xref: /freebsd/lib/libc/locale/mbrtowc.c (revision 4b2eaea43fec8e8792be611dea204071a10b655a)
1 /*-
2  * Copyright (c) 2002 Tim J. Robbins.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <errno.h>
31 #include <rune.h>
32 #include <stdlib.h>
33 #include <wchar.h>
34 
35 size_t
36 mbrtowc(wchar_t * __restrict pwc, const char * __restrict s, size_t n,
37     mbstate_t * __restrict ps __unused)
38 {
39         const char *e;
40         rune_t r;
41 
42 	if (s == NULL) {
43 		pwc = NULL;
44 		s = "";
45 		n = 1;
46 	}
47 
48 	if ((r = sgetrune(s, n, &e)) == _INVALID_RUNE) {
49 		/*
50 		 * The design of sgetrune() doesn't give us any way to tell
51 		 * between incomplete and invalid multibyte sequences.
52 		 */
53 
54 		if (n >= (size_t)MB_CUR_MAX) {
55 			/*
56 			 * If we have been supplied with at least MB_CUR_MAX
57 			 * bytes and still cannot find a valid character, the
58 			 * data must be invalid.
59 			 */
60 			errno = EILSEQ;
61 			return ((size_t)-1);
62 		}
63 
64 		/*
65 		 * .. otherwise, it's an incomplete character or an invalid
66 		 * character we cannot detect yet.
67 		 */
68 		return ((size_t)-2);
69 	}
70 
71 	if (pwc != NULL)
72 		*pwc = (wchar_t)r;
73 
74 	return (r != 0 ? (size_t)(e - s) : 0);
75 }
76