On Mon, Jun 9, 2014 at 11:03 AM, Eli Zaretskii <e...@gnu.org> wrote: > > Date: Mon, 09 Jun 2014 09:33:18 +0100 > > From: Pádraig Brady <p...@draigbrady.com> > > Cc: bug-gnulib@gnu.org > > > > It's an optimized test rather than an optimization for isatty() itself. > > Without this call the isatty() replacement is moot because the > > reason it exists on mingw is to double check the handle as there > > true is returned for the NUL device. > > Indeed, that's the main reason why just isatty is not enough. > > > > More importantly, it breaks on Windows 8, where all handles are > multiples of 4. The result is a false negative, and an unclean output from > a freshly compiled glib. > > > > Ugh fair enough. So it seems these lower 2 bits are still significant, > > just not used for tagging consoles any more? > > So is isatty(nul_handle) still returning true there? > > If not, then we could use a direct test of isatty(nul_handle) > > to enable the replacement. > > Note also the replacement is useful on "MSVC 9" to avoid an > > exception for isatty(invalid_handle), which we'd have to consider. > > You can call one of the console functions to test if a handle is > connected to a console. E.g., GetConsoleMode for the input handle and > GetConsoleScreenBufferInfo for output. These functions fail when the > handle is not a console handle. > > See the following threads, with problem reporting and solution testing: http://lists.gnu.org/archive/html/bug-gnulib/2012-12/msg00092.html http://lists.gnu.org/archive/html/bug-gnulib/2013-01/msg00007.html
Michael.
