Fix crash with invalid selections and memory corruptionwhen updating image in terminal display.

svn path=/trunk/KDE/kdebase/apps/konsole/; revision=670435

src/Screen.cpp

@@ -1379,14 +1379,25 @@ static QString makeString(int *m, int d, bool stripTrailingSpaces)
 }*/
 
 
+bool Screen::isSelectionValid() const
+{
+    return ( sel_TL >= 0 && sel_BR >= 0 );
+}
+
 void Screen::writeSelectionToStream(TerminalCharacterDecoder* decoder)
 {
+    // do nothing if selection is invalid
+    if ( !isSelectionValid() )
+        return;
+
 	int top = sel_TL / columns;	
 	int left = sel_TL % columns;
 
 	int bottom = sel_BR / columns;
 	int right = sel_BR % columns;
 
+    Q_ASSERT( top >= 0 && left >= 0 && bottom >= 0 && right >= 0 );
+
     //qDebug() << "sel_TL = " << sel_TL;
     //qDebug() << "columns = " << columns;
 

src/Screen.h

@@ -379,6 +379,8 @@ private: // helper
     void effectiveRendition();
     void reverseRendition(Character* p);
 
+    bool isSelectionValid() const;
+
     /*
        The state of the screen is more complex as one would
        expect first. The screem does really do part of the

src/TECommon.h

@@ -222,6 +222,8 @@ public:
             _v = co >> 8;
             _w = co;
             break;
+        default:
+            Q_ASSERT(false);
     }
   }
     

src/TerminalDisplay.cpp

@@ -847,7 +847,7 @@ void TerminalDisplay::updateImage()
   for (y = 0; y < linesToUpdate; y++)
   {
     const Character*       currentLine = &_image[y*this->_columns];
-    const Character* const newLine = &newimg[y*_columns];
+    const Character* const newLine = &newimg[y*columns];
 
     bool updateLine = false;