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
@@ -159,110 +159,112 @@ void OpieScreenSaver::setMode ( int mode )
         if ( mode > m_disable_suspend )
                 setInterval ( -1 );
         m_disable_suspend = mode;
 }
 
 
 void OpieScreenSaver::setBacklight ( int bright )
 {
         // Read from config
         Config config ( "apm" );
         config. setGroup ( m_on_ac ? "AC" : "Battery" );
         m_backlight_normal = config. readNumEntry ( "Brightness", m_on_ac ? 255 : 127 );
 
         m_use_light_sensor = config. readBoolEntry ( "LightSensor", false );
 
         //qDebug ( "setBacklight: %d (ls: %d)", m_backlight_normal, m_use_light_sensor ? 1 : 0 );
 
         killTimers ( );
         if ( m_use_light_sensor ) {
                 QStringList sl = config. readListEntry ( "LightSensorData", ';' );
                 
                 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 ) {
                 // Forced on
                 m_backlight_forcedoff = false;
                 bright = -1;
         }
         if ( m_backlight_forcedoff && bright != -2 )
                 return ;
         if ( bright == -2 ) {
                 // Toggle between off and on
                 bright = m_backlight_current ? 0 : -1;
                 m_backlight_forcedoff = !bright;
         }
         if ( bright == -1 )
                 bright = m_use_light_sensor ? m_backlight_sensor : m_backlight_normal;
 
         if ( bright != m_backlight_current ) {
                 ODevice::inst ( )-> setDisplayBrightness ( bright );
                 m_backlight_current = 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 );
 }
 
 
 void OpieScreenSaver::setDisplayState ( bool on )
 {
         if ( m_lcd_status != on ) {
                 ODevice::inst ( ) -> setDisplayStatus ( on );
                 m_lcd_status = on;
         }
 }
 
 
 void OpieScreenSaver::powerStatusChanged ( PowerStatus ps )
 {
         bool newonac = ( ps. acStatus ( ) == PowerStatus::Online );
         
         if ( newonac != m_on_ac ) {
                 m_on_ac = newonac;
                 setInterval ( -1 );
                 setBacklight ( -1 );
                         restore ( );    
         }