Read output from Process in custiom action dont return symbols selected language Wix - wix

Question

I use the same code in custom action wix and console app. In custom action it dont return polish symbol "ł" and "ą" in custom action. Replaces them with other symbols or spaces. In console app it works well.
Already in the "message" variable there isnt polish letters.
private static void RunTest(Session session)
{
try
{
Process p = CreateProcess();
p.StartInfo.FileName = "....exe"; ;
p.StartInfo.Arguments = "-t";
string message = "";
int errorCount = 0;
p.OutputDataReceived += (sender, args) =>
{
if (args.Data == null)
return;
message += args.Data;
message += "\n";
};
p.ErrorDataReceived += (sender, args) =>
{
if (args.Data == null)
return;
errorCount++;
message += args.Data;
message += "\n";
};
p.Start();
p.BeginOutputReadLine();
p.WaitForExit();
SaveNewRtf(session, message);
}
catch (Exception)
{
}
}
private static Process CreateProcess()
{
Process p = new Process();
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.RedirectStandardError = true;
p.StartInfo.CreateNoWindow = true;
return p;
}
Edit:
This is happen because Massages from Process are in Unicode. But unfortunately I don't know how repair that. I changed encoding to utf-8 for messages in Program I run by Process and still the message are download in Unicode.

Answer 1

I solved it by
p.StartInfo.StandardOutputEncoding = OemEncoding.GetDefaultOemCodePageEncoding();
and
public static class OemEncoding
{
private const Int32 MAX_DEFAULTCHAR = 2;
private const Int32 MAX_LEADBYTES = 12;
private const Int32 MAX_PATH = 260;
private const UInt32 CP_OEMCP = 1;
public static Encoding GetDefaultOemCodePageEncoding()
{
CPINFOEX cpInfoEx;
if (GetCPInfoEx(CP_OEMCP, 0, out cpInfoEx) == 0)
throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture,
"GetCPInfoEx() failed with error code {0}",
Marshal.GetLastWin32Error()));
return Encoding.GetEncoding((int)cpInfoEx.CodePage);
}
[DllImport("Kernel32.dll", EntryPoint = "GetCPInfoExW", SetLastError = true)]
private static extern Int32 GetCPInfoEx(UInt32 CodePage, UInt32 dwFlags, out CPINFOEX lpCPInfoEx);
[StructLayout(LayoutKind.Sequential)]
private unsafe struct CPINFOEX
{
internal UInt32 MaxCharSize;
internal fixed Byte DefaultChar[MAX_DEFAULTCHAR];
internal fixed Byte LeadByte[MAX_LEADBYTES];
internal Char UnicodeDefaultChar;
internal UInt32 CodePage;
internal fixed Char CodePageName[MAX_PATH];
}
}