.NET : How to call CreateProcessAsUser() with STARTUPINFOEX from C#

Question

Most sample code on the web for calling CreateProcessAsUser() has a similar PInvoke signature to the following:

    public static extern bool CreateProcessAsUser(IntPtr hToken,
        string lpApplicationName,
        string lpCommandLine,
        ref SECURITY_ATTRIBUTES lpProcessAttributes,
        ref SECURITY_ATTRIBUTES lpThreadAttributes,
        bool bInheritHandles,
        int creationFlags,
        IntPtr environment,
        string currentDirectory,
        ref STARTUPINFO startupInfo,
        out PROCESS_INFORMATION processInfo);

The problem is, I want to pass STARTUPINFOEX instead, which is allowed in Vista/W7. If I was writing C/C++ then I could just cast it.

How should I deal with this in C#? STARTUPINFOEX looks like this:

    [StructLayout(LayoutKind.Sequential)]
    public struct STARTUPINFOEX
    {
        public STARTUPINFO StartupInfo;
        public IntPtr lpAttributeList;
    };

Should I be passing an IntPtr to the structure instead? If I change the Pinvoke signature and do something like this...

   IntPtr pStartupInfoEx = Marshal.AllocHGlobal(Marshal.SizeOf(startupInfoEx));
   Marshal.StructureToPtr(startupInfoEx, pStartupInfoEx, true);

.. I crash my shell when I execute the CreateProcessAsUser() :(

Any ideas gratefully received. Thank you.

score 0 · Accepted Answer · answered Sep 16 '09 at 13:18

0

I think you should just pass it like the STARTUPINFO, I mean with the ref keyword. The marshaling of the structure is done the same way it is done for the STARTUPINFO.

answered Sep 16 '09 at 13:18

cedrou

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So do you mean declare CreateProcessAsUser with ref STARTUPINFOEX instead of ref STARTUPINFO? – mrbouffant Sep 16 '09 at 13:24
OK, that doesn't crash BUT the call doesn't work - returning error 183. Even if I forget about setting the lpAttributeList and using it essentially as STARTUPINFO (i.e. lpAttributeList) the call returns 183. Argh. – mrbouffant Sep 17 '09 at 15:00
1

FIXED it at last - when I declare STARTUPINFOEX I was failing to set the cb member of the embedded STARTUPINO to the value returned by Marshal.SizeOf(). All works now and I can reparent my processes under W7 from managed code :) Thanks for the hint about ref STARTUPINFOEX - that is exactly right. – mrbouffant Sep 18 '09 at 12:44

.NET : How to call CreateProcessAsUser() with STARTUPINFOEX from C#

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