Annotation of win32/pcre/pcre_valid_utf8.c, revision 1.4
1.1 misha 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
1.3 misha 9: Copyright (c) 1997-2009 University of Cambridge
1.1 misha 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
1.4 ! misha 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.
1.1 misha 89: */
90:
91: int
1.3 misha 92: _pcre_valid_utf8(USPTR string, int length)
1.1 misha 93: {
94: #ifdef SUPPORT_UTF8
1.3 misha 95: register USPTR p;
1.1 misha 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 */
1.4 ! misha 110: if (ab > 3) return p - string; /* Too many for RFC 3629 */
! 111: if (length < ab) return p + 1 + length - string; /* Missing bytes */
1.1 misha 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: }
1.2 misha 172: #else
173: (void)(string); /* Keep picky compilers happy */
174: (void)(length);
1.1 misha 175: #endif
176:
177: return -1;
178: }
179:
180: /* End of pcre_valid_utf8.c */
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