glibc/stdio/freopen.c

75 lines
2.2 KiB
C

/* Copyright (C) 1991, 1994, 1995 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <errno.h>
#include <stdio.h>
/* Defined in fopen.c. */
extern int __getmode __P ((const char *, __io_mode *));
/* Defined in sysd-stdio.c. */
extern int __stdio_reopen __P ((const char *filename, __io_mode mode,
PTR *cookieptr, __io_close_fn closefn));
/* Replace STREAM, opening it on FILENAME. */
FILE *
DEFUN(freopen, (filename, mode, stream),
CONST char *filename AND CONST char *mode AND register FILE *stream)
{
__io_mode m;
PTR cookie;
if (!__getmode (mode, &m))
{
(void) fclose (stream);
errno = EINVAL;
return NULL;
}
if (stream->__mode.__write)
/* Flush the stream. */
(void) fflush (stream);
/* Open the file, attempting to preserve the old cookie value. */
cookie = stream->__cookie;
if (__stdio_reopen (filename, m, &cookie,
stream->__seen ?
stream->__io_funcs.__close :
__stdio_close))
{
int save = errno;
(void) fclose (stream);
errno = save;
return NULL;
}
/* Close the stream, first disabling its cookie close function because
__stdio_reopen has already dealt with closing the old cookie. */
stream->__seen = 1; /* It might have no functions yet. */
stream->__io_funcs.__close = NULL;
(void) fclose (stream);
stream->__magic = _IOMAGIC;
stream->__cookie = cookie;
stream->__mode = m;
return stream;
}