[Boost-bugs] [Boost C++ Libraries] #4809: deserialization with xml_iarchive fails when attributes of top level element are reordered

Subject: [Boost-bugs] [Boost C++ Libraries] #4809: deserialization with xml_iarchive fails when attributes of top level element are reordered
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-11-02 15:47:59

#4809: deserialization with xml_iarchive fails when attributes of top level
element are reordered
-----------------------------------------------+----------------------------
 Reporter:  Kolja Nowak <kolja@…>              |       Owner:         
     Type:  Bugs                               |      Status:  new    
Milestone:  To Be Determined                   |   Component:  None   
  Version:  Boost 1.44.0                       |    Severity:  Problem
 Keywords:  serialization xml attribute order  |  
-----------------------------------------------+----------------------------
 Citing from [http://www.w3.org/TR/2008/REC-xml-20081126/ W3C XML spec],
 section 3.1: "Note that the order of attribute specifications in a start-
 tag or empty-element tag is not significant."

 The parser used by xml_iarchive doesn't conform to this, because it fails
 on XML input which is logically equivalent to the output of xml_oarchive,
 just because the attribute order of the top level element
 'boost_serialization' was changed. In contrast, the parser seems to be
 robust against reordering attributes in other elements.

 The following program demonstrates the issue:
 {{{

 #include <iostream>
 #include <sstream>
 #include <string>
 #include <boost/archive/xml_iarchive.hpp>

 void f(const std::string& xml)
 {
   try
   {
     std::string str;
     boost::archive::xml_iarchive(std::istringstream(xml))
       >> boost::serialization::make_nvp("str", str);
     std::cout << str << std::endl;
   }
   catch(boost::archive::archive_exception& e)
   {
     std::cout << e.what() << std::endl;
   }
 }

 int main()
 {
   // deserialize some xml, which was created using xml_oarchive

   f("<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\" ?>"
     "<!DOCTYPE boost_serialization>"
     "<boost_serialization signature=\"serialization::archive\"
 version=\"7\">"
     "<str>deserialize successfull</str>"
     "</boost_serialization>");

   // the same xml, but attributes of <boost_serialization> reorderd

   f("<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\" ?>"
     "<!DOCTYPE boost_serialization>"
     "<boost_serialization version=\"7\"
 signature=\"serialization::archive\">"
     "<str>deserialize successfull</str>"
     "</boost_serialization>");

   return 0;
 }
 }}}

 The following patch to basic_xml_grammar.ipp modifies the rule
 'SerializationWrapper' to accept both possible combinations:

 {{{
 Index: libs/serialization/src/basic_xml_grammar.ipp
 ===================================================================
 --- libs/serialization/src/basic_xml_grammar.ipp    (revision 66354)
 +++ libs/serialization/src/basic_xml_grammar.ipp    (working copy)
 @@ -271,9 +271,9 @@
        =  -S
        >> "<boost_serialization"
        >> S
 -      >> SignatureAttribute
 -      >> S
 -      >> VersionAttribute
 +      >> ( (SignatureAttribute >> S >> VersionAttribute)
 +         | (VersionAttribute >> S >> SignatureAttribute)
 +         )
        >> !S
        >> '>'
      ;
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4809>
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