Merge pull request #481 from wallabag/dev1.5.2

1.5.2
author: Nicolas Lœuillet <nicolas@loeuillet.org> 2014-02-21 15:57:10 +0100
committer: Nicolas Lœuillet <nicolas@loeuillet.org> 2014-02-21 15:57:10 +0100
commit: 99679d06884120c57f43b44e55e03595f1f87bed (patch)
tree: a3f2a1aa1afdaeca1386d0c6e8a75344fd2241fb /inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php
parent: 655214ab30ee84884dc408488b85586f36263fcb (diff)
parent: d3b47e94705e17b3ba3529cbb1dc6efe69c5d2b7 (diff)
download: wallabag-99679d06884120c57f43b44e55e03595f1f87bed.tar.gz
wallabag-99679d06884120c57f43b44e55e03595f1f87bed.tar.zst
wallabag-99679d06884120c57f43b44e55e03595f1f87bed.zip
1 files changed, 611 insertions, 0 deletions
diff --git a/inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php b/inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php
new file mode 100644
index 00000000..3aa00ca5
--- /dev/null
+++ b/inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php
@@ -0,0 +1,611 @@
+<?php
+/**
+ * A UTF-8 specific character encoder that handles cleaning and transforming.
+ * @note All functions in this class should be static.
+ */
+class HTMLPurifier_Encoder
+{
+    /**
+     * Constructor throws fatal error if you attempt to instantiate class
+     */
+    private function __construct()
+    {
+        trigger_error('Cannot instantiate encoder, call methods statically', E_USER_ERROR);
+    }
+    /**
+     * Error-handler that mutes errors, alternative to shut-up operator.
+     */
+    public static function muteErrorHandler()
+    {
+    }
+    /**
+     * iconv wrapper which mutes errors, but doesn't work around bugs.
+     * @param string $in Input encoding
+     * @param string $out Output encoding
+     * @param string $text The text to convert
+     * @return string
+     */
+    public static function unsafeIconv($in, $out, $text)
+    {
+        set_error_handler(array('HTMLPurifier_Encoder', 'muteErrorHandler'));
+        $r = iconv($in, $out, $text);
+        restore_error_handler();
+        return $r;
+    }
+    /**
+     * iconv wrapper which mutes errors and works around bugs.
+     * @param string $in Input encoding
+     * @param string $out Output encoding
+     * @param string $text The text to convert
+     * @param int $max_chunk_size
+     * @return string
+     */
+    public static function iconv($in, $out, $text, $max_chunk_size = 8000)
+    {
+        $code = self::testIconvTruncateBug();
+        if ($code == self::ICONV_OK) {
+            return self::unsafeIconv($in, $out, $text);
+        } elseif ($code == self::ICONV_TRUNCATES) {
+            // we can only work around this if the input character set
+            // is utf-8
+            if ($in == 'utf-8') {
+                if ($max_chunk_size < 4) {
+                    trigger_error('max_chunk_size is too small', E_USER_WARNING);
+                    return false;
+                }
+                // split into 8000 byte chunks, but be careful to handle
+                // multibyte boundaries properly
+                if (($c = strlen($text)) <= $max_chunk_size) {
+                    return self::unsafeIconv($in, $out, $text);
+                }
+                $r = '';
+                $i = 0;
+                while (true) {
+                    if ($i + $max_chunk_size >= $c) {
+                        $r .= self::unsafeIconv($in, $out, substr($text, $i));
+                        break;
+                    }
+                    // wibble the boundary
+                    if (0x80 != (0xC0 & ord($text[$i + $max_chunk_size]))) {
+                        $chunk_size = $max_chunk_size;
+                    } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 1]))) {
+                        $chunk_size = $max_chunk_size - 1;
+                    } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 2]))) {
+                        $chunk_size = $max_chunk_size - 2;
+                    } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 3]))) {
+                        $chunk_size = $max_chunk_size - 3;
+                    } else {
+                        return false; // rather confusing UTF-8...
+                    }
+                    $chunk = substr($text, $i, $chunk_size); // substr doesn't mind overlong lengths
+                    $r .= self::unsafeIconv($in, $out, $chunk);
+                    $i += $chunk_size;
+                }
+                return $r;
+            } else {
+                return false;
+            }
+        } else {
+            return false;
+        }
+    }
+    /**
+     * Cleans a UTF-8 string for well-formedness and SGML validity
+     *
+     * It will parse according to UTF-8 and return a valid UTF8 string, with
+     * non-SGML codepoints excluded.
+     *
+     * @param string $str The string to clean
+     * @param bool $force_php
+     * @return string
+     *
+     * @note Just for reference, the non-SGML code points are 0 to 31 and
+     *       127 to 159, inclusive.  However, we allow code points 9, 10
+     *       and 13, which are the tab, line feed and carriage return
+     *       respectively. 128 and above the code points map to multibyte
+     *       UTF-8 representations.
+     *
+     * @note Fallback code adapted from utf8ToUnicode by Henri Sivonen and
+     *       hsivonen@iki.fi at <http://iki.fi/hsivonen/php-utf8/> under the
+     *       LGPL license.  Notes on what changed are inside, but in general,
+     *       the original code transformed UTF-8 text into an array of integer
+     *       Unicode codepoints. Understandably, transforming that back to
+     *       a string would be somewhat expensive, so the function was modded to
+     *       directly operate on the string.  However, this discourages code
+     *       reuse, and the logic enumerated here would be useful for any
+     *       function that needs to be able to understand UTF-8 characters.
+     *       As of right now, only smart lossless character encoding converters
+     *       would need that, and I'm probably not going to implement them.
+     *       Once again, PHP 6 should solve all our problems.
+     */
+    public static function cleanUTF8($str, $force_php = false)
+    {
+        // UTF-8 validity is checked since PHP 4.3.5
+        // This is an optimization: if the string is already valid UTF-8, no
+        // need to do PHP stuff. 99% of the time, this will be the case.
