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/vendor/pcre/pcre_valid_utf8.c

http://github.com/feyeleanor/RubyGoLightly
C | 165 lines | 61 code | 27 blank | 77 comment | 39 complexity | 94fe6661c82f958f70c2b831c922b786 MD5 | raw file
  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#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
 57validate that a supposed UTF-8 string is actually valid. The early check means
 58that subsequent code can assume it is dealing with a valid string. The check
 59can be turned off for maximum performance, but the consequences of supplying
 60an invalid string are then undefined.
 61
 62Originally, this function checked according to RFC 2279, allowing for values in
 63the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in
 64the canonical format. Once somebody had pointed out RFC 3629 to me (it
 65obsoletes 2279), additional restrictions were applied. The values are now
 66limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the
 67subrange 0xd000 to 0xdfff is excluded.
 68
 69Arguments:
 70  string       points to the string
 71  length       length of string, or -1 if the string is zero-terminated
 72
 73Returns:       < 0    if the string is a valid UTF-8 string
 74               >= 0   otherwise; the value is the offset of the bad byte
 75*/
 76
 77int
 78_pcre_valid_utf8(const uschar *string, int length)
 79{
 80#ifdef SUPPORT_UTF8
 81register const uschar *p;
 82
 83if (length < 0)
 84  {
 85  for (p = string; *p != 0; p++);
 86  length = p - string;
 87  }
 88
 89for (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
162return -1;
163}
164
165/* End of pcre_valid_utf8.c */