Re: [xml] Incorrect processing of embedded script|style tags in RECOVERY mode.

["Andrey C. (aka mohmad)" <acauxer googlemail com>]

Greetings,

Daniel Veillard wrote:
> > In recovery mode, parent 'script' or 'style' section will be parsed 
> > wrongly if it  contains the same embedded one.
> > Say, an HTML document contains following script section:
> > ================================Cut here===================================
> > <script language=javascript>
> > ...
> > document.write('<script language=vbscript\>blah</script\>');
> > ...
> > </script>
> > ================================Cut here===================================
> > It's content escaped incorrectly.
> >
> >
> > After this document processed with HTML SAX Parser in RECOVERY mode, the 
> > original section looks corrupted:
> > ================================Cut here===================================
> > <script language=javascript>
> > ...
> > document.write('<script language=vbscript\>blah</script>
> > ================================Cut here===================================
> >
> > Cause both, the parent tag and the embedded one have similar names, the 
> > Parser breaks
> > parent section parsing prematurely, once it met the end of the embedded 
> > section.
> > (see HTMLparser.c, htmlParseScript function, line 2689).
>
>   Well I'm sure that HTML breaks in a number of places, not just in libxml2
> looks to me a case of broken beyond recovery data.
>
> > Possible patch is attached.
>
>   Could you try to explain your patch in english, i.e. what kind of workaround
> you suggest, this may help discuss it,

In RECOVER mode, during script|style tags processing, the patch counts number of embedded tags which are have name similar to the parent's one.
Processing of script|style tag breaks only if the counter isn't greater than zero, otherwise it's assumed that the end of embedded script|style tag has been reached and it's being treated as CDATA.

Pseudo code:
htmlParseScript()
{
  mtags = 0;
  tagname = {script|style};

  if ((cur == '<'))
  {
     if ((NXT(1) == '/'))
     {
        if (recovery && curtagname == tagname)
           if (mtags-- <= 0)
              break; // the end of tag being processed
     } else if (recovery && curtagname == tagname)
        ++mtags; // the same embedded tag
  }

  // treat parsed content as CDATA
}

Andrey.