From 849bdb0d24902cbbafada9177713d83791b00e9d Mon Sep 17 00:00:00 2001
From: Garret Rieger <grieger@google.com>
Date: Wed, 19 Jul 2017 17:35:13 -0700
Subject: [PATCH] Fix a crash in the woff2 encoder when it encounters a loca
 table with a length of zero.

---
 src/font.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/font.cc b/src/font.cc
index fc496e0..8dc1043 100644
--- a/src/font.cc
+++ b/src/font.cc
@@ -331,8 +331,11 @@ int NumGlyphs(const Font& font) {
     return 0;
   }
   int index_fmt = IndexFormat(font);
-  int num_glyphs = (loca_table->length / (index_fmt == 0 ? 2 : 4)) - 1;
-  return num_glyphs;
+  int loca_record_size = (index_fmt == 0 ? 2 : 4);
+  if (loca_table->length < loca_record_size) {
+    return 0;
+  }
+  return (loca_table->length / loca_record_size) - 1;
 }
 
 int IndexFormat(const Font& font) {