Root/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
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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