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- // Copyright 2018 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/memory/shared_memory_mapping.h"
- #include <cstdint>
- #include <utility>
- #include "base/bits.h"
- #include "base/logging.h"
- #include "base/memory/shared_memory_security_policy.h"
- #include "base/memory/shared_memory_tracker.h"
- #include "base/system/sys_info.h"
- #include "base/unguessable_token.h"
- #include "build/build_config.h"
- namespace base {
- SharedMemoryMapping::SharedMemoryMapping() = default;
- SharedMemoryMapping::SharedMemoryMapping(SharedMemoryMapping&& mapping) noexcept
- : mapped_span_(std::exchange(mapping.mapped_span_, span<uint8_t>())),
- size_(mapping.size_),
- guid_(mapping.guid_),
- mapper_(mapping.mapper_) {}
- SharedMemoryMapping& SharedMemoryMapping::operator=(
- SharedMemoryMapping&& mapping) noexcept {
- Unmap();
- mapped_span_ = std::exchange(mapping.mapped_span_, span<uint8_t>());
- size_ = mapping.size_;
- guid_ = mapping.guid_;
- mapper_ = mapping.mapper_;
- return *this;
- }
- SharedMemoryMapping::~SharedMemoryMapping() {
- Unmap();
- }
- SharedMemoryMapping::SharedMemoryMapping(span<uint8_t> mapped_span,
- size_t size,
- const UnguessableToken& guid,
- SharedMemoryMapper* mapper)
- : mapped_span_(mapped_span), size_(size), guid_(guid), mapper_(mapper) {
- // Note: except on Windows, `mapped_span_.size() == size_`.
- SharedMemoryTracker::GetInstance()->IncrementMemoryUsage(*this);
- }
- void SharedMemoryMapping::Unmap() {
- if (!IsValid())
- return;
- SharedMemorySecurityPolicy::ReleaseReservationForMapping(size_);
- SharedMemoryTracker::GetInstance()->DecrementMemoryUsage(*this);
- SharedMemoryMapper* mapper = mapper_;
- if (!mapper)
- mapper = SharedMemoryMapper::GetDefaultInstance();
- // The backing mapper expects offset to be aligned to
- // `SysInfo::VMAllocationGranularity()`, so replicate the alignment that was
- // done when originally mapping in the region.
- uint8_t* aligned_data =
- bits::AlignDown(mapped_span_.data(), SysInfo::VMAllocationGranularity());
- size_t adjusted_size =
- mapped_span_.size() +
- static_cast<size_t>(mapped_span_.data() - aligned_data);
- span<uint8_t> span_to_unmap = make_span(aligned_data, adjusted_size);
- mapper->Unmap(span_to_unmap);
- }
- ReadOnlySharedMemoryMapping::ReadOnlySharedMemoryMapping() = default;
- ReadOnlySharedMemoryMapping::ReadOnlySharedMemoryMapping(
- ReadOnlySharedMemoryMapping&&) noexcept = default;
- ReadOnlySharedMemoryMapping& ReadOnlySharedMemoryMapping::operator=(
- ReadOnlySharedMemoryMapping&&) noexcept = default;
- ReadOnlySharedMemoryMapping::ReadOnlySharedMemoryMapping(
- span<uint8_t> mapped_span,
- size_t size,
- const UnguessableToken& guid,
- SharedMemoryMapper* mapper)
- : SharedMemoryMapping(mapped_span, size, guid, mapper) {}
- WritableSharedMemoryMapping::WritableSharedMemoryMapping() = default;
- WritableSharedMemoryMapping::WritableSharedMemoryMapping(
- WritableSharedMemoryMapping&&) noexcept = default;
- WritableSharedMemoryMapping& WritableSharedMemoryMapping::operator=(
- WritableSharedMemoryMapping&&) noexcept = default;
- WritableSharedMemoryMapping::WritableSharedMemoryMapping(
- span<uint8_t> mapped_span,
- size_t size,
- const UnguessableToken& guid,
- SharedMemoryMapper* mapper)
- : SharedMemoryMapping(mapped_span, size, guid, mapper) {}
- } // namespace base
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