From 81cb6d0c3fb92dd15f0a0e0d2d32337be1617399 Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <seth@kipro-pcb.com>
Date: Wed, 13 Mar 2024 10:33:43 -0700
Subject: [PATCH] Fix race condition in zone fill

When checking collisions, the SHAPE_POLY_SET::Collide() routine is not
const because it will regenerate the triangulation cache if it is out of
date (using a const_cast, grrr).  This sidesteps the issue by assigning
a mutex to the triangulation caching

Fixes https://gitlab.com/kicad/code/kicad/-/issues/17180
---
 libs/kimath/include/geometry/shape_poly_set.h | 4 +++-
 libs/kimath/src/geometry/shape_poly_set.cpp   | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/libs/kimath/include/geometry/shape_poly_set.h b/libs/kimath/include/geometry/shape_poly_set.h
index 9ba7b5407b0..ac5b2325744 100644
--- a/libs/kimath/include/geometry/shape_poly_set.h
+++ b/libs/kimath/include/geometry/shape_poly_set.h
@@ -32,6 +32,7 @@
 #include <deque>                        // for deque
 #include <iosfwd>                       // for string, stringstream
 #include <memory>
+#include <mutex>
 #include <set>                          // for set
 #include <stdexcept>                    // for out_of_range
 #include <stdlib.h>                     // for abs
@@ -1537,7 +1538,8 @@ protected:
     std::vector<POLYGON>                               m_polys;
     std::vector<std::unique_ptr<TRIANGULATED_POLYGON>> m_triangulatedPolys;
 
-    bool     m_triangulationValid = false;
+    bool        m_triangulationValid = false;
+    std::mutex  m_triangulationMutex;
 
 private:
     MD5_HASH m_hash;
diff --git a/libs/kimath/src/geometry/shape_poly_set.cpp b/libs/kimath/src/geometry/shape_poly_set.cpp
index 407c43b9c6e..dacc1e8a07c 100644
--- a/libs/kimath/src/geometry/shape_poly_set.cpp
+++ b/libs/kimath/src/geometry/shape_poly_set.cpp
@@ -2984,6 +2984,7 @@ static SHAPE_POLY_SET partitionPolyIntoRegularCellGrid( const SHAPE_POLY_SET& aP
 void SHAPE_POLY_SET::cacheTriangulation( bool aPartition, bool aSimplify,
                                          std::vector<std::unique_ptr<TRIANGULATED_POLYGON>>* aHintData )
 {
+    std::unique_lock<std::mutex> lock( m_triangulationMutex );
     bool recalculate = !m_hash.IsValid();
     MD5_HASH hash;
 
-- 
GitLab