summaryrefslogtreecommitdiffstats
path: root/source3/lib/iconv.c
blob: a6ed429abc8d670be7c89b1cf46c228fa2c422a9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
/* 
   Unix SMB/CIFS implementation.
   minimal iconv implementation
   Copyright (C) Andrew Tridgell 2001
   Copyright (C) Jelmer Vernooij 2002,2003

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

/*
 * We have to use strcasecmp here as the character conversions
 * haven't been initialised yet. JRA.
 */

#undef strcasecmp

/**
 * @file
 *
 * @brief Samba wrapper/stub for iconv character set conversion.
 *
 * iconv is the XPG2 interface for converting between character
 * encodings.  This file provides a Samba wrapper around it, and also
 * a simple reimplementation that is used if the system does not
 * implement iconv.
 *
 * Samba only works with encodings that are supersets of ASCII: ascii
 * characters like whitespace can be tested for directly, multibyte
 * sequences start with a byte with the high bit set, and strings are
 * terminated by a nul byte.
 *
 * Note that the only function provided by iconv is conversion between
 * characters.  It doesn't directly support operations like
 * uppercasing or comparison.  We have to convert to UCS-2 and compare
 * there.
 *
 * @sa Samba Developers Guide
 **/

static_decl_charset;

static size_t ascii_pull(void *,const char **, size_t *, char **, size_t *);
static size_t ascii_push(void *,const char **, size_t *, char **, size_t *);
static size_t latin1_push(void *,const char **, size_t *, char **, size_t *);
static size_t  utf8_pull(void *,const char **, size_t *, char **, size_t *);
static size_t  utf8_push(void *,const char **, size_t *, char **, size_t *);
static size_t ucs2hex_pull(void *,const char **, size_t *, char **, size_t *);
static size_t ucs2hex_push(void *,const char **, size_t *, char **, size_t *);
static size_t iconv_copy(void *,const char **, size_t *, char **, size_t *);
static size_t iconv_swab  (void *,const char **, size_t *, char **, size_t *);

static struct charset_functions builtin_functions[] = {
	/* windows is really neither UCS-2 not UTF-16 */
	{"UCS-2LE",  iconv_copy, iconv_copy},
	{"UTF-16LE",  iconv_copy, iconv_copy},
	{"UCS-2BE",  iconv_swab, iconv_swab},
	{"UTF-16BE",  iconv_swab, iconv_swab},

	/* we include the UTF-8 alias to cope with differing locale settings */
	{"UTF8",   utf8_pull,  utf8_push},
	{"UTF-8",   utf8_pull,  utf8_push},
	{"ASCII", ascii_pull, ascii_push},
	{"646", ascii_pull, ascii_push},
	{"ISO-8859-1", ascii_pull, latin1_push},
	{"UCS2-HEX", ucs2hex_pull, ucs2hex_push},
	{NULL, NULL, NULL}
};

static struct charset_functions *charsets = NULL;

static struct charset_functions *find_charset_functions(const char *name) 
{
	struct charset_functions *c = charsets;

	while(c) {
		if (strcasecmp(name, c->name) == 0) {
			return c;
		}
		c = c->next;
	}

	return NULL;
}

NTSTATUS smb_register_charset(struct charset_functions *funcs) 
{
	if (!funcs) {
		return NT_STATUS_INVALID_PARAMETER;
	}

	DEBUG(5, ("Attempting to register new charset %s\n", funcs->name));
	/* Check whether we already have this charset... */
	if (find_charset_functions(funcs->name)) {
		DEBUG(0, ("Duplicate charset %s, not registering\n", funcs->name));
		return NT_STATUS_OBJECT_NAME_COLLISION;
	}

	funcs->next = funcs->prev = NULL;
	DEBUG(5, ("Registered charset %s\n", funcs->name));
	DLIST_ADD(charsets, funcs);
	return NT_STATUS_OK;
}

static void lazy_initialize_iconv(void)
{
	static bool initialized;
	int i;

	if (!initialized) {
		initialized = True;
		for(i = 0; builtin_functions[i].name; i++) 
			smb_register_charset(&builtin_functions[i]);
		static_init_charset;
	}
}

