/*

 * Common and shared functions used by multiple modules in the Mbed TLS

 * library.

 *

 *  Copyright The Mbed TLS Contributors

 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later

 */

/*

 * Ensure gmtime_r is available even with -std=c99; must be defined before

 * config.h, which pulls in glibc's features.h. Harmless on other platforms.

 */

#if !defined(_POSIX_C_SOURCE)

#define _POSIX_C_SOURCE 200112L

#endif

#include "common.h"

#include "mbedtls/platform_util.h"

#include "mbedtls/platform.h"

#include "mbedtls/threading.h"

#include <stddef.h>

#include <string.h>

#if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)

/*

 * This implementation should never be optimized out by the compiler

 *

 * This implementation for mbedtls_platform_zeroize() was inspired from Colin

 * Percival's blog article at:

 *

 * http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html

 *

 * It uses a volatile function pointer to the standard memset(). Because the

 * pointer is volatile the compiler expects it to change at

 * any time and will not optimize out the call that could potentially perform

 * other operations on the input buffer instead of just setting it to 0.

 * Nevertheless, as pointed out by davidtgoldblatt on Hacker News

 * (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for

 * details), optimizations of the following form are still possible:

 *

 * if( memset_func != memset )

 *     memset_func( buf, 0, len );

 *

 * Note that it is extremely difficult to guarantee that

 * mbedtls_platform_zeroize() will not be optimized out by aggressive compilers

 * in a portable way. For this reason, Mbed TLS also provides the configuration

 * option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure

 * mbedtls_platform_zeroize() to use a suitable implementation for their

 * platform and needs.

 */

static void *(*const volatile memset_func)(void *, int, size_t) = memset;

void mbedtls_platform_zeroize(void *buf, size_t len)

{

    MBEDTLS_INTERNAL_VALIDATE(len == 0 || buf != NULL);

    if (len > 0) {

        memset_func(buf, 0, len);

    }

}

#endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */

#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)

#include <time.h>

#if !defined(_WIN32) && (defined(unix) || \

    defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \

    defined(__MACH__)) || defined(__midipix__))

#include <unistd.h>

#endif /* !_WIN32 && (unix || __unix || __unix__ ||

        * (__APPLE__ && __MACH__)) || __midipix__ */

#if !((defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L) ||     \

    (defined(_POSIX_THREAD_SAFE_FUNCTIONS) &&                     \

    _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L))

/*

 * This is a convenience shorthand macro to avoid checking the long

 * preprocessor conditions above. Ideally, we could expose this macro in

 * platform_util.h and simply use it in platform_util.c, threading.c and

 * threading.h. However, this macro is not part of the Mbed TLS public API, so

 * we keep it private by only defining it in this file

 */

#if !(defined(_WIN32) && !defined(EFIX64) && !defined(EFI32))

#define PLATFORM_UTIL_USE_GMTIME

#endif /* ! ( defined(_WIN32) && !defined(EFIX64) && !defined(EFI32) ) */

#endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \

             ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \

                _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */

struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt,

                                     struct tm *tm_buf)

{

#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)

    return (gmtime_s(tm_buf, tt) == 0) ? tm_buf : NULL;

#elif !defined(PLATFORM_UTIL_USE_GMTIME)

    return gmtime_r(tt, tm_buf);

#else

    struct tm *lt;

#if defined(MBEDTLS_THREADING_C)

    if (mbedtls_mutex_lock(&mbedtls_threading_gmtime_mutex) != 0) {

        return NULL;

    }

#endif /* MBEDTLS_THREADING_C */

    lt = gmtime(tt);

    if (lt != NULL) {

        memcpy(tm_buf, lt, sizeof(struct tm));

    }

#if defined(MBEDTLS_THREADING_C)

    if (mbedtls_mutex_unlock(&mbedtls_threading_gmtime_mutex) != 0) {

        return NULL;

    }

#endif /* MBEDTLS_THREADING_C */

    return (lt == NULL) ? NULL : tm_buf;

#endif /* _WIN32 && !EFIX64 && !EFI32 */

}

#endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */