60 lines
1.9 KiB
C
60 lines
1.9 KiB
C
/* Copyright (C) 1991, 1993, 1996, 1997 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., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include <errno.h>
|
|
#include <stdio.h>
|
|
|
|
|
|
/* Push the character C back onto the input stream of STREAM. */
|
|
int
|
|
ungetc (c, stream)
|
|
int c;
|
|
FILE *stream;
|
|
{
|
|
if (!__validfp (stream) || !stream->__mode.__read)
|
|
{
|
|
__set_errno (EINVAL);
|
|
return EOF;
|
|
}
|
|
|
|
if (c == EOF)
|
|
return EOF;
|
|
|
|
if (stream->__pushed_back)
|
|
/* There is already a char pushed back. */
|
|
return EOF;
|
|
|
|
if ((stream->__linebuf_active || stream->__put_limit > stream->__buffer) &&
|
|
/* This is a read-write stream with something in its buffer.
|
|
Flush the stream. */
|
|
__flshfp (stream, EOF) == EOF)
|
|
return EOF;
|
|
|
|
stream->__pushback = (unsigned char) c;
|
|
/* Tell __fillbf we've pushed back a char. */
|
|
stream->__pushed_back = 1;
|
|
stream->__pushback_bufp = stream->__bufp;
|
|
/* Make the next getc call __fillbf. It will return C. */
|
|
stream->__bufp = stream->__get_limit;
|
|
|
|
/* We just gave it another character to read, so it's not at EOF. */
|
|
stream->__eof = 0;
|
|
|
|
return stream->__pushback;
|
|
}
|