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      1 /* Invoke dup, but avoid some glitches.
      2    Copyright (C) 2001, 2004, 2005 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 2, or (at your option)
      7    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, write to the Free Software Foundation,
     16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
     17 
     18 /* Written by Paul Eggert.  */
     19 
     20 #ifdef HAVE_CONFIG_H
     21 # include <config.h>
     22 #endif
     23 
     24 #include "unistd-safer.h"
     25 
     26 #include <fcntl.h>
     27 
     28 #include <unistd.h>
     29 #ifndef STDERR_FILENO
     30 # define STDERR_FILENO 2
     31 #endif
     32 
     33 /* Like dup, but do not return STDIN_FILENO, STDOUT_FILENO, or
     34    STDERR_FILENO.  */
     35 
     36 int
     37 dup_safer (int fd)
     38 {
     39 #ifdef F_DUPFD
     40   return fcntl (fd, F_DUPFD, STDERR_FILENO + 1);
     41 #else
     42   /* fd_safer calls us back, but eventually the recursion unwinds and
     43      does the right thing.  */
     44   return fd_safer (dup (fd));
     45 #endif
     46 }
     47