xref: /illumos-gate/usr/src/lib/libc/port/locale/wcsftime.c (revision 8d0c3d29bb99f6521f2dc5058a7e4debebad7899)
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  * Copyright 2010 Nexenta Systems, Inc.  All rights reserved.
28  * Use is subject to license terms.
29  */
30 
31 #include "lint.h"
32 #include "mse_int.h"
33 #include <errno.h>
34 #include <limits.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <time.h>
38 #include <wchar.h>
39 #include <alloca.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  * Note carefully that prior to xpg5, the format was char *, not wchar_t.
55  */
56 
57 /*
58  * Hmmm this is probably a bit backwards.  As we are converting to single
59  * byte formats, perhaps we should not be doing a redundant conversion.
60  * Something to look at for the future.
61  */
62 
63 size_t
64 __wcsftime_xpg5(wchar_t *wcs, size_t maxsize, const wchar_t *format,
65     const struct tm *timeptr)
66 {
67 	static const mbstate_t initial = { 0 };
68 	mbstate_t mbs;
69 	char *dst, *sformat;
70 	const char *dstp;
71 	const wchar_t *formatp;
72 	size_t n, sflen;
73 	int sverrno;
74 
75 	sformat = dst = NULL;
76 
77 	/*
78 	 * Convert the supplied format string to a multibyte representation
79 	 * for strftime(), which only handles single-byte characters.
80 	 */
81 	mbs = initial;
82 	formatp = format;
83 	sflen = wcsrtombs(NULL, &formatp, 0, &mbs);
84 	if (sflen == (size_t)-1)
85 		goto error;
86 	if ((sformat = malloc(sflen + 1)) == NULL)
87 		goto error;
88 	mbs = initial;
89 	(void) wcsrtombs(sformat, &formatp, sflen + 1, &mbs);
90 
91 	/*
92 	 * Allocate memory for longest multibyte sequence that will fit
93 	 * into the caller's buffer and call strftime() to fill it.
94 	 * Then, copy and convert the result back into wide characters in
95 	 * the caller's buffer.
96 	 */
97 	if (LONG_MAX / MB_CUR_MAX <= maxsize) {
98 		/* maxsize is prepostorously large - avoid int. overflow. */
99 		errno = EINVAL;
100 		goto error;
101 	}
102 	if ((dst = malloc(maxsize * MB_CUR_MAX)) == NULL)
103 		goto error;
104 	if (strftime(dst, maxsize, sformat, timeptr) == 0)
105 		goto error;
106 	dstp = dst;
107 	mbs = initial;
108 	n = mbsrtowcs(wcs, &dstp, maxsize, &mbs);
109 	if (n == (size_t)-2 || n == (size_t)-1 || dstp != NULL)
110 		goto error;
111 
112 	free(sformat);
113 	free(dst);
114 	return (n);
115 
116 error:
117 	sverrno = errno;
118 	free(sformat);
119 	free(dst);
120 	errno = sverrno;
121 	return (0);
122 }
123 
124 size_t
125 wcsftime(wchar_t *wcs, size_t maxsize, const char *format,
126     const struct tm *timeptr)
127 {
128 	int	len;
129 	wchar_t	*wfmt;
130 
131 	/* Convert the format (mb string) to wide char array */
132 	len = strlen(format) + 1;
133 	wfmt = alloca(sizeof (wchar_t) * len);
134 	if (mbstowcs(wfmt, format, len) == (size_t)-1) {
135 		return (0);
136 	}
137 	return (__wcsftime_xpg5(wcs, maxsize, wfmt, timeptr));
138 }
139