libicon: Fix dangling references to VertexSource in PathTransformer

PathTransformer keeps a reference to the VertexSource used (which can be
either another PathTransformer, or the base path for a shape). When a
shape is cloned, this should be retargetted to the new object in the
clone.

However, references are not settable, and so, what would happen instead
is the original (non-cloned) vertex source was reinitialized (through
the default implementation of the assignment operator) using data from
the clone, and the clone would still point to it. Then, if the original
object is deleted, the clone would point to freed memory.

To avoid this problem, replace the reference with a pointer (which can
be set to point elsewhere, as the code intended to do). To make sure
this does not happen again, make the VertexSource copy constructor and
assignment operator private, and deleted when the compiler supports
that.

Fixes #18577

Change-Id: I8870d9471c5064e922a84eff8447cbda783b13e6
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7052
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Zardshard <0azrune6@zard.anonaddy.com>

src/libs/icon/generic/VertexSource.h

@@ -27,6 +27,17 @@ class VertexSource {
 	/*! Determines whether open paths should be closed or left open. */
 	virtual	bool				WantsOpenPaths() const = 0;
 	virtual	double				ApproximationScale() const = 0;
+
+ private:
+	// Not allowed
+#if __GNUC__ <= 2
+#define NOT_ALLOWED
+#else
+#define NOT_ALLOWED = delete
+#endif
+	VertexSource(const VertexSource& other) NOT_ALLOWED;
+	VertexSource& operator=(const VertexSource& other) NOT_ALLOWED;
+#undef NOT_ALLOWED
 };
 
 

src/libs/icon/transformer/AffineTransformer.cpp

@@ -61,7 +61,7 @@ AffineTransformer::~AffineTransformer()
 Transformer*
 AffineTransformer::Clone() const
 {
-	AffineTransformer* clone = new (nothrow) AffineTransformer(fSource);
+	AffineTransformer* clone = new (nothrow) AffineTransformer(*fSource);
 	if (clone)
 		clone->multiply(*this);
 	return clone;
@@ -93,7 +93,7 @@ AffineTransformer::SetSource(VertexSource& source)
 double
 AffineTransformer::ApproximationScale() const
 {
-	return fabs(fSource.ApproximationScale() * scale());
+	return fabs(fSource->ApproximationScale() * scale());
 }
 
 // #pragma mark -

src/libs/icon/transformer/ContourTransformer.cpp

@@ -73,7 +73,7 @@ ContourTransformer::~ContourTransformer()
 Transformer*
 ContourTransformer::Clone() const
 {
-	ContourTransformer* clone = new (nothrow) ContourTransformer(fSource);
+	ContourTransformer* clone = new (nothrow) ContourTransformer(*fSource);
 	if (clone) {
 		clone->line_join(line_join());
 		clone->inner_join(inner_join());
@@ -111,7 +111,7 @@ ContourTransformer::SetSource(VertexSource& source)
 double
 ContourTransformer::ApproximationScale() const
 {
-	double scale = fSource.ApproximationScale();
+	double scale = fSource->ApproximationScale();
 	double factor = fabs(width());
 	if (factor > 1.0)
 		scale *= factor;

src/libs/icon/transformer/PathTransformer.h

@@ -24,25 +24,25 @@ class PathTransformer : public VertexSource
 {
 public:
 								PathTransformer(VertexSource& source)
-									: fSource(source) {}
+									: fSource(&source) {}
 	virtual						~PathTransformer() {}
 
 	// PathTransformer
 	virtual	void				rewind(unsigned path_id)
-									{ fSource.rewind(path_id); }
+									{ fSource->rewind(path_id); }
     virtual	unsigned			vertex(double* x, double* y)
-									{ return fSource.vertex(x, y); }
+									{ return fSource->vertex(x, y); }
 
 	virtual	void				SetSource(VertexSource& source)
-									{ fSource = source; }
+									{ fSource = &source; }
 
 	virtual	bool				WantsOpenPaths() const
-									{ return fSource.WantsOpenPaths(); }
+									{ return fSource->WantsOpenPaths(); }
 	virtual	double				ApproximationScale() const
-									{ return fSource.ApproximationScale(); }
+									{ return fSource->ApproximationScale(); }
 
 protected:
-			VertexSource&		fSource;
+			VertexSource*		fSource;
 };
 
 

src/libs/icon/transformer/PerspectiveTransformer.cpp

@@ -76,8 +76,8 @@ PerspectiveTransformer::PerspectiveTransformer(const PerspectiveTransformer& oth
 #else
 	: Transformer(""),
 #endif
-	  PathTransformer(other.fSource),
-	  Perspective(fSource, *this),
+	  PathTransformer(*other.fSource),
+	  Perspective(*fSource, *this),
 	  fShape(other.fShape)
 #ifdef ICON_O_MATIC
 	, fInverted(other.fInverted),
@@ -162,7 +162,7 @@ PerspectiveTransformer::SetSource(VertexSource& source)
 double
 PerspectiveTransformer::ApproximationScale() const
 {
-	return fSource.ApproximationScale() * scale();
+	return fSource->ApproximationScale() * scale();
 }
 
 
@@ -223,7 +223,7 @@ PerspectiveTransformer::ObjectChanged(const Observable* object)
 	uint32 pathID[1];
 	pathID[0] = 0;
 	double left, top, right, bottom;
-	agg::bounding_rect(fSource, pathID, 0, 1, &left, &top, &right, &bottom);
+	agg::bounding_rect(*fSource, pathID, 0, 1, &left, &top, &right, &bottom);
 	BRect newFromBox = BRect(left, top, right, bottom);
 
 	// Stop if nothing we care about has changed

src/libs/icon/transformer/StrokeTransformer.cpp

@@ -76,7 +76,7 @@ StrokeTransformer::~StrokeTransformer()
 Transformer*
 StrokeTransformer::Clone() const
 {
-	StrokeTransformer* clone = new (nothrow) StrokeTransformer(fSource);
+	StrokeTransformer* clone = new (nothrow) StrokeTransformer(*fSource);
 	if (clone) {
 		clone->line_cap(line_cap());
 		clone->line_join(line_join());
@@ -122,7 +122,7 @@ StrokeTransformer::WantsOpenPaths() const
 double
 StrokeTransformer::ApproximationScale() const
 {
-	double scale = fSource.ApproximationScale();
+	double scale = fSource->ApproximationScale();
 	double factor = fabs(width());
 	if (factor > 1.0)
 		scale *= factor;