On 06/09/2014 04:16 PM, Michael Goffioul wrote: > On Mon, Jun 9, 2014 at 11:03 AM, Eli Zaretskii <e...@gnu.org > <mailto:e...@gnu.org>> wrote: > > > Date: Mon, 09 Jun 2014 09:33:18 +0100 > > From: Pádraig Brady <p...@draigbrady.com> > > Cc: bug-gnulib@gnu.org <mailto: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
Thanks for the defails and double follow up Micheal. I'll apply the attached later. thanks, Pádraig.
>From a008d625b7854d2c08c6606d90f6f2f48263f973 Mon Sep 17 00:00:00 2001 From: Michael Goffioul <michael.goffi...@gmail.com> Date: Mon, 9 Jun 2014 17:07:44 +0100 Subject: [PATCH] isatty: fix to work on windows 8 * lib/isatty.c (IsConsoleHandle): Change from testing the lower 2 bits of the handle to the more expensive but accurate syscall. --- ChangeLog | 6 ++++++ lib/isatty.c | 8 +++++--- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/ChangeLog b/ChangeLog index 53be01f..fbb05bd 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2014-06-09 Michael Goffioul <michael.goffi...@gmail.com> + + isatty: fix to work on windows 8 + * lib/isatty.c (IsConsoleHandle): Change from testing the lower + 2 bits of the handle to the more expensive but accurate syscall. + 2014-06-07 Paul Eggert <egg...@cs.ucla.edu> maint: fix typo in fdl.texi diff --git a/lib/isatty.c b/lib/isatty.c index e38bc9d..7180ead 100644 --- a/lib/isatty.c +++ b/lib/isatty.c @@ -32,9 +32,11 @@ /* Get _get_osfhandle(). */ #include "msvc-nothrow.h" -/* Optimized test whether a HANDLE refers to a console. - See <http://lists.gnu.org/archive/html/bug-gnulib/2009-08/msg00065.html>. */ -#define IsConsoleHandle(h) (((intptr_t) (h) & 3) == 3) +static BOOL IsConsoleHandle (HANDLE h) +{ + DWORD mode; + return GetConsoleMode (h, &mode) != 0; +} #if HAVE_MSVC_INVALID_PARAMETER_HANDLER static int -- 1.7.7.6
