nsAppShell.cpp

/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "mozilla/ipc/MessageChannel.h"
#include "mozilla/ipc/WindowsMessageLoop.h"
#include "nsAppShell.h"
#include "nsToolkit.h"
#include "nsThreadUtils.h"
#include "WinUtils.h"
#include "WinTaskbar.h"
#include "WinMouseScrollHandler.h"
#include "nsWindowDefs.h"
#include "nsString.h"
#include "WinIMEHandler.h"
#include "mozilla/widget/AudioSession.h"
#include "mozilla/HangMonitor.h"
#include "nsIDOMWakeLockListener.h"
#include "nsIPowerManagerService.h"
#include "mozilla/StaticPtr.h"
#include "nsTHashtable.h"
#include "nsHashKeys.h"
#include "GeckoProfiler.h"
#include "nsComponentManagerUtils.h"
#include "ScreenHelperWin.h"
#include "HeadlessScreenHelper.h"
#include "mozilla/widget/ScreenManager.h"
#include "mozilla/Atomics.h"

#if defined(ACCESSIBILITY)
#include "mozilla/a11y/Compatibility.h"
#include "mozilla/a11y/Platform.h"
#endif // defined(ACCESSIBILITY)

// These are two messages that the code in winspool.drv on Windows 7 explicitly
// waits for while it is pumping other Windows messages, during display of the
// Printer Properties dialog.
#define MOZ_WM_PRINTER_PROPERTIES_COMPLETION 0x5b7a
#define MOZ_WM_PRINTER_PROPERTIES_FAILURE 0x5b7f

using namespace mozilla;
using namespace mozilla::widget;

#define WAKE_LOCK_LOG(...) MOZ_LOG(gWinWakeLockLog, mozilla::LogLevel::Debug, (__VA_ARGS__))
static mozilla::LazyLogModule gWinWakeLockLog("WinWakeLock");

// A wake lock listener that disables screen saver when requested by
// Gecko. For example when we're playing video in a foreground tab we
// don't want the screen saver to turn on.
class WinWakeLockListener final : public nsIDOMMozWakeLockListener
{
public:
  NS_DECL_ISUPPORTS

private:
  ~WinWakeLockListener() {}

  NS_IMETHOD Callback(const nsAString& aTopic, const nsAString& aState) override {
    if (!aTopic.EqualsASCII("screen") &&
        !aTopic.EqualsASCII("audio-playing") &&
        !aTopic.EqualsASCII("video-playing")) {
      return NS_OK;
    }

    // we should still hold the lock for background audio.
    if (aTopic.EqualsASCII("audio-playing") &&
        aState.EqualsASCII("locked-background")) {
      return NS_OK;
    }

    if (aTopic.EqualsASCII("screen") ||
        aTopic.EqualsASCII("video-playing")) {
      mRequireForDisplay = aState.EqualsASCII("locked-foreground");
    }

    // Note the wake lock code ensures that we're not sent duplicate
    // "locked-foreground" notifications when multiple wake locks are held.
    if (aState.EqualsASCII("locked-foreground")) {
      WAKE_LOCK_LOG("WinWakeLock: Blocking screen saver");
      if (mRequireForDisplay) {
        // Prevent the display turning off and block the screen saver.
        SetThreadExecutionState(ES_DISPLAY_REQUIRED|ES_CONTINUOUS);
      } else {
        SetThreadExecutionState(ES_SYSTEM_REQUIRED|ES_CONTINUOUS);
      }
    } else {
      WAKE_LOCK_LOG("WinWakeLock: Unblocking screen saver");
      // Unblock display/screen saver turning off.
      SetThreadExecutionState(ES_CONTINUOUS);
    }
    return NS_OK;
  }

  bool mRequireForDisplay = false;
};

NS_IMPL_ISUPPORTS(WinWakeLockListener, nsIDOMMozWakeLockListener)
StaticRefPtr<WinWakeLockListener> sWakeLockListener;

static void
AddScreenWakeLockListener()
{
  nsCOMPtr<nsIPowerManagerService> sPowerManagerService = do_GetService(POWERMANAGERSERVICE_CONTRACTID);
  if (sPowerManagerService) {
    sWakeLockListener = new WinWakeLockListener();
    sPowerManagerService->AddWakeLockListener(sWakeLockListener);
  } else {
    NS_WARNING("Failed to retrieve PowerManagerService, wakelocks will be broken!");
  }
}

static void
RemoveScreenWakeLockListener()
{
  nsCOMPtr<nsIPowerManagerService> sPowerManagerService = do_GetService(POWERMANAGERSERVICE_CONTRACTID);
  if (sPowerManagerService) {
    sPowerManagerService->RemoveWakeLockListener(sWakeLockListener);
    sPowerManagerService = nullptr;
    sWakeLockListener = nullptr;
  }
}

class SingleNativeEventPump final : public nsIThreadObserver
{
public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSITHREADOBSERVER

