// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/chrome_browser_main_posix.h"

#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stddef.h>
#include <string.h>
#include <sys/resource.h>

#include <string>

#include "base/check_op.h"
#include "base/compiler_specific.h"
#include "base/functional/bind.h"
#include "base/notreached.h"
#include "build/build_config.h"
#include "chrome/browser/devtools/chrome_devtools_manager_delegate.h"
#include "chrome/browser/lifetime/application_lifetime.h"
#include "chrome/browser/lifetime/application_lifetime_desktop.h"
#include "chrome/browser/sessions/session_restore.h"
#include "chrome/browser/shutdown_signal_handlers_posix.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/common/result_codes.h"

using content::BrowserThread;

namespace {

// See comment in |PreEarlyInitialization()|, where sigaction is called.
void SIGCHLDHandler(int signal) {
}

// ExitHandler takes care of servicing an exit (from a signal) at the
// appropriate time. Specifically if we get an exit and have not finished
// session restore we delay the exit. To do otherwise means we're exiting part
// way through startup which causes all sorts of problems.
class ExitHandler {
 public:
  ExitHandler(const ExitHandler&) = delete;
  ExitHandler& operator=(const ExitHandler&) = delete;

  // Invokes exit when appropriate.
  static void ExitWhenPossibleOnUIThread(int signal);

 private:
  ExitHandler();
  ~ExitHandler();

  // Called when a session restore has finished.
  void OnSessionRestoreDone(Profile* profile, int num_tabs_restored);

  // Does the appropriate call to Exit.
  static void Exit();

  // Points to the on-session-restored callback that was registered with
  // SessionRestore's callback list. When objects of this class are destroyed,
  // the subscription's destructor will automatically unregister the callback in
  // SessionRestore, so that the callback list does not contain any obsolete
  // callbacks.
  base::CallbackListSubscription on_session_restored_callback_subscription_;
};

// static
void ExitHandler::ExitWhenPossibleOnUIThread(int signal) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

  // DevTools delegate's browser keeplive may prevent browser from closing so
  // remove it before proceeding because we have an explicit shutdown request.
  ChromeDevToolsManagerDelegate::AllowBrowserToClose();

  if (SessionRestore::IsRestoringSynchronously()) {
    // ExitHandler takes care of deleting itself.
    new ExitHandler();
  } else {
#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_MAC)
    switch (signal) {
      case SIGINT:
      case SIGHUP:
        // SIGINT gets sent when the user types Ctrl+C, but the session is
        // likely not going away, so try to exit gracefully.  SIGHUP is sent on
        // most systems as a first warning of shutdown.  If the process takes
        // too long to quit, the next signal is usually SIGTERM.
        Exit();
        break;
      case SIGTERM:
        // SIGTERM is usually sent instead of SIGKILL to gracefully shutdown
        // processes.  But most systems use it as a shutdown warning, so
        // conservatively assume that the session is ending. On macOS, launchd
        // delivers SIGTERM at logout, shutdown, reboot, or update. If the
        // process still doesn't quit within a bounded time, most systems will
        // finally send SIGKILL, which we're unable to install a signal handler
        // for.
        // TODO(thomasanderson): Try to distinguish if the session is really
        // ending or not.  Maybe there's a systemd or DBus API to query.
        chrome::SessionEnding();
        break;
      default:
        NOTREACHED();
    }
#else
    Exit();
#endif
  }
}

ExitHandler::ExitHandler() {
  on_session_restored_callback_subscription_ =
      SessionRestore::RegisterOnSessionRestoredCallback(base::BindRepeating(
          &ExitHandler::OnSessionRestoreDone, base::Unretained(this)));
}

ExitHandler::~ExitHandler() = default;

void ExitHandler::OnSessionRestoreDone(Profile* profile, int /* num_tabs */) {
  if (!SessionRestore::IsRestoringSynchronously()) {
    // At this point the message loop may not be running (meaning we haven't
    // gotten through browser startup, but are close). Post the task to at which
    // point the message loop is running.
    content::GetUIThreadTaskRunner({})->PostTask(
        FROM_HERE, base::BindOnce(&ExitHandler::Exit));
    delete this;
  }
}

// static
void ExitHandler::Exit() {
#if BUILDFLAG(IS_CHROMEOS)
  // On ChromeOS, exiting on signal should be always clean.
  chrome::ExitIgnoreUnloadHandlers();
#else
  chrome::AttemptExit();
#endif
}

}  // namespace

// ChromeBrowserMainPartsPosix -------------------------------------------------

ChromeBrowserMainPartsPosix::ChromeBrowserMainPartsPosix(
    bool is_integration_test,
    StartupData* startup_data)
    : ChromeBrowserMainParts(is_integration_test, startup_data) {}

int ChromeBrowserMainPartsPosix::PreEarlyInitialization() {
  const int result = ChromeBrowserMainParts::PreEarlyInitialization();
  if (result != content::RESULT_CODE_NORMAL_EXIT)
    return result;

  // We need to accept SIGCHLD, even though our handler is a no-op because
  // otherwise we cannot wait on children. (According to POSIX 2001.)
  struct sigaction action = {};
  action.sa_handler = SIGCHLDHandler;
  CHECK_EQ(0, sigaction(SIGCHLD, &action, nullptr));

  return content::RESULT_CODE_NORMAL_EXIT;
}

void ChromeBrowserMainPartsPosix::PostCreateMainMessageLoop() {
  ChromeBrowserMainParts::PostCreateMainMessageLoop();

  // Exit in response to SIGINT, SIGTERM, etc.
  InstallShutdownSignalHandlers(
      base::BindOnce(&ExitHandler::ExitWhenPossibleOnUIThread),
      content::GetUIThreadTaskRunner({}));
}

void ChromeBrowserMainPartsPosix::ShowMissingLocaleMessageBox() {
#if BUILDFLAG(IS_CHROMEOS)
  NOTREACHED();  // Should not ever happen on ChromeOS.
#elif BUILDFLAG(IS_MAC)
  // Not called on Mac because we load the locale files differently.
  NOTREACHED();
#elif defined(USE_AURA)
  // TODO(port): We may want a views based message dialog here eventually, but
  // for now, crash.
  NOTREACHED();
#else
#error "Need MessageBox implementation."
#endif
}