linux/fs/ntfs/collate.c
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   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
  26static 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
  44static 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        // FIXME:  We don't really want to bug here.
  53        BUG_ON(data1_len != data2_len);
  54        BUG_ON(data1_len != 4);
  55        d1 = le32_to_cpup(data1);
  56        d2 = le32_to_cpup(data2);
  57        if (d1 < d2)
  58                rc = -1;
  59        else {
  60                if (d1 == d2)
  61                        rc = 0;
  62                else
  63                        rc = 1;
  64        }
  65        ntfs_debug("Done, returning %i", rc);
  66        return rc;
  67}
  68
  69typedef int (*ntfs_collate_func_t)(ntfs_volume *, const void *, const int,
  70                const void *, const int);
  71
  72static ntfs_collate_func_t ntfs_do_collate0x0[3] = {
  73        ntfs_collate_binary,
  74        NULL/*ntfs_collate_file_name*/,
  75        NULL/*ntfs_collate_unicode_string*/,
  76};
  77
  78static ntfs_collate_func_t ntfs_do_collate0x1[4] = {
  79        ntfs_collate_ntofs_ulong,
  80        NULL/*ntfs_collate_ntofs_sid*/,
  81        NULL/*ntfs_collate_ntofs_security_hash*/,
  82        NULL/*ntfs_collate_ntofs_ulongs*/,
  83};
  84
  85/**
  86 * ntfs_collate - collate two data items using a specified collation rule
  87 * @vol:        ntfs volume to which the data items belong
  88 * @cr:         collation rule to use when comparing the items
  89 * @data1:      first data item to collate
  90 * @data1_len:  length in bytes of @data1
  91 * @data2:      second data item to collate
  92 * @data2_len:  length in bytes of @data2
  93 *
  94 * Collate the two data items @data1 and @data2 using the collation rule @cr
  95 * and return -1, 0, ir 1 if @data1 is found, respectively, to collate before,
  96 * to match, or to collate after @data2.
  97 *
  98 * For speed we use the collation rule @cr as an index into two tables of
  99 * function pointers to call the appropriate collation function.
 100 */
 101int ntfs_collate(ntfs_volume *vol, COLLATION_RULE cr,
 102                const void *data1, const int data1_len,
 103                const void *data2, const int data2_len) {
 104        int i;
 105
 106        ntfs_debug("Entering.");
 107        /*
 108         * FIXME:  At the moment we only support COLLATION_BINARY and
 109         * COLLATION_NTOFS_ULONG, so we BUG() for everything else for now.
 110         */
 111        BUG_ON(cr != COLLATION_BINARY && cr != COLLATION_NTOFS_ULONG);
 112        i = le32_to_cpu(cr);
 113        BUG_ON(i < 0);
 114        if (i <= 0x02)
 115                return ntfs_do_collate0x0[i](vol, data1, data1_len,
 116                                data2, data2_len);
 117        BUG_ON(i < 0x10);
 118        i -= 0x10;
 119        if (likely(i <= 3))
 120                return ntfs_do_collate0x1[i](vol, data1, data1_len,
 121                                data2, data2_len);
 122        BUG();
 123        return 0;
 124}
 125
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