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#ifndef __STDC_WANT_LIB_EXT1__
#define __STDC_WANT_LIB_EXT1__ 1
#endif
#include "ruby/missing.h"
#include <string.h>
#ifdef HAVE_MEMSET_S
# include <string.h>
#endif
#ifdef _WIN32
#include <windows.h>
#endif
/* Similar to bzero(), but has a guarantee not to be eliminated from compiler
optimization. */
/* OS support note:
* BSDs have explicit_bzero().
* macOS has memset_s().
* Windows has SecureZeroMemory() since XP.
* Linux has explicit_bzero() since glibc 2.25, musl libc 1.1.20.
*/
/*
* Following URL explains why memset_s is added to the standard.
* http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1381.pdf
*/
#ifndef FUNC_UNOPTIMIZED
# define FUNC_UNOPTIMIZED(x) x
#endif
#undef explicit_bzero
#ifndef HAVE_EXPLICIT_BZERO
#ifdef HAVE_EXPLICIT_MEMSET
void
explicit_bzero(void *b, size_t len)
{
(void)explicit_memset(b, 0, len);
}
#elif defined HAVE_MEMSET_S
void
explicit_bzero(void *b, size_t len)
{
memset_s(b, len, 0, len);
}
#elif defined SecureZeroMemory
void
explicit_bzero(void *b, size_t len)
{
SecureZeroMemory(b, len);
}
#elif defined HAVE_FUNC_WEAK
/* A weak function never be optimized away. Even if nobody uses it. */
WEAK(void ruby_explicit_bzero_hook_unused(void *buf, size_t len));
void
ruby_explicit_bzero_hook_unused(void *buf, size_t len)
{
}
void
explicit_bzero(void *b, size_t len)
{
memset(b, 0, len);
ruby_explicit_bzero_hook_unused(b, len);
}
#else /* Your OS have no capability. Sigh. */
FUNC_UNOPTIMIZED(void explicit_bzero(void *b, size_t len));
#undef explicit_bzero
void
explicit_bzero(void *b, size_t len)
{
/*
* volatile is not enough if the compiler has an LTO (link time
* optimization). At least, the standard provides no guarantee.
* However, gcc and major other compilers never optimize a volatile
* variable away. So, using volatile is practically ok.
*/
volatile char* p = (volatile char*)b;
while(len) {
*p = 0;
p++;
len--;
}
}
#endif
#endif /* HAVE_EXPLICIT_BZERO */
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