contrib/grep/lib/isatty.c

   1 /* isatty() replacement.
   2    Copyright (C) 2012-2015 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <unistd.h>
  21
  22 /* This replacement is enabled on native Windows.  */
  23
  24 #include <errno.h>
  25
  26 /* Get declarations of the Win32 API functions.  */
  27 #define WIN32_LEAN_AND_MEAN
  28 #include <windows.h>
  29
  30 #include "msvc-inval.h"
  31
  32 /* Get _get_osfhandle().  */
  33 #include "msvc-nothrow.h"
  34
  35 static BOOL IsConsoleHandle (HANDLE h)
  36 {
  37   DWORD mode;
  38   return GetConsoleMode (h, &mode) != 0;
  39 }
  40
  41 #if HAVE_MSVC_INVALID_PARAMETER_HANDLER
  42 static int
  43 _isatty_nothrow (int fd)
  44 {
  45   int result;
  46
  47   TRY_MSVC_INVAL
  48     {
  49       result = _isatty (fd);
  50     }
  51   CATCH_MSVC_INVAL
  52     {
  53       result = 0;
  54     }
  55   DONE_MSVC_INVAL;
  56
  57   return result;
  58 }
  59 #else
  60 # define _isatty_nothrow _isatty
  61 #endif
  62
  63 /* Determine whether FD refers to a console device.  Return 1 if yes.
  64    Return 0 and set errno if no. (ptsname_r relies on the errno value.)  */
  65 int
  66 isatty (int fd)
  67 {
  68   HANDLE h = (HANDLE) _get_osfhandle (fd);
  69   if (h == INVALID_HANDLE_VALUE)
  70     {
  71       errno = EBADF;
  72       return 0;
  73     }
  74   /* _isatty (fd) tests whether GetFileType of the handle is FILE_TYPE_CHAR.
  75      But it does not set errno when it returns 0.  */
  76   if (_isatty_nothrow (fd))
  77     {
  78       if (IsConsoleHandle (h))
  79         return 1;
  80     }
  81   errno = ENOTTY;
  82   return 0;
  83 }