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

[Atul Sowani]

I am using Qt 5.5.1.

On Thu, Feb 9, 2017 at 10:15 PM, Simon Fraser <simon.fraser at apple.com>
wrote:

> 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> 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>
>> wrote:
>>
>>>
>>>
>>> 07.02.2017, 12:55, "Atul Sowani" <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 and 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
>>>
>>> >
>>> > Thanks,
>>> > Atul.
>>> >
>>> > On Mon, Feb 6, 2017 at 5:56 PM, Yoav Weiss <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> 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> 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>
>>> 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"). 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-p
>>> age/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.
>>> >>>> _______________________________________________
>>> >>>> webkit-dev mailing list
>>> >>>> webkit-dev at lists.webkit.org
>>> >>>> https://lists.webkit.org/mailman/listinfo/webkit-dev
>>> > ,
>>> >
>>> > _______________________________________________
>>> > webkit-dev mailing list
>>> > webkit-dev at lists.webkit.org
>>> > https://lists.webkit.org/mailman/listinfo/webkit-dev
>>>
>>>
>>> --
>>> Regards,
>>> Konstantin
>>>
>>
>>
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