TOPIC:

Hi Guys

Not sure if this is the correct forum but;

I have an application that I wrote in mid 2022.
The app is designed for GNU/Linux. It uses TProcess to write to stdin of other processes.
The app requires some minor update and today, after a rebuild using the latest Typhon64 8.60, I discovered that
sending strings via TProcess to external process fails.
Don't know if something changed in later FPC or in Linux libs.

Details of system:
OS: Debian GNU/Linux 12 with latest updates

Code that no longer works since ver 8.21

//

---

//* Send data to process's STDIN //* nino 24-08-2022
//

---

if (_iList <> nil) and (_iList.Count > 0) then
begin
Strg := _iList.Text;

Process.Input.Write(Strg[1], Length(Strg));
Process.CloseInput();
end;
//

---

Full function code include:

//

---

//* If we don't know the size of the output, we cannot use poWaitOnExit.
//* On Linux the size of output pipe is 2 kB.
//* If the output data is more, we need to read the data.
//* This isn't possible if we are waiting, so we would get a deadlock here.
//* The Wait parameter default value is wsNoWait.
//* Use Wait = wsWait when you need to wait for a process with little output.
//*
//* CommandLine parameters are passed via [_pList]. One parameter per line please!
//*
//* Environment strings, as name/value pairs, are passed to the
//* executable via [_eList] if [_eList] if supplied.
//*
//* Data passed via [_iList] will be passed to the process's STDIN
//*
//* A temp Memorystream is used to buffer the output from STDOUT.
//* A temp Memorystream is used to buffer the output from STDERR.
//*
//* The buffer output is copied into [_sList] if [_sList] if supplied.
//*
//* If the command in [_CommandLine] causes an error, [_sList] will contain
//* the output that would normally go to STDERR.
//*
//* Returns True on command execution success (output from STDOUT)
//* Returns False on command execution failure (output from STDERR)
//

---

function ExecProcessEx(const _Executable : string; //* NL - 27 Oct 2022
_pList : TStringList = nil; //* CMD Line Param list
_sList : TStringList = nil; //* List to where the buffer output is copied
_eList : TStringList = nil; //* Environment strings to pass, as name/value pairs
_iList : TStringList = nil; //* Data to be passed to the process's STDIN
_Wait : TWaitState = wsNoWait) : Boolean;
const
READ_BYTES = 20480;

var
OutCount : LongInt;
ErrCount : LongInt;
OutBytesRead : LongInt;
ErrBytesRead : LongInt;
Done : Boolean;
Strg : string;
ProcessCMDLine : string;
Process : TProcess;
OutStream : TMemoryStream;
ErrStream : TMemoryStream;

begin
OutStream := TMemoryStream.Create();
ErrStream := TMemoryStream.Create();

try
OutBytesRead := 0;
ErrBytesRead := 0;

Process := TProcess.Create(nil);
try
ProcessCMDLine := _Executable; //* nino 14-05-2011

if _CheckIfShellRequired(ProcessCMDLine, _Executable) then
Process.CommandLine := ProcessCMDLine //* nino 24-10-2014
else
Process.Executable := _Executable;

//* Add Command Line Parameters
if _pList <> nil then
Process.Parameters := _pList; //* nino 27-10-2022

//* Set environment variables
if _eList <> nil then //* nino 13-06-2015
Process.Environment := _eList;

{$ifdef nl_debug}
Writeln(Process.CommandLine);
{$endif}

case _Wait of
wsWait : Process.Options := [poWaitOnExit, poUsePipes];
wsNoWait : Process.Options := [poUsePipes];
end; //* case.

try
//* Run the process.
Process.Execute();

//

---

//* Send data to process's STDIN //* nino 24-08-2022
//

---

if (_iList <> nil) and (_iList.Count > 0) then
begin
Strg := _iList.Text;

Process.Input.Write(Strg[1], Length(Strg));
Process.CloseInput();
end;
//

---

except
Result := False;
_sList.Clear();
_sList.Add('unknown process error [nl_exec.ExecProcessEx()]');
Exit;
end;

Done := False;

//* Accumulate all process output and/or error output.
while not Done do
begin
//* make sure we have room
OutStream.SetSize(OutBytesRead + READ_BYTES);
ErrStream.SetSize(ErrBytesRead + READ_BYTES);

//* try reading it.
OutCount := Process.Output.Read((OutStream.Memory + OutBytesRead)^, READ_BYTES);
ErrCount := Process.Stderr.Read((ErrStream.Memory + ErrBytesRead)^, READ_BYTES);

if OutCount > 0 then
Inc(OutBytesRead, OutCount);

if ErrCount > 0 then
Inc(ErrBytesRead, ErrCount);

if (OutCount = 0) and (ErrCount = 0) then
Done := True;
end;

OutStream.SetSize(OutBytesRead);
ErrStream.SetSize(ErrBytesRead);

//* Copy Stream into sList.
if _sList <> nil then
begin
Result := True;
_sList.LoadFromStream(OutStream);

//* if OutStream is empty, copy ErrStream into [_sList]
if _sList.Count = 0 then
begin
_sList.LoadFromStream(ErrStream);
Result := False;
end;
end;

finally
SafeFreeAndNil(Process);
end;

finally
SafeFreeAndNil(ErrStream);
SafeFreeAndNil(OutStream);
end;
end;

Thanks Sir
We are preparing the new LAB release of CT ver 8.70,
with a lot of work...

So, please, give us time to test your code and report here.
 

Hi Matis

In Class TProcess, the following line of code is not working in CodeTyphon since version 8,3 to current.

Process.Input.Write(Strg[1], Length(Strg));

Please check on your side. Code works when using the latest official Free Pascal version 3.2.2

Sir
the TProcess code (codetyphon/fpcsrc/packages/fcl-process/src/)
after CT 8.3 is the same with FreePascal 3.3.1 trunk. 

We will try to fix this,
but please attach a test project for our tests
 

Hi Matis,

test.tar.gz file attached. Refer to included READ.ME file for simple build and run instructions.

Thanks

With FreePascal 3.3.1 trunk TProcess don't work in your projects as you want..

It's NOT so simple....

My Suggestion 

-Replace pl_CMDRunner pkg in your CT with the attach ver 8.7.1
-Open and compile pl_CMDRunner pkg ver 8.7.1
-Add pl_CMDRunner pkg to your project "input_sender"
-Replace in uses of this project, -Process with ctProcess
-Test

Screen of Latest Fedora 42 MATE with TyphonIDE build for QT6.

 

I hope this to solve the problem
Have fun...


 

Thank you Matis, will test.

Am I understanding correctly that TProcess in FreePascal 3.3.1 trunk is buggy?
or Has something else changed in FreePascal 3.3.1 trunk that changed the way that TProcess works?

TProcess in FreePascal 3.3.1 Trunk has a lot of changes
from FreePascal 3.2.2.


FreePascal 3.3.1 Trunk is a compiler with a lot of "Internal ERRORs"....   

Not only this
For our LAB staff It's a "drama" to keep trunk FPC version in CodeTyphon
Many many Fixes after real tests on 9 OSes and 10 CrossTargets.

I hear you Sternas. Thanks to you and your team for all your efforts. Whilst I do understand and support ongoing changes and improvements
to the Free Pascal compiler, would it be possible to have a more stable Typhon environment using a stable Free Pascal compiler version?
Something the likes of Debian distro in the Linux world, where stability is valued over the latest packages etc.

Once again, thank you for all the hard work and efforts you guys put into your software.