1 /*	$OpenBSD: btowc.c,v 1.2 2012/12/05 23:20:00 deraadt Exp $ */
2 
3 /*-
4  * Copyright (c) 2002, 2003 Tim J. Robbins.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <stdio.h>
30 #include <string.h>
31 #include <wchar.h>
32 
33 wint_t
btowc(int c)34 btowc(int c)
35 {
36 	mbstate_t mbs;
37 	char cc;
38 	wchar_t wc;
39 
40 	if (c == EOF)
41 		return (WEOF);
42 	/*
43 	 * We expect mbrtowc() to return 0 or 1, hence the check for n > 1
44 	 * which detects error return values as well as "impossible" byte
45 	 * counts.
46 	 */
47 	memset(&mbs, 0, sizeof(mbs));
48 	cc = (char)c;
49 	if (mbrtowc(&wc, &cc, 1, &mbs) > 1)
50 		return (WEOF);
51 	return (wc);
52 }
53