TAsyncProcess and Powershell
lazarus / 34-Windows

----------------------------------------------------------------------
HomeBoy38 · 2024-02-22 11:04

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][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var s :
String; SLO: TStringList; beginPZ.Executable :=
'C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe';PZ.Tag :=
1; // Process is runningSLO.Clear;s := 'Enter-PSSession ' + CompName +
LineEnding; // CompName is the computer name and LineEnding is
CRLFPZ.Input.Write(s[1], Length(s));while PZ.Tag <> 0 do 
Application.HandleMessage;... s := 'Invoke-Command {Get-WmiObject
Powershell Command}' + LineEnding; PZ.Tag := 1; PZ.Input.Write(s[1],
Length(s)); while PZ.Tag <> 0 do  Application.HandleMessage;... 
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TMainForm.PZReadData(Sender: TObject);var J: Integer; SLOtmp:
TStringList;begin J := 0; SLOtmp :=
TStringList.Create; SLOtmp.LoadFromStream(PZ.Output);  if J <
SLOtmp.Count then begin  for J := J to SLOtmp.Count - 1 do 
 SLO.Add(SLOtmp.Strings[J]); end;  if SLOtmp.Count > 0 then begin  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   
 ((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   PZ.Tag
:= 0; end;  if Assigned(SLOtmp) then SLOtmp.Free;end; 
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 · 2024-02-22 15:47

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

----------------------------------------------------------------------
HomeBoy38 · 2024-02-22 17:21

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][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i PZ.Tag :=
1;PZ.Input.Write(s[1], Length(s));FileFlush(PZ.Output.Handle);      
 // Flush testwhile PZ.Tag <> 0 do Application.HandleMessage; Nope,
after a few hours, loop of the death, either the flush try is not what
was suggested, either the truth is out there