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I'm having a problem calling Winspool.drv "OpenPrinter" when I run my program in standard user acccount. But when I ran my program in Administrator account. It can properly execute API call.

I am trying to call OpenPrinter using this API

[DllImport("WinSpool.drv", SetLastError = true)]
static extern unsafe bool OpenPrinter (string pPrinterName, int* phPrinter, void* pDefault);
and implementing it using this code
static unsafe int CSOpenPrinter(string printerName)
    bool bResult;
    int hPrinter;
    PRINTER_DEFAULTS pd = new PRINTER_DEFAULTS();
    //int rawsize = Marshal.SizeOf(pd);
    //IntPtr pdPtr = Marshal.AllocHGlobal(rawsize);
    //pd.pDatatype = null;
    //pd.pDevMode = null;
    pd.DesiredAccess = PRINTER_ALL_ACCESS;
    bResult = OpenPrinter(printerName, &hPrinter, &pd);
    System.Diagnostics.Debug.WriteLine("bResult: " + bResult);
    if (!bResult)
        throw new ApplicationException("Cannot open printer '" +
                                        printerName + "' " +
                                        Marshal.GetLastWin32Error());
    return hPrinter;
Ok again, that code works perfectly when I try to make my program "Run As Administrator". How do I make my application run as a Administrator without right clicking on the application and selecting "Run As Administrator"?
I believe this is a UAC problem, but can you give me an Idea how to solve this? Is adding app.manifest will help? Can you give me an exampple?
Best to all
                Do you actually need PRINTER_ALL_ACCESS?  If you just want to print use PRINTER_ACCESS_USE.
– arx
                May 30, 2012 at 8:26
                I am disabling the printer as my client wants it. I am not sure why PRINTER_ACCESS_USE does not work. This the right value for PRINTER_ACCESS_USE right? PRINTER_ACCESS_USE = 0x00008 - it does not work
– Jayson Ragasa
                May 30, 2012 at 12:04
                The value is correct.  If you're disabling the printer you probably do need PRINTER_ALL_ACCESS and you will need to add a manifest: msdn.microsoft.com/en-us/library/bb756929.aspx
– arx
                May 30, 2012 at 12:41
What are you trying to do with the printer? Your code is asking for full access and so requires admin access.
If you just want to use the printer, request PRINTER_ACCESS_USE access instead.
If it is actually an admin process, then add an appropriate manifest to the executable to tell windows that it needs admin access.
                I am disabling the printer as my client wants it. I am not sure why PRINTER_ACCESS_USE does not work. This the right value for PRINTER_ACCESS_USE right? PRINTER_ACCESS_USE = 0x00008 - it does not work
– Jayson Ragasa
                May 30, 2012 at 12:02
                @JaysonRagasa: You can't change printer settings with PRINTER_ACCESS_USE.  You need PRINTER_ALL_ACCESS and a manifest for your EXE telling Windows it needs elevated privileges, as Deanna said.
– Carey Gregory
                May 30, 2012 at 16:55
        
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