCellStyles.value( LastColumn )->enabled && column == mColumns.count() - 1 )
+    if ( style->enabled && row % 2 == 1 )
-    color = mCellStyles.value( LastColumn )->cellBackgroundColor;
+      color = style->cellBackgroundColor;
-  if ( mCellStyles.value( HeaderRow )->enabled && row == -1 )
+  if ( QgsComposerTableStyle* style = mCellStyles.value( FirstColumn ) )
-    color = mCellStyles.value( HeaderRow )->cellBackgroundColor;
+    if ( style->enabled && column == 0 )
-  if ( mCellStyles.value( FirstRow )->enabled && row == 0 )
+      color = style->cellBackgroundColor;
-    color = mCellStyles.value( FirstRow )->cellBackgroundColor;
+  if ( QgsComposerTableStyle* style = mCellStyles.value( LastColumn ) )
-  if ( mCellStyles.value( LastRow )->enabled && row == mTableContents.count() - 1 )
+    if ( style->enabled && column == mColumns.count() - 1 )
-    color = mCellStyles.value( LastRow )->cellBackgroundColor;
+      color = style->cellBackgroundColor;
+  if ( QgsComposerTableStyle* style = mCellStyles.value( HeaderRow ) )
+    if ( style->enabled && row == -1 )
+      color = style->cellBackgroundColor;
+  if ( QgsComposerTableStyle* style = mCellStyles.value( FirstRow ) )
+    if ( style->enabled && row == 0 )
+      color = style->cellBackgroundColor;
+  if ( QgsComposerTableStyle* style = mCellStyles.value( LastRow ) )
+    if ( style->enabled && row == mTableContents.count() - 1 )
+      color = style->cellBackgroundColor;
 
   return color;
 }

src/core/qgseditformconfig.cpp

@@ -520,10 +520,13 @@ QgsAttributeEditorElement* QgsEditFormConfig::attributeEditorElementFromDomEleme
     newElement = relElement;
   }
 
-  if ( elem.hasAttribute( QStringLiteral( "showLabel" ) ) )
+  if ( newElement )
-    newElement->setShowLabel( elem.attribute( QStringLiteral( "showLabel" ) ).toInt() );
+  {
-  else
+    if ( elem.hasAttribute( QStringLiteral( "showLabel" ) ) )
-    newElement->setShowLabel( true );
+      newElement->setShowLabel( elem.attribute( QStringLiteral( "showLabel" ) ).toInt() );
+    else
+      newElement->setShowLabel( true );
+  }
 
   return newElement;
 }

src/core/qgsvectorlayerfeatureiterator.cpp

@@ -746,10 +746,17 @@ void QgsVectorLayerFeatureIterator::addVirtualAttributes( QgsFeature& f )
 void QgsVectorLayerFeatureIterator::addExpressionAttribute( QgsFeature& f, int attrIndex )
 {
   QgsExpression* exp = mExpressionFieldInfo.value( attrIndex );
-  mExpressionContext->setFeature( f );
+  if ( exp )
-  QVariant val = exp->evaluate( mExpressionContext.data() );
+  {
-  mSource->mFields.at( attrIndex ).convertCompatible( val );
+    mExpressionContext->setFeature( f );
-  f.setAttribute( attrIndex, val );
+    QVariant val = exp->evaluate( mExpressionContext.data() );
+    mSource->mFields.at( attrIndex ).convertCompatible( val );
+    f.setAttribute( attrIndex, val );
+  }
+  else
+  {
+    f.setAttribute( attrIndex, QVariant() );
+  }
 }
 
 bool QgsVectorLayerFeatureIterator::prepareSimplification( const QgsSimplifyMethod& simplifyMethod )

src/core/raster/qgsrasterlayer.cpp

@@ -948,6 +948,10 @@ void QgsRasterLayer::setContrastEnhancement( QgsContrastEnhancement::ContrastEnh
     myRasterRenderer = myPseudoColorRenderer;
     myMinMaxOrigin = myPseudoColorRenderer->minMaxOrigin();
   }
+  else
+  {
+    return;
+  }
 
