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Put in cleanUTF8 function, currently unused but will be adapted for our needs.

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git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@300 48356398-32a2-884e-a903-53898d9a118a
This commit is contained in:
Edward Z. Yang 2006-08-18 20:06:40 +00:00
parent a33cd12f1a
commit 42ba96e2de
1 changed files with 139 additions and 0 deletions
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139
library/HTMLPurifier/Lexer.php
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@ -306,6 +306,145 @@ class HTMLPurifier_Lexer
}
}
/**
* Currently converts UTF8 into an array of Unicode codepoints. (changing)
*
* We're going to convert this into a multi-purpose UTF-8 well-formedness
* checker as well as handler for the control characters that are illegal
* in SGML documents. But *after* we draw up some unit-tests. This means
* that the function, in the end, will not return an array of codepoints
* but a valid UTF8 string, with non-SGML codepoints excluded.
*
* @note Just for reference, the non-SGML code points are 0 to 31 and
* 127 to 159, inclusive.
*
* @note The functionality provided by the original function could be
* implemented with iconv using 'UTF-8//IGNORE', mbstring, or
* even the PCRE modifier 'u', these do not allow us to strip
* control characters or disallowed code points, and the latter
* does not allow invalid UTF8 characters to be ignored.
*
* @note Decomposing the string into Unicode code points is necessary
* because SGML disallows the use of specific code points, not
* necessarily bytes. A naive implementation that simply strtr
* disallowed code points as bytes will break other Unicode
* characters in which using such bytes is valid.
*
* @note Code adapted from utf8ToUnicode by Henri Sivonen and
* hsivonen@iki.fi at <http://iki.fi/hsivonen/php-utf8/> under the
* LGPL license.
*/
function cleanUTF8($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
$out = array();
$len = strlen($str);
for($i = 0; $i < $len; $i++) {
$in = ord($str{$i});
if (0 == $mState) {
// When mState is zero we expect either a US-ASCII character
// or a multi-octet sequence.
if (0 == (0x80 & ($in))) {
// US-ASCII, pass straight through.
$out[] = $in;
$mBytes = 1;
} elseif (0xC0 == (0xE0 & ($in))) {
// First octet of 2 octet sequence
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 0x1F) << 6;
$mState = 1;
$mBytes = 2;
} elseif (0xE0 == (0xF0 & ($in))) {
// First octet of 3 octet sequence
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 0x0F) << 12;
$mState = 2;
$mBytes = 3;
} elseif (0xF0 == (0xF8 & ($in))) {
// First octet of 4 octet sequence
$mUcs4 = ($in);
$mUcs4 = ($mUcs4 & 0x07) << 18;
$mState = 3;
$mBytes = 4;
} elseif (0xF8 == (0xFC & ($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;
$mBytes = 5;
} elseif (0xFC == (0xFE & ($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 |= $tmp;
if (0 == --$mState) {
// End of the multi-octet sequence. mUcs4 now contains
// the final Unicode codepoint to be output
// 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 < $mBytes) ||
// From Unicode 3.2, surrogate characters = illegal
(($mUcs4 & 0xFFFFF800) == 0xD800) ||
// Codepoints outside the Unicode range are illegal
($mUcs4 > 0x10FFFF)
) {
return false;
}
if (0xFEFF != $mUcs4) {
// BOM is legal but we don't want to output it
$out[] = $mUcs4;
}
//initialize UTF8 cache
$mState = 0;
$mUcs4 = 0;
$mBytes = 1;
}
} else {
// ((0xC0 & (*in) != 0x80) && (mState != 0))
*
* Incomplete multi-octet sequence.
*/
return false;
}
}
}
return $out;
}
}
?>