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f45a286b AD |
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 | trigger_error('Cannot instantiate encoder, call methods statically', E_USER_ERROR); | |
15 | } | |
16 | ||
17 | /** | |
18 | * Error-handler that mutes errors, alternative to shut-up operator. | |
19 | */ | |
f4f0f80d | 20 | public static function muteErrorHandler() {} |
f45a286b | 21 | |
dd205fba MK |
22 | /** |
23 | * iconv wrapper which mutes errors, but doesn't work around bugs. | |
24 | */ | |
25 | public static function unsafeIconv($in, $out, $text) { | |
26 | set_error_handler(array('HTMLPurifier_Encoder', 'muteErrorHandler')); | |
27 | $r = iconv($in, $out, $text); | |
28 | restore_error_handler(); | |
29 | return $r; | |
30 | } | |
31 | ||
32 | /** | |
33 | * iconv wrapper which mutes errors and works around bugs. | |
34 | */ | |
35 | public static function iconv($in, $out, $text, $max_chunk_size = 8000) { | |
36 | $code = self::testIconvTruncateBug(); | |
37 | if ($code == self::ICONV_OK) { | |
38 | return self::unsafeIconv($in, $out, $text); | |
39 | } elseif ($code == self::ICONV_TRUNCATES) { | |
40 | // we can only work around this if the input character set | |
41 | // is utf-8 | |
42 | if ($in == 'utf-8') { | |
43 | if ($max_chunk_size < 4) { | |
44 | trigger_error('max_chunk_size is too small', E_USER_WARNING); | |
45 | return false; | |
46 | } | |
47 | // split into 8000 byte chunks, but be careful to handle | |
48 | // multibyte boundaries properly | |
49 | if (($c = strlen($text)) <= $max_chunk_size) { | |
50 | return self::unsafeIconv($in, $out, $text); | |
51 | } | |
52 | $r = ''; | |
53 | $i = 0; | |
54 | while (true) { | |
55 | if ($i + $max_chunk_size >= $c) { | |
56 | $r .= self::unsafeIconv($in, $out, substr($text, $i)); | |
57 | break; | |
58 | } | |
59 | // wibble the boundary | |
60 | if (0x80 != (0xC0 & ord($text[$i + $max_chunk_size]))) { | |
61 | $chunk_size = $max_chunk_size; | |
62 | } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 1]))) { | |
63 | $chunk_size = $max_chunk_size - 1; | |
64 | } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 2]))) { | |
65 | $chunk_size = $max_chunk_size - 2; | |
66 | } elseif (0x80 != (0xC0 & ord($text[$i + $max_chunk_size - 3]))) { | |
67 | $chunk_size = $max_chunk_size - 3; | |
68 | } else { | |
69 | return false; // rather confusing UTF-8... | |
70 | } | |
71 | $chunk = substr($text, $i, $chunk_size); // substr doesn't mind overlong lengths | |
72 | $r .= self::unsafeIconv($in, $out, $chunk); | |
73 | $i += $chunk_size; | |
74 | } | |
75 | return $r; | |
76 | } else { | |
77 | return false; | |
78 | } | |
79 | } else { | |
80 | return false; | |
81 | } | |
82 | } | |
83 | ||
f45a286b AD |
84 | /** |
85 | * Cleans a UTF-8 string for well-formedness and SGML validity | |
86 | * | |
87 | * It will parse according to UTF-8 and return a valid UTF8 string, with | |
88 | * non-SGML codepoints excluded. | |
89 | * | |
90 | * @note Just for reference, the non-SGML code points are 0 to 31 and | |
91 | * 127 to 159, inclusive. However, we allow code points 9, 10 | |
92 | * and 13, which are the tab, line feed and carriage return | |
93 | * respectively. 128 and above the code points map to multibyte | |