  SingleNativeEventPump()
  {
    MOZ_ASSERT(!XRE_UseNativeEventProcessing(),
               "Should only be used when not properly processing events.");
  }

private:
  ~SingleNativeEventPump() {}
};

NS_IMPL_ISUPPORTS(SingleNativeEventPump, nsIThreadObserver)

NS_IMETHODIMP
SingleNativeEventPump::OnDispatchedEvent() { return NS_OK; }

NS_IMETHODIMP
SingleNativeEventPump::OnProcessNextEvent(nsIThreadInternal* aThread,
                                          bool aMayWait)
{
  MSG msg;
  bool gotMessage = WinUtils::PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE);
  if (gotMessage) {
    ::TranslateMessage(&msg);
    ::DispatchMessageW(&msg);
  }
  return NS_OK;
}

NS_IMETHODIMP
SingleNativeEventPump::AfterProcessNextEvent(nsIThreadInternal* aThread,
                                             bool aMayWait)
{
  return NS_OK;
}

namespace mozilla {
namespace widget {
// Native event callback message.
UINT sAppShellGeckoMsgId = RegisterWindowMessageW(L"nsAppShell:EventID");
} }

const wchar_t* kTaskbarButtonEventId = L"TaskbarButtonCreated";
UINT sTaskbarButtonCreatedMsg;

/* static */
UINT nsAppShell::GetTaskbarButtonCreatedMessage() {
	return sTaskbarButtonCreatedMsg;
}

namespace mozilla {
namespace crashreporter {
void LSPAnnotate();
} // namespace crashreporter
} // namespace mozilla

using mozilla::crashreporter::LSPAnnotate;

//-------------------------------------------------------------------------

// Note that since we're on x86-ish processors here, ReleaseAcquire is the
// semantics that normal loads and stores would use anyway.
static Atomic<size_t, ReleaseAcquire> sOutstandingNativeEventCallbacks;

/*static*/ LRESULT CALLBACK
nsAppShell::EventWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
  if (uMsg == sAppShellGeckoMsgId) {
    // The app shell might have been destroyed between this message being
    // posted and being executed, so be extra careful.
    if (!sOutstandingNativeEventCallbacks) {
      return TRUE;
    }

    nsAppShell *as = reinterpret_cast<nsAppShell *>(lParam);
    as->NativeEventCallback();
    --sOutstandingNativeEventCallbacks;
    return TRUE;
  }
  return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

nsAppShell::~nsAppShell()
{
  if (mEventWnd) {
    // DestroyWindow doesn't do anything when called from a non UI thread.
    // Since mEventWnd was created on the UI thread, it must be destroyed on
    // the UI thread.
    SendMessage(mEventWnd, WM_CLOSE, 0, 0);
  }

  // Cancel any outstanding native event callbacks.
  sOutstandingNativeEventCallbacks = 0;
}

#if defined(ACCESSIBILITY)

static ULONG gUiaMsg;
static HHOOK gUiaHook;
static uint32_t gUiaAttempts;
static const uint32_t kMaxUiaAttempts = 5;

static void InitUIADetection();

static LRESULT CALLBACK
UiaHookProc(int aCode, WPARAM aWParam, LPARAM aLParam)
{
  if (aCode < 0) {
    return ::CallNextHookEx(nullptr, aCode, aWParam, aLParam);
  }

  auto cwp = reinterpret_cast<CWPSTRUCT*>(aLParam);
  if (gUiaMsg && cwp->message == gUiaMsg) {
    if (gUiaAttempts < kMaxUiaAttempts) {
      ++gUiaAttempts;

      Maybe<bool> shouldCallNextHook =
        a11y::Compatibility::OnUIAMessage(cwp->wParam, cwp->lParam);
      if (shouldCallNextHook.isSome()) {
        // We've got an instantiator.
        if (!shouldCallNextHook.value()) {
          // We're blocking this instantiation. We need to keep this hook set
          // so that we can catch any future instantiation attempts.
          return 0;
        }

