xref: /freebsd/lib/libc/locale/wcsftime.c (revision cd0d51baaa4509a1db83251a601d34404d20c990)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2002 Tim J. Robbins
5  * All rights reserved.
6  *
7  * Copyright (c) 2011 The FreeBSD Foundation
8  * All rights reserved.
9  * Portions of this software were developed by David Chisnall
10  * under sponsorship from the FreeBSD Foundation.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 #include <errno.h>
38 #include <limits.h>
39 #include <stdlib.h>
40 #include <time.h>
41 #include <wchar.h>
42 #include "xlocale_private.h"
43 
44 /*
45  * Convert date and time to a wide-character string.
46  *
47  * This is the wide-character counterpart of strftime(). So that we do not
48  * have to duplicate the code of strftime(), we convert the format string to
49  * multibyte, call strftime(), then convert the result back into wide
50  * characters.
51  *
52  * This technique loses in the presence of stateful multibyte encoding if any
53  * of the conversions in the format string change conversion state. When
54  * stateful encoding is implemented, we will need to reset the state between
55  * format specifications in the format string.
56  */
57 size_t
58 wcsftime_l(wchar_t * __restrict wcs, size_t maxsize,
59 	const wchar_t * __restrict format, const struct tm * __restrict timeptr,
60 	locale_t locale)
61 {
62 	static const mbstate_t initial;
63 	mbstate_t mbs;
64 	char *dst, *sformat;
65 	const char *dstp;
66 	const wchar_t *formatp;
67 	size_t n, sflen;
68 	int sverrno;
69 	FIX_LOCALE(locale);
70 
71 	sformat = dst = NULL;
72 
73 	/*
74 	 * Convert the supplied format string to a multibyte representation
75 	 * for strftime(), which only handles single-byte characters.
76 	 */
77 	mbs = initial;
78 	formatp = format;
79 	sflen = wcsrtombs_l(NULL, &formatp, 0, &mbs, locale);
80 	if (sflen == (size_t)-1)
81 		goto error;
82 	if ((sformat = malloc(sflen + 1)) == NULL)
83 		goto error;
84 	mbs = initial;
85 	wcsrtombs_l(sformat, &formatp, sflen + 1, &mbs, locale);
86 
87 	/*
88 	 * Allocate memory for longest multibyte sequence that will fit
89 	 * into the caller's buffer and call strftime() to fill it.
90 	 * Then, copy and convert the result back into wide characters in
91 	 * the caller's buffer.
92 	 */
93 	if (SIZE_T_MAX / MB_CUR_MAX <= maxsize) {
94 		/* maxsize is prepostorously large - avoid int. overflow. */
95 		errno = EINVAL;
96 		goto error;
97 	}
98 	if ((dst = malloc(maxsize * MB_CUR_MAX)) == NULL)
99 		goto error;
100 	if (strftime_l(dst, maxsize, sformat, timeptr, locale) == 0)
101 		goto error;
102 	dstp = dst;
103 	mbs = initial;
104 	n = mbsrtowcs_l(wcs, &dstp, maxsize, &mbs, locale);
105 	if (n == (size_t)-2 || n == (size_t)-1 || dstp != NULL)
106 		goto error;
107 
108 	free(sformat);
109 	free(dst);
110 	return (n);
111 
112 error:
113 	sverrno = errno;
114 	free(sformat);
115 	free(dst);
116 	errno = sverrno;
117 	return (0);
118 }
119 size_t
120 wcsftime(wchar_t * __restrict wcs, size_t maxsize,
121 	const wchar_t * __restrict format, const struct tm * __restrict timeptr)
122 {
123 	return wcsftime_l(wcs, maxsize, format, timeptr, __get_locale());
124 }
125