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 3 of the License, or
   8    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert.  */
  19
  20 #include <config.h>
  21
  22 #include "unistd-safer.h"
  23
  24 #include <fcntl.h>
  25
  26 #include <unistd.h>
  27 #ifndef STDERR_FILENO
  28 # define STDERR_FILENO 2
  29 #endif
  30
  31 /* Like dup, but do not return STDIN_FILENO, STDOUT_FILENO, or
  32    STDERR_FILENO.  */
  33
  34 int
  35 dup_safer (int fd)
  36 {
  37 #if defined F_DUPFD && !defined FCHDIR_REPLACEMENT
  38   return fcntl (fd, F_DUPFD, STDERR_FILENO + 1);
  39 #else
  40   /* fd_safer calls us back, but eventually the recursion unwinds and
  41      does the right thing.  */
  42   return fd_safer (dup (fd));
  43 #endif
  44 }