/[pcre]/code/trunk/pcre_valid_utf8.c
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Contents of /code/trunk/pcre_valid_utf8.c

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Revision 598 - (show annotations)
Sat May 7 15:37:31 2011 UTC (4 years, 3 months ago) by ph10
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Pass back detailed info when UTF-8 check fails at runtime.
1 /*************************************************
2 * Perl-Compatible Regular Expressions *
3 *************************************************/
4
5 /* PCRE is a library of functions to support regular expressions whose syntax
6 and semantics are as close as possible to those of the Perl 5 language.
7
8 Written by Philip Hazel
9 Copyright (c) 1997-2009 University of Cambridge
10
11 -----------------------------------------------------------------------------
12 Redistribution and use in source and binary forms, with or without
13 modification, are permitted provided that the following conditions are met:
14
15 * Redistributions of source code must retain the above copyright notice,
16 this list of conditions and the following disclaimer.
17
18 * Redistributions in binary form must reproduce the above copyright
19 notice, this list of conditions and the following disclaimer in the
20 documentation and/or other materials provided with the distribution.
21
22 * Neither the name of the University of Cambridge nor the names of its
23 contributors may be used to endorse or promote products derived from
24 this software without specific prior written permission.
25
26 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
27 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
30 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 POSSIBILITY OF SUCH DAMAGE.
37 -----------------------------------------------------------------------------
38 */
39
40
41 /* This module contains an internal function for validating UTF-8 character
42 strings. */
43
44
45 #ifdef HAVE_CONFIG_H
46 #include "config.h"
47 #endif
48
49 #include "pcre_internal.h"
50
51
52 /*************************************************
53 * Validate a UTF-8 string *
54 *************************************************/
55
56 /* This function is called (optionally) at the start of compile or match, to
57 check that a supposed UTF-8 string is actually valid. The early check means
58 that subsequent code can assume it is dealing with a valid string. The check
59 can be turned off for maximum performance, but the consequences of supplying an
60 invalid string are then undefined.
61
62 Originally, this function checked according to RFC 2279, allowing for values in
63 the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
64 the canonical format. Once somebody had pointed out RFC 3629 to me (it
65 obsoletes 2279), additional restrictions were applied. The values are now
66 limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
67 subrange 0xd000 to 0xdfff is excluded. However, the format of 5-byte and 6-byte
68 characters is still checked.
69
70 From release 8.13 more information about the details of the error are passed
71 back in the error code:
72
73 PCRE_UTF8_ERR0 No error
74 PCRE_UTF8_ERR1 Missing 1 byte at the end of the string
75 PCRE_UTF8_ERR2 Missing 2 bytes at the end of the string
76 PCRE_UTF8_ERR3 Missing 3 bytes at the end of the string
77 PCRE_UTF8_ERR4 Missing 4 bytes at the end of the string
78 PCRE_UTF8_ERR5 Missing 5 bytes at the end of the string
79 PCRE_UTF8_ERR6 2nd-byte's two top bits are not 0x80
80 PCRE_UTF8_ERR7 3rd-byte's two top bits are not 0x80
81 PCRE_UTF8_ERR8 4th-byte's two top bits are not 0x80
82 PCRE_UTF8_ERR9 5th-byte's two top bits are not 0x80
83 PCRE_UTF8_ERR10 6th-byte's two top bits are not 0x80
84 PCRE_UTF8_ERR11 5-byte character is not permitted by RFC 3629
85 PCRE_UTF8_ERR12 6-byte character is not permitted by RFC 3629
86 PCRE_UTF8_ERR13 4-byte character with value > 0x10ffff is not permitted
87 PCRE_UTF8_ERR14 3-byte character with value 0xd000-0xdfff is not permitted
88 PCRE_UTF8_ERR15 Overlong 2-byte sequence
89 PCRE_UTF8_ERR16 Overlong 3-byte sequence
90 PCRE_UTF8_ERR17 Overlong 4-byte sequence
91 PCRE_UTF8_ERR18 Overlong 5-byte sequence (won't ever occur)
92 PCRE_UTF8_ERR19 Overlong 6-byte sequence (won't ever occur)
93 PCRE_UTF8_ERR20 Isolated 0x80 byte (not within UTF-8 character)
94 PCRE_UTF8_ERR21 Byte with the illegal value 0xfe or 0xff
95
96 Arguments:
97 string points to the string
98 length length of string, or -1 if the string is zero-terminated
99 errp pointer to an error code variable
100
101 Returns: < 0 if the string is a valid UTF-8 string
102 >= 0 otherwise; the value is the offset of the bad character
103 */
104
105 int
106 _pcre_valid_utf8(USPTR string, int length, int *errorcode)
107 {
108 #ifdef SUPPORT_UTF8
109 register USPTR p;
110
111 if (length < 0)
