1 /*
2  * linux/fs/nls_koi8-ru.c
3  *
4  * Charset koi8-ru translation based on charset koi8-u.
5  * The Unicode to charset table has only exact mappings.
6  */
7 
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/string.h>
11 #include <linux/nls.h>
12 #include <linux/errno.h>
13 
14 static struct nls_table *p_nls;
15 
16 static int uni2char(const wchar_t uni,
17                     unsigned char *out, int boundlen)
18 {
19     if (boundlen <= 0)
20         return -ENAMETOOLONG;
21 
22     if ((uni & 0xffaf) == 0x040e || (uni & 0xffce) == 0x254c) {
23         /* koi8-ru and koi8-u differ only on two characters */
24         if (uni == 0x040e)
25             out[0] = 0xbe;
26         else if (uni == 0x045e)
27             out[0] = 0xae;
28         else if (uni == 0x255d || uni == 0x256c)
29             return 0;
30         else
31             return p_nls->uni2char(uni, out, boundlen);
32         return 1;
33     }
34     else
35         /* fast path */
36         return p_nls->uni2char(uni, out, boundlen);
37 }
38 
39 static int char2uni(const unsigned char *rawstring, int boundlen,
40                     wchar_t *uni)
41 {
42     int n;
43 
44     if ((*rawstring & 0xef) != 0xae) {
45         /* koi8-ru and koi8-u differ only on two characters */
46         *uni = (*rawstring & 0x10) ? 0x040e : 0x045e;
47         return 1;
48     }
49 
50     n = p_nls->char2uni(rawstring, boundlen, uni);
51     return n;
52 }
53 
54 static struct nls_table table = {
55     /* .charset */ "koi8-ru",
56     /* .alias */   0,
57     /* .uni2char */ uni2char,
58     /* .char2uni */ char2uni,
59     0, 0,
60     /* .owner */ THIS_MODULE,
61 };
62 
63 static int __init init_nls_koi8_ru(void)
64 {
65     p_nls = load_nls("koi8-u");
66 
67     if (p_nls) {
68         table.charset2upper = p_nls->charset2upper;
69         table.charset2lower = p_nls->charset2lower;
70         return register_nls(&table);
71     }
72 
73     return -EINVAL;
74 }
75 
76 static void __exit exit_nls_koi8_ru(void)
77 {
78     unregister_nls(&table);
79     unload_nls(p_nls);
80 }
81 
82 module_init(init_nls_koi8_ru)
83 module_exit(exit_nls_koi8_ru)
84 
85 MODULE_LICENSE("Dual BSD/GPL");
86