lib/wcsxfrm-impl.h

   1 /* Transform wide string for comparison using the current locale.
   2    Copyright (C) 2011-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2011.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation, either version 3 of the
   8    License, or (at your option) any later version.
   9
  10    This file 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 Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser 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           free (mbs2);
  59         return 0;
  60       }
  61
  62     if (result < n)
  63       {
  64         /* Convert the result by mapping char[] -> wchar_t[].
  65            Since strcmp() compares the elements as 'unsigned char' values,
  66            whereas wcscmp() compares the elements as 'wchar_t' values, we need
  67            to map 1 'unsigned char' to 1 'wchar_t'.  (We could also map 2
  68            consecutive 'unsigned char' values to 1 'wchar_t' value, but this is
  69            not needed.  */
  70         wchar_t *wcp = s1 + n;
  71         char *cp = (char *)s1 + n;
  72
  73         while (wcp > s1)
  74           *--wcp = (wchar_t) (unsigned char) *--cp;
  75       }
  76
  77     if (mbs2 != mbbuf2)
  78       free (mbs2);
  79
  80     /* No error.  */
  81     errno = saved_errno;
  82     return result;
  83   }
  84
  85  out_of_memory:
  86   errno = ENOMEM;
  87   return 0;
  88
  89  failed:
  90   errno = EILSEQ;
  91   return 0;
  92 }