Re: is_tty on mingw and msys

["David Brown" <david@...>]

> Hi,
>
> David Brown wrote:
> > I'm using w2k for development, compiling with mingw in an msys
environment.
> > Compilation (of lua 5.1) worked fine, as does running it from a standard
> > windows command prompt.  However, lua.exe produces no output by default
when
> > run from within msys.  I traced this down to the lua_stdin_is_tty()
macro in
> > luaconf.h - it would seem that _isatty() always returns 0 when running
from
> > msys.
>
> Well, I got bitten by _isatty() malfunctioning previously and
> tried to track this down:
>
> Both cmd.exe and Cygwin bash attach stdin to a real terminal and
> the _isatty logic works fine. Windows doesn't have pseudo-ttys,
> so they need to be emulated with pipes in certain situations. In
> a pure Cygwin environment, i.e. when Lua is compiled against
> Cygwin libraries, this is taken care of and still works.
>
> Alas, the MSYS shell always seems to use pipes (why?). But MinGW
> binaries are (intentionally) compiled against MSVCRT. Which has
> of course no knowledge about this emulation. That's why _isatty()
> returns 0 when run under MSYS shell.
>
> > For my own use, I've simply hacked the luaconf.h file to return 1
> > here, but perhaps there is a better solution?
>
> Probably not.
>
> Maybe someone has the time to take a deeper look at MSYS and fix
> this or report it as a potential bug.
>
> Bye,
>      Mike
>

I guess this is something that has to be fixed (if possible) by the MSYS
developers.  MSYS has always had compromises - avoiding the overhead the
cygwin pays, at the cost of not quite following posix and not quite
emulating everything.  For my own part, hacking luaconf.h (or just using
"lua -i") is fine.

Thanks for looking into it.

mvh.,

David