[subset] hook up the repacker to run if offset overflows are encountered during subsetting.

src/hb-serialize.hh

@@ -136,7 +136,14 @@ struct hb_serialize_context_t
 
   template <typename T1, typename T2>
   bool check_equal (T1 &&v1, T2 &&v2)
-  { return check_success ((long long) v1 == (long long) v2); }
+  {
+    if ((long long) v1 != (long long) v2)
+    {
+      err_offset_overflow ();
+      return false;
+    }
+    return true;
+  }
 
   template <typename T1, typename T2>
   bool check_assign (T1 &v1, T2 &&v2)
@@ -400,6 +407,7 @@ struct hb_serialize_context_t
 
   /* Following two functions exist to allow setting breakpoint on. */
   void err_ran_out_of_room () { this->ran_out_of_room = true; }
+  void err_offset_overflow () { this->offset_overflow = true; }
   void err_other_error () { this->successful = false; }
 
   template <typename Type>
@@ -520,7 +528,7 @@ struct hb_serialize_context_t
 			   (char *) b.arrayZ, free);
   }
 
-  const hb_vector_t<object_t *>& object_graph()
+  const hb_vector_t<object_t *>& object_graph() const
   { return packed; }
 
   private:
@@ -537,6 +545,7 @@ struct hb_serialize_context_t
   unsigned int debug_depth;
   bool successful;
   bool ran_out_of_room;
+  bool offset_overflow;
 
   private:
 

src/hb-subset.cc

@@ -50,6 +50,7 @@
 #include "hb-ot-layout-gpos-table.hh"
 #include "hb-ot-var-gvar-table.hh"
 #include "hb-ot-var-hvar-table.hh"
+#include "hb-repacker.hh"
 
 
 static unsigned
@@ -64,6 +65,32 @@ _plan_estimate_subset_table_size (hb_subset_plan_t *plan, unsigned table_len)
   return 512 + (unsigned) (table_len * sqrt ((double) dst_glyphs / src_glyphs));
 }
 
+/*
+ * Repack the serialization buffer if any offset overflows exist.
+ */
+static hb_blob_t*
+_repack (const hb_serialize_context_t& c)
+{
+  if (!c.offset_overflow)
+    return c.copy_blob ();
+
+  hb_vector_t<char> buf;
+  int buf_size = c.end - c.start;
+  if (unlikely (!buf.alloc (buf_size)))
+    return nullptr;
+
+  hb_serialize_context_t repacked ((void *) buf, buf_size);
+  hb_resolve_overflows (c.object_graph (), &repacked);
+
+  if (unlikely (repacked.ran_out_of_room || repacked.in_error () || repacked.offset_overflow))
+    // TODO(garretrieger): refactor so we can share the resize/retry logic with the subset
+    //                     portion.
+    return nullptr;
+
+  return repacked.copy_blob ();
+}
+
+
 template<typename TableType>
 static bool
 _subset (hb_subset_plan_t *plan)
@@ -111,7 +138,8 @@ _subset (hb_subset_plan_t *plan)
     {
       if (needed)
       {
-	hb_blob_t *dest_blob = serializer.copy_blob ();
+	hb_blob_t *dest_blob = _repack (serializer);
+        if (!dest_blob) return false;
 	DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c final subset table size: %u bytes.", HB_UNTAG (tag), dest_blob->length);
 	result = c.plan->add_table (tag, dest_blob);
 	hb_blob_destroy (dest_blob);