Unmarshalling LsaEnumerateAccountRights() list of privileges

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Seng - 22 Nov 2004 02:39 GMT

Having trouble unmarshalling the list of rights returned by
LsaEnumerateAccountRights()

Declared it as...

[DllImport("advapi32.dll", SetLastError=true, PreserveSig=true)]
private static extern long LsaEnumerateAccountRights(
        IntPtr PolicyHandle,
            IntPtr AccountSid,
            out LSA_UNICODE_STRING[] UserRights,
            out long CountOfRights);

Called it...(after opening policy and obtaining SID)...

LSA_UNICODE_STRING[] userRights = null
long countOfRights = 0;

long res = LsaEnumerateAccountRights(policyHandle,sid,
out userRights,
out countOfRights);

string heldPrivName = Marshal.PtrToStringUni(userRights[0].Buffer);
string heldPrivName1 = Marshal.PtrToStringUni(userRights[1].Buffer);

It seems to work (in as much as 'CountOfRights' contains the correct count).
However, the userRights array that is returned only has 1 item in it -- not
2?

Can you please explain why there is a mismatch between the returned count
and the number of elements in the userRights array?

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Seng - 23 Nov 2004 18:31 GMT

Turns out I was ascribing more intelligence to the mapping of types by
Interop than I should have. Needed to think more like a "C" programmer.

First my declaration was wrong, here it is corrected...

[DllImport("advapi32.dll", SetLastError=true, PreserveSig=true)]
private static extern long LsaEnumerateAccountRights(
        IntPtr PolicyHandle,
        IntPtr AccountSid,
        out IntPtr UserRightsPtr,
        out long CountOfRights);

Then, need to map the struct onto the elements of the UserRights array one
at a time...
// UserRightsPtr was returned by LsaEnumerateAccountRights
Int32 ptr = userRightsPtr.ToInt32();
LSA_UNICODE_STRING userRight;
bool hasPriv=false;

for(int i=0; i<countOfRights; i++)
{
// Here, 'ptr' is the pointer to the buffer returned by LSA
userRight = (LSA_UNICODE_STRING)Marshal.PtrToStructure(new
IntPtr(ptr),typeof(LSA_UNICODE_STRING));
String userRightStr = Marshal.PtrToStringAuto(userRight.Buffer);
if( userRightStr == privilegeName )
{
    hasPriv = true;
    break;
}
ptr += Marshal.SizeOf(userRight);
}

> Having trouble unmarshalling the list of rights returned by
> LsaEnumerateAccountRights()
[quoted text clipped - 26 lines]
> Can you please explain why there is a mismatch between the returned count
> and the number of elements in the userRights array?

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Unmarshalling LsaEnumerateAccountRights() list of privileges

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