From 670fec231d31bf7417de590efd3485f337a7330f Mon Sep 17 00:00:00 2001
From: Ebrahim Byagowi <ebrahim@gnu.org>
Date: Thu, 10 Oct 2019 09:21:08 +0330
Subject: [PATCH] Minor, add a zero length tolerant memset, hb_memset

---
 src/hb-algs.hh   | 10 +++++++++-
 src/hb-buffer.cc |  3 +--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/hb-algs.hh b/src/hb-algs.hh
index c57481bfe..042e1c20d 100644
--- a/src/hb-algs.hh
+++ b/src/hb-algs.hh
@@ -588,10 +588,18 @@ hb_memcmp (const void *a, const void *b, unsigned int len)
   /* It's illegal to pass NULL to memcmp(), even if len is zero.
    * So, wrap it.
    * https://sourceware.org/bugzilla/show_bug.cgi?id=23878 */
-  if (!len) return 0;
+  if (unlikely (!len)) return 0;
   return memcmp (a, b, len);
 }
 
+static inline void *
+hb_memset (void *s, int c, unsigned int n)
+{
+  /* It's illegal to pass NULL to memset(), even if n is zero. */
+  if (unlikely (!n)) return 0;
+  return memset (s, c, n);
+}
+
 static inline bool
 hb_unsigned_mul_overflows (unsigned int count, unsigned int size)
 {
diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index bb7f3c7c1..40ac55c1c 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -324,8 +324,7 @@ hb_buffer_t::clear_positions ()
   out_len = 0;
   out_info = info;
 
-  if (likely (len))
-    memset (pos, 0, sizeof (pos[0]) * len);
+  hb_memset (pos, 0, sizeof (pos[0]) * len);
 }
 
 void