From 45ca0a5ab8998f3ace9008f058f57191e8dfc317 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Wed, 15 Jan 2020 18:33:19 +0000
Subject: [PATCH] Avoid divide-by-zero.

---
 bitmap2component/bitmap2cmp_gui.cpp         | 6 ++++++
 gerbview/am_primitive.cpp                   | 7 ++++++-
 libs/kimath/src/geometry/geometry_utils.cpp | 6 ++++--
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/bitmap2component/bitmap2cmp_gui.cpp b/bitmap2component/bitmap2cmp_gui.cpp
index 3c173371bb..75f87ac047 100644
--- a/bitmap2component/bitmap2cmp_gui.cpp
+++ b/bitmap2component/bitmap2cmp_gui.cpp
@@ -63,6 +63,9 @@ IMAGE_SIZE::IMAGE_SIZE()
 
 void IMAGE_SIZE::SetOutputSizeFromInitialImageSize()
 {
+    // Safety-check to guarantee no divide-by-zero
+    m_originalDPI = std::max( 1, m_originalDPI );
+
     // Set the m_outputSize value from the m_originalSizePixels and the selected unit
     if( m_unit == EDA_UNITS::MILLIMETRES )
     {
@@ -97,6 +100,9 @@ int IMAGE_SIZE::GetOutputDPI()
         outputDPI = KiROUND( m_outputSize );
     }
 
+    // Zero is not a DPI, and may cause divide-by-zero errors...
+    outputDPI = std::max( 1, outputDPI );
+
     return outputDPI;
 }
 
diff --git a/gerbview/am_primitive.cpp b/gerbview/am_primitive.cpp
index 2518c0bb95..6d4c4588f2 100644
--- a/gerbview/am_primitive.cpp
+++ b/gerbview/am_primitive.cpp
@@ -556,7 +556,12 @@ void AM_PRIMITIVE::ConvertShapeToPolygon( const GERBER_DRAW_ITEM* aParent,
         // params = center.x (unused here), center.y (unused here), outside diam, inside diam, crosshair thickness
         int outerRadius   = scaletoIU( params[2].GetValue( tool ), m_GerbMetric ) / 2;
         int innerRadius   = scaletoIU( params[3].GetValue( tool ), m_GerbMetric ) / 2;
-        int halfthickness = scaletoIU( params[4].GetValue( tool ), m_GerbMetric ) / 2;
+
+        // Safety checks to guarantee no divide-by-zero
+        outerRadius = std::max( 1, outerRadius );
+        innerRadius = std::max( 1, innerRadius );
+
+        int halfthickness  = scaletoIU( params[4].GetValue( tool ), m_GerbMetric ) / 2;
         double angle_start = RAD2DECIDEG( asin( (double) halfthickness / innerRadius ) );
 
         // Draw shape in the first cadrant (X and Y > 0)
diff --git a/libs/kimath/src/geometry/geometry_utils.cpp b/libs/kimath/src/geometry/geometry_utils.cpp
index 74625f28cc..e4898a637f 100644
--- a/libs/kimath/src/geometry/geometry_utils.cpp
+++ b/libs/kimath/src/geometry/geometry_utils.cpp
@@ -42,6 +42,9 @@ int GetArcToSegmentCount( int aRadius, int aErrorMax, double aArcAngleDegree )
     // calculate the number of segments to approximate a circle by segments
     // given the max distance between the middle of a segment and the circle
 
+    // avoid divide-by-zero
+    aRadius = std::max( 1, aRadius );
+
     // error relative to the radius value:
     double rel_error = (double)aErrorMax / aRadius;
     // minimal arc increment in degrees:
@@ -67,8 +70,7 @@ double GetCircletoPolyCorrectionFactor( int aSegCountforCircle )
      * therefore, to move the middle of the segment to the circle (distance = radius)
      * the correctionFactor is 1 /cos( PI/aSegCountforCircle  )
      */
-    if( aSegCountforCircle < MIN_SEGCOUNT_FOR_CIRCLE )
-        aSegCountforCircle = MIN_SEGCOUNT_FOR_CIRCLE;
+    aSegCountforCircle = std::max( MIN_SEGCOUNT_FOR_CIRCLE, aSegCountforCircle );
 
     return 1.0 / cos( M_PI / aSegCountforCircle );
 }