Remove memset_s, not implemented on any machine I can test on and

problematic for requiring a special define before the first include of
string.h. Instead optionally call memset via a volatile function
pointer as a faster alternative to byte at a time writes.

Github 42, 45

1 files changed, 5 insertions, 7 deletions

diff --git a/src/lib/utils/zero_mem.cpp b/src/lib/utils/zero_mem.cpp
index d8c438435..1dbf6e213 100644
--- a/src/lib/utils/zero_mem.cpp
+++ b/src/lib/utils/zero_mem.cpp
@@ -1,6 +1,6 @@
-/*
+ /*
 * Zero Memory
-* (C) 2012 Jack Lloyd
+* (C) 2012,2015 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -9,9 +9,6 @@
 
 #if defined(BOTAN_TARGET_OS_HAS_RTLSECUREZEROMEMORY)
   #include <windows.h>
-#elif defined(BOTAN_TARGET_OS_HAS_MEMSET_S)
-  #define __STDC_WANT_LIB_EXT1__ 1
-  #include <string.h>
 #endif
 
 namespace Botan {
@@ -20,8 +17,9 @@ void zero_mem(void* ptr, size_t n)
    {
 #if defined(BOTAN_TARGET_OS_HAS_RTLSECUREZEROMEMORY)
    ::RtlSecureZeroMemory(ptr, n);
-#elif defined(BOTAN_TARGET_OS_HAS_MEMSET_S)
-   ::memset_s(ptr, n, 0, n);
+#elif defined(BOTAN_USE_VOLATILE_MEMSET) && (BOTAN_USE_VOLATILE_MEMSET == 1)
+   static void* (*const volatile memset_ptr)(void*, int, size_t) = memset;
+   (memset_ptr)(p, 0, n);
 #else
    volatile byte* p = reinterpret_cast<volatile byte*>(ptr);