1 /*
2 * The authors of this software are Rob Pike and Ken Thompson.
3 * Copyright (c) 2002 by Lucent Technologies.
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose without fee is hereby granted, provided that this entire notice
6 * is included in all copies of any software which is or includes a copy
7 * or modification of this software and in all copies of the supporting
8 * documentation for such software.
9 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
10 * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
11 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
12 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
13 */
14 #include <stdarg.h>
15 #include <string.h>
16 #include "utf.h"
17 #include "utfdef.h"
18
19 enum
20 {
21 Bit1 = 7,
22 Bitx = 6,
23 Bit2 = 5,
24 Bit3 = 4,
25 Bit4 = 3,
26 Bit5 = 2,
27
28 T1 = ((1<<(Bit1+1))-1) ^ 0xFF, /* 0000 0000 */
29 Tx = ((1<<(Bitx+1))-1) ^ 0xFF, /* 1000 0000 */
30 T2 = ((1<<(Bit2+1))-1) ^ 0xFF, /* 1100 0000 */
31 T3 = ((1<<(Bit3+1))-1) ^ 0xFF, /* 1110 0000 */
32 T4 = ((1<<(Bit4+1))-1) ^ 0xFF, /* 1111 0000 */
33 T5 = ((1<<(Bit5+1))-1) ^ 0xFF, /* 1111 1000 */
34
35 Rune1 = (1<<(Bit1+0*Bitx))-1, /* 0000 0000 0111 1111 */
36 Rune2 = (1<<(Bit2+1*Bitx))-1, /* 0000 0111 1111 1111 */
37 Rune3 = (1<<(Bit3+2*Bitx))-1, /* 1111 1111 1111 1111 */
38 Rune4 = (1<<(Bit4+3*Bitx))-1,
39 /* 0001 1111 1111 1111 1111 1111 */
40
41 Maskx = (1<<Bitx)-1, /* 0011 1111 */
42 Testx = Maskx ^ 0xFF, /* 1100 0000 */
43
44 Bad = Runeerror,
45 };
46
47 /*
48 * Modified by Wei-Hwa Huang, Google Inc., on 2004-09-24
49 * This is a slower but "safe" version of the old chartorune
50 * that works on strings that are not necessarily null-terminated.
51 *
52 * If you know for sure that your string is null-terminated,
53 * chartorune will be a bit faster.
54 *
55 * It is guaranteed not to attempt to access "length"
56 * past the incoming pointer. This is to avoid
57 * possible access violations. If the string appears to be
58 * well-formed but incomplete (i.e., to get the whole Rune
59 * we'd need to read past str+length) then we'll set the Rune
60 * to Bad and return 0.
61 *
62 * Note that if we have decoding problems for other
63 * reasons, we return 1 instead of 0.
64 */
65 int
charntorune(Rune * rune,const char * str,int length)66 charntorune(Rune *rune, const char *str, int length)
67 {
68 int c, c1, c2, c3;
69 long l;
70
71 /* When we're not allowed to read anything */
72 if(length <= 0) {
73 goto badlen;
74 }
75
76 /*
77 * one character sequence (7-bit value)
78 * 00000-0007F => T1
79 */
80 c = *(uchar*)str;
81 if(c < Tx) {
82 *rune = c;
83 return 1;
84 }
85
86 // If we can't read more than one character we must stop
87 if(length <= 1) {
88 goto badlen;
89 }
90
91 /*
92 * two character sequence (11-bit value)
93 * 0080-07FF => T2 Tx
94 */
95 c1 = *(uchar*)(str+1) ^ Tx;
96 if(c1 & Testx)
97 goto bad;
98 if(c < T3) {
99 if(c < T2)
100 goto bad;
101 l = ((c << Bitx) | c1) & Rune2;
102 if(l <= Rune1)
103 goto bad;
104 *rune = l;
105 return 2;
106 }
107
108 // If we can't read more than two characters we must stop
109 if(length <= 2) {
110 goto badlen;
111 }
112
113 /*
114 * three character sequence (16-bit value)
115 * 0800-FFFF => T3 Tx Tx
116 */
117 c2 = *(uchar*)(str+2) ^ Tx;
118 if(c2 & Testx)
119 goto bad;
120 if(c < T4) {
121 l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
122 if(l <= Rune2)
123 goto bad;
124 *rune = l;
125 return 3;
126 }
127
128 if (length <= 3)
129 goto badlen;
130
131 /*
132 * four character sequence (21-bit value)
133 * 10000-1FFFFF => T4 Tx Tx Tx
134 */
135 c3 = *(uchar*)(str+3) ^ Tx;
136 if (c3 & Testx)
137 goto bad;
138 if (c < T5) {
139 l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
140 if (l <= Rune3)
141 goto bad;
142 *rune = l;
143 return 4;
144 }
145
146 // Support for 5-byte or longer UTF-8 would go here, but
147 // since we don't have that, we'll just fall through to bad.
148
149 /*
150 * bad decoding
151 */
152 bad:
153 *rune = Bad;
154 return 1;
155 badlen:
156 *rune = Bad;
157 return 0;
158
159 }
160
161
162 /*
163 * This is the older "unsafe" version, which works fine on
164 * null-terminated strings.
