dup-safer.c

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/* Invoke dup, but avoid some glitches.

   Copyright (C) 2001, 2004, 2005, 2006 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Written by Paul Eggert.  */

#include <config.h>

#include "unistd-safer.h"

#include <fcntl.h>

#include <unistd.h>
#ifndef STDERR_FILENO
# define STDERR_FILENO 2
#endif

/* Like dup, but do not return STDIN_FILENO, STDOUT_FILENO, or
   STDERR_FILENO.  */

int
dup_safer (int fd)
{
#if defined F_DUPFD && !defined FCHDIR_REPLACEMENT
  return fcntl (fd, F_DUPFD, STDERR_FILENO + 1);
#else
  /* fd_safer calls us back, but eventually the recursion unwinds and
     does the right thing.  */
  return fd_safer (dup (fd));
#endif
}