TAsyncProcess and Powershell

[HomeBoy38]

Hello,

I have an issue with my code and I cannot figure out what is the issue, certainly something I do not do correctly...

I have a (visual component) TAsyncProcess called PZ with [poNoConsole, poStderrToOutPut, poUsePipes].
The TAsyncProcess has 'OnReadData' event.

Code: Pascal  [Select][+][-]

1. var
2.  s : String;
3.  SLO: TStringList;
4.  
5. begin
6. PZ.Executable := 'C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe';
7. PZ.Tag := 1; // Process is running
8. SLO.Clear;
9. s := 'Enter-PSSession ' + CompName + LineEnding; // CompName is the computer name and LineEnding is CRLF
10. PZ.Input.Write(s[1], Length(s));
11. while PZ.Tag <> 0 do
12.   Application.HandleMessage;
13. ...
14.  s := 'Invoke-Command {Get-WmiObject Powershell Command}' + LineEnding;
15.  PZ.Tag := 1;
16.  PZ.Input.Write(s[1], Length(s));
17.  while PZ.Tag <> 0 do
18.   Application.HandleMessage;
19. ...
20.  

Code: Pascal  [Select][+][-]

1. procedure TMainForm.PZReadData(Sender: TObject);
2. var
3.  J: Integer;
4.  SLOtmp: TStringList;
5. begin
6.  J := 0;
7.  SLOtmp := TStringList.Create;
8.  SLOtmp.LoadFromStream(PZ.Output);
9.  
10.  if J < SLOtmp.Count then
11.  begin
12.   for J := J to SLOtmp.Count - 1 do
13.    SLO.Add(SLOtmp.Strings[J]);
14.  end;
15.  
16.  if SLOtmp.Count > 0 then
17.  begin
18.   if ((Copy(SLOtmp.Strings[SLOtmp.Count - 1], 1, 3) = 'PS ') and (Copy(SLOtmp.Strings[SLOtmp.Count - 1], Length(SLOtmp.Strings[SLOtmp.Count - 1]) - 1, 1) = '>')) or
19.      ((Copy(SLOtmp.Strings[SLOtmp.Count - 1], 1, Length(FSettings.ECompName.Text) + 7) = '[' + FSettings.ECompName.Text + ']: PS ') and (Copy(SLOtmp.Strings[SLOtmp.Count - 1], Length(SLOtmp.Strings[SLOtmp.Count - 1]) - 1, 1) = '>')) then
20.    PZ.Tag := 0;
21.  end;
22.  
23.  if Assigned(SLOtmp) then SLOtmp.Free;
24. end;
25.  

The goal is to enter the remote powershell of another computer and get the result of each command I should run.
I previously used remote WMI commands (wmic.exe) but it is getting obsolete, I then used remote PowerShell commands (Get-CimInstance -computername) which are running correctly.
The PZReadData is something I found (maybe on this forum), I only added the prompt detection to exit.

The issue :
The issue is, according to me, related to my PZReadData procedure. The procedure works 99% of the time, but when it fails, I may be falling in my while loop. What I can say, is that the PowerShell commands are sometimes returning an unexpected result (missing result, broken format result and something I am not able to catch that fails my procedure).

I tried to log everything, I tried to put some timeouts, to workaround the issue, but each time it fails, I loop and the workaround is not working, so clearly, I am not handling the process correctly.

One workaround I found is the LazPwshJP64.dll in the topic,58276.0.html but I would like to understand what I am doing wrong and what I should do right, avoid using this additionnal DLL, avoid a blackbox dll I use blindly without understanding it.

Thanks

[Thaddy]

This is again an example that the stream source needs to be flushed before you can read that stream.

[HomeBoy38]

ok, I got the idea but can you tell me what/where/how I should do it?
I have found threads saying it is not necessary, some say to "closeoutput" (but I am afraid I will hang on the next command), ... so I am a bit lost

Note:
I am currently testing this:

Code: Pascal  [Select][+][-]

1. PZ.Tag := 1;
2. PZ.Input.Write(s[1], Length(s));
3. FileFlush(PZ.Output.Handle);        // Flush test
4. while PZ.Tag <> 0 do
5.  Application.HandleMessage;
6.  

Nope, after a few hours, loop of the death, either the flush try is not what was suggested, either the truth is out there