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11  * wchar_t values is now outdated.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