#ifdef HAVE_NATIVE_ICONV
/* if there was an error then reset the internal state,
   this ensures that we don't have a shift state remaining for
   character sets like SJIS */
static size_t sys_iconv(void *cd, 
			const char **inbuf, size_t *inbytesleft,
			char **outbuf, size_t *outbytesleft)
{
	size_t ret = iconv((iconv_t)cd, 
			   (void *)inbuf, inbytesleft,
			   outbuf, outbytesleft);
	if (ret == (size_t)-1) {
		int saved_errno = errno;
		iconv(cd, NULL, NULL, NULL, NULL);
		errno = saved_errno;
	}
	return ret;
}
#endif

/**
 * This is a simple portable iconv() implementaion.
 *
 * It only knows about a very small number of character sets - just
 * enough that Samba works on systems that don't have iconv.
 **/
size_t smb_iconv(smb_iconv_t cd, 
		 const char **inbuf, size_t *inbytesleft,
		 char **outbuf, size_t *outbytesleft)
{
	char cvtbuf[2048];
	char *bufp = cvtbuf;
	size_t bufsize;

	/* in many cases we can go direct */
	if (cd->direct) {
		return cd->direct(cd->cd_direct, 
				  inbuf, inbytesleft, outbuf, outbytesleft);
	}


	/* otherwise we have to do it chunks at a time */
	while (*inbytesleft > 0) {
		bufp = cvtbuf;
		bufsize = sizeof(cvtbuf);

		if (cd->pull(cd->cd_pull, 
			     inbuf, inbytesleft, &bufp, &bufsize) == -1
		    && errno != E2BIG) return -1;

		bufp = cvtbuf;
		bufsize = sizeof(cvtbuf) - bufsize;

		if (cd->push(cd->cd_push, 
			     (const char **)&bufp, &bufsize, 
			     outbuf, outbytesleft) == -1) return -1;
	}

	return 0;
}


static bool is_utf16(const char *name)
{
	return strcasecmp(name, "UCS-2LE") == 0 ||
		strcasecmp(name, "UTF-16LE") == 0;
}

/*
  simple iconv_open() wrapper
 */
smb_iconv_t smb_iconv_open(const char *tocode, const char *fromcode)
{
	smb_iconv_t ret;
	struct charset_functions *from, *to;

	lazy_initialize_iconv();
	from = charsets;
	to = charsets;

	ret = SMB_MALLOC_P(struct smb_iconv_s);
	if (!ret) {
		errno = ENOMEM;
		return (smb_iconv_t)-1;
	}
	memset(ret, 0, sizeof(struct smb_iconv_s));

	ret->from_name = SMB_STRDUP(fromcode);
	ret->to_name = SMB_STRDUP(tocode);

	/* check for the simplest null conversion */
	if (strcasecmp(fromcode, tocode) == 0) {
		ret->direct = iconv_copy;
		return ret;
	}

	/* check if we have a builtin function for this conversion */
	from = find_charset_functions(fromcode);
	if(from)ret->pull = from->pull;

	to = find_charset_functions(tocode);
	if(to)ret->push = to->push;

	/* check if we can use iconv for this conversion */
#ifdef HAVE_NATIVE_ICONV
	if (!ret->pull) {
		ret->cd_pull = iconv_open("UTF-16LE", fromcode);
		if (ret->cd_pull == (iconv_t)-1)
			ret->cd_pull = iconv_open("UCS-2LE", fromcode);
		if (ret->cd_pull != (iconv_t)-1)
			ret->pull = sys_iconv;
	}

	if (!ret->push) {
		ret->cd_push = iconv_open(tocode, "UTF-16LE");
		if (ret->cd_push == (iconv_t)-1)
			ret->cd_push = iconv_open(tocode, "UCS-2LE");
		if (ret->cd_push != (iconv_t)-1)
			ret->push = sys_iconv;
	}
#endif

	/* check if there is a module available that can do this conversion */
	if (!ret->pull && NT_STATUS_IS_OK(smb_probe_module("charset", fromcode))) {
		if(!(from = find_charset_functions(fromcode)))
			DEBUG(0, ("Module %s doesn't provide charset %s!\n", fromcode, fromcode));
		else 
			ret->pull = from->pull;
	}

	if (!ret->push && NT_STATUS_IS_OK(smb_probe_module("charset", tocode))) {
		if(!(to = find_charset_functions(tocode)))
			DEBUG(0, ("Module %s doesn't provide charset %s!\n", tocode, tocode));
		else 
			ret->push = to->push;
	}

	if (!ret->push || !ret->pull) {
		SAFE_FREE(ret->from_name);
		SAFE_FREE(ret->to_name);
		SAFE_FREE(ret);
		errno = EINVAL;
		return (smb_iconv_t)-1;
	}

