xref: /freebsd/lib/libc/locale/wcsftime.c (revision ae1f3df43466466a21c7da0df93ecb58a3e53d74)
1 /*-
2  * Copyright (c) 2002 Tim J. Robbins
3  * All rights reserved.
4  *
5  * Copyright (c) 2011 The FreeBSD Foundation
6  * All rights reserved.
7  * Portions of this software were developed by David Chisnall
8  * under sponsorship from the FreeBSD Foundation.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include <errno.h>
36 #include <limits.h>
37 #include <stdlib.h>
38 #include <time.h>
39 #include <wchar.h>
40 #include "xlocale_private.h"
41 
42 /*
43  * Convert date and time to a wide-character string.
44  *
45  * This is the wide-character counterpart of strftime(). So that we do not
46  * have to duplicate the code of strftime(), we convert the format string to
47  * multibyte, call strftime(), then convert the result back into wide
48  * characters.
49  *
50  * This technique loses in the presence of stateful multibyte encoding if any
51  * of the conversions in the format string change conversion state. When
52  * stateful encoding is implemented, we will need to reset the state between
53  * format specifications in the format string.
54  */
55 size_t
56 wcsftime_l(wchar_t * __restrict wcs, size_t maxsize,
57 	const wchar_t * __restrict format, const struct tm * __restrict timeptr,
58 	locale_t locale)
59 {
60 	static const mbstate_t initial;
61 	mbstate_t mbs;
62 	char *dst, *sformat;
63 	const char *dstp;
64 	const wchar_t *formatp;
65 	size_t n, sflen;
66 	int sverrno;
67 	FIX_LOCALE(locale);
68 
69 	sformat = dst = NULL;
70 
71 	/*
72 	 * Convert the supplied format string to a multibyte representation
73 	 * for strftime(), which only handles single-byte characters.
74 	 */
75 	mbs = initial;
76 	formatp = format;
77 	sflen = wcsrtombs_l(NULL, &formatp, 0, &mbs, locale);
78 	if (sflen == (size_t)-1)
79 		goto error;
80 	if ((sformat = malloc(sflen + 1)) == NULL)
81 		goto error;
82 	mbs = initial;
83 	wcsrtombs_l(sformat, &formatp, sflen + 1, &mbs, locale);
84 
85 	/*
86 	 * Allocate memory for longest multibyte sequence that will fit
87 	 * into the caller's buffer and call strftime() to fill it.
88 	 * Then, copy and convert the result back into wide characters in
89 	 * the caller's buffer.
90 	 */
91 	if (SIZE_T_MAX / MB_CUR_MAX <= maxsize) {
92 		/* maxsize is prepostorously large - avoid int. overflow. */
93 		errno = EINVAL;
94 		goto error;
95 	}
96 	if ((dst = malloc(maxsize * MB_CUR_MAX)) == NULL)
97 		goto error;
98 	if (strftime_l(dst, maxsize, sformat, timeptr, locale) == 0)
99 		goto error;
100 	dstp = dst;
101 	mbs = initial;
102 	n = mbsrtowcs_l(wcs, &dstp, maxsize, &mbs, locale);
103 	if (n == (size_t)-2 || n == (size_t)-1 || dstp != NULL)
104 		goto error;
105 
106 	free(sformat);
107 	free(dst);
108 	return (n);
109 
110 error:
111 	sverrno = errno;
112 	free(sformat);
113 	free(dst);
114 	errno = sverrno;
115 	return (0);
116 }
117 size_t
118 wcsftime(wchar_t * __restrict wcs, size_t maxsize,
119 	const wchar_t * __restrict format, const struct tm * __restrict timeptr)
120 {
121 	return wcsftime_l(wcs, maxsize, format, timeptr, __get_locale());
122 }
123