pcre16_valid_utf16.c

   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) 1997-2013 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-16 character
  42 strings. */
  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
  60 check that a supposed UTF-16 string is actually valid. The early check means
  61 that subsequent code can assume it is dealing with a valid string. The check
  62 can be turned off for maximum performance, but the consequences of supplying an
  63 invalid string are then undefined.
  64
  65 From release 8.21 more information about the details of the error are passed
  66 back in the returned value:
  67
  68 PCRE_UTF16_ERR0  No error
  69 PCRE_UTF16_ERR1  Missing low surrogate at the end of the string
  70 PCRE_UTF16_ERR2  Invalid low surrogate
  71 PCRE_UTF16_ERR3  Isolated low surrogate
  72 PCRE_UTF16_ERR4  Unused (was non-character)
  73
  74 Arguments:
  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
  79 Returns:       = 0    if the string is a valid UTF-16 string
  80                > 0    otherwise, setting the offset of the bad character
  81 */
  82
  83 int
  84 PRIV(valid_utf)(PCRE_PUCHAR string, int length, int *erroroffset)
  85 {
  86 #ifdef SUPPORT_UTF
  87 register PCRE_PUCHAR p;
  88 register pcre_uint32 c;
  89
  90 if (length < 0)
  91   {
  92   for (p = string; *p != 0; p++);
  93   length = p - string;
  94   }
  95
  96 for (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   else if ((c & 0x0400) == 0)
 105     {
 106     /* High surrogate. Must be a followed by a low surrogate. */
 107     if (length == 0)
 108       {
 109       *erroroffset = p - string;
 110       return PCRE_UTF16_ERR1;
 111       }
 112     p++;
 113     length--;
 114     if ((*p & 0xfc00) != 0xdc00)
 115       {
 116       *erroroffset = p - string;
 117       return PCRE_UTF16_ERR2;
 118       }
 119     }
 120   else
 121     {
 122     /* Isolated low surrogate. Always an error. */
 123     *erroroffset = p - string;
 124     return PCRE_UTF16_ERR3;
 125     }
 126   }
 127
 128 #else  /* SUPPORT_UTF */
 129 (void)(string);  /* Keep picky compilers happy */
 130 (void)(length);
 131 (void)(erroroffset);
 132 #endif /* SUPPORT_UTF */
 133
 134 return PCRE_UTF16_ERR0;   /* This indicates success */
 135 }
 136
 137 /* End of pcre16_valid_utf16.c */