coreutils/lib/fopen-safer.c
2001-03-03 19:05:36 +00:00

77 lines
1.6 KiB
C

/* Invoke fopen, but avoid some glitches.
Copyright (C) 2001 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Written by Paul Eggert. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
#if HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <unistd-safer.h>
#ifndef STDERR_FILENO
# define STDERR_FILENO 2
#endif
#include <errno.h>
#ifndef errno
extern int errno;
#endif
#include <stdio.h>
#include <stdio-safer.h>
/* Like fopen, but do not return stdin, stdout, or stderr. */
FILE *
fopen_safer (char const *file, char const *mode)
{
FILE *fp = fopen (file, mode);
if (fp)
{
int fd = fileno (fp);
if (0 <= fd && fd <= STDERR_FILENO)
{
int f = dup_safer (fd);
if (f < 0)
{
int e = errno;
fclose (fp);
errno = e;
return NULL;
}
if (fclose (fp) != 0
|| ! (fp = fdopen (f, mode)))
{
int e = errno;
close (f);
errno = e;
return NULL;
}
}
}
return fp;
}