1 /*
2 * Copyright 2001-2004 Unicode, Inc.
3 *
4 * Disclaimer
5 *
6 * This source code is provided as is by Unicode, Inc. No claims are
7 * made as to fitness for any particular purpose. No warranties of any
8 * kind are expressed or implied. The recipient agrees to determine
9 * applicability of information provided. If this file has been
10 * purchased on magnetic or optical media from Unicode, Inc., the
11 * sole remedy for any claim will be exchange of defective media
12 * within 90 days of receipt.
13 *
14 * Limitations on Rights to Redistribute This Code
15 *
16 * Unicode, Inc. hereby grants the right to freely use the information
17 * supplied in this file in the creation of products supporting the
18 * Unicode Standard, and to make copies of this file in any form
19 * for internal or external distribution as long as this notice
20 * remains attached.
21 */
22
23 /* ---------------------------------------------------------------------
24
25 Conversions between UTF32, UTF-16, and UTF-8. Source code file.
26 Author: Mark E. Davis, 1994.
27 Rev History: Rick McGowan, fixes & updates May 2001.
28 Sept 2001: fixed const & error conditions per
29 mods suggested by S. Parent & A. Lillich.
30 June 2002: Tim Dodd added detection and handling of incomplete
31 source sequences, enhanced error detection, added casts
32 to eliminate compiler warnings.
33 July 2003: slight mods to back out aggressive FFFE detection.
34 Jan 2004: updated switches in from-UTF8 conversions.
35 Oct 2004: updated to use UNI_MAX_LEGAL_UTF32 in UTF-32 conversions.
36
37 See the header file "ConvertUTF.h" for complete documentation.
38
39 ------------------------------------------------------------------------ */
40
41
42 #include "ConvertUTF.h"
43 #ifdef CVTUTF_DEBUG
44 #include <stdio.h>
45 #endif
46
47 static const int halfShift = 10; /* used for shifting by 10 bits */
48
49 static const UTF32 halfBase = 0x0010000UL;
50 static const UTF32 halfMask = 0x3FFUL;
51
52 #define UNI_SUR_HIGH_START (UTF32)0xD800
53 #define UNI_SUR_HIGH_END (UTF32)0xDBFF
54 #define UNI_SUR_LOW_START (UTF32)0xDC00
55 #define UNI_SUR_LOW_END (UTF32)0xDFFF
56 #define false 0
57 #define true 1
58
59 /* --------------------------------------------------------------------- */
60
ConvertUTF32toUTF16(const UTF32 ** sourceStart,const UTF32 * sourceEnd,UTF16 ** targetStart,UTF16 * targetEnd,ConversionFlags flags)61 ConversionResult ConvertUTF32toUTF16 (
62 const UTF32** sourceStart, const UTF32* sourceEnd,
63 UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
64 ConversionResult result = conversionOK;
65 const UTF32* source = *sourceStart;
66 UTF16* target = *targetStart;
67 while (source < sourceEnd) {
68 UTF32 ch;
69 if (target >= targetEnd) {
70 result = targetExhausted; break;
71 }
72 ch = *source++;
73 if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
74 /* UTF-16 surrogate values are illegal in UTF-32; 0xffff or 0xfffe are both reserved values */
75 if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
76 if (flags == strictConversion) {
77 --source; /* return to the illegal value itself */
78 result = sourceIllegal;
79 break;
80 } else {
81 *target++ = UNI_REPLACEMENT_CHAR;
82 }
83 } else {
84 *target++ = (UTF16)ch; /* normal case */
85 }
86 } else if (ch > UNI_MAX_LEGAL_UTF32) {
87 if (flags == strictConversion) {
88 result = sourceIllegal;
89 } else {
90 *target++ = UNI_REPLACEMENT_CHAR;
91 }
92 } else {
93 /* target is a character in range 0xFFFF - 0x10FFFF. */
94 if (target + 1 >= targetEnd) {
95 --source; /* Back up source pointer! */
96 result = targetExhausted; break;
97 }
98 ch -= halfBase;
99 *target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
100 *target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
101 }
102 }
103 *sourceStart = source;
104 *targetStart = target;
105 return result;
106 }
107
108 /* --------------------------------------------------------------------- */
109
ConvertUTF16toUTF32(const UTF16 ** sourceStart,const UTF16 * sourceEnd,UTF32 ** targetStart,UTF32 * targetEnd,ConversionFlags flags)110 ConversionResult ConvertUTF16toUTF32 (
