2142cbd1dde243c1738ec389decd13ca9ce05158
[releases.git] / unicode.c
1 /*
2  * unicode.c
3  *
4  * PURPOSE
5  *      Routines for converting between UTF-8 and OSTA Compressed Unicode.
6  *      Also handles filename mangling
7  *
8  * DESCRIPTION
9  *      OSTA Compressed Unicode is explained in the OSTA UDF specification.
10  *              http://www.osta.org/
11  *      UTF-8 is explained in the IETF RFC XXXX.
12  *              ftp://ftp.internic.net/rfc/rfcxxxx.txt
13  *
14  * COPYRIGHT
15  *      This file is distributed under the terms of the GNU General Public
16  *      License (GPL). Copies of the GPL can be obtained from:
17  *              ftp://prep.ai.mit.edu/pub/gnu/GPL
18  *      Each contributing author retains all rights to their own work.
19  */
20
21 #include "udfdecl.h"
22
23 #include <linux/kernel.h>
24 #include <linux/string.h>       /* for memset */
25 #include <linux/nls.h>
26 #include <linux/crc-itu-t.h>
27 #include <linux/slab.h>
28
29 #include "udf_sb.h"
30
31 #define PLANE_SIZE 0x10000
32 #define UNICODE_MAX 0x10ffff
33 #define SURROGATE_MASK 0xfffff800
34 #define SURROGATE_PAIR 0x0000d800
35 #define SURROGATE_LOW  0x00000400
36 #define SURROGATE_CHAR_BITS 10
37 #define SURROGATE_CHAR_MASK ((1 << SURROGATE_CHAR_BITS) - 1)
38
39 #define ILLEGAL_CHAR_MARK       '_'
40 #define EXT_MARK                '.'
41 #define CRC_MARK                '#'
42 #define EXT_SIZE                5
43 /* Number of chars we need to store generated CRC to make filename unique */
44 #define CRC_LEN                 5
45
46 static unicode_t get_utf16_char(const uint8_t *str_i, int str_i_max_len,
47                                 int str_i_idx, int u_ch, unicode_t *ret)
48 {
49         unicode_t c;
50         int start_idx = str_i_idx;
51
52         /* Expand OSTA compressed Unicode to Unicode */
53         c = str_i[str_i_idx++];
54         if (u_ch > 1)
55                 c = (c << 8) | str_i[str_i_idx++];
56         if ((c & SURROGATE_MASK) == SURROGATE_PAIR) {
57                 unicode_t next;
58
59                 /* Trailing surrogate char */
60                 if (str_i_idx >= str_i_max_len) {
61                         c = UNICODE_MAX + 1;
62                         goto out;
63                 }
64
65                 /* Low surrogate must follow the high one... */
66                 if (c & SURROGATE_LOW) {
67                         c = UNICODE_MAX + 1;
68                         goto out;
69                 }
70
71                 WARN_ON_ONCE(u_ch != 2);
72                 next = str_i[str_i_idx++] << 8;
73                 next |= str_i[str_i_idx++];
74                 if ((next & SURROGATE_MASK) != SURROGATE_PAIR ||
75                     !(next & SURROGATE_LOW)) {
76                         c = UNICODE_MAX + 1;
77                         goto out;
78                 }
79
80                 c = PLANE_SIZE +
81                     ((c & SURROGATE_CHAR_MASK) << SURROGATE_CHAR_BITS) +
82                     (next & SURROGATE_CHAR_MASK);
83         }
84 out:
85         *ret = c;
86         return str_i_idx - start_idx;
87 }
88
89
90 static int udf_name_conv_char(uint8_t *str_o, int str_o_max_len,
91                               int *str_o_idx,
92                               const uint8_t *str_i, int str_i_max_len,
93                               int *str_i_idx,
94                               int u_ch, int *needsCRC,
95                               int (*conv_f)(wchar_t, unsigned char *, int),
96                               int translate)
97 {
98         unicode_t c;
99         int illChar = 0;
100         int len, gotch = 0;
101
102         while (!gotch && *str_i_idx < str_i_max_len) {
103                 if (*str_o_idx >= str_o_max_len) {
104                         *needsCRC = 1;
105                         return gotch;
106                 }
107
108                 len = get_utf16_char(str_i, str_i_max_len, *str_i_idx, u_ch,
109                                      &c);
110                 /* These chars cannot be converted. Replace them. */
111                 if (c == 0 || c > UNICODE_MAX || (conv_f && c > MAX_WCHAR_T) ||
112                     (translate && c == '/')) {
113                         illChar = 1;
114                         if (!translate)
115                                 gotch = 1;
116                 } else if (illChar)
117                         break;
118                 else
119                         gotch = 1;
120                 *str_i_idx += len;
121         }
122         if (illChar) {
123                 *needsCRC = 1;
124                 c = ILLEGAL_CHAR_MARK;
125                 gotch = 1;
126         }
127         if (gotch) {
128                 if (conv_f) {
129                         len = conv_f(c, &str_o[*str_o_idx],
130                                      str_o_max_len - *str_o_idx);
131                 } else {
