lib/libc/locale/wcsftime.c

   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  * $FreeBSD: src/lib/libc/locale/wcsftime.c,v 1.4 2004/04/07 09:47:56 tjr Exp $
  27  * $DragonFly: src/lib/libc/locale/wcsftime.c,v 1.1 2005/08/10 13:42:28 joerg Exp $
  28  */
  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  */
  49 size_t
  50 wcsftime(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         const wchar_t *formatp;
  57         size_t n, sflen;
  58         int sverrno;
  59
  60         sformat = dst = NULL;
  61
  62         /*
  63          * Convert the supplied format string to a multibyte representation
  64          * for strftime(), which only handles single-byte characters.
  65          */
  66         mbs = initial;
  67         formatp = format;
  68         sflen = wcsrtombs(NULL, &formatp, 0, &mbs);
  69         if (sflen == (size_t)-1)
  70                 goto error;
  71         if ((sformat = malloc(sflen + 1)) == NULL)
  72                 goto error;
  73         mbs = initial;
  74         wcsrtombs(sformat, &formatp, sflen + 1, &mbs);
  75
  76         /*
  77          * Allocate memory for longest multibyte sequence that will fit
  78          * into the caller's buffer and call strftime() to fill it.
  79          * Then, copy and convert the result back into wide characters in
  80          * the caller's buffer.
  81          */
  82         if (SIZE_T_MAX / MB_CUR_MAX <= maxsize) {
  83                 /* maxsize is prepostorously large - avoid int. overflow. */
  84                 errno = EINVAL;
  85                 goto error;
  86         }
  87         if ((dst = malloc(maxsize * MB_CUR_MAX)) == NULL)
  88                 goto error;
  89         if (strftime(dst, maxsize, sformat, timeptr) == 0)
  90                 goto error;
  91         dstp = dst;
  92         mbs = initial;
  93         n = mbsrtowcs(wcs, (const char **)&dstp, maxsize, &mbs);
  94         if (n == (size_t)-2 || n == (size_t)-1 || dstp != NULL)
  95                 goto error;
  96
  97         free(sformat);
  98         free(dst);
  99         return (n);
 100
 101 error:
 102         sverrno = errno;
 103         free(sformat);
 104         free(dst);
 105         errno = sverrno;
 106         return (0);
 107 }