platform_shared_memory_mapping.cc 2.9 KB

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  1. // Copyright 2018 The Chromium Authors. All rights reserved.
  2. // Use of this source code is governed by a BSD-style license that can be
  3. // found in the LICENSE file.
  4. #include "mojo/core/platform_shared_memory_mapping.h"
  5. #include <type_traits>
  6. #include <utility>
  7. #include "base/check.h"
  8. #include "base/memory/read_only_shared_memory_region.h"
  9. #include "base/memory/unsafe_shared_memory_region.h"
  10. #include "base/memory/writable_shared_memory_region.h"
  11. #include "build/build_config.h"
  12. namespace mojo {
  13. namespace core {
  14. PlatformSharedMemoryMapping::PlatformSharedMemoryMapping(
  15. base::subtle::PlatformSharedMemoryRegion* region,
  16. size_t offset,
  17. size_t length) {
  18. switch (region->GetMode()) {
  19. case base::subtle::PlatformSharedMemoryRegion::Mode::kReadOnly: {
  20. auto read_only_region =
  21. base::ReadOnlySharedMemoryRegion::Deserialize(std::move(*region));
  22. mapping_ = read_only_region.MapAt(offset, length);
  23. *region = base::ReadOnlySharedMemoryRegion::TakeHandleForSerialization(
  24. std::move(read_only_region));
  25. return;
  26. }
  27. case base::subtle::PlatformSharedMemoryRegion::Mode::kUnsafe: {
  28. auto unsafe_region =
  29. base::UnsafeSharedMemoryRegion::Deserialize(std::move(*region));
  30. mapping_ = unsafe_region.MapAt(offset, length);
  31. *region = base::UnsafeSharedMemoryRegion::TakeHandleForSerialization(
  32. std::move(unsafe_region));
  33. return;
  34. }
  35. case base::subtle::PlatformSharedMemoryRegion::Mode::kWritable: {
  36. auto writable_region =
  37. base::WritableSharedMemoryRegion::Deserialize(std::move(*region));
  38. mapping_ = writable_region.MapAt(offset, length);
  39. *region = base::WritableSharedMemoryRegion::TakeHandleForSerialization(
  40. std::move(writable_region));
  41. return;
  42. }
  43. }
  44. CHECK(false);
  45. }
  46. PlatformSharedMemoryMapping::~PlatformSharedMemoryMapping() = default;
  47. bool PlatformSharedMemoryMapping::IsValid() const {
  48. return absl::visit(
  49. [](const auto& member) {
  50. using T = std::decay_t<decltype(member)>;
  51. if constexpr (std::is_same_v<T, absl::monostate>) {
  52. return false;
  53. } else {
  54. return member.IsValid();
  55. }
  56. },
  57. mapping_);
  58. }
  59. void* PlatformSharedMemoryMapping::GetBase() const {
  60. return absl::visit(
  61. [](const auto& member) -> void* {
  62. using T = std::decay_t<decltype(member)>;
  63. if constexpr (std::is_same_v<T, absl::monostate>) {
  64. return nullptr;
  65. } else {
  66. return const_cast<void*>(member.memory());
  67. }
  68. },
  69. mapping_);
  70. }
  71. size_t PlatformSharedMemoryMapping::GetLength() const {
  72. return absl::visit(
  73. [](const auto& member) -> size_t {
  74. using T = std::decay_t<decltype(member)>;
  75. if constexpr (std::is_same_v<T, absl::monostate>) {
  76. return 0;
  77. } else {
  78. return member.size();
  79. }
  80. },
  81. mapping_);
  82. }
  83. } // namespace core
  84. } // namespace mojo