GSoC 2013 - Registry Merging Project

[Juan Lang]

Hi Guo,

On Tue, May 14, 2013 at 1:32 PM, Guo Jian <orzhvs at gmail.com> wrote:

> I just found that the REG_OPTION_VOLATILE of create_key in hkcr may
> have some tricks. Not surprisingly found a strange situation when
> testing on windows. See my test here please :
> http://newtestbot.winehq.org/JobDetails.pl?Key=932
> This happens as following :
> First create hkcu/software/classes/key1, then create the
> hkcr/key1/subkey with REG_OPTION_VOLATILE. RegEnumKey on hkcr  will
> give two 'key1'.
>
I tried to use RegQueryInfoKeyA to count them, also there are more
> than there should be.
> Why there are two duplicated keys? May it be a bug of windows? If it
> is, should we design our algorithm to avoid or treat it as a normal
> feature?
>

That's interesting. Windows might allow both a volatile and non-volatile
key of the same name. Since the volatile one is kept in-memory, any values
that exist in it will be discarded eventually, so any inconsistency that
arises isn't the kernel's problem. That'd be my guess, at any rate: even
though such a behavior has the potential to confuse application developers,
since it's not the kernel's problem, it's probably an overlooked quirk.

As far as what to do with it: this is one of those nuanced, i.e. hard to
decide, things with our tests.

In general, we assume that Windows's behavior is the correct behavior,
unless we have strong reason to assume otherwise. We've encountered many
times that even what appear to be bugs end up being relied upon by
application developers.

In this case, though, I think you might have stumbled across something
that's relatively rare, and unless there's an application that depends on
this behavior, it might be worth ignoring for now.

Hope that helps.
--Juan
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