RE: [xml] Possible bug with Byte Order Marks

["Mark.Itzcovitz" <mark itzcovitz vistacomp com>]

> > Returning to my original query, which was that xmlDocDumpMemory and
> > xmlDocFormatDump don't work correctly for "UTF-16", and having looked
> more
> > closely at the code for those functions, I think that my proposed
> changes
> > have too broad a scope. I can see a different solution that can easily
> be
> > applied to those two functions but I am confused by what seems to me to
> be
> > an inconsistency, as follows:
> >
> > A call to xmlFindCharEncodingHandler for "UTF-16" fails.
> > A call to xmlParseCharEncoding for "UTF-16" followed by a call to
> > xmlGetCharEncodingHandler returns the handler for
> XML_CHAR_ENCODING_UTF16LE.
>
>   the problem is that you add some state information, if you can keep this
> in
> the local variables of the serialization routine then that's fine.
>
> > The two Dump functions call xmlParseCharEncoding followed by
> > xmlFindCharEncodingHandler. I propose putting a call to
> > xmlGetCharEncodingHandler (using the result from the call to
> > xmlParseCharEncoding), and only calling Find if the Get fails. This is
> > hopefully a safe change.
>
>   Hum, sounds better, could you give a patch ?

This is the patch:

In xmlDocFormatDump in tree.c:
Was:
        if (enc != XML_CHAR_ENCODING_UTF8) {
          handler = xmlFindCharEncodingHandler(encoding);
            if (handler == NULL) {

Now:
        if (enc != XML_CHAR_ENCODING_UTF8) {
            handler = xmlGetCharEncodingHandler(enc);
            if (handler == NULL)
                handler = xmlFindCharEncodingHandler(encoding);
            if (handler == NULL) {

In xmlDocDumpFormatMemoryEnc in tree.c:
Was:
        } else if (doc_charset != XML_CHAR_ENCODING_UTF8) {
            conv_hdlr = xmlFindCharEncodingHandler(txt_encoding);
            if ( conv_hdlr == NULL ) {

Now:
        } else if (doc_charset != XML_CHAR_ENCODING_UTF8) {
            conv_hdlr = xmlGetCharEncodingHandler(doc_charset);
            if (conv_hdlr == NULL)
                conv_hdlr = xmlFindCharEncodingHandler(txt_encoding);
            if ( conv_hdlr == NULL ) {


I'm still not 100% convinced that this is the correct way to go, but at
least it hopefully won't break anything. Another alternative would be, in
xmlInitCharEncodingHandlers, to register a handler for UTF-16 to be the same
as the handler for UTF-16LE or to create an alias of UTF-16 for UTF-16LE,
but I don't have the experience of libxml to know about any implications
this might have.

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