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

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Revision 836 - (show annotations) (download)
Wed Dec 28 17:16:11 2011 UTC (2 years, 10 months ago) by ph10
File MIME type: text/plain
File size: 10131 byte(s)
Merging all the changes from the pcre16 branch into the trunk.

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) 1997-2012 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 returned value:
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 position offset variable
100
101 Returns: = 0 if the string is a valid UTF-8 string
102 > 0 otherwise, setting the offset of the bad character
103 */
104
105 int
106 PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
107 {
108 #ifdef SUPPORT_UTF
109 register PCRE_PUCHAR p;
110
111 if (length < 0)
112 {
113 for (p = string; *p != 0; p++);
114 length = (int)(p - string);
115 }
116
117 for (p = string; length-- > 0; p++)
118 {
119 register int ab, c, d;
120
121 c = *p;
122 if (c < 128) continue; /* ASCII character */
123
124 if (c < 0xc0) /* Isolated 10xx xxxx byte */
125 {
126 *erroroffset = (int)(p - string);
127 return PCRE_UTF8_ERR20;
128 }
129
130 if (c >= 0xfe) /* Invalid 0xfe or 0xff bytes */
131 {
132 *erroroffset = (int)(p - string);
133 return PCRE_UTF8_ERR21;
134 }
135
136 ab = PRIV(utf8_table4)[c & 0x3f]; /* Number of additional bytes */
137 if (length < ab)
138 {
139 *erroroffset = (int)(p - string); /* Missing bytes */
140 return ab - length; /* Codes ERR1 to ERR5 */
141 }
142 length -= ab; /* Length remaining */
143
144 /* Check top bits in the second byte */
145
146 if (((d = *(++p)) & 0xc0) != 0x80)
147 {
148 *erroroffset = (int)(p - string) - 1;
149 return PCRE_UTF8_ERR6;
150 }
151
152 /* For each length, check that the remaining bytes start with the 0x80 bit
153 set and not the 0x40 bit. Then check for an overlong sequence, and for the
154 excluded range 0xd800 to 0xdfff. */
155
156 switch (ab)
157 {
158 /* 2-byte character. No further bytes to check for 0x80. Check first byte
159 for for xx00 000x (overlong sequence). */
160
161 case 1: if ((c & 0x3e) == 0)
162 {
163 *erroroffset = (int)(p - string) - 1;
164 return PCRE_UTF8_ERR15;
165 }
166 break;
167
168 /* 3-byte character. Check third byte for 0x80. Then check first 2 bytes
169 for 1110 0000, xx0x xxxx (overlong sequence) or
170 1110 1101, 1010 xxxx (0xd800 - 0xdfff) */
171
172 case 2:
173 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
174 {
175 *erroroffset = (int)(p - string) - 2;
176 return PCRE_UTF8_ERR7;
177 }
178 if (c == 0xe0 && (d & 0x20) == 0)
179 {
180 *erroroffset = (int)(p - string) - 2;
181 return PCRE_UTF8_ERR16;
182 }
183 if (c == 0xed && d >= 0xa0)
184 {
185 *erroroffset = (int)(p - string) - 2;
186 return PCRE_UTF8_ERR14;
187 }
188 break;
189
190 /* 4-byte character. Check 3rd and 4th bytes for 0x80. Then check first 2
191 bytes for for 1111 0000, xx00 xxxx (overlong sequence), then check for a
192 character greater than 0x0010ffff (f4 8f bf bf) */
193
194 case 3:
195 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
196 {
197 *erroroffset = (int)(p - string) - 2;
198 return PCRE_UTF8_ERR7;
199 }
200 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
201 {
202 *erroroffset = (int)(p - string) - 3;
203 return PCRE_UTF8_ERR8;
204 }
205 if (c == 0xf0 && (d & 0x30) == 0)
206 {
207 *erroroffset = (int)(p - string) - 3;
208 return PCRE_UTF8_ERR17;
209 }
210 if (c > 0xf4 || (c == 0xf4 && d > 0x8f))
211 {
212 *erroroffset = (int)(p - string) - 3;
213 return PCRE_UTF8_ERR13;
214 }
215 break;
216
217 /* 5-byte and 6-byte characters are not allowed by RFC 3629, and will be
218 rejected by the length test below. However, we do the appropriate tests
219 here so that overlong sequences get diagnosed, and also in case there is
220 ever an option for handling these larger code points. */
221
222 /* 5-byte character. Check 3rd, 4th, and 5th bytes for 0x80. Then check for
223 1111 1000, xx00 0xxx */
224
225 case 4:
226 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
227 {
228 *erroroffset = (int)(p - string) - 2;
229 return PCRE_UTF8_ERR7;
230 }
231 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
232 {
233 *erroroffset = (int)(p - string) - 3;
234 return PCRE_UTF8_ERR8;
235 }
236 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
237 {
238 *erroroffset = (int)(p - string) - 4;
239 return PCRE_UTF8_ERR9;
240 }
241 if (c == 0xf8 && (d & 0x38) == 0)
242 {
243 *erroroffset = (int)(p - string) - 4;
244 return PCRE_UTF8_ERR18;
245 }
246 break;
247
248 /* 6-byte character. Check 3rd-6th bytes for 0x80. Then check for
249 1111 1100, xx00 00xx. */
250
251 case 5:
252 if ((*(++p) & 0xc0) != 0x80) /* Third byte */
253 {
254 *erroroffset = (int)(p - string) - 2;
255 return PCRE_UTF8_ERR7;
256 }
257 if ((*(++p) & 0xc0) != 0x80) /* Fourth byte */
258 {
259 *erroroffset = (int)(p - string) - 3;
260 return PCRE_UTF8_ERR8;
261 }
262 if ((*(++p) & 0xc0) != 0x80) /* Fifth byte */
263 {
264 *erroroffset = (int)(p - string) - 4;
265 return PCRE_UTF8_ERR9;
266 }
267 if ((*(++p) & 0xc0) != 0x80) /* Sixth byte */
268 {
269 *erroroffset = (int)(p - string) - 5;
270 return PCRE_UTF8_ERR10;
271 }
272 if (c == 0xfc && (d & 0x3c) == 0)
273 {
274 *erroroffset = (int)(p - string) - 5;
275 return PCRE_UTF8_ERR19;
276 }
277 break;
278 }
279
280 /* Character is valid under RFC 2279, but 4-byte and 5-byte characters are
281 excluded by RFC 3629. The pointer p is currently at the last byte of the
282 character. */
283
284 if (ab > 3)
285 {
286 *erroroffset = (int)(p - string) - ab;
287 return (ab == 4)? PCRE_UTF8_ERR11 : PCRE_UTF8_ERR12;
288 }
289 }
290
291 #else /* SUPPORT_UTF */
292 (void)(string); /* Keep picky compilers happy */
293 (void)(length);
294 #endif
295
296 return PCRE_UTF8_ERR0; /* This indicates success */
297 }
298
299 /* End of pcre_valid_utf8.c */

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