111 const UTF16** sourceStart, const UTF16* sourceEnd,
112 UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
113 ConversionResult result = conversionOK;
114 const UTF16* source = *sourceStart;
115 UTF32* target = *targetStart;
116 UTF32 ch, ch2;
117 while (source < sourceEnd) {
118 const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
119 ch = *source++;
120 /* If we have a surrogate pair, convert to UTF32 first. */
121 if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
122 /* If the 16 bits following the high surrogate are in the source buffer... */
123 if (source < sourceEnd) {
124 ch2 = *source;
125 /* If it's a low surrogate, convert to UTF32. */
126 if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
127 ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
128 + (ch2 - UNI_SUR_LOW_START) + halfBase;
129 ++source;
130 } else if (flags == strictConversion) { /* it's an unpaired high surrogate */
131 --source; /* return to the illegal value itself */
132 result = sourceIllegal;
133 break;
134 }
135 } else { /* We don't have the 16 bits following the high surrogate. */
136 --source; /* return to the high surrogate */
137 result = sourceExhausted;
138 break;
139 }
140 } else if (flags == strictConversion) {
141 /* UTF-16 surrogate values are illegal in UTF-32 */
142 if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
143 --source; /* return to the illegal value itself */
144 result = sourceIllegal;
145 break;
146 }
147 }
148 if (target >= targetEnd) {
149 source = oldSource; /* Back up source pointer! */
150 result = targetExhausted; break;
151 }
152 *target++ = ch;
153 }
154 *sourceStart = source;
155 *targetStart = target;
156 #ifdef CVTUTF_DEBUG
157 if (result == sourceIllegal) {
158 fprintf(stderr, "ConvertUTF16toUTF32 illegal seq 0x%04x,%04x\n", ch, ch2);
159 fflush(stderr);
160 }
161 #endif
162 return result;
163 }
164
165 /* --------------------------------------------------------------------- */
166
167 /*
168 * Index into the table below with the first byte of a UTF-8 sequence to
169 * get the number of trailing bytes that are supposed to follow it.
170 * Note that *legal* UTF-8 values can't have 4 or 5-bytes. The table is
171 * left as-is for anyone who may want to do such conversion, which was
172 * allowed in earlier algorithms.
173 */
174 static const char trailingBytesForUTF8[256] = {
175 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
176 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
177 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
178 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
179 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
180 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
181 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
182 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5
183 };
184
185 /*
186 * Magic values subtracted from a buffer value during UTF8 conversion.
187 * This table contains as many values as there might be trailing bytes
188 * in a UTF-8 sequence.
189 */
190 static const UTF32 offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL,
191 0x03C82080UL, 0xFA082080UL, 0x82082080UL };
192
193 /*
194 * Once the bits are split out into bytes of UTF-8, this is a mask OR-ed
195 * into the first byte, depending on how many bytes follow. There are
196 * as many entries in this table as there are UTF-8 sequence types.
197 * (I.e., one byte sequence, two byte... etc.). Remember that sequencs
198 * for *legal* UTF-8 will be 4 or fewer bytes total.
199 */
200 static const UTF8 firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };
201
202 /* --------------------------------------------------------------------- */
203
204 /* The interface converts a whole buffer to avoid function-call overhead.
205 * Constants have been gathered. Loops & conditionals have been removed as
206 * much as possible for efficiency, in favor of drop-through switches.
207 * (See "Note A" at the bottom of the file for equivalent code.)
208 * If your compiler supports it, the "isLegalUTF8" call can be turned
209 * into an inline function.