+        // The regexp matches the XML char production, as well as well as excluding
+        // non-SGML codepoints U+007F to U+009F
+        if (preg_match(
+            '/^[\x{9}\x{A}\x{D}\x{20}-\x{7E}\x{A0}-\x{D7FF}\x{E000}-\x{FFFD}\x{10000}-\x{10FFFF}]*$/Du',
+            $str
+        )) {
+            return $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
+        // original code involved an $out that was an array of Unicode
+        // codepoints.  Instead of having to convert back into UTF-8, we've
+        // decided to directly append valid UTF-8 characters onto a string
+        // $out once they're done.  $char accumulates raw bytes, while $mUcs4
+        // turns into the Unicode code point, so there's some redundancy.
+        $out = '';
+        $char = '';
+        $len = strlen($str);
+        for ($i = 0; $i < $len; $i++) {
+            $in = ord($str{$i});
+            $char .= $str[$i]; // append byte to char
+            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.
+                    if (($in <= 31 || $in == 127) &&
+                        !($in == 9 || $in == 13 || $in == 10) // save \r\t\n
+                    ) {
+                        // control characters, remove
+                    } else {
+                        $out .= $char;
+                    }
+                    // reset
+                    $char = '';
+                    $mBytes = 1;
+                } elseif (0xC0 == (0xE0 & ($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.
+                    $mState = 0;
+                    $mUcs4  = 0;
+                    $mBytes = 1;
+                    $char = '';
+                }
+            } else {
+                // When mState is non-zero, we expect a continuation of the
+                // multi-octet sequence
+                if (0x80 == (0xC0 & ($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)
+                        ) {
+                        } elseif (0xFEFF != $mUcs4 && // omit BOM
+                            // check for valid Char unicode codepoints
+                            (
+                                0x9 == $mUcs4 ||
+                                0xA == $mUcs4 ||
+                                0xD == $mUcs4 ||
+                                (0x20 <= $mUcs4 && 0x7E >= $mUcs4) ||
+                                // 7F-9F is not strictly prohibited by XML,
+                                // but it is non-SGML, and thus we don't allow it
+                                (0xA0 <= $mUcs4 && 0xD7FF >= $mUcs4) ||
+                                (0x10000 <= $mUcs4 && 0x10FFFF >= $mUcs4)
+                            )
+                        ) {
+                            $out .= $char;
+                        }
+                        // initialize UTF8 cache (reset)
+                        $mState = 0;
+                        $mUcs4  = 0;
+                        $mBytes = 1;
+                        $char = '';
+                    }
+                } else {
+                    // ((0xC0 & (*in) != 0x80) && (mState != 0))
+                    // Incomplete multi-octet sequence.
+                    // used to result in complete fail, but we'll reset
+                    $mState = 0;
+                    $mUcs4  = 0;
+                    $mBytes = 1;
+                    $char ='';
+                }
+            }
+        }
+        return $out;
+    }
+    /**
+     * Translates a Unicode codepoint into its corresponding UTF-8 character.
+     * @note Based on Feyd's function at
+     *       <http://forums.devnetwork.net/viewtopic.php?p=191404#191404>,
+     *       which is in public domain.
+     * @note While we're going to do code point parsing anyway, a good
+     *       optimization would be to refuse to translate code points that
+     *       are non-SGML characters.  However, this could lead to duplication.
+     * @note This is very similar to the unichr function in
+     *       maintenance/generate-entity-file.php (although this is superior,
+     *       due to its sanity checks).
+     */
+    // +----------+----------+----------+----------+
+    // | 33222222 | 22221111 | 111111   |          |
+    // | 10987654 | 32109876 | 54321098 | 76543210 | bit
+    // +----------+----------+----------+----------+
+    // |          |          |          | 0xxxxxxx | 1 byte 0x00000000..0x0000007F
+    // |          |          | 110yyyyy | 10xxxxxx | 2 byte 0x00000080..0x000007FF
+    // |          | 1110zzzz | 10yyyyyy | 10xxxxxx | 3 byte 0x00000800..0x0000FFFF
+    // | 11110www | 10wwzzzz | 10yyyyyy | 10xxxxxx | 4 byte 0x00010000..0x0010FFFF
+    // +----------+----------+----------+----------+
+    // | 00000000 | 00011111 | 11111111 | 11111111 | Theoretical upper limit of legal scalars: 2097151 (0x001FFFFF)
+    // | 00000000 | 00010000 | 11111111 | 11111111 | Defined upper limit of legal scalar codes
+    // +----------+----------+----------+----------+
+    public static function unichr($code)
+    {
+        if ($code > 1114111 or $code < 0 or
+          ($code >= 55296 and $code <= 57343) ) {
+            // bits are set outside the "valid" range as defined
+            // by UNICODE 4.1.0
+            return '';
+        }
+        $x = $y = $z = $w = 0;
+        if ($code < 128) {
+            // regular ASCII character
+            $x = $code;
+        } else {
+            // set up bits for UTF-8
+            $x = ($code & 63) | 128;
+            if ($code < 2048) {
+                $y = (($code & 2047) >> 6) | 192;
+            } else {
+                $y = (($code & 4032) >> 6) | 128;
+                if ($code < 65536) {
+                    $z = (($code >> 12) & 15) | 224;
+                } else {
+                    $z = (($code >> 12) & 63) | 128;
+                    $w = (($code >> 18) & 7)  | 240;
+                }
+            }
+        }
+        // set up the actual character
+        $ret = '';
+        if ($w) {
+            $ret .= chr($w);
+        }
+        if ($z) {
+            $ret .= chr($z);
+        }
+        if ($y) {
+            $ret .= chr($y);
+        }
+        $ret .= chr($x);
+        return $ret;
+    }
+    /**
+     * @return bool
+     */
+    public static function iconvAvailable()
+    {
+        static $iconv = null;
+        if ($iconv === null) {
+            $iconv = function_exists('iconv') && self::testIconvTruncateBug() != self::ICONV_UNUSABLE;
+        }
+        return $iconv;
+    }
+    /**
+     * Convert a string to UTF-8 based on configuration.