94 | * UTF-8 representations. | |
95 | * | |
96 | * @note Fallback code adapted from utf8ToUnicode by Henri Sivonen and | |
97 | * hsivonen@iki.fi at <http://iki.fi/hsivonen/php-utf8/> under the | |
98 | * LGPL license. Notes on what changed are inside, but in general, | |
99 | * the original code transformed UTF-8 text into an array of integer | |
100 | * Unicode codepoints. Understandably, transforming that back to | |
101 | * a string would be somewhat expensive, so the function was modded to | |
102 | * directly operate on the string. However, this discourages code | |
103 | * reuse, and the logic enumerated here would be useful for any | |
104 | * function that needs to be able to understand UTF-8 characters. | |
105 | * As of right now, only smart lossless character encoding converters | |
106 | * would need that, and I'm probably not going to implement them. | |
107 | * Once again, PHP 6 should solve all our problems. | |
108 | */ | |
109 | public static function cleanUTF8($str, $force_php = false) { | |
110 | ||
111 | // UTF-8 validity is checked since PHP 4.3.5 | |
112 | // This is an optimization: if the string is already valid UTF-8, no | |
113 | // need to do PHP stuff. 99% of the time, this will be the case. | |
114 | // The regexp matches the XML char production, as well as well as excluding | |
115 | // non-SGML codepoints U+007F to U+009F | |
116 | if (preg_match('/^[\x{9}\x{A}\x{D}\x{20}-\x{7E}\x{A0}-\x{D7FF}\x{E000}-\x{FFFD}\x{10000}-\x{10FFFF}]*$/Du', $str)) { | |
117 | return $str; | |
118 | } | |
119 | ||
120 | $mState = 0; // cached expected number of octets after the current octet | |
121 | // until the beginning of the next UTF8 character sequence | |
122 | $mUcs4 = 0; // cached Unicode character | |
123 | $mBytes = 1; // cached expected number of octets in the current sequence | |
124 | ||
125 | // original code involved an $out that was an array of Unicode | |
126 | // codepoints. Instead of having to convert back into UTF-8, we've | |
127 | // decided to directly append valid UTF-8 characters onto a string | |
128 | // $out once they're done. $char accumulates raw bytes, while $mUcs4 | |
129 | // turns into the Unicode code point, so there's some redundancy. | |
130 | ||
131 | $out = ''; | |
132 | $char = ''; | |
133 | ||
134 | $len = strlen($str); | |
135 | for($i = 0; $i < $len; $i++) { | |
136 | $in = ord($str{$i}); | |
137 | $char .= $str[$i]; // append byte to char | |
138 | if (0 == $mState) { | |
139 | // When mState is zero we expect either a US-ASCII character | |
140 | // or a multi-octet sequence. | |
141 | if (0 == (0x80 & ($in))) { | |
142 | // US-ASCII, pass straight through. | |
143 | if (($in <= 31 || $in == 127) && | |
144 | !($in == 9 || $in == 13 || $in == 10) // save \r\t\n | |
145 | ) { | |
146 | // control characters, remove | |
147 | } else { | |
148 | $out .= $char; | |
149 | } | |
150 | // reset | |
151 | $char = ''; | |
152 | $mBytes = 1; | |
153 | } elseif (0xC0 == (0xE0 & ($in))) { | |
154 | // First octet of 2 octet sequence | |
155 | $mUcs4 = ($in); | |
156 | $mUcs4 = ($mUcs4 & 0x1F) << 6; | |
157 | $mState = 1; | |
158 | $mBytes = 2; | |
159 | } elseif (0xE0 == (0xF0 & ($in))) { | |
160 | // First octet of 3 octet sequence | |
