library/threading.c

/*
 *  Threading abstraction layer
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

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

#if defined(MBEDTLS_THREADING_C)

#    include "mbedtls/threading.h"

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

#        if !defined(_WIN32) &&                                       \
            (defined(unix) || defined(__unix) || defined(__unix__) || \
             (defined(__APPLE__) && defined(__MACH__)))
#            include <unistd.h>
#        endif /* !_WIN32 && (unix || __unix || __unix__ || \
                * (__APPLE__ && __MACH__)) */

#        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 THREADING_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 ) ) */

#    endif /* MBEDTLS_HAVE_TIME_DATE && !MBEDTLS_PLATFORM_GMTIME_R_ALT */

#    if defined(MBEDTLS_THREADING_PTHREAD)
static void threading_mutex_init_pthread(mbedtls_threading_mutex_t *mutex)
{
    if (mutex == NULL)
        return;

    /* A nonzero value of is_valid indicates a successfully initialized
     * mutex. This is a workaround for not being able to return an error
     * code for this function. The lock/unlock functions return an error
     * if is_valid is nonzero. The Mbed TLS unit test code uses this field
     * to distinguish more states of the mutex; see
     * tests/src/threading_helpers for details. */
    mutex->is_valid = pthread_mutex_init(&mutex->mutex, NULL) == 0;
}

static void threading_mutex_free_pthread(mbedtls_threading_mutex_t *mutex)
{
    if (mutex == NULL || !mutex->is_valid)
        return;

    (void)pthread_mutex_destroy(&mutex->mutex);
    mutex->is_valid = 0;
}

static int threading_mutex_lock_pthread(mbedtls_threading_mutex_t *mutex)
{
    if (mutex == NULL || !mutex->is_valid)
        return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA;

    if (pthread_mutex_lock(&mutex->mutex) != 0)
        return MBEDTLS_ERR_THREADING_MUTEX_ERROR;

    return 0;
}

static int threading_mutex_unlock_pthread(mbedtls_threading_mutex_t *mutex)
{
    if (mutex == NULL || !mutex->is_valid)
        return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA;

    if (pthread_mutex_unlock(&mutex->mutex) != 0)
        return MBEDTLS_ERR_THREADING_MUTEX_ERROR;

    return 0;
}

void (*mbedtls_mutex_init)(mbedtls_threading_mutex_t *) =
    threading_mutex_init_pthread;
void (*mbedtls_mutex_free)(mbedtls_threading_mutex_t *) =
    threading_mutex_free_pthread;
int (*mbedtls_mutex_lock)(mbedtls_threading_mutex_t *) =
    threading_mutex_lock_pthread;
int (*mbedtls_mutex_unlock)(mbedtls_threading_mutex_t *) =
    threading_mutex_unlock_pthread;

/*
 * With phtreads we can statically initialize mutexes
 */
#        define MUTEX_INIT = { PTHREAD_MUTEX_INITIALIZER, 1 }

#    endif /* MBEDTLS_THREADING_PTHREAD */

#    if defined(MBEDTLS_THREADING_ALT)
static int threading_mutex_fail(mbedtls_threading_mutex_t *mutex)
{
    ((void)mutex);
    return MBEDTLS_ERR_THREADING_BAD_INPUT_DATA;
}
static void threading_mutex_dummy(mbedtls_threading_mutex_t *mutex)
{
    ((void)mutex);
    return;
}

void (*mbedtls_mutex_init)(mbedtls_threading_mutex_t *) = threading_mutex_dummy;
void (*mbedtls_mutex_free)(mbedtls_threading_mutex_t *) = threading_mutex_dummy;
int (*mbedtls_mutex_lock)(mbedtls_threading_mutex_t *) = threading_mutex_fail;
int (*mbedtls_mutex_unlock)(mbedtls_threading_mutex_t *) = threading_mutex_fail;

/*
 * Set functions pointers and initialize global mutexes
 */
void mbedtls_threading_set_alt(void (*mutex_init)(mbedtls_threading_mutex_t *),
                               void (*mutex_free)(mbedtls_threading_mutex_t *),
                               int (*mutex_lock)(mbedtls_threading_mutex_t *),
                               int (*mutex_unlock)(mbedtls_threading_mutex_t *))
{
    mbedtls_mutex_init = mutex_init;
    mbedtls_mutex_free = mutex_free;
    mbedtls_mutex_lock = mutex_lock;
    mbedtls_mutex_unlock = mutex_unlock;

#        if defined(MBEDTLS_FS_IO)
    mbedtls_mutex_init(&mbedtls_threading_readdir_mutex);
#        endif
#        if defined(THREADING_USE_GMTIME)
    mbedtls_mutex_init(&mbedtls_threading_gmtime_mutex);
#        endif
}

/*
 * Free global mutexes
 */
void mbedtls_threading_free_alt(void)
{
#        if defined(MBEDTLS_FS_IO)
    mbedtls_mutex_free(&mbedtls_threading_readdir_mutex);
#        endif
#        if defined(THREADING_USE_GMTIME)
    mbedtls_mutex_free(&mbedtls_threading_gmtime_mutex);
#        endif
}
#    endif /* MBEDTLS_THREADING_ALT */

/*
 * Define global mutexes
 */
#    ifndef MUTEX_INIT
#        define MUTEX_INIT
#    endif
#    if defined(MBEDTLS_FS_IO)
mbedtls_threading_mutex_t mbedtls_threading_readdir_mutex MUTEX_INIT;
#    endif
#    if defined(THREADING_USE_GMTIME)
mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex MUTEX_INIT;
#    endif

#endif /* MBEDTLS_THREADING_C */