wcsftime.c revision 127998 
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: head/lib/libc/locale/wcsftime.c 127998 2004-04-07 09:47:56Z tjr $");
29
30#include <errno.h>
31#include <limits.h>
32#include <stdlib.h>
33#include <time.h>
34#include <wchar.h>
35
36/*
37 * Convert date and time to a wide-character string.
38 *
39 * This is the wide-character counterpart of strftime(). So that we do not
40 * have to duplicate the code of strftime(), we convert the format string to
41 * multibyte, call strftime(), then convert the result back into wide
42 * characters.
43 *
44 * This technique loses in the presence of stateful multibyte encoding if any
45 * of the conversions in the format string change conversion state. When
46 * stateful encoding is implemented, we will need to reset the state between
47 * format specifications in the format string.
48 */
49size_t
50wcsftime(wchar_t * __restrict wcs, size_t maxsize,
51    const wchar_t * __restrict format, const struct tm * __restrict timeptr)
52{
53	static const mbstate_t initial;
54	mbstate_t mbs;
55	char *dst, *dstp, *sformat;
56	size_t n, sflen;
57	int sverrno;
58
59	sformat = dst = NULL;
60
61	/*
62	 * Convert the supplied format string to a multibyte representation
63	 * for strftime(), which only handles single-byte characters.
64	 */
65	mbs = initial;
66	sflen = wcsrtombs(NULL, &format, 0, &mbs);
67	if (sflen == (size_t)-1)
68		goto error;
69	if ((sformat = malloc(sflen + 1)) == NULL)
70		goto error;
71	mbs = initial;
72	wcsrtombs(sformat, &format, sflen + 1, &mbs);
73
74	/*
75	 * Allocate memory for longest multibyte sequence that will fit
76	 * into the caller's buffer and call strftime() to fill it.
77	 * Then, copy and convert the result back into wide characters in
78	 * the caller's buffer.
79	 */
80	if (SIZE_T_MAX / MB_CUR_MAX <= maxsize) {
81		/* maxsize is prepostorously large - avoid int. overflow. */
82		errno = EINVAL;
83		goto error;
84	}
85	if ((dst = malloc(maxsize * MB_CUR_MAX)) == NULL)
86		goto error;
87	if (strftime(dst, maxsize, sformat, timeptr) == 0)
88		goto error;
89	dstp = dst;
90	mbs = initial;
91	n = mbsrtowcs(wcs, (const char **)&dstp, maxsize, &mbs);
92	if (n == (size_t)-2 || n == (size_t)-1 || dstp != NULL)
93		goto error;
94
95	free(sformat);
96	free(dst);
97	return (n);
98
99error:
100	sverrno = errno;
101	free(sformat);
102	free(dst);
103	errno = sverrno;
104	return (0);
105}
106