source/lib/iconv.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    minimal iconv implementation
   4    Copyright (C) Andrew Tridgell 2001
   5    Copyright (C) Jelmer Vernooij 2002,2003
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.h"
  23
  24 /*
  25  * We have to use strcasecmp here as the character conversions
  26  * haven't been initialised yet. JRA.
  27  */
  28
  29 #undef strcasecmp
  30
  31 /**
  32  * @file
  33  *
  34  * @brief Samba wrapper/stub for iconv character set conversion.
  35  *
  36  * iconv is the XPG2 interface for converting between character
  37  * encodings.  This file provides a Samba wrapper around it, and also
  38  * a simple reimplementation that is used if the system does not
  39  * implement iconv.
  40  *
  41  * Samba only works with encodings that are supersets of ASCII: ascii
  42  * characters like whitespace can be tested for directly, multibyte
  43  * sequences start with a byte with the high bit set, and strings are
  44  * terminated by a nul byte.
  45  *
  46  * Note that the only function provided by iconv is conversion between
  47  * characters.  It doesn't directly support operations like
  48  * uppercasing or comparison.  We have to convert to UCS-2 and compare
  49  * there.
  50  *
  51  * @sa Samba Developers Guide
  52  **/
  53
  54 static size_t ascii_pull(void *,const char **, size_t *, char **, size_t *);
  55 static size_t ascii_push(void *,const char **, size_t *, char **, size_t *);
  56 static size_t latin1_push(void *,const char **, size_t *, char **, size_t *);
  57 static size_t  utf8_pull(void *,const char **, size_t *, char **, size_t *);
  58 static size_t  utf8_push(void *,const char **, size_t *, char **, size_t *);
  59 static size_t ucs2hex_pull(void *,const char **, size_t *, char **, size_t *);
  60 static size_t ucs2hex_push(void *,const char **, size_t *, char **, size_t *);
  61 static size_t iconv_copy(void *,const char **, size_t *, char **, size_t *);
  62 static size_t iconv_swab  (void *,const char **, size_t *, char **, size_t *);
  63
  64 static struct charset_functions builtin_functions[] = {
  65         /* windows is really neither UCS-2 not UTF-16 */
  66         {"UCS-2LE",  iconv_copy, iconv_copy},
  67         {"UTF-16LE",  iconv_copy, iconv_copy},
  68         {"UCS-2BE",  iconv_swab, iconv_swab},
  69         {"UTF-16BE",  iconv_swab, iconv_swab},
  70
  71         /* we include the UTF-8 alias to cope with differing locale settings */
  72         {"UTF8",   utf8_pull,  utf8_push},
  73         {"UTF-8",   utf8_pull,  utf8_push},
  74         {"ASCII", ascii_pull, ascii_push},
  75         {"646", ascii_pull, ascii_push},
  76         {"ISO-8859-1", ascii_pull, latin1_push},
  77         {"UCS2-HEX", ucs2hex_pull, ucs2hex_push},
  78         {NULL, NULL, NULL}
  79 };
  80
  81 static struct charset_functions *charsets = NULL;
  82
  83 static struct charset_functions *find_charset_functions(const char *name)
  84 {
  85         struct charset_functions *c = charsets;
  86
  87         while(c) {
  88                 if (strcasecmp(name, c->name) == 0) {
  89                         return c;
  90                 }
  91                 c = c->next;
  92         }
  93
  94         return NULL;
  95 }
  96
  97 NTSTATUS smb_register_charset(struct charset_functions *funcs)
  98 {
  99         if (!funcs) {
 100                 return NT_STATUS_INVALID_PARAMETER;
 101         }
 102
 103         DEBUG(5, ("Attempting to register new charset %s\n", funcs->name));
 104         /* Check whether we already have this charset... */
 105         if (find_charset_functions(funcs->name)) {
 106                 DEBUG(0, ("Duplicate charset %s, not registering\n", funcs->name));
 107                 return NT_STATUS_OBJECT_NAME_COLLISION;
 108         }
 109
 110         funcs->next = funcs->prev = NULL;
