Parsing STDERR / STDOUT

[pcurtis]

I use the following code to create a process (in a thread)

Code: Pascal  [Select][+][-]

1.   MyShell := TProcess.Create(nil);
2.     with MyShell do
3.       begin
4.         Options := [poUsePipes];
5.         ShowWindow := swoHIDE;
6.         Executable := 'D:\Lazarus\Shared\mpv.exe';
7.         Options := Options + [poUsePipes];
8.         Parameters.Add('--wid=' + inttostr(WID));
9.         while not MyQuery.EOF do
10.            begin
11.              Parameters.Add(MyQuery['fnPARAMETER'] + MyQuery['fnVALUE']);
12.              MyQuery.Next;
13.            end;
14.         Parameters.Add(ClipFilename);
15.         Execute;
16.       end;
17.  
18.     while (MyShell.Running) or
19.           (MyShell.Stderr.NumBytesAvailable > 0) do
20.       begin
21.         while MyShell.Stderr.NumBytesAvailable > 0 do
22.           begin
23.             fPlayVideoStatus := '';
24.             begin
25.               ReadCount := Min(512, MyShell.Stderr.NumBytesAvailable); //Read up to buffer, not more
26.               MyShell.Stderr.Read(CharBuffer, ReadCount);
27.  
28.               fPlayVideoStatus := fPlayVideoStatus + CharBuffer;
29.             end;
30.               fWhere := 1;
31.               Synchronize(@PlayVideoStatus);
32.           end;
33.  
34.         while MyShell.Output.NumBytesAvailable > 0 do
35.           begin
36.             fPlayVideoStatus := '';
37.               begin
38.                 ReadCount := Min(512, MyShell.Output.NumBytesAvailable); //Read up to buffer, not more
39.                 MyShell.Output.Read(CharBuffer, ReadCount);
40.  
41.                 fPlayVideoStatus := fPlayVideoStatus + CharBuffer;
42.               end;
43.  
44.             fWhere := 2;
45.             Synchronize(@PlayVideoStatus);
46.           end;
47.  
48.  

All works fine except parsing STDERR / STDOUT.

I would like to  Synchronize(@PlayVideoStatus) STDERR / STDOUT line by line (the sync code is fine). The problem really lyes in reading STDERR / STDOUT and parsing it.

I know @tedson has UnTerminal-1.0 that I think will do the trick, but I don't know how to integrate it.
Can anyone help?

[jamie]

What are you talking about, splitting lines when line endings appears and then generate a line of out as a string ?

[pcurtis]

So for example STDERR is read in 512 byte blocks. I want to break this into CRLF terminated strings. Data is constantly appearing on STDERR

[jamie]

Use string routines

MyDataString

When you start set it to '';

in the loop just treat the 512 buffer has array of char and add a 0 at the end of it each time to ensure the routines work..

MyDataString := MyDataString+Pchar(@My512Buffer)^;

empty the My512 for next read.

If Pos(#13, MyDataString) <> 0 Then
 
 Finalstring := Copy(…….) etc...

you know the rest...
I can give you example code block later...

[jamie]

Code: Pascal  [Select][+][-]

1. var
2.   Form1: TForm1;
3.   MyBufferList:TstringList; //Create this at start somewhere., keep it alive
4.  
5. implementation
6.  
7. {$R *.lfm}
8.  
9. { TForm1 }
10. Function StrFromMyBuf(Var theBuf:Array of Char;Count:Integer):TStringList;
11. Begin
12.   Result := MyBufferList;
13.   If Count = 0 Then exit;
14.   Result.SkipLastLineBreak :=True;
15.   Result.Text := Result.Text+Copy(Pchar(@Thebuf)^,0,Count-1);
16.   If Result.Count > 100 Then Result.Delete(0); //Keep list limited;
17. end;
18.  

Something like that.
that should give you something to work with.
make sure you empty the buffer each time you call this..

[jamie]

The last one won't work because for some reason the array isn't being past around correctly...

I did a local test with this one.

I am assuming because its a network thing that #10 will be the predominate line ending here but it will check for CR in case it gets in there.
Basically because if only a #13 is received then you can switch it around.. I suppose you could do a test to determine which order is being use..

This version requires that you maintain two items somewhere between calls.

Code: Pascal  [Select][+][-]

1. var
2.   Form1: TForm1;
3.   MyBufferList:TstringList; //Create this at start somewhere., keep it alive
4.   WorkString :String;
5. implementation
6.  
7. {$R *.lfm}
8.  
9. { TForm1 }
10. Function StrFromMyBuf(TheBuf:Pchar;Count:Integer):TStringList;
11. var
12.   E:Pchar;
13.   L:Integer;
14.   LE:Char;
15. Begin
16.   E := TheBuf; Inc(E,Count); //Mark the buffer end;
17.   L:= 0;
18.   While TheBuf < E DO
19.    Begin
20.     if TheBUf^ <> #10 Then WorkString := WorkString+TheBuf^ Else
21.      Begin
22.        While Pos(#13, WorkString)<>0 DO Delete(WorkString, Pos(#13,WorkString),1);
23.        MyBufferList.Add(WorkString);
24.        WorkString := '';
25.      end;
26.     Inc(TheBuf);
27.    end;
28. end;
29.                          
30.  

Cast your buffer to a PChar(@MyBuffer), Count etc..

[jamie]

Here is an example project using a class I wrote that can auto detect on the fly or line endings since I've found files that mix the line endings.

  This code is part of another project I did, I stripped out some stuff to keep it simple here but I ran into problems reading different files from sources of mixed line endings.

 Some had #13#10, others had only #10 or #3 and some had #10#13 etc..

In your case I stripped it down but you can add a TCriticalSection in the block read to protect it from multiple threads using the same instance..

Attached is a project..