+     * @param string $str The string to convert
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return string
+     */
+    public static function convertToUTF8($str, $config, $context)
+    {
+        $encoding = $config->get('Core.Encoding');
+        if ($encoding === 'utf-8') {
+            return $str;
+        }
+        static $iconv = null;
+        if ($iconv === null) {
+            $iconv = self::iconvAvailable();
+        }
+        if ($iconv && !$config->get('Test.ForceNoIconv')) {
+            // unaffected by bugs, since UTF-8 support all characters
+            $str = self::unsafeIconv($encoding, 'utf-8//IGNORE', $str);
+            if ($str === false) {
+                // $encoding is not a valid encoding
+                trigger_error('Invalid encoding ' . $encoding, E_USER_ERROR);
+                return '';
+            }
+            // If the string is bjorked by Shift_JIS or a similar encoding
+            // that doesn't support all of ASCII, convert the naughty
+            // characters to their true byte-wise ASCII/UTF-8 equivalents.
+            $str = strtr($str, self::testEncodingSupportsASCII($encoding));
+            return $str;
+        } elseif ($encoding === 'iso-8859-1') {
+            $str = utf8_encode($str);
+            return $str;
+        }
+        $bug = HTMLPurifier_Encoder::testIconvTruncateBug();
+        if ($bug == self::ICONV_OK) {
+            trigger_error('Encoding not supported, please install iconv', E_USER_ERROR);
+        } else {
+            trigger_error(
+                'You have a buggy version of iconv, see https://bugs.php.net/bug.php?id=48147 ' .
+                'and http://sourceware.org/bugzilla/show_bug.cgi?id=13541',
+                E_USER_ERROR
+            );
+        }
+    }
+    /**
+     * Converts a string from UTF-8 based on configuration.
+     * @param string $str The string to convert
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return string
+     * @note Currently, this is a lossy conversion, with unexpressable
+     *       characters being omitted.
+     */
+    public static function convertFromUTF8($str, $config, $context)
+    {
+        $encoding = $config->get('Core.Encoding');
+        if ($escape = $config->get('Core.EscapeNonASCIICharacters')) {
+            $str = self::convertToASCIIDumbLossless($str);
+        }
+        if ($encoding === 'utf-8') {
+            return $str;
+        }
+        static $iconv = null;
+        if ($iconv === null) {
+            $iconv = self::iconvAvailable();
+        }
+        if ($iconv && !$config->get('Test.ForceNoIconv')) {
+            // Undo our previous fix in convertToUTF8, otherwise iconv will barf
+            $ascii_fix = self::testEncodingSupportsASCII($encoding);
+            if (!$escape && !empty($ascii_fix)) {
+                $clear_fix = array();
+                foreach ($ascii_fix as $utf8 => $native) {
+                    $clear_fix[$utf8] = '';
+                }
+                $str = strtr($str, $clear_fix);
+            }
+            $str = strtr($str, array_flip($ascii_fix));
+            // Normal stuff
+            $str = self::iconv('utf-8', $encoding . '//IGNORE', $str);
+            return $str;
+        } elseif ($encoding === 'iso-8859-1') {
+            $str = utf8_decode($str);
+            return $str;
+        }
+        trigger_error('Encoding not supported', E_USER_ERROR);
+        // You might be tempted to assume that the ASCII representation
+        // might be OK, however, this is *not* universally true over all
+        // encodings.  So we take the conservative route here, rather
+        // than forcibly turn on %Core.EscapeNonASCIICharacters
+    }
+    /**
+     * Lossless (character-wise) conversion of HTML to ASCII
+     * @param string $str UTF-8 string to be converted to ASCII
+     * @return string ASCII encoded string with non-ASCII character entity-ized
+     * @warning Adapted from MediaWiki, claiming fair use: this is a common
+     *       algorithm. If you disagree with this license fudgery,
+     *       implement it yourself.
+     * @note Uses decimal numeric entities since they are best supported.
+     * @note This is a DUMB function: it has no concept of keeping
+     *       character entities that the projected character encoding
+     *       can allow. We could possibly implement a smart version
+     *       but that would require it to also know which Unicode
+     *       codepoints the charset supported (not an easy task).
+     * @note Sort of with cleanUTF8() but it assumes that $str is
+     *       well-formed UTF-8
+     */
+    public static function convertToASCIIDumbLossless($str)
+    {
+        $bytesleft = 0;
+        $result = '';
+        $working = 0;
+        $len = strlen($str);
+        for ($i = 0; $i < $len; $i++) {
+            $bytevalue = ord($str[$i]);
+            if ($bytevalue <= 0x7F) { //0xxx xxxx
+                $result .= chr($bytevalue);
+                $bytesleft = 0;
+            } elseif ($bytevalue <= 0xBF) { //10xx xxxx
+                $working = $working << 6;
+                $working += ($bytevalue & 0x3F);
+                $bytesleft--;
+                if ($bytesleft <= 0) {
+                    $result .= "&#" . $working . ";";
+                }
+            } elseif ($bytevalue <= 0xDF) { //110x xxxx
+                $working = $bytevalue & 0x1F;
+                $bytesleft = 1;
+            } elseif ($bytevalue <= 0xEF) { //1110 xxxx
+                $working = $bytevalue & 0x0F;
+                $bytesleft = 2;
+            } else { //1111 0xxx
+                $working = $bytevalue & 0x07;
+                $bytesleft = 3;
+            }
+        }
+        return $result;
+    }
+    /** No bugs detected in iconv. */
+    const ICONV_OK = 0;
+    /** Iconv truncates output if converting from UTF-8 to another
+     *  character set with //IGNORE, and a non-encodable character is found */
+    const ICONV_TRUNCATES = 1;
+    /** Iconv does not support //IGNORE, making it unusable for
+     *  transcoding purposes */
+    const ICONV_UNUSABLE = 2;
+    /**
+     * glibc iconv has a known bug where it doesn't handle the magic
+     * //IGNORE stanza correctly.  In particular, rather than ignore
+     * characters, it will return an EILSEQ after consuming some number
+     * of characters, and expect you to restart iconv as if it were
+     * an E2BIG.  Old versions of PHP did not respect the errno, and
+     * returned the fragment, so as a result you would see iconv
+     * mysteriously truncating output. We can work around this by
+     * manually chopping our input into segments of about 8000
+     * characters, as long as PHP ignores the error code.  If PHP starts
+     * paying attention to the error code, iconv becomes unusable.
