fix null being passed to memcpy

src/bitset.c

@@ -49,7 +49,8 @@ void b2GrowBitSet( b2BitSet* bitSet, uint32_t blockCount )
 		bitSet->blockCapacity = blockCount + blockCount / 2;
 		uint64_t* newBits = b2Alloc( bitSet->blockCapacity * sizeof( uint64_t ) );
 		memset( newBits, 0, bitSet->blockCapacity * sizeof( uint64_t ) );
-		memcpy( newBits, bitSet->bits, bitSet->blockCount * sizeof( uint64_t ) );
+		B2_ASSERT( bitSet->bits != NULL );
+		memcpy( newBits, bitSet->bits, oldCapacity * sizeof( uint64_t ) );
 		b2Free( bitSet->bits, oldCapacity * sizeof( uint64_t ) );
 		bitSet->bits = newBits;
 	}

src/bitset.h

@@ -8,7 +8,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-// Bit set provides fast operations on large arrays of bits
+// Bit set provides fast operations on large arrays of bits.
 typedef struct b2BitSet
 {
 	uint64_t* bits;

src/block_array.c

@@ -102,6 +102,7 @@ b2BodySim* b2AddBodySim( b2BodySimArray* array )
 	{
 		int newCapacity = 2 * array->capacity;
 		b2BodySim* newElements = b2Alloc( newCapacity * elementSize );
+		B2_ASSERT( array->data != NULL );
 		memcpy( newElements, array->data, array->capacity * elementSize );
 		b2Free( array->data, array->capacity * elementSize );
 		array->data = newElements;
@@ -126,6 +127,7 @@ b2BodyState* b2AddBodyState( b2BodyStateArray* array )
 	{
 		int newCapacity = 2 * array->capacity;
 		b2BodyState* newElements = b2Alloc( newCapacity * elementSize );
+		B2_ASSERT( array->data != NULL );
 		memcpy( newElements, array->data, array->capacity * elementSize );
 		b2Free( array->data, array->capacity * elementSize );
 		array->data = newElements;
@@ -150,6 +152,7 @@ b2ContactSim* b2AddContact( b2ContactArray* array )
 	{
 		int newCapacity = 2 * array->capacity;
 		b2ContactSim* newElements = b2Alloc( newCapacity * elementSize );
+		B2_ASSERT( array->data != NULL );
 		memcpy( newElements, array->data, array->capacity * elementSize );
 		b2Free( array->data, array->capacity * elementSize );
 		array->data = newElements;
@@ -174,6 +177,7 @@ b2JointSim* b2AddJoint( b2JointArray* array )
 	{
 		int newCapacity = 2 * array->capacity;
 		b2JointSim* newElements = b2Alloc( newCapacity * elementSize );
+		B2_ASSERT( array->data != NULL );
 		memcpy( newElements, array->data, array->capacity * elementSize );
 		b2Free( array->data, array->capacity * elementSize );
 		array->data = newElements;
@@ -198,6 +202,7 @@ b2IslandSim* b2AddIsland( b2IslandArray* array )
 	{
 		int newCapacity = 2 * array->capacity;
 		b2IslandSim* newElements = b2Alloc( newCapacity * elementSize );
+		B2_ASSERT( array->data != NULL );
 		memcpy( newElements, array->data, array->capacity * elementSize );
 		b2Free( array->data, array->capacity * elementSize );
 		array->data = newElements;

src/constraint_graph.c

@@ -30,19 +30,19 @@ _Static_assert( b2_graphColorCount == 12, "graph color count assumed to be 12" )
 void b2CreateGraph( b2ConstraintGraph* graph, int bodyCapacity )
 {
 	_Static_assert( b2_graphColorCount >= 2, "must have at least two constraint graph colors" );
+	_Static_assert( b2_overflowIndex == b2_graphColorCount - 1, "bad over flow index");
 