132                         len = utf32_to_utf8(c, &str_o[*str_o_idx],
133                                             str_o_max_len - *str_o_idx);
134                         if (len < 0)
135                                 len = -ENAMETOOLONG;
136                 }
137                 /* Valid character? */
138                 if (len >= 0)
139                         *str_o_idx += len;
140                 else if (len == -ENAMETOOLONG) {
141                         *needsCRC = 1;
142                         gotch = 0;
143                 } else {
144                         str_o[(*str_o_idx)++] = ILLEGAL_CHAR_MARK;
145                         *needsCRC = 1;
146                 }
147         }
148         return gotch;
149 }
150
151 static int udf_name_from_CS0(struct super_block *sb,
152                              uint8_t *str_o, int str_max_len,
153                              const uint8_t *ocu, int ocu_len,
154                              int translate)
155 {
156         uint32_t c;
157         uint8_t cmp_id;
158         int idx, len;
159         int u_ch;
160         int needsCRC = 0;
161         int ext_i_len, ext_max_len;
162         int str_o_len = 0;      /* Length of resulting output */
163         int ext_o_len = 0;      /* Extension output length */
164         int ext_crc_len = 0;    /* Extension output length if used with CRC */
165         int i_ext = -1;         /* Extension position in input buffer */
166         int o_crc = 0;          /* Rightmost possible output pos for CRC+ext */
167         unsigned short valueCRC;
168         uint8_t ext[EXT_SIZE * NLS_MAX_CHARSET_SIZE + 1];
169         uint8_t crc[CRC_LEN];
170         int (*conv_f)(wchar_t, unsigned char *, int);
171
172         if (str_max_len <= 0)
173                 return 0;
174
175         if (ocu_len == 0) {
176                 memset(str_o, 0, str_max_len);
177                 return 0;
178         }
179
180         if (UDF_SB(sb)->s_nls_map)
181                 conv_f = UDF_SB(sb)->s_nls_map->uni2char;
182         else
183                 conv_f = NULL;
184
185         cmp_id = ocu[0];
186         if (cmp_id != 8 && cmp_id != 16) {
187                 memset(str_o, 0, str_max_len);
188                 pr_err("unknown compression code (%u)\n", cmp_id);
189                 return -EINVAL;
190         }
191         u_ch = cmp_id >> 3;
192
193         ocu++;
194         ocu_len--;
195
196         if (ocu_len % u_ch) {
197                 pr_err("incorrect filename length (%d)\n", ocu_len + 1);
198                 return -EINVAL;
199         }
200
201         if (translate) {
202                 /* Look for extension */
203                 for (idx = ocu_len - u_ch, ext_i_len = 0;
204                      (idx >= 0) && (ext_i_len < EXT_SIZE);
205                      idx -= u_ch, ext_i_len++) {
206                         c = ocu[idx];
207                         if (u_ch > 1)
208                                 c = (c << 8) | ocu[idx + 1];
209
210                         if (c == EXT_MARK) {
211                                 if (ext_i_len)
212                                         i_ext = idx;
213                                 break;
214                         }
215                 }
216                 if (i_ext >= 0) {
217                         /* Convert extension */
218                         ext_max_len = min_t(int, sizeof(ext), str_max_len);
219                         ext[ext_o_len++] = EXT_MARK;
220                         idx = i_ext + u_ch;
221                         while (udf_name_conv_char(ext, ext_max_len, &ext_o_len,
222                                                   ocu, ocu_len, &idx,
223                                                   u_ch, &needsCRC,
224                                                   conv_f, translate)) {
225                                 if ((ext_o_len + CRC_LEN) < str_max_len)
226                                         ext_crc_len = ext_o_len;
227                         }
228                 }
229         }
230
231         idx = 0;
232         while (1) {
233                 if (translate && (idx == i_ext)) {
234                         if (str_o_len > (str_max_len - ext_o_len))
235                                 needsCRC = 1;
236                         break;
237                 }
238
239                 if (!udf_name_conv_char(str_o, str_max_len, &str_o_len,
240                                         ocu, ocu_len, &idx,
241                                         u_ch, &needsCRC, conv_f, translate))
242                         break;
243
244                 if (translate &&
245                     (str_o_len <= (str_max_len - ext_o_len - CRC_LEN)))
246                         o_crc = str_o_len;
247         }
248
249         if (translate) {
250                 if (str_o_len > 0 && str_o_len <= 2 && str_o[0] == '.' &&
251                     (str_o_len == 1 || str_o[1] == '.'))