+     *
+     * @return int Error code indicating severity of bug.
+     */
+    public static function testIconvTruncateBug()
+    {
+        static $code = null;
+        if ($code === null) {
+            // better not use iconv, otherwise infinite loop!
+            $r = self::unsafeIconv('utf-8', 'ascii//IGNORE', "\xCE\xB1" . str_repeat('a', 9000));
+            if ($r === false) {
+                $code = self::ICONV_UNUSABLE;
+            } elseif (($c = strlen($r)) < 9000) {
+                $code = self::ICONV_TRUNCATES;
+            } elseif ($c > 9000) {
+                trigger_error(
+                    'Your copy of iconv is extremely buggy. Please notify HTML Purifier maintainers: ' .
+                    'include your iconv version as per phpversion()',
+                    E_USER_ERROR
+                );
+            } else {
+                $code = self::ICONV_OK;
+            }
+        }
+        return $code;
+    }
+    /**
+     * This expensive function tests whether or not a given character
+     * encoding supports ASCII. 7/8-bit encodings like Shift_JIS will
+     * fail this test, and require special processing. Variable width
+     * encodings shouldn't ever fail.
+     *
+     * @param string $encoding Encoding name to test, as per iconv format
+     * @param bool $bypass Whether or not to bypass the precompiled arrays.
+     * @return Array of UTF-8 characters to their corresponding ASCII,
+     *      which can be used to "undo" any overzealous iconv action.
+     */
+    public static function testEncodingSupportsASCII($encoding, $bypass = false)
+    {
+        // All calls to iconv here are unsafe, proof by case analysis:
+        // If ICONV_OK, no difference.
+        // If ICONV_TRUNCATE, all calls involve one character inputs,
+        // so bug is not triggered.
+        // If ICONV_UNUSABLE, this call is irrelevant
+        static $encodings = array();
+        if (!$bypass) {
+            if (isset($encodings[$encoding])) {
+                return $encodings[$encoding];
+            }
+            $lenc = strtolower($encoding);
+            switch ($lenc) {
+                case 'shift_jis':
+                    return array("\xC2\xA5" => '\\', "\xE2\x80\xBE" => '~');
+                case 'johab':
+                    return array("\xE2\x82\xA9" => '\\');
+            }
+            if (strpos($lenc, 'iso-8859-') === 0) {
+                return array();
+            }
+        }
+        $ret = array();
+        if (self::unsafeIconv('UTF-8', $encoding, 'a') === false) {
+            return false;
+        }
+        for ($i = 0x20; $i <= 0x7E; $i++) { // all printable ASCII chars
+            $c = chr($i); // UTF-8 char
+            $r = self::unsafeIconv('UTF-8', "$encoding//IGNORE", $c); // initial conversion
+            if ($r === '' ||
+                // This line is needed for iconv implementations that do not
+                // omit characters that do not exist in the target character set
+                ($r === $c && self::unsafeIconv($encoding, 'UTF-8//IGNORE', $r) !== $c)
+            ) {
+                // Reverse engineer: what's the UTF-8 equiv of this byte
+                // sequence? This assumes that there's no variable width
+                // encoding that doesn't support ASCII.
+                $ret[self::unsafeIconv($encoding, 'UTF-8//IGNORE', $c)] = $c;
+            }
+        }
+        $encodings[$encoding] = $ret;
+        return $ret;
+    }
+}
+// vim: et sw=4 sts=4
author	Nicolas Lœuillet <nicolas@loeuillet.org>	2014-02-21 15:57:10 +0100
committer	Nicolas Lœuillet <nicolas@loeuillet.org>	2014-02-21 15:57:10 +0100
commit	99679d06884120c57f43b44e55e03595f1f87bed (patch)
tree	a3f2a1aa1afdaeca1386d0c6e8a75344fd2241fb /inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php
parent	655214ab30ee84884dc408488b85586f36263fcb (diff)
parent	d3b47e94705e17b3ba3529cbb1dc6efe69c5d2b7 (diff)
download	wallabag-99679d06884120c57f43b44e55e03595f1f87bed.tar.gz wallabag-99679d06884120c57f43b44e55e03595f1f87bed.tar.zst wallabag-99679d06884120c57f43b44e55e03595f1f87bed.zip

diff --git a/inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php b/inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php new file mode 100644 index 00000000..3aa00ca5 --- /dev/null +++ b/inc/3rdparty/htmlpurifier/HTMLPurifier/Encoder.php
@@ -0,0 +1,611 @@
	1	<?php
	2
	3	/**
	4	* A UTF-8 specific character encoder that handles cleaning and transforming.
	5	* @note All functions in this class should be static.
	6	*/
	7	class HTMLPurifier_Encoder
	8	{
	9
	10	/**
	11	* Constructor throws fatal error if you attempt to instantiate class
	12	*/
	13	private function __construct()
	14	{
	15	trigger_error('Cannot instantiate encoder, call methods statically', E_USER_ERROR);
	16	}
	17
	18	/**
	19	* Error-handler that mutes errors, alternative to shut-up operator.
	20	*/
	21	public static function muteErrorHandler()
	22	{
	23	}
	24
	25	/**
	26	* iconv wrapper which mutes errors, but doesn't work around bugs.
	27	* @param string $in Input encoding
	28	* @param string $out Output encoding
	29	* @param string $text The text to convert
	30	* @return string
	31	*/
	32	public static function unsafeIconv($in, $out, $text)
	33	{
	34	set_error_handler(array('HTMLPurifier_Encoder', 'muteErrorHandler'));
	35	$r = iconv($in, $out, $text);
	36	restore_error_handler();
	37	return $r;
	38	}
	39
	40	/**
	41	* iconv wrapper which mutes errors and works around bugs.
