-
Notifications
You must be signed in to change notification settings - Fork 0
/
utf-8.c
509 lines (448 loc) · 13.2 KB
/
utf-8.c
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
/* A smattering of UTF-8 smarts intended to be used for dealing display
* content from unknown sources in a UTF-8 setting. For convience, has
* a ISO-8859-1 validator, but not a general purpose UTF-8 or charset
* library.
*
* October 2018, Benjamin Elijah Griffin / Eli the Bearded
*/
/*
* Copyright (c) 2018
* Benjamin Elijah Griffin / Eli the Bearded
*
* Distributed uner the MIT License:
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
*/
/* Bit patterns for legitimate UTF-8:
*
* non-highbit:
* 0bbbbbbb
* two octet highbit:
* 110bbbbb 10bbbbbb
* three octet highbit:
* 1110bbbb 10bbbbbb 10bbbbbb
* four octet highbit:
* 11110bbb 10bbbbbb 10bbbbbb 10bbbbbb
*/
/* low bit (no highbit)
* 0bbbbbbb
* note that null is low bit
*/
#define UTF8_LOWBIT(oct) (0x00 == ((oct) & 0x80))
/* any continuation octet
* 10bbbbbb
*/
#define UTF8_CONTINUATION(oct) (0x80 == ((oct) & 0xC0))
/* start of two octet
* 110bbbbb
*/
#define UTF8_SEQUENCE_2(oct) (0xC0 == ((oct) & 0xE0))
/* start of three octet
* 1110bbbb
*/
#define UTF8_SEQUENCE_3(oct) (0xE0 == ((oct) & 0xF0))
/* start of four octet
* 11110bbb
*/
#define UTF8_SEQUENCE_4(oct) (0xF0 == ((oct) & 0xF8))
#define iequal(a,b,l) (strncasecmp(a,b,l)==0)/* case-insensitive equal */
/* checks a string str of length len for legit UTF-8 bit patterns.
* null will not terminate the string -- those are legit 7bit ASCII.
* returns byte offset of first non-legit sequence or -1 if 100% okay.
*/
int
check_utf8(str, len)
unsigned char* str;
int len;
{
int seq, pos, run, octet;
run = 0;
for(pos = 0; pos < len; pos++) {
octet = str[pos];
/* start of a sequence */
if(run == 0) {
seq = pos;
}
if(UTF8_LOWBIT(octet)) {
if( run != 0 ) {
/* whoops, wanted highbit there */
return seq;
}
continue;
}
if(UTF8_CONTINUATION(octet)) {
if( run ) {
/* one of our expected run */
run --;
continue;
}
/* whoops, not the right spot for this */
return seq;
}
if( run ) {
/* whoops, should have had a continuation octet above */
return seq;
}
if(UTF8_SEQUENCE_2(octet)) {
run = 1; /* one more */
continue;
}
if(UTF8_SEQUENCE_3(octet)) {
run = 2; /* two more */
continue;
}
if(UTF8_SEQUENCE_4(octet)) {
run = 3; /* three more */
continue;
}
/* yikes! fall through! */
return seq;
}
return -1;
} /* check_utf8() */
/* Scan a string (up to len long) looking for a valid start of a UTF-8
* sequence. (Does not check that it is a valid UTF-8 character, but
* just where one could be.) Valid starts are low-bit or non-continuation.
* Useful for figuring out where to start printing when dealing with a
* stream entered somewhere besides the start.
* Returns -1 if none are found or the starting offset.
*/
int
find_start_utf8(str, len)
unsigned char* str;
int len;
{
int i = 0;
while(i < len) {
if(UTF8_LOWBIT(str[i])) {
return i;
}
if(!UTF8_CONTINUATION(str[i])) {
return i;
}
i++;
}
return -1;
} /* find_start_utf8() */
/* Checks a string str of length len for legit ASCII bit patterns.
* Recall ASCII is a strict subset of UTF-8.
* null will not terminate the string -- those are legit 7bit ASCII.
* returns byte offset of first non-legit sequence or -1 if 100% okay.
*/
int
check_ascii(str, len)
unsigned char* str;
int len;
{
int pos;
for(pos = 0; pos < len; pos++) {
if(!UTF8_LOWBIT(str[pos])) {
/* Um, yeah, we wanted everything to be lowbit. */
return pos;
}
}
return -1;
} /* check_ascii() */
/* Checks a string str of length len for legit ISO-8859-1 bit patterns.
* Legit UTF-8 can masquarade as ISO-8859-1, but some things that are
* pawned off as ISO-8859-1 are really Windows-1252 (CP-1252).
* null will not terminate the string -- those are legit 7bit ASCII.
