Capture Console in Delphi 2009 and above

Question

The code below works for Delphi XE, but the 2400 buffersize is pretty ugly.

Anyone have some suggestions on cleaning this routine up ?? And making the 2400 limit disappear (without defining a 64000 buffer).

Thanks

procedure TForm1.Button1Click(Sender: TObject);
begin
     CaptureConsoleOutput('c:\windows\system32\ipconfig','',Memo1);
end;


procedure TForm1.CaptureConsoleOutput(const ACommand, AParameters: String; AMemo: TMemo);
 const
   CReadBuffer = 2400;
 var
   saSecurity: TSecurityAttributes;
   hRead: THandle;
   hWrite: THandle;
   suiStartup: TStartupInfo;
   piProcess: TProcessInformation;
   pBuffer: array[0..CReadBuffer] of AnsiChar;
   dRead: DWord;
   dRunning: DWord;
 begin
   saSecurity.nLength := SizeOf(TSecurityAttributes);
   saSecurity.bInheritHandle := True;
   saSecurity.lpSecurityDescriptor := nil;

if CreatePipe(hRead, hWrite, @saSecurity, 0) then
   begin
     FillChar(suiStartup, SizeOf(TStartupInfo), #0);
     suiStartup.cb := SizeOf(TStartupInfo);
     suiStartup.hStdInput := hRead;
     suiStartup.hStdOutput := hWrite;
     suiStartup.hStdError := hWrite;
     suiStartup.dwFlags := STARTF_USESTDHANDLES or STARTF_USESHOWWINDOW;
     suiStartup.wShowWindow := SW_HIDE;

 if CreateProcess(nil, PChar(ACommand + ' ' + AParameters), @saSecurity,
   @saSecurity, True, NORMAL_PRIORITY_CLASS, nil, nil, suiStartup, piProcess)
   then
 begin
   repeat
     dRunning  := WaitForSingleObject(piProcess.hProcess, 100);
     Application.ProcessMessages();
     repeat
       dRead := 0;
       ReadFile(hRead, pBuffer[0], CReadBuffer, dRead, nil);
       pBuffer[dRead] := #0;

       OemToAnsi(pBuffer, pBuffer);
       AMemo.Lines.Add(String(pBuffer));
     until (dRead < CReadBuffer);
   until (dRunning <> WAIT_TIMEOUT);
   CloseHandle(piProcess.hProcess);
   CloseHandle(piProcess.hThread);
 end;

 CloseHandle(hRead);
 CloseHandle(hWrite);


end;
end;

Answer 1

I've got some code that does this. I've hacked out various irrelevant bits, so this may not compile as is. But you should get the idea:

  procedure ReadStdout(hstdout: THandle; out stdout: string);
  var
    Buffer: AnsiString;
    FileSize: DWORD;
    NumberOfBytesRead: DWORD;
  begin
    FileSize := SetFilePointer(hstdout, 0, nil, FILE_END);
    if FileSize>0 then begin
      SetLength(Buffer, FileSize);
      SetFilePointer(hstdout, 0, nil, FILE_BEGIN);
      ReadFile(hstdout, Buffer[1], FileSize, NumberOfBytesRead, nil);
      //should really check that NumberOfBytesRead=FileSize
      stdout := Buffer;
    end else begin
      stdout := '';
    end;
  end;

  function CreateFileHandle(const FileName: string): THandle;
  var
    SecurityAttributes: TSecurityAttributes;
  begin
    ZeroMemory(@SecurityAttributes, SizeOf(SecurityAttributes));
    SecurityAttributes.nLength := SizeOf(SecurityAttributes);
    SecurityAttributes.lpSecurityDescriptor := nil;
    SecurityAttributes.bInheritHandle := True;
    Result := CreateFile(
      PChar(FileName),
      GENERIC_READ or GENERIC_WRITE,
      FILE_SHARE_READ or FILE_SHARE_WRITE,
      @SecurityAttributes,
      CREATE_ALWAYS,
      FILE_ATTRIBUTE_NORMAL or FILE_FLAG_WRITE_THROUGH,
      0
    );
  end;

  procedure Execute(const ExecutableFileName, DataFileName, TempFolder: string);
  var        
    hstdin, hstdout: THandle;
    StartupInfo: TStartupInfo;
    ProcessInfo: TProcessInformation;
    ExitCode: DWORD;
    stdout: string;
  begin
    hstdin := CreateFileHandle(TempFolder+'stdin');
    hstdout := CreateFileHandle(TempFolder+'stdout');
    Try
      ZeroMemory(@StartupInfo, SizeOf(StartupInfo));
      StartupInfo.cb := SizeOf(StartupInfo);
      StartupInfo.dwFlags := STARTF_USESHOWWINDOW or STARTF_USESTDHANDLES;
      StartupInfo.wShowWindow := SW_HIDE;
      StartupInfo.hStdInput := hstdin;
      StartupInfo.hStdError := hstdout;
      if CreateProcess(
        PChar(ExecutableFileName),
        '',
        nil,
        nil,
        True,
        CREATE_NO_WINDOW or NORMAL_PRIORITY_CLASS,
        nil,
        PChar(TempFolder),
        StartupInfo,
        ProcessInfo
      ) then begin            
        Try
          WaitForSingleObject(ProcessInfo.hProcess, INFINITE);
          GetExitCodeProcess(ProcessInfo.hProcess, ExitCode);
          ReadStdout(hstdout, stdout);
        Finally
          CloseHandle(ProcessInfo.hProcess);
          CloseHandle(ProcessInfo.hThread);
        End;
      end else begin
        //error;
      end;
    Finally
      CloseHandle(hstdout);
      CloseHandle(hstdin);
    End;
  end;

You'll want to clean up the temp files at some point.