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/* Copyright (c) 2015, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include "internal.h"
#if defined(OPENSSL_C11_ATOMIC)
#include <assert.h>
#include <stdalign.h>
#include <stdatomic.h>
#include <stdlib.h>
#include <openssl/type_check.h>
/* See comment above the typedef of CRYPTO_refcount_t about these tests. */
static_assert(alignof(CRYPTO_refcount_t) == alignof(_Atomic CRYPTO_refcount_t),
"_Atomic alters the needed alignment of a reference count");
static_assert(sizeof(CRYPTO_refcount_t) == sizeof(_Atomic CRYPTO_refcount_t),
"_Atomic alters the size of a reference count");
static_assert((CRYPTO_refcount_t)-1 == CRYPTO_REFCOUNT_MAX,
"CRYPTO_REFCOUNT_MAX is incorrect");
void CRYPTO_refcount_inc(CRYPTO_refcount_t *in_count) {
_Atomic CRYPTO_refcount_t *count = (_Atomic CRYPTO_refcount_t *) in_count;
uint32_t expected = atomic_load(count);
while (expected != CRYPTO_REFCOUNT_MAX) {
uint32_t new_value = expected + 1;
if (atomic_compare_exchange_weak(count, &expected, new_value)) {
break;
}
}
}
int CRYPTO_refcount_dec_and_test_zero(CRYPTO_refcount_t *in_count) {
_Atomic CRYPTO_refcount_t *count = (_Atomic CRYPTO_refcount_t *)in_count;
uint32_t expected = atomic_load(count);
for (;;) {
if (expected == 0) {
abort();
} else if (expected == CRYPTO_REFCOUNT_MAX) {
return 0;
} else {
const uint32_t new_value = expected - 1;
if (atomic_compare_exchange_weak(count, &expected, new_value)) {
return new_value == 0;
}
}
}
}
#endif /* OPENSSL_C11_ATOMIC */
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