xref: /freebsd/lib/libc/locale/wcsftime.c (revision 5f4c09dd85bff675e0ca63c55ea3c517e0fddfcc)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2002 Tim J. Robbins
5  * All rights reserved.
6  *
7  * Copyright (c) 2011 The FreeBSD Foundation
8  *
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 <errno.h>
35 #include <limits.h>
36 #include <stdlib.h>
37 #include <time.h>
38 #include <wchar.h>
39 #include "xlocale_private.h"
40 
41 /*
42  * Convert date and time to a wide-character string.
43  *
44  * This is the wide-character counterpart of strftime(). So that we do not
45  * have to duplicate the code of strftime(), we convert the format string to
46  * multibyte, call strftime(), then convert the result back into wide
47  * characters.
48  *
49  * This technique loses in the presence of stateful multibyte encoding if any
50  * of the conversions in the format string change conversion state. When
51  * stateful encoding is implemented, we will need to reset the state between
52  * format specifications in the format string.
53  */
54 size_t
55 wcsftime_l(wchar_t * __restrict wcs, size_t maxsize,
56 	const wchar_t * __restrict format, const struct tm * __restrict timeptr,
57 	locale_t locale)
58 {
59 	static const mbstate_t initial;
60 	mbstate_t mbs;
61 	char *dst, *sformat;
62 	const char *dstp;
63 	const wchar_t *formatp;
64 	size_t n, sflen;
65 	int sverrno;
66 	FIX_LOCALE(locale);
67 
68 	sformat = dst = NULL;
69 
70 	/*
71 	 * Convert the supplied format string to a multibyte representation
72 	 * for strftime(), which only handles single-byte characters.
73 	 */
74 	mbs = initial;
75 	formatp = format;
76 	sflen = wcsrtombs_l(NULL, &formatp, 0, &mbs, locale);
77 	if (sflen == (size_t)-1)
78 		goto error;
79 	if ((sformat = malloc(sflen + 1)) == NULL)
80 		goto error;
81 	mbs = initial;
82 	wcsrtombs_l(sformat, &formatp, sflen + 1, &mbs, locale);
83 
84 	/*
85 	 * Allocate memory for longest multibyte sequence that will fit
86 	 * into the caller's buffer and call strftime() to fill it.
87 	 * Then, copy and convert the result back into wide characters in
88 	 * the caller's buffer.
89 	 */
90 	if (SIZE_T_MAX / MB_CUR_MAX <= maxsize) {
91 		/* maxsize is prepostorously large - avoid int. overflow. */
92 		errno = EINVAL;
93 		goto error;
94 	}
95 	if ((dst = malloc(maxsize * MB_CUR_MAX)) == NULL)
96 		goto error;
97 	if (strftime_l(dst, maxsize, sformat, timeptr, locale) == 0)
98 		goto error;
99 	dstp = dst;
100 	mbs = initial;
101 	n = mbsrtowcs_l(wcs, &dstp, maxsize, &mbs, locale);
102 	if (n == (size_t)-2 || n == (size_t)-1 || dstp != NULL)
103 		goto error;
104 
105 	free(sformat);
106 	free(dst);
107 	return (n);
108 
109 error:
110 	sverrno = errno;
111 	free(sformat);
112 	free(dst);
113 	errno = sverrno;
114 	return (0);
115 }
116 size_t
117 wcsftime(wchar_t * __restrict wcs, size_t maxsize,
118 	const wchar_t * __restrict format, const struct tm * __restrict timeptr)
119 {
120 	return wcsftime_l(wcs, maxsize, format, timeptr, __get_locale());
121 }
122