source: branches/rsr.v5.1.1/web/punbb/include/utf8/utils/validation.php

<?php

/**
* @version $Id: validation.php,v 1.2 2006/02/26 13:20:44 harryf Exp $
* Tools for validing a UTF-8 string is well formed.
* The Original Code is Mozilla Communicator client code.
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
* Ported to PHP by Henri Sivonen (http://hsivonen.iki.fi)
* Slight modifications to fit with phputf8 library by Harry Fuecks (hfuecks gmail com)
* @see http://lxr.mozilla.org/seamonkey/source/intl/uconv/src/nsUTF8ToUnicode.cpp
* @see http://lxr.mozilla.org/seamonkey/source/intl/uconv/src/nsUnicodeToUTF8.cpp
* @see http://hsivonen.iki.fi/php-utf8/
* @package utf8
* @subpackage validation
*/

/**
* Tests a string as to whether it's valid UTF-8 and supported by the
* Unicode standard
* Note: this function has been modified to simple return true or false
* @author <hsivonen@iki.fi>
* @param string UTF-8 encoded string
* @return boolean true if valid
* @see http://hsivonen.iki.fi/php-utf8/
* @see utf8_compliant
* @package utf8
* @subpackage validation
*/
function utf8_is_valid($str)
{
        $mState = 0;    // Cached expected number of octets after the current octet
                                        // until the beginning of the next UTF8 character sequence
        $mUcs4  = 0;    // Cached Unicode character
        $mBytes = 1;    // Cached expected number of octets in the current sequence

        $len = strlen($str);

        for($i = 0; $i < $len; $i++)
        {
                $in = ord($str{$i});

                if ( $mState == 0)
                {
                        // When mState is zero we expect either a US-ASCII character or a multi-octet sequence.
                        if (0 == (0x80 & ($in)))
                        {
                                $mBytes = 1; // US-ASCII, pass straight through
                        }
                        else if (0xC0 == (0xE0 & ($in)))
                        {
                                // First octet of 2 octet sequence
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x1F) << 6;
                                $mState = 1;
                                $mBytes = 2;
                        }
                        else if (0xE0 == (0xF0 & ($in)))
                        {
                                // First octet of 3 octet sequence
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x0F) << 12;
                                $mState = 2;
                                $mBytes = 3;
                        }
                        else if (0xF0 == (0xF8 & ($in)))
                        {
                                // First octet of 4 octet sequence
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x07) << 18;
                                $mState = 3;
                                $mBytes = 4;
                        }
                        else if (0xF8 == (0xFC & ($in)))
                        {
                                /* First octet of 5 octet sequence.
                                *
                                * This is illegal because the encoded codepoint must be either
                                * (a) not the shortest form or
                                * (b) outside the Unicode range of 0-0x10FFFF.
                                * Rather than trying to resynchronize, we will carry on until the end
                                * of the sequence and let the later error handling code catch it.
                                */
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 0x03) << 24;
                                $mState = 4;
                                $mBytes = 5;
                        }
                        else if (0xFC == (0xFE & ($in)))
                        {
                                // First octet of 6 octet sequence, see comments for 5 octet sequence.
                                $mUcs4 = ($in);
                                $mUcs4 = ($mUcs4 & 1) << 30;
                                $mState = 5;
                                $mBytes = 6;
                        }
                        else
                        {
                                // Current octet is neither in the US-ASCII range nor a legal first octet of a multi-octet sequence.
                                return false;
                        }
                }
                else
                {
                        // When mState is non-zero, we expect a continuation of the multi-octet sequence
                        if (0x80 == (0xC0 & ($in)))
                        {
                                // Legal continuation.
                                $shift = ($mState - 1) * 6;
                                $tmp = $in;
                                $tmp = ($tmp & 0x0000003F) << $shift;
                                $mUcs4 |= $tmp;

                                /**
                                * End of the multi-octet sequence. mUcs4 now contains the final
                                * Unicode codepoint to be output
                                */
                                if (0 == --$mState)
                                {
                                        /*
                                        * Check for illegal sequences and codepoints.
                                        */
                                        // From Unicode 3.1, non-shortest form is illegal
                                        if (((2 == $mBytes) && ($mUcs4 < 0x0080)) || ((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
                                        ((4 == $mBytes) && ($mUcs4 < 0x10000)) || (4 < $mBytes) ||
                                        // From Unicode 3.2, surrogate characters are illegal
                                        (($mUcs4 & 0xFFFFF800) == 0xD800) ||
                                        // Codepoints outside the Unicode range are illegal
                                        ($mUcs4 > 0x10FFFF))
                                        {
                                                return FALSE;
                                        }

                                        // Initialize UTF8 cache
                                        $mState = 0;
                                        $mUcs4  = 0;
                                        $mBytes = 1;
                                }
                        }
                        else
                        {
                                /**
                                *((0xC0 & (*in) != 0x80) && (mState != 0))
                                * Incomplete multi-octet sequence.
                                */

                                return false;
                        }
                }
        }

        return true;
}

/**
* Tests whether a string complies as UTF-8. This will be much
* faster than utf8_is_valid, but will pass five and six octet
* UTF-8 sequences, which are not supported by Unicode and
* so cannot be displayed correctly in a browser. In other words
* it is not as strict as utf8_is_valid but it's faster. If you use
* is to validate user input, you place yourself at the risk that
* attackers will be able to inject 5 and 6 byte sequences (which
* may or may not be a significant risk, depending on what you are
* are doing)
* Note: Does not pass five and six octet UTF-8 sequences anymore in
*       in the unit tests.
* @see utf8_is_valid
* @see http://www.php.net/manual/en/reference.pcre.pattern.modifiers.php#54805
* @param string UTF-8 string to check
* @return boolean TRUE if string is valid UTF-8
* @package utf8
* @subpackage validation
*/
function utf8_compliant($str)
{
        if (strlen($str) == 0)
                return true;

        // If even just the first character can be matched, when the /u
        // modifier is used, then it's valid UTF-8. If the UTF-8 is somehow
        // invalid, nothing at all will match, even if the string contains
        // some valid sequences
        return (preg_match('/^.{1}/us', $str, $ar) == 1);
}