lib/wcsxfrm-impl.h

   1 /* Transform wide string for comparison using the current locale.
   2    Copyright (C) 2011-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2011.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 size_t
  19 wcsxfrm (wchar_t *s1, const wchar_t *s2, size_t n)
  20 {
  21   char mbbuf2[1024];
  22   char *mbs2;
  23
  24   {
  25     int saved_errno = errno;
  26     size_t result;
  27
  28     /* Convert s2 to a multibyte string, trying to avoid malloc().  */
  29     {
  30       size_t ret;
  31
  32       ret = wcstombs (mbbuf2, s2, sizeof (mbbuf2));
  33       if (ret == (size_t)-1)
  34         goto failed;
  35       if (ret < sizeof (mbbuf2))
  36         mbs2 = mbbuf2;
  37       else
  38         {
  39           size_t need = wcstombs (NULL, s2, 0);
  40           if (need == (size_t)-1)
  41             goto failed;
  42           mbs2 = (char *) malloc (need + 1);
  43           if (mbs2 == NULL)
  44             goto out_of_memory;
  45           ret = wcstombs (mbs2, s2, need + 1);
  46           if (ret != need)
  47             abort ();
  48         }
  49     }
  50
  51     /* Transform the multibyte string.  */
  52     errno = 0;
  53     result = strxfrm ((char *)s1, mbs2, n);
  54     if (errno != 0)
  55       {
  56         /* An error occurred.  */
  57         if (mbs2 != mbbuf2)
  58           {
  59             saved_errno = errno;
  60             free (mbs2);
  61             errno = saved_errno;
  62           }
  63         return 0;
  64       }
  65
  66     if (result < n)
  67       {
  68         /* Convert the result by mapping char[] -> wchar_t[].
  69            Since strcmp() compares the elements as 'unsigned char' values,
  70            whereas wcscmp() compares the elements as 'wchar_t' values, we need
  71            to map 1 'unsigned char' to 1 'wchar_t'.  (We could also map 2
  72            consecutive 'unsigned char' values to 1 'wchar_t' value, but this is
  73            not needed.  */
  74         wchar_t *wcp = s1 + n;
  75         char *cp = (char *)s1 + n;
  76
  77         while (wcp > s1)
  78           *--wcp = (wchar_t) (unsigned char) *--cp;
  79       }
  80
  81     if (mbs2 != mbbuf2)
  82       free (mbs2);
  83
  84     /* No error.  */
  85     errno = saved_errno;
  86     return result;
  87   }
  88
  89  out_of_memory:
  90   errno = ENOMEM;
  91   return 0;
  92
  93  failed:
  94   errno = EILSEQ;
  95   return 0;
  96 }