112 {
113 for (p = string; *p != 0; p++);
114 length = p - string;
115 }
116
117 *errorcode = PCRE_UTF8_ERR0;
118
119 for (p = string; length-- > 0; p++)
120 {
121 register int ab, c, d;
122
123 c = *p;
124 if (c < 128) continue; /* ASCII character */
125
126 if (c < 0xc0) /* Isolated 10xx xxxx byte */
127 {
128 *errorcode = PCRE_UTF8_ERR20;
129 return p - string;
130 }
131
132 if (c >= 0xfe) /* Invalid 0xfe or 0xff bytes */
133 {
134 *errorcode = PCRE_UTF8_ERR21;
135 return p - string;
136 }
137
138 ab = _pcre_utf8_table4[c & 0x3f]; /* Number of additional bytes */
139 if (length < ab)
140 {
141 *errorcode = ab - length; /* Codes ERR1 to ERR5 */
142 return p - string; /* Missing bytes */
143 }
144 length -= ab; /* Length remaining */
145
146 /* Check top bits in the second byte */
147
148 if (((d = *(++p)) & 0xc0) != 0x80)
149 {
150 *errorcode = PCRE_UTF8_ERR6;
151 return p - string - 1;
152 }
153
154 /* For each length, check that the remaining bytes start with the 0x80 bit
155 set and not the 0x40 bit. Then check for an overlong sequence, and for the
156 excluded range 0xd800 to 0xdfff. */
157
158 switch (ab)
159 {
160 /* 2-byte character. No further bytes to check for 0x80. Check first byte
161 for for xx00 000x (overlong sequence). */
162
163 case 1: if ((c & 0x3e) == 0)
164 {
165 *errorcode = PCRE_UTF8_ERR15;
166 return p - string - 1;
167 }
168 break;
169
170 /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
171 for 1110 0000, xx0x xxxx (overlong sequence) or
172 1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
173
174 case 2:
175 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
176 {
177 *errorcode = PCRE_UTF8_ERR7;
178 return p - string - 2;
179 }
180 if (c == 0xe0 && (d & 0x20) == 0)
181 {
182 *errorcode = PCRE_UTF8_ERR16;
183 return p - string - 2;
184 }
185 if (c == 0xed && d >= 0xa0)
186 {
187 *errorcode = PCRE_UTF8_ERR14;
188 return p - string - 2;
189 }
190 break;
191
192 /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
193 bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
194 character greater than 0x0010ffff (f4 8f bf bf) */
195
196 case 3:
197 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
198 {
199 *errorcode = PCRE_UTF8_ERR7;
200 return p - string - 2;
201 }
202 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
203 {
204 *errorcode = PCRE_UTF8_ERR8;
205 return p - string - 3;
206 }
207 if (c == 0xf0 && (d & 0x30) == 0)
208 {
209 *errorcode = PCRE_UTF8_ERR17;
210 return p - string - 3;
211 }
212 if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
213 {
214 *errorcode = PCRE_UTF8_ERR13;
215 return p - string - 3;
216 }
217 break;
218
219 /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
220 rejected by the length test below. However, we do the appropriate tests
221 here so that overlong sequences get diagnosed, and also in case there is
222 ever an option for handling these larger code points. */
223
224 /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
225 1111 1000, xx00 0xxx */
226
227 case 4:
228 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
229 {
230 *errorcode = PCRE_UTF8_ERR7;
231 return p - string - 2;
232 }
233 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
234 {
235 *errorcode = PCRE_UTF8_ERR8;
236 return p - string - 3;
237 }
238 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
239 {
240 *errorcode = PCRE_UTF8_ERR9;
241 return p - string - 4;
242 }
243 if (c == 0xf8 && (d & 0x38) == 0)
244 {
245 *errorcode = PCRE_UTF8_ERR18;
246 return p - string - 4;
247 }
248 break;
249
250 /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
251 1111 1100, xx00 00xx. */
252
253 case 5:
254 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
255 {
256 *errorcode = PCRE_UTF8_ERR7;
257 return p - string - 2;
258 }
259 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
260 {
261 *errorcode = PCRE_UTF8_ERR8;
262 return p - string - 3;
263 }
264 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
265 {
266 *errorcode = PCRE_UTF8_ERR9;
267 return p - string - 4;
268 }
269 if ((*(++p) & 0xc0) != 0x80) /* Sixth byte */
270 {
271 *errorcode = PCRE_UTF8_ERR10;
272 return p - string - 5;
273 }
274 if (c == 0xfc && (d & 0x3c) == 0)
275 {
276 *errorcode = PCRE_UTF8_ERR19;
277 return p - string - 5;
278 }
279 break;
280 }
281
282 /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
283 excluded by RFC 3629. The pointer p is currently at the last byte of the
284 character. */
285
286 if (ab > 3)
287 {
288 *errorcode = (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
289 return p - string - ab;
290 }
291 }
292
293 #else /* SUPPORT_UTF8 */
294 (void)(string); /* Keep picky compilers happy */
295 (void)(length);
296 #endif
297
298 return -1; /* This indicates success */
299 }
300
301 /* End of pcre_valid_utf8.c */

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