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[Chebmaster]

This mighty Cheb finally wrangled unicode paths into submission!

I've successfully ran my engine in GL ES 2 mode from a folder named D:\／人◕‿‿◕人＼ while it contains ANGLE DLLs ripped from old Firefox, which are NOT unicode - i.e. they crash and burn if loaded from a path not representable in the system 8-bit encoding (CP1251 in my case).

This is how:

  function GetAnsiSafePath(s: TFileNameString): TFileNameString;
  {$ifndef windows}
  begin
    Result:= s;
  end;  
  {$else}
  // ASSUMING that the file name is safe anyway
  var
    u, b: UnicodeString;
    reqlen: dword;
    fn, pt: TFileNameString; 
    a: Array of UnicodeString;
    i: integer;
  begin
    if Length(s) = 0 then Exit(s);
    fn:= ExtractFileName(s);
    // first, optimize the path correcting slashes and collapsing all '\..\'
    pt:= OptiPath(ExtractFilePath(s));
    u:= FileNameToUnicode(pt);
    if IsPathAnsiSafe(u) then Exit(s);
    a:= Explode('\', u);
    u:= a[0] + '\'; // assuming its the drive letter, not checking
    for i:= 1 to High(a) - 1 do begin
      u+= a[i] + '\';
      if IsPathAnsiSafe(u) then continue;

      reqlen:= GetShortPathNameW(@u[1], nil, 0); //msdn sayd NOT INCLUDING
        // the terminating #0 but then where does that extra space
        // come from?
      if reqlen = 0 then begin
        GetLastError; // clear the error message
        Exit(s);
      end;
      SetLength(b, reqlen); // automatically creates extra space for the terminating zero
      SetLength(b, GetShortPathNameW(@u[1], @b[1], reqlen + 1));
      if Length(b) = 0 then Exit(s);
      u:= b;
    end;
    Result:= UnicodeToFileName(u) + fn;
  end;
  {$endif}

, where OptiPath is my custom path parser that collapses relative paths containing '\..\', UnicodeToFileName and so on are from my chtonic patch for fpc where TFileNameString = Utf8String even in Windows (I don't use lazarus libraries, implemented everything on my own) and IsPathAnsiSafe is this:

function IsPathAnsiSafe(u: UnicodeString): boolean;
{$ifndef windows}
begin Result:= Yes end;
{$else windows}
var 
  a: UnicodeString;
  b: AnsiString;
  i: integer;
  res: longbool;
  ac: AnsiChar;
begin
  if Length(u) < 1 then Exit(Yes);
  
  res:= false;
  i:= WideCharToMultiByte(CP_ACP, WC_COMPOSITECHECK or WC_DISCARDNS, 
                                           @u[1], length(u), nil, 0, nil, nil);
  if i < 1 then Exit(Yes); // graceful degradation
  SetLength(b, i);
  ac:= #7;
  WideCharToMultiByte(CP_ACP, WC_COMPOSITECHECK or WC_DISCARDNS,
                                        @u[1], length(u), @b[1], i, @ac, @res);
  Result:= Yes;
  for i:= 1 to Length(b) do
    if ord(b[i]) < 32 then begin
      Result:= No;
      break;
    end; 
end;
{$endif windows}

Aaaand, it worked!

Loading d:\84BC~1\3rdparty\ANGLE\win32\libGLESv2.dll...Ok, d:\84BC~1\3rdparty\ANGLE\win32\libGLESv2.dll
Loading d:\84BC~1\3rdparty\ANGLE\win32\libEGL.dll...Ok, d:\84BC~1\3rdparty\ANGLE\win32\libEGL.dll
Loading the procedure addresses from the GL ES DLL ...
glActiveTexture() at 5F1742C0h in d:\84BC~1\3rdparty\ANGLE\win32\libGLESv2.dll
glAttachShader() at 5F1742C5h in d:\84BC~1\3rdparty\ANGLE\win32\libGLESv2.dll
glBindAttribLocation() at 5F1742CAh in d:\84BC~1\3rdparty\ANGLE\win32\libGLESv2.dll
glBindBuffer() at 5F1742CFh in d:\84BC~1\3rdparty\ANGLE\win32\libGLESv2.dll

P.S. I had unhealthy obsession with redefining true and false as "Yes" and "No". I still follow this in my engine as it became standard.

P.P.S. This was a big problem in WinXP as it used user's name for that user's home directory. Use one non-unicode character and suddenly lots of software crash on you. Including anything compiled in fpc.
I'm not sure if later windozes resolved that.