xref: /onnv-gate/usr/src/lib/libc/port/stdio/ungetc.c (revision 6812:febeba71273d)
10Sstevel@tonic-gate /*
20Sstevel@tonic-gate  * CDDL HEADER START
30Sstevel@tonic-gate  *
40Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*6812Sraf  * Common Development and Distribution License (the "License").
6*6812Sraf  * You may not use this file except in compliance with the License.
70Sstevel@tonic-gate  *
80Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
90Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
100Sstevel@tonic-gate  * See the License for the specific language governing permissions
110Sstevel@tonic-gate  * and limitations under the License.
120Sstevel@tonic-gate  *
130Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
140Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
150Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
160Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
170Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
180Sstevel@tonic-gate  *
190Sstevel@tonic-gate  * CDDL HEADER END
200Sstevel@tonic-gate  */
21*6812Sraf 
220Sstevel@tonic-gate /*
23*6812Sraf  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
240Sstevel@tonic-gate  * Use is subject to license terms.
250Sstevel@tonic-gate  */
260Sstevel@tonic-gate 
270Sstevel@tonic-gate /*	Copyright (c) 1988 AT&T	*/
280Sstevel@tonic-gate /*	  All Rights Reserved  	*/
290Sstevel@tonic-gate 
30*6812Sraf #pragma ident	"%Z%%M%	%I%	%E% SMI"
310Sstevel@tonic-gate 
32*6812Sraf #include "lint.h"
330Sstevel@tonic-gate #include "file64.h"
340Sstevel@tonic-gate #include "mtlib.h"
350Sstevel@tonic-gate #include <sys/types.h>
360Sstevel@tonic-gate #include <stdio.h>
370Sstevel@tonic-gate #include <thread.h>
380Sstevel@tonic-gate #include <synch.h>
390Sstevel@tonic-gate #include "stdiom.h"
400Sstevel@tonic-gate 
410Sstevel@tonic-gate int _ungetc_unlocked(int c, FILE *iop);
420Sstevel@tonic-gate 
430Sstevel@tonic-gate int
ungetc(int c,FILE * iop)440Sstevel@tonic-gate ungetc(int c, FILE *iop)
450Sstevel@tonic-gate {
460Sstevel@tonic-gate 	FLOCKRETURN(iop, _ungetc_unlocked(c, iop))
470Sstevel@tonic-gate }
480Sstevel@tonic-gate 
490Sstevel@tonic-gate /*
500Sstevel@tonic-gate  * Called internally by the library (instead of the safe "ungetc") when
510Sstevel@tonic-gate  * iop->_lock is already held at a higher level - required since we do not
520Sstevel@tonic-gate  * have recursive locks.
530Sstevel@tonic-gate  */
540Sstevel@tonic-gate int
_ungetc_unlocked(int c,FILE * iop)550Sstevel@tonic-gate _ungetc_unlocked(int c, FILE *iop)
560Sstevel@tonic-gate {
570Sstevel@tonic-gate 	if (c == EOF)
580Sstevel@tonic-gate 		return (EOF);
590Sstevel@tonic-gate 	if (iop->_ptr <= iop->_base) {
600Sstevel@tonic-gate 		if (iop->_base == 0) {
610Sstevel@tonic-gate 			if (_findbuf(iop) == 0)
620Sstevel@tonic-gate 				return (EOF);
630Sstevel@tonic-gate 		} else if (iop->_ptr <= iop->_base - PUSHBACK)
640Sstevel@tonic-gate 			return (EOF);
650Sstevel@tonic-gate 	}
660Sstevel@tonic-gate 	if ((iop->_flag & _IOREAD) == 0) /* basically a no-op on write stream */
670Sstevel@tonic-gate 		++iop->_ptr;
680Sstevel@tonic-gate 	if (*--iop->_ptr != (unsigned char) c)
690Sstevel@tonic-gate 		*iop->_ptr = (unsigned char) c;  /* was *--iop->_ptr = c; */
700Sstevel@tonic-gate 	++iop->_cnt;
710Sstevel@tonic-gate 	iop->_flag &= ~_IOEOF;
720Sstevel@tonic-gate 	return (c);
730Sstevel@tonic-gate }
74