205 lines
7.3 KiB
C
205 lines
7.3 KiB
C
/**
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* \file common.h
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*
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* \brief Utility macros for internal use in the library
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef MBEDTLS_LIBRARY_COMMON_H
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#define MBEDTLS_LIBRARY_COMMON_H
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#include "mbedtls/build_info.h"
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#include "alignment.h"
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#include <assert.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stddef.h>
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/** Helper to define a function as static except when building invasive tests.
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*
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* If a function is only used inside its own source file and should be
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* declared `static` to allow the compiler to optimize for code size,
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* but that function has unit tests, define it with
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* ```
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* MBEDTLS_STATIC_TESTABLE int mbedtls_foo(...) { ... }
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* ```
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* and declare it in a header in the `library/` directory with
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* ```
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* #if defined(MBEDTLS_TEST_HOOKS)
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* int mbedtls_foo(...);
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* #endif
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* ```
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*/
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#if defined(MBEDTLS_TEST_HOOKS)
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#define MBEDTLS_STATIC_TESTABLE
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#else
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#define MBEDTLS_STATIC_TESTABLE static
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#endif
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#if defined(MBEDTLS_TEST_HOOKS)
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extern void (*mbedtls_test_hook_test_fail)(const char *test, int line, const char *file);
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#define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST) \
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do { \
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if ((!(TEST)) && ((*mbedtls_test_hook_test_fail) != NULL)) \
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{ \
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(*mbedtls_test_hook_test_fail)( #TEST, __LINE__, __FILE__); \
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} \
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} while (0)
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#else
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#define MBEDTLS_TEST_HOOK_TEST_ASSERT(TEST)
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#endif /* defined(MBEDTLS_TEST_HOOKS) */
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/** \def ARRAY_LENGTH
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* Return the number of elements of a static or stack array.
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*
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* \param array A value of array (not pointer) type.
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*
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* \return The number of elements of the array.
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*/
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/* A correct implementation of ARRAY_LENGTH, but which silently gives
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* a nonsensical result if called with a pointer rather than an array. */
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#define ARRAY_LENGTH_UNSAFE(array) \
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(sizeof(array) / sizeof(*(array)))
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#if defined(__GNUC__)
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/* Test if arg and &(arg)[0] have the same type. This is true if arg is
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* an array but not if it's a pointer. */
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#define IS_ARRAY_NOT_POINTER(arg) \
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(!__builtin_types_compatible_p(__typeof__(arg), \
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__typeof__(&(arg)[0])))
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/* A compile-time constant with the value 0. If `const_expr` is not a
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* compile-time constant with a nonzero value, cause a compile-time error. */
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#define STATIC_ASSERT_EXPR(const_expr) \
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(0 && sizeof(struct { unsigned int STATIC_ASSERT : 1 - 2 * !(const_expr); }))
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/* Return the scalar value `value` (possibly promoted). This is a compile-time
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* constant if `value` is. `condition` must be a compile-time constant.
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* If `condition` is false, arrange to cause a compile-time error. */
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#define STATIC_ASSERT_THEN_RETURN(condition, value) \
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(STATIC_ASSERT_EXPR(condition) ? 0 : (value))
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#define ARRAY_LENGTH(array) \
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(STATIC_ASSERT_THEN_RETURN(IS_ARRAY_NOT_POINTER(array), \
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ARRAY_LENGTH_UNSAFE(array)))
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#else
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/* If we aren't sure the compiler supports our non-standard tricks,
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* fall back to the unsafe implementation. */
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#define ARRAY_LENGTH(array) ARRAY_LENGTH_UNSAFE(array)
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#endif
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/** Allow library to access its structs' private members.
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*
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* Although structs defined in header files are publicly available,
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* their members are private and should not be accessed by the user.
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*/
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#define MBEDTLS_ALLOW_PRIVATE_ACCESS
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/** Return an offset into a buffer.
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*
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* This is just the addition of an offset to a pointer, except that this
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* function also accepts an offset of 0 into a buffer whose pointer is null.
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* (`p + n` has undefined behavior when `p` is null, even when `n == 0`.
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* A null pointer is a valid buffer pointer when the size is 0, for example
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* as the result of `malloc(0)` on some platforms.)
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*
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* \param p Pointer to a buffer of at least n bytes.
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* This may be \p NULL if \p n is zero.
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* \param n An offset in bytes.
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* \return Pointer to offset \p n in the buffer \p p.
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* Note that this is only a valid pointer if the size of the
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* buffer is at least \p n + 1.
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*/
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static inline unsigned char *mbedtls_buffer_offset(
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unsigned char *p, size_t n)
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{
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return p == NULL ? NULL : p + n;
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}
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/** Return an offset into a read-only buffer.
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*
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* Similar to mbedtls_buffer_offset(), but for const pointers.
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*
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* \param p Pointer to a buffer of at least n bytes.
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* This may be \p NULL if \p n is zero.
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* \param n An offset in bytes.
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* \return Pointer to offset \p n in the buffer \p p.
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* Note that this is only a valid pointer if the size of the
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* buffer is at least \p n + 1.
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*/
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static inline const unsigned char *mbedtls_buffer_offset_const(
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const unsigned char *p, size_t n)
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{
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return p == NULL ? NULL : p + n;
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}
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/**
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* Perform a fast block XOR operation, such that
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* r[i] = a[i] ^ b[i] where 0 <= i < n
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*
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* \param r Pointer to result (buffer of at least \p n bytes). \p r
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* may be equal to either \p a or \p b, but behaviour when
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* it overlaps in other ways is undefined.
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* \param a Pointer to input (buffer of at least \p n bytes)
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* \param b Pointer to input (buffer of at least \p n bytes)
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* \param n Number of bytes to process.
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*/
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inline void mbedtls_xor(unsigned char *r, const unsigned char *a, const unsigned char *b, size_t n)
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{
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size_t i = 0;
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#if defined(MBEDTLS_EFFICIENT_UNALIGNED_ACCESS)
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for (; (i + 4) <= n; i += 4) {
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uint32_t x = mbedtls_get_unaligned_uint32(a + i) ^ mbedtls_get_unaligned_uint32(b + i);
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mbedtls_put_unaligned_uint32(r + i, x);
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}
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#endif
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for (; i < n; i++) {
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r[i] = a[i] ^ b[i];
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}
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}
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/* Fix MSVC C99 compatible issue
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* MSVC support __func__ from visual studio 2015( 1900 )
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* Use MSVC predefine macro to avoid name check fail.
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*/
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#if (defined(_MSC_VER) && (_MSC_VER <= 1900))
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#define /*no-check-names*/ __func__ __FUNCTION__
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#endif
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/* Define `asm` for compilers which don't define it. */
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/* *INDENT-OFF* */
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#ifndef asm
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#define asm __asm__
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#endif
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/* *INDENT-ON* */
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/* Always provide a static assert macro, so it can be used unconditionally.
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* It will expand to nothing on some systems.
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* Can be used outside functions (but don't add a trailing ';' in that case:
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* the semicolon is included here to avoid triggering -Wextra-semi when
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* MBEDTLS_STATIC_ASSERT() expands to nothing).
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* Can't use the C11-style `defined(static_assert)` on FreeBSD, since it
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* defines static_assert even with -std=c99, but then complains about it.
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*/
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#if defined(static_assert) && !defined(__FreeBSD__)
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#define MBEDTLS_STATIC_ASSERT(expr, msg) static_assert(expr, msg);
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#else
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#define MBEDTLS_STATIC_ASSERT(expr, msg)
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#endif
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#endif /* MBEDTLS_LIBRARY_COMMON_H */
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