161 | $mUcs4 = ($in); | |
162 | $mUcs4 = ($mUcs4 & 0x0F) << 12; | |
163 | $mState = 2; | |
164 | $mBytes = 3; | |
165 | } elseif (0xF0 == (0xF8 & ($in))) { | |
166 | // First octet of 4 octet sequence | |
167 | $mUcs4 = ($in); | |
168 | $mUcs4 = ($mUcs4 & 0x07) << 18; | |
169 | $mState = 3; | |
170 | $mBytes = 4; | |
171 | } elseif (0xF8 == (0xFC & ($in))) { | |
172 | // First octet of 5 octet sequence. | |
173 | // | |
174 | // This is illegal because the encoded codepoint must be | |
175 | // either: | |
176 | // (a) not the shortest form or | |
177 | // (b) outside the Unicode range of 0-0x10FFFF. | |
178 | // Rather than trying to resynchronize, we will carry on | |
179 | // until the end of the sequence and let the later error | |
180 | // handling code catch it. | |
181 | $mUcs4 = ($in); | |
182 | $mUcs4 = ($mUcs4 & 0x03) << 24; | |
183 | $mState = 4; | |
184 | $mBytes = 5; | |
185 | } elseif (0xFC == (0xFE & ($in))) { | |
186 | // First octet of 6 octet sequence, see comments for 5 | |
187 | // octet sequence. | |
188 | $mUcs4 = ($in); | |
189 | $mUcs4 = ($mUcs4 & 1) << 30; | |
190 | $mState = 5; | |
191 | $mBytes = 6; | |
192 | } else { | |
193 | // Current octet is neither in the US-ASCII range nor a | |
194 | // legal first octet of a multi-octet sequence. | |
195 | $mState = 0; | |
196 | $mUcs4 = 0; | |
197 | $mBytes = 1; | |
198 | $char = ''; | |
199 | } | |
200 | } else { | |
201 | // When mState is non-zero, we expect a continuation of the | |
202 | // multi-octet sequence | |
203 | if (0x80 == (0xC0 & ($in))) { | |
204 | // Legal continuation. | |
205 | $shift = ($mState - 1) * 6; | |
206 | $tmp = $in; | |
207 | $tmp = ($tmp & 0x0000003F) << $shift; | |
208 | $mUcs4 |= $tmp; | |
209 | ||
210 | if (0 == --$mState) { | |
211 | // End of the multi-octet sequence. mUcs4 now contains | |
212 | // the final Unicode codepoint to be output | |
213 | ||
214 | // Check for illegal sequences and codepoints. | |
215 | ||
216 | // From Unicode 3.1, non-shortest form is illegal | |
217 | if (((2 == $mBytes) && ($mUcs4 < 0x0080)) || | |
218 | ((3 == $mBytes) && ($mUcs4 < 0x0800)) || | |
219 | ((4 == $mBytes) && ($mUcs4 < 0x10000)) || | |
220 | (4 < $mBytes) || | |
221 | // From Unicode 3.2, surrogate characters = illegal | |
222 | (($mUcs4 & 0xFFFFF800) == 0xD800) || | |
223 | // Codepoints outside the Unicode range are illegal | |
224 | ($mUcs4 > 0x10FFFF) | |
225 | ) { | |
226 | ||
227 | } elseif (0xFEFF != $mUcs4 && // omit BOM | |
228 | // check for valid Char unicode codepoints | |
229 | ( | |
230 | 0x9 == $mUcs4 || | |
231 | 0xA == $mUcs4 || | |
232 | 0xD == $mUcs4 || | |
233 | (0x20 <= $mUcs4 && 0x7E >= $mUcs4) || | |
234 | // 7F-9F is not strictly prohibited by XML, | |
235 | // but it is non-SGML, and thus we don't allow it | |
236 | (0xA0 <= $mUcs4 && 0xD7FF >= $mUcs4) || | |
237 | (0x10000 <= $mUcs4 && 0x10FFFF >= $mUcs4) | |
238 | ) | |
239 | ) { | |
240 | $out .= $char; | |
241 | } | |
242 | // initialize UTF8 cache (reset) | |
243 | $mState = 0; | |
244 | $mUcs4 = 0; | |
245 | $mBytes = 1; | |
246 | $char = ''; | |
247 | } | |
248 | } else { | |
249 | // ((0xC0 & (*in) != 0x80) && (mState != 0)) | |
250 | // Incomplete multi-octet sequence. | |
