July 2018 - webkit-dev - lists.webkit.org

PSA: Bit fields won't be packed on Windows if you mix types
by Ryosuke Niwa 04 Sep '20

04 Sep '20

Hi, Unlike gcc and clang, MSVC pads each consecutive member variables of the same type in bitfields. e.g. if you have: struct AB { unsigned m_1 : 31; bool m_2 : 1; } then *MSVC pads m_1 and allocates sizeof(unsigned) * 2 for AB* whereas gcc and clang only allocate sizeof(unsigned) * 1 for AB. This is *not a compiler bug*. It's a spec. compliant behavior, and may in fact have a better run-time performance in some situations. However, for core objects like RenderObject and InlineBox, allocating extra 4-8 bytes per each object is prohibitory expensive. In such cases, please *use the same POD type for all bitfield member variables*. (Storage class classifiers and variable qualifiers seem to have no effect on how variables are packed; e.g. mutable, const, etc...). For example, MSVC will allocate sizeof(unsigned) * 1 for AB if we rewrite the above code as: struct AB { unsigned m_1 : 31; unsigned m_2 : 1; } When you're making this change, *be sure to audit all code that assigns a non-boolean value to m_2* because implicit type coercion into boolean is no longer in effect. For example, AB ab; ab.m_2 = 2; puts(ab.m_2 ? "true" : "false"); will print "true" before the change and will print "false" after the change. An easy way to ensure you've audited all such code is to add getters and setters for all bitfield member variables or wrap them in a special structure or class as done in http://trac.webkit.org/changeset/103353 and http://trac.webkit.org/changeset/104254. Best regards, Ryosuke Niwa Software Engineer Google Inc.

4 8

Support "registerProtocolHandler" in WebKit2
by Gyuyoung Kim 20 Apr '20

20 Apr '20

Hello, I would like to listen what do you think to support 'registerProtocolHandler' in WebKit2. This feature is to execute web content through registered custom protocol. - For example, web content can register "mailto" custom protocol using this feature, <script> navigator.registerProtocolHandler("mailto", "https://mail.naver.com/", "Web Mail"); </script> <html> <head> <title>Web Protocol Handler Sample - Test</title> </head> <body> <p>Send an email : <a href="mailto://">this !</a></p> </body> </html> Besides this feature has been supported by Mozilla and Chromium (From Mozilla 3.0, Chromium 13). - https://developer.mozilla.org/en-US/docs/Web/API/Navigator/registerProtocol… - https://developer.mozilla.org/en/docs/Web-based_protocol_handlers The feature is included in the W3C recommendation 28 released on Oct. 2014. - W3C spec : http://www.w3.org/TR/html5/webappapis.html#custom-handlers IIRC, some WebKit1 ports supported this feature though, those ports were deprecated. Now WebKit port supports this feature no more. There is a very old bug to support this feature though, it wasn't maintained so far. Recently I updated it based on latest WebKit. - https://bugs.webkit.org/show_bug.cgi?id=92749 Feel free to give me any feedback about this feature. Gyuyoung.

10 26

WebKit project in Coverity
by Carlos Alberto Lopez Perez 09 Jan '20

09 Jan '20

Hi, Coverity is an static analysis tool that allows to find bugs and vulnerabilities on the source code via static analysis. For open source projects, they offer free usage of their platform. The WebKit project is already registered there since a while. [1] To read the reports in detail or run new scans you have to be member of the WebKit project in Coverity. I happen to be one of the admins there, and I will happily grant you access to this platform if you are a WebKit committer (listed in contributors.json). So if you are interested in this, just send me an email requesting access. Regards ------- [1] https://scan.coverity.com/projects/webkit

2 1

C++17 is here. Should we use it?
by JF Bastien 26 Jun '19

26 Jun '19

Hello WebKilters, Our Chrome-y friends are considering the use of C++14 <https://groups.google.com/a/chromium.org/forum/?utm_medium=email&utm_source…>. I have to say that C++14 in WebKit has been quite amazing, and we should consider using C++17: it has many wonderful new things <https://github.com/tvaneerd/cpp17_in_TTs/blob/master/ALL_IN_ONE.md>, some of which we already use through WTF’s re-implementation of library features. By now (table as witness <http://en.cppreference.com/w/cpp/compiler_support>) most C++17 languages features are in clang and GCC, and MSVC isn’t doing too bad either. Language things can just come through WTF if we really want them. So how about it? JF

8 23

For your consideration: Naming scheme for fooIfExists/ensureFoo
by Darin Adler 22 Feb '19

