[pywin32-bugs] [ pywin32-Bugs-2924128 ] Crash in dispatchServiceCtrl() for service with power event

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Bugs item #2924128, was opened at 2009-12-31 22:25
Message generated for change (Comment added) made by mhammond
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Category: None
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Private: No
Submitted By: rolyapples (rolyapples)
Assigned to: Mark Hammond (mhammond)
Summary: Crash in dispatchServiceCtrl() for service with power event

Initial Comment:
If you create a service that accepts power events (by overriding GetAcceptedControls), the service will crash in dispatchServiceCtrl() when any power event other than PBT_POWERSETTINGCHANGE occurs.

The problem is that the code assumes eventData for a SERVICE_CONTROL_POWEREVENT is always a pointer to a POWERBROADCAST_SETTING structure, however that is only the case when dwEventType is PBT_POWERSETTINGCHANGE. For other event types (e.g. PBT_APMSUSPEND), the eventData is null.

To reproduce:

1. From your python install directory run "python Lib\site-packages\win32\Demos\service\serviceEvents.py install"
2. Run "python Lib\site-packages\win32\Demos\service\serviceEvents.py start"
3. Put your machine to sleep
4. Wake your machine
5. Check the windows application event log - see that there's an error for the service & that the service is no longer running

Changing this in dispatchServiceCtrl() in PythonService.cpp:

case SERVICE_CONTROL_POWEREVENT: {                                                           
	POWERBROADCAST_SETTING *pbs = (POWERBROADCAST_SETTING *)eventData;                   
	sub = Py_BuildValue("NN",                                                            
			    PyWinObject_FromIID(pbs->PowerSetting),                          
			    PyString_FromStringAndSize((char *)pbs->Data, pbs->DataLength)); 
	break;    

To the following is working for me:

case SERVICE_CONTROL_POWEREVENT: {                                                                   
	if (dwEventType == PBT_POWERSETTINGCHANGE) {                                                 
		POWERBROADCAST_SETTING *pbs = (POWERBROADCAST_SETTING *)eventData;                   
		sub = Py_BuildValue("NN",                                                            
			    PyWinObject_FromIID(pbs->PowerSetting),                                  
			    PyString_FromStringAndSize((char *)pbs->Data, pbs->DataLength));         
	}                                                                                            
	else {                                                                                       
		sub = Py_None;                                                                       
		Py_INCREF(sub);                                                                      
	}                                                                                            
	break;                                                                                       


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>Comment By: Mark Hammond (mhammond)
Date: 2010-08-30 14:26

Message:
thanks
Checking in PythonService.cpp;
new revision: 1.28; previous revision: 1.27

----------------------------------------------------------------------

Comment By: Mark Hammond (mhammond)
Date: 2010-01-02 13:10

Message:
looks good, thanks!

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=551954&aid=2924128&group_id=78018