lib/memxfrm.c

   1 /* Locale-specific memory transformation
   2
   3    Copyright (C) 2006 Free Software Foundation, Inc.
   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 <http://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Paul Eggert <eggert@cs.ucla.edu>.  */
  19
  20 #include <config.h>
  21
  22 #include "memxfrm.h"
  23
  24 #include <errno.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27
  28 /* Store into DEST (of size DESTSIZE) the text in SRC (of size SRCSIZE)
  29    transformed so that the result of memcmp on two transformed texts
  30    (with ties going to the longer text) is the same as the result of
  31    memcoll on the two texts before their transformation.  Perhaps
  32    temporarily modify the byte after SRC, but restore its original
  33    contents before returning.
  34
  35    Return the size of the resulting text, or an indeterminate value if
  36    there is an error.  Set errno to an error number if there is an
  37    error, and to zero otherwise.  DEST contains an indeterminate value
  38    if there is an error or if the resulting size is greater than
  39    DESTSIZE.  */
  40
  41 size_t
  42 memxfrm (char *restrict dest, size_t destsize,
  43          char *restrict src, size_t srcsize)
  44 {
  45 #if HAVE_STRXFRM
  46
  47   size_t di = 0;
  48   size_t si = 0;
  49   size_t result = 0;
  50
  51   char ch = src[srcsize];
  52   src[srcsize] = '\0';
  53
  54   while (si < srcsize)
  55     {
  56       size_t slen = strlen (src + si);
  57
  58       size_t result0 = result;
  59       errno = 0;
  60       result += strxfrm (dest + di, src + si, destsize - di) + 1;
  61       if (errno != 0)
  62         break;
  63       if (result <= result0)
  64         {
  65           errno = ERANGE;
  66           break;
  67         }
  68
  69       if (result == destsize + 1 && si + slen == srcsize)
  70         {
  71           /* The destination is exactly the right size, but strxfrm wants
  72              room for a trailing null.  Work around the problem with a
  73              temporary buffer.  */
  74           size_t bufsize = destsize - di + 1;
  75           char stackbuf[4000];
  76           char *buf = stackbuf;
  77           if (sizeof stackbuf < bufsize)
  78             {
  79               buf = malloc (bufsize);
  80               if (! buf)
  81                 break;
  82             }
  83           strxfrm (buf, src + si, bufsize);
  84           memcpy (dest + di, buf, destsize - di);
  85           if (sizeof stackbuf < bufsize)
  86             free (buf);
  87           errno = 0;
  88         }
  89
  90       di = (result < destsize ? result : destsize);
  91       si += slen + 1;
  92     }
  93
  94   src[srcsize] = ch;
  95   return result - (si != srcsize);
  96
  97 #else
  98
  99   if (srcsize < destsize)
 100     memcpy (dest, src, srcsize);
 101   errno = 0;
 102   return srcsize;
 103
 104 #endif
 105 }