 111         DEBUG(5, ("Registered charset %s\n", funcs->name));
 112         DLIST_ADD(charsets, funcs);
 113         return NT_STATUS_OK;
 114 }
 115
 116 static void lazy_initialize_iconv(void)
 117 {
 118         static BOOL initialized;
 119         int i;
 120
 121         if (!initialized) {
 122                 initialized = True;
 123                 for(i = 0; builtin_functions[i].name; i++)
 124                         smb_register_charset(&builtin_functions[i]);
 125                 static_init_charset;
 126         }
 127 }
 128
 129 /* if there was an error then reset the internal state,
 130    this ensures that we don't have a shift state remaining for
 131    character sets like SJIS */
 132 static size_t sys_iconv(void *cd,
 133                         const char **inbuf, size_t *inbytesleft,
 134                         char **outbuf, size_t *outbytesleft)
 135 {
 136 #ifdef HAVE_NATIVE_ICONV
 137         size_t ret = iconv((iconv_t)cd,
 138                            (char **)inbuf, inbytesleft,
 139                            outbuf, outbytesleft);
 140         if (ret == (size_t)-1) {
 141                 int saved_errno = errno;
 142                 iconv(cd, NULL, NULL, NULL, NULL);
 143                 errno = saved_errno;
 144         }
 145         return ret;
 146 #else
 147         errno = EINVAL;
 148         return -1;
 149 #endif
 150 }
 151
 152 /**
 153  * This is a simple portable iconv() implementaion.
 154  *
 155  * It only knows about a very small number of character sets - just
 156  * enough that Samba works on systems that don't have iconv.
 157  **/
 158 size_t smb_iconv(smb_iconv_t cd,
 159                  const char **inbuf, size_t *inbytesleft,
 160                  char **outbuf, size_t *outbytesleft)
 161 {
 162         char cvtbuf[2048];
 163         char *bufp = cvtbuf;
 164         size_t bufsize;
 165
 166         /* in many cases we can go direct */
 167         if (cd->direct) {
 168                 return cd->direct(cd->cd_direct,
 169                                   inbuf, inbytesleft, outbuf, outbytesleft);
 170         }
 171
 172
 173         /* otherwise we have to do it chunks at a time */
 174         while (*inbytesleft > 0) {
 175                 bufp = cvtbuf;
 176                 bufsize = sizeof(cvtbuf);
 177
 178                 if (cd->pull(cd->cd_pull,
 179                              inbuf, inbytesleft, &bufp, &bufsize) == -1
 180                     && errno != E2BIG) return -1;
 181
 182                 bufp = cvtbuf;
 183                 bufsize = sizeof(cvtbuf) - bufsize;
 184
 185                 if (cd->push(cd->cd_push,
 186                              (const char **)&bufp, &bufsize,
 187                              outbuf, outbytesleft) == -1) return -1;
 188         }
 189
 190         return 0;
 191 }
 192
 193
 194 static BOOL is_utf16(const char *name)
 195 {
 196         return strcasecmp(name, "UCS-2LE") == 0 ||
 197                 strcasecmp(name, "UTF-16LE") == 0;
 198 }
 199
 200 /*
 201   simple iconv_open() wrapper
 202  */
 203 smb_iconv_t smb_iconv_open(const char *tocode, const char *fromcode)
 204 {
 205         smb_iconv_t ret;
 206         struct charset_functions *from, *to;
 207
 208         lazy_initialize_iconv();
 209         from = charsets;
 210         to = charsets;
 211
 212         ret = (smb_iconv_t)malloc(sizeof(*ret));
 213         if (!ret) {
 214                 errno = ENOMEM;
 215                 return (smb_iconv_t)-1;
 216         }
 217         memset(ret, 0, sizeof(*ret));
 218
 219         ret->from_name = strdup(fromcode);
 220         ret->to_name = strdup(tocode);
 221
 222         /* check for the simplest null conversion */
 223         if (strcasecmp(fromcode, tocode) == 0) {
 224                 ret->direct = iconv_copy;
 225                 return ret;
 226         }
 227
 228         /* check if we have a builtin function for this conversion */
