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

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Revision 77 - (show annotations) (download)
Sat Feb 24 21:40:45 2007 UTC (7 years, 7 months ago) by nigel
File MIME type: text/plain
File size: 4477 byte(s)
Load pcre-6.0 into code/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) 1997-2005 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 #include "pcre_internal.h"
46
47
48 /*************************************************
49 * Validate a UTF-8 string *
50 *************************************************/
51
52 /* This function is called (optionally) at the start of compile or match, to
53 validate that a supposed UTF-8 string is actually valid. The early check means
54 that subsequent code can assume it is dealing with a valid string. The check
55 can be turned off for maximum performance, but the consequences of supplying
56 an invalid string are then undefined.
57
58 Arguments:
59 string points to the string
60 length length of string, or -1 if the string is zero-terminated
61
62 Returns: < 0 if the string is a valid UTF-8 string
63 >= 0 otherwise; the value is the offset of the bad byte
64 */
65
66 EXPORT int
67 _pcre_valid_utf8(const uschar *string, int length)
68 {
69 register const uschar *p;
70
71 if (length < 0)
72 {
73 for (p = string; *p != 0; p++);
74 length = p - string;
75 }
76
77 for (p = string; length-- > 0; p++)
78 {
79 register int ab;
80 register int c = *p;
81 if (c < 128) continue;
82 if ((c & 0xc0) != 0xc0) return p - string;
83 ab = _pcre_utf8_table4[c & 0x3f]; /* Number of additional bytes */
84 if (length < ab) return p - string;
85 length -= ab;
86
87 /* Check top bits in the second byte */
88 if ((*(++p) & 0xc0) != 0x80) return p - string;
89
90 /* Check for overlong sequences for each different length */
91 switch (ab)
92 {
93 /* Check for xx00 000x */
94 case 1:
95 if ((c & 0x3e) == 0) return p - string;
96 continue; /* We know there aren't any more bytes to check */
97
98 /* Check for 1110 0000, xx0x xxxx */
99 case 2:
100 if (c == 0xe0 && (*p & 0x20) == 0) return p - string;
101 break;
102
103 /* Check for 1111 0000, xx00 xxxx */
104 case 3:
105 if (c == 0xf0 && (*p & 0x30) == 0) return p - string;
106 break;
107
108 /* Check for 1111 1000, xx00 0xxx */
109 case 4:
110 if (c == 0xf8 && (*p & 0x38) == 0) return p - string;
111 break;
112
113 /* Check for leading 0xfe or 0xff, and then for 1111 1100, xx00 00xx */
114 case 5:
115 if (c == 0xfe || c == 0xff ||
116 (c == 0xfc && (*p & 0x3c) == 0)) return p - string;
117 break;
118 }
119
120 /* Check for valid bytes after the 2nd, if any; all must start 10 */
121 while (--ab > 0)
122 {
123 if ((*(++p) & 0xc0) != 0x80) return p - string;
124 }
125 }
126
127 return -1;
128 }
129
130 /* End of pcre_valid_utf8.c */

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