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POProblem reading port information
 

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  1. POProblem reading port information
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    <p>I have a problem retrieving the information of printer ports. I already use <a href="http://msdn.microsoft.com/en-ca/library/ff562761%28VS.85%29.aspx" rel="nofollow">XcvData</a> function to add, configure and delete ports, but I can not get the following to run as I expect it to:</p> <pre><code>public PrinterNativeMethods.PORT_DATA_1 GetPortData1FromPort(string serverName, string portName) { IntPtr printerHandle; PrinterNativeMethods.PRINTER_DEFAULTS defaults = new PrinterNativeMethods.PRINTER_DEFAULTS { DesiredAccess = PrinterNativeMethods.PrinterAccess.ServerAdmin }; string connection = string.Format(@"{0},XcvPort {1}", serverName, portName); PrinterNativeMethods.OpenPrinter(connection, out printerHandle, ref defaults); PrinterNativeMethods.CONFIG_INFO_DATA_1 configData = new PrinterNativeMethods.CONFIG_INFO_DATA_1 { dwVersion = 1, }; uint size = (uint)Marshal.SizeOf(configData); IntPtr pointer = Marshal.AllocHGlobal((int)size); Marshal.StructureToPtr(configData, pointer, true); PrinterNativeMethods.PORT_DATA_1 portData = new PrinterNativeMethods.PORT_DATA_1(); uint portDataSize = (uint)Marshal.SizeOf(portData); IntPtr portDataHandle = Marshal.AllocHGlobal((int)portDataSize); try { uint outputNeeded; uint status; var retVal = PrinterNativeMethods.XcvData(printerHandle, "GetConfigInfo", pointer, size, out portDataHandle, portDataSize, out outputNeeded, out status); //portDataHandle now points to a different location!? Unmarshalling will fail: portData = (PrinterNativeMethods.PORT_DATA_1)Marshal.PtrToStructure(portDataHandle, typeof(PrinterNativeMethods.PORT_DATA_1)); } finally { PrinterNativeMethods.ClosePrinter(printerHandle); Marshal.FreeHGlobal(pointer); Marshal.FreeHGlobal(portDataHandle); } return portData; } </code></pre> <p>from PrinterNativeMethods:</p> <pre><code> [DllImport("winspool.drv", SetLastError = true, CharSet = CharSet.Unicode)] internal static extern int XcvData( IntPtr handle, string dataName, IntPtr inputData, uint inputDataSize, out IntPtr outputData, uint outputDataSize, out uint outputNeededSize, out uint status); [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct PORT_DATA_1 { [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)] public string sztPortName; public uint dwVersion; public uint dwProtocol; public uint cbSize; public uint dwReserved; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 49)] public string sztHostAddress; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 33h)] public string sztSNMPCommunity; public uint dwDoubleSpool; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 33)] public string sztQueue; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)] public string sztIPAddress; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 540)] public byte[] Reserved; public uint dwPortNumber; public uint dwSNMPEnabled; public uint dwSNMPDevIndex; } </code></pre> <p>Additional comment: I cannot use WMI or prnadmin.dll as an alternative.</p>
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    1. USSomeCallMeTim
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      1. VTUpMod
    1. COPlease define "run as I expect". Are any exceptions thrown? What actually happens? Where exactly is the code not doing what you expect?
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      1. POProblem reading port information
      1. USPolyfun
    2. COI would expect it to work ;-), I get an AccessViolationException on the call below var retVal = PrinterNativeMethods.XcvData(...). I noticed that the IntPtr portDataHandle has a different value after the call to XcvData.
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      1. POProblem reading port information
      1. USSomeCallMeTim
 

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