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	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
68typedef int (*ntfs_collate_func_t)(ntfs_volume *, const void *, const int,
69		const void *, const int);
70
71static 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
77static 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 */
100int 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}
120