release/src-rt-6.x.4708/linux/linux-2.6.36/fs/ntfs/collate.c

   1 /*
   2  * collate.c - NTFS kernel collation handling.  Part of the Linux-NTFS project.
   3  *
   4  * Copyright (c) 2004 Anton Altaparmakov
   5  *
   6  * This program/include file is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as published
   8  * by the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program/include file is distributed in the hope that it will be
  12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program (in the main directory of the Linux-NTFS
  18  * distribution in the file COPYING); if not, write to the Free Software
  19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #include "collate.h"
  23 #include "debug.h"
  24 #include "ntfs.h"
  25
  26 static int ntfs_collate_binary(ntfs_volume *vol,
  27                 const void *data1, const int data1_len,
  28                 const void *data2, const int data2_len)
  29 {
  30         int rc;
  31
  32         ntfs_debug("Entering.");
  33         rc = memcmp(data1, data2, min(data1_len, data2_len));
  34         if (!rc && (data1_len != data2_len)) {
  35                 if (data1_len < data2_len)
  36                         rc = -1;
  37                 else
  38                         rc = 1;
  39         }
  40         ntfs_debug("Done, returning %i", rc);
  41         return rc;
  42 }
  43
  44 static int ntfs_collate_ntofs_ulong(ntfs_volume *vol,
  45                 const void *data1, const int data1_len,
  46                 const void *data2, const int data2_len)
  47 {
  48         int rc;
  49         u32 d1, d2;
  50
  51         ntfs_debug("Entering.");
  52         BUG_ON(data1_len != data2_len);
  53         BUG_ON(data1_len != 4);
  54         d1 = le32_to_cpup(data1);
  55         d2 = le32_to_cpup(data2);
  56         if (d1 < d2)
  57                 rc = -1;
  58         else {
  59                 if (d1 == d2)
  60                         rc = 0;
  61                 else
  62                         rc = 1;
  63         }
  64         ntfs_debug("Done, returning %i", rc);
  65         return rc;
  66 }
  67
  68 typedef int (*ntfs_collate_func_t)(ntfs_volume *, const void *, const int,
  69                 const void *, const int);
  70
  71 static ntfs_collate_func_t ntfs_do_collate0x0[3] = {
  72         ntfs_collate_binary,
  73         NULL/*ntfs_collate_file_name*/,
  74         NULL/*ntfs_collate_unicode_string*/,
  75 };
  76
  77 static ntfs_collate_func_t ntfs_do_collate0x1[4] = {
  78         ntfs_collate_ntofs_ulong,
  79         NULL/*ntfs_collate_ntofs_sid*/,
  80         NULL/*ntfs_collate_ntofs_security_hash*/,
  81         NULL/*ntfs_collate_ntofs_ulongs*/,
  82 };
  83
  84 /**
  85  * ntfs_collate - collate two data items using a specified collation rule
  86  * @vol:        ntfs volume to which the data items belong
  87  * @cr:         collation rule to use when comparing the items
  88  * @data1:      first data item to collate
  89  * @data1_len:  length in bytes of @data1
  90  * @data2:      second data item to collate
  91  * @data2_len:  length in bytes of @data2
  92  *
  93  * Collate the two data items @data1 and @data2 using the collation rule @cr
  94  * and return -1, 0, ir 1 if @data1 is found, respectively, to collate before,
  95  * to match, or to collate after @data2.
  96  *
  97  * For speed we use the collation rule @cr as an index into two tables of
  98  * function pointers to call the appropriate collation function.
  99  */
 100 int ntfs_collate(ntfs_volume *vol, COLLATION_RULE cr,
 101                 const void *data1, const int data1_len,
 102                 const void *data2, const int data2_len) {
 103         int i;
 104
 105         ntfs_debug("Entering.");
 106         BUG_ON(cr != COLLATION_BINARY && cr != COLLATION_NTOFS_ULONG);
 107         i = le32_to_cpu(cr);
 108         BUG_ON(i < 0);
 109         if (i <= 0x02)
 110                 return ntfs_do_collate0x0[i](vol, data1, data1_len,
 111                                 data2, data2_len);
 112         BUG_ON(i < 0x10);
 113         i -= 0x10;
 114         if (likely(i <= 3))
 115                 return ntfs_do_collate0x1[i](vol, data1, data1_len,
 116                                 data2, data2_len);
 117         BUG();
 118         return 0;
 119 }