Hi,

I'm trying to get the objectSID from the active directory objects selected 
in the directory object picker dialog. But IDataObject.GetData() returns 
always 0x80004001 (E_NOTIMPL) when I supply the attribute 'objectSID' in 
DSOP_INIT_INFO. Without this attribute (cAttributesToFetch=0), the code 
works. I also have a sample using the same flags and settings written in 
Delphi that works fine. So I suppose the marshalling is incorrect, but I 
don't know where. Below is an excerpt of my code.

Thanks very much for any help.
Beat


[ComImport, Guid("17D6CCD8-3B7B-11D2-B9E0-00C04FD8DBF7")]
public class DSObjectPicker {}

[ComImport, Guid("0C87E64E-3B7A-11D2-B9E0-00C04FD8DBF7"),
InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IDsObjectPicker
{
    void Initialize(ref DSOP_INIT_INFO pInitInfo);
    void InvokeDialog(IntPtr HWND, out IDataObject lpDataObject);
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct DSOP_INIT_INFO
{
    public uint cbSize;
    [MarshalAs(UnmanagedType.LPWStr)]
    public string pwzTargetComputer;
    public uint cDsScopeInfos;
    public IntPtr aDsScopeInfos;
    public uint flOptions;
    public uint cAttributesToFetch;
    public IntPtr apwzAttributeNames;
}

// other structs, enums, ... (skipped)

public class ObjectPickerWrapper
{
    public ADObject[] ShowObjectPicker(IntPtr parentHandle)
    {
        DSObjectPicker picker = new DSObjectPicker();
        IDsObjectPicker ipicker = (IDsObjectPicker)picker;

        DSOP_SCOPE_INIT_INFO[] scopeInitInfo = new DSOP_SCOPE_INIT_INFO[1];

        scopeInitInfo[0].cbSize = 
(uint)Marshal.SizeOf(typeof(DSOP_SCOPE_INIT_INFO));
        scopeInitInfo[0].flType = 
DSOP_SCOPE_TYPE_FLAGS.DSOP_SCOPE_TYPE_GLOBAL_CATALOG;
        scopeInitInfo[0].FilterFlags.Uplevel.flBothModes =
            DSOP_FILTER_FLAGS_FLAGS.DSOP_FILTER_USERS; // ...

        scopeInitInfo[0].FilterFlags.flDownlevel =
            DSOP_DOWNLEVEL_FLAGS.DSOP_DOWNLEVEL_FILTER_USERS; // ...

        scopeInitInfo[0].pwzADsPath = null;
        scopeInitInfo[0].pwzDcName = null;
        scopeInitInfo[0].hr = 0;

        IntPtr refScopeInitInfo = Marshal.AllocHGlobal(
            Marshal.SizeOf(typeof(DSOP_SCOPE_INIT_INFO)) * 
scopeInitInfo.Length);
        Marshal.StructureToPtr(scopeInitInfo[0], refScopeInitInfo, true);

        DSOP_INIT_INFO initInfo = new DSOP_INIT_INFO();
        initInfo.pwzTargetComputer = null;
        initInfo.flOptions = DSOP_INIT_INFO_FLAGS.DSOP_FLAG_MULTISELECT;
        initInfo.cDsScopeInfos = 1;
        initInfo.aDsScopeInfos = refScopeInitInfo;

        string attrName = "objectSID";
        IntPtr refAttrName = Marshal.StringToHGlobalUni(attrName);
        initInfo.cAttributesToFetch = 1;
        initInfo.apwzAttributeNames = refAttrName;  // <== marshalling / 
memory layout ok??

        ipicker.Initialize(ref initInfo);

        // show the dialog
        IDataObject dataObj = null;
        ipicker.InvokeDialog(parentHandle, out dataObj);

        FORMATETC fmt = new FORMATETC();
        fmt.cfFormat = 
(short)System.Windows.Forms.DataFormats.GetFormat("CFSTR_DSOP_DS_SELECTION_LIST").Id; 
// -15497 (unsigned 50039)
        fmt.ptd = IntPtr.Zero;
        fmt.dwAspect = DVASPECT.DVASPECT_CONTENT;
        fmt.lindex = -1;
        fmt.tymed = TYMED.TYMED_HGLOBAL;

        STGMEDIUM stg = new STGMEDIUM();

        // int res = dataObj.QueryGetData(ref fmt);   // <== HRESULT is 
always 0x80004001 (E_NOTIMPL)

        dataObj.GetData(ref fmt, out stg);  // throws 'not implemented' 
Exception from HRESULT 0x80004001 (E_NOTIMPL)

        // ... processing stg... (skipped)

        return new ADObject[0];
    }
}

.... the marshalling of the string array was incorrect. It can be done like 
this:



public sealed class packLPArray

{

    private IntPtr taskAlloc;

    private readonly int _length;

    private IntPtr[] _strings;



    public packLPArray(string[] theArray)

    {

        int sizeIntPtr = IntPtr.Size;

        int neededSize = 0;

        if (theArray != null)

        {

            this._length = theArray.Length;

            this._strings = new IntPtr[this._length];

            neededSize = this._length * sizeIntPtr;

            this.taskAlloc = Marshal.AllocCoTaskMem(neededSize);

            for (int cx = this._length - 1; cx >= 0; cx--)

            {

                this._strings[cx] = 
Marshal.StringToCoTaskMemUni(theArray[cx]);

                Marshal.WriteIntPtr(this.taskAlloc, cx * sizeIntPtr, 
this._strings[cx]);

            }

        }

    }



    public IntPtr arrayPtr

    {

        get { return this.taskAlloc; }

    }



    ~packLPArray()

    {

        if (taskAlloc != IntPtr.Zero)

        {

            Marshal.FreeCoTaskMem(this.taskAlloc);

            int cx = this._length;

            while(cx-- != 0)

                Marshal.FreeCoTaskMem(this._strings[cx]);

        }

    }

}



....

packLPArray packit = new packLPArray( new string[] 
{"SamAccountName","cn","Adspath","objectsid"});

initInfo.cAttributesToFetch = 4;

initInfo.apwzAttributeNames = packit.arrayPtr;

....



Beat