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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.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40284755): Remove this and spanify to fix the errors.
#pragma allow_unsafe_buffers
#endif
#include "base/memory/platform_shared_memory_mapper.h"
#include <sys/mman.h>
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
namespace base {
std::optional<span<uint8_t>> PlatformSharedMemoryMapper::Map(
subtle::PlatformSharedMemoryHandle handle,
bool write_allowed,
uint64_t offset,
size_t size) {
// IMPORTANT: Even if the mapping is readonly and the mapped data is not
// changing, the region must ALWAYS be mapped with MAP_SHARED, otherwise with
// ashmem the mapping is equivalent to a private anonymous mapping.
void* address =
mmap(nullptr, size, PROT_READ | (write_allowed ? PROT_WRITE : 0),
MAP_SHARED, handle, checked_cast<off_t>(offset));
if (address == MAP_FAILED) {
DPLOG(ERROR) << "mmap " << handle << " failed";
return std::nullopt;
}
return span(static_cast<uint8_t*>(address), size);
}
void PlatformSharedMemoryMapper::Unmap(span<uint8_t> mapping) {
if (munmap(mapping.data(), mapping.size()) < 0) {
DPLOG(ERROR) << "munmap";
}
}
} // namespace base
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