[SOLVED] Horrible console output
lazarus / 32-Linux

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lebao3105 · 2026-04-02 11:51

I was constantly trying to modify set of stdout+stderr attributes to
my liking:
1. Map NL to CR-NL, as LineEnding on Linux and many other OSes is only
NL
2. Disable mapping CR to NL
3. And maybe more if needed

termios attributes and flags can be found here:
https://www.man7.org/linux/man-pages/man3/termios.3.html

The code is here:
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    {
Where to write stuff into. }    OutputFile: Text;     { Handle to
where to write stuff into. }    OutputHandle: cint =
StdOutputHandle; { Check if Handle is a terminal. }fn
isATerminal(Handle: cint): bool; retn screenClear;retn
setOutputStream(toStdErr: bool);fn ANSIEscapeSequence(seq: string):
string; // other unrelevant parts of the unit are not
included implementation uses ... var    originalOuts: array[0..1] of
termios;    // 0st index: stdout    // 1st index: stderr fn
isATerminal(Handle: cint): bool;begin    return(isATTY(Handle) =
1);end; retn setOutputStream(toStdErr: bool);begin    if toStdErr then
begin        OutputFile := stderr;        OutputHandle :=
StdErrorHandle;    end    else begin        OutputFile := stdout;    
  OutputHandle := StdOutputHandle;    end;end; retn
modifyOutputHandle_Internal(for_stderr: bool);var    indx: int;    h:
cint;    modi: termios;{$push} {$warn 5057 off} // Local variable
seems to be not initializedbegin    if for_stderr then begin       
indx := 1;        h := StdErrorHandle;    end    else begin       
indx := 0;        h := StdOutputHandle;    end;     if not
isATerminal(h) then        return;     if tcgetattr(h,
originalOuts[indx]) = -1 then        return; // TODO: Do something   
modi := originalOuts[indx];    modi.c_oflag := modi.c_oflag or ONLCR; 
  modi.c_oflag := modi.c_oflag or ONLRET;    modi.c_oflag :=
modi.c_oflag or ONOCR;    modi.c_oflag := modi.c_oflag and not
OCRNL;     if tcsetattr(h, TCSANOW, modi) = -1 then        return; //
TODO: Do somethingend;{$pop} retn restoreStdOut_Internal(for_stderr:
bool);var    indx: int;    h: cint;begin    if for_stderr then begin 
     indx := 1;        h := StdErrorHandle;    end    else begin     
 indx := 0;        h := StdOutputHandle;    end;     if not
isATerminal(h) then        return;        if tcsetattr(h, TCSANOW,
originalOuts[indx]) = -1 then        return; // TODO: Do
somethingend; retn screenClear;begin    if not
isATerminal(OutputHandle) then        return;     write(OutputFile,
ESC_KEY+'[2J');    write(OutputFile, ESC_KEY+'[H'); // move the cursor
to the top-left cornerend; fn ANSIEscapeSequence(seq: string): string;
inline;begin    if isATerminal(OutputHandle) then        return(seq); 
  return('');end; initialization InitKeyboard; modifyOutputHandle_Inte
rnal({ for stderr }true);modifyOutputHandle_Internal(false); finalizat
ion DoneKeyboard; Debug('Restoring default console attributes...',
[]);if modifiedStdIn and not disableRawStdIn then        Error('Failed
to restore standard input attributes.', []); restoreStdOut_Internal({
for stderr }true);restoreStdOut_Internal(false); end. 
Broken output can be seen using program's --help option.
My program uses an array of TOption, which is:
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 type
TOption = record        Long    : String;        Kind    : EOptKind; 
     Short   : Char;        Help    : string;         { Write the full
help message of the option, which includes:          * Short and long
variants;          * Value parameter name - if any and the option
needs a value;          * Default option value - if any and the option
needs a value;          * The option's help message.        }       
fn WriteFullHelpMessage(defaultVal: string = ''; valParam: string =
'VALUE'): string;    end; fn TOption.WriteFullHelpMessage(defaultVal:
string = ''; valParam: string = 'VALUE'): string;begin    if Short =
#0 then        return;     Result += ANSI_CODE_BOLD;     if Long <> ''
then        Result += ('--' + Long + '  ');        // TOption.Short
must not be empty as it's used for command-    // line parsing task.
However ARGAs are terminated with 0ed    // entry, which of course has
its Short a #0. Already been    // handled above.    Result += ('-' +
Short + ANSI_CODE_RESET);     if Kind <> EOptKind.FLAG then    begin 
     if Long <> '' then Result += '  ';        Result += valParam;   
    if defaultVal <> '' then            Result += (' = ' +
defaultVal);     end;     Result += (LineEnding#9 + Help +
LineEnding);end; 
All TOption fields are not empty.

The problem is that not only NL is still not CRNL (as LineEnding is a
constant), but also garbage datas get printed and help messages get
(re)printed for unknown reason (I think it's not related to this
topic):
Code: [Select]Asks for user input.
                    M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue

M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user

M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               M=��RD�3=�4+@�AD�3=�4+@--message  -m  VALUE
        Custom message to show instead of Press any key/Enter to
continue
--hide-input  -t
        Hide inputs from the user
--require-enter
               -o will show characters from -k inside squared
brackets, e.g [ynYn].
If no arguments are provided, the program will simply ask for a key
press, quits with exit code 0.
Otherwise will quit with the exit code set to the ASCII value of the
input character.
                                                                     
              fatal: unrecognized option: -o
                                                                     
                                            debug: Restoring default
console attributes...

Removing stdout and stderr modifications on application start
(modifyOutputHandle_Internal calls) failed to work.

Are there any stdout/stderr modification from the RTL / C runtime that
I do not know to happen on program start? Are my modifications
actually correct? Should I manually override RTL's LineEnding to CRNL?

Hours later I may produce a small reproduction.

By the way, some compiler flags are used:
Code: [Select]-dretn:=procedure
-dfn:=function
-dlong:=longint
-dulong:=longword
-dint:=integer
-dbool:=boolean
-dreturn:=exit

Fix: To fix, use SetTextLineEnding:
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
SetTextLineEnding(stderr, #13#10);SetTextLineEnding(stdout, #13#10); 
However this does NOT work if you use literal NL / UNIX LineEnding.

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lebao3105 · 2026-04-02 15:40

As promised here is the reproduce program.
Oddly there are no garbage data being printed.
No additional compiler flags needed.

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lebao3105 · 2026-04-02 15:50

Here is the modified test.pp in order to actually require no other
compiler flags.

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Thaddy · 2026-04-02 16:30

That code is neither freepascal, nor delphi.
IGN what dialect are you using?

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lebao3105 · 2026-04-02 16:44

Quote from: Thaddy on April 02, 2026, 06:30:59 pmThat code is neither
freepascal, nor delphi.
IGN what dialect are you using?

Free Pascal?
For the original code, I just put some compiler definitions. The
lastest reproduce code however does not need any of them.

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lebao3105 · 2026-04-02 16:51

I figured out the cause of broken output indentations. It was...
InitKeyboard. Oh dear...
It literally set the console to use RAW mode.