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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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.
*/
#pragma once
#include <signal.h>
#include "utils/s2n_result.h"
/* s2n-tls allows s2n_send and s2n_recv to be called concurrently.
* There are a handful of values that both methods need to access.
* However, C99 has no concept of concurrency, so provides no atomic data types.
*/
/* Wrap the underlying value in a struct to encourage developers to only use
* the provided atomic methods.
*/
typedef struct {
/* Traditionally, s2n-tls uses sig_atomic_t for its weak guarantee of
* atomicity for interrupts.
*/
sig_atomic_t val;
} s2n_atomic_flag;
/* These methods use compiler atomic built-ins if available and lock-free, but otherwise
* rely on setting / clearing a small value generally being atomic in practice.
*/
S2N_RESULT s2n_atomic_init();
void s2n_atomic_flag_set(s2n_atomic_flag *var);
void s2n_atomic_flag_clear(s2n_atomic_flag *var);
bool s2n_atomic_flag_test(s2n_atomic_flag *var);
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