Bug 684627 - Add time limit to nsEventStateManager::IsHandlingUserInput(). r=smaug

content/base/public/nsContentUtils.h

@@ -83,6 +83,7 @@ static fp_except_t oldmask = fpsetmask(~allmask);
 #include "nsHtml5Parser.h"
 #include "nsIFragmentContentSink.h"
 #include "nsMathUtils.h"
+#include "mozilla/TimeStamp.h"
 
 struct nsNativeKeyEvent; // Don't include nsINativeKeyBindings.h here: it will force strange compilation error!
 
@@ -189,6 +190,7 @@ class nsContentUtils
 {
   friend class nsAutoScriptBlockerSuppressNodeRemoved;
   typedef mozilla::dom::Element Element;
+  typedef mozilla::TimeDuration TimeDuration;
 
 public:
   static nsresult Init();
@@ -1720,6 +1722,13 @@ public:
    */
   static PRBool IsFullScreenKeyInputRestricted();
 
+  /**
+   * Returns the time limit on handling user input before
+   * nsEventStateManager::IsHandlingUserInput() stops returning PR_TRUE.
+   * This enables us to detect long running user-generated event handlers.
+   */
+  static TimeDuration HandlingUserInputTimeout();
+
   static void GetShiftText(nsAString& text);
   static void GetControlText(nsAString& text);
   static void GetMetaText(nsAString& text);
@@ -1887,6 +1896,7 @@ private:
   static PRBool sIsFullScreenApiEnabled;
   static PRBool sTrustedFullScreenOnly;
   static PRBool sFullScreenKeyInputRestricted;
+  static PRUint32 sHandlingInputTimeout;
 
   static nsHtml5Parser* sHTMLFragmentParser;
   static nsIParser* sXMLFragmentParser;

content/base/src/nsContentUtils.cpp

@@ -201,6 +201,7 @@ static NS_DEFINE_CID(kXTFServiceCID, NS_XTFSERVICE_CID);
 #endif
 #include "nsDOMTouchEvent.h"
 #include "nsIScriptElement.h"
+#include "prdtoa.h"
 
 #include "mozilla/Preferences.h"
 
@@ -266,6 +267,8 @@ PRBool nsContentUtils::sIsFullScreenApiEnabled = PR_FALSE;
 PRBool nsContentUtils::sTrustedFullScreenOnly = PR_TRUE;
 PRBool nsContentUtils::sFullScreenKeyInputRestricted = PR_TRUE;
 
+PRUint32 nsContentUtils::sHandlingInputTimeout = 1000;
+
 nsHtml5Parser* nsContentUtils::sHTMLFragmentParser = nsnull;
 nsIParser* nsContentUtils::sXMLFragmentParser = nsnull;
 nsIFragmentContentSink* nsContentUtils::sXMLFragmentSink = nsnull;
@@ -319,6 +322,13 @@ class nsSameOriginChecker : public nsIChannelEventSink,
   NS_DECL_NSIINTERFACEREQUESTOR
 };
 
+/* static */
+TimeDuration
+nsContentUtils::HandlingUserInputTimeout()
+{
+  return TimeDuration::FromMilliseconds(sHandlingInputTimeout);
+}
+
 // static
 nsresult
 nsContentUtils::Init()
@@ -397,6 +407,10 @@ nsContentUtils::Init()
   Preferences::AddBoolVarCache(&sFullScreenKeyInputRestricted,
                                "full-screen-api.key-input-restricted");
 
+  Preferences::AddUintVarCache(&sHandlingInputTimeout,
+                               "dom.event.handling-user-input-time-limit",
+                               1000);
+
   sInitialized = PR_TRUE;
 
   return NS_OK;

content/events/src/nsEventStateManager.cpp

@@ -175,6 +175,8 @@ static PRUint32 gPixelScrollDeltaTimeout = 0;
 static nscoord
 GetScrollableLineHeight(nsIFrame* aTargetFrame);
 
