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- // Copyright 2019 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/allocator/partition_allocator/random.h"
- #include <type_traits>
- #include "base/allocator/partition_allocator/partition_alloc_base/rand_util.h"
- #include "base/allocator/partition_allocator/partition_alloc_base/thread_annotations.h"
- #include "base/allocator/partition_allocator/partition_lock.h"
- namespace partition_alloc {
- class RandomGenerator {
- public:
- constexpr RandomGenerator() {}
- uint32_t RandomValue() {
- ::partition_alloc::internal::ScopedGuard guard(lock_);
- return GetGenerator()->RandUint32();
- }
- void SeedForTesting(uint64_t seed) {
- ::partition_alloc::internal::ScopedGuard guard(lock_);
- GetGenerator()->ReseedForTesting(seed);
- }
- private:
- ::partition_alloc::internal::Lock lock_ = {};
- bool initialized_ PA_GUARDED_BY(lock_) = false;
- union {
- internal::base::InsecureRandomGenerator instance_ PA_GUARDED_BY(lock_);
- uint8_t instance_buffer_[sizeof(
- internal::base::InsecureRandomGenerator)] PA_GUARDED_BY(lock_) = {};
- };
- internal::base::InsecureRandomGenerator* GetGenerator()
- PA_EXCLUSIVE_LOCKS_REQUIRED(lock_) {
- if (!initialized_) {
- new (instance_buffer_) internal::base::InsecureRandomGenerator();
- initialized_ = true;
- }
- return &instance_;
- }
- };
- // Note: this is redundant, since the anonymous union is incompatible with a
- // non-trivial default destructor. Not meant to be destructed anyway.
- static_assert(std::is_trivially_destructible<RandomGenerator>::value, "");
- namespace {
- RandomGenerator g_generator = {};
- } // namespace
- namespace internal {
- uint32_t RandomValue() {
- return g_generator.RandomValue();
- }
- } // namespace internal
- void SetMmapSeedForTesting(uint64_t seed) {
- return g_generator.SeedForTesting(seed);
- }
- } // namespace partition_alloc
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