From b2a0d55fd6cdbeadb8c415304c15d0e30046ff3b Mon Sep 17 00:00:00 2001
From: Andrew Kozlik <42678794+andrewkozlik@users.noreply.github.com>
Date: Sat, 16 Feb 2019 16:03:46 +0100
Subject: [PATCH] memzero: automate the selection of the implementation (#196)

---
 memzero.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/memzero.c b/memzero.c
index 6fda421197..b3cb3f99c3 100644
--- a/memzero.c
+++ b/memzero.c
@@ -1,7 +1,43 @@
+#ifndef __STDC_WANT_LIB_EXT1__
+#define __STDC_WANT_LIB_EXT1__ 1 // C11's bounds-checking interface.
+#endif
 #include <string.h>
-#include <strings.h>
 
-// taken from https://github.com/jedisct1/libsodium/blob/1647f0d53ae0e370378a9195477e3df0a792408f/src/libsodium/sodium/utils.c#L102-L130
+#ifdef _WIN32
+#include <Windows.h>
+#endif
+
+#ifdef __unix__
+#include <strings.h>
+#include <sys/param.h>
+#endif
+
+// C11's bounds-checking interface.
+#if defined(__STDC_LIB_EXT1__)
+#define HAVE_MEMSET_S 1
+#endif
+
+// GNU C Library version 2.25 or later.
+#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 25)
+#define HAVE_EXPLICIT_BZERO 1
+#endif
+
+// FreeBSD version 11.0 or later.
+#if defined(__FreeBSD__) && __FreeBSD_version >= 1100037
+#define HAVE_EXPLICIT_BZERO 1
+#endif
+
+// OpenBSD version 5.5 or later.
+#if defined(__OpenBSD__) && OpenBSD >= 201405
+#define HAVE_EXPLICIT_BZERO 1
+#endif
+
+// NetBSD version 7.2 or later.
+#if defined(__NetBSD__) && __NetBSD_Version__ >= 702000000
+#define HAVE_EXPLICIT_MEMSET 1
+#endif
+
+// Adapted from https://github.com/jedisct1/libsodium/blob/1647f0d53ae0e370378a9195477e3df0a792408f/src/libsodium/sodium/utils.c#L102-L130
 
 void memzero(void *const pnt, const size_t len)
 {