From f30faf854b9bf01da294547a1bc3660506d750db Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 8 Aug 2018 16:22:55 +0900
Subject: [PATCH] util: introduce memcmp_safe()

---
 src/basic/util.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/basic/util.h b/src/basic/util.h
index 42c262f598..308933ac90 100644
--- a/src/basic/util.h
+++ b/src/basic/util.h
@@ -112,9 +112,7 @@ static inline void qsort_r_safe(void *base, size_t nmemb, size_t size, int (*com
         qsort_r(base, nmemb, size, compar, userdata);
 }
 
-/**
- * Normal memcpy requires src to be nonnull. We do nothing if n is 0.
- */
+/* Normal memcpy requires src to be nonnull. We do nothing if n is 0. */
 static inline void memcpy_safe(void *dst, const void *src, size_t n) {
         if (n == 0)
                 return;
@@ -122,6 +120,15 @@ static inline void memcpy_safe(void *dst, const void *src, size_t n) {
         memcpy(dst, src, n);
 }
 
+/* Normal memcmp requires s1 and s2 to be nonnull. We do nothing if n is 0. */
+static inline int memcmp_safe(const void *s1, const void *s2, size_t n) {
+        if (n == 0)
+                return 0;
+        assert(s1);
+        assert(s2);
+        return memcmp(s1, s2, n);
+}
+
 int on_ac_power(void);
 
 #define memzero(x,l) (memset((x), 0, (l)))