[webkit-dev] [QtWebKit] exposing JScript Objects to Clients
Hi there,
At the moment WebKit does not deliberately expose any of the properties of
Javascript objects to clients. Those it does expose seem to be as much by
luck as anything else. One example is navigator.useragent, which in Qt's
case ultimately returns whatever the client has set in userAgentForUrl().
The more common case is illustrated by the other properties of the
navigator object. Here is the return value for navigator.appname as defined
in NavigatorBase.cpp:
String NavigatorBase::appName() const
{
return Netscape;
}
I would like to make it possible for the client to control the values
returned by JS objects - this is so that my project (http://torora.net) can
ensure that the anonymity set of torora's users is properly preserved. For
example, Torora would always ensure that the value returned for
navigator.platform would be 'WinXP' (regardless of the user's actual OS).
This would protect the user from a website collating information on a user
and possibly uniquely identifying them.[1]
The only way I can think of providing this API is as follows (taking the
navigator object as an example):
1. Copy WebCore/page/Navigator.cpp to WebCore/page/qt/NavigatorQt.cpp and
exclude Navigator.cpp from the Qt build.
2. In NavigatorQt.cpp implement the return values by calling virtual
functions in QWebPage. Following the example of userAgentForUrl() this
would take the form of:
String NavigatorBase::appName() const
{
String appName = m_frame-loader()-appName();
if (appName.isEmpty())
return NavigatorBase::appName();
return appName;
}
which calls:
String FrameLoaderClientQt::appName()
{
if (m_webFrame) {
return m_webFrame-page()-appName();
}
return String();
}
where page()-AppName() is a virtual function in QWebPage that returns an
empty string if it is not reimplemented by the client.
3. NavigatorQt.cpp would have to do this for all elements of the navigator
object that it wanted to offer for client control.
The same approach would have to be used for the date, screen and window
objects, though in the case of Torora there are other ways of ensuring
those values do not give away anything so my only actual requirement at the
moment is to control the navigator object,
I see a couple of disadvantages to this approach:
1. Likely performance hit.
2. Customized implementations of functions in the qt/ folder of the
WebCore/page directory are for functions not implemented at all in the base
code, rather than for replacing the ones that are.
3. It's a very cumbersome way of doing things.
A proper hooking mechanism (where clients could control all javascript
objects) for javascript would seem to require a major overhaul to
webcore/javascriptcore, and I have no idea how it would work or even if it
would be possible.
So my questions are:
- Is the above approach acceptable for QtWebKit?
- Is there any effort already underway for a hooking mechanism for jscore?
- Is there an alternative approach anyone can think of?
[1] Torora already does this by providing a patch to webkit when building
from source. The patch crudely overrides existing values with a 'safe' set
of hardcoded values.
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Re: [webkit-dev] Custom HTML Tags
Sounds like you want XBL. :) On Mon, Sep 28, 2009 at 8:27 PM, Chris Frost chrisfros...@gmail.com wrote: Hello All, I am thinking about creating some custom HTML tags to abstract the process of creating graphical widgets such as clock and calendar. To make it work, I would imagine I need some interpreter to transform the custom tags to HTML/CSS/JS before rendering the page. I heard a lot of great things about Webkit, but I am quite new to its codebase. I am wondering if Webkit is the right technology to solve my problem. Any pointers would be very much appreciated. Thank you in advance! Chris ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
Re: [webkit-dev] [QtWebKit] exposing JScript Objects to Clients
If your goal is to specify the useragent string that can be done
entirely in the API layer without modifying WebCore at all (this is
how Mac browsers built on the system WebKit specify their app name).
The changes you're requesting should not involve WebCore in any way.
If you're wanting to manipulate the DOM that is purely a matter of
having a DOM binding for Qt or just getting the js global object and
using the standard JSC APIs to manipulate it.
--Oliver
On Sep 21, 2009, at 10:58 AM, Robert Hogan wrote:
Hi there,
At the moment WebKit does not deliberately expose any of the
properties of
Javascript objects to clients. Those it does expose seem to be as
much by
luck as anything else. One example is navigator.useragent, which in
Qt's
case ultimately returns whatever the client has set in
userAgentForUrl().
