components/printing/service/public/cpp/pdf_service_mojo_utils.cc

// Copyright 2017 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 "components/printing/service/public/cpp/pdf_service_mojo_utils.h"

#include "base/memory/ref_counted_memory.h"
#include "base/memory/shared_memory.h"
#include "mojo/public/cpp/system/platform_handle.h"

namespace printing {

std::unique_ptr<base::SharedMemory> GetShmFromMojoHandle(
    mojo::ScopedSharedBufferHandle handle) {
  base::SharedMemoryHandle memory_handle;
  size_t memory_size = 0;
  bool read_only_flag = false;

  const MojoResult result = mojo::UnwrapSharedMemoryHandle(
      std::move(handle), &memory_handle, &memory_size, &read_only_flag);
  if (result != MOJO_RESULT_OK)
    return nullptr;
  DCHECK_GT(memory_size, 0u);

  std::unique_ptr<base::SharedMemory> shm =
      std::make_unique<base::SharedMemory>(memory_handle, read_only_flag);
  if (!shm->Map(memory_size)) {
    DLOG(ERROR) << "Map shared memory failed.";
    return nullptr;
  }
  return shm;
}

scoped_refptr<base::RefCountedBytes> GetDataFromMojoHandle(
    mojo::ScopedSharedBufferHandle handle) {
  std::unique_ptr<base::SharedMemory> shm =
      GetShmFromMojoHandle(std::move(handle));
  if (!shm)
    return nullptr;

  return base::MakeRefCounted<base::RefCountedBytes>(
      reinterpret_cast<const unsigned char*>(shm->memory()),
      shm->mapped_size());
}

}  // namespace printing