Bug 49153

Cannot reproduce this. Which steps did you leave out (obviously at least the 
one creating a second session) to make it reproducible? :-) 

Subject: Re:  deattach/attach session -> key input is doubled

On Tue, Oct 15, 2002 ve 05:46:48PM -0000, Stephan Binner wrote:
> Cannot reproduce this. Which steps did you leave out (obviously at least the 
> one creating a second session) to make it reproducible? :-)

oops, okey, start konsole, create two sessions, deattach/attach one of them
-> double-chars :) CVS(14.10.2002)

Ok, I can reproduce this - but only with current qt-copy, Qt 3.0.6 works fine. 
Can you confirm that you use qt-copy (and why doesn't ask the bug system 
this)? 

Subject: Re:  deattach/attach session -> key input is doubled

Dne st 16. 

http://lists.kde.org/?l=konsole-devel&m=103512276507858&w=2 has a work-around   
patch for use with qt-copy, thanks. :-) But better try to find this subtle bug 
as long there is time left before it bugs us again somewhere else.   
Tronical, do you succeed in creating a simple test case for TrollTech? :-)   

Created attachment 225 [details]
patch to fix invalid reads when attaching session

While debugging (it looks indeed like a Qt bug) I noticed that when attaching the KonsoleChild     
destructor deletes the TEWidget object before emitting the doneChild signal. the signal emission   
leads to attachSession and somewhen it ends up in TEmulation::changeGUI . At this point the gui  
member variable is a dangling pointer because the TEWidget is already dead. See attached patch for  
a fix for the invalid reads caused by that. (nope, that doesn't fix this bug, it's just a side-effect :)  

Created attachment 236 [details]
fix slot declaration

This patch fixes the slot declaration to make the connection in the base class
constructor use the same slot when disconnecting later (when the TEmuVt102
class) is ininitialized.

OK, turned out not to be a real Qt bug. TEmulation declares the onKeyPress slot. TEmuVt102's   
declares the slot again, so the slot is listed twice, once in TEmulation's QMetaObject and once in    
TEmuVt102's one. But as the TEmulation constructor calls connectGUI at this time only the   
onKeyPressed slot of TEmulation is avaiable, because the vtbl of the object is not adjusted to   
TEmuVt102 yet, so the metaObject method still returns TEmulations' QMetaObject. As a result in   
the sender object the member index of TEmulation's onKeyPressed signal is stored (in the   
connection list) .  
  
At run-time it doesn't make a difference as the slot method was marked virtual.  
  
But when disconnecting metaObject() returns TEmuVt102's metaobject and there disconnect  
immediately finds the onKeyPressed slot and tries to disconnect that one. It fails however as the  
member index is different to the one in the base class.  
  
The fact that it worked with Qt 3.0.x I would call a fortune or something like relying on undefined  
behaviour :)  
  
Attachment 2 [details] fixes the bug. 
 
Konsole developers, please approve both patches :) 

Ouch, thanks for your efforts. Please commit the patches. 

Subject: kdebase/konsole/konsole

CVS commit by hausmann: 

- fixed an invalid read when attaching a detached session
- fixed keyPress signal/slot connection when detaching and re-attaching
  a session
  See #49153 for details about both patches. Approved by Beineri
CCMAIL: 49153-done@bugs.kde.org

  M  +7 -5     TEmuVt102.cpp   1.95
  M  +1 -1     TEmuVt102.h   1.33
  M  +23 -21   TEmulation.cpp   1.45
  M  +2 -1     TEmulation.h   1.27