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) 1997-2012 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-16 character
42strings. */
43
44
45#ifdef HAVE_CONFIG_H
46#include "config.h"
47#endif
48
49/* Generate code with 16 bit character support. */
50#define COMPILE_PCRE16
51
52#include "pcre_internal.h"
53
54
55/*************************************************
56*         Validate a UTF-16 string                *
57*************************************************/
58
59/* This function is called (optionally) at the start of compile or match, to
60check that a supposed UTF-16 string is actually valid. The early check means
61that subsequent code can assume it is dealing with a valid string. The check
62can be turned off for maximum performance, but the consequences of supplying an
63invalid string are then undefined.
64
65From release 8.21 more information about the details of the error are passed
66back in the returned value:
67
68PCRE_UTF16_ERR0  No error
69PCRE_UTF16_ERR1  Missing low surrogate at the end of the string
70PCRE_UTF16_ERR2  Invalid low surrogate
71PCRE_UTF16_ERR3  Isolated low surrogate
72PCRE_UTF16_ERR4  Not allowed character
73
74Arguments:
75  string       points to the string
76  length       length of string, or -1 if the string is zero-terminated
77  errp         pointer to an error position offset variable
78
79Returns:       = 0    if the string is a valid UTF-16 string
80               > 0    otherwise, setting the offset of the bad character
81*/
82
83int
84PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
85{
86#ifdef SUPPORT_UTF
87register PCRE_PUCHAR p;
88register pcre_uchar c;
89
90if (length < 0)
91  {
92  for (p = string; *p != 0; p++);
93  length = p - string;
94  }
95
96for (p = string; length-- > 0; p++)
97  {
98  c = *p;
99
100  if ((c & 0xf800) != 0xd800)
101    {
102    /* Normal UTF-16 code point. Neither high nor low surrogate. */
103
104    /* This is probably a BOM from a different byte-order.
105    Regardless, the string is rejected. */
106    if (c == 0xfffe)
107      {
108      *erroroffset = p - string;
109      return PCRE_UTF16_ERR4;
110      }
111    }
112  else if ((c & 0x0400) == 0)
113    {
114    /* High surrogate. */
115
116    /* Must be a followed by a low surrogate. */
117    if (length == 0)
118      {
119      *erroroffset = p - string;
120      return PCRE_UTF16_ERR1;
121      }
122    p++;
123    length--;
124    if ((*p & 0xfc00) != 0xdc00)
125      {
126      *erroroffset = p - string;
127      return PCRE_UTF16_ERR2;
128      }
129    }
130  else
131    {
132    /* Isolated low surrogate. Always an error. */
133    *erroroffset = p - string;
134    return PCRE_UTF16_ERR3;
135    }
136  }
137
138#else  /* SUPPORT_UTF */
139(void)(string);  /* Keep picky compilers happy */
140(void)(length);
141#endif /* SUPPORT_UTF */
142
143return PCRE_UTF16_ERR0;   /* This indicates success */
144}
145
146/* End of pcre16_valid_utf16.c */
147