[Konsole-devel] Re: [PATCH] KAction (Was: [Bug 50342] konsole crash when quitting)

[Waldo Bastian]

On Wednesday 27 November 2002 18:59, Waldo Bastian wrote:
> The following patch fixes the problem for me. It is not really clear to me
> why the sequence of events in the bugreport trigger this bug, Maybe there
> is something else wrong as well?
>
> Short description:
> m_parentCollection is a normal pointer to a KActionCollection and does not
> become null when the KActionCollect gets deleted. However, the QObject
> destructor, called as part of the KActionCollection destructor, deletes
> all child objects (among them KAction objects) and resets parent() before
> deleting them. So if parent() is null, the KAction object is being deleted
> as part of the m_parentCollection destructor and m_parentCollection
> shouldn't be any longer used.
>
> Hmm.. what do we have here.... I guess this means there is something else
> wrong as well, because there is code in ~KActionCollection that resets
> pAction->m_parentCollection and that fails to work for some reason.

OK, what's wrong is that there can be multiple "unnamed" KAction's and that 
KActionCollection::_take() uses the name to index the dict. With multiple 
KAction's with the same name it can happen that it takes out the wrong one.

See e.g. this backtrace:
#2  0x40455e2a in KActionCollection::_take(KAction*) (this=0x8057448, 
action=0x80f1938) at kaction.cpp:3329
#3  0x40455f40 in KActionCollection::take(KAction*) (this=0x8057448, 
action=0x80f1938) at kaction.cpp:3351
#4  0x40442727 in ~KAction (this=0x80f1938) at kaction.cpp:285
#5  0x4028281f in QPtrList<KAction>::deleteItem(void*) (this=0xfffffffc, 
d=0x4120ff70)
    at /home/bastian/cvs/qt-copy/include/qptrlist.h:119
#6  0x40d0d31f in QGList::clear() (this=0x80bfe14) at tools/qglist.cpp:705
#7  0x4008226c in KonsoleBookmarkMenu::refill() (this=0x80bfdb8) at 
/home/bastian/cvs/qt-copy/include/qptrlist.h:78

Revised patch attached.

Cheers,
Waldo
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