[glyf] Use range_checker_t in composite_iter_t

src/hb-ot-glyf-table.hh

diff --git a/src/hb-ot-glyf-table.hh b/src/hb-ot-glyf-table.hh
index fd54bd3..f5a64b0 100644
--- a/src/hb-ot-glyf-table.hh
+++ b/src/hb-ot-glyf-table.hh
@@ -359,9 +359,10 @@
   struct composite_iter_t : hb_iter_with_fallback_t<composite_iter_t, const CompositeGlyphChain &>
   {
     typedef const CompositeGlyphChain *__item_t__;
-    composite_iter_t (hb_bytes_t glyph_, __item_t__ current_) : glyph (glyph_), current (current_)
+    composite_iter_t (hb_bytes_t glyph_, __item_t__ current_) :
+      glyph (glyph_), current (current_), checker (range_checker_t (glyph.arrayZ, glyph.length))
     { if (!in_range (current)) current = nullptr; }
-    composite_iter_t () : glyph (hb_bytes_t ()), current (nullptr) {}
+    composite_iter_t () : glyph (hb_bytes_t ()), current (nullptr), checker (range_checker_t (nullptr, 0)) {}
 
     const CompositeGlyphChain &__item__ () const { return *current; }
     bool __more__ () const { return current; }
@@ -379,13 +380,14 @@
 
     bool in_range (const CompositeGlyphChain *composite) const
     {
-      return glyph.sub_array ((const char *) composite - (const char *) &glyph,
-			       CompositeGlyphChain::min_size).as<CompositeGlyphChain> () != &Null (CompositeGlyphChain);
+      return checker.in_range (composite, CompositeGlyphChain::min_size)
+	  && checker.in_range (composite, composite->get_size ());
     }
 
     private:
     hb_bytes_t glyph;
     __item_t__ current;
+    range_checker_t checker;
   };
 
   struct Glyph
@@ -569,7 +571,7 @@
 			       const bool phantom_only=false) const
       {
 	const HBUINT16 *endPtsOfContours = &StructAfter<HBUINT16> (header);
-	range_checker_t checker (bytes.arrayZ, 0, bytes.length);
+	range_checker_t checker (bytes.arrayZ, bytes.length);
 	int num_contours = header.numberOfContours;
 	if (unlikely (!checker.in_range (&endPtsOfContours[num_contours + 1]))) return false;
 	unsigned int num_points = endPtsOfContours[num_contours - 1] + 1;

src/hb-ot-var-gvar-table.hh

diff --git a/src/hb-ot-var-gvar-table.hh b/src/hb-ot-var-gvar-table.hh
index 510174c..666b308 100644
--- a/src/hb-ot-var-gvar-table.hh
+++ b/src/hb-ot-var-gvar-table.hh
@@ -80,20 +80,19 @@
 
 struct range_checker_t
 {
-  range_checker_t (const void *table_, unsigned int start_offset_, unsigned int end_offset_)
-    : table ((const char*) table_), start_offset (start_offset_), end_offset (end_offset_) {}
+  range_checker_t (const void *data_, unsigned int length_)
+    : data ((const char *) data_), length (length_) {}
 
   template <typename T>
-  bool in_range (const T *p) const
+  bool in_range (const T *p, unsigned int size = T::static_size) const
   {
-    return ((const char *) p) >= table + start_offset
-	&& ((const char *) p + T::static_size) <= table + end_offset;
+    return ((const char *) p) >= data
+	&& ((const char *) p + size) <= data + length;
   }
 
   protected:
-  const char *table;
-  const unsigned int start_offset;
-  const unsigned int end_offset;
+  const char *data;
+  const unsigned int length;
 };
 
 struct Tuple : UnsizedArrayOf<F2DOT14> {};
@@ -234,7 +233,7 @@
     {
       if (var_data->has_shared_point_numbers ())
       {
-	range_checker_t checker (var_data, 0, length);
+	range_checker_t checker (var_data, length);
 	const HBUINT8 *base = &(var_data+var_data->data);
 	const HBUINT8 *p = base;
 	if (!unpack_points (p, shared_indices, checker)) return false;
@@ -612,7 +611,7 @@
 	if (unlikely (!iterator.in_range (p, length)))
 	  return false;
 
-	range_checker_t checker (p, 0, length);
+	range_checker_t checker (p, length);
 	hb_vector_t<unsigned int> private_indices;
 	if (iterator.current_tuple->has_private_points () &&
 	    !GlyphVarData::unpack_points (p, private_indices, checker))