id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
5876	Serialization - tracking of non-versioned classes	ybungalobill@…	Robert Ramey	"I quote a case from my workplace. The issue came up for std::vector<int>, but I use a simple struct X to reproduce the problem. See the attached file for detailed instructions.

Opened by Yakov Galka 9/8/2011 (Today) 8:31 AM Edit

The following code:

{{{
    struct X { ... };

    X x2;
    BoostLoad(""SerializationBug.dat"", x2);

#if FLAG
    volatile int x = 0;
    if(x)
    {
        X *x3;
        BoostLoad(""this code is never executed"", x3);
    }
#endif
}}}

Produces different results depending on whether FLAG == 0 or 1, although it's clear that it must not change it's behavior.

After some research it happens that the handling of tracking level is broken in boost since at least boost 1.46.1.

Assigned to Yakov Galka by Yakov Galka 9/8/2011 (Today) 8:31 AM
Notified ######.

Edited by Yakov Galka 9/8/2011 (Today) 8:53 AM [Revised 11:44 AM] Edit

It happens for objects with implementation level of object_serializable. That is:

{{{
BOOST_CLASS_IMPLEMENTATION(X, boost::serialization::object_serializable)
}}}

For greater implementation level, the tracking level is read from the archive. However it still must affect the saving of objects to any archives (binary, xml, text).

If it's not clear enough, the above code reads/writes the the file correctly when FLAG == 0, but tries to load x2 as-if it's tracked when FLAG == 1.

Edited by Yakov Galka 9/8/2011 (Today) 10:38 AM Edit
I've successfully reproduced this same bug in boost 1.33.1, although there it's silent (no crash, just wrong data is read). Boost serialization is broken really hard on the low-level:

basic_iserializer::tracking() decides whether the class should be tracked or not based on m_bpis value. However it can't decide this based on the information it has, since it's shared among objects serialized trough a pointer and not through a pointer.

Possible Fix: make basic_iserializer::tracking return the tracking level instead of a boolean value and let the caller decide what this tracking level means. It's a lot of work, and it may break computability with archives serialized incorrectly in 1.33.1, which happens to be possible. We are screwed anyway.

Edited by Yakov Galka 9/8/2011 (Today) 11:44 AM

Revised Yakov Galka's 8:53 AM entry from 9/8/2011"	Bugs	assigned	To Be Determined	serialization	Boost 1.47.0	Showstopper			mika.fischer@…