The more common case is illustrated by the other properties of the
navigator object. Here is the return value for navigator.appname as
defined
in NavigatorBase.cpp:
String NavigatorBase::appName() const
{
return Netscape;
}
I would like to make it possible for the client to control the values
returned by JS objects - this is so that my project (http://
torora.net) can
ensure that the anonymity set of torora's users is properly
preserved. For
example, Torora would always ensure that the value returned for
navigator.platform would be 'WinXP' (regardless of the user's actual
OS).
This would protect the user from a website collating information on
a user
and possibly uniquely identifying them.[1]
The only way I can think of providing this API is as follows (taking
the
navigator object as an example):
1. Copy WebCore/page/Navigator.cpp to WebCore/page/qt/
NavigatorQt.cpp and
exclude Navigator.cpp from the Qt build.
2. In NavigatorQt.cpp implement the return values by calling virtual
functions in QWebPage. Following the example of userAgentForUrl() this
would take the form of:
String NavigatorBase::appName() const
{
String appName = m_frame-loader()-appName();
if (appName.isEmpty())
return NavigatorBase::appName();
return appName;
}
which calls:
String FrameLoaderClientQt::appName()
{
if (m_webFrame) {
return m_webFrame-page()-appName();
}
return String();
}
where page()-AppName() is a virtual function in QWebPage that
returns an
empty string if it is not reimplemented by the client.
3. NavigatorQt.cpp would have to do this for all elements of the
navigator
object that it wanted to offer for client control.
The same approach would have to be used for the date, screen and
window
objects, though in the case of Torora there are other ways of ensuring
those values do not give away anything so my only actual requirement
at the
moment is to control the navigator object,
I see a couple of disadvantages to this approach:
1. Likely performance hit.
2. Customized implementations of functions in the qt/ folder of the
WebCore/page directory are for functions not implemented at all in
the base
code, rather than for replacing the ones that are.
3. It's a very cumbersome way of doing things.
A proper hooking mechanism (where clients could control all javascript
objects) for javascript would seem to require a major overhaul to
webcore/javascriptcore, and I have no idea how it would work or even
if it
would be possible.
So my questions are:
- Is the above approach acceptable for QtWebKit?
- Is there any effort already underway for a hooking mechanism for
jscore?
- Is there an alternative approach anyone can think of?
[1] Torora already does this by providing a patch to webkit when
building
from source. The patch crudely overrides existing values with a
'safe' set
of hardcoded values.
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[webkit-dev] about script plugin
Hello all
Now, I have a problem and I don't konw how to solve it, I hope you
help me, thank you!
I have written a scripting plugin with NPAPI and this plugin has
some properties and methods. it has a intValue property and two methods of
getValue and setValue. Now I don't konw when and where to call the
functions(NPN_Invoke(), NPN_GetProperty()) in NPAPI , Could you give me a
example?
thank you!
This is my web page for testing object plugin,please see the HTML code:
testObject.htm
html
head
titleplugin example/title
script type=text/javascript
function fun()
{
elem = document.getElementById(para1);
alert(elem.intValue);
var value = 5;
elem.setValue(value);
var intValue = elem.getValue();
alert(intValue);
}
/script
/head
body
object id=para1 type=clsid:72E6F181-D1B0-4C22-B0D7-4A0740EEAEF5
param name=bgcolor value=#c6cfd0 /
param name=jad value=Mp3/TestSound.jad /
param name=jar value= Mp3/TestSound.jar /
/object
button onclick=fun();Button/button
/body
/html
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Re: [webkit-dev] Leak reports during shutdown
Hi Kevin, WebKit approach is NOT to free memory before quit to make the quit process as fast as possible. The memory manager should free the unfreed objects. However, this approach makes really hard to find the real leaks (which are unreferenced objects). In my experince the unfreed (non-leak) objects come from several sources: - JavaScriptCore garbage collector is not called before quit - Caches are not cleared before quit The previous two are performed by QtLauncher in debug mode. See WebKit/qt/QtLauncher/main.cpp launcherMain() - In case of workers, the gc() does not called for each worker threads when the application quits. The JavaScript threads are simply aborted. - Global objects are not freed at all. There was an attempt to free them (see https://bugs.webkit.org/show_bug.cgi?id=27980 ) but seems not worth to continue that work, although it helped to find leaks such as this: https://bugs.webkit.org/show_bug.cgi?id=29295 The remaining unfreed objects are possible leaks. Many of them