	42	* @param string $in Input encoding
	43	* @param string $out Output encoding
	44	* @param string $text The text to convert
	45	* @param int $max_chunk_size
	46	* @return string
	47	*/
	48	public static function iconv($in, $out, $text, $max_chunk_size = 8000)
	49	{
	50	$code = self::testIconvTruncateBug();
	51	if ($code == self::ICONV_OK) {
	52	return self::unsafeIconv($in, $out, $text);
	53	} elseif ($code == self::ICONV_TRUNCATES) {
	54	// we can only work around this if the input character set
	55	// is utf-8
	56	if ($in == 'utf-8') {
	57	if ($max_chunk_size < 4) {
	58	trigger_error('max_chunk_size is too small', E_USER_WARNING);
	59	return false;
	60	}
	61	// split into 8000 byte chunks, but be careful to handle
	62	// multibyte boundaries properly
	63	if (($c = strlen($text)) <= $max_chunk_size) {
	64	return self::unsafeIconv($in, $out, $text);
	65	}
	66	$r = '';
	67	$i = 0;
	68	while (true) {
	69	if ($i + $max_chunk_size >= $c) {
	70	$r .= self::unsafeIconv($in, $out, substr($text, $i));
	71	break;
	72	}
	73	// wibble the boundary
	74	if (0x80 != (0xC0 & ord($text[$i + $max_chunk_size]))) {
	75	$chunk_size = $max_chunk_size;
	76	} elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 1]))) {
	77	$chunk_size = $max_chunk_size - 1;
	78	} elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 2]))) {
	79	$chunk_size = $max_chunk_size - 2;
	80	} elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 3]))) {
	81	$chunk_size = $max_chunk_size - 3;
	82	} else {
	83	return false; // rather confusing UTF-8...
	84	}
	85	$chunk = substr($text, $i, $chunk_size); // substr doesn't mind overlong lengths
	86	$r .= self::unsafeIconv($in, $out, $chunk);
	87	$i += $chunk_size;
	88	}
	89	return $r;
	90	} else {
	91	return false;
	92	}
	93	} else {
	94	return false;
	95	}
	96	}
	97
	98	/**
	99	* Cleans a UTF-8 string for well-formedness and SGML validity
	100	*
	101	* It will parse according to UTF-8 and return a valid UTF8 string, with
	102	* non-SGML codepoints excluded.
	103	*
	104	* @param string $str The string to clean
	105	* @param bool $force_php
	106	* @return string
	107	*
	108	* @note Just for reference, the non-SGML code points are 0 to 31 and
	109	* 127 to 159, inclusive. However, we allow code points 9, 10
	110	* and 13, which are the tab, line feed and carriage return
	111	* respectively. 128 and above the code points map to multibyte
	112	* UTF-8 representations.
	113	*
	114	* @note Fallback code adapted from utf8ToUnicode by Henri Sivonen and
	115	* hsivonen@iki.fi at <http://iki.fi/hsivonen/php-utf8/> under the
	116	* LGPL license. Notes on what changed are inside, but in general,
	117	* the original code transformed UTF-8 text into an array of integer
	118	* Unicode codepoints. Understandably, transforming that back to
	119	* a string would be somewhat expensive, so the function was modded to
	120	* directly operate on the string. However, this discourages code
	121	* reuse, and the logic enumerated here would be useful for any
	122	* function that needs to be able to understand UTF-8 characters.
	123	* As of right now, only smart lossless character encoding converters
	124	* would need that, and I'm probably not going to implement them.
	125	* Once again, PHP 6 should solve all our problems.
	126	*/
	127	public static function cleanUTF8($str, $force_php = false)
	128	{
	129	// UTF-8 validity is checked since PHP 4.3.5
	130	// This is an optimization: if the string is already valid UTF-8, no
	131	// need to do PHP stuff. 99% of the time, this will be the case.
	132	// The regexp matches the XML char production, as well as well as excluding
	133	// non-SGML codepoints U+007F to U+009F
	134	if (preg_match(
	135	'/^[\x{9}\x{A}\x{D}\x{20}-\x{7E}\x{A0}-\x{D7FF}\x{E000}-\x{FFFD}\x{10000}-\x{10FFFF}]*$/Du',
	136	$str
	137	)) {
	138	return $str;
	139	}
	140
	141	$mState = 0; // cached expected number of octets after the current octet
	142	// until the beginning of the next UTF8 character sequence
	143	$mUcs4 = 0; // cached Unicode character
	144	$mBytes = 1; // cached expected number of octets in the current sequence
	145
	146	// original code involved an $out that was an array of Unicode
	147	// codepoints. Instead of having to convert back into UTF-8, we've
	148	// decided to directly append valid UTF-8 characters onto a string
	149	// $out once they're done. $char accumulates raw bytes, while $mUcs4
	150	// turns into the Unicode code point, so there's some redundancy.
	151
	152	$out = '';
	153	$char = '';
	154
	155	$len = strlen($str);
	156	for ($i = 0; $i < $len; $i++) {
	157	$in = ord($str{$i});
	158	$char .= $str[$i]; // append byte to char
	159	if (0 == $mState) {
	160	// When mState is zero we expect either a US-ASCII character
	161	// or a multi-octet sequence.
	162	if (0 == (0x80 & ($in))) {
	163	// US-ASCII, pass straight through.
	164	if (($in <= 31 \|\| $in == 127) &&
	165	!($in == 9 \|\| $in == 13 \|\| $in == 10) // save \r\t\n
	166	) {
	167	// control characters, remove
	168	} else {
	169	$out .= $char;
	170	}
	171	// reset
	172	$char = '';
	173	$mBytes = 1;
	174	} elseif (0xC0 == (0xE0 & ($in))) {
	175	// First octet of 2 octet sequence
	176	$mUcs4 = ($in);
	177	$mUcs4 = ($mUcs4 & 0x1F) << 6;
	178	$mState = 1;
	179	$mBytes = 2;
	180	} elseif (0xE0 == (0xF0 & ($in))) {
	181	// First octet of 3 octet sequence
	182	$mUcs4 = ($in);
	183	$mUcs4 = ($mUcs4 & 0x0F) << 12;
	184	$mState = 2;
	185	$mBytes = 3;
	186	} elseif (0xF0 == (0xF8 & ($in))) {
	187	// First octet of 4 octet sequence
	188	$mUcs4 = ($in);
	189	$mUcs4 = ($mUcs4 & 0x07) << 18;
	190	$mState = 3;
	191	$mBytes = 4;
	192	} elseif (0xF8 == (0xFC & ($in))) {
	193	// First octet of 5 octet sequence.
