/* Erasure of sensitive data, generic implementation.

   Copyright (C) 2016-2020 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU 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 2.1 of the License, or (at your option) any later version.

   The GNU 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 GNU C Library; if not, see

   <https://www.gnu.org/licenses/>.  */

/* An assembler implementation of explicit_bzero can be created as an

   assembler alias of an optimized bzero implementation.

   Architecture-specific implementations also need to define

   __explicit_bzero_chk.  */

#if !_LIBC

# include <config.h>

#endif

/* memset_s need this define */

#if HAVE_MEMSET_S

# define __STDC_WANT_LIB_EXT1__ 1

#endif

#include <string.h>

#if defined _WIN32 && !defined __CYGWIN__

# define  WIN32_LEAN_AND_MEAN

# include <windows.h>

#endif

#if _LIBC

/* glibc-internal users use __explicit_bzero_chk, and explicit_bzero

   redirects to that.  */

# undef explicit_bzero

#endif

/* Set LEN bytes of S to 0.  The compiler will not delete a call to

   this function, even if S is dead after the call.  */

void

explicit_bzero (void *s, size_t len)

{

#if defined _WIN32 && !defined __CYGWIN__

  (void) SecureZeroMemory (s, len);

#elif HAVE_EXPLICIT_MEMSET

  explicit_memset (s, '\0', len);

#elif HAVE_MEMSET_S

  (void) memset_s (s, len, '\0', len);

#else

  memset (s, '\0', len);

# if defined __GNUC__ && !defined __clang__

  /* Compiler barrier.  */

  asm volatile ("" ::: "memory");

# endif

#endif

}