Re: [xml] A rare bug?

[Daniel Veillard <veillard redhat com>]

On Thu, Jan 03, 2008 at 03:34:07PM -0800, David Zhuo wrote:
>    hi All,
>    I have a schema and a XML file and used xmllint to verify that the XML
>    is  in  fact confirm to the schema. The rare problem I am running into
>    is that different version of xmllint will have very different behavior
>    and I am not certain which version is at fault. Here is an example:
>    $ /usr/bin/xmllint --version
>    /usr/bin/xmllint: using libxml version 20620
>        compiled  with: DTDValid FTP HTTP HTML C14N Catalog XPath XPointer
>    XInclude Iconv Unicode Regexps Automata Schemas Modules
>    $ /usr/bin/xmllint --noout --schema
>    [1]http://www.youtube.com/xsd/metadata_0.2.xsd /tmp/test.xml
>    /tmp/test.xml validates
>    a new version 20623, however, fails:
>    $ /usr/bin/xmllint --version
>    /usr/bin/xmllint: using libxml version 20623
>        compiled  with:  Threads  Tree  Output Push Reader Patterns Writer
>    SAXv1  FTP  HTTP  DTDValid  HTML  Legacy  C14N  Catalog XPath XPointer
>    XInclude   Iconv   ISO8859X  Unicode  Regexps  Automata  Expr  Schemas
>    Schematron Modules Debug
>    $ /usr/bin/xmllint --noout --schema
>    [2]http://www.youtube.com/xsd/metadata_0.2.xsd /tmp/test.xml
>    /tmp/test.xml:18:  element  keywords: Schemas validity error : Element
>    '{  [3]http://search.yahoo.com/mrss}keywords':  [facet  'pattern'] The
>    value   'London,Sci   Fi,Aliens'   is  not  accepted  by  the  pattern
>    '(.*,){2,}.*'.
>    /tmp/test.xml:18:  element  keywords: Schemas validity error : Element
>    '{  [4]http://search.yahoo.com/mrss}keywords':  'London,Sci Fi,Aliens'
>    is not a valid value of the local atomic type.
>    /tmp/test.xml fails to validate
>    the  test  is  performed  with  the  same  XML and schema and the only
>    different  is  the  version  of  xmllint  used.  Build  version  20620
>    successfully validate the XML while version 20623 does not.
>    the  sample  XML  is attached. can someone tell me if this is a bug or
>    not?

  There have been some rather nasty bugs introduced, and then fixed in libxml2
regexp engine over the last 2 years. I really suggest you try with very recent
versions for XSD validation like 2.6.30

In your example it seems the regexp should match as your string includes at
least 2 commas, and indeed the latest version validates it:

laptop:~/XML -> ./testRegexp '(.*,){2,}.*' 'London,Sci   Fi,Aliens'
Testing (.*,){2,}.*:
London,Sci   Fi,Aliens: Ok
laptop:~/XML -> 


Daniel

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