	194	//
	195	// This is illegal because the encoded codepoint must be
	196	// either:
	197	// (a) not the shortest form or
	198	// (b) outside the Unicode range of 0-0x10FFFF.
	199	// Rather than trying to resynchronize, we will carry on
	200	// until the end of the sequence and let the later error
	201	// handling code catch it.
	202	$mUcs4 = ($in);
	203	$mUcs4 = ($mUcs4 & 0x03) << 24;
	204	$mState = 4;
	205	$mBytes = 5;
	206	} elseif (0xFC == (0xFE & ($in))) {
	207	// First octet of 6 octet sequence, see comments for 5
	208	// octet sequence.
	209	$mUcs4 = ($in);
	210	$mUcs4 = ($mUcs4 & 1) << 30;
	211	$mState = 5;
	212	$mBytes = 6;
	213	} else {
	214	// Current octet is neither in the US-ASCII range nor a
	215	// legal first octet of a multi-octet sequence.
	216	$mState = 0;
	217	$mUcs4 = 0;
	218	$mBytes = 1;
	219	$char = '';
	220	}
	221	} else {
	222	// When mState is non-zero, we expect a continuation of the
	223	// multi-octet sequence
	224	if (0x80 == (0xC0 & ($in))) {
	225	// Legal continuation.
	226	$shift = ($mState - 1) * 6;
	227	$tmp = $in;
	228	$tmp = ($tmp & 0x0000003F) << $shift;
	229	$mUcs4 \|= $tmp;
	230
	231	if (0 == --$mState) {
	232	// End of the multi-octet sequence. mUcs4 now contains
	233	// the final Unicode codepoint to be output
	234
	235	// Check for illegal sequences and codepoints.
	236
	237	// From Unicode 3.1, non-shortest form is illegal
	238	if (((2 == $mBytes) && ($mUcs4 < 0x0080)) \|\|
	239	((3 == $mBytes) && ($mUcs4 < 0x0800)) \|\|
	240	((4 == $mBytes) && ($mUcs4 < 0x10000)) \|\|
	241	(4 < $mBytes) \|\|
	242	// From Unicode 3.2, surrogate characters = illegal
	243	(($mUcs4 & 0xFFFFF800) == 0xD800) \|\|
	244	// Codepoints outside the Unicode range are illegal
	245	($mUcs4 > 0x10FFFF)
	246	) {
	247
	248	} elseif (0xFEFF != $mUcs4 && // omit BOM
	249	// check for valid Char unicode codepoints
	250	(
	251	0x9 == $mUcs4 \|\|
	252	0xA == $mUcs4 \|\|
	253	0xD == $mUcs4 \|\|
	254	(0x20 <= $mUcs4 && 0x7E >= $mUcs4) \|\|
	255	// 7F-9F is not strictly prohibited by XML,
	256	// but it is non-SGML, and thus we don't allow it
	257	(0xA0 <= $mUcs4 && 0xD7FF >= $mUcs4) \|\|
	258	(0x10000 <= $mUcs4 && 0x10FFFF >= $mUcs4)
	259	)
	260	) {
	261	$out .= $char;
	262	}
	263	// initialize UTF8 cache (reset)
	264	$mState = 0;
	265	$mUcs4 = 0;
	266	$mBytes = 1;
	267	$char = '';
	268	}
	269	} else {
	270	// ((0xC0 & (*in) != 0x80) && (mState != 0))
	271	// Incomplete multi-octet sequence.
	272	// used to result in complete fail, but we'll reset
	273	$mState = 0;
	274	$mUcs4 = 0;
	275	$mBytes = 1;
	276	$char ='';
	277	}
	278	}
	279	}
	280	return $out;
	281	}
	282
	283	/**
	284	* Translates a Unicode codepoint into its corresponding UTF-8 character.
	285	* @note Based on Feyd's function at
	286	* <http://forums.devnetwork.net/viewtopic.php?p=191404#191404>,
	287	* which is in public domain.
	288	* @note While we're going to do code point parsing anyway, a good
	289	* optimization would be to refuse to translate code points that
	290	* are non-SGML characters. However, this could lead to duplication.
	291	* @note This is very similar to the unichr function in
	292	* maintenance/generate-entity-file.php (although this is superior,
	293	* due to its sanity checks).
