Parameter "ReturnLength" always "0" when NtQuerySystemInformation is called,...

Kerem Gümrükcü

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Aug 23, 2008, 4:11:39 PM8/23/08

to

Hi,

the topic says all. I use this code from C# to call the
NtQuerySystemInformation.
When i call NtQuerySystemInformation the first time with zero buffer length
to
get the buffer size needed for the information i get a
STATUS_INFO_LENGTH_MISMATCH
which is -1073741820 in number, this is ok, but why does the function not
store the required
buffer size in "ReturnLength"? Its always zero,...why? Is something wrong
with my declaration:

[DllImport("ntdll.dll",
EntryPoint = "NtQuerySystemInformation",
SetLastError = true,
CharSet = CharSet.Unicode,
ExactSpelling = true,
CallingConvention = CallingConvention.Winapi)]
public static extern int NtQuerySystemInformation(
SYSTEM_INFORMATION_CLASS SystemInformationClass,
IntPtr SystemInformation,
uint SystemInformationLength,
out uint ReturnLength);

uint l = 0;
IntPtr ptrBuffer = Marshal.AllocHGlobal(10000000); //just some "buffer"
space, not used
int err = DRWin32APIClass.NtQuerySystemInformation(
DRWin32APIClass.SYSTEM_INFORMATION_CLASS.SystemBasicInformation,
ptrBuffer,
10000000,
out l);

MessageBox.Show(DRWin32APIClass.NtStatusToWin32Exception(err).Message + "\n"
+ err.ToString() + "\n" + l.ToString());

Marshal.FreeHGlobal(ptrBuffer);

The "ReturnLength" is always zero (0),...very strange. I am doing something
wrong here,...

I know that i can use for this class the Win32 API GetSystemInfo(...), but
the
call fails on any class, no matter if i want some Handles/Objects, etc
Information,...

Regards

Kerem

--
-----------------------
Beste Grüsse / Best regards / Votre bien devoue
Kerem Gümrükcü
Latest Project: http://www.codeplex.com/restarts
Latest Open-Source Projects: http://entwicklung.junetz.de
-----------------------
"This reply is provided as is, without warranty express or implied."

Kerem Gümrükcü

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Aug 23, 2008, 5:06:52 PM8/23/08

to

dominique

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Aug 24, 2008, 6:29:10 AM8/24/08

to

Kerem Gümrükcü wrote:
> Hi,
>
> the topic says all. I use this code from C# to call the
> NtQuerySystemInformation.
> When i call NtQuerySystemInformation the first time with zero buffer
> length to
> get the buffer size needed for the information i get a
> STATUS_INFO_LENGTH_MISMATCH
> which is -1073741820 in number, this is ok, but why does the function
> not store the required
> buffer size in "ReturnLength"? Its always zero,...why? Is something
> wrong with my declaration:

Have you compared with others working samples ?
like http://archive.sadeveloper.net/Forums/PostAttachment.aspx?PostID=73987

Kerem Gümrükcü

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Aug 27, 2008, 1:00:16 AM8/27/08

to

Hi Dominique,

for whatever reason, i still get ZERO as NeededSize
on the OUT Parameter...i am really confused!

Using this is,...useless:

[DllImport("ntdll.dll",
EntryPoint = "NtQuerySystemInformation",
SetLastError = true,
CharSet = CharSet.Unicode,
ExactSpelling = true,
CallingConvention = CallingConvention.Winapi)]
public static extern int NtQuerySystemInformation(

[In] SYSTEM_INFORMATION_CLASS SystemInformationClass,
[In] IntPtr SystemInformation,
[In] uint SystemInformationLength,
[Out] out uint ReturnLength);

"ReturnLength" is always ZERO!

System is Windows XP SP3

Regards

Kerem

--
-----------------------
Beste Grüsse / Best regards / Votre bien devoue
Kerem Gümrükcü
Latest Project: http://www.codeplex.com/restarts
Latest Open-Source Projects: http://entwicklung.junetz.de
-----------------------
"This reply is provided as is, without warranty express or implied."

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