/*************************************************

*      Perl-Compatible Regular Expressions       *

*************************************************/

/* PCRE is a library of functions to support regular expressions whose syntax

and semantics are as close as possible to those of the Perl 5 language.

                       Written by Philip Hazel

           Copyright (c) 1997-2008 University of Cambridge

-----------------------------------------------------------------------------

Redistribution and use in source and binary forms, with or without

modification, 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, THE

IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

POSSIBILITY OF SUCH DAMAGE.

-----------------------------------------------------------------------------

*/

/* This module contains an internal function for validating UTF-8 character

strings. */

#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, to

validate that a supposed UTF-8 string is actually valid. The early check means

that subsequent code can assume it is dealing with a valid string. The check

can be turned off for maximum performance, but the consequences of supplying

an invalid string are then undefined.

Originally, this function checked according to RFC 2279, allowing for values in

the range 0 to 0x7fffffff, up to 6 bytes long, but ensuring that they were in

the canonical format. Once somebody had pointed out RFC 3629 to me (it

obsoletes 2279), additional restrictions were applied. The values are now

limited to be between 0 and 0x0010ffff, no more than 4 bytes long, and the

subrange 0xd000 to 0xdfff is excluded.

Arguments:

  string       points to the string

  length       length of string, or -1 if the string is zero-terminated

Returns:       < 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_UTF8

register 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;

    }

  }

#else

(void)(string);  /* Keep picky compilers happy */

(void)(length);

#endif

return -1;

}

/* End of pcre_valid_utf8.c */