Re: [PATCH 3/3] fhandler_pty_slave::setup_locale: respect charset == "UTF-8"

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

On Sep  2 17:24, Corinna Vinschen wrote:
> On Sep  2 19:54, Takashi Yano via Cygwin-patches wrote:
> > Hi Corinna,
> > 
> > On Wed, 2 Sep 2020 10:38:18 +0200
> > Corinna Vinschen wrote:
> > > On Sep  2 10:30, Corinna Vinschen wrote:
> > > > Ok guys, I'm not opposed to this change in terms of its result,
> > > > but I'm starting to wonder why all this locale code in fhandler_tty
> > > > is necessary at all.
> > > > 
> > > > I see that get_langinfo() calls __loadlocale and performs a lot of stuff
> > > > on the charsets which looks like duplicates of the initial_setlocale()
> > > > call performed at DLL startup.
> > > > 
> > > > If there's anything missing in the initial_setlocale() call which would
> > > > be required by the pseudo tty code?  What exactly is it?  The codepage?
> > > > And why can't we just add the info to cygheap->locale at initial_setlocale()
> > > > time so it's available at exec time without going through all this hassle
> > > > every time?
> > > > 
> > > > Apart from that, all this locale/charset/lcid stuff should be concentrated
> > > > in nlsfunc.cc ideally.
> > > 
> > > get_locale_from_env() and get_langinfo() should go away.  If we just
> > > need a codepage for get_ttyp ()->term_code_page, we should really find a
> > > way to do this from within internal_setlocale().
> > 
> > I looked into internal_setlocale() code, but I could not found
> > the code which handles thecode page. I found the code handling
> > the code page in __set_charset_from_locale() function in nlsfuncs.cc,
> > but it does not return code page itself. Could you please explain
> > more detail of your idea?
> 
> I had none yet :)  I was just musing, without actually thinking about a
> solution.  But I think this isn't very complicated.  Given this is
> inside Cygwin, nothing keeps the function to have a well-defined
> side-effect, as in setting a (not yet existing) member "term_code_page"
> of cygheap->locale.
> 
> Kind of like this:

Actually, this is a bit too simple, but you get the idea.  We need to
align the terminal codepage with the actual Cygwin charset, along the
lines of what your setup_locale is doing standalone yet.  Except in case
of ASCII, where we default to UTF-8 internally.  The important part here
is that we do this once, and that we don't have unnecessary code
duplication.


Corinna