 229         from = find_charset_functions(fromcode);
 230         if(from)ret->pull = from->pull;
 231
 232         to = find_charset_functions(tocode);
 233         if(to)ret->push = to->push;
 234
 235         /* check if we can use iconv for this conversion */
 236 #ifdef HAVE_NATIVE_ICONV
 237         if (!ret->pull) {
 238                 ret->cd_pull = iconv_open("UTF-16LE", fromcode);
 239                 if (ret->cd_pull == (iconv_t)-1)
 240                         ret->cd_pull = iconv_open("UCS-2LE", fromcode);
 241                 if (ret->cd_pull != (iconv_t)-1)
 242                         ret->pull = sys_iconv;
 243         }
 244
 245         if (!ret->push) {
 246                 ret->cd_push = iconv_open(tocode, "UTF-16LE");
 247                 if (ret->cd_push == (iconv_t)-1)
 248                         ret->cd_push = iconv_open(tocode, "UCS-2LE");
 249                 if (ret->cd_push != (iconv_t)-1)
 250                         ret->push = sys_iconv;
 251         }
 252 #endif
 253
 254         /* check if there is a module available that can do this conversion */
 255         if (!ret->pull && NT_STATUS_IS_OK(smb_probe_module("charset", fromcode))) {
 256                 if(!(from = find_charset_functions(fromcode)))
 257                         DEBUG(0, ("Module %s doesn't provide charset %s!\n", fromcode, fromcode));
 258                 else
 259                         ret->pull = from->pull;
 260         }
 261
 262         if (!ret->push && NT_STATUS_IS_OK(smb_probe_module("charset", tocode))) {
 263                 if(!(to = find_charset_functions(tocode)))
 264                         DEBUG(0, ("Module %s doesn't provide charset %s!\n", tocode, tocode));
 265                 else
 266                         ret->push = to->push;
 267         }
 268
 269         if (!ret->push || !ret->pull) {
 270                 SAFE_FREE(ret->from_name);
 271                 SAFE_FREE(ret->to_name);
 272                 SAFE_FREE(ret);
 273                 errno = EINVAL;
 274                 return (smb_iconv_t)-1;
 275         }
 276
 277         /* check for conversion to/from ucs2 */
 278         if (is_utf16(fromcode) && to) {
 279                 ret->direct = to->push;
 280                 ret->push = ret->pull = NULL;
 281                 return ret;
 282         }
 283
 284         if (is_utf16(tocode) && from) {
 285                 ret->direct = from->pull;
 286                 ret->push = ret->pull = NULL;
 287                 return ret;
 288         }
 289
 290         /* Check if we can do the conversion direct */
 291 #ifdef HAVE_NATIVE_ICONV
 292         if (is_utf16(fromcode)) {
 293                 ret->direct = sys_iconv;
 294                 ret->cd_direct = ret->cd_push;
 295                 ret->cd_push = NULL;
 296                 return ret;
 297         }
 298         if (is_utf16(tocode)) {
 299                 ret->direct = sys_iconv;
 300                 ret->cd_direct = ret->cd_pull;
 301                 ret->cd_pull = NULL;
 302                 return ret;
 303         }
 304 #endif
 305
 306         return ret;
 307 }
 308
 309 /*
 310   simple iconv_close() wrapper
 311 */
 312 int smb_iconv_close (smb_iconv_t cd)
 313 {
 314 #ifdef HAVE_NATIVE_ICONV
 315         if (cd->cd_direct) iconv_close((iconv_t)cd->cd_direct);
 316         if (cd->cd_pull) iconv_close((iconv_t)cd->cd_pull);
 317         if (cd->cd_push) iconv_close((iconv_t)cd->cd_push);
 318 #endif
 319
 320         SAFE_FREE(cd->from_name);
 321         SAFE_FREE(cd->to_name);
 322
 323         memset(cd, 0, sizeof(*cd));
 324         SAFE_FREE(cd);
 325         return 0;
 326 }
 327
 328
 329 /**********************************************************************
 330  the following functions implement the builtin character sets in Samba
 331  and also the "test" character sets that are designed to test
