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