Add different casts from pointer and ref to avoid bugs

4 files changed, 28 insertions, 20 deletions

diff --git a/src/hb-open-type-private.hh b/src/hb-open-type-private.hh
index 232a61e..daf0c40 100644
--- a/src/hb-open-type-private.hh
+++ b/src/hb-open-type-private.hh
@@ -49,14 +49,22 @@ template <typename Type>
 inline char * CharP (Type* X)
 { return reinterpret_cast<char *>(X); }
 
-/* Cast to struct T& */
+/* Cast to struct T, reference to reference */
 template<typename Type, typename TObject>
-inline const Type& Cast(const TObject &X)
+inline const Type& CastR(const TObject &X)
 { return reinterpret_cast<const Type&> (X); }
 template<typename Type, typename TObject>
-inline Type& Cast(TObject &X)
+inline Type& CastR(TObject &X)
 { return reinterpret_cast<Type&> (X); }
 
+/* Cast to struct T, pointer to pointer */
+template<typename Type, typename TObject>
+inline const Type* CastP(const TObject *X)
+{ return reinterpret_cast<const Type*> (X); }
+template<typename Type, typename TObject>
+inline Type* CastP(TObject *X)
+{ return reinterpret_cast<Type*> (X); }
+
 /* StructAtOffset<T>(X,Ofs) returns the struct T& that is placed at memory
  * location of X plus Ofs bytes. */
 template<typename Type, typename TObject>
@@ -91,7 +99,7 @@ static const void *_NullPool[32 / sizeof (void *)];
 template <typename Type>
 static inline const Type& Null () {
   ASSERT_STATIC (sizeof (Type) <= sizeof (_NullPool));
-  return Cast<Type> (*_NullPool);
+  return *CastP<Type> (_NullPool);
 }
 
 /* Specializaiton for arbitrary-content arbitrary-sized Null objects. */
@@ -99,7 +107,7 @@ static inline const Type& Null () {
 static const char _Null##Type[size + 1] = data; /* +1 is for nul-termination in data */ \
 template <> \
 inline const Type& Null<Type> () { \
-  return Cast<Type> (*_Null##Type); \
+  return *CastP<Type> (_Null##Type); \
 } /* The following line really exists such that we end in a place needing semicolon */ \
 ASSERT_STATIC (sizeof (Type) + 1 <= sizeof (_Null##Type))
 
@@ -281,7 +289,7 @@ struct Sanitizer
     _hb_sanitize_init (&context, blob);
 
     /* Note: We drop const here */
-    Type *t = &Cast<Type> (* (char *) CharP(context.start));
+    Type *t = CastP<Type> ((void *) context.start);
 
     sane = t->sanitize (SANITIZE_ARG_INIT);
     if (sane) {
@@ -326,7 +334,7 @@ struct Sanitizer
   }
 
   static const Type& lock_instance (hb_blob_t *blob) {
-    return Cast<Type> (* (const char *) hb_blob_lock (blob));
+    return *CastP<Type> (hb_blob_lock (blob));
   }
 };
 
diff --git a/src/hb-ot-layout-gpos-private.hh b/src/hb-ot-layout-gpos-private.hh
index 73ac56d..777874b 100644
--- a/src/hb-ot-layout-gpos-private.hh
+++ b/src/hb-ot-layout-gpos-private.hh
@@ -1445,7 +1445,7 @@ struct PosLookupSubTable
 struct PosLookup : Lookup
 {
   inline const PosLookupSubTable& get_subtable (unsigned int i) const
-  { return this+Cast<OffsetArrayOf<PosLookupSubTable> > (subTable)[i]; }
+  { return this+CastR<OffsetArrayOf<PosLookupSubTable> > (subTable)[i]; }
 
   inline bool apply_once (hb_ot_layout_context_t *context,
 			  hb_buffer_t    *buffer,
@@ -1504,7 +1504,7 @@ struct PosLookup : Lookup
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
     if (HB_UNLIKELY (!Lookup::sanitize (SANITIZE_ARG))) return false;
-    OffsetArrayOf<PosLookupSubTable> &list = Cast<OffsetArrayOf<PosLookupSubTable> > (subTable);
+    OffsetArrayOf<PosLookupSubTable> &list = CastR<OffsetArrayOf<PosLookupSubTable> > (subTable);
     return SANITIZE_THIS (list);
   }
 };
@@ -1521,7 +1521,7 @@ struct GPOS : GSUBGPOS
   static const hb_tag_t Tag	= HB_OT_TAG_GPOS;
 
   inline const PosLookup& get_lookup (unsigned int i) const
-  { return Cast<PosLookup> (GSUBGPOS::get_lookup (i)); }
+  { return CastR<PosLookup> (GSUBGPOS::get_lookup (i)); }
 
