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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 "base/memory/platform_shared_memory_mapper.h"
#include <mach/vm_map.h>
#include "base/apple/mach_logging.h"
#include "base/containers/span.h"
#include "base/logging.h"
namespace base {
std::optional<span<uint8_t>> PlatformSharedMemoryMapper::Map(
subtle::PlatformSharedMemoryHandle handle,
bool write_allowed,
uint64_t offset,
size_t size) {
vm_prot_t vm_prot_write = write_allowed ? VM_PROT_WRITE : 0;
vm_address_t address = 0;
kern_return_t kr = vm_map(mach_task_self(),
&address, // Output parameter
size,
0, // Alignment mask
VM_FLAGS_ANYWHERE, handle, offset,
FALSE, // Copy
VM_PROT_READ | vm_prot_write, // Current protection
VM_PROT_READ | vm_prot_write, // Maximum protection
VM_INHERIT_NONE);
if (kr != KERN_SUCCESS) {
MACH_DLOG(ERROR, kr) << "vm_map";
return std::nullopt;
}
// SAFETY: vm_map() maps a memory segment of `size` bytes. Since
// `VM_FLAGS_ANYWHERE` is used, the address will be chosen by vm_map() and
// returned in `address`.
return UNSAFE_BUFFERS(base::span(reinterpret_cast<uint8_t*>(address), size));
}
void PlatformSharedMemoryMapper::Unmap(span<uint8_t> mapping) {
kern_return_t kr = vm_deallocate(
mach_task_self(), reinterpret_cast<vm_address_t>(mapping.data()),
mapping.size());
MACH_DLOG_IF(ERROR, kr != KERN_SUCCESS, kr) << "vm_deallocate";
}
} // namespace base
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