lib/libc/locale/wcsftime.c

   1 /*       $NetBSD: wcsftime.c,v 1.3 2007/05/21 15:32:17 tnozaki Exp $    */
   2 /*-
   3  * Copyright (c) 2002 Tim J. Robbins
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 #include <sys/cdefs.h>
  29 #if defined(LIBC_SCCS) && !defined(lint)
  30 #if 0
  31 __FBSDID("$FreeBSD: src/lib/libc/locale/wcsftime.c,v 1.4 2004/04/07 09:47:56 tjr Exp $");
  32 #else
  33 __RCSID("$NetBSD: wcsftime.c,v 1.3 2007/05/21 15:32:17 tnozaki Exp $");
  34 #endif
  35 #endif /* LIBC_SCCS and not lint */
  36
  37 #include <errno.h>
  38 #include <limits.h>
  39 #include <stdlib.h>
  40 #include <time.h>
  41 #include <wchar.h>
  42
  43 /*
  44  * Convert date and time to a wide-character string.
  45  *
  46  * This is the wide-character counterpart of strftime(). So that we do not
  47  * have to duplicate the code of strftime(), we convert the format string to
  48  * multibyte, call strftime(), then convert the result back into wide
  49  * characters.
  50  *
  51  * This technique loses in the presence of stateful multibyte encoding if any
  52  * of the conversions in the format string change conversion state. When
  53  * stateful encoding is implemented, we will need to reset the state between
  54  * format specifications in the format string.
  55  */
  56 size_t
  57 wcsftime(wchar_t *wcs, size_t maxsize,
  58     const wchar_t *format, const struct tm *timeptr)
  59 {
  60         char *dst, *dstp, *sformat;
  61         size_t n, sflen;
  62         int sverrno;
  63
  64         sformat = dst = NULL;
  65
  66         /*
  67          * Convert the supplied format string to a multibyte representation
  68          * for strftime(), which only handles single-byte characters.
  69          */
  70         sflen = wcstombs(NULL, format, 0);
  71         if (sflen == (size_t)-1)
  72                 goto error;
  73         if ((sformat = malloc(sflen + 1)) == NULL)
  74                 goto error;
  75         wcstombs(sformat, format, sflen + 1);
  76
  77         /*
  78          * Allocate memory for longest multibyte sequence that will fit
  79          * into the caller's buffer and call strftime() to fill it.
  80          * Then, copy and convert the result back into wide characters in
  81          * the caller's buffer.
  82          */
  83         if (SIZE_T_MAX / MB_CUR_MAX <= maxsize) {
  84                 /* maxsize is preposterously large - avoid int. overflow. */
  85                 errno = EINVAL;
  86                 goto error;
  87         }
  88         dst = malloc(maxsize * MB_CUR_MAX);
  89         if (dst == NULL)
  90                 goto error;
  91         if (strftime(dst, maxsize, sformat, timeptr) == 0)
  92                 goto error;
  93         dstp = dst;
  94         n = mbstowcs(wcs, dstp, maxsize);
  95         if (n == (size_t)-2 || n == (size_t)-1)
  96                 goto error;
  97
  98         free(sformat);
  99         free(dst);
 100         return n;
 101
 102 error:
 103         sverrno = errno;
 104         free(sformat);
 105         free(dst);
 106         errno = sverrno;
 107         return 0;
 108 }