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

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Revision 579 - (show annotations)
Wed Nov 24 17:39:25 2010 UTC (8 years, 11 months ago) by ph10
File MIME type: text/plain
File size: 6151 byte(s)
Tidies of documenation and code while preparing for release.
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 validate 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
60 an 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.
68
69 Arguments:
70 string points to the string
71 length length of string, or -1 if the string is zero-terminated
72
73 Returns: < 0 if the string is a valid UTF-8 string
74 >= 0 otherwise; the value is the offset of the bad byte
75
76 Bad bytes can be:
77
78 . An isolated byte whose most significant bits are 0x80, because this
79 can only correctly appear within a UTF-8 character;
80
81 . A byte whose most significant bits are 0xc0, but whose other bits indicate
82 that there are more than 3 additional bytes (i.e. an RFC 2279 starting
83 byte, which is no longer valid under RFC 3629);
84
85 .
86
87 The returned offset may also be equal to the length of the string; this means
88 that one or more bytes is missing from the final UTF-8 character.
89 */
90
91 int
92 _pcre_valid_utf8(USPTR string, int length)
93 {
94 #ifdef SUPPORT_UTF8
95 register USPTR p;
96
97 if (length < 0)
98 {
99 for (p = string; *p != 0; p++);
100 length = p - string;
101 }
102
103 for (p = string; length-- > 0; p++)
104 {
105 register int ab;
106 register int c = *p;
107 if (c < 128) continue;
108 if (c < 0xc0) return p - string;
109 ab = _pcre_utf8_table4[c & 0x3f]; /* Number of additional bytes */
110 if (ab > 3) return p - string; /* Too many for RFC 3629 */
111 if (length < ab) return p + 1 + length - string; /* Missing bytes */
112 length -= ab;
113
114 /* Check top bits in the second byte */
115 if ((*(++p) & 0xc0) != 0x80) return p - string;
116
117 /* Check for overlong sequences for each different length, and for the
118 excluded range 0xd000 to 0xdfff. */
119
120 switch (ab)
121 {
122 /* Check for xx00 000x (overlong sequence) */
123
124 case 1:
125 if ((c & 0x3e) == 0) return p - string;
126 continue; /* We know there aren't any more bytes to check */
127
128 /* Check for 1110 0000, xx0x xxxx (overlong sequence) or
129 1110 1101, 1010 xxxx (0xd000 - 0xdfff) */
130
131 case 2:
132 if ((c == 0xe0 && (*p & 0x20) == 0) ||
133 (c == 0xed && *p >= 0xa0))
134 return p - string;
135 break;
136
137 /* Check for 1111 0000, xx00 xxxx (overlong sequence) or
138 greater than 0x0010ffff (f4 8f bf bf) */
139
140 case 3:
141 if ((c == 0xf0 && (*p & 0x30) == 0) ||
142 (c > 0xf4 ) ||
143 (c == 0xf4 && *p > 0x8f))
144 return p - string;
145 break;
146
147 #if 0
148 /* These cases can no longer occur, as we restrict to a maximum of four
149 bytes nowadays. Leave the code here in case we ever want to add an option
150 for longer sequences. */
151
152 /* Check for 1111 1000, xx00 0xxx */
153 case 4:
154 if (c == 0xf8 && (*p & 0x38) == 0) return p - string;
155 break;
156
157 /* Check for leading 0xfe or 0xff, and then for 1111 1100, xx00 00xx */
158 case 5:
159 if (c == 0xfe || c == 0xff ||
160 (c == 0xfc && (*p & 0x3c) == 0)) return p - string;
161 break;
162 #endif
163
164 }
165
166 /* Check for valid bytes after the 2nd, if any; all must start 10 */
167 while (--ab > 0)
168 {
169 if ((*(++p) & 0xc0) != 0x80) return p - string;
170 }
171 }
172 #else
173 (void)(string); /* Keep picky compilers happy */
174 (void)(length);
175 #endif
176
177 return -1;
178 }
179
180 /* End of pcre_valid_utf8.c */

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