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Root/pcre/pcre_valid_utf8.c

1/*************************************************
2* Perl-Compatible Regular Expressions *
3*************************************************/
4
5/* PCRE is a library of functions to support regular expressions whose syntax
6and semantics are as close as possible to those of the Perl 5 language.
7
8 Written by Philip Hazel
9 Copyright (c) 1997-2008 University of Cambridge
10
11-----------------------------------------------------------------------------
12Redistribution and use in source and binary forms, with or without
13modification, 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
26THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
27AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
30LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36POSSIBILITY OF SUCH DAMAGE.
37-----------------------------------------------------------------------------
38*/
39
40
41/* This module contains an internal function for validating UTF-8 character
42strings. */
43
44
45#include "pcre_config.h"
46
47#include "pcre_internal.h"
48
49
50/*************************************************
51* Validate a UTF-8 string *
52*************************************************/
53
54/* This function is called (optionally) at the start of compile or match, to
55validate that a supposed UTF-8 string is actually valid. The early check means
56that subsequent code can assume it is dealing with a valid string. The check
57can be turned off for maximum performance, but the consequences of supplying
58an invalid string are then undefined.
59
60Originally, this function checked according to RFC 2279, allowing for values in
61the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
62the canonical format. Once somebody had pointed out RFC 3629 to me (it
63obsoletes 2279), additional restrictions were applied. The values are now
64limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
65subrange 0xd000 to 0xdfff is excluded.
66
67Arguments:
68 string points to the string
69 length length of string, or -1 if the string is zero-terminated
70
71Returns: < 0 if the string is a valid UTF-8 string
72 >= 0 otherwise; the value is the offset of the bad byte
73*/
74
75int
76_pcre_valid_utf8(const uschar *string, int length)
77{
78#ifdef SUPPORT_UTF8
79register const uschar *p;
80
81if (length < 0)
82 {
83 for (p = string; *p != 0; p++);
84 length = p - string;
85 }
86
87for (p = string; length-- > 0; p++)
88 {
89 register int ab;
90 register int c = *p;
91 if (c < 128) continue;
92 if (c < 0xc0) return p - string;
93 ab = _pcre_utf8_table4[c & 0x3f]; /* Number of additional bytes */
94 if (length < ab || ab > 3) return p - string;
95 length -= ab;
96
97 /* Check top bits in the second byte */
98 if ((*(++p) & 0xc0) != 0x80) return p - string;
99
100 /* Check for overlong sequences for each different length, and for the
101 excluded range 0xd000 to 0xdfff. */
102
103 switch (ab)
104 {
105 /* Check for xx00 000x (overlong sequence) */
106
107 case 1:
108 if ((c & 0x3e) == 0) return p - string;
109 continue; /* We know there aren't any more bytes to check */
110
111 /* Check for 1110 0000, xx0x xxxx (overlong sequence) or
112 1110 1101, 1010 xxxx (0xd000 - 0xdfff) */
113
114 case 2:
115 if ((c == 0xe0 && (*p & 0x20) == 0) ||
116 (c == 0xed && *p >= 0xa0))
117 return p - string;
118 break;
119
120 /* Check for 1111 0000, xx00 xxxx (overlong sequence) or
121 greater than 0x0010ffff (f4 8f bf bf) */
122
123 case 3:
124 if ((c == 0xf0 && (*p & 0x30) == 0) ||
125 (c > 0xf4 ) ||
126 (c == 0xf4 && *p > 0x8f))
127 return p - string;
128 break;
129
130#if 0
131 /* These cases can no longer occur, as we restrict to a maximum of four
132 bytes nowadays. Leave the code here in case we ever want to add an option
133 for longer sequences. */
134
135 /* Check for 1111 1000, xx00 0xxx */
136 case 4:
137 if (c == 0xf8 && (*p & 0x38) == 0) return p - string;
138 break;
139
140 /* Check for leading 0xfe or 0xff, and then for 1111 1100, xx00 00xx */
141 case 5:
142 if (c == 0xfe || c == 0xff ||
143 (c == 0xfc && (*p & 0x3c) == 0)) return p - string;
144 break;
145#endif
146
147 }
148
149 /* Check for valid bytes after the 2nd, if any; all must start 10 */
150 while (--ab > 0)
151 {
152 if ((*(++p) & 0xc0) != 0x80) return p - string;
153 }
154 }
155#endif
156
157return -1;
158}
159
160/* End of pcre_valid_utf8.c */

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