 332  multi-byte character set support for english users
 333 ***********************************************************************/
 334
 335 static size_t ascii_pull(void *cd, const char **inbuf, size_t *inbytesleft,
 336                          char **outbuf, size_t *outbytesleft)
 337 {
 338         while (*inbytesleft >= 1 && *outbytesleft >= 2) {
 339                 (*outbuf)[0] = (*inbuf)[0];
 340                 (*outbuf)[1] = 0;
 341                 (*inbytesleft)  -= 1;
 342                 (*outbytesleft) -= 2;
 343                 (*inbuf)  += 1;
 344                 (*outbuf) += 2;
 345         }
 346
 347         if (*inbytesleft > 0) {
 348                 errno = E2BIG;
 349                 return -1;
 350         }
 351
 352         return 0;
 353 }
 354
 355 static size_t ascii_push(void *cd, const char **inbuf, size_t *inbytesleft,
 356                          char **outbuf, size_t *outbytesleft)
 357 {
 358         int ir_count=0;
 359
 360         while (*inbytesleft >= 2 && *outbytesleft >= 1) {
 361                 (*outbuf)[0] = (*inbuf)[0] & 0x7F;
 362                 if ((*inbuf)[1]) ir_count++;
 363                 (*inbytesleft)  -= 2;
 364                 (*outbytesleft) -= 1;
 365                 (*inbuf)  += 2;
 366                 (*outbuf) += 1;
 367         }
 368
 369         if (*inbytesleft == 1) {
 370                 errno = EINVAL;
 371                 return -1;
 372         }
 373
 374         if (*inbytesleft > 1) {
 375                 errno = E2BIG;
 376                 return -1;
 377         }
 378
 379         return ir_count;
 380 }
 381
 382 static size_t latin1_push(void *cd, const char **inbuf, size_t *inbytesleft,
 383                          char **outbuf, size_t *outbytesleft)
 384 {
 385         int ir_count=0;
 386
 387         while (*inbytesleft >= 2 && *outbytesleft >= 1) {
 388                 (*outbuf)[0] = (*inbuf)[0];
 389                 if ((*inbuf)[1]) ir_count++;
 390                 (*inbytesleft)  -= 2;
 391                 (*outbytesleft) -= 1;
 392                 (*inbuf)  += 2;
 393                 (*outbuf) += 1;
 394         }
 395
 396         if (*inbytesleft == 1) {
 397                 errno = EINVAL;
 398                 return -1;
 399         }
 400
 401         if (*inbytesleft > 1) {
 402                 errno = E2BIG;
 403                 return -1;
 404         }
 405
 406         return ir_count;
 407 }
 408
 409 static size_t ucs2hex_pull(void *cd, const char **inbuf, size_t *inbytesleft,
 410                          char **outbuf, size_t *outbytesleft)
 411 {
 412         while (*inbytesleft >= 1 && *outbytesleft >= 2) {
 413                 unsigned v;
 414
 415                 if ((*inbuf)[0] != '@') {
 416                         /* seven bit ascii case */
 417                         (*outbuf)[0] = (*inbuf)[0];
 418                         (*outbuf)[1] = 0;
 419                         (*inbytesleft)  -= 1;
 420                         (*outbytesleft) -= 2;
 421                         (*inbuf)  += 1;
 422                         (*outbuf) += 2;
 423                         continue;
 424                 }
 425                 /* it's a hex character */
 426                 if (*inbytesleft < 5) {
 427                         errno = EINVAL;
 428                         return -1;
 429                 }
 430
 431                 if (sscanf(&(*inbuf)[1], "%04x", &v) != 1) {
 432                         errno = EILSEQ;
 433                         return -1;
 434                 }
 435
 436                 (*outbuf)[0] = v&0xff;
 437                 (*outbuf)[1] = v>>8;
 438                 (*inbytesleft)  -= 5;
 439                 (*outbytesleft) -= 2;
 440                 (*inbuf)  += 5;
 441                 (*outbuf) += 2;
 442         }
 443
 444         if (*inbytesleft > 0) {
 445                 errno = E2BIG;
 446                 return -1;
 447         }
