1/* Locale-specific memory comparison.
2   Copyright (C) 1999, 2002, 2003, 2004 Free Software Foundation, Inc.
3
4   This program is free software; you can redistribute it and/or modify
5   it under the terms of the GNU General Public License as published by
6   the Free Software Foundation; either version 2, or (at your option)
7   any later version.
8
9   This program is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12   GNU General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this program; if not, write to the Free Software Foundation,
16   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
17
18/* Contributed by Paul Eggert <eggert@twinsun.com>.  */
19
20#ifdef HAVE_CONFIG_H
21# include <config.h>
22#endif
23
24#include "memcoll.h"
25
26#include <errno.h>
27#include <string.h>
28
29/* Compare S1 (with length S1LEN) and S2 (with length S2LEN) according
30   to the LC_COLLATE locale.  S1 and S2 do not overlap, and are not
31   adjacent.  Perhaps temporarily modify the bytes after S1 and S2,
32   but restore their original contents before returning.  Set errno to an
33   error number if there is an error, and to zero otherwise.  */
34int
35memcoll (char *s1, size_t s1len, char *s2, size_t s2len)
36{
37  int diff;
38
39#if HAVE_STRCOLL
40
41  char n1 = s1[s1len];
42  char n2 = s2[s2len];
43
44  s1[s1len++] = '\0';
45  s2[s2len++] = '\0';
46
47  while (! (errno = 0, (diff = strcoll (s1, s2)) || errno))
48    {
49      /* strcoll found no difference, but perhaps it was fooled by NUL
50	 characters in the data.  Work around this problem by advancing
51	 past the NUL chars.  */
52      size_t size1 = strlen (s1) + 1;
53      size_t size2 = strlen (s2) + 1;
54      s1 += size1;
55      s2 += size2;
56      s1len -= size1;
57      s2len -= size2;
58
59      if (s1len == 0)
60	{
61	  if (s2len != 0)
62	    diff = -1;
63	  break;
64	}
65      else if (s2len == 0)
66	{
67	  diff = 1;
68	  break;
69	}
70    }
71
72  s1[s1len - 1] = n1;
73  s2[s2len - 1] = n2;
74
75#else
76
77  diff = memcmp (s1, s2, s1len < s2len ? s1len : s2len);
78  if (! diff)
79    diff = s1len < s2len ? -1 : s1len != s2len;
80  errno = 0;
81
82#endif
83
84  return diff;
85}
86