[Webkit-unassigned] [Bug 12947] REGRESSION: ASSERTION FAILED: maxWidth >= 0 in StringTruncator.cpp:109 in WebCore::truncateString()

[bugzilla-daemon at webkit.org]

http://bugs.webkit.org/show_bug.cgi?id=12947





------- Comment #4 from ddkilzer at webkit.org  2007-03-02 13:46 PDT -------
(In reply to comment #2)
> I cannot reproduce this on a PowerPC Mac.

The issue is most likely caused by differences in how NaN floating point values
are handled on PowerPC versus Intel architectures.  Obviously, this code from
StringTruncator.cpp (line 109) returns true with a NaN on PowerPC, but false
with a NaN on Intel:

     ASSERT(maxWidth >= 0);

I added an additional ASSERT() macro to the Intel debug build:

+    ASSERT(!isnan(maxWidth));
     ASSERT(maxWidth >= 0);

And rerunning the steps to reproduce demonstrated that maxWidth was a NaN
value:

ASSERTION FAILED: !isnan(maxWidth)
(/Users/dkilzer/Projects/WebKit/WebCore/platform/StringTruncator.cpp:109
WebCore::String WebCore::truncateString(const WebCore::String&, float, const
WebCore::Font&, unsigned int (*)(const WebCore::String&, unsigned int, unsigned
int, UChar*)))
Segmentation fault

Not sure if we need to determine where the NaN is generated, or simply handle
the NaN case differently in the truncateString(const String& string, float
maxWidth, const Font& font, TruncationFunction truncateToBuffer) method.


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