251 | // used to result in complete fail, but we'll reset | |
252 | $mState = 0; | |
253 | $mUcs4 = 0; | |
254 | $mBytes = 1; | |
255 | $char =''; | |
256 | } | |
257 | } | |
258 | } | |
259 | return $out; | |
260 | } | |
261 | ||
262 | /** | |
263 | * Translates a Unicode codepoint into its corresponding UTF-8 character. | |
264 | * @note Based on Feyd's function at | |
265 | * <http://forums.devnetwork.net/viewtopic.php?p=191404#191404>, | |
266 | * which is in public domain. | |
267 | * @note While we're going to do code point parsing anyway, a good | |
268 | * optimization would be to refuse to translate code points that | |
269 | * are non-SGML characters. However, this could lead to duplication. | |
270 | * @note This is very similar to the unichr function in | |
271 | * maintenance/generate-entity-file.php (although this is superior, | |
272 | * due to its sanity checks). | |
273 | */ | |
274 | ||
275 | // +----------+----------+----------+----------+ | |
276 | // | 33222222 | 22221111 | 111111 | | | |
277 | // | 10987654 | 32109876 | 54321098 | 76543210 | bit | |
278 | // +----------+----------+----------+----------+ | |
279 | // | | | | 0xxxxxxx | 1 byte 0x00000000..0x0000007F | |
280 | // | | | 110yyyyy | 10xxxxxx | 2 byte 0x00000080..0x000007FF | |
281 | // | | 1110zzzz | 10yyyyyy | 10xxxxxx | 3 byte 0x00000800..0x0000FFFF | |
282 | // | 11110www | 10wwzzzz | 10yyyyyy | 10xxxxxx | 4 byte 0x00010000..0x0010FFFF | |
283 | // +----------+----------+----------+----------+ | |
284 | // | 00000000 | 00011111 | 11111111 | 11111111 | Theoretical upper limit of legal scalars: 2097151 (0x001FFFFF) | |
285 | // | 00000000 | 00010000 | 11111111 | 11111111 | Defined upper limit of legal scalar codes | |
286 | // +----------+----------+----------+----------+ | |
287 | ||
288 | public static function unichr($code) { | |
289 | if($code > 1114111 or $code < 0 or | |
290 | ($code >= 55296 and $code <= 57343) ) { | |
291 | // bits are set outside the "valid" range as defined | |
292 | // by UNICODE 4.1.0 | |
293 | return ''; | |
294 | } | |
295 | ||
296 | $x = $y = $z = $w = 0; | |
297 | if ($code < 128) { | |
298 | // regular ASCII character | |
299 | $x = $code; | |
300 | } else { | |
301 | // set up bits for UTF-8 | |
302 | $x = ($code & 63) | 128; | |
303 | if ($code < 2048) { | |
304 | $y = (($code & 2047) >> 6) | 192; | |
305 | } else { | |
306 | $y = (($code & 4032) >> 6) | 128; | |
307 | if($code < 65536) { | |
308 | $z = (($code >> 12) & 15) | 224; | |
309 | } else { | |
310 | $z = (($code >> 12) & 63) | 128; | |
311 | $w = (($code >> 18) & 7) | 240; | |
312 | } | |
313 | } | |
314 | } | |
315 | // set up the actual character | |
316 | $ret = ''; | |
317 | if($w) $ret .= chr($w); | |
318 | if($z) $ret .= chr($z); | |
319 | if($y) $ret .= chr($y); | |
320 | $ret .= chr($x); | |
321 | ||
322 | return $ret; | |
323 | } | |
324 | ||
dd205fba MK |
325 | public static function iconvAvailable() { |
326 | static $iconv = null; | |
327 | if ($iconv === null) { | |
328 | $iconv = function_exists('iconv') && self::testIconvTruncateBug() != self::ICONV_UNUSABLE; | |
329 | } | |
330 | return $iconv; | |
331 | } | |
332 | ||
f45a286b AD |
333 | /** |
334 | * Converts a string to UTF-8 based on configuration. | |
335 | */ | |
