We have some print server software written in C# (which P/Invokes functions from winspool.drv). Some of the "printers" are actually virtual printers that print to a directory. The code to install such a printer is:
public override void AddLocalDirectoryPrinter(string printerName, string directory)
{
IntPtr hPrinter = IntPtr.Zero;
try
{
PRINTER_DEFAULTS pd;
PRINTER_INFO_2 pi2;
pd.datatype = null;
pd.pDevMode = IntPtr.Zero;
// Access = PRINTER_ALL_ACCESS
// http://msdn.microsoft.com/en-us/library/cc244650%28v=prot.10%29.aspx
pd.desiredAccess = PRINTER_ALL_ACCESS;
// Attributes = PUBLISHED | DO_COMPLETE_FIRST | SHARED
// http://msdn.microsoft.com/en-us/library/aa394363%28v=vs.85%29.aspx
pi2.attributes = 0x2208;
pi2.averagePpm = 0;
pi2.jobs = 0;
pi2.defaultPriority = 0;
pi2.comment = "Auto-Generated by [name of program]";
pi2.datatype = "RAW";
pi2.pDevMode = IntPtr.Zero;
pi2.driverName = "Generic / Text Only";
pi2.location = string.Empty;
pi2.parameters = string.Empty;
pi2.portName = directory;
pi2.printerName = printerName.ToUpperInvariant();
pi2.printProcessor = "WinPrint";
pi2.priority = 0;
pi2.pSecurityDescriptor = IntPtr.Zero;
pi2.sepFile = string.Empty;
pi2.serverName = string.Empty;
pi2.shareName = printerName.ToUpperInvariant();
pi2.startTime = 0;
pi2.status = 0;
pi2.untilTime = 0;
hPrinter = AddPrinter(null, 2, ref pi2);
if (hPrinter == IntPtr.Zero)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
}
catch (Exception ex)
{
throw new PrintingException("Failed to add printer", ex);
}
finally
{
if (hPrinter != IntPtr.Zero)
{
ClosePrinter(hPrinter);
}
}
}
On 32-bit Windows XP, the above code runs without error. But on 64-bit Windows 7, the call to AddPrinter fails with Windows error 1796 ("The specified port is unknown").
Why does it work on one version of Windows but not another?
