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/* stdopen.c - ensure that the three standard file descriptors are in use
Copyright (C) 2005 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 2, 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, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by Paul Eggert and Jim Meyering. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include "stdopen.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#ifndef STDIN_FILENO
# define STDIN_FILENO 0
#endif
#ifndef STDOUT_FILENO
# define STDOUT_FILENO 1
#endif
#ifndef STDERR_FILENO
# define STDERR_FILENO 2
#endif
/* Try to ensure that each of the standard file numbers (0, 1, 2)
is in use. Without this, each application would have to guard
every call to open, dup, and fopen with tests to ensure they don't
use one of the special file numbers when opening a user's file. */
void
stdopen (void)
{
int fd = dup (STDIN_FILENO);
if (0 <= fd)
close (fd);
else if (errno == EBADF)
fd = open ("/dev/null", O_WRONLY);
if (STDIN_FILENO <= fd && fd <= STDERR_FILENO)
{
fd = open ("/dev/null", O_RDONLY);
if (fd == STDOUT_FILENO)
fd = dup (fd);
if (STDERR_FILENO < fd)
close (fd);
}
}
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