[webkit-dev] CSS Parse error in <link rel> element.

Thu Feb 9 08:45:54 PST 2017

What WebKit revision are your sources based on? It's quite likely the this bug has been fixed.

Simon

> On Feb 9, 2017, at 4:09 AM, Atul Sowani <sowani at gmail.com> wrote:
> 
> Finally I zeroed in on 3 "calc" candidates from the stylesheet which are causing the CSS parser to fail:
> 
> height:calc(100vh - 200px)
> height:calc(100vh - 230px)
> max-height:calc(100vh - 200px)
> 
> I think it is the very first one and the remaining two never get processed.
> 
> I put in some debug statements in the code and the corresponding output for this is:
> 
> ATUL: value->id = 0 propId = 1080
> ATUL: in CSSPropertyHeight
> ATUL: in CSSPropertyWebkitLogicalHeight
> ATUL: in CSSCalcValue::create
> ATUL: in parseValueExpression, calling parseAdditiveValueExpression
> ATUL: calling CSSCalcBinaryOperation::create from parseAdditiveValueExpression
> ATUL: operatorCharacter = -
> ATUL: lhs = 1 rhs = 1
> ATUL: leftSide category = ATUL: m_category = 5
> 5
> ATUL: rightSide category = ATUL: m_category = 1
> 1
> ATUL: m_category = 5
> ASSERTION FAILED: leftSide->category() != CalcOther && rightSide->category() != CalcOther
> css/CSSCalculationValue.cpp(293) : static WTF::PassRefPtr<WebCore::CSSCalcBinaryOperation> WebCore::CSSCalcBinaryOperation::create(WTF::PassRefPtr<WebCore::CSSCalcExpressionNode>, WTF::PassRefPtr<WebCore::CSSCalcExpressionNode>, WebCore::CalcOperator)
> 1   0x12e8a80c bin/phantomjs() [0x12e8a80c]
> < stack trace removed >
> 
> So the question is, is the calc expression valid one?
> 
> Best regards,
> Atul.
> 
> On Thu, Feb 9, 2017 at 2:17 PM, Atul Sowani <sowani at gmail.com <mailto:sowani at gmail.com>> wrote:
> @Konstantin thanks for the suggestions. I disabled CSS JIT on x85 but there was no negative impact on the results on x86. So I guess the issue is a genuine ppc64le problem. I have picked up the starting points mentioned in this thread earlier and debugging the issue. I have also isolated the issue to a single CSS file which is causing the problem. Now I am trying to isolate the exact entry in the CSS file which is causing the trouble.
> 
> Thanks!
> Atul.
> 
> On Tue, Feb 7, 2017 at 3:53 PM, Konstantin Tokarev <annulen at yandex.ru <mailto:annulen at yandex.ru>> wrote:
> 
> 
> 07.02.2017, 12:55, "Atul Sowani" <sowani at gmail.com <mailto:sowani at gmail.com>>:
> > Thanks Geoffrey, Alex, Yoav for the debugging pointer. I am debugging the issue further using this information and will most likely need some more help in immediate future as well.
> >
> > Unfortunately, I don't have a stand-alone test case which can be tested with qtwebkit. I am trying to load a page using PhantomJS and it's crashing. The typical URLs which cause it to crash are http://engadget.com <http://engadget.com/> and http://cnn.com <http://cnn.com/> - both of these load without any issue on x86 platform though, so the issue seems to be specific to ppc64le.
> 
> A few suggestions:
> 
> 1. I suppose you are building with disabled JIT, as WebKit does not implement JIT for any PPC variant in official tree. This may introduce subtle differences in behavior, for example I once encountered layout test that was failing only when CSS JIT was disabled. You can try building without JIT on x86_64 and compare.
> 
> 2. It might be miscompilation, as your platform may not be as thoroughly tested as more mainstream ones. You can try to build with -O0, -O1, -O2 (default is -O3). Alternatively, try building with different compiler (at least GCC and Clang support ppc64le and are fine for WebKit, xlC may not work though), or try different version of your compiler.
> 
> 3. Note that webkit-qt list is more appropriate for issues specific for QtWebKit. Make sure you are using latest release (technology preview 5 at the moment [1])
> 
> [1] https://github.com/annulen/webkit/releases/tag/qtwebkit-tp5 <https://github.com/annulen/webkit/releases/tag/qtwebkit-tp5>
> 
> >
> > Thanks,
> > Atul.
> >
> > On Mon, Feb 6, 2017 at 5:56 PM, Yoav Weiss <yoav at yoav.ws <mailto:yoav at yoav.ws>> wrote:
> >> Hi Atul,
> >>
> >> I second Alex's suggestion (perhaps followed by HTMLLinkElement::process() and other places in that file that refer to `hrefAttr`).
> >> If you have a test case online, I could try to take a look and maybe provide more guidance.
> >>
> >> Cheers :)
> >> Yoav
> >>
> >> On Fri, Feb 3, 2017 at 9:19 PM Alex Christensen <achristensen at apple.com <mailto:achristensen at apple.com>> wrote:
> >>> I would start looking at HTMLLinkElement::parseAttribute.
> >>> LinkHeader.cpp contains parsers for link headers, which are related.  Yoav knows more about those.  Those parsers ought to be united more.
> >>>
> >>>> On Feb 3, 2017, at 1:17 AM, Atul Sowani <sowani at gmail.com <mailto:sowani at gmail.com>> wrote:
> >>>> At present I am focusing on CSSParser::findURI() particularly and CSSParser::realLex() other related functionality in CSSParser.cpp - hope I am on right track. ;-)
> >>>>
> >>>> Please let me know if I should be looking at some other functionality as well to resolve this issue.
> >>>>
> >>>> Thanks!
> >>>> Atul.
> >>>>
> >>>> On Fri, Feb 3, 2017 at 2:33 PM, Atul Sowani <sowani at gmail.com <mailto:sowani at gmail.com>> wrote:
> >>>>> Hi,
> >>>>>
> >>>>> I came across an issue in qtwebkit CSS parser while working on a PhantomJS crash. The issue seems to be with parsing of <link rel="..." href="..."> type elements in an HTML page. What I observed is that the parser is trying to interpret the value for href given inside double-quotes. The value contains a "-" (e.g. "http://some.domain.com/some-page-etc-etc <http://some.domain.com/some-page-etc-etc>"). The "-" sign is being interpreted as minus and then things go wrong. In another case I found that "\g" embedded in the value (e.g. "http://some.domain.com/some-page/global/something <http://some.domain.com/some-page/global/something>") is also creating issues. In essence, the parser is trying to interpret the value, which I believe, it should not.
> >>>>>
> >>>>> I am willing to dive further into it to debug and fix the issue, but looking at the complexity and size of WebCore, I think I would benefit a lot to expedite a fix, if I could get some tips about which code area/functionality I should specifically focus in the WebCore. Looking forward to some help in this regard.
> >>>>>
> >>>>> Thanks,
> >>>>> Atul.
> >>>> _______________________________________________
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> > ,
> >
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> 
> 
> -- 
> Regards,
> Konstantin
> 
> 
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