 	*graph = ( b2ConstraintGraph ){ 0 };
 
 	bodyCapacity = b2MaxInt( bodyCapacity, 8 );
-	for ( int i = 0; i < b2_graphColorCount; ++i )
+
+	// Initialize graph color bit set.
+	// No bitset for overflow color.
+	for ( int i = 0; i < b2_overflowIndex; ++i )
 	{
 		b2GraphColor* color = graph->colors + i;
-
-		if ( i != b2_overflowIndex )
-		{
-			color->bodySet = b2CreateBitSet( bodyCapacity );
-			b2SetBitCountAndClear( &color->bodySet, bodyCapacity );
-		}
+		color->bodySet = b2CreateBitSet( bodyCapacity );
+		b2SetBitCountAndClear( &color->bodySet, bodyCapacity );
 	}
 }
 
@@ -51,6 +51,10 @@ void b2DestroyGraph( b2ConstraintGraph* graph )
 	for ( int i = 0; i < b2_graphColorCount; ++i )
 	{
 		b2GraphColor* color = graph->colors + i;
+
+		// The bit set should never be used on the overflow color
+		B2_ASSERT( i != b2_overflowIndex || color->bodySet.bits == NULL );
+
 		b2DestroyBitSet( &color->bodySet );
 
 		b2DestroyContactArray( &color->contacts );
@@ -220,7 +224,7 @@ static int b2AssignJointColor( b2ConstraintGraph* graph, int bodyIdA, int bodyId
 #if B2_FORCE_OVERFLOW == 0
 	if ( staticA == false && staticB == false )
 	{
-		for ( int i = 0; i < b2_graphColorCount; ++i )
+		for ( int i = 0; i < b2_overflowIndex; ++i )
 		{
 			b2GraphColor* color = graph->colors + i;
 			if ( b2GetBit( &color->bodySet, bodyIdA ) || b2GetBit( &color->bodySet, bodyIdB ) )
@@ -235,7 +239,7 @@ static int b2AssignJointColor( b2ConstraintGraph* graph, int bodyIdA, int bodyId
 	}
 	else if ( staticA == false )
 	{
-		for ( int i = 0; i < b2_graphColorCount; ++i )
+		for ( int i = 0; i < b2_overflowIndex; ++i )
 		{
 			b2GraphColor* color = graph->colors + i;
 			if ( b2GetBit( &color->bodySet, bodyIdA ) )
@@ -249,7 +253,7 @@ static int b2AssignJointColor( b2ConstraintGraph* graph, int bodyIdA, int bodyId
 	}
 	else if ( staticB == false )
 	{
-		for ( int i = 0; i < b2_graphColorCount; ++i )
+		for ( int i = 0; i < b2_overflowIndex; ++i )
 		{
 			b2GraphColor* color = graph->colors + i;
 			if ( b2GetBit( &color->bodySet, bodyIdB ) )

src/constraint_graph.h

@@ -22,8 +22,9 @@ typedef struct b2World b2World;
 
 typedef struct b2GraphColor
 {
-	// base on bodyId so this is over-sized to encompass static bodies
+	// This bitset is indexed by bodyId so this is over-sized to encompass static bodies
 	// however I never traverse these bits or use the bit count for anything
+	// This bitset is unused on the overflow color.
 	b2BitSet bodySet;
 
 	// cache friendly arrays

src/dynamic_tree.c

@@ -87,6 +87,7 @@ static int32_t b2AllocateNode( b2DynamicTree* tree )
 		int32_t oldCapcity = tree->nodeCapacity;
 		tree->nodeCapacity += oldCapcity >> 1;
 		tree->nodes = (b2TreeNode*)b2Alloc( tree->nodeCapacity * sizeof( b2TreeNode ) );
+		B2_ASSERT( oldNodes != NULL );
 		memcpy( tree->nodes, oldNodes, tree->nodeCount * sizeof( b2TreeNode ) );
 		b2Free( oldNodes, oldCapcity * sizeof( b2TreeNode ) );