        // We're allowing the instantiator to proceed, so this hook is no longer
        // needed.
        if (::UnhookWindowsHookEx(gUiaHook)) {
          gUiaHook = nullptr;
        }
      } else {
        // Our hook might be firing after UIA; let's try reinstalling ourselves.
        InitUIADetection();
      }
    } else {
      // We've maxed out our attempts. Let's unhook.
      if (::UnhookWindowsHookEx(gUiaHook)) {
        gUiaHook = nullptr;
      }
    }
  }

  return ::CallNextHookEx(nullptr, aCode, aWParam, aLParam);
}

static void
InitUIADetection()
{
  if (gUiaHook) {
    // In this case we want to re-hook so that the hook is always called ahead
    // of UIA's hook.
    if (::UnhookWindowsHookEx(gUiaHook)) {
      gUiaHook = nullptr;
    }
  }

  if (!gUiaMsg) {
    // This is the message that UIA sends to trigger a command. UIA's
    // CallWndProc looks for this message and then handles the request.
    // Our hook gets in front of UIA's hook and examines the message first.
    gUiaMsg = ::RegisterWindowMessageW(L"HOOKUTIL_MSG");
  }

  if (!gUiaHook) {
    gUiaHook = ::SetWindowsHookEx(WH_CALLWNDPROC, &UiaHookProc, nullptr,
                                  ::GetCurrentThreadId());
  }
}

NS_IMETHODIMP
nsAppShell::Observe(nsISupports* aSubject, const char* aTopic,
                    const char16_t* aData)
{
  if (XRE_IsParentProcess() && !strcmp(aTopic, "dll-loaded-main-thread")) {
    if (a11y::PlatformDisabledState() != a11y::ePlatformIsDisabled && !gUiaHook) {
      nsDependentString dllName(aData);

      if (StringEndsWith(dllName, NS_LITERAL_STRING("uiautomationcore.dll"),
                         nsCaseInsensitiveStringComparator())) {
        InitUIADetection();

        // Now that we've handled the observer notification, we can remove it
        nsCOMPtr<nsIObserverService> obsServ(mozilla::services::GetObserverService());
        obsServ->RemoveObserver(this, "dll-loaded-main-thread");
      }
    }

    return NS_OK;
  }

  return nsBaseAppShell::Observe(aSubject, aTopic, aData);
}

#endif // defined(ACCESSIBILITY)

nsresult
nsAppShell::Init()
{
  LSPAnnotate();

  mozilla::ipc::windows::InitUIThread();

  sTaskbarButtonCreatedMsg = ::RegisterWindowMessageW(kTaskbarButtonEventId);
  NS_ASSERTION(sTaskbarButtonCreatedMsg, "Could not register taskbar button creation message");

  // The hidden message window is used for interrupting the processing of native
  // events, so that we can process gecko events. Therefore, we only need it if
  // we are processing native events.
  if (XRE_UseNativeEventProcessing()) {
    mLastNativeEventScheduled = TimeStamp::NowLoRes();

    WNDCLASSW wc;
    HINSTANCE module = GetModuleHandle(nullptr);

    const wchar_t *const kWindowClass = L"nsAppShell:EventWindowClass";
    if (!GetClassInfoW(module, kWindowClass, &wc)) {
      wc.style         = 0;
      wc.lpfnWndProc   = EventWindowProc;
      wc.cbClsExtra    = 0;
      wc.cbWndExtra    = 0;
      wc.hInstance     = module;
      wc.hIcon         = nullptr;
      wc.hCursor       = nullptr;
      wc.hbrBackground = (HBRUSH) nullptr;
      wc.lpszMenuName  = (LPCWSTR) nullptr;
      wc.lpszClassName = kWindowClass;
      RegisterClassW(&wc);
    }

    mEventWnd = CreateWindowW(kWindowClass, L"nsAppShell:EventWindow",
                              0, 0, 0, 10, 10, HWND_MESSAGE, nullptr, module,
                              nullptr);
    NS_ENSURE_STATE(mEventWnd);
  } else {
    // We're not generally processing native events, but still using GDI and we
    // still have some internal windows, e.g. from calling CoInitializeEx.
    // So we use a class that will do a single event pump where previously we
    // might have processed multiple events to make sure any occasional messages
    // to these windows are processed. This also allows any internal Windows
    // messages to be processed to ensure the GDI data remains fresh.
    nsCOMPtr<nsIThreadInternal> threadInt =
      do_QueryInterface(NS_GetCurrentThread());
    if (threadInt) {
      threadInt->SetObserver(new SingleNativeEventPump());
    }
  }

  if (XRE_IsParentProcess()) {
    ScreenManager& screenManager = ScreenManager::GetSingleton();
    if (gfxPlatform::IsHeadless()) {
      screenManager.SetHelper(mozilla::MakeUnique<HeadlessScreenHelper>());
    } else {
      screenManager.SetHelper(mozilla::MakeUnique<ScreenHelperWin>());
      ScreenHelperWin::RefreshScreens();
    }

