[Live-devel] Segmentation fault in DelayQueue::removeEntry(DelayQueueEntry*)

[Francisco Feijoo]

Ross, thanks for the quick answer.

We are connecting to one camera which needs a keep-alive command continuously. Apart from the doEventLoop() we call this function periodically (60s):

void RtspConnection::timeout()
{
	if ( client && session && this->getParameterSupported )
	{
		char * psz_bye = NULL;
		((RTSPClient*)client)->getMediaSessionParameter( *session, NULL, psz_bye );
	}
}
getParameterSupported comes from: 
char * options = ((RTSPClient*)client)->sendOptionsCmd( this->host );
		
if ( strstr(options, "GET_PARAMETER") != NULL )
{
	this->getParameterSupported = true;
}

Is this a wrong way to maintain the connection to the camera? Could this be the cause of the crash?

Thanks in advance.
-- 
Francisco Feijoo
Software Engineer
J2K Video Limited

T: +44 020 8133 9388
E: francisco at j2kvideo.com
W: www.j2kvideo.com

El 04/11/2011, a las 15:10, Ross Finlayson escribió:

>> Looking at the code here http://www.live555.com/liveMedia/doxygen/html/DelayQueue_8cpp-source.html I see this:
>> 
>> 00153 void DelayQueue::removeEntry(DelayQueueEntry* entry) {
>> 00154   if (entry == NULL || entry->fNext == NULL) return;
>> 00155   
>> 00156   entry->fNext->fDeltaTimeRemaining += entry->fDeltaTimeRemaining;
>> 00157   entry->fPrev->fNext = entry->fNext;
>> 00158   entry->fNext->fPrev = entry->fPrev;
>> 00159   entry->fNext = entry->fPrev = NULL;
>> 00160   // in case we should try to remove it again
>> 00161 }
>> 
>> I think the first if could produce a wrong memory access if entry is NULL. Is that correct?
> 
> No, because the statement at line 154 quite clearly tests for "entry == NULL", and returns if it is.
> 
> The "DelayQueue" code is very widely used and has been tested for a long time, so I don't understand why you would be seeing an error there.  (I hope you're not doing something stupid like trying to use multiple threads?)
> 
> 
> Ross Finlayson
> Live Networks, Inc.
> http://www.live555.com/
> 
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> live-devel at lists.live555.com
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