libbrillo/brillo/daemons/daemon.cc

// Copyright 2014 The Chromium OS 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 <brillo/daemons/daemon.h>

#include <sysexits.h>

#include <base/bind.h>
#include <base/files/file_path.h>
#include <base/files/file_util.h>
#include <base/logging.h>
#include <base/run_loop.h>

namespace brillo {

Daemon::Daemon() : exit_code_{EX_OK} {
  message_loop_.SetAsCurrent();
}

Daemon::~Daemon() {
}

int Daemon::Run() {
  int exit_code = OnInit();
  if (exit_code != EX_OK)
    return exit_code;

  message_loop_.Run();

  OnShutdown(&exit_code_);

  // base::RunLoop::QuitClosure() causes the message loop to quit
  // immediately, even if pending tasks are still queued.
  // Run a secondary loop to make sure all those are processed.
  // This becomes important when working with D-Bus since dbus::Bus does
  // a bunch of clean-up tasks asynchronously when shutting down.
  while (message_loop_.RunOnce(false /* may_block */)) {}

  return exit_code_;
}

void Daemon::Quit() { QuitWithExitCode(EX_OK); }

void Daemon::QuitWithExitCode(int exit_code) {
  exit_code_ = exit_code;
  message_loop_.PostTask(FROM_HERE, QuitClosure());
}

void Daemon::RegisterHandler(
    int signal,
    const AsynchronousSignalHandlerInterface::SignalHandler& callback) {
  async_signal_handler_.RegisterHandler(signal, callback);
}

void Daemon::UnregisterHandler(int signal) {
  async_signal_handler_.UnregisterHandler(signal);
}

int Daemon::OnInit() {
  async_signal_handler_.Init();
  for (int signal : {SIGTERM, SIGINT}) {
    async_signal_handler_.RegisterHandler(
        signal, base::Bind(&Daemon::Shutdown, base::Unretained(this)));
  }
  async_signal_handler_.RegisterHandler(
      SIGHUP, base::Bind(&Daemon::Restart, base::Unretained(this)));
  return EX_OK;
}

void Daemon::OnShutdown(int* /* exit_code */) {
  // Do nothing.
}

bool Daemon::OnRestart() {
  // Not handled.
  return false;  // Returning false will shut down the daemon instead.
}

bool Daemon::Shutdown(const signalfd_siginfo& /* info */) {
  Quit();
  return true;  // Unregister the signal handler.
}

bool Daemon::Restart(const signalfd_siginfo& /* info */) {
  if (OnRestart())
    return false;  // Keep listening to the signal.
  Quit();
  return true;  // Unregister the signal handler.
}

}  // namespace brillo