Line data    Source code

       1             : /* Locale-specific memory comparison.
       2             : 
       3             :    Copyright (C) 1999, 2002, 2003, 2004, 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             : /* Contributed by Paul Eggert <eggert@twinsun.com>.  */
      19             : 
      20             : #include <config.h>
      21             : 
      22             : #include "memcoll.h"
      23             : 
      24             : #include <errno.h>
      25             : #include <string.h>
      26             : 
      27             : /* Compare S1 (with length S1LEN) and S2 (with length S2LEN) according
      28             :    to the LC_COLLATE locale.  S1 and S2 do not overlap, and are not
      29             :    adjacent.  Perhaps temporarily modify the bytes after S1 and S2,
      30             :    but restore their original contents before returning.  Set errno to an
      31             :    error number if there is an error, and to zero otherwise.  */
      32             : int
      33           0 : memcoll (char *s1, size_t s1len, char *s2, size_t s2len)
      34             : {
      35             :   int diff;
      36             : 
      37             : #if HAVE_STRCOLL
      38             : 
      39             :   /* strcoll is slow on many platforms, so check for the common case
      40             :      where the arguments are bytewise equal.  Otherwise, walk through
      41             :      the buffers using strcoll on each substring.  */
      42             : 
      43           0 :   if (s1len == s2len && memcmp (s1, s2, s1len) == 0)
      44             :     {
      45           0 :       errno = 0;
      46           0 :       diff = 0;
      47             :     }
      48             :   else
      49             :     {
      50           0 :       char n1 = s1[s1len];
      51           0 :       char n2 = s2[s2len];
      52             : 
      53           0 :       s1[s1len++] = '\0';
      54           0 :       s2[s2len++] = '\0';
      55             : 
      56           0 :       while (! (errno = 0, (diff = strcoll (s1, s2)) || errno))
      57             :         {
      58             :           /* strcoll found no difference, but perhaps it was fooled by NUL
      59             :              characters in the data.  Work around this problem by advancing
      60             :              past the NUL chars.  */
      61           0 :           size_t size1 = strlen (s1) + 1;
      62           0 :           size_t size2 = strlen (s2) + 1;
      63           0 :           s1 += size1;
      64           0 :           s2 += size2;
      65           0 :           s1len -= size1;
      66           0 :           s2len -= size2;
      67             : 
      68           0 :           if (s1len == 0)
      69             :             {
      70           0 :               if (s2len != 0)
      71           0 :                 diff = -1;
      72           0 :               break;
      73             :             }
      74           0 :           else if (s2len == 0)
      75             :             {
      76           0 :               diff = 1;
      77           0 :               break;
      78             :             }
      79             :         }
      80             : 
      81           0 :       s1[s1len - 1] = n1;
      82           0 :       s2[s2len - 1] = n2;
      83             :     }
      84             : 
      85             : #else
      86             : 
      87             :   diff = memcmp (s1, s2, s1len < s2len ? s1len : s2len);
      88             :   if (! diff)
      89             :     diff = s1len < s2len ? -1 : s1len != s2len;
      90             :   errno = 0;
      91             : 
      92             : #endif
      93             : 
      94           0 :   return diff;
      95             : }