assimp/issues/685: add test for correct usage.

include/assimp/matrix4x4.inl

@@ -238,16 +238,22 @@ inline aiMatrix4x4t<TReal>& aiMatrix4x4t<TReal>::Inverse()
 
 // ----------------------------------------------------------------------------------------
 template <typename TReal>
-inline TReal* aiMatrix4x4t<TReal>::operator[](unsigned int p_iIndex)
-{
+inline TReal* aiMatrix4x4t<TReal>::operator[](unsigned int p_iIndex) {
+    if (p_iIndex > 3) {
+        return NULL;
+    }
+
     // XXX this is UB. Has been for years. The fact that it works now does not make it better.
     return &this->a1 + p_iIndex * 4;
 }
 
 // ----------------------------------------------------------------------------------------
 template <typename TReal>
-inline const TReal* aiMatrix4x4t<TReal>::operator[](unsigned int p_iIndex) const
-{
+inline const TReal* aiMatrix4x4t<TReal>::operator[](unsigned int p_iIndex) const {
+    if (p_iIndex > 3) {
+        return NULL;
+    }
+
     // XXX same
     return &this->a1 + p_iIndex * 4;
 }

test/CMakeLists.txt

@@ -28,6 +28,7 @@ SET( TEST_SRCS
   unit/utJoinVertices.cpp
   unit/utLimitBoneWeights.cpp
   unit/utMaterialSystem.cpp
+  unit/utMatrix4x4.cpp
   unit/utPretransformVertices.cpp
   unit/utRemoveComments.cpp
   unit/utRemoveComponent.cpp

test/unit/utMatrix4x4.cpp

@@ -0,0 +1,87 @@
+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (assimp)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2014, assimp team
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the following
+conditions are met:
+
+* Redistributions of source code must retain the above
+copyright notice, this list of conditions and the
+following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other
+materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+contributors may be used to endorse or promote products
+derived from this software without specific prior
+written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+---------------------------------------------------------------------------
+*/
+
+#include "UnitTestPCH.h"
+
+using namespace Assimp;
+
+class utMatrix4x4Test : public ::testing::Test {
+
+};
+
+TEST_F( utMatrix4x4Test, IndexOperatorTest ) {
+    aiMatrix4x4 m;
+    float *a0 = m[ 0 ];
+    EXPECT_FLOAT_EQ( 1.0f, *a0 );
+    float *a1 = a0+1;
+    EXPECT_FLOAT_EQ( 0.0f, *a1 );
+    float *a2 = a0 + 2;
+    EXPECT_FLOAT_EQ( 0.0f, *a2 );
+    float *a3 = a0 + 3;
+    EXPECT_FLOAT_EQ( 0.0f, *a3 );
+
+    float *a4 = m[ 1 ];
+    EXPECT_FLOAT_EQ( 0.0f, *a4 );
+    float *a5 = a4 + 1;
+    EXPECT_FLOAT_EQ( 1.0f, *a5 );
+    float *a6 = a4 + 2;
+    EXPECT_FLOAT_EQ( 0.0f, *a6 );
+    float *a7 = a4 + 3;
+    EXPECT_FLOAT_EQ( 0.0f, *a7 );
+
+    float *a8 = m[ 2 ];
+    EXPECT_FLOAT_EQ( 0.0f, *a8 );
+    float *a9 = a8 + 1;
+    EXPECT_FLOAT_EQ( 0.0f, *a9 );
+    float *a10 = a8 + 2;
+    EXPECT_FLOAT_EQ( 1.0f, *a10 );
+    float *a11 = a8 + 3;
+    EXPECT_FLOAT_EQ( 0.0f, *a11 );
+
+    float *a12 = m[ 3 ];
+    EXPECT_FLOAT_EQ( 0.0f, *a12 );
+    float *a13 = a12 + 1;
+    EXPECT_FLOAT_EQ( 0.0f, *a13 );
+    float *a14 = a12 + 2;
+    EXPECT_FLOAT_EQ( 0.0f, *a14 );
+    float *a15 = a12 + 3;
+    EXPECT_FLOAT_EQ( 1.0f, *a15 );
+}