added a sanity check to avoid a division by 0 in case the config file

contains bad data

1 files changed, 3 insertions, 1 deletions

diff --git a/core/launcher/screensaver.cpp b/core/launcher/screensaver.cpp
index 45da9ed..088ed19 100644
--- a/core/launcher/screensaver.cpp
+++ b/core/launcher/screensaver.cpp
@@ -179,24 +179,26 @@ void OpieScreenSaver::setBacklight ( int bright )
                 
                 m_sensordata [LS_SensorMin] = 40;
                 m_sensordata [LS_SensorMax] = 215;
                 m_sensordata [LS_LightMin] = 1;
                 m_sensordata [LS_LightMax] = 255;
                 m_sensordata [LS_Steps] = 12;
                         m_sensordata [LS_Interval] = 2000;      
                 
                 for ( uint i = 0; i < LS_Count; i++ ) {
                         if ( i < sl. count ( ))
                                 m_sensordata [i] = sl [i]. toInt ( );
                 }
+                if ( m_sensordata [LS_Steps] < 2 ) // sanity check to avoid SIGFPE
+                        m_sensordata [LS_Steps] = 2;
 
                 timerEvent ( 0 );
                 startTimer ( m_sensordata [LS_Interval] );
         }
 
         setBacklightInternal ( bright );
 }
 
 
 void OpieScreenSaver::setBacklightInternal ( int bright )
 {
         if ( bright == -3 ) {
@@ -224,25 +226,25 @@ void OpieScreenSaver::setBacklightInternal ( int bright )
 void OpieScreenSaver::timerEvent ( QTimerEvent * )
 {
         int s = ODevice::inst ( )-> readLightSensor ( );
         
         if ( s < m_sensordata [LS_SensorMin] )
                 m_backlight_sensor = m_sensordata [LS_LightMax];
         else if ( s >= m_sensordata [LS_SensorMax] )
                 m_backlight_sensor = m_sensordata [LS_LightMin];
         else {
                 int dx = m_sensordata [LS_SensorMax] - m_sensordata [LS_SensorMin];
                 int dy = m_sensordata [LS_LightMax] - m_sensordata [LS_LightMin];
                 
-                int stepno = ( s - m_sensordata [LS_SensorMin] ) * m_sensordata [LS_Steps] / dx;
+                int stepno = ( s - m_sensordata [LS_SensorMin] ) * m_sensordata [LS_Steps] / dx; // dx is never 0
                 
                 m_backlight_sensor = m_sensordata [LS_LightMax] - dy * stepno / ( m_sensordata [LS_Steps] - 1 );
         }
         if ( !m_backlight_sensor )
                 m_backlight_sensor = 1;
 
         // qDebug ( "f(%d) = %d [%d - %d] -> [%d - %d] / %d", s, m_backlight_sensor, m_sensordata [LS_SensorMin], m_sensordata [LS_SensorMax], m_sensordata [LS_LightMin], m_sensordata [LS_LightMax], m_sensordata [LS_Steps] );
 
         if ( m_level <= 0 )
                 setBacklightInternal ( -1 );
 }