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pcre

    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) 1997-2012 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  Not allowed 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_uchar 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:     /* 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: 
  143: return PCRE_UTF16_ERR0;   /* This indicates success */
  144: }
  145: 
  146: /* End of pcre16_valid_utf16.c */