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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2003 David Brownell | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU Lesser General Public License as published | |
6 | * by the Free Software Foundation; either version 2.1 of the License, or | |
7 | * (at your option) any later version. | |
8 | */ | |
9 | ||
10 | #include <linux/errno.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/list.h> | |
13 | #include <linux/string.h> | |
14 | #include <linux/device.h> | |
15 | #include <linux/init.h> | |
16 | ||
5f848137 | 17 | #include <linux/usb/ch9.h> |
9454a57a | 18 | #include <linux/usb/gadget.h> |
1da177e4 LT |
19 | |
20 | #include <asm/unaligned.h> | |
21 | ||
22 | ||
23 | static int utf8_to_utf16le(const char *s, __le16 *cp, unsigned len) | |
24 | { | |
25 | int count = 0; | |
26 | u8 c; | |
27 | u16 uchar; | |
28 | ||
29 | /* this insists on correct encodings, though not minimal ones. | |
30 | * BUT it currently rejects legit 4-byte UTF-8 code points, | |
31 | * which need surrogate pairs. (Unicode 3.1 can use them.) | |
32 | */ | |
33 | while (len != 0 && (c = (u8) *s++) != 0) { | |
34 | if (unlikely(c & 0x80)) { | |
35 | // 2-byte sequence: | |
36 | // 00000yyyyyxxxxxx = 110yyyyy 10xxxxxx | |
37 | if ((c & 0xe0) == 0xc0) { | |
38 | uchar = (c & 0x1f) << 6; | |
39 | ||
40 | c = (u8) *s++; | |
0f43158c | 41 | if ((c & 0xc0) != 0x80) |
1da177e4 LT |
42 | goto fail; |
43 | c &= 0x3f; | |
44 | uchar |= c; | |
45 | ||
46 | // 3-byte sequence (most CJKV characters): | |
47 | // zzzzyyyyyyxxxxxx = 1110zzzz 10yyyyyy 10xxxxxx | |
48 | } else if ((c & 0xf0) == 0xe0) { | |
49 | uchar = (c & 0x0f) << 12; | |
50 | ||
51 | c = (u8) *s++; | |
0f43158c | 52 | if ((c & 0xc0) != 0x80) |
1da177e4 LT |
53 | goto fail; |
54 | c &= 0x3f; | |
55 | uchar |= c << 6; | |
56 | ||
57 | c = (u8) *s++; | |
0f43158c | 58 | if ((c & 0xc0) != 0x80) |
1da177e4 LT |
59 | goto fail; |
60 | c &= 0x3f; | |
61 | uchar |= c; | |
62 | ||
63 | /* no bogus surrogates */ | |
64 | if (0xd800 <= uchar && uchar <= 0xdfff) | |
65 | goto fail; | |
66 | ||
67 | // 4-byte sequence (surrogate pairs, currently rare): | |
68 | // 11101110wwwwzzzzyy + 110111yyyyxxxxxx | |
69 | // = 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx | |
70 | // (uuuuu = wwww + 1) | |
71 | // FIXME accept the surrogate code points (only) | |
72 | ||
73 | } else | |
74 | goto fail; | |
75 | } else | |
76 | uchar = c; | |
a5abdeaf | 77 | put_unaligned_le16(uchar, cp++); |
1da177e4 LT |
78 | count++; |
79 | len--; | |
80 | } | |
81 | return count; | |
82 | fail: | |
83 | return -1; | |
84 | } | |
85 | ||
86 | ||
87 | /** | |
88 | * usb_gadget_get_string - fill out a string descriptor | |
89 | * @table: of c strings encoded using UTF-8 | |
90 | * @id: string id, from low byte of wValue in get string descriptor | |
91 | * @buf: at least 256 bytes | |
92 | * | |
93 | * Finds the UTF-8 string matching the ID, and converts it into a | |
94 | * string descriptor in utf16-le. | |
95 | * Returns length of descriptor (always even) or negative errno | |
96 | * | |
97 | * If your driver needs stings in multiple languages, you'll probably | |
98 | * "switch (wIndex) { ... }" in your ep0 string descriptor logic, | |
99 | * using this routine after choosing which set of UTF-8 strings to use. | |
100 | * Note that US-ASCII is a strict subset of UTF-8; any string bytes with | |
101 | * the eighth bit set will be multibyte UTF-8 characters, not ISO-8859/1 | |
102 | * characters (which are also widely used in C strings). | |
103 | */ | |
104 | int | |
105 | usb_gadget_get_string (struct usb_gadget_strings *table, int id, u8 *buf) | |
106 | { | |
107 | struct usb_string *s; | |
108 | int len; | |
109 | ||
110 | /* descriptor 0 has the language id */ | |
111 | if (id == 0) { | |
112 | buf [0] = 4; | |
113 | buf [1] = USB_DT_STRING; | |
114 | buf [2] = (u8) table->language; | |
115 | buf [3] = (u8) (table->language >> 8); | |
116 | return 4; | |
117 | } | |
118 | for (s = table->strings; s && s->s; s++) | |
119 | if (s->id == id) | |
120 | break; | |
121 | ||
122 | /* unrecognized: stall. */ | |
123 | if (!s || !s->s) | |
124 | return -EINVAL; | |
125 | ||
126 | /* string descriptors have length, tag, then UTF16-LE text */ | |
127 | len = min ((size_t) 126, strlen (s->s)); | |
128 | memset (buf + 2, 0, 2 * len); /* zero all the bytes */ | |
129 | len = utf8_to_utf16le(s->s, (__le16 *)&buf[2], len); | |
130 | if (len < 0) | |
131 | return -EINVAL; | |
132 | buf [0] = (len + 1) * 2; | |
133 | buf [1] = USB_DT_STRING; | |
134 | return buf [0]; | |
135 | } | |
136 |