xref: /freebsd/lib/libc/stdio/fgetwc.c (revision 0b7bc80226a5e70af58cce04b29957d71786e835)
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 "namespace.h"
31 #include <errno.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <wchar.h>
35 #include "un-namespace.h"
36 #include "libc_private.h"
37 #include "local.h"
38 
39 static __inline wint_t	__fgetwc_nbf(FILE *);
40 
41 wint_t
42 fgetwc(FILE *fp)
43 {
44 	wint_t wc;
45 
46 	FLOCKFILE(fp);
47 	ORIENT(fp, 1);
48 	if (MB_CUR_MAX == 1) {
49 		/*
50 		 * Assume we're using a single-byte locale. A safer test
51 		 * might be to check _CurrentRuneLocale->encoding.
52 		 */
53 		wc = (wint_t)__sgetc(fp);
54 	} else
55 		wc = __fgetwc_nbf(fp);
56 	FUNLOCKFILE(fp);
57 
58 	return (wc);
59 }
60 
61 static __inline wint_t
62 __fgetwc_nbf(FILE *fp)
63 {
64 	char buf[MB_LEN_MAX];
65 	mbstate_t mbs;
66 	size_t n, nconv;
67 	int c;
68 	wchar_t wc;
69 
70 	n = 0;
71 	while (n < MB_CUR_MAX) {
72 		if ((c = __sgetc(fp)) == EOF) {
73 			if (n == 0)
74 				return (WEOF);
75 			break;
76 		}
77 		buf[n++] = (char)c;
78 		memset(&mbs, 0, sizeof(mbs));
79 		nconv = mbrtowc(&wc, buf, n, &mbs);
80 		if (nconv == n)
81 			return (wc);
82 		else if (nconv == 0)
83 			return (L'\0');
84 		else if (nconv == (size_t)-1)
85 			break;
86 	}
87 
88 	FUNLOCKFILE(fp);
89 	while (n-- != 0)
90 		ungetc((unsigned char)buf[n], fp);
91 	FLOCKFILE(fp);
92 	errno = EILSEQ;
93 	return (WEOF);
94 }
95