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