Bug 10341 – SVGs fail to render intermittently (on reload)

• Component: SVG
• Status: RESOLVED WONTFIX

[Eric Seidel (no email)]

REGRESSION: All embedded SVGs fail to render intermittently (on reload)They fail out due to a libxml error.  I've seen this error before, and I believe it happens when you call switchEncoding when you don't actuallly have any data to write.

error on line 1 at column 1: switching encoding : no input

[Eric Seidel (no email)]

Wow, strange enough this is still an issue. :(  I'm testing with r16339.

[Eric Seidel (no email)]

This is still a (really bad!) problem on TOT.  Although since WebKit has never officially shipped SVG, I'm not sure this can be a P1 regression.

[Stephanie Lewis]

Radar <rdar://problem/4959694>

[Maciej Stachowiak]

Removing regression tag and downgrading to P2 per Eric's comments.

[Eric Seidel (no email)]

*** Bug 13188 has been marked as a duplicate of this bug. ***

[Eric Seidel (no email)]

I'm seeing this on http://www.carto.net/papers/svg/samples/matrix.svg just now as well.

[Eric Seidel (no email)]

I suspect this is related to the encoding switching we do to work around another libxml bug:

void XMLTokenizer::doWrite(const String& parseString)
{
    if (!m_context)
        initializeParserContext();
    
    // libXML throws an error if you try to switch the encoding for an empty string.
    if (parseString.length()) {
        // Hack around libxml2's lack of encoding overide support by manually
        // resetting the encoding to UTF-16 before every chunk.  Otherwise libxml
        // will detect <?xml version="1.0" encoding="<encoding name>"?> blocks 
        // and switch encodings, causing the parse to fail.
        const UChar BOM = 0xFEFF;
        const unsigned char BOMHighByte = *reinterpret_cast<const unsigned char*>(&BOM);
        xmlSwitchEncoding(m_context, BOMHighByte == 0xFF ? XML_CHAR_ENCODING_UTF16LE : XML_CHAR_ENCODING_UTF16BE);

        xmlParseChunk(m_context, reinterpret_cast<const char*>(parseString.characters()), sizeof(UChar) * parseString.length(), 0);
    }
    
    if (m_doc->decoder() && m_doc->decoder()->sawError()) {
        // If the decoder saw an error, report it as fatal (stops parsing)
        handleError(fatal, "Encoding error", lineNumber(), columnNumber());
    }

    return;
}

[Eric Seidel (no email)]

Today I'm using:
Version 4.0 (5528.1)
ProductName:	Mac OS X
ProductVersion:	10.5.5
BuildVersion:	9F33

[Dirk Schulze]

I don't see problems on reload. But indeed it does not look correct. Like eric wrote, this is a bug with libxml and just occurs on MacOS right now. This should work, once Mac OS X has a newer version of libxml. I mark this as WONTFIX, since this is not a problem of WebKit. At least we don't want to add hacks as workaround for bugs in libxml.