gl/dup-safer.c

   1 /* Invoke dup, but avoid some glitches.
   2
   3    Copyright (C) 2001, 2004, 2005, 2006 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 /* Written by Paul Eggert.  */
  20
  21 #include <config.h>
  22
  23 #include "unistd-safer.h"
  24
  25 #include <fcntl.h>
  26
  27 #include <unistd.h>
  28 #ifndef STDERR_FILENO
  29 # define STDERR_FILENO 2
  30 #endif
  31
  32 /* Like dup, but do not return STDIN_FILENO, STDOUT_FILENO, or
  33    STDERR_FILENO.  */
  34
  35 int
  36 dup_safer (int fd)
  37 {
  38 #if defined F_DUPFD && !defined FCHDIR_REPLACEMENT
  39   return fcntl (fd, F_DUPFD, STDERR_FILENO + 1);
  40 #else
  41   /* fd_safer calls us back, but eventually the recursion unwinds and
  42      does the right thing.  */
  43   return fd_safer (dup (fd));
  44 #endif
  45 }