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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "mojo/core/ipcz_driver/shared_buffer_mapping.h"
#include <utility>
#include "base/memory/read_only_shared_memory_region.h"
#include "base/memory/unsafe_shared_memory_region.h"
#include "base/memory/writable_shared_memory_region.h"
namespace mojo::core::ipcz_driver {
namespace {
// Wraps and unwraps a raw PlatformSharedMemoryRegion as some more specific base
// region type to produce an appropriate SharedMemoryMapping.
template <typename RegionType>
std::unique_ptr<base::SharedMemoryMapping> MapRegion(
base::subtle::PlatformSharedMemoryRegion& region,
size_t offset,
size_t size,
void** memory) {
auto r = RegionType::Deserialize(std::move(region));
typename RegionType::MappingType m = r.MapAt(offset, size);
region = RegionType::TakeHandleForSerialization(std::move(r));
if (!m.IsValid()) {
return nullptr;
}
// TODO(crbug.com/355607629): This function should give back a span instead of
// an unbounded pointer.
*memory = const_cast<uint8_t*>(m.data());
return std::make_unique<typename RegionType::MappingType>(std::move(m));
}
std::unique_ptr<base::SharedMemoryMapping> MapPlatformRegion(
base::subtle::PlatformSharedMemoryRegion& region,
size_t offset,
size_t size,
void** memory) {
using Mode = base::subtle::PlatformSharedMemoryRegion::Mode;
switch (region.GetMode()) {
case Mode::kReadOnly:
return MapRegion<base::ReadOnlySharedMemoryRegion>(region, offset, size,
memory);
case Mode::kWritable:
return MapRegion<base::WritableSharedMemoryRegion>(region, offset, size,
memory);
case Mode::kUnsafe:
return MapRegion<base::UnsafeSharedMemoryRegion>(region, offset, size,
memory);
}
return nullptr;
}
} // namespace
SharedBufferMapping::SharedBufferMapping(
std::unique_ptr<base::SharedMemoryMapping> mapping,
void* memory)
: mapping_(std::move(mapping)), memory_(memory) {}
SharedBufferMapping::~SharedBufferMapping() = default;
// static
scoped_refptr<SharedBufferMapping> SharedBufferMapping::Create(
base::subtle::PlatformSharedMemoryRegion& region,
size_t offset,
size_t size) {
void* memory;
auto mapping = MapPlatformRegion(region, offset, size, &memory);
if (!mapping) {
return nullptr;
}
return base::MakeRefCounted<SharedBufferMapping>(std::move(mapping), memory);
}
// static
scoped_refptr<SharedBufferMapping> SharedBufferMapping::Create(
base::subtle::PlatformSharedMemoryRegion& region) {
void* memory;
auto mapping = MapPlatformRegion(region, 0, region.GetSize(), &memory);
if (!mapping) {
return nullptr;
}
return base::MakeRefCounted<SharedBufferMapping>(std::move(mapping), memory);
}
void SharedBufferMapping::Close() {
memory_ = nullptr;
mapping_.reset();
}
} // namespace mojo::core::ipcz_driver
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