   Q_FOREACH ( int myBand, myBands )
   {

src/core/symbology-ng/qgsrendererregistry.cpp

@@ -125,7 +125,8 @@ QStringList QgsRendererRegistry::renderersList( QgsRendererAbstractMetadata::Lay
   QStringList renderers;
   Q_FOREACH ( const QString& renderer, mRenderersOrder )
   {
-    if ( mRenderers.value( renderer )->compatibleLayerTypes() & layerTypes )
+    QgsRendererAbstractMetadata* r = mRenderers.value( renderer );
+    if ( r && r->compatibleLayerTypes() & layerTypes )
       renderers << renderer;
   }
   return renderers;

src/gui/qgsvariableeditorwidget.cpp

@@ -344,12 +344,8 @@ void QgsVariableEditorTree::refreshScopeVariables( QgsExpressionContextScope* sc
 
   Q_FOREACH ( const QString& name, scope->filteredVariableNames() )
   {
-    QTreeWidgetItem* item;
+    QTreeWidgetItem* item = mVariableToItem.value( qMakePair( scopeIndex, name ) );
-    if ( mVariableToItem.contains( qMakePair( scopeIndex, name ) ) )
+    if ( !item )
-    {
-      item = mVariableToItem.value( qMakePair( scopeIndex, name ) );
-    }
-    else
     {
       item = new QTreeWidgetItem( scopeItem );
       mVariableToItem.insert( qMakePair( scopeIndex, name ), item );

src/providers/grass/qgsgrassprovidermodule.cpp

@@ -858,6 +858,10 @@ bool QgsGrassMapsetItem::handleDrop( const QMimeData * data, Qt::DropAction )
       QgsGrassObject vectorObject( mGrassObject.gisdbase(), mGrassObject.location(), mGrassObject.mapset(), destName, QgsGrassObject::Vector );
       import = new QgsGrassVectorImport( vectorProvider, vectorObject ); // takes provider ownership
     }
+    else
+    {
+      return false;
+    }
 
     connect( import, SIGNAL( finished( QgsGrassImport* ) ), SLOT( onImportFinished( QgsGrassImport* ) ) );
 

src/providers/wms/qgswmsprovider.cpp

@@ -2925,11 +2925,12 @@ QgsRasterIdentifyResult QgsWmsProvider::identify( const QgsPoint & thePoint, Qgs
           params.insert( QStringLiteral( "featureType" ), featureTypeName );
           params.insert( QStringLiteral( "getFeatureInfoUrl" ), requestUrl.toString() );
           featureStore.setParams( params );
-          Q_FOREACH ( QgsFeatureId id, features.keys() )
+          QMap<QgsFeatureId, QgsFeature* >::const_iterator featIt = features.constBegin();
+          for ( ; featIt != features.constEnd(); ++featIt )
           {
-            QgsFeature * feature = features.value( id );
+            QgsFeature * feature = featIt.value();
 
-            QgsDebugMsg( QString( "feature id = %1 : %2 attributes" ).arg( id ).arg( feature->attributes().size() ) );
+            QgsDebugMsg( QString( "feature id = %1 : %2 attributes" ).arg( featIt.key() ).arg( feature->attributes().size() ) );
 
             if ( coordinateTransform.isValid() && feature->hasGeometry() )
             {

tests/src/providers/grass/testqgsgrassprovider.cpp

@@ -1216,6 +1216,7 @@ void TestQgsGrassProvider::edit()
         grassLayer->startEditing();
         grassProvider->startEditing( grassLayer );
 
+        Q_ASSERT( expectedLayer );
         expectedLayer->startEditing();
       }
 
@@ -1582,7 +1583,9 @@ bool TestQgsGrassProvider::compare( QMap<QString, QgsVectorLayer *> layers, bool
 {
   Q_FOREACH ( const QString & grassUri, layers.keys() )
   {
-    if ( !compare( grassUri, layers.value( grassUri ), ok ) )
+    QgsVectorLayer* layer = layers.value( grassUri );
+    Q_ASSERT( layer );
+    if ( !compare( grassUri, layer, ok ) )
     {
       reportRow( "comparison failed: " + grassUri );
     }