http://www.winehq.org/pipermail/wine-patches/2007-June/040336.html
 
The third version I sent out (yes I know, I was quite sleepy) _is_ correct though.
 
And that particular call _will_ return ERROR_SUCCESS and _not_ ERROR_MORE_DATA,
see:
http://msdn2.microsoft.com/en-us/library/ms724911.aspx
Specifically, a call to RegQueryValueEx with a NULL data pointer and a valid size pointer returns
ERROR_SUCCESS if the size pointer is filled, _not_ ERROR_MORE_DATA, which is returned
if a valid data pointer is passed.
Misha

From: James Hawkins [mailto:truiken@gmail.com]
Sent: Wed 6/13/2007 1:22 AM
To: wine-devel@winehq.org
Cc: Koshelev, Misha Vladislavo
Subject: Re: msi: Do not use type value if call to RegQueryValueEx failed.

On 6/12/07, Misha Koshelev <mk144210@bcm.edu> wrote:
> This is necessary (bug not sufficient, see my comment in the bug report that I am about
> to post) to fix bug 8678.
>
> It is also clearly correct, as checking the type "returned" by RegQueryValueEx when it fails
> makes no sense.
>

     size = 0;

     res = RegQueryValueExW(env, var, NULL, &type, NULL, &size);

-    if ((res != ERROR_MORE_DATA && res != ERROR_FILE_NOT_FOUND) ||
type != REG_SZ)

+    if ((res != ERROR_MORE_DATA && res != ERROR_FILE_NOT_FOUND) ||

+        (res == ERROR_SUCCESS && type != REG_SZ))

     {

         RegCloseKey(env);

         return res;

This is wrong.  If res == ERROR_SUCCESS, then the first condition
evaluates to TRUE and we fall through to exit, but then again, res
will never be ERROR_SUCCESS after that particular call.  Either way, I
have a patch ready to send in that fixes the entire action.

--
James Hawkins