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 );
 }