are probably port specific (not all port maintainers have resources to keep leak hunters). Zoltan Hi all, For a while, ports like wx and Win/Cairo have been seeing various leaks reported on shutdown, but at least on Mac I've been unable to see these leaks using memory leak checkers like the one in Instruments, so I decided to poke into the code a bit more and try to understand what's going on a bit better. What I found was that the reported object leaks were pretty much all related to objects that JSC has references to. Changing ~ScriptController to do a garbageCollectNow() instead of garbageCollectSoon(), for example, drastically reduced the number of reported leaks, cleaning up all the CachedResource leaks and almost all the WebCoreNode leaks. The remaining leaks were almost all JSC::Structure objects. I've been digging through the code to try and find the place where these JSC objects are finally deleted, but I haven't found anyplace obvious in the code, neither in common code nor in the ports' code. My question is, is there somewhere these objects are being deleted on final shutdown that apparently happens after the leaks are reported, or does WebKit have assumptions such as that all still running timers must fire before final shutdown that ports such as ours are not honoring? (e.g. in my tests garbageCollectSoon() does not end up firing the callback because the app shuts down too fast.) Thanks, Kevin ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
Re: [webkit-dev] Leak reports during shutdown
Some leak checkers are based on all objects being deleted at shutdown. Those won’t work with WebKit. It doesn’t delete all objects at shutdown. Other leak checkers are based on finding unreachable objects. Those work well with WebKit. -- Darin ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
Re: [webkit-dev] Leak reports during shutdown
Hi Zoltan, On Sep 29, 2009, at 12:39 PM, Zoltan Herczeg wrote: Hi Kevin, WebKit approach is NOT to free memory before quit to make the quit process as fast as possible. The memory manager should free the unfreed objects. However, this approach makes really hard to find the real leaks (which are unreferenced objects). In my experince the unfreed (non-leak) objects come from several sources: - JavaScriptCore garbage collector is not called before quit - Caches are not cleared before quit The previous two are performed by QtLauncher in debug mode. See WebKit/qt/QtLauncher/main.cpp launcherMain() - In case of workers, the gc() does not called for each worker threads when the application quits. The JavaScript threads are simply aborted. - Global objects are not freed at all. There was an attempt to free them (see https://bugs.webkit.org/show_bug.cgi?id=27980 ) but seems not worth to continue that work, although it helped to find leaks such as this: https://bugs.webkit.org/show_bug.cgi?id=29295 The remaining unfreed objects are possible leaks. Many of them are probably port specific (not all port maintainers have resources to keep leak hunters). Thanks for the detailed response, this makes things very clear! :-) ( thanks to Darin for his info about leak checkers) I guess I didn't really expect things to work this way in debug mode as it seems to me RefCountedLeakChecker pretty much needs those resources to be freed in order to provide useful leak reports. In any case, I've been thinking about adding some APIs to manage the cache to wxWebKit and now I've got even more of an incentive to code something up. :-) Thanks, Kevin Zoltan Hi all, For a while, ports like wx and Win/Cairo have been seeing various leaks reported on shutdown, but at least on Mac I've been unable to see these leaks using memory leak checkers like the one in Instruments, so I decided to poke into the code a bit more and try to understand what's going on a bit better. What I found was that the reported object leaks were pretty much all related to objects that JSC has references to. Changing ~ScriptController to do a garbageCollectNow() instead of garbageCollectSoon(), for example, drastically reduced the number of reported leaks, cleaning up all the CachedResource leaks and almost all the WebCoreNode leaks. The remaining leaks were almost all JSC::Structure objects. I've been digging through the code to try and find the place where these JSC objects are finally deleted, but I haven't found anyplace obvious in the code, neither in common code nor in the ports' code. My question is, is there somewhere these objects are being deleted on final shutdown that apparently happens after the leaks are reported, or does WebKit have assumptions such as that all still running timers must fire before final shutdown that ports such as ours are not honoring? (e.g. in my tests garbageCollectSoon() does not end up firing the callback because the app shuts down too fast.) Thanks, Kevin ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev ___ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