#if defined(ACCESSIBILITY)
    if (::GetModuleHandleW(L"uiautomationcore.dll")) {
      InitUIADetection();
    } else {
      nsCOMPtr<nsIObserverService> obsServ(mozilla::services::GetObserverService());
      obsServ->AddObserver(this, "dll-loaded-main-thread", false);
    }
#endif // defined(ACCESSIBILITY)
  }

  return nsBaseAppShell::Init();
}

NS_IMETHODIMP
nsAppShell::Run(void)
{
  // Content processes initialize audio later through PContent using audio
  // tray id information pulled from the browser process AudioSession. This
  // way the two share a single volume control.
  // Note StopAudioSession() is called from nsAppRunner.cpp after xpcom is torn
  // down to insure the browser shuts down after child processes.
  if (XRE_IsParentProcess()) {
    mozilla::widget::StartAudioSession();
  }

  // Add an observer that disables the screen saver when requested by Gecko.
  // For example when we're playing video in the foreground tab.
  AddScreenWakeLockListener();

  nsresult rv = nsBaseAppShell::Run();

  RemoveScreenWakeLockListener();

  return rv;
}

NS_IMETHODIMP
nsAppShell::Exit(void)
{
#if defined(ACCESSIBILITY)
  if (XRE_IsParentProcess()) {
    nsCOMPtr<nsIObserverService> obsServ(mozilla::services::GetObserverService());
    obsServ->RemoveObserver(this, "dll-loaded-main-thread");

    if (gUiaHook && ::UnhookWindowsHookEx(gUiaHook)) {
      gUiaHook = nullptr;
    }
  }
#endif // defined(ACCESSIBILITY)

  return nsBaseAppShell::Exit();
}

void
nsAppShell::DoProcessMoreGeckoEvents()
{
  // Called by nsBaseAppShell's NativeEventCallback() after it has finished
  // processing pending gecko events and there are still gecko events pending
  // for the thread. (This can happen if NS_ProcessPendingEvents reached it's
  // starvation timeout limit.) The default behavior in nsBaseAppShell is to
  // call ScheduleNativeEventCallback to post a follow up native event callback
  // message. This triggers an additional call to NativeEventCallback for more
  // gecko event processing.

  // There's a deadlock risk here with certain internal Windows modal loops. In
  // our dispatch code, we prioritize messages so that input is handled first.
  // However Windows modal dispatch loops often prioritize posted messages. If
  // we find ourselves in a tight gecko timer loop where NS_ProcessPendingEvents
  // takes longer than the timer duration, NS_HasPendingEvents(thread) will
  // always be true. ScheduleNativeEventCallback will be called on every
  // NativeEventCallback callback, and in a Windows modal dispatch loop, the
  // callback message will be processed first -> input gets starved, dead lock.

  // To avoid, don't post native callback messages from NativeEventCallback
  // when we're in a modal loop. This gets us back into the Windows modal
  // dispatch loop dispatching input messages. Once we drop out of the modal
  // loop, we use mNativeCallbackPending to fire off a final NativeEventCallback
  // if we need it, which insures NS_ProcessPendingEvents gets called and all
  // gecko events get processed.
  if (mEventloopNestingLevel < 2) {
    OnDispatchedEvent();
    mNativeCallbackPending = false;
  } else {
    mNativeCallbackPending = true;
  }
}

void
nsAppShell::ScheduleNativeEventCallback()
{
  MOZ_ASSERT(mEventWnd,
             "We should have created mEventWnd in Init, if this is called.");

  // Post a message to the hidden message window
  ++sOutstandingNativeEventCallbacks;
  {
    MutexAutoLock lock(mLastNativeEventScheduledMutex);
    // Time stamp this event so we can detect cases where the event gets
    // dropping in sub classes / modal loops we do not control.
    mLastNativeEventScheduled = TimeStamp::NowLoRes();
  }
  ::PostMessage(mEventWnd, sAppShellGeckoMsgId, 0, reinterpret_cast<LPARAM>(this));
}

bool
nsAppShell::ProcessNextNativeEvent(bool mayWait)
{
  // Notify ipc we are spinning a (possibly nested) gecko event loop.
  mozilla::ipc::MessageChannel::NotifyGeckoEventDispatch();

  bool gotMessage = false;

  do {
    MSG msg;
    bool uiMessage = false;

