[PATCH 1/3] shlwapi: Be less strict on which type of IShellFolder can be enumerated

[Nikolay Sivov]

On 6/4/2010 22:13, Andrew Eikum wrote:
> On 06/03/2010 03:47 PM, Andrew Eikum wrote:
>> On 06/03/2010 03:12 PM, Nikolay Sivov wrote:
>>> No, this is not what I meant actually. The possible reason it was named
>>> as IUnknown_EnumObjects is the same as for the rest of similar calls.
>>> IUknown is a valid input for all of them and another _QueryInterface is
>>> performed for IID_IShellFolder is case of this function. That makes no
>>> sense to have such export as your patch makes it, but it's possible of
>>> course. I expect that is does check that IShellFolder is supported.
>>
>> Okay, I see what you're saying now. I hadn't thought of that. After some
>> quick tests, I think you're on the right path. I'll work on fixing it.
>> Thanks!
>>
>
> So, with this in mind, here are some much more extensive tests.  As is 
> explained in the comment, Windows _does_ get the ClassID of the object 
> in this call.  But, Windows crashes when a non-IShellFolder object is 
> given to this function.  Presumably it's trying to call 
> IShellFolder_EnumObjects on it.  So it must not be using the CLSID for 
> this kind of type-checking.
And if pointer doesn't support IPersist does it crash too?
>
> Trouble is, I have no idea what it is used for.  I tried testing most 
> of the CLSIDs in shlguid.h with different combinations of flags, none 
> of which had any effect.  It must just be looking out for a small 
> number of specific CLSIDs.  One possible guess is that it tweaks the 
> flags parameter when certain CLSIDs are detected, but none of my tests 
> turned up anything interesting.
>
> Any thoughts?  Should I just send as-is?
So it doesn't care about classid returned from IPersist. I think it's 
enough now to add tests for not-called QI for IShellFolder and a test 
for a bunch of known CLSIDs for folders. After that (if you dummy CLSID 
is allowed too) probably it's ok to remove all checks.
>
> Andrew