165 */
166 int
chartorune(Rune * rune,const char * str)167 chartorune(Rune *rune, const char *str)
168 {
169 int c, c1, c2, c3;
170 long l;
171
172 /*
173 * one character sequence
174 * 00000-0007F => T1
175 */
176 c = *(uchar*)str;
177 if(c < Tx) {
178 *rune = c;
179 return 1;
180 }
181
182 /*
183 * two character sequence
184 * 0080-07FF => T2 Tx
185 */
186 c1 = *(uchar*)(str+1) ^ Tx;
187 if(c1 & Testx)
188 goto bad;
189 if(c < T3) {
190 if(c < T2)
191 goto bad;
192 l = ((c << Bitx) | c1) & Rune2;
193 if(l <= Rune1)
194 goto bad;
195 *rune = l;
196 return 2;
197 }
198
199 /*
200 * three character sequence
201 * 0800-FFFF => T3 Tx Tx
202 */
203 c2 = *(uchar*)(str+2) ^ Tx;
204 if(c2 & Testx)
205 goto bad;
206 if(c < T4) {
207 l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
208 if(l <= Rune2)
209 goto bad;
210 *rune = l;
211 return 3;
212 }
213
214 /*
215 * four character sequence (21-bit value)
216 * 10000-1FFFFF => T4 Tx Tx Tx
217 */
218 c3 = *(uchar*)(str+3) ^ Tx;
219 if (c3 & Testx)
220 goto bad;
221 if (c < T5) {
222 l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
223 if (l <= Rune3)
224 goto bad;
225 *rune = l;
226 return 4;
227 }
228
229 /*
230 * Support for 5-byte or longer UTF-8 would go here, but
231 * since we don't have that, we'll just fall through to bad.
232 */
233
234 /*
235 * bad decoding
236 */
237 bad:
238 *rune = Bad;
239 return 1;
240 }
241
242 int
isvalidcharntorune(const char * str,int length,Rune * rune,int * consumed)243 isvalidcharntorune(const char* str, int length, Rune* rune, int* consumed) {
244 *consumed = charntorune(rune, str, length);
245 return *rune != Runeerror || *consumed == 3;
246 }
247
248 int
runetochar(char * str,const Rune * rune)249 runetochar(char *str, const Rune *rune)
250 {
251 /* Runes are signed, so convert to unsigned for range check. */
252 unsigned long c;
253
254 /*
255 * one character sequence
256 * 00000-0007F => 00-7F
257 */
258 c = *rune;
259 if(c <= Rune1) {
260 str[0] = c;
261 return 1;
262 }
263
264 /*
265 * two character sequence
266 * 0080-07FF => T2 Tx
267 */
268 if(c <= Rune2) {
269 str[0] = T2 | (c >> 1*Bitx);
270 str[1] = Tx | (c & Maskx);
271 return 2;
272 }
273
274 /*
275 * If the Rune is out of range, convert it to the error rune.
276 * Do this test here because the error rune encodes to three bytes.
277 * Doing it earlier would duplicate work, since an out of range
278 * Rune wouldn't have fit in one or two bytes.
279 */
280 if (c > Runemax)
281 c = Runeerror;
282
283 /*
284 * three character sequence
285 * 0800-FFFF => T3 Tx Tx
286 */
287 if (c <= Rune3) {
288 str[0] = T3 | (c >> 2*Bitx);
289 str[1] = Tx | ((c >> 1*Bitx) & Maskx);
290 str[2] = Tx | (c & Maskx);
291 return 3;
292 }
293
294 /*
295 * four character sequence (21-bit value)
296 * 10000-1FFFFF => T4 Tx Tx Tx
297 */
298 str[0] = T4 | (c >> 3*Bitx);
299 str[1] = Tx | ((c >> 2*Bitx) & Maskx);
300 str[2] = Tx | ((c >> 1*Bitx) & Maskx);
301 str[3] = Tx | (c & Maskx);
302 return 4;
303 }
304
305 int
runelen(Rune rune)306 runelen(Rune rune)
307 {
308 char str[10];
309
310 return runetochar(str, &rune);
311 }
312
313 int
runenlen(const Rune * r,int nrune)314 runenlen(const Rune *r, int nrune)
315 {
316 int nb, c;
317
318 nb = 0;
319 while(nrune--) {
320 c = *r++;
321 if (c <= Rune1)
322 nb++;
323 else if (c <= Rune2)
324 nb += 2;
325 else if (c <= Rune3)
326 nb += 3;
327 else /* assert(c <= Rune4) */
328 nb += 4;
329 }
330 return nb;
331 }
332
333 int
fullrune(const char * str,int n)334 fullrune(const char *str, int n)
335 {
336 if (n > 0) {
337 int c = *(uchar*)str;
338 if (c < Tx)
339 return 1;
340 if (n > 1) {
341 if (c < T3)
342 return 1;
343 if (n > 2) {
344 if (c < T4 || n > 3)
345 return 1;
346 }
347 }
348 }
349 return 0;
350 }
351