/**************************************************      Perl-Compatible Regular Expressions       **************************************************//* PCRE is a library of functions to support regular expressions whose syntaxand semantics are as close as possible to those of the Perl 5 language.                       Written by Philip Hazel           Copyright (c) 1997-2007 University of Cambridge-----------------------------------------------------------------------------Redistribution and use in source and binary forms, with or withoutmodification, are permitted provided that the following conditions are met:    * Redistributions of source code must retain the above copyright notice,      this list of conditions and the following disclaimer.    * Redistributions in binary form must reproduce the above copyright      notice, this list of conditions and the following disclaimer in the      documentation and/or other materials provided with the distribution.    * Neither the name of the University of Cambridge nor the names of its      contributors may be used to endorse or promote products derived from      this software without specific prior written permission.THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THEIMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSEARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BELIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, ORCONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OFSUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESSINTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER INCONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THEPOSSIBILITY OF SUCH DAMAGE.-----------------------------------------------------------------------------*//* This module contains an internal function for validating UTF-8 characterstrings. */#ifdef HAVE_CONFIG_H#include "config.h"#endif#include "pcre_internal.h"/**************************************************         Validate a UTF-8 string                **************************************************//* This function is called (optionally) at the start of compile or match, tovalidate that a supposed UTF-8 string is actually valid. The early check meansthat subsequent code can assume it is dealing with a valid string. The checkcan be turned off for maximum performance, but the consequences of supplyingan invalid string are then undefined.Originally, this function checked according to RFC 2279, allowing for values inthe range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were inthe canonical format. Once somebody had pointed out RFC 3629 to me (itobsoletes 2279), additional restrictions were applies. The values are nowlimited to be between 0 and 0x0010ffff, no more than 4 bytes long, and thesubrange 0xd000 to 0xdfff is excluded.Arguments:  string       points to the string  length       length of string, or -1 if the string is zero-terminatedReturns:       < 0    if the string is a valid UTF-8 string               >= 0   otherwise; the value is the offset of the bad byte*/int_pcre_valid_utf8(const uschar *string, int length){#ifdef SUPPORT_UTF8register const uschar *p;if (length < 0)  {  for (p = string; *p != 0; p++);  length = p - string;  }for (p = string; length-- > 0; p++)  {  register int ab;  register int c = *p;  if (c < 128) continue;  if (c < 0xc0) return p - string;  ab = _pcre_utf8_table4[c & 0x3f];     /* Number of additional bytes */  if (length < ab || ab > 3) return p - string;  length -= ab;  /* Check top bits in the second byte */  if ((*(++p) & 0xc0) != 0x80) return p - string;  /* Check for overlong sequences for each different length, and for the  excluded range 0xd000 to 0xdfff.  */  switch (ab)    {    /* Check for xx00 000x (overlong sequence) */    case 1:    if ((c & 0x3e) == 0) return p - string;    continue;   /* We know there aren't any more bytes to check */    /* Check for 1110 0000, xx0x xxxx (overlong sequence) or                 1110 1101, 1010 xxxx (0xd000 - 0xdfff) */    case 2:    if ((c == 0xe0 && (*p & 0x20) == 0) ||        (c == 0xed && *p >= 0xa0))      return p - string;    break;    /* Check for 1111 0000, xx00 xxxx (overlong sequence) or       greater than 0x0010ffff (f4 8f bf bf) */    case 3:    if ((c == 0xf0 && (*p & 0x30) == 0) ||        (c > 0xf4 ) ||        (c == 0xf4 && *p > 0x8f))      return p - string;    break;#if 0    /* These cases can no longer occur, as we restrict to a maximum of four    bytes nowadays. Leave the code here in case we ever want to add an option    for longer sequences. */    /* Check for 1111 1000, xx00 0xxx */    case 4:    if (c == 0xf8 && (*p & 0x38) == 0) return p - string;    break;    /* Check for leading 0xfe or 0xff, and then for 1111 1100, xx00 00xx */    case 5:    if (c == 0xfe || c == 0xff ||       (c == 0xfc && (*p & 0x3c) == 0)) return p - string;    break;#endif    }  /* Check for valid bytes after the 2nd, if any; all must start 10 */  while (--ab > 0)    {    if ((*(++p) & 0xc0) != 0x80) return p - string;    }  }#endifreturn -1;}/* End of pcre_valid_utf8.c */