+TimeStamp nsEventStateManager::sHandlingInputStart;
+
 static inline PRBool
 IsMouseEventReal(nsEvent* aEvent)
 {

content/events/src/nsEventStateManager.h

@@ -57,6 +57,8 @@
 #include "nsFocusManager.h"
 #include "nsIDocument.h"
 #include "nsEventStates.h"
+#include "mozilla/TimeStamp.h"
+#include "nsContentUtils.h"
 
 class nsIPresShell;
 class nsIDocShell;
@@ -80,6 +82,10 @@ class nsEventStateManager : public nsSupportsWeakReference,
 {
   friend class nsMouseWheelTransaction;
 public:
+
+  typedef mozilla::TimeStamp TimeStamp;
+  typedef mozilla::TimeDuration TimeDuration;
+
   nsEventStateManager();
   virtual ~nsEventStateManager();
 
@@ -169,16 +175,27 @@ public:
   static void StartHandlingUserInput()
   {
     ++sUserInputEventDepth;
+    if (sUserInputEventDepth == 1) {
+      sHandlingInputStart = TimeStamp::Now();
+    }
   }
 
   static void StopHandlingUserInput()
   {
     --sUserInputEventDepth;
+    if (sUserInputEventDepth == 0) {
+      sHandlingInputStart = TimeStamp();
+    }
   }
 
   static PRBool IsHandlingUserInput()
   {
-    return sUserInputEventDepth > 0;
+    if (sUserInputEventDepth <= 0) {
+      return PR_FALSE;
+    }
+    TimeDuration timeout = nsContentUtils::HandlingUserInputTimeout();
+    return timeout <= TimeDuration(0) ||
+           (TimeStamp::Now() - sHandlingInputStart) <= timeout;
   }
 
   /**
@@ -186,7 +203,10 @@ public:
    * This includes timers or anything else that is initiated from user input.
    * However, mouse hover events are not counted as user input, nor are
    * page load events. If this method is called from asynchronously executed code,
-   * such as during layout reflows, it will return false.
+   * such as during layout reflows, it will return false. If more time has elapsed
+   * since the user input than is specified by the
+   * dom.event.handling-user-input-time-limit pref (default 1 second), this
+   * function also returns false.
    */
   NS_IMETHOD_(PRBool) IsHandlingUserInputExternal() { return IsHandlingUserInput(); }
   
@@ -507,6 +527,8 @@ private:
 
   PRPackedBool m_haveShutdown;
 
+  // Time at which we began handling user input.
+  static TimeStamp sHandlingInputStart;
 
 public:
   static nsresult UpdateUserActivityTimer(void);

content/html/content/test/test_fullscreen-api.html

@@ -5,6 +5,7 @@
   <script type="application/javascript" src="/MochiKit/packed.js"></script>
   <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
 </head>
 <body>
 <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=545812">Mozilla Bug 545812</a>
@@ -38,6 +39,23 @@ function run() {
   prevEnabled = SpecialPowers.getBoolPref("full-screen-api.enabled");
   SpecialPowers.setBoolPref("full-screen-api.enabled", true);
 
+  // Test requesting full-screen mode in a long-running user-generated event handler.
+  // The request in the key handler should not be granted.
+  window.addEventListener("keypress", keyHandler, false);
+  synthesizeKey("VK_A", {});
+}
+
+function keyHandler(event) {
+  window.removeEventListener("keypress", keyHandler, false);
+  
+  // Busy loop until 2s has passed. We should then be past the 1 second threshold, and so
+  // our request for full-screen mode should be rejected.
+  var end = (new Date()).getTime() + 2000;
+  while ((new Date()).getTime() < end) {
+    ; // Wait...
+  }
+  document.body.mozRequestFullScreen();
+
   prevTrusted = SpecialPowers.getBoolPref("full-screen-api.allow-trusted-requests-only");
 
   // Request full-screen from a non trusted context (this script isn't a user

modules/libpref/src/init/all.js

@@ -3351,6 +3351,10 @@ pref("alerts.disableSlidingEffect", false);
 pref("full-screen-api.enabled", false);
 pref("full-screen-api.allow-trusted-requests-only", true);
 pref("full-screen-api.key-input-restricted", true);
+
+// Time limit, in milliseconds, for nsEventStateManager::IsHandlingUserInput().
+// Used to detect long running handlers of user-generated events.
+pref("dom.event.handling-user-input-time-limit", 1000);
  
 //3D Transforms
 pref("layout.3d-transforms.enabled", false);