[Boost-bugs] [Boost C++ Libraries] #7240: serialization backward compatibility issue with class_id_type attribute

Subject: [Boost-bugs] [Boost C++ Libraries] #7240: serialization backward compatibility issue with class_id_type attribute
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-08-16 10:42:30

#7240: serialization backward compatibility issue with class_id_type attribute
-----------------------------------+----------------------------------------
 Reporter:  ggagniard@…            |       Owner:  ramey        
     Type:  Bugs                   |      Status:  new          
Milestone:  To Be Determined       |   Component:  serialization
  Version:  Boost 1.50.0           |    Severity:  Regression   
 Keywords:                         |  
-----------------------------------+----------------------------------------
 There is a backward compatibility issue in current boost::serialization
 around the class_id_type attribute.

 It is actually impossible to read binary archives written with boost 1.39
 (format 5) with a boost release > 1.43.

 For instance, with boost 1.47.0 :

 test_serialization:
 /home/ggagniard/dev/boost-1.47.0.bug/include/boost/archive/basic_archive.hpp:116:
 boost::archive::class_id_type::class_id_type(int): Assertion `t_ <=
 boost::integer_traits<base_type>::const_max' failed.

 Please note that the same error still occurs with boost 1.50.0, the
 current stable release.

 After having a look at the class_id_type serialization in binary archives,
 I think I found the culprit :

 In boost/archive/basic_binary_iarchive.hpp :

 {{{
     void load_override(class_id_type & t, int version){
         library_version_type lvt = this->get_library_version();
         if(boost::archive::library_version_type(7) < lvt){
             this->detail_common_iarchive::load_override(t, version);
         }
         else
         if(boost::archive::library_version_type(6) < lvt){
             int_least16_t x=0;
             * this->This() >> x;
             t = boost::archive::class_id_type(x);
         }
         else{
             int x=0;
             * this->This() >> x;
             t = boost::archive::class_id_type(x);
         }
     }
 }}}

 Here, archives whose version <= 6 get their class_id_type read as an int
 ...

 However, in boost 1.43 (format 7) :

 {{{
     void load_override(class_id_type & t, int){
         // upto 32K classes
         int_least16_t x=0;
         * this->This() >> x;
         t = class_id_type(x);
     }
 }}}

 It is clear than any library version <= 7 have their class_id_type
 serialized as a int_least16_t, so the current load_override method is
 incorrect for versions <= 6 ...

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7240>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.