base/memory/platform_shared_memory_mapper_mac.cc

// Copyright 2022 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/platform_shared_memory_mapper.h"

#include "base/logging.h"

#include <mach/mach_vm.h>
#include "base/mac/mach_logging.h"

namespace base {

absl::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;
  mach_vm_address_t address = 0;
  kern_return_t kr =
      mach_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) << "mach_vm_map";
    return absl::nullopt;
  }

  return make_span(reinterpret_cast<uint8_t*>(address), size);
}

void PlatformSharedMemoryMapper::Unmap(span<uint8_t> mapping) {
  kern_return_t kr = mach_vm_deallocate(
      mach_task_self(), reinterpret_cast<mach_vm_address_t>(mapping.data()),
      mapping.size());
  MACH_DLOG_IF(ERROR, kr != KERN_SUCCESS, kr) << "mach_vm_deallocate";
}

}  // namespace base