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/* Copyright (C) 1991, 1993 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>
/* Push the character C back onto the input stream of STREAM. */
int
DEFUN(ungetc, (c, stream), register int c AND register FILE *stream)
{
if (!__validfp(stream) || !stream->__mode.__read)
{
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;
}
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