ungetc.c revision 7257d1b4d25bfac0c802847390e98a464fd787ac
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1988 AT&T */
/* All Rights Reserved */
#pragma ident "%Z%%M% %I% %E% SMI"
#include "lint.h"
#include "file64.h"
#include "mtlib.h"
#include <sys/types.h>
#include <stdio.h>
#include <thread.h>
#include <synch.h>
#include "stdiom.h"
int _ungetc_unlocked(int c, FILE *iop);
int
ungetc(int c, FILE *iop)
{
FLOCKRETURN(iop, _ungetc_unlocked(c, iop))
}
/*
* Called internally by the library (instead of the safe "ungetc") when
* iop->_lock is already held at a higher level - required since we do not
* have recursive locks.
*/
int
_ungetc_unlocked(int c, FILE *iop)
{
if (c == EOF)
return (EOF);
if (iop->_ptr <= iop->_base) {
if (iop->_base == 0) {
if (_findbuf(iop) == 0)
return (EOF);
} else if (iop->_ptr <= iop->_base - PUSHBACK)
return (EOF);
}
if ((iop->_flag & _IOREAD) == 0) /* basically a no-op on write stream */
++iop->_ptr;
if (*--iop->_ptr != (unsigned char) c)
*iop->_ptr = (unsigned char) c; /* was *--iop->_ptr = c; */
++iop->_cnt;
iop->_flag &= ~_IOEOF;
return (c);
}