1// SPDX-License-Identifier: GPL-2.0
2/*
3 *
4 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
5 *
6 */
7
8#include <linux/kernel.h>
9#include <linux/types.h>
10
11#include "ntfs_fs.h"
12
13static inline u16 upcase_unicode_char(const u16 *upcase, u16 chr)
14{
15	if (chr < 'a')
16		return chr;
17
18	if (chr <= 'z')
19		return chr - ('a' - 'A');
20
21	return upcase[chr];
22}
23
24/*
25 * ntfs_cmp_names
26 *
27 * Thanks Kari Argillander <kari.argillander@gmail.com> for idea and implementation 'bothcase'
28 *
29 * Straight way to compare names:
30 * - Case insensitive
31 * - If name equals and 'bothcases' then
32 * - Case sensitive
33 * 'Straight way' code scans input names twice in worst case.
34 * Optimized code scans input names only once.
35 */
36int ntfs_cmp_names(const __le16 *s1, size_t l1, const __le16 *s2, size_t l2,
37		   const u16 *upcase, bool bothcase)
38{
39	int diff1 = 0;
40	int diff2;
41	size_t len = min(l1, l2);
42
43	if (!bothcase && upcase)
44		goto case_insentive;
45
46	for (; len; s1++, s2++, len--) {
47		diff1 = le16_to_cpu(*s1) - le16_to_cpu(*s2);
48		if (diff1) {
49			if (bothcase && upcase)
50				goto case_insentive;
51
52			return diff1;
53		}
54	}
55	return l1 - l2;
56
57case_insentive:
58	for (; len; s1++, s2++, len--) {
59		diff2 = upcase_unicode_char(upcase, le16_to_cpu(*s1)) -
60			upcase_unicode_char(upcase, le16_to_cpu(*s2));
61		if (diff2)
62			return diff2;
63	}
64
65	diff2 = l1 - l2;
66	return diff2 ? diff2 : diff1;
67}
68
69int ntfs_cmp_names_cpu(const struct cpu_str *uni1, const struct le_str *uni2,
70		       const u16 *upcase, bool bothcase)
71{
72	const u16 *s1 = uni1->name;
73	const __le16 *s2 = uni2->name;
74	size_t l1 = uni1->len;
75	size_t l2 = uni2->len;
76	size_t len = min(l1, l2);
77	int diff1 = 0;
78	int diff2;
79
80	if (!bothcase && upcase)
81		goto case_insentive;
82
83	for (; len; s1++, s2++, len--) {
84		diff1 = *s1 - le16_to_cpu(*s2);
85		if (diff1) {
86			if (bothcase && upcase)
87				goto case_insentive;
88
89			return diff1;
90		}
91	}
92	return l1 - l2;
93
94case_insentive:
95	for (; len; s1++, s2++, len--) {
96		diff2 = upcase_unicode_char(upcase, *s1) -
97			upcase_unicode_char(upcase, le16_to_cpu(*s2));
98		if (diff2)
99			return diff2;
100	}
101
102	diff2 = l1 - l2;
103	return diff2 ? diff2 : diff1;
104}
105
106/* Helper function for ntfs_d_hash. */
107unsigned long ntfs_names_hash(const u16 *name, size_t len, const u16 *upcase,
108			      unsigned long hash)
109{
110	while (len--) {
111		unsigned int c = upcase_unicode_char(upcase, *name++);
112		hash = partial_name_hash(c, hash);
113	}
114
115	return hash;
116}
117