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