[wx-dev] #9708: wxEvtHandler - Dead event table entry used in ProcessEvent

[wxTrac]

Ticket URL: <http://trac.wxwidgets.org/ticket/9708>

#9708: wxEvtHandler - Dead event table entry used in ProcessEvent
---------------------------------------------+------------------------------
 Reporter:  arst                             |       Owner:  vadz   
     Type:  defect                           |      Status:  new    
 Priority:  normal                           |   Milestone:  2.9.0  
Component:  base                             |     Version:  2.9-svn
 Keywords:  wxEvtHandler Disconnect Connect  |   Blockedby:         
    Patch:  0                                |    Blocking:         
---------------------------------------------+------------------------------
 This happened in my app on closing a popup editor (which does a bit of
 Connect/Disconnect). The crash happens inside
 wxEvtHandler::SearchDynamicEventTable.

 Looking at the source it's fairly clear what goes wrong:

 {{{
         // get next node before (maybe) calling the event handler as it
 could
         // call Disconnect() invalidating the current node
         node = node->GetNext();
 }}}

 Well, also the next node may be disconnected by the event handler.

 Some variant of weak ref mechanism is needed when traversing a list that
 can be modified while traversing it. Maybe one could delay removing the
 handlers from the list until it's been traversed (g_pendingDisconnects).


 (My event handler did Skip() on the event. By detecting when I was doing
 Disconnect() and then _not_ do Skip() I was able to work around it. But
 that doesn't feel very solid).

 Regards
 // ATS.


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Ticket URL: <http://trac.wxwidgets.org/ticket/9708>