252                         needsCRC = 1;
253                 if (needsCRC) {
254                         str_o_len = o_crc;
255                         valueCRC = crc_itu_t(0, ocu, ocu_len);
256                         crc[0] = CRC_MARK;
257                         crc[1] = hex_asc_upper_hi(valueCRC >> 8);
258                         crc[2] = hex_asc_upper_lo(valueCRC >> 8);
259                         crc[3] = hex_asc_upper_hi(valueCRC);
260                         crc[4] = hex_asc_upper_lo(valueCRC);
261                         len = min_t(int, CRC_LEN, str_max_len - str_o_len);
262                         memcpy(&str_o[str_o_len], crc, len);
263                         str_o_len += len;
264                         ext_o_len = ext_crc_len;
265                 }
266                 if (ext_o_len > 0) {
267                         memcpy(&str_o[str_o_len], ext, ext_o_len);
268                         str_o_len += ext_o_len;
269                 }
270         }
271
272         return str_o_len;
273 }
274
275 static int udf_name_to_CS0(struct super_block *sb,
276                            uint8_t *ocu, int ocu_max_len,
277                            const uint8_t *str_i, int str_len)
278 {
279         int i, len;
280         unsigned int max_val;
281         int u_len, u_ch;
282         unicode_t uni_char;
283         int (*conv_f)(const unsigned char *, int, wchar_t *);
284
285         if (ocu_max_len <= 0)
286                 return 0;
287
288         if (UDF_SB(sb)->s_nls_map)
289                 conv_f = UDF_SB(sb)->s_nls_map->char2uni;
290         else
291                 conv_f = NULL;
292
293         memset(ocu, 0, ocu_max_len);
294         ocu[0] = 8;
295         max_val = 0xff;
296         u_ch = 1;
297
298 try_again:
299         u_len = 1;
300         for (i = 0; i < str_len; i += len) {
301                 /* Name didn't fit? */
302                 if (u_len + u_ch > ocu_max_len)
303                         return 0;
304                 if (conv_f) {
305                         wchar_t wchar;
306
307                         len = conv_f(&str_i[i], str_len - i, &wchar);
308                         if (len > 0)
309                                 uni_char = wchar;
310                 } else {
311                         len = utf8_to_utf32(&str_i[i], str_len - i,
312                                             &uni_char);
313                 }
314                 /* Invalid character, deal with it */
315                 if (len <= 0 || uni_char > UNICODE_MAX) {
316                         len = 1;
317                         uni_char = '?';
318                 }
319
320                 if (uni_char > max_val) {
321                         unicode_t c;
322
323                         if (max_val == 0xff) {
324                                 max_val = 0xffff;
325                                 ocu[0] = 0x10;
326                                 u_ch = 2;
327                                 goto try_again;
328                         }
329                         /*
330                          * Use UTF-16 encoding for chars outside we
331                          * cannot encode directly.
332                          */
333                         if (u_len + 2 * u_ch > ocu_max_len)
334                                 return 0;
335
336                         uni_char -= PLANE_SIZE;
337                         c = SURROGATE_PAIR |
338                             ((uni_char >> SURROGATE_CHAR_BITS) &
339                              SURROGATE_CHAR_MASK);
340                         ocu[u_len++] = (uint8_t)(c >> 8);
341                         ocu[u_len++] = (uint8_t)(c & 0xff);
342                         uni_char = SURROGATE_PAIR | SURROGATE_LOW |
343                                         (uni_char & SURROGATE_CHAR_MASK);
344                 }
345
346                 if (max_val == 0xffff)
347                         ocu[u_len++] = (uint8_t)(uni_char >> 8);
348                 ocu[u_len++] = (uint8_t)(uni_char & 0xff);
349         }
350
351         return u_len;
352 }
353
354 /*
355  * Convert CS0 dstring to output charset. Warning: This function may truncate
356  * input string if it is too long as it is used for informational strings only
357  * and it is better to truncate the string than to refuse mounting a media.
358  */
359 int udf_dstrCS0toChar(struct super_block *sb, uint8_t *utf_o, int o_len,
360                       const uint8_t *ocu_i, int i_len)
361 {
362         int s_len = 0;
363
364         if (i_len > 0) {
365                 s_len = ocu_i[i_len - 1];
366                 if (s_len >= i_len) {
367                         pr_warn("incorrect dstring lengths (%d/%d),"
368                                 " truncating\n", s_len, i_len);
369                         s_len = i_len - 1;
370                         /* 2-byte encoding? Need to round properly... */
371                         if (ocu_i[0] == 16)
372                                 s_len -= (s_len - 1) & 2;
373                 }
374         }
375
376         return udf_name_from_CS0(sb, utf_o, o_len, ocu_i, s_len, 0);
377 }
378
379 int udf_get_filename(struct super_block *sb, const uint8_t *sname, int slen,
380                      uint8_t *dname, int dlen)
381 {
382         int ret;
383
384         if (!slen)
385                 return -EIO;
386
387         if (dlen <= 0)
388                 return 0;
389
390         ret = udf_name_from_CS0(sb, dname, dlen, sname, slen, 1);
391         /* Zero length filename isn't valid... */
392         if (ret == 0)
393                 ret = -EINVAL;
394         return ret;
395 }
396
397 int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
398                      uint8_t *dname, int dlen)
399 {
400         return udf_name_to_CS0(sb, dname, dlen, sname, slen);
401 }
402