210 */
211
212 /* --------------------------------------------------------------------- */
213
ConvertUTF16toUTF8(const UTF16 ** sourceStart,const UTF16 * sourceEnd,UTF8 ** targetStart,UTF8 * targetEnd,ConversionFlags flags)214 ConversionResult ConvertUTF16toUTF8 (
215 const UTF16** sourceStart, const UTF16* sourceEnd,
216 UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
217 ConversionResult result = conversionOK;
218 const UTF16* source = *sourceStart;
219 UTF8* target = *targetStart;
220 while (source < sourceEnd) {
221 UTF32 ch;
222 unsigned short bytesToWrite = 0;
223 const UTF32 byteMask = 0xBF;
224 const UTF32 byteMark = 0x80;
225 const UTF16* oldSource = source; /* In case we have to back up because of target overflow. */
226 ch = *source++;
227 /* If we have a surrogate pair, convert to UTF32 first. */
228 if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) {
229 /* If the 16 bits following the high surrogate are in the source buffer... */
230 if (source < sourceEnd) {
231 UTF32 ch2 = *source;
232 /* If it's a low surrogate, convert to UTF32. */
233 if (ch2 >= UNI_SUR_LOW_START && ch2 <= UNI_SUR_LOW_END) {
234 ch = ((ch - UNI_SUR_HIGH_START) << halfShift)
235 + (ch2 - UNI_SUR_LOW_START) + halfBase;
236 ++source;
237 } else if (flags == strictConversion) { /* it's an unpaired high surrogate */
238 --source; /* return to the illegal value itself */
239 result = sourceIllegal;
240 break;
241 }
242 } else { /* We don't have the 16 bits following the high surrogate. */
243 --source; /* return to the high surrogate */
244 result = sourceExhausted;
245 break;
246 }
247 } else if (flags == strictConversion) {
248 /* UTF-16 surrogate values are illegal in UTF-32 */
249 if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) {
250 --source; /* return to the illegal value itself */
251 result = sourceIllegal;
252 break;
253 }
254 }
255 /* Figure out how many bytes the result will require */
256 if (ch < (UTF32)0x80) { bytesToWrite = 1;
257 } else if (ch < (UTF32)0x800) { bytesToWrite = 2;
258 } else if (ch < (UTF32)0x10000) { bytesToWrite = 3;
259 } else if (ch < (UTF32)0x110000) { bytesToWrite = 4;
260 } else { bytesToWrite = 3;
261 ch = UNI_REPLACEMENT_CHAR;
262 }
263
264 target += bytesToWrite;
265 if (target > targetEnd) {
266 source = oldSource; /* Back up source pointer! */
267 target -= bytesToWrite; result = targetExhausted; break;
268 }
269 switch (bytesToWrite) { /* note: everything falls through. */
270 case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
271 case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
272 case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
273 case 1: *--target = (UTF8)(ch | firstByteMark[bytesToWrite]);
274 }
275 target += bytesToWrite;
276 }
277 *sourceStart = source;
278 *targetStart = target;
279 return result;
280 }
281
282 /* --------------------------------------------------------------------- */
283
284 /*
285 * Utility routine to tell whether a sequence of bytes is legal UTF-8.
286 * This must be called with the length pre-determined by the first byte.
287 * If not calling this from ConvertUTF8to*, then the length can be set by:
288 * length = trailingBytesForUTF8[*source]+1;
289 * and the sequence is illegal right away if there aren't that many bytes
290 * available.
291 * If presented with a length > 4, this returns false. The Unicode
292 * definition of UTF-8 goes up to 4-byte sequences.
293 */
294
isLegalUTF8(const UTF8 * source,int length)295 static Boolean isLegalUTF8(const UTF8 *source, int length) {
296 UTF8 a;
297 const UTF8 *srcptr = source+length;
298 switch (length) {
299 default: return false;
300 /* Everything else falls through when "true"... */
301 case 4: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
302 case 3: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
303 case 2: if ((a = (*--srcptr)) > 0xBF) return false;
304
305 switch (*source) {
306 /* no fall-through in this inner switch */
307 case 0xE0: if (a < 0xA0) return false; break;
308 case 0xED: if (a > 0x9F) return false; break;
309 case 0xF0: if (a < 0x90) return false; break;
310 case 0xF4: if (a > 0x8F) return false; break;
311 default: if (a < 0x80) return false;
312 }
313
314 case 1: if (*source >= 0x80 && *source < 0xC2) return false;
315 }
316 if (*source > 0xF4) return false;
317 return true;
318 }
319
320 /* --------------------------------------------------------------------- */
321
322 /*
323 * Exported function to return whether a UTF-8 sequence is legal or not.
324 * This is not used here; it's just exported.