	/* check for conversion to/from ucs2 */
	if (is_utf16(fromcode) && to) {
		ret->direct = to->push;
		ret->push = ret->pull = NULL;
		return ret;
	}

	if (is_utf16(tocode) && from) {
		ret->direct = from->pull;
		ret->push = ret->pull = NULL;
		return ret;
	}

	/* Check if we can do the conversion direct */
#ifdef HAVE_NATIVE_ICONV
	if (is_utf16(fromcode)) {
		ret->direct = sys_iconv;
		ret->cd_direct = ret->cd_push;
		ret->cd_push = NULL;
		return ret;
	}
	if (is_utf16(tocode)) {
		ret->direct = sys_iconv;
		ret->cd_direct = ret->cd_pull;
		ret->cd_pull = NULL;
		return ret;
	}
#endif

	return ret;
}

/*
  simple iconv_close() wrapper
*/
int smb_iconv_close (smb_iconv_t cd)
{
#ifdef HAVE_NATIVE_ICONV
	if (cd->cd_direct) iconv_close((iconv_t)cd->cd_direct);
	if (cd->cd_pull) iconv_close((iconv_t)cd->cd_pull);
	if (cd->cd_push) iconv_close((iconv_t)cd->cd_push);
#endif

	SAFE_FREE(cd->from_name);
	SAFE_FREE(cd->to_name);

	memset(cd, 0, sizeof(*cd));
	SAFE_FREE(cd);
	return 0;
}


/**********************************************************************
 the following functions implement the builtin character sets in Samba
 and also the "test" character sets that are designed to test
 multi-byte character set support for english users
***********************************************************************/

static size_t ascii_pull(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	while (*inbytesleft >= 1 && *outbytesleft >= 2) {
		(*outbuf)[0] = (*inbuf)[0];
		(*outbuf)[1] = 0;
		(*inbytesleft)  -= 1;
		(*outbytesleft) -= 2;
		(*inbuf)  += 1;
		(*outbuf) += 2;
	}

	if (*inbytesleft > 0) {
		errno = E2BIG;
		return -1;
	}

	return 0;
}

static size_t ascii_push(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	int ir_count=0;

	while (*inbytesleft >= 2 && *outbytesleft >= 1) {
		(*outbuf)[0] = (*inbuf)[0] & 0x7F;
		if ((*inbuf)[1]) ir_count++;
		(*inbytesleft)  -= 2;
		(*outbytesleft) -= 1;
		(*inbuf)  += 2;
		(*outbuf) += 1;
	}

	if (*inbytesleft == 1) {
		errno = EINVAL;
		return -1;
	}

	if (*inbytesleft > 1) {
		errno = E2BIG;
		return -1;
	}

	return ir_count;
}

static size_t latin1_push(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	int ir_count=0;

	while (*inbytesleft >= 2 && *outbytesleft >= 1) {
		(*outbuf)[0] = (*inbuf)[0];
		if ((*inbuf)[1]) ir_count++;
		(*inbytesleft)  -= 2;
		(*outbytesleft) -= 1;
		(*inbuf)  += 2;
		(*outbuf) += 1;
	}

	if (*inbytesleft == 1) {
		errno = EINVAL;
		return -1;
	}

	if (*inbytesleft > 1) {
		errno = E2BIG;
		return -1;
	}

	return ir_count;
}

static size_t ucs2hex_pull(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	while (*inbytesleft >= 1 && *outbytesleft >= 2) {
		unsigned v;

		if ((*inbuf)[0] != '@') {
			/* seven bit ascii case */
			(*outbuf)[0] = (*inbuf)[0];
			(*outbuf)[1] = 0;
			(*inbytesleft)  -= 1;
			(*outbytesleft) -= 2;
			(*inbuf)  += 1;
			(*outbuf) += 2;
			continue;
		}
		/* it's a hex character */
		if (*inbytesleft < 5) {
			errno = EINVAL;
			return -1;
		}

		if (sscanf(&(*inbuf)[1], "%04x", &v) != 1) {
			errno = EILSEQ;
			return -1;
		}