336 | public static function convertToUTF8($str, $config, $context) { | |
f4f0f80d | 337 | $encoding = $config->get('Core.Encoding'); |
f45a286b AD |
338 | if ($encoding === 'utf-8') return $str; |
339 | static $iconv = null; | |
dd205fba | 340 | if ($iconv === null) $iconv = self::iconvAvailable(); |
f4f0f80d | 341 | if ($iconv && !$config->get('Test.ForceNoIconv')) { |
dd205fba MK |
342 | // unaffected by bugs, since UTF-8 support all characters |
343 | $str = self::unsafeIconv($encoding, 'utf-8//IGNORE', $str); | |
f45a286b AD |
344 | if ($str === false) { |
345 | // $encoding is not a valid encoding | |
f45a286b AD |
346 | trigger_error('Invalid encoding ' . $encoding, E_USER_ERROR); |
347 | return ''; | |
348 | } | |
349 | // If the string is bjorked by Shift_JIS or a similar encoding | |
350 | // that doesn't support all of ASCII, convert the naughty | |
351 | // characters to their true byte-wise ASCII/UTF-8 equivalents. | |
dd205fba | 352 | $str = strtr($str, self::testEncodingSupportsASCII($encoding)); |
f45a286b AD |
353 | return $str; |
354 | } elseif ($encoding === 'iso-8859-1') { | |
355 | $str = utf8_encode($str); | |
f45a286b AD |
356 | return $str; |
357 | } | |
358 | trigger_error('Encoding not supported, please install iconv', E_USER_ERROR); | |
359 | } | |
360 | ||
361 | /** | |
362 | * Converts a string from UTF-8 based on configuration. | |
363 | * @note Currently, this is a lossy conversion, with unexpressable | |
364 | * characters being omitted. | |
365 | */ | |
366 | public static function convertFromUTF8($str, $config, $context) { | |
f4f0f80d | 367 | $encoding = $config->get('Core.Encoding'); |
f4f0f80d | 368 | if ($escape = $config->get('Core.EscapeNonASCIICharacters')) { |
dd205fba | 369 | $str = self::convertToASCIIDumbLossless($str); |
f45a286b | 370 | } |
dd205fba MK |
371 | if ($encoding === 'utf-8') return $str; |
372 | static $iconv = null; | |
373 | if ($iconv === null) $iconv = self::iconvAvailable(); | |
f4f0f80d | 374 | if ($iconv && !$config->get('Test.ForceNoIconv')) { |
f45a286b | 375 | // Undo our previous fix in convertToUTF8, otherwise iconv will barf |
dd205fba | 376 | $ascii_fix = self::testEncodingSupportsASCII($encoding); |
f45a286b AD |
377 | if (!$escape && !empty($ascii_fix)) { |
378 | $clear_fix = array(); | |
379 | foreach ($ascii_fix as $utf8 => $native) $clear_fix[$utf8] = ''; | |
380 | $str = strtr($str, $clear_fix); | |
381 | } | |
382 | $str = strtr($str, array_flip($ascii_fix)); | |
383 | // Normal stuff | |
dd205fba | 384 | $str = self::iconv('utf-8', $encoding . '//IGNORE', $str); |
f45a286b AD |
385 | return $str; |
386 | } elseif ($encoding === 'iso-8859-1') { | |
387 | $str = utf8_decode($str); | |
f45a286b AD |
388 | return $str; |
389 | } | |
390 | trigger_error('Encoding not supported', E_USER_ERROR); | |
dd205fba MK |
391 | // You might be tempted to assume that the ASCII representation |
392 | // might be OK, however, this is *not* universally true over all | |
393 | // encodings. So we take the conservative route here, rather | |
394 | // than forcibly turn on %Core.EscapeNonASCIICharacters | |
f45a286b AD |
395 | } |
396 | ||
397 | /** | |
398 | * Lossless (character-wise) conversion of HTML to ASCII | |
