The Tor Browser: widget/windows/nsAppShell.cpp@ac0c01689b40 (annotated)

widget/windows/nsAppShell.cpp@ac0c01689b40 (annotated)

widget/windows/nsAppShell.cpp

Thu, 15 Jan 2015 15:59:08 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:59:08 +0100
branch: TOR_BUG_9701
changeset 10: ac0c01689b40
permissions: -rw-r--r--

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- 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"
 using namespace mozilla;
 using namespace mozilla::widget;
 // 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 : public nsIDOMMozWakeLockListener {
 public:
   NS_DECL_ISUPPORTS;
 private:
   NS_IMETHOD Callback(const nsAString& aTopic, const nsAString& aState) {
     bool isLocked = mLockedTopics.Contains(aTopic);
     bool shouldLock = aState.Equals(NS_LITERAL_STRING("locked-foreground"));
     if (isLocked == shouldLock) {
       return NS_OK;
     }
     if (shouldLock) {
       if (!mLockedTopics.Count()) {
         // This is the first topic to request the screen saver be disabled.
         // Prevent screen saver.
         SetThreadExecutionState(ES_DISPLAY_REQUIRED|ES_CONTINUOUS);
       }
       mLockedTopics.PutEntry(aTopic);
     } else {
       mLockedTopics.RemoveEntry(aTopic);
       if (!mLockedTopics.Count()) {
         // No other outstanding topics have requested screen saver be disabled.
         // Re-enable screen saver.
         SetThreadExecutionState(ES_CONTINUOUS);
       }
    }
     return NS_OK;
   }
   // Keep track of all the topics that have requested a wake lock. When the
   // number of topics in the hashtable reaches zero, we can uninhibit the
   // screensaver again.
   nsTHashtable<nsStringHashKey> mLockedTopics;
 };
 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;
   }
 }
 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;
 //-------------------------------------------------------------------------
 /*static*/ LRESULT CALLBACK
 nsAppShell::EventWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
   if (uMsg == sAppShellGeckoMsgId) {
     nsAppShell *as = reinterpret_cast<nsAppShell *>(lParam);
     as->NativeEventCallback();
     NS_RELEASE(as);
     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);
   }
 }
 nsresult
 nsAppShell::Init()
 {
 #ifdef MOZ_CRASHREPORTER
   LSPAnnotate();
 #endif
   mLastNativeEventScheduled = TimeStamp::NowLoRes();
   mozilla::ipc::windows::InitUIThread();
   sTaskbarButtonCreatedMsg = ::RegisterWindowMessageW(kTaskbarButtonEventId);
   NS_ASSERTION(sTaskbarButtonCreatedMsg, "Could not register taskbar button creation message");
   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, 10, 10, nullptr, nullptr, module, nullptr);
   NS_ENSURE_STATE(mEventWnd);
   return nsBaseAppShell::Init();
 }
 NS_IMETHODIMP
 nsAppShell::Run(void)
 {
   // Ignore failure; failing to start the application is not exactly an
   // appropriate response to failing to start an audio session.
   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();
   mozilla::widget::StopAudioSession();
   return rv;
 }
 NS_IMETHODIMP
 nsAppShell::Exit(void)
 {
   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(nullptr);
     mNativeCallbackPending = false;
   } else {
     mNativeCallbackPending = true;
   }
 }
 void
 nsAppShell::ScheduleNativeEventCallback()
 {
   // Post a message to the hidden message window
   NS_ADDREF_THIS(); // will be released when the event is processed
   {
     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.
         }
         ::TranslateMessage(&msg);
         ::DispatchMessageW(&msg);
       }
     } else if (mayWait) {
       // Block and wait for any posted application message
       mozilla::HangMonitor::Suspend();
       {
         GeckoProfilerSleepRAII profiler_sleep;
         ::WaitMessage();
       }
     }
   } 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;
 }

The Tor Browser / annotate

widget/windows/nsAppShell.cpp@ac0c01689b40 (annotated)

widget/windows/nsAppShell.cpp