328804 - Create second instance of EventQueue sevice, no error

Status: RESOLVED INVALID

(Core :: XPCOM, defect)

Description

[Jon Smirl]

I accidentally created a second instance of the EventQueue sevice and received no error (rv == 0). Shouldn't this cause an error? It resulted in a messed up event pump and it was hard to debug. The symptom was that proxy objects failed to work.

Wrong:
   rv = compMan->CreateInstanceByContractID(NS_EVENTQUEUESERVICE_CONTRACTID,
                                           nsnull,
                                           NS_GET_IID(nsIEventQueueService),
                                           getter_AddRefs(eqs));    
I meant to do this:
    rv = servMan->GetServiceByContractID(NS_EVENTQUEUESERVICE_CONTRACTID,
                                             NS_GET_IID(nsIEventQueueService),
                                             getter_AddRefs(eqs));

Comment 1

[Darin Fisher]

Yes, it is a bug.  However, note that my patch for bug 326273 eliminates nsEventQueueService.

Comment 2

[Benjamin Smedberg]

Well, it shouldn't be considered a bug in the EQS: this code is buggy since you should be using getservice, not createinstance. EQS doesn't keep a static "gInstance" or anything like that.

Comment 3

[Jon Smirl]

There is clearly a bug here, I passed in some invalid parameters to an API and the API misbehaved instead of returning an error. This should be resolved as WONTFIX instead of INVALID.

I mistakenly translated this from some existing Javascript. Can an arbitrary web page trigger this? If you trigger it the browser stops working.

Comment 4

[Darin Fisher]

> I mistakenly translated this from some existing Javascript. Can an arbitrary
> web page trigger this? If you trigger it the browser stops working.

No, the API you are using requires permissions that a website does not have.