| // Copyright 2015 The BoringSSL Authors |
| // |
| // 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 |
| // |
| // https://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. |
| |
| #include "internal.h" |
| |
| #include <assert.h> |
| #include <stdlib.h> |
| |
| |
| // See comment above the typedef of CRYPTO_refcount_t about these tests. |
| static_assert(alignof(CRYPTO_refcount_t) == alignof(CRYPTO_atomic_u32), |
| "CRYPTO_refcount_t does not match CRYPTO_atomic_u32 alignment"); |
| static_assert(sizeof(CRYPTO_refcount_t) == sizeof(CRYPTO_atomic_u32), |
| "CRYPTO_refcount_t does not match CRYPTO_atomic_u32 size"); |
| |
| static_assert((CRYPTO_refcount_t)-1 == CRYPTO_REFCOUNT_MAX, |
| "CRYPTO_REFCOUNT_MAX is incorrect"); |
| |
| void CRYPTO_refcount_inc(CRYPTO_refcount_t *in_count) { |
| CRYPTO_atomic_u32 *count = (CRYPTO_atomic_u32 *)in_count; |
| uint32_t expected = CRYPTO_atomic_load_u32(count); |
| |
| while (expected != CRYPTO_REFCOUNT_MAX) { |
| uint32_t new_value = expected + 1; |
| if (CRYPTO_atomic_compare_exchange_weak_u32(count, &expected, new_value)) { |
| break; |
| } |
| } |
| } |
| |
| int CRYPTO_refcount_dec_and_test_zero(CRYPTO_refcount_t *in_count) { |
| CRYPTO_atomic_u32 *count = (CRYPTO_atomic_u32 *)in_count; |
| uint32_t expected = CRYPTO_atomic_load_u32(count); |
| |
| for (;;) { |
| if (expected == 0) { |
| abort(); |
| } else if (expected == CRYPTO_REFCOUNT_MAX) { |
| return 0; |
| } else { |
| const uint32_t new_value = expected - 1; |
| if (CRYPTO_atomic_compare_exchange_weak_u32(count, &expected, |
| new_value)) { |
| return new_value == 0; |
| } |
| } |
| } |
| } |