325 */
isLegalUTF8Sequence(const UTF8 * source,const UTF8 * sourceEnd)326 Boolean isLegalUTF8Sequence(const UTF8 *source, const UTF8 *sourceEnd) {
327 int length = trailingBytesForUTF8[*source]+1;
328 if (source+length > sourceEnd) {
329 return false;
330 }
331 return isLegalUTF8(source, length);
332 }
333
334 /* --------------------------------------------------------------------- */
335
ConvertUTF8toUTF16(const UTF8 ** sourceStart,const UTF8 * sourceEnd,UTF16 ** targetStart,UTF16 * targetEnd,ConversionFlags flags)336 ConversionResult ConvertUTF8toUTF16 (
337 const UTF8** sourceStart, const UTF8* sourceEnd,
338 UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags) {
339 ConversionResult result = conversionOK;
340 const UTF8* source = *sourceStart;
341 UTF16* target = *targetStart;
342 while (source < sourceEnd) {
343 UTF32 ch = 0;
344 unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
345 if (source + extraBytesToRead >= sourceEnd) {
346 result = sourceExhausted; break;
347 }
348 /* Do this check whether lenient or strict */
349 if (! isLegalUTF8(source, extraBytesToRead+1)) {
350 result = sourceIllegal;
351 break;
352 }
353 /*
354 * The cases all fall through. See "Note A" below.
355 */
356 switch (extraBytesToRead) {
357 case 5: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
358 case 4: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
359 case 3: ch += *source++; ch <<= 6;
360 case 2: ch += *source++; ch <<= 6;
361 case 1: ch += *source++; ch <<= 6;
362 case 0: ch += *source++;
363 }
364 ch -= offsetsFromUTF8[extraBytesToRead];
365
366 if (target >= targetEnd) {
367 source -= (extraBytesToRead+1); /* Back up source pointer! */
368 result = targetExhausted; break;
369 }
370 if (ch <= UNI_MAX_BMP) { /* Target is a character <= 0xFFFF */
371 /* UTF-16 surrogate values are illegal in UTF-32 */
372 if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
373 if (flags == strictConversion) {
374 source -= (extraBytesToRead+1); /* return to the illegal value itself */
375 result = sourceIllegal;
376 break;
377 } else {
378 *target++ = UNI_REPLACEMENT_CHAR;
379 }
380 } else {
381 *target++ = (UTF16)ch; /* normal case */
382 }
383 } else if (ch > UNI_MAX_UTF16) {
384 if (flags == strictConversion) {
385 result = sourceIllegal;
386 source -= (extraBytesToRead+1); /* return to the start */
387 break; /* Bail out; shouldn't continue */
388 } else {
389 *target++ = UNI_REPLACEMENT_CHAR;
390 }
391 } else {
392 /* target is a character in range 0xFFFF - 0x10FFFF. */
393 if (target + 1 >= targetEnd) {
394 source -= (extraBytesToRead+1); /* Back up source pointer! */
395 result = targetExhausted; break;
396 }
397 ch -= halfBase;
398 *target++ = (UTF16)((ch >> halfShift) + UNI_SUR_HIGH_START);
399 *target++ = (UTF16)((ch & halfMask) + UNI_SUR_LOW_START);
400 }
401 }
402 *sourceStart = source;
403 *targetStart = target;
404 return result;
405 }
406
407 /* --------------------------------------------------------------------- */
408
ConvertUTF32toUTF8(const UTF32 ** sourceStart,const UTF32 * sourceEnd,UTF8 ** targetStart,UTF8 * targetEnd,ConversionFlags flags)409 ConversionResult ConvertUTF32toUTF8 (
410 const UTF32** sourceStart, const UTF32* sourceEnd,
411 UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags) {
412 ConversionResult result = conversionOK;
413 const UTF32* source = *sourceStart;
414 UTF8* target = *targetStart;
415 while (source < sourceEnd) {
416 UTF32 ch;
417 unsigned short bytesToWrite = 0;
418 const UTF32 byteMask = 0xBF;
419 const UTF32 byteMark = 0x80;
420 ch = *source++;
421 if (flags == strictConversion ) {
422 /* UTF-16 surrogate values are illegal in UTF-32 */
423 if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
424 --source; /* return to the illegal value itself */
425 result = sourceIllegal;
426 break;
427 }
428 }
429 /*
430 * Figure out how many bytes the result will require. Turn any
431 * illegally large UTF32 things (> Plane 17) into replacement chars.
