From ffde3c9f9effcd2b47f5fd76df45551e68c0b1ec Mon Sep 17 00:00:00 2001
From: Philip Withnall <philip@tecnocode.co.uk>
Date: Wed, 8 Feb 2017 21:56:57 +0000
Subject: [PATCH] hb-font: Fix a potentially undefined use of memcmp() (#413)
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While it’s fine to call memcmp(x, 0, 0) in practice, the C99 standard
explicitly says that this is not allowed: even if the length is zero,
the pointer arguments must be valid.

http://stackoverflow.com/a/16363034

Coverity ID: 141178

Signed-off-by: Philip Withnall <withnall@endlessm.com>
---
 src/hb-font.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/hb-font.cc b/src/hb-font.cc
index a08766f5..e900bd3f 100644
--- a/src/hb-font.cc
+++ b/src/hb-font.cc
@@ -1596,7 +1596,8 @@ _hb_font_adopt_var_coords_normalized (hb_font_t *font,
 				      unsigned int coords_length)
 {
   if (font->num_coords == coords_length &&
-      0 == memcmp (font->coords, coords, coords_length * sizeof (coords[0])))
+      (coords_length == 0 ||
+       0 == memcmp (font->coords, coords, coords_length * sizeof (coords[0]))))
   {
     free (coords);
     return;
-- 
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