* returns byte offset of first non-legit sequence or -1 if 100% okay.
*/
int
check_8859_1(str, len)
unsigned char* str;
int len;
{
int pos;
for(pos = 0; pos < len; pos++) {
if(!UTF8_LOWBIT(str[pos])) {
/* is it in the control character range? */
if(str[pos] < 160) {
return pos;
}
}
}
return -1;
} /* check_8859_1() */
/* Checks a string str of length len for legit charset bit patterns.
* The charset is a case-insenstive name for a MIME chacter encoding and
* set of characters. The set part is not considered, only the encoding.
* If the charset is one of UTF-8 or ISO-8859-1 (also called ISO-LATIN-1),
* it will be tested against rules for those sets. Everything else is
* checked against the ASCII rules.
* null will not terminate the string -- those are legit 7bit ASCII.
* returns byte offset of first non-legit sequence or -1 if 100% okay.
*/
int
check_charset(charset, str, len)
unsigned char* charset;
unsigned char* str;
int len;
{
/* use a length of one more than the fixed string for these iequal tests */
if(iequal(charset, "UTF-8", 6) || iequal(charset, "UTF8", 5)) {
return check_utf8(str,len);
}
if(iequal(charset, "ISO-8859-1", 11) || iequal(charset, "ISO-LATIN-1", 12)) {
return check_8859_1(str,len);
}
return check_ascii(str,len);
} /* check_charset */
/*
* for a valid utf-8 string str and a desired character count len,
* return the number of bytes from the string to print.
* expects a null terminated utf-8 string, and returns a value
* betweeen len and 4 x len
* or strlen(str) if that's less than len
* or -1 if invalid null-terminated utf-8 is discovered
*/
int
display_length(str, len)
unsigned char* str;
int len;
{
int to_emit = 0;
while(len) {
/* null is lowbit, get this out of the way */
if(*str == 0) { return(to_emit); }
if(UTF8_LOWBIT(*str)) {
str ++;
to_emit ++;
}
else if(UTF8_SEQUENCE_2(*str)) {
str += 2;
to_emit += 2;
}
else if(UTF8_SEQUENCE_3(*str)) {
str += 3;
to_emit += 3;
}
else if(UTF8_SEQUENCE_4(*str)) {
str += 4;
to_emit += 4;
}
else {
/* WHOA! should never happen (if valid null-terminated UTF-8). */
return(-1);
}
len --;
}
return(to_emit);
} /* display_length() */
/* for self tests:
* cc -o utf-8 -D_RUN_TESTS utf-8.c && ./utf-8
*/
#ifdef _RUN_TESTS
#include <stdio.h>
#include <strings.h>
struct tests {
/* a test string */
char *input;
int len; /* length, use 0 to just strlen() it */
/* needed for embeded null tests */
/* and expected return values from each of the checkers. */
int utf8;
int iso;
int ascii;
/* check_charset will try the inputs with different charset settings */
};
struct tests cases[] = {
/* test string len utf iso ascii */
{ "Plain ASCII", 0, -1, -1, -1, },
/* with ellipsis */
{ "windows/cp 1252\205", 0, 15, 15, 15, },
/* with pound sign */
{ "\302\243100, same as in UTF-8 town", 0, -1, -1, 0, },
/* with degree sign */
{ "98\260 in the shade of ISO-8859-1", 0, 2, -1, 2, },
/* check past null */
{ "\3\2\1\0\1\2\3", 8, -1, -1, -1, },
/* check again, with a bad character after the null */
{ "\3\2\1\0\1\2\3\213", 9, 7, 7, 7, },
{ 0, 0, 0, 0 },
};
struct tests *tcase;
int
main(argc, argv)
int argc;
char **argv;
{
int i;
/* measure all the simple test cases */
for (i=0; cases[i].input; i++) {
tcase = &cases[i];
if(0 == tcase->len) {
tcase->len = strlen(tcase->input);
}
}
return ( test_check_ascii() ||
test_check_8859_1() ||
test_check_utf8() ||
test_check_charset() ||
test_display_len() ||
test_find_start_utf8() );
} /* main() */
/* Note: each of g (got) and w (want) are evaluated twice. As a macro,
* instead of a function, we can use this to automatically exit the
* calling function on error.
