Bug 63078 – REGRESSION (r88260): Assertion failure in FontCache::getCachedFontData when typing in Safari's address field

• Component: Text
• Status: RESOLVED FIXED

[Adam Roben (:aroben)]

To reproduce:

1. Type in Safari's address field while using a Debug build of WebKit

You'll hit an assertion in FontCache::getCachedFontData:

        ASSERT(m_purgePreventCount);

I don't know what the Release symptom is. Michael Saboff probably does.

Here's the backtrace:

>	WebKit.dll!WebCore::FontCache::getCachedFontData(const WebCore::FontPlatformData * platformData=0x0b050218, WebCore::FontCache::ShouldRetain shouldRetain=DoNotRetain)  Line 279 + 0x29 bytes	C++
 	WebKit.dll!WebCore::FontCache::getFontDataForCharacters(const WebCore::Font & font={...}, const wchar_t * characters=0x0012f3f0, int length=1)  Line 288 + 0x11 bytes	C++
 	WebKit.dll!WebCore::Font::glyphDataForCharacter(int c=8206, bool mirror=false, WebCore::FontDataVariant variant=NormalVariant)  Line 195 + 0x1e bytes	C++
 	WebKit.dll!WebCore::WidthIterator::advance(int offset=41, WebCore::GlyphBuffer * glyphBuffer=0x00000000)  Line 126 + 0x18 bytes	C++
 	WebKit.dll!WebCore::Font::floatWidthForSimpleText(const WebCore::TextRun & run={...}, WebCore::GlyphBuffer * glyphBuffer=0x00000000, WTF::HashSet<WebCore::SimpleFontData const *,WTF::PtrHash<WebCore::SimpleFontData const *>,WTF::HashTraits<WebCore::SimpleFontData const *> > * fallbackFonts=0x00000000, WebCore::GlyphOverflow * glyphOverflow=0x00000000)  Line 455	C++
 	WebKit.dll!WebCore::Font::width(const WebCore::TextRun & run={...}, WTF::HashSet<WebCore::SimpleFontData const *,WTF::PtrHash<WebCore::SimpleFontData const *>,WTF::HashTraits<WebCore::SimpleFontData const *> > * fallbackFonts=0x00000000, WebCore::GlyphOverflow * glyphOverflow=0x00000000)  Line 190 + 0x47 bytes	C++
 	WebKit.dll!WebCore::stringWidth(const WebCore::Font & renderer={...}, const wchar_t * characters=0x0a361484, unsigned int length=41)  Line 98 + 0x10 bytes	C++
 	WebKit.dll!WebCore::StringTruncator::width(const WTF::String & string={? Overview  Python v2.7.2 documentation}, const WebCore::Font & font={...})  Line 194 + 0x1b bytes	C++
 	WebKit.dll!WebCore::WebCoreTextFloatWidth(const WTF::String & text={? Overview  Python v2.7.2 documentation}, const WebCore::Font & font={...})  Line 104 + 0xd bytes	C++
 	WebKit.dll!TextFloatWidth(const wchar_t * text=0x0afccf54, int length=41, const WebFontDescription & description={...})  Line 126 + 0x27 bytes	C++

[Adam Roben (:aroben)]

Presumably the WebKitGraphics.cpp APIs need some FontCachePurgePreventer love.

[Adam Roben (:aroben)]

<rdar://problem/9648668>

[Geoffrey Garen]

The release build symptom is extra memory use, with a small risk of crash sprinkled in.

[Michael Saboff]

Created attachment 98120 [details]
Patch with additional FontCachePurgePreventer for ASSERT failure

Patch includes two other additional instances of purge prevention based on code inspection.
These changes are speculative.

[Adam Roben (:aroben)]

Comment on attachment 98120 [details]
Patch with additional FontCachePurgePreventer for ASSERT failure

I haven't been able to cause an assertion failure involving createDragImageForLink, but this seems fine to me.

[Adam Roben (:aroben)]

Comment on attachment 98120 [details]
Patch with additional FontCachePurgePreventer for ASSERT failure

I can confirm that this patch fixes the assertion I was seeing. Thanks!

[Michael Saboff]

Committed r89425: <http://trac.webkit.org/changeset/89425>