1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_NLS_H
3#define _LINUX_NLS_H
4
5#include <linux/init.h>
6
7/* Unicode has changed over the years. Unicode code points no longer
8 * fit into 16 bits; as of Unicode 5 valid code points range from 0
9 * to 0x10ffff (17 planes, where each plane holds 65536 code points).
10 *
11 * The original decision to represent Unicode characters as 16-bit
12 * wchar_t values is now outdated. But plane 0 still includes the
13 * most commonly used characters, so we will retain it. The newer
14 * 32-bit unicode_t type can be used when it is necessary to
15 * represent the full Unicode character set.
16 */
17
18/* Plane-0 Unicode character */
19typedef u16 wchar_t;
20#define MAX_WCHAR_T 0xffff
21
22/* Arbitrary Unicode character */
23typedef u32 unicode_t;
24
25struct nls_table {
26 const char *charset;
27 const char *alias;
28 int (*uni2char) (wchar_t uni, unsigned char *out, int boundlen);
29 int (*char2uni) (const unsigned char *rawstring, int boundlen,
30 wchar_t *uni);
31 const unsigned char *charset2lower;
32 const unsigned char *charset2upper;
33 struct module *owner;
34 struct nls_table *next;
35};
36
37/* this value hold the maximum octet of charset */
38#define NLS_MAX_CHARSET_SIZE 6 /* for UTF-8 */
39
40/* Byte order for UTF-16 strings */
41enum utf16_endian {
42 UTF16_HOST_ENDIAN,
43 UTF16_LITTLE_ENDIAN,
44 UTF16_BIG_ENDIAN
45};
46
47/* nls_base.c */
48extern int __register_nls(struct nls_table *, struct module *);
49extern int unregister_nls(struct nls_table *);
50extern struct nls_table *load_nls(const char *charset);
51extern void unload_nls(struct nls_table *);
52extern struct nls_table *load_nls_default(void);
53#define register_nls(nls) __register_nls((nls), THIS_MODULE)
54
55extern int utf8_to_utf32(const u8 *s, int len, unicode_t *pu);
56extern int utf32_to_utf8(unicode_t u, u8 *s, int maxlen);
57extern int utf8s_to_utf16s(const u8 *s, int len,
58 enum utf16_endian endian, wchar_t *pwcs, int maxlen);
59extern int utf16s_to_utf8s(const wchar_t *pwcs, int len,
60 enum utf16_endian endian, u8 *s, int maxlen);
61
62static inline unsigned char nls_tolower(struct nls_table *t, unsigned char c)
63{
64 unsigned char nc = t->charset2lower[c];
65
66 return nc ? nc : c;
67}
68
69static inline unsigned char nls_toupper(struct nls_table *t, unsigned char c)
70{
71 unsigned char nc = t->charset2upper[c];
72
73 return nc ? nc : c;
74}
75
76static inline int nls_strnicmp(struct nls_table *t, const unsigned char *s1,
77 const unsigned char *s2, int len)
78{
79 while (len--) {
80 if (nls_tolower(t, c: *s1++) != nls_tolower(t, c: *s2++))
81 return 1;
82 }
83
84 return 0;
85}
86
87/*
88 * nls_nullsize - return length of null character for codepage
89 * @codepage - codepage for which to return length of NULL terminator
90 *
91 * Since we can't guarantee that the null terminator will be a particular
92 * length, we have to check against the codepage. If there's a problem
93 * determining it, assume a single-byte NULL terminator.
94 */
95static inline int
96nls_nullsize(const struct nls_table *codepage)
97{
98 int charlen;
99 char tmp[NLS_MAX_CHARSET_SIZE];
100
101 charlen = codepage->uni2char(0, tmp, NLS_MAX_CHARSET_SIZE);
102
103 return charlen > 0 ? charlen : 1;
104}
105
106#define MODULE_ALIAS_NLS(name) MODULE_ALIAS("nls_" __stringify(name))
107
108#endif /* _LINUX_NLS_H */
109
110