 448
 449         return 0;
 450 }
 451
 452 static size_t ucs2hex_push(void *cd, const char **inbuf, size_t *inbytesleft,
 453                            char **outbuf, size_t *outbytesleft)
 454 {
 455         while (*inbytesleft >= 2 && *outbytesleft >= 1) {
 456                 char buf[6];
 457
 458                 if ((*inbuf)[1] == 0 &&
 459                     ((*inbuf)[0] & 0x80) == 0 &&
 460                     (*inbuf)[0] != '@') {
 461                         (*outbuf)[0] = (*inbuf)[0];
 462                         (*inbytesleft)  -= 2;
 463                         (*outbytesleft) -= 1;
 464                         (*inbuf)  += 2;
 465                         (*outbuf) += 1;
 466                         continue;
 467                 }
 468                 if (*outbytesleft < 5) {
 469                         errno = E2BIG;
 470                         return -1;
 471                 }
 472                 snprintf(buf, 6, "@%04x", SVAL(*inbuf, 0));
 473                 memcpy(*outbuf, buf, 5);
 474                 (*inbytesleft)  -= 2;
 475                 (*outbytesleft) -= 5;
 476                 (*inbuf)  += 2;
 477                 (*outbuf) += 5;
 478         }
 479
 480         if (*inbytesleft == 1) {
 481                 errno = EINVAL;
 482                 return -1;
 483         }
 484
 485         if (*inbytesleft > 1) {
 486                 errno = E2BIG;
 487                 return -1;
 488         }
 489
 490         return 0;
 491 }
 492
 493 static size_t iconv_swab(void *cd, const char **inbuf, size_t *inbytesleft,
 494                          char **outbuf, size_t *outbytesleft)
 495 {
 496         int n;
 497
 498         n = MIN(*inbytesleft, *outbytesleft);
 499
 500         swab(*inbuf, *outbuf, (n&~1));
 501         if (n&1) {
 502                 (*outbuf)[n-1] = 0;
 503         }
 504
 505         (*inbytesleft) -= n;
 506         (*outbytesleft) -= n;
 507         (*inbuf) += n;
 508         (*outbuf) += n;
 509
 510         if (*inbytesleft > 0) {
 511                 errno = E2BIG;
 512                 return -1;
 513         }
 514
 515         return 0;
 516 }
 517
 518 static size_t iconv_copy(void *cd, const char **inbuf, size_t *inbytesleft,
 519                          char **outbuf, size_t *outbytesleft)
 520 {
 521         int n;
 522
 523         n = MIN(*inbytesleft, *outbytesleft);
 524
 525         memmove(*outbuf, *inbuf, n);
 526
 527         (*inbytesleft) -= n;
 528         (*outbytesleft) -= n;
 529         (*inbuf) += n;
 530         (*outbuf) += n;
 531
 532         if (*inbytesleft > 0) {
 533                 errno = E2BIG;
 534                 return -1;
 535         }
 536
 537         return 0;
 538 }
 539
 540 static size_t utf8_pull(void *cd, const char **inbuf, size_t *inbytesleft,
 541                          char **outbuf, size_t *outbytesleft)
 542 {
 543         size_t in_left=*inbytesleft, out_left=*outbytesleft;
 544         const uint8 *c = (const uint8 *)*inbuf;
 545         uint8 *uc = (uint8 *)*outbuf;
 546
 547         while (in_left >= 1 && out_left >= 2) {
 548                 if ((c[0] & 0x80) == 0) {
 549                         uc[0] = c[0];
 550                         uc[1] = 0;
 551                         c  += 1;
 552                         in_left  -= 1;
 553                         out_left -= 2;
 554                         uc += 2;
 555                         continue;
 556                 }
 557
 558                 if ((c[0] & 0xe0) == 0xc0) {
 559                         if (in_left < 2 ||
 560                             (c[1] & 0xc0) != 0x80) {
 561                                 errno = EILSEQ;
 562                                 goto error;
 563                         }
 564                         uc[1] = (c[0]>>2) & 0x7;
 565                         uc[0] = (c[0]<<6) | (c[1]&0x3f);
 566                         c  += 2;
