shell/child_process_host.cc

// Copyright 2014 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 "shell/child_process_host.h"

#include "base/base_switches.h"
#include "base/bind.h"
#include "base/command_line.h"
#include "base/files/file_path.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/message_loop/message_loop.h"
#include "base/process/kill.h"
#include "base/process/launch.h"
#include "base/task_runner.h"
#include "base/task_runner_util.h"
#include "mojo/edk/embedder/embedder.h"
#include "mojo/public/cpp/system/message_pipe.h"
#include "shell/context.h"
#include "shell/switches.h"
#include "shell/task_runners.h"

namespace shell {

ChildProcessHost::ChildProcessHost(Context* context)
    : context_(context), channel_info_(nullptr) {
}

ChildProcessHost::~ChildProcessHost() {
  DCHECK(!child_process_.IsValid());
}

void ChildProcessHost::Start() {
  DCHECK(!child_process_.IsValid());

  mojo::ScopedMessagePipeHandle handle(mojo::embedder::CreateChannel(
      platform_channel_pair_.PassServerHandle(),
      context_->task_runners()->io_runner(),
      base::Bind(&ChildProcessHost::DidCreateChannel, base::Unretained(this)),
      base::MessageLoop::current()->message_loop_proxy()));

  controller_.Bind(mojo::InterfacePtrInfo<ChildController>(handle.Pass(), 0u));
  controller_.set_error_handler(this);

  CHECK(base::PostTaskAndReplyWithResult(
      context_->task_runners()->blocking_pool(), FROM_HERE,
      base::Bind(&ChildProcessHost::DoLaunch, base::Unretained(this)),
      base::Bind(&ChildProcessHost::DidStart, base::Unretained(this))));
}

int ChildProcessHost::Join() {
  DCHECK(child_process_.IsValid());
  int rv = -1;
  LOG_IF(ERROR, !child_process_.WaitForExit(&rv))
      << "Failed to wait for child process";
  child_process_.Close();
  return rv;
}

void ChildProcessHost::StartApp(
    const mojo::String& app_path,
    mojo::InterfaceRequest<mojo::Application> application_request,
    const ChildController::StartAppCallback& on_app_complete) {
  DCHECK(controller_);

  on_app_complete_ = on_app_complete;
  controller_->StartApp(
      app_path, application_request.Pass(),
      base::Bind(&ChildProcessHost::AppCompleted, base::Unretained(this)));
}

void ChildProcessHost::ExitNow(int32_t exit_code) {
  DCHECK(controller_);

  controller_->ExitNow(exit_code);
}

void ChildProcessHost::DidStart(bool success) {
  DVLOG(2) << "ChildProcessHost::DidStart()";

  if (!success) {
    LOG(ERROR) << "Failed to start app child process";
    AppCompleted(MOJO_RESULT_UNKNOWN);
    return;
  }
}

// Callback for |mojo::embedder::CreateChannel()|.
void ChildProcessHost::DidCreateChannel(
    mojo::embedder::ChannelInfo* channel_info) {
  DVLOG(2) << "ChildProcessHost::DidCreateChannel()";

  CHECK(channel_info);
  channel_info_ = channel_info;
}

bool ChildProcessHost::DoLaunch() {
  static const char* kForwardSwitches[] = {
      switches::kTraceToConsole, switches::kV, switches::kVModule,
  };

  base::CommandLine child_command_line(context_->mojo_shell_child_path());
  child_command_line.CopySwitchesFrom(*base::CommandLine::ForCurrentProcess(),
                                      kForwardSwitches,
                                      arraysize(kForwardSwitches));
  child_command_line.AppendSwitch(switches::kChildProcess);

  mojo::embedder::HandlePassingInformation handle_passing_info;
  platform_channel_pair_.PrepareToPassClientHandleToChildProcess(
      &child_command_line, &handle_passing_info);

  base::LaunchOptions options;
  options.fds_to_remap = &handle_passing_info;
  DVLOG(2) << "Launching child with command line: "
           << child_command_line.GetCommandLineString();
  child_process_ = base::LaunchProcess(child_command_line, options);
  if (!child_process_.IsValid())
    return false;

  platform_channel_pair_.ChildProcessLaunched();
  return true;
}

void ChildProcessHost::AppCompleted(int32_t result) {
  if (!on_app_complete_.is_null()) {
    auto on_app_complete = on_app_complete_;
    on_app_complete_.reset();
    on_app_complete.Run(result);
  }
}

void ChildProcessHost::OnConnectionError() {
  AppCompleted(MOJO_RESULT_UNKNOWN);
}

}  // namespace shell