		(*outbuf)[0] = v&0xff;
		(*outbuf)[1] = v>>8;
		(*inbytesleft)  -= 5;
		(*outbytesleft) -= 2;
		(*inbuf)  += 5;
		(*outbuf) += 2;
	}

	if (*inbytesleft > 0) {
		errno = E2BIG;
		return -1;
	}

	return 0;
}

static size_t ucs2hex_push(void *cd, const char **inbuf, size_t *inbytesleft,
			   char **outbuf, size_t *outbytesleft)
{
	while (*inbytesleft >= 2 && *outbytesleft >= 1) {
		char buf[6];

		if ((*inbuf)[1] == 0 && 
		    ((*inbuf)[0] & 0x80) == 0 &&
		    (*inbuf)[0] != '@') {
			(*outbuf)[0] = (*inbuf)[0];
			(*inbytesleft)  -= 2;
			(*outbytesleft) -= 1;
			(*inbuf)  += 2;
			(*outbuf) += 1;
			continue;
		}
		if (*outbytesleft < 5) {
			errno = E2BIG;
			return -1;
		}
		snprintf(buf, 6, "@%04x", SVAL(*inbuf, 0));
		memcpy(*outbuf, buf, 5);
		(*inbytesleft)  -= 2;
		(*outbytesleft) -= 5;
		(*inbuf)  += 2;
		(*outbuf) += 5;
	}

	if (*inbytesleft == 1) {
		errno = EINVAL;
		return -1;
	}

	if (*inbytesleft > 1) {
		errno = E2BIG;
		return -1;
	}

	return 0;
}

static size_t iconv_swab(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	int n;

	n = MIN(*inbytesleft, *outbytesleft);

	swab(*inbuf, *outbuf, (n&~1));
	if (n&1) {
		(*outbuf)[n-1] = 0;
	}

	(*inbytesleft) -= n;
	(*outbytesleft) -= n;
	(*inbuf) += n;
	(*outbuf) += n;

	if (*inbytesleft > 0) {
		errno = E2BIG;
		return -1;
	}

	return 0;
}

static size_t iconv_copy(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	int n;

	n = MIN(*inbytesleft, *outbytesleft);

	memmove(*outbuf, *inbuf, n);

	(*inbytesleft) -= n;
	(*outbytesleft) -= n;
	(*inbuf) += n;
	(*outbuf) += n;

	if (*inbytesleft > 0) {
		errno = E2BIG;
		return -1;
	}

	return 0;
}

static size_t utf8_pull(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	size_t in_left=*inbytesleft, out_left=*outbytesleft;
	const uint8 *c = (const uint8 *)*inbuf;
	uint8 *uc = (uint8 *)*outbuf;

	while (in_left >= 1 && out_left >= 2) {
		unsigned int codepoint;

		if ((c[0] & 0x80) == 0) {
			uc[0] = c[0];
			uc[1] = 0;
			c  += 1;
			in_left  -= 1;
			out_left -= 2;
			uc += 2;
			continue;
		}

		if ((c[0] & 0xe0) == 0xc0) {
			if (in_left < 2 ||
			    (c[1] & 0xc0) != 0x80) {
				errno = EILSEQ;
				goto error;
			}
			codepoint = (c[1]&0x3f) | ((c[0]&0x1f)<<6);
			if (codepoint < 0x80) {
				/* don't accept UTF-8 characters that are not minimally packed */
				errno = EILSEQ;
				goto error;
			}
			uc[1] = codepoint >> 8;
			uc[0] = codepoint & 0xff;
			c  += 2;
			in_left  -= 2;
			out_left -= 2;
			uc += 2;
			continue;
		}

		if ((c[0] & 0xf0) == 0xe0) {
			if (in_left < 3 ||
			    (c[1] & 0xc0) != 0x80 || 
			    (c[2] & 0xc0) != 0x80) {
				errno = EILSEQ;
				goto error;
			}
			codepoint = (c[2]&0x3f) | ((c[1]&0x3f)<<6) | ((c[0]&0xf)<<12);
			if (codepoint < 0x800) {
				/* don't accept UTF-8 characters that are not minimally packed */
				errno = EILSEQ;
				goto error;
			}
			uc[1] = codepoint >> 8;
			uc[0] = codepoint & 0xff;
			c  += 3;
			in_left  -= 3;
			out_left -= 2;
			uc += 2;
			continue;
		}

		if ((c[0] & 0xf8) == 0xf0) {
			if (in_left < 4 ||
			    (c[1] & 0xc0) != 0x80 || 
			    (c[2] & 0xc0) != 0x80 ||
			    (c[3] & 0xc0) != 0x80) {
				errno = EILSEQ;
				goto error;
			}
			codepoint = 
				(c[3]&0x3f) | 
				((c[2]&0x3f)<<6) | 
				((c[1]&0x3f)<<12) |
				((c[0]&0x7)<<18);
			if (codepoint < 0x10000 || codepoint > 0x10ffff) {
				/* don't accept UTF-8 characters that are not minimally packed */
				errno = EILSEQ;
				goto error;
			}

