1// SPDX-License-Identifier: GPL-2.0
2#include <linux/ucs2_string.h>
3#include <linux/module.h>
4
5/* Return the number of unicode characters in data */
6unsigned long
7ucs2_strnlen(const ucs2_char_t *s, size_t maxlength)
8{
9        unsigned long length = 0;
10
11        while (*s++ != 0 && length < maxlength)
12                length++;
13        return length;
14}
15EXPORT_SYMBOL(ucs2_strnlen);
16
17unsigned long
18ucs2_strlen(const ucs2_char_t *s)
19{
20        return ucs2_strnlen(s, ~0UL);
21}
22EXPORT_SYMBOL(ucs2_strlen);
23
24/*
25 * Return the number of bytes is the length of this string
26 * Note: this is NOT the same as the number of unicode characters
27 */
28unsigned long
29ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength)
30{
31        return ucs2_strnlen(data, maxlength/sizeof(ucs2_char_t)) * sizeof(ucs2_char_t);
32}
33EXPORT_SYMBOL(ucs2_strsize);
34
35/**
36 * ucs2_strscpy() - Copy a UCS2 string into a sized buffer.
37 *
38 * @dst: Pointer to the destination buffer where to copy the string to.
39 * @src: Pointer to the source buffer where to copy the string from.
40 * @count: Size of the destination buffer, in UCS2 (16-bit) characters.
41 *
42 * Like strscpy(), only for UCS2 strings.
43 *
44 * Copy the source string @src, or as much of it as fits, into the destination
45 * buffer @dst. The behavior is undefined if the string buffers overlap. The
46 * destination buffer @dst is always NUL-terminated, unless it's zero-sized.
47 *
48 * Return: The number of characters copied into @dst (excluding the trailing
49 * %NUL terminator) or -E2BIG if @count is 0 or @src was truncated due to the
50 * destination buffer being too small.
51 */
52ssize_t ucs2_strscpy(ucs2_char_t *dst, const ucs2_char_t *src, size_t count)
53{
54	long res;
55
56	/*
57	 * Ensure that we have a valid amount of space. We need to store at
58	 * least one NUL-character.
59	 */
60	if (count == 0 || WARN_ON_ONCE(count > INT_MAX / sizeof(*dst)))
61		return -E2BIG;
62
63	/*
64	 * Copy at most 'count' characters, return early if we find a
65	 * NUL-terminator.
66	 */
67	for (res = 0; res < count; res++) {
68		ucs2_char_t c;
69
70		c = src[res];
71		dst[res] = c;
72
73		if (!c)
74			return res;
75	}
76
77	/*
78	 * The loop above terminated without finding a NUL-terminator,
79	 * exceeding the 'count': Enforce proper NUL-termination and return
80	 * error.
81	 */
82	dst[count - 1] = 0;
83	return -E2BIG;
84}
85EXPORT_SYMBOL(ucs2_strscpy);
86
87int
88ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len)
89{
90        while (1) {
91                if (len == 0)
92                        return 0;
93                if (*a < *b)
94                        return -1;
95                if (*a > *b)
96                        return 1;
97                if (*a == 0) /* implies *b == 0 */
98                        return 0;
99                a++;
100                b++;
101                len--;
102        }
103}
104EXPORT_SYMBOL(ucs2_strncmp);
105
106unsigned long
107ucs2_utf8size(const ucs2_char_t *src)
108{
109	unsigned long i;
110	unsigned long j = 0;
111
112	for (i = 0; src[i]; i++) {
113		u16 c = src[i];
114
115		if (c >= 0x800)
116			j += 3;
117		else if (c >= 0x80)
118			j += 2;
119		else
120			j += 1;
121	}
122
123	return j;
124}
125EXPORT_SYMBOL(ucs2_utf8size);
126
127/*
128 * copy at most maxlength bytes of whole utf8 characters to dest from the
129 * ucs2 string src.
130 *
131 * The return value is the number of characters copied, not including the
132 * final NUL character.
133 */
134unsigned long
135ucs2_as_utf8(u8 *dest, const ucs2_char_t *src, unsigned long maxlength)
136{
137	unsigned int i;
138	unsigned long j = 0;
139	unsigned long limit = ucs2_strnlen(src, maxlength);
140
141	for (i = 0; maxlength && i < limit; i++) {
142		u16 c = src[i];
143
144		if (c >= 0x800) {
145			if (maxlength < 3)
146				break;
147			maxlength -= 3;
148			dest[j++] = 0xe0 | (c & 0xf000) >> 12;
149			dest[j++] = 0x80 | (c & 0x0fc0) >> 6;
150			dest[j++] = 0x80 | (c & 0x003f);
151		} else if (c >= 0x80) {
152			if (maxlength < 2)
153				break;
154			maxlength -= 2;
155			dest[j++] = 0xc0 | (c & 0x7c0) >> 6;
156			dest[j++] = 0x80 | (c & 0x03f);
157		} else {
158			maxlength -= 1;
159			dest[j++] = c & 0x7f;
160		}
161	}
162	if (maxlength)
163		dest[j] = '\0';
164	return j;
165}
166EXPORT_SYMBOL(ucs2_as_utf8);
167
168MODULE_LICENSE("GPL v2");
169