432 */
433 if (ch < (UTF32)0x80) { bytesToWrite = 1;
434 } else if (ch < (UTF32)0x800) { bytesToWrite = 2;
435 } else if (ch < (UTF32)0x10000) { bytesToWrite = 3;
436 } else if (ch <= UNI_MAX_LEGAL_UTF32) { bytesToWrite = 4;
437 } else { bytesToWrite = 3;
438 ch = UNI_REPLACEMENT_CHAR;
439 result = sourceIllegal;
440 }
441
442 target += bytesToWrite;
443 if (target > targetEnd) {
444 --source; /* Back up source pointer! */
445 target -= bytesToWrite; result = targetExhausted; break;
446 }
447 switch (bytesToWrite) { /* note: everything falls through. */
448 case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
449 case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
450 case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
451 case 1: *--target = (UTF8) (ch | firstByteMark[bytesToWrite]);
452 }
453 target += bytesToWrite;
454 }
455 *sourceStart = source;
456 *targetStart = target;
457 return result;
458 }
459
460 /* --------------------------------------------------------------------- */
461
ConvertUTF8toUTF32(const UTF8 ** sourceStart,const UTF8 * sourceEnd,UTF32 ** targetStart,UTF32 * targetEnd,ConversionFlags flags)462 ConversionResult ConvertUTF8toUTF32 (
463 const UTF8** sourceStart, const UTF8* sourceEnd,
464 UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags) {
465 ConversionResult result = conversionOK;
466 const UTF8* source = *sourceStart;
467 UTF32* target = *targetStart;
468 while (source < sourceEnd) {
469 UTF32 ch = 0;
470 unsigned short extraBytesToRead = trailingBytesForUTF8[*source];
471 if (source + extraBytesToRead >= sourceEnd) {
472 result = sourceExhausted; break;
473 }
474 /* Do this check whether lenient or strict */
475 if (! isLegalUTF8(source, extraBytesToRead+1)) {
476 result = sourceIllegal;
477 break;
478 }
479 /*
480 * The cases all fall through. See "Note A" below.
481 */
482 switch (extraBytesToRead) {
483 case 5: ch += *source++; ch <<= 6;
484 case 4: ch += *source++; ch <<= 6;
485 case 3: ch += *source++; ch <<= 6;
486 case 2: ch += *source++; ch <<= 6;
487 case 1: ch += *source++; ch <<= 6;
488 case 0: ch += *source++;
489 }
490 ch -= offsetsFromUTF8[extraBytesToRead];
491
492 if (target >= targetEnd) {
493 source -= (extraBytesToRead+1); /* Back up the source pointer! */
494 result = targetExhausted; break;
495 }
496 if (ch <= UNI_MAX_LEGAL_UTF32) {
497 /*
498 * UTF-16 surrogate values are illegal in UTF-32, and anything
499 * over Plane 17 (> 0x10FFFF) is illegal.
500 */
501 if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_LOW_END) {
502 if (flags == strictConversion) {
503 source -= (extraBytesToRead+1); /* return to the illegal value itself */
504 result = sourceIllegal;
505 break;
506 } else {
507 *target++ = UNI_REPLACEMENT_CHAR;
508 }
509 } else {
510 *target++ = ch;
511 }
512 } else { /* i.e., ch > UNI_MAX_LEGAL_UTF32 */
513 result = sourceIllegal;
514 *target++ = UNI_REPLACEMENT_CHAR;
515 }
516 }
517 *sourceStart = source;
518 *targetStart = target;
519 return result;
520 }
521
522 /* ---------------------------------------------------------------------
523
524 Note A.
525 The fall-through switches in UTF-8 reading code save a
526 temp variable, some decrements & conditionals. The switches
527 are equivalent to the following loop:
528 {
529 int tmpBytesToRead = extraBytesToRead+1;
530 do {
531 ch += *source++;
532 --tmpBytesToRead;
533 if (tmpBytesToRead) ch <<= 6;
534 } while (tmpBytesToRead > 0);
535 }
536 In UTF-8 writing code, the switches on "bytesToWrite" are
537 similarly unrolled loops.
538
539 --------------------------------------------------------------------- */
540