1 files changed, 40 insertions, 3 deletions
diff --git a/thirdparty/harfbuzz/src/hb-buffer.cc b/thirdparty/harfbuzz/src/hb-buffer.cc
index fddda23304..57a5ae03ed 100644
--- a/thirdparty/harfbuzz/src/hb-buffer.cc
+++ b/thirdparty/harfbuzz/src/hb-buffer.cc
@@ -387,9 +387,11 @@ hb_buffer_t::clear_positions ()
   hb_memset (pos, 0, sizeof (pos[0]) * len);
 }
 
-void
+bool
 hb_buffer_t::sync ()
 {
+  bool ret = false;
+
   assert (have_output);
 
   assert (idx <= len);
@@ -403,12 +405,39 @@ hb_buffer_t::sync ()
     info = out_info;
   }
   len = out_len;
+  ret = true;
 
 reset:
   have_output = false;
   out_len = 0;
   out_info = info;
   idx = 0;
+
+  return ret;
+}
+
+int
+hb_buffer_t::sync_so_far ()
+{
+  bool had_output = have_output;
+  unsigned out_i = out_len;
+  unsigned i = idx;
+  unsigned old_idx = idx;
+
+  if (sync ())
+    idx = out_i;
+  else
+    idx = i;
+
+  if (had_output)
+  {
+    have_output = true;
+    out_len = idx;
+  }
+
+  assert (idx <= len);
+
+  return idx - old_idx;
 }
 
 bool
@@ -802,7 +831,7 @@ hb_buffer_set_user_data (hb_buffer_t        *buffer,
  * Since: 0.9.2
  **/
 void *
-hb_buffer_get_user_data (hb_buffer_t        *buffer,
+hb_buffer_get_user_data (const hb_buffer_t  *buffer,
 			 hb_user_data_key_t *key)
 {
   return hb_object_get_user_data (buffer, key);
@@ -2090,8 +2119,16 @@ hb_buffer_set_message_func (hb_buffer_t *buffer,
 bool
 hb_buffer_t::message_impl (hb_font_t *font, const char *fmt, va_list ap)
 {
+  assert (!have_output || (out_info == info && out_len == idx));
+
+  message_depth++;
+
   char buf[100];
   vsnprintf (buf, sizeof (buf), fmt, ap);
-  return (bool) this->message_func (this, font, buf, this->message_data);
+  bool ret = (bool) this->message_func (this, font, buf, this->message_data);
+
+  message_depth--;
+
+  return ret;
 }
 #endif