Re: KBabel project crashes

Dňa Ne 29. Január 2006 19:44 Nicolas Goutte napísal:
> In KDE Bugs, there are a few bug report about crashes closely related to
> KBabel's projects.
>
> I think that I have finally found the main reason. The core of the problem
> is that the class Project (defined in kdesdk/kbabel/common/kbproject.h)
> inherits from KShared (defined in kdelibs/kdecore/ksharedptr.h).
>
> KShared-derived classes are supposed to be maily handled by the KSharedPtr
> class (also defined in kdelibs/kdecore/ksharedptr.h), which handles the
> reference counter of the KShared-dereived class.
>
> Unfortunately KBabel's ProjectManager class (defined in
> kdesdk/kbabel/common/ kbprojectmanager.h) does not handle the Project class
> with the care needed by a KShared-deried class.
>
> A KShared-class should be refered and derefered either implicetly by the
> KSharePtr or by calling explicitely the needed functions in KShared.
>
> Unfortunately, ProjectManager::open creates a Project object with new and
> assign it to a KSharedPtr and put that project pointer to QPtrList. However
> at the end of the function the KSharedPtr is destructed too and the
> reference count of the Project object is brought to zero and the project
> object is deleted. So the QPtrList pointer is becoming dangling, main
> reason of the crashes.
>
> *
>
> So now that I have found the problem, I do *not* have a solution,
> especially a binary compatible one. I had tried something by explicitely
> refering and derefering in ProjectManager but missed that we have no
> derefering function. (ProjectManager::remove is not such a function.)
>
> So I am not sure what to do. May be you have an idea.
>
> Introducing a function in ProjectManager for dereferencing is perhaps a way
> to go but I do not know how much code needs to be changed elsewhere (nor
> its impact on potentially existing third party programs for KBabel, as the
> Project and ProjectManager classes are supposed to be blubic, as their
> header files are installed.

I would not worry too much about publicity of the API. I've never heard of any 
use of KBabel core as a library.

Stano
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