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From: John Bond on 12 Mar 2010 16:57
Problem with ZwEnumerateKey

Code fragment is run in a KMDF 1.7 driver under Windows 7


//the size of this union works for SmartWORKS subkeys (Bus#Slot#) of
Parameters\Devices\MtxBrd
union {
KEY_BASIC_INFORMATION Basic;
KEY_NODE_INFORMATION Node;
KEY_FULL_INFORMATION Full;
KEY_NAME_INFORMATION Name;
WCHAR wcRaw[256]; //provides extra space for Name & Class members
(overkill?)
} SubKeyInfo;

SwrxRegistry *Found = NULL;
HANDLE hKey = WdfRegistryWdmGetHandle(Key);
findIndex = 0;
ULONG RequiredLength;

//JBHERE junk test code...
NTSTATUS junkStatus = ZwQueryKey(hKey, KeyNameInformation,
&SubKeyInfo, sizeof(SubKeyInfo), &RequiredLength);

UNICODE_STRING us;
RtlInitUnicodeString(&us, SubKeyInfo.Name.Name);

TraceEvents(etInfo, DBG_REGISTRY, "ZwQueryKey(0x%p) name=%wZ, %!STATUS!",
hKey, &us, junkStatus);

junkStatus = ZwQueryKey(hKey, KeyFullInformation,
&SubKeyInfo, sizeof(SubKeyInfo), &RequiredLength);

TraceEvents(etInfo, DBG_REGISTRY, "ZwQueryKey(0x%p) subkeys=%d
%!STATUS!",
hKey, SubKeyInfo.Full.SubKeys, junkStatus);

findStatus = ZwEnumerateKey(hKey, findIndex++, KeyNameInformation,
&SubKeyInfo, sizeof(SubKeyInfo), &RequiredLength);

TraceEvents(etError, DBG_REGISTRY, "ZwEnumerateKey handle 0x%p length %d
index %d reqsize %d -- %!STATUS!",
hKey, SubKeyInfo.Name.NameLength, findIndex-1, RequiredLength,
findStatus);


The above code reports the correct name of the key and that there are two
subkeys... fine, but ZwEnumerateKey returns
STATUS_INVALID_PARAMETER...

I am perplexed, any ideas?

John Bond
From: John Bond on 16 Mar 2010 10:47
Over the last two days, I found out the hard way, that even though
“KeyNameInformation” is a valid KEY_INFORMATION_CLASS enum...
It is NOT a valid 3rd parameter for ZwEnumerateKey… but the documentation
only gives the slightest of hints to this problem. The function returns
STATUS_INVALID_PARAMETER, which the doc says is caused by a 3rd parameter
which is not of a certain type… but alas, it is a valid KEY_INFORMATION_CLASS
enum, but just not valid for this function… (sigh)
Could you add a comment saying that KeyNameInformation should not be used,
but rather KeyNodeInformation… that is the best way to get the name of a
SubKey.
This could save someone else two days of wasted time writing a KMDF driver.

From: Doron Holan [MSFT] on 16 Mar 2010 18:50
did you send feedback on the webpage for ZwEnumerateKey with this comment?
that feedback goes prety quickly to the doc writers who authored the page

d

--

This posting is provided "AS IS" with no warranties, and confers no rights.


"John Bond" <johnbond(a)newsgroup.nospam> wrote in message
news:9DDE589C-E99B-4A80-A2BD-322C7AE834B4(a)microsoft.com...
> Over the last two days, I found out the hard way, that even though
> “KeyNameInformation” is a valid KEY_INFORMATION_CLASS enum...
> It is NOT a valid 3rd parameter for ZwEnumerateKey… but the documentation
> only gives the slightest of hints to this problem. The function returns
> STATUS_INVALID_PARAMETER, which the doc says is caused by a 3rd parameter
> which is not of a certain type… but alas, it is a valid
> KEY_INFORMATION_CLASS
> enum, but just not valid for this function… (sigh)
> Could you add a comment saying that KeyNameInformation should not be used,
> but rather KeyNodeInformation… that is the best way to get the name of a
> SubKey.
> This could save someone else two days of wasted time writing a KMDF
> driver.
>
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