From 95fcb946487f6a8ab346c635c66644acc0ee8dd2 Mon Sep 17 00:00:00 2001
From: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Date: Fri, 20 Jun 2014 18:29:15 +0200
Subject: [PATCH] Add explicit_bzero(3).

---
 libc/Makefile                  |  1 +
 libc/include/string.h          |  1 +
 libc/string/explicit_bzero.cpp | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 libc/string/explicit_bzero.cpp

diff --git a/libc/Makefile b/libc/Makefile
index daa68ab3..b891d061 100644
--- a/libc/Makefile
+++ b/libc/Makefile
@@ -184,6 +184,7 @@ stdlib/strtoull.o \
 stdlib/strtoul.o \
 stdlib/wcstombs.o \
 stdlib/wctomb.o \
+string/explicit_bzero.o \
 string/ffsll.o \
 string/ffsl.o \
 string/ffs.o \
diff --git a/libc/include/string.h b/libc/include/string.h
index 3bd814cb..5fbff141 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -124,6 +124,7 @@ size_t strxfrm_l(char* __restrict, const char* __restrict, size_t, locale_t);
 
 /* Functions copied from elsewhere. */
 #if __USE_SORTIX
+void explicit_bzero(void*, size_t);
 int ffsl(long int);
 void* memrchr(const void*, int, size_t);
 /* TODO: strcasecmp_l */
diff --git a/libc/string/explicit_bzero.cpp b/libc/string/explicit_bzero.cpp
new file mode 100644
index 00000000..a603e027
--- /dev/null
+++ b/libc/string/explicit_bzero.cpp
@@ -0,0 +1,34 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2014.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    The Sortix C Library is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    string/explicit_bzero.cpp
+    Initializes a region of memory to a byte value in a manner that is not
+    optimized away by the compiler.
+
+*******************************************************************************/
+
+#include <string.h>
+
+// TODO: Employ special compiler support to ensure this is not optimized away.
+extern "C" void explicit_bzero(void* dest_ptr, size_t size)
+{
+	volatile unsigned char* dest = (volatile unsigned char*) dest_ptr;
+	for ( size_t i = 0; i < size; i++ )
+		dest[i] = 0;
+}