Printing a PDF from a Windows Service using GhostScript - How to diagnose permission issue

Question

I have a service written in C#. Running the following code:

public static bool PrintPDF(string ghostScriptPath, int numberOfCopies, string printerName, string pdfFileName)
{
    ProcessStartInfo startInfo = new ProcessStartInfo();
    startInfo.Arguments = $@"-dPrinted -dNoCancel=true -dBATCH -dNOPAUSE -dNOSAFER -q -dNumCopies={numberOfCopies} -sDEVICE=mswinpr2 -sOutputFile=""\\spool\{printerName}"" ""{pdfFileName}""";

    startInfo.FileName = Path.Combine(ghostScriptPath, "gswin64c.exe");
    startInfo.UseShellExecute = false;
    startInfo.CreateNoWindow = true;
    startInfo.RedirectStandardError = true;
    startInfo.RedirectStandardOutput = true;

    Process process = Process.Start(startInfo);

    Console.WriteLine(process.StandardError.ReadToEnd() + process.StandardOutput.ReadToEnd());

    process.WaitForExit(30000);
    if (process.HasExited == false) process.Kill();


    return process.ExitCode == 0;
}

Outside of Windows Service, it's working without any problem. Inside the service, when running as Local System, GhostScript started running but timed out without any output.

After some fiddling around, I finally switched the service to run as Network Service and also set Network Service as owner of the folder from which the service exe and GhostScript exe where placed (Before I did that, I got Access Denied error) - And now the service is running fine.

My questions is - How come Network Service can work where Local System can't? I thought Local System has more privileges. And also, how can I get more info regarding the actual issue? I've found a workaround but it was simply a lucky shot in the dark. I have no idea what the real problem is.

Some more info: Running Windows 10 64 bit, and using GhostScript v9.29

Answer 1

You need to run the service under a local user account that is dedicated to it. You also need to login with that user at list one time in order the printer list to be populated!