			codepoint -= 0x10000;

			if (out_left < 4) {
				errno = E2BIG;
				goto error;
			}

			uc[0] = (codepoint>>10) & 0xFF;
			uc[1] = (codepoint>>18) | 0xd8;
			uc[2] = codepoint & 0xFF;
			uc[3] = ((codepoint>>8) & 0x3) | 0xdc;
			c  += 4;
			in_left  -= 4;
			out_left -= 4;
			uc += 4;
			continue;
		}

		/* we don't handle 5 byte sequences */
		errno = EINVAL;
		goto error;
	}

	if (in_left > 0) {
		errno = E2BIG;
		goto error;
	}

	*inbytesleft = in_left;
	*outbytesleft = out_left;
	*inbuf = (char *)c;
	*outbuf = (char *)uc;	
	return 0;

error:
	*inbytesleft = in_left;
	*outbytesleft = out_left;
	*inbuf = (char *)c;
	*outbuf = (char *)uc;
	return -1;
}

static size_t utf8_push(void *cd, const char **inbuf, size_t *inbytesleft,
			char **outbuf, size_t *outbytesleft)
{
	size_t in_left=*inbytesleft, out_left=*outbytesleft;
	uint8 *c = (uint8 *)*outbuf;
	const uint8 *uc = (const uint8 *)*inbuf;

	while (in_left >= 2 && out_left >= 1) {
		unsigned int codepoint;

		if (uc[1] == 0 && !(uc[0] & 0x80)) {
			/* simplest case */
			c[0] = uc[0];
			in_left  -= 2;
			out_left -= 1;
			uc += 2;
			c  += 1;
			continue;
		}

		if ((uc[1]&0xf8) == 0) {
			/* next simplest case */
			if (out_left < 2) {
				errno = E2BIG;
				goto error;
			}
			c[0] = 0xc0 | (uc[0]>>6) | (uc[1]<<2);
			c[1] = 0x80 | (uc[0] & 0x3f);
			in_left  -= 2;
			out_left -= 2;
			uc += 2;
			c  += 2;
			continue;
		}

		if ((uc[1] & 0xfc) == 0xdc) {
			/* its the second part of a 4 byte sequence. Illegal */
			if (in_left < 4) {
				errno = EINVAL;
			} else {
				errno = EILSEQ;
			}
			goto error;
		}

		if ((uc[1] & 0xfc) != 0xd8) {
			codepoint = uc[0] | (uc[1]<<8);
			if (out_left < 3) {
				errno = E2BIG;
				goto error;
			}
			c[0] = 0xe0 | (codepoint >> 12);
			c[1] = 0x80 | ((codepoint >> 6) & 0x3f);
			c[2] = 0x80 | (codepoint & 0x3f);

			in_left  -= 2;
			out_left -= 3;
			uc  += 2;
			c   += 3;
			continue;
		}

		/* its the first part of a 4 byte sequence */
		if (in_left < 4) {
			errno = EINVAL;
			goto error;
		}
		if ((uc[3] & 0xfc) != 0xdc) {
			errno = EILSEQ;
			goto error;
		}
		codepoint = 0x10000 + (uc[2] | ((uc[3] & 0x3)<<8) | 
				       (uc[0]<<10) | ((uc[1] & 0x3)<<18));

		if (out_left < 4) {
			errno = E2BIG;
			goto error;
		}
		c[0] = 0xf0 | (codepoint >> 18);
		c[1] = 0x80 | ((codepoint >> 12) & 0x3f);
		c[2] = 0x80 | ((codepoint >> 6) & 0x3f);
		c[3] = 0x80 | (codepoint & 0x3f);

		in_left  -= 4;
		out_left -= 4;
		uc       += 4;
		c        += 4;
	}

	if (in_left == 1) {
		errno = EINVAL;
		goto error;
	}

	if (in_left > 1) {
		errno = E2BIG;
		goto error;
	}

	*inbytesleft = in_left;
	*outbytesleft = out_left;
	*inbuf  = (char *)uc;
	*outbuf = (char *)c;

	return 0;

error:
	*inbytesleft = in_left;
	*outbytesleft = out_left;
	*inbuf  = (char *)uc;
	*outbuf = (char *)c;
	return -1;
}