399 | * @param $str UTF-8 string to be converted to ASCII | |
400 | * @returns ASCII encoded string with non-ASCII character entity-ized | |
401 | * @warning Adapted from MediaWiki, claiming fair use: this is a common | |
402 | * algorithm. If you disagree with this license fudgery, | |
403 | * implement it yourself. | |
404 | * @note Uses decimal numeric entities since they are best supported. | |
405 | * @note This is a DUMB function: it has no concept of keeping | |
406 | * character entities that the projected character encoding | |
407 | * can allow. We could possibly implement a smart version | |
408 | * but that would require it to also know which Unicode | |
409 | * codepoints the charset supported (not an easy task). | |
410 | * @note Sort of with cleanUTF8() but it assumes that $str is | |
411 | * well-formed UTF-8 | |
412 | */ | |
413 | public static function convertToASCIIDumbLossless($str) { | |
414 | $bytesleft = 0; | |
415 | $result = ''; | |
416 | $working = 0; | |
417 | $len = strlen($str); | |
418 | for( $i = 0; $i < $len; $i++ ) { | |
419 | $bytevalue = ord( $str[$i] ); | |
420 | if( $bytevalue <= 0x7F ) { //0xxx xxxx | |
421 | $result .= chr( $bytevalue ); | |
422 | $bytesleft = 0; | |
423 | } elseif( $bytevalue <= 0xBF ) { //10xx xxxx | |
424 | $working = $working << 6; | |
425 | $working += ($bytevalue & 0x3F); | |
426 | $bytesleft--; | |
427 | if( $bytesleft <= 0 ) { | |
428 | $result .= "&#" . $working . ";"; | |
429 | } | |
430 | } elseif( $bytevalue <= 0xDF ) { //110x xxxx | |
431 | $working = $bytevalue & 0x1F; | |
432 | $bytesleft = 1; | |
433 | } elseif( $bytevalue <= 0xEF ) { //1110 xxxx | |
434 | $working = $bytevalue & 0x0F; | |
435 | $bytesleft = 2; | |
436 | } else { //1111 0xxx | |
437 | $working = $bytevalue & 0x07; | |
438 | $bytesleft = 3; | |
439 | } | |
440 | } | |
441 | return $result; | |
442 | } | |
443 | ||
dd205fba MK |
444 | /** No bugs detected in iconv. */ |
445 | const ICONV_OK = 0; | |
446 | ||
447 | /** Iconv truncates output if converting from UTF-8 to another | |
448 | * character set with //IGNORE, and a non-encodable character is found */ | |
449 | const ICONV_TRUNCATES = 1; | |
450 | ||
451 | /** Iconv does not support //IGNORE, making it unusable for | |
452 | * transcoding purposes */ | |
453 | const ICONV_UNUSABLE = 2; | |
454 | ||
455 | /** | |
456 | * glibc iconv has a known bug where it doesn't handle the magic | |
457 | * //IGNORE stanza correctly. In particular, rather than ignore | |
458 | * characters, it will return an EILSEQ after consuming some number | |
459 | * of characters, and expect you to restart iconv as if it were | |
460 | * an E2BIG. Old versions of PHP did not respect the errno, and | |
461 | * returned the fragment, so as a result you would see iconv | |
462 | * mysteriously truncating output. We can work around this by | |
463 | * manually chopping our input into segments of about 8000 | |
464 | * characters, as long as PHP ignores the error code. If PHP starts | |
465 | * paying attention to the error code, iconv becomes unusable. | |
466 | * | |
467 | * @returns Error code indicating severity of bug. | |
468 | */ | |
469 | public static function testIconvTruncateBug() { | |
470 | static $code = null; | |