   inline bool position_lookup (hb_ot_layout_context_t *context,
 			       hb_buffer_t  *buffer,
@@ -1532,7 +1532,7 @@ struct GPOS : GSUBGPOS
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
     if (HB_UNLIKELY (!GSUBGPOS::sanitize (SANITIZE_ARG))) return false;
-    OffsetTo<PosLookupList> &list = Cast<OffsetTo<PosLookupList> > (lookupList);
+    OffsetTo<PosLookupList> &list = CastR<OffsetTo<PosLookupList> > (lookupList);
     return SANITIZE_THIS (list);
   }
 };
diff --git a/src/hb-ot-layout-gsub-private.hh b/src/hb-ot-layout-gsub-private.hh
index fc3bb29..77c27a8 100644
--- a/src/hb-ot-layout-gsub-private.hh
+++ b/src/hb-ot-layout-gsub-private.hh
@@ -743,7 +743,7 @@ struct SubstLookupSubTable
 struct SubstLookup : Lookup
 {
   inline const SubstLookupSubTable& get_subtable (unsigned int i) const
-  { return this+Cast<OffsetArrayOf<SubstLookupSubTable> > (subTable)[i]; }
+  { return this+CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable)[i]; }
 
   inline static bool lookup_type_is_reverse (unsigned int lookup_type)
   { return lookup_type == SubstLookupSubTable::ReverseChainSingle; }
@@ -752,7 +752,7 @@ struct SubstLookup : Lookup
   {
     unsigned int type = get_type ();
     if (HB_UNLIKELY (type == SubstLookupSubTable::Extension))
-      return Cast<ExtensionSubst> (get_subtable(0)).is_reverse ();
+      return CastR<ExtensionSubst> (get_subtable(0)).is_reverse ();
     return lookup_type_is_reverse (type);
   }
 
@@ -839,7 +839,7 @@ struct SubstLookup : Lookup
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
     if (HB_UNLIKELY (!Lookup::sanitize (SANITIZE_ARG))) return false;
-    OffsetArrayOf<SubstLookupSubTable> &list = Cast<OffsetArrayOf<SubstLookupSubTable> > (subTable);
+    OffsetArrayOf<SubstLookupSubTable> &list = CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable);
     return SANITIZE_THIS (list);
   }
 };
@@ -856,7 +856,7 @@ struct GSUB : GSUBGPOS
   static const hb_tag_t Tag	= HB_OT_TAG_GSUB;
 
   inline const SubstLookup& get_lookup (unsigned int i) const
-  { return Cast<SubstLookup> (GSUBGPOS::get_lookup (i)); }
+  { return CastR<SubstLookup> (GSUBGPOS::get_lookup (i)); }
 
   inline bool substitute_lookup (hb_ot_layout_context_t *context,
 				 hb_buffer_t  *buffer,
@@ -868,7 +868,7 @@ struct GSUB : GSUBGPOS
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
     if (HB_UNLIKELY (!GSUBGPOS::sanitize (SANITIZE_ARG))) return false;
-    OffsetTo<SubstLookupList> &list = Cast<OffsetTo<SubstLookupList> > (lookupList);
+    OffsetTo<SubstLookupList> &list = CastR<OffsetTo<SubstLookupList> > (lookupList);
     return SANITIZE_THIS (list);
   }
 };
@@ -896,7 +896,7 @@ inline bool ExtensionSubst::is_reverse (void) const
 {
   unsigned int type = get_type ();
   if (HB_UNLIKELY (type == SubstLookupSubTable::Extension))
-    return Cast<ExtensionSubst> (get_subtable()).is_reverse ();
+    return CastR<ExtensionSubst> (get_subtable()).is_reverse ();
   return SubstLookup::lookup_type_is_reverse (type);
 }
 
diff --git a/src/main.cc b/src/main.cc
index badf91b..2e0927a 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -61,7 +61,7 @@ main (int argc, char **argv)
 
   printf ("Opened font file %s: %d bytes long\n", argv[1], len);
 
-  const OpenTypeFontFile &ot = Cast<OpenTypeFontFile> (font_data);
+  const OpenTypeFontFile &ot = *CastP<OpenTypeFontFile> (font_data);
 
   switch (ot.get_tag ()) {
   case OpenTypeFontFile::TrueTypeTag:
@@ -99,7 +99,7 @@ main (int argc, char **argv)
       case GSUBGPOS::GPOSTag:
 	{
 
-	const GSUBGPOS &g = Cast<GSUBGPOS> (font_data + table.offset);
+	const GSUBGPOS &g = *CastP<GSUBGPOS> (font_data + table.offset);
 
 	int num_scripts = g.get_script_count ();
 	printf ("    %d script(s) found in table\n", num_scripts);
@@ -162,7 +162,7 @@ main (int argc, char **argv)
       case GDEF::Tag:
 	{
 
-	const GDEF &gdef = Cast<GDEF> (font_data + table.offset);
+	const GDEF &gdef = *CastP<GDEF> (font_data + table.offset);
 
 	printf ("    Has %sglyph classes\n",
 		  gdef.has_glyph_classes () ? "" : "no ");