Wrong process ID if target executable doesn't exist

[alex6dj]

Version

3.3.3

Details

When I try tu run an executable using this library, and the executable dont exist, it reports process id as zero. The problem is that the zero process id is valid and it represent the System Idle Process, it is not really a process but can cause a Win32Exception if you try to change his id process priority.

Steps to reproduce

This is part of my code

• Install library

• Execute a command but with a wrong executable path (Windows).

string ffmpegPath = "...";

var cmd = Cli.Wrap(ffmpegPath)
                .WithValidation(CommandResultValidation.None)
                .WithArguments(arguments);

var observable = cmd.Observe(cancellationToken).Publish();

var changePriority = observable.Select(x => x as StartedCommandEvent)
                .Where(x => x != null)
                .Take(1)
                .Select(x => x.ProcessId)
                //.Where(x => x > 0)   // This filters the process id only accepting values above zero
                .Subscribe(SetPriorityByProcessId); // Proccess id == 0  then Win32Exception

observable.Connect()

void SetPriorityByProcessId(int processId)
{
    var process = Process.GetProcessById(processId);
    process.PriorityClass = ProcessPriorityClass.BelowNormal;
}

[alex6dj]

I think we should avoid the use of process id zero or at least inform the behaviour.

[Tyrrrz]

If the target file path doesn't exist, it should throw an exception before it even produces StartedCommandEvent. Are you sure that's what's happening?

[alex6dj]

Yes, I am sure this is what is happening in my case. I am going to try to create a small project to replicate the error.

[alex6dj]

Project done. CliWrapWrongIdExample

[alex6dj]

This use latest version (3.4) and same behaviour.

[Tyrrrz]

Thanks I'll take a look

[Tyrrrz]

Thank you for the report, fixed. It should now throw an exception as expected.