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