mbedtls/library/threading.c
Gilles Peskine 39a1a26d0b Explain the usage of is_valid in pthread mutexes
Document the usage inside the library, and relate it with how it's
additionally used in the test code.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2021-02-22 19:24:03 +01:00

188 lines
6.1 KiB
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
* 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 */