1/* OPENBSD ORIGINAL: lib/libc/string/explicit_bzero.c */
2/*	$OpenBSD: explicit_bzero.c,v 1.1 2014/01/22 21:06:45 tedu Exp $ */
3/*
4 * Public domain.
5 * Written by Ted Unangst
6 */
7
8#include "includes.h"
9
10#include <string.h>
11
12/*
13 * explicit_bzero - don't let the compiler optimize away bzero
14 */
15
16#ifndef HAVE_EXPLICIT_BZERO
17
18#ifdef HAVE_MEMSET_S
19
20void
21explicit_bzero(void *p, size_t n)
22{
23	if (n == 0)
24		return;
25	(void)memset_s(p, n, 0, n);
26}
27
28#else /* HAVE_MEMSET_S */
29
30/*
31 * Indirect bzero through a volatile pointer to hopefully avoid
32 * dead-store optimisation eliminating the call.
33 */
34static void (* volatile ssh_bzero)(void *, size_t) = bzero;
35
36void
37explicit_bzero(void *p, size_t n)
38{
39	if (n == 0)
40		return;
41	/*
42	 * clang -fsanitize=memory needs to intercept memset-like functions
43	 * to correctly detect memory initialisation. Make sure one is called
44	 * directly since our indirection trick above successfully confuses it.
45	 */
46#if defined(__has_feature)
47# if __has_feature(memory_sanitizer)
48	memset(p, 0, n);
49# endif
50#endif
51
52	ssh_bzero(p, n);
53}
54
55#endif /* HAVE_MEMSET_S */
56
57#endif /* HAVE_EXPLICIT_BZERO */
58