471 | if ($code === null) { | |
472 | // better not use iconv, otherwise infinite loop! | |
473 | $r = self::unsafeIconv('utf-8', 'ascii//IGNORE', "\xCE\xB1" . str_repeat('a', 9000)); | |
474 | if ($r === false) { | |
475 | $code = self::ICONV_UNUSABLE; | |
476 | } elseif (($c = strlen($r)) < 9000) { | |
477 | $code = self::ICONV_TRUNCATES; | |
478 | } elseif ($c > 9000) { | |
479 | trigger_error('Your copy of iconv is extremely buggy. Please notify HTML Purifier maintainers: include your iconv version as per phpversion()', E_USER_ERROR); | |
480 | } else { | |
481 | $code = self::ICONV_OK; | |
482 | } | |
483 | } | |
484 | return $code; | |
485 | } | |
486 | ||
f45a286b AD |
487 | /** |
488 | * This expensive function tests whether or not a given character | |
489 | * encoding supports ASCII. 7/8-bit encodings like Shift_JIS will | |
490 | * fail this test, and require special processing. Variable width | |
491 | * encodings shouldn't ever fail. | |
492 | * | |
493 | * @param string $encoding Encoding name to test, as per iconv format | |
494 | * @param bool $bypass Whether or not to bypass the precompiled arrays. | |
495 | * @return Array of UTF-8 characters to their corresponding ASCII, | |
496 | * which can be used to "undo" any overzealous iconv action. | |
497 | */ | |
498 | public static function testEncodingSupportsASCII($encoding, $bypass = false) { | |
dd205fba MK |
499 | // All calls to iconv here are unsafe, proof by case analysis: |
500 | // If ICONV_OK, no difference. | |
501 | // If ICONV_TRUNCATE, all calls involve one character inputs, | |
502 | // so bug is not triggered. | |
503 | // If ICONV_UNUSABLE, this call is irrelevant | |
f45a286b AD |
504 | static $encodings = array(); |
505 | if (!$bypass) { | |
506 | if (isset($encodings[$encoding])) return $encodings[$encoding]; | |
507 | $lenc = strtolower($encoding); | |
508 | switch ($lenc) { | |
509 | case 'shift_jis': | |
510 | return array("\xC2\xA5" => '\\', "\xE2\x80\xBE" => '~'); | |
511 | case 'johab': | |
512 | return array("\xE2\x82\xA9" => '\\'); | |
513 | } | |
514 | if (strpos($lenc, 'iso-8859-') === 0) return array(); | |
515 | } | |
516 | $ret = array(); | |
dd205fba | 517 | if (self::unsafeIconv('UTF-8', $encoding, 'a') === false) return false; |
f45a286b AD |
518 | for ($i = 0x20; $i <= 0x7E; $i++) { // all printable ASCII chars |
519 | $c = chr($i); // UTF-8 char | |
dd205fba | 520 | $r = self::unsafeIconv('UTF-8', "$encoding//IGNORE", $c); // initial conversion |
f45a286b AD |
521 | if ( |
522 | $r === '' || | |
523 | // This line is needed for iconv implementations that do not | |
524 | // omit characters that do not exist in the target character set | |
dd205fba | 525 | ($r === $c && self::unsafeIconv($encoding, 'UTF-8//IGNORE', $r) !== $c) |
f45a286b AD |
526 | ) { |
527 | // Reverse engineer: what's the UTF-8 equiv of this byte | |
528 | // sequence? This assumes that there's no variable width | |
529 | // encoding that doesn't support ASCII. | |
dd205fba | 530 | $ret[self::unsafeIconv($encoding, 'UTF-8//IGNORE', $c)] = $c; |
f45a286b AD |
531 | } |
532 | } | |
f45a286b AD |
533 | $encodings[$encoding] = $ret; |
534 | return $ret; | |
535 | } | |
536 | ||
537 | ||
538 | } | |
539 | ||
540 | // vim: et sw=4 sts=4 |