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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
77 int
78 _pcre_valid_utf8(USPTR string, int length)
79 {
80 #ifdef SUPPORT_UTF8
81 register USPTR p;
82
83 if (length < 0)
84 {
85 for (p = string; *p != 0; p++);
86 length = p - string;
87 }
88
89 for (p = string; length-- > 0; p++)
90 {
91 register int ab;
92 register int c = *p;
93 if (c < 128) continue;
94 if (c < 0xc0) return p - string;
95 ab = _pcre_utf8_table4[c & 0x3f]; /* Number of additional bytes */
96 if (length < ab || ab > 3) return p - string;
97 length -= ab;
98
99 /* Check top bits in the second byte */
100 if ((*(++p) & 0xc0) != 0x80) return p - string;
101
102 /* Check for overlong sequences for each different length, and for the
103 excluded range 0xd000 to 0xdfff. */
104
105 switch (ab)
106 {
107 /* Check for xx00 000x (overlong sequence) */
108
109 case 1:
110 if ((c & 0x3e) == 0) return p - string;
111 continue; /* We know there aren't any more bytes to check */
112
113 /* Check for 1110 0000, xx0x xxxx (overlong sequence) or
114 1110 1101, 1010 xxxx (0xd000 - 0xdfff) */
115
116 case 2:
117 if ((c == 0xe0 && (*p & 0x20) == 0) ||
118 (c == 0xed && *p >= 0xa0))
119 return p - string;
120 break;
121
122 /* Check for 1111 0000, xx00 xxxx (overlong sequence) or
123 greater than 0x0010ffff (f4 8f bf bf) */
124
125 case 3:
126 if ((c == 0xf0 && (*p & 0x30) == 0) ||
127 (c > 0xf4 ) ||
128 (c == 0xf4 && *p > 0x8f))
129 return p - string;
130 break;
131
132 #if 0
133 /* These cases can no longer occur, as we restrict to a maximum of four
134 bytes nowadays. Leave the code here in case we ever want to add an option
135 for longer sequences. */
136
137 /* Check for 1111 1000, xx00 0xxx */
138 case 4:
139 if (c == 0xf8 && (*p & 0x38) == 0) return p - string;
140 break;
141
142 /* Check for leading 0xfe or 0xff, and then for 1111 1100, xx00 00xx */
143 case 5:
144 if (c == 0xfe || c == 0xff ||
145 (c == 0xfc && (*p & 0x3c) == 0)) return p - string;
146 break;
147 #endif
148
149 }
150
151 /* Check for valid bytes after the 2nd, if any; all must start 10 */
152 while (--ab > 0)
153 {
154 if ((*(++p) & 0xc0) != 0x80) return p - string;
155 }
156 }
157 #else
158 (void)(string); /* Keep picky compilers happy */
159 (void)(length);
160 #endif
161
162 return -1;
163 }
164
165 /* End of pcre_valid_utf8.c */
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