	294	*/
	295
	296	// +----------+----------+----------+----------+
	297	// \| 33222222 \| 22221111 \| 111111 \| \|
	298	// \| 10987654 \| 32109876 \| 54321098 \| 76543210 \| bit
	299	// +----------+----------+----------+----------+
	300	// \| \| \| \| 0xxxxxxx \| 1 byte 0x00000000..0x0000007F
	301	// \| \| \| 110yyyyy \| 10xxxxxx \| 2 byte 0x00000080..0x000007FF
	302	// \| \| 1110zzzz \| 10yyyyyy \| 10xxxxxx \| 3 byte 0x00000800..0x0000FFFF
	303	// \| 11110www \| 10wwzzzz \| 10yyyyyy \| 10xxxxxx \| 4 byte 0x00010000..0x0010FFFF
	304	// +----------+----------+----------+----------+
	305	// \| 00000000 \| 00011111 \| 11111111 \| 11111111 \| Theoretical upper limit of legal scalars: 2097151 (0x001FFFFF)
	306	// \| 00000000 \| 00010000 \| 11111111 \| 11111111 \| Defined upper limit of legal scalar codes
	307	// +----------+----------+----------+----------+
	308
	309	public static function unichr($code)
	310	{
	311	if ($code > 1114111 or $code < 0 or
	312	($code >= 55296 and $code <= 57343) ) {
	313	// bits are set outside the "valid" range as defined
	314	// by UNICODE 4.1.0
	315	return '';
	316	}
	317
	318	$x = $y = $z = $w = 0;
	319	if ($code < 128) {
	320	// regular ASCII character
	321	$x = $code;
	322	} else {
	323	// set up bits for UTF-8
	324	$x = ($code & 63) \| 128;
	325	if ($code < 2048) {
	326	$y = (($code & 2047) >> 6) \| 192;
	327	} else {
	328	$y = (($code & 4032) >> 6) \| 128;
	329	if ($code < 65536) {
	330	$z = (($code >> 12) & 15) \| 224;
	331	} else {
	332	$z = (($code >> 12) & 63) \| 128;
	333	$w = (($code >> 18) & 7) \| 240;
	334	}
	335	}
	336	}
	337	// set up the actual character
	338	$ret = '';
	339	if ($w) {
	340	$ret .= chr($w);
	341	}
	342	if ($z) {
	343	$ret .= chr($z);
	344	}
	345	if ($y) {
	346	$ret .= chr($y);
	347	}
	348	$ret .= chr($x);
	349
	350	return $ret;
	351	}
	352
	353	/**
	354	* @return bool
	355	*/
	356	public static function iconvAvailable()
	357	{
	358	static $iconv = null;
	359	if ($iconv === null) {
	360	$iconv = function_exists('iconv') && self::testIconvTruncateBug() != self::ICONV_UNUSABLE;
	361	}
	362	return $iconv;
	363	}
	364
	365	/**
	366	* Convert a string to UTF-8 based on configuration.
	367	* @param string $str The string to convert
	368	* @param HTMLPurifier_Config $config
	369	* @param HTMLPurifier_Context $context
	370	* @return string
	371	*/
	372	public static function convertToUTF8($str, $config, $context)
	373	{
	374	$encoding = $config->get('Core.Encoding');
	375	if ($encoding === 'utf-8') {
	376	return $str;
	377	}
	378	static $iconv = null;
	379	if ($iconv === null) {
	380	$iconv = self::iconvAvailable();
	381	}
	382	if ($iconv && !$config->get('Test.ForceNoIconv')) {
	383	// unaffected by bugs, since UTF-8 support all characters
	384	$str = self::unsafeIconv($encoding, 'utf-8//IGNORE', $str);
	385	if ($str === false) {
	386	// $encoding is not a valid encoding
	387	trigger_error('Invalid encoding ' . $encoding, E_USER_ERROR);
	388	return '';
	389	}
	390	// If the string is bjorked by Shift_JIS or a similar encoding
	391	// that doesn't support all of ASCII, convert the naughty
	392	// characters to their true byte-wise ASCII/UTF-8 equivalents.
	393	$str = strtr($str, self::testEncodingSupportsASCII($encoding));
	394	return $str;
	395	} elseif ($encoding === 'iso-8859-1') {
	396	$str = utf8_encode($str);
	397	return $str;
	398	}
	399	$bug = HTMLPurifier_Encoder::testIconvTruncateBug();
	400	if ($bug == self::ICONV_OK) {
	401	trigger_error('Encoding not supported, please install iconv', E_USER_ERROR);
	402	} else {
	403	trigger_error(
	404	'You have a buggy version of iconv, see https://bugs.php.net/bug.php?id=48147 ' .
	405	'and http://sourceware.org/bugzilla/show_bug.cgi?id=13541',
	406	E_USER_ERROR
	407	);
	408	}
	409	}
	410
	411	/**
	412	* Converts a string from UTF-8 based on configuration.
	413	* @param string $str The string to convert
	414	* @param HTMLPurifier_Config $config
	415	* @param HTMLPurifier_Context $context
	416	* @return string
	417	* @note Currently, this is a lossy conversion, with unexpressable
	418	* characters being omitted.
	419	*/
	420	public static function convertFromUTF8($str, $config, $context)
	421	{
	422	$encoding = $config->get('Core.Encoding');
	423	if ($escape = $config->get('Core.EscapeNonASCIICharacters')) {
	424	$str = self::convertToASCIIDumbLossless($str);
	425	}
	426	if ($encoding === 'utf-8') {
	427	return $str;
	428	}
	429	static $iconv = null;
	430	if ($iconv === null) {
	431	$iconv = self::iconvAvailable();
	432	}
	433	if ($iconv && !$config->get('Test.ForceNoIconv')) {
	434	// Undo our previous fix in convertToUTF8, otherwise iconv will barf
	435	$ascii_fix = self::testEncodingSupportsASCII($encoding);
	436	if (!$escape && !empty($ascii_fix)) {
	437	$clear_fix = array();
	438	foreach ($ascii_fix as $utf8 => $native) {
	439	$clear_fix[$utf8] = '';
	440	}
	441	$str = strtr($str, $clear_fix);
	442	}
	443	$str = strtr($str, array_flip($ascii_fix));
	444	// Normal stuff
	445	$str = self::iconv('utf-8', $encoding . '//IGNORE', $str);
	446	return $str;
	447	} elseif ($encoding === 'iso-8859-1') {
	448	$str = utf8_decode($str);
	449	return $str;
	450	}
	451	trigger_error('Encoding not supported', E_USER_ERROR);
	452	// You might be tempted to assume that the ASCII representation
	453	// might be OK, however, this is not universally true over all
	454	// encodings. So we take the conservative route here, rather
	455	// than forcibly turn on %Core.EscapeNonASCIICharacters
	456	}
	457
	458	/**
	459	* Lossless (character-wise) conversion of HTML to ASCII
	460	* @param string $str UTF-8 string to be converted to ASCII
	461	* @return string ASCII encoded string with non-ASCII character entity-ized
	462	* @warning Adapted from MediaWiki, claiming fair use: this is a common
	463	* algorithm. If you disagree with this license fudgery,
	464	* implement it yourself.
	465	* @note Uses decimal numeric entities since they are best supported.
	466	* @note This is a DUMB function: it has no concept of keeping
	467	* character entities that the projected character encoding
	468	* can allow. We could possibly implement a smart version
	469	* but that would require it to also know which Unicode
	470	* codepoints the charset supported (not an easy task).
