linux/fs/udf/unicode.c
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   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
  46static 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        }
  84out:
  85        *ret = c;
  86        return str_i_idx - start_idx;
  87}
  88
  89
  90static 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
 151static 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_QUERY_FLAG(sb, UDF_FLAG_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 <= 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
 275static 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_QUERY_FLAG(sb, UDF_FLAG_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
 298try_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
 354int udf_dstrCS0toChar(struct super_block *sb, uint8_t *utf_o, int o_len,
 355                      const uint8_t *ocu_i, int i_len)
 356{
 357        int s_len = 0;
 358
 359        if (i_len > 0) {
 360                s_len = ocu_i[i_len - 1];
 361                if (s_len >= i_len) {
 362                        pr_err("incorrect dstring lengths (%d/%d)\n",
 363                               s_len, i_len);
 364                        return -EINVAL;
 365                }
 366        }
 367
 368        return udf_name_from_CS0(sb, utf_o, o_len, ocu_i, s_len, 0);
 369}
 370
 371int udf_get_filename(struct super_block *sb, const uint8_t *sname, int slen,
 372                     uint8_t *dname, int dlen)
 373{
 374        int ret;
 375
 376        if (!slen)
 377                return -EIO;
 378
 379        if (dlen <= 0)
 380                return 0;
 381
 382        ret = udf_name_from_CS0(sb, dname, dlen, sname, slen, 1);
 383        /* Zero length filename isn't valid... */
 384        if (ret == 0)
 385                ret = -EINVAL;
 386        return ret;
 387}
 388
 389int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
 390                     uint8_t *dname, int dlen)
 391{
 392        return udf_name_to_CS0(sb, dname, dlen, sname, slen);
 393}
 394
 395