 567                         in_left  -= 2;
 568                         out_left -= 2;
 569                         uc += 2;
 570                         continue;
 571                 }
 572
 573                 if ((c[0] & 0xf0) == 0xe0) {
 574                         if (in_left < 3 ||
 575                             (c[1] & 0xc0) != 0x80 ||
 576                             (c[2] & 0xc0) != 0x80) {
 577                                 errno = EILSEQ;
 578                                 goto error;
 579                         }
 580                         uc[1] = ((c[0]&0xF)<<4) | ((c[1]>>2)&0xF);
 581                         uc[0] = (c[1]<<6) | (c[2]&0x3f);
 582                         c  += 3;
 583                         in_left  -= 3;
 584                         out_left -= 2;
 585                         uc += 2;
 586                         continue;
 587                 }
 588
 589                 if ((c[0] & 0xf8) == 0xf0) {
 590                         unsigned int codepoint;
 591                         if (in_left < 4 ||
 592                             (c[1] & 0xc0) != 0x80 ||
 593                             (c[2] & 0xc0) != 0x80 ||
 594                             (c[3] & 0xc0) != 0x80) {
 595                                 errno = EILSEQ;
 596                                 goto error;
 597                         }
 598                         codepoint =
 599                                 (c[3]&0x3f) |
 600                                 ((c[2]&0x3f)<<6) |
 601                                 ((c[1]&0x3f)<<12) |
 602                                 ((c[0]&0x7)<<18);
 603                         if (codepoint < 0x10000) {
 604                                 /* accept UTF-8 characters that are not
 605                                    minimally packed, but pack the result */
 606                                 uc[0] = (codepoint & 0xFF);
 607                                 uc[1] = (codepoint >> 8);
 608                                 c += 4;
 609                                 in_left -= 4;
 610                                 out_left -= 2;
 611                                 uc += 2;
 612                                 continue;
 613                         }
 614
 615                         codepoint -= 0x10000;
 616
 617                         if (out_left < 4) {
 618                                 errno = E2BIG;
 619                                 goto error;
 620                         }
 621
 622                         uc[0] = (codepoint>>10) & 0xFF;
 623                         uc[1] = (codepoint>>18) | 0xd8;
 624                         uc[2] = codepoint & 0xFF;
 625                         uc[3] = ((codepoint>>8) & 0x3) | 0xdc;
 626                         c  += 4;
 627                         in_left  -= 4;
 628                         out_left -= 4;
 629                         uc += 4;
 630                         continue;
 631                 }
 632
 633                 /* we don't handle 5 byte sequences */
 634                 errno = EINVAL;
 635                 goto error;
 636         }
 637
 638         if (in_left > 0) {
 639                 errno = E2BIG;
 640                 goto error;
 641         }
 642
 643         *inbytesleft = in_left;
 644         *outbytesleft = out_left;
 645         *inbuf = c;
 646         *outbuf = uc;
 647         return 0;
 648
 649 error:
 650         *inbytesleft = in_left;
 651         *outbytesleft = out_left;
 652         *inbuf = c;
 653         *outbuf = uc;
 654         return -1;
 655 }
 656
 657 static size_t utf8_push(void *cd, const char **inbuf, size_t *inbytesleft,
 658                         char **outbuf, size_t *outbytesleft)
 659 {
 660         size_t in_left=*inbytesleft, out_left=*outbytesleft;
 661         uint8 *c = (uint8 *)*outbuf;
 662         const uint8 *uc = (const uint8 *)*inbuf;
 663
 664         while (in_left >= 2 && out_left >= 1) {