22 Feb '19

Lets bike shed! For some time, functions with names like fooIfExists and ensureFoo have been bothering me. I find both names kind of opaque and unpleasant. Here’s an example: StyleResolver* styleResolverIfExists(); StyleResolver* ensureStyleResolver() What do you think of these names instead? StyleResolver* optionalStyleResolver(); StyleResolver& requiredStyleResolver(); I like them better. Note also that I think the requiredStyleResolver function should return a reference so nobody is tempted to do null checks. It seems like the C++ community likes the name optional for this concept; isn’t there some kind of std::optional template? -- Darin

15 25

CSSOM View behavior for scrollLeft, scrollTop, scrollWidth etc
by Frédéric Wang 24 Sep '18

24 Sep '18

Hi everybody, I'd like to announce that I started to implement the behavior for scrollLeft, scrollTop, scrollWidth, scrollHeight, scrollTo, scrollBy and scrollingElement [1] as specified by the CSSOM View specification [2]. To summarize, the main difference is which element to use in order to set or get the scroll properties of the viewport in standard (non-Quirks) mode: * The CSSOM View spec says it should be document.documentElement and most browsers implement it that way. * Chromium used to use document.body but this has recently been changed to follow the CSSOM View spec [3]. * WebKit still uses document.body and I'm proposing to change this behavior. Note that this is likely to break existing content. The change was attempted in WebKit in the past but broke some non-regression tests [4]. Chromium people also had some issues when trying to ship the change but things went well at the end [5]. For now I'm developing it under a CSSOMViewScrollingAPI developer flag. I was able to run the tests with that flag enabled, modulo a few test adjustments. [1] https://bugs.webkit.org/show_bug.cgi?id=5991 [2] https://drafts.csswg.org/cssom-view [3] https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/X64Sg16RhT4 [4] https://bugs.webkit.org/show_bug.cgi?id=106133, https://bugs.webkit.org/show_bug.cgi?id=121876 [5] https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/2iOz5-fgD8Y/… ; https://bugs.webkit.org/show_bug.cgi?id=5991#c20 -- Frédéric Wang - frederic-wang.fr

1 3

Proposal: Not supporting x86 w/o SSE2
by Yusuke SUZUKI 04 Aug '18

04 Aug '18

Hello WebKittens, To mitigate recent side-channel attacks, we added `lfence` in x86 WebKit. But this is supported in x86 SSE2. So the ToT WebKit is not usable with very old x86 CPUs which do not have SSE2[1]. According to [2], Mozilla Firefox 49 no longer supports x86 w/o SSE2. Since Firefox 45 ESR is already End of Life, all the supported Firefox require SSE2 on x86. Chromium also does not support x86 if it does not have SSE2 IIRC[3]. So, no major browsers support x86 w/o SSE2 right now. I think our stakeholders do not maintain non-SSE2 x86. Even if it works, it is potentially vulnerable, and I think it is not acceptable for the browser engine. My proposal here is clarifying that WebKit does not support x86 not having SSE2. [1]: https://bugs.webkit.org/show_bug.cgi?id=188145 [2]: https://support.mozilla.org/en-US/kb/your-hardware-no-longer-supported [3]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=763290

3 3

Fujii Hironori is now a WebKit reviewer
by Michael Catanzaro 15 Jul '18

15 Jul '18

Hi, Fujii Hironori is now a WebKit reviewer. He has expertise in Windows support, WebKitGTK+, and WebCore bugs. Please congratulate him and send him patches to review! Michael

5 4

2018 WebKit Contributors Meeting - Save the Date
by Jonathan Davis 12 Jul '18

12 Jul '18

Hello WebKit Contributors, You are invited to attend the annual WebKit Contributors Meeting to be held at the Hyatt House San Jose/Silicon Valley hotel on Friday, October 12th, 2018 from 8 AM to 6 PM Pacific. Breakfast and sign-in will begin at 8 AM. Presentations will run between 9:30 AM to 6 PM. Lunch will be provided with all day coffee, tea and a mid-afternoon snack break. A reception is planned at the venue after the meeting with drinks and snacks from 6 PM to 9 PM. To attend you must be an active WebKit contributor. The meeting will be free of charge, and registration will open shortly. The event format will include a mix of proposed talks of around 40 minutes long and spontaneous lightning talks about 5-10 minutes long. If you have a topic idea that you want to present, please email me directly.. We look forward to seeing you there! Thank you, Jon Davis

1 0

EWS for security bugs
by Daniel Bates 12 Jul '18

12 Jul '18

Hi all, All Mac and iOS EWS bots now process security bug patches. We are working to configure the Apple Windows EWS bots and the WinCairo EWS bots should follow shortly. I do not know who maintains the GTK and WPE EWS bots. If you maintain one of these bots then please email me directly so that we can get you setup. For now, EWS processing of security patches is limited to the bubble status and the results posted to webkit-queues.webkit.org. That is, the EWS bots will not post comments to- or upload result archives to- security bugs. Also, we do not support using commit-queue for landing security patches at the moment. Help keep the tree green! Dan

3 2