    // For avoiding deadlock between our process and plugin process by
    // mouse wheel messages, we're handling actually when we receive one of
    // following internal messages which is posted by native mouse wheel
    // message handler. Any other events, especially native modifier key
    // events, should not be handled between native message and posted
    // internal message because it may make different modifier key state or
    // mouse cursor position between them.
    if (mozilla::widget::MouseScrollHandler::IsWaitingInternalMessage()) {
      gotMessage = WinUtils::PeekMessage(&msg, nullptr, MOZ_WM_MOUSEWHEEL_FIRST,
                                         MOZ_WM_MOUSEWHEEL_LAST, PM_REMOVE);
      NS_ASSERTION(gotMessage,
                   "waiting internal wheel message, but it has not come");
      uiMessage = gotMessage;
    }

    if (!gotMessage) {
      gotMessage = WinUtils::PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE);
      uiMessage =
        (msg.message >= WM_KEYFIRST && msg.message <= WM_IME_KEYLAST) ||
        (msg.message >= NS_WM_IMEFIRST && msg.message <= NS_WM_IMELAST) ||
        (msg.message >= WM_MOUSEFIRST && msg.message <= WM_MOUSELAST);
    }

    if (gotMessage) {
      if (msg.message == WM_QUIT) {
        ::PostQuitMessage(msg.wParam);
        Exit();
      } else {
        // If we had UI activity we would be processing it now so we know we
        // have either kUIActivity or kActivityNoUIAVail.
        mozilla::HangMonitor::NotifyActivity(
          uiMessage ? mozilla::HangMonitor::kUIActivity :
                      mozilla::HangMonitor::kActivityNoUIAVail);

        if (msg.message >= WM_KEYFIRST && msg.message <= WM_KEYLAST &&
            IMEHandler::ProcessRawKeyMessage(msg)) {
          continue;  // the message is consumed.
        }

        // Store Printer Properties messages for reposting, because they are not
        // processed by a window procedure, but are explicitly waited for in the
        // winspool.drv code that will be further up the stack.
        if (msg.message == MOZ_WM_PRINTER_PROPERTIES_COMPLETION ||
            msg.message == MOZ_WM_PRINTER_PROPERTIES_FAILURE) {
          mMsgsToRepost.push_back(msg);
          continue;
        }

        ::TranslateMessage(&msg);
        ::DispatchMessageW(&msg);
      }
    } else if (mayWait) {
      // Block and wait for any posted application message
      mozilla::HangMonitor::Suspend();
      {
        AUTO_PROFILER_LABEL("nsAppShell::ProcessNextNativeEvent::Wait", IDLE);
        AUTO_PROFILER_THREAD_SLEEP;
        WinUtils::WaitForMessage();
      }
    }
  } while (!gotMessage && mayWait);

  // See DoProcessNextNativeEvent, mEventloopNestingLevel will be
  // one when a modal loop unwinds.
  if (mNativeCallbackPending && mEventloopNestingLevel == 1)
    DoProcessMoreGeckoEvents();

  // Check for starved native callbacks. If we haven't processed one
  // of these events in NATIVE_EVENT_STARVATION_LIMIT, fire one off.
  static const mozilla::TimeDuration nativeEventStarvationLimit =
    mozilla::TimeDuration::FromSeconds(NATIVE_EVENT_STARVATION_LIMIT);

  TimeDuration timeSinceLastNativeEventScheduled;
  {
    MutexAutoLock lock(mLastNativeEventScheduledMutex);
    timeSinceLastNativeEventScheduled =
        TimeStamp::NowLoRes() - mLastNativeEventScheduled;
  }
  if (timeSinceLastNativeEventScheduled > nativeEventStarvationLimit) {
    ScheduleNativeEventCallback();
  }

  return gotMessage;
}

nsresult
nsAppShell::AfterProcessNextEvent(nsIThreadInternal* /* unused */,
                                  bool /* unused */)
{
  if (!mMsgsToRepost.empty()) {
    for (MSG msg : mMsgsToRepost) {
      ::PostMessageW(msg.hwnd, msg.message, msg.wParam, msg.lParam);
    }
    mMsgsToRepost.clear();
  }
  return NS_OK;
}