*/
#define RESULT_CHECK(g, w) { \
if(w == g) { \
printf(" ... good:: expected %d == check output %d\n", w, g); \
} else { \
printf("FAILED: Expected %d but got %d\n", w, g); \
return 1; \
} \
}
int
test_find_start_utf8()
{
struct start_tests {
char* fragment;
int where;
};
struct start_tests stcases[] = {
{ " \360\237\244\246 ", 0 },
{ "\360\237\244\246 ", 0 },
{ "\237\244\246 ", 3 },
{ "\244\246 ", 2 },
{ "\246 ", 1 },
{ " ", 0 },
{ 0, 0 }
};
struct start_tests *tcase;
int i, r;
for (i=0; stcases[i].fragment; i++) {
tcase = &stcases[i];
printf("Checking for start UTF-8: %s\n", tcase->fragment);
r = find_start_utf8(tcase->fragment, 12);
RESULT_CHECK(r, tcase->where);
}
return 0;
}
int
test_check_utf8()
{
int i, r;
for (i=0; cases[i].input; i++) {
tcase = &cases[i];
printf("Checking UTF-8 length(%d): %s\n", tcase->len, tcase->input);
r = check_utf8(tcase->input, tcase->len);
RESULT_CHECK(r, tcase->utf8);
}
return 0;
} /* test_check_utf8() */
int
test_check_8859_1()
{
int i, r;
for (i=0; cases[i].input; i++) {
tcase = &cases[i];
printf("Checking ISO-8859-1 length(%d): %s\n", tcase->len, tcase->input);
r = check_8859_1(tcase->input, tcase->len);
RESULT_CHECK(r, tcase->iso);
}
return 0;
} /* test_check_8859_1() */
int
test_check_ascii()
{
int i, r;
for (i=0; cases[i].input; i++) {
tcase = &cases[i];
printf("Checking ASCII length(%d): %s\n", tcase->len, tcase->input);
r = check_ascii(tcase->input, tcase->len);
RESULT_CHECK(r, tcase->ascii);
}
return 0;
} /* test_check_ascii() */
int
test_check_charset()
{
int i, r;
for (i=0; cases[i].input; i++) {
tcase = &cases[i];
printf("Checking as US-ASCII length(%d): %s\n", tcase->len, tcase->input);
r = check_charset("US-ASCII", tcase->input, tcase->len);
RESULT_CHECK(r, tcase->ascii);
printf("Checking as ISO-LATIN-1 length(%d): %s\n", tcase->len, tcase->input);
r = check_charset("ISO-LATIN-1", tcase->input, tcase->len);
RESULT_CHECK(r, tcase->iso);
printf("Checking as ISO-8859-1 length(%d): %s\n", tcase->len, tcase->input);
r = check_charset("ISO-8859-1", tcase->input, tcase->len);
RESULT_CHECK(r, tcase->iso);
printf("Checking as UTF-8 length(%d): %s\n", tcase->len, tcase->input);
r = check_charset("UTF-8", tcase->input, tcase->len);
RESULT_CHECK(r, tcase->utf8);
}
return 0;
} /* test_check_charset() */
/* This test works a little differently. It takes a string and a display
* length (in characters), then tries to truncate the string to that
* length, and then verifies that the truncated string is still UTF-8.
* So ideally you have a bunch of different length UTF-8 characters in
* the test string, and a bunch of different lengths that would naively
* cut-off mid character.
*/
int
test_display_len()
{
int full, want, use, where, dots;
/* ten characters of Hebrew after some simpler ASCII, then
* a space and U+1F926 FACE PALM
* unsigned char jesus[] = "ASCII was good enough for \327\231\326\260\327\224\327\225\326\271\327\251\326\273\327\201\327\242\326\267 \360\237\244\246";
* Actually that's a bad example since it has combining characters,
* so the dot line doesn't match up.
* Use small caps instead. A mix of 1, 2, 3 and 4 character UTF-8.
*/
unsigned char jesus[] = "ASCII was Good Enough\302\256 for \341\264\212\341\264\207\352\234\261\341\264\234\352\234\261 \360\237\244\246";
#define ENOUGH 80
unsigned char something[ENOUGH];
/* naive string length */
full = strlen(jesus);
if(-1 != (where = check_utf8(jesus, full))) {
printf("Test error source sentence is not UTF-8, at %d\n", where);
}
for(want = 20; want < full; want ++) {
strcpy(something, jesus);
use = display_length(something, want);
if(use < ENOUGH) {
something[use] = 0;
} else {
printf("Test error ENOUGH is not enough (%d not less than %d)\n", use, ENOUGH);
return 2;
}
printf("Using %d of %d octets for %d characters.\n", use, full, want);
if(-1 != (where = check_utf8(something, use))) {
printf("Failed to validate as UTF-8, at %d\n", where);
return(1);
}
puts(something);
dots = want;
while(dots) { putchar('.'); dots --; }
putchar('\n');
if (use >= full) {
break;
}
}
return(0);
} /* test_display_len() */
#endif /* _RUN_TESTS */