 665                 unsigned int codepoint;
 666
 667                 if (uc[1] == 0 && !(uc[0] & 0x80)) {
 668                         /* simplest case */
 669                         c[0] = uc[0];
 670                         in_left  -= 2;
 671                         out_left -= 1;
 672                         uc += 2;
 673                         c  += 1;
 674                         continue;
 675                 }
 676
 677                 if ((uc[1]&0xf8) == 0) {
 678                         /* next simplest case */
 679                         if (out_left < 2) {
 680                                 errno = E2BIG;
 681                                 goto error;
 682                         }
 683                         c[0] = 0xc0 | (uc[0]>>6) | (uc[1]<<2);
 684                         c[1] = 0x80 | (uc[0] & 0x3f);
 685                         in_left  -= 2;
 686                         out_left -= 2;
 687                         uc += 2;
 688                         c  += 2;
 689                         continue;
 690                 }
 691
 692                 if ((uc[1] & 0xfc) == 0xdc) {
 693                         /* its the second part of a 4 byte sequence. Illegal */
 694                         if (in_left < 4) {
 695                                 errno = EINVAL;
 696                         } else {
 697                                 errno = EILSEQ;
 698                         }
 699                         goto error;
 700                 }
 701
 702                 if ((uc[1] & 0xfc) != 0xd8) {
 703                         codepoint = uc[0] | (uc[1]<<8);
 704                         if (out_left < 3) {
 705                                 errno = E2BIG;
 706                                 goto error;
 707                         }
 708                         c[0] = 0xe0 | (codepoint >> 12);
 709                         c[1] = 0x80 | ((codepoint >> 6) & 0x3f);
 710                         c[2] = 0x80 | (codepoint & 0x3f);
 711
 712                         in_left  -= 2;
 713                         out_left -= 3;
 714                         uc  += 2;
 715                         c   += 3;
 716                         continue;
 717                 }
 718
 719                 /* its the first part of a 4 byte sequence */
 720                 if (in_left < 4) {
 721                         errno = EINVAL;
 722                         goto error;
 723                 }
 724                 if ((uc[3] & 0xfc) != 0xdc) {
 725                         errno = EILSEQ;
 726                         goto error;
 727                 }
 728                 codepoint = 0x10000 + (uc[2] | ((uc[3] & 0x3)<<8) |
 729                                        (uc[0]<<10) | ((uc[1] & 0x3)<<18));
 730
 731                 if (out_left < 4) {
 732                         errno = E2BIG;
 733                         goto error;
 734                 }
 735                 c[0] = 0xf0 | (codepoint >> 18);
 736                 c[1] = 0x80 | ((codepoint >> 12) & 0x3f);
 737                 c[2] = 0x80 | ((codepoint >> 6) & 0x3f);
 738                 c[3] = 0x80 | (codepoint & 0x3f);
 739
 740                 in_left  -= 4;
 741                 out_left -= 4;
 742                 uc       += 4;
 743                 c        += 4;
 744         }
 745
 746         if (in_left == 1) {
 747                 errno = EINVAL;
 748                 goto error;
 749         }
 750
 751         if (in_left > 1) {
 752                 errno = E2BIG;
 753                 goto error;
 754         }
 755
 756         *inbytesleft = in_left;
 757         *outbytesleft = out_left;
 758         *inbuf  = uc;
 759         *outbuf = c;
 760
 761         return 0;
 762
 763 error:
 764         *inbytesleft = in_left;
 765         *outbytesleft = out_left;
 766         *inbuf  = uc;
 767         *outbuf = c;
 768         return -1;
 769 }
 770