[xmlsec] non us-ascii filenames in user locale

[Aleksey Sanin]

 > Oh, you need also an easy autoreply for all these "but it works on NT"
 > posts which follow :-)

Well, the interesting thing is that it might not be that bad. We have
this problem, because NT allows one to have Unicode filenames. Thus,
you can have Russian filename on Windows NT box with German default
locale. AFAIK, this does not work on Win9x and the Russian filename
would be corrupted (i.e. it will have all these '?' characters) if
the default locale is not Russian.

A long time ago when I was doing client programming, the full solution
for this problem was pretty complex. The interesting fact is that while
_wfopen() function is not implemented on Win9x, the stub for this
function is still present in MSVC runtime dll. This means that you can
use this function in your program and the program will be loaded
correctly (the function will be found in the dll!) but when you try to
call it, you'll get an error back. Thus the solution was the following:
1) Function XYZ() always accepts UTF8 string for the filename.
2) In runtime, function XYZ() determines the operating system and
    - if it is WinNT then filename is converted from UTF8 to UCS2 and
      _wfopen() function is used
    - if it is Win9x then filename is converted from UTF8 to current
      locale, fopen() function is used and programmer crosses his/her
      fingers that user never has a filename in different locale.

Not sure if this is an overkill for LibXML2 or not but this is the best
solution for this problem I know.

Aleksey