	471	* @note Sort of with cleanUTF8() but it assumes that $str is
	472	* well-formed UTF-8
	473	*/
	474	public static function convertToASCIIDumbLossless($str)
	475	{
	476	$bytesleft = 0;
	477	$result = '';
	478	$working = 0;
	479	$len = strlen($str);
	480	for ($i = 0; $i < $len; $i++) {
	481	$bytevalue = ord($str[$i]);
	482	if ($bytevalue <= 0x7F) { //0xxx xxxx
	483	$result .= chr($bytevalue);
	484	$bytesleft = 0;
	485	} elseif ($bytevalue <= 0xBF) { //10xx xxxx
	486	$working = $working << 6;
	487	$working += ($bytevalue & 0x3F);
	488	$bytesleft--;
	489	if ($bytesleft <= 0) {
	490	$result .= "&#" . $working . ";";
	491	}
	492	} elseif ($bytevalue <= 0xDF) { //110x xxxx
	493	$working = $bytevalue & 0x1F;
	494	$bytesleft = 1;
	495	} elseif ($bytevalue <= 0xEF) { //1110 xxxx
	496	$working = $bytevalue & 0x0F;
	497	$bytesleft = 2;
	498	} else { //1111 0xxx
	499	$working = $bytevalue & 0x07;
	500	$bytesleft = 3;
	501	}
	502	}
	503	return $result;
	504	}
	505
	506	/** No bugs detected in iconv. */
	507	const ICONV_OK = 0;
	508
	509	/** Iconv truncates output if converting from UTF-8 to another
	510	* character set with //IGNORE, and a non-encodable character is found */
	511	const ICONV_TRUNCATES = 1;
	512
	513	/** Iconv does not support //IGNORE, making it unusable for
	514	* transcoding purposes */
	515	const ICONV_UNUSABLE = 2;
	516
	517	/**
	518	* glibc iconv has a known bug where it doesn't handle the magic
	519	* //IGNORE stanza correctly. In particular, rather than ignore
	520	* characters, it will return an EILSEQ after consuming some number
	521	* of characters, and expect you to restart iconv as if it were
	522	* an E2BIG. Old versions of PHP did not respect the errno, and
	523	* returned the fragment, so as a result you would see iconv
	524	* mysteriously truncating output. We can work around this by
	525	* manually chopping our input into segments of about 8000
	526	* characters, as long as PHP ignores the error code. If PHP starts
	527	* paying attention to the error code, iconv becomes unusable.
	528	*
	529	* @return int Error code indicating severity of bug.
	530	*/
	531	public static function testIconvTruncateBug()
	532	{
	533	static $code = null;
	534	if ($code === null) {
	535	// better not use iconv, otherwise infinite loop!
	536	$r = self::unsafeIconv('utf-8', 'ascii//IGNORE', "\xCE\xB1" . str_repeat('a', 9000));
	537	if ($r === false) {
	538	$code = self::ICONV_UNUSABLE;
	539	} elseif (($c = strlen($r)) < 9000) {
	540	$code = self::ICONV_TRUNCATES;
	541	} elseif ($c > 9000) {
	542	trigger_error(
	543	'Your copy of iconv is extremely buggy. Please notify HTML Purifier maintainers: ' .
	544	'include your iconv version as per phpversion()',
	545	E_USER_ERROR
	546	);
	547	} else {
	548	$code = self::ICONV_OK;
	549	}
	550	}
	551	return $code;
	552	}
	553
	554	/**
	555	* This expensive function tests whether or not a given character
	556	* encoding supports ASCII. 7/8-bit encodings like Shift_JIS will
	557	* fail this test, and require special processing. Variable width
	558	* encodings shouldn't ever fail.
	559	*
	560	* @param string $encoding Encoding name to test, as per iconv format
	561	* @param bool $bypass Whether or not to bypass the precompiled arrays.
	562	* @return Array of UTF-8 characters to their corresponding ASCII,
	563	* which can be used to "undo" any overzealous iconv action.
	564	*/
	565	public static function testEncodingSupportsASCII($encoding, $bypass = false)
	566	{
	567	// All calls to iconv here are unsafe, proof by case analysis:
	568	// If ICONV_OK, no difference.
	569	// If ICONV_TRUNCATE, all calls involve one character inputs,
	570	// so bug is not triggered.
	571	// If ICONV_UNUSABLE, this call is irrelevant
	572	static $encodings = array();
	573	if (!$bypass) {
	574	if (isset($encodings[$encoding])) {
	575	return $encodings[$encoding];
	576	}
	577	$lenc = strtolower($encoding);
	578	switch ($lenc) {
	579	case 'shift_jis':
	580	return array("\xC2\xA5" => '\\', "\xE2\x80\xBE" => '~');
	581	case 'johab':
	582	return array("\xE2\x82\xA9" => '\\');
	583	}
	584	if (strpos($lenc, 'iso-8859-') === 0) {
	585	return array();
	586	}
	587	}
	588	$ret = array();
	589	if (self::unsafeIconv('UTF-8', $encoding, 'a') === false) {
	590	return false;
	591	}
	592	for ($i = 0x20; $i <= 0x7E; $i++) { // all printable ASCII chars
	593	$c = chr($i); // UTF-8 char
	594	$r = self::unsafeIconv('UTF-8', "$encoding//IGNORE", $c); // initial conversion
	595	if ($r === '' \|\|
	596	// This line is needed for iconv implementations that do not
	597	// omit characters that do not exist in the target character set
	598	($r === $c && self::unsafeIconv($encoding, 'UTF-8//IGNORE', $r) !== $c)
	599	) {
	600	// Reverse engineer: what's the UTF-8 equiv of this byte
	601	// sequence? This assumes that there's no variable width
	602	// encoding that doesn't support ASCII.
	603	$ret[self::unsafeIconv($encoding, 'UTF-8//IGNORE', $c)] = $c;
	604	}
	605	}
	606	$encodings[$encoding] = $ret;
	607	return $ret;
	608	}
	609	}
	610
	611	// vim: et sw=4 sts=4