functions/decode/utf_8.php

   1 <?php
   2
   3 /**
   4  * functions/decode/utf-8.php - utf-8 decoding functions
   5  *
   6  * This file contains utf-8 decoding function that is needed to read
   7  * utf-8 encoded mails in non-utf-8 locale.
   8  *
   9  * Every decoded character consists of n bytes. First byte is octal
  10  * 300-375, other bytes - always octals 200-277.
  11  *<pre>
  12  * Ranges (first byte):
  13  *                oct     dec    hex
  14  * Two byte   - 300-337 192-223 C0-DF
  15  * Three byte - 340-357 224-239 E0-EF
  16  * Four byte  - 360-367 240-247 F0-F7
  17  * Five byte  - 370-373 248-251 F8-FB
  18  * Six byte   - 374-375 252-253 FC-FD
  19  *
  20  * \a\b characters are decoded to html code calculated with formula:
  21  *  octdec(a-300)*64 + octdec(b-200)
  22  *
  23  * \a\b\c characters are decoded to html code calculated with formula:
  24  *  octdec(a-340)*64^2 + octdec(b-200)*64 + octdec(c-200)
  25  *
  26  * \a\b\c\d characters are decoded to html code calculated with formula:
  27  *  octdec(a-360)*64^3 + octdec(b-200)*64^2 +
  28  *  + octdec(c-200)*64 + octdec(d-200)
  29  *
  30  * \a\b\c\d\e characters are decoded to html code calculated with formula:
  31  *  octdec(a-370)*64^4 + octdec(b-200)*64^3 +
  32  *  + octdec(c-200)*64^2 + octdec(d-200)*64 + octdec(e-200)
  33  *
  34  * \a\b\c\d\e\f characters are decoded to html code calculated with formula:
  35  *  octdec(a-374)*64^5 + octdec(b-200)*64^4 + octdec(c-200)*64^3 +
  36  *  + octdec(d-200)*64^2 + octdec(e-200)*64 + octdec(f-200)
  37  *</pre>
  38  * @copyright 2003-2021 The SquirrelMail Project Team
  39  * @license http://opensource.org/licenses/gpl-license.php GNU Public License
  40  * @version $Id$
  41  * @package squirrelmail
  42  * @subpackage decode
  43  */
  44
  45 /**
  46  * Decode utf-8 strings
  47  * @param string $string Encoded string
  48  * @return string Decoded string
  49  */
  50 function charset_decode_utf_8 ($string) {
  51     global $squirrelmail_language;
  52
  53     // Japanese translation uses mbstring function to read utf-8
  54     if ($squirrelmail_language == 'ja_JP')
  55         return $string;
  56
  57     // don't do decoding when there are no 8bit symbols
  58     if (! sq_is8bit($string,'utf-8'))
  59         return $string;
  60
  61     // decode six byte unicode characters
  62     /* (i think currently there is no such symbol)
  63     $string = preg_replace_callback("/([\374-\375])([\200-\277])([\200-\277])([\200-\277])([\200-\277])([\200-\277])/",
  64     create_function ('$matches', 'return \'&#\'.((ord($matches[1])-252)*1073741824+(ord($matches[2])-200)*16777216+(ord($matches[3])-200)*262144+(ord($matches[4])-128)*4096+(ord($matches[5])-128)*64+(ord($matches[6])-128)).\';\';'),
  65     $string);
  66     */
  67
  68     // decode five byte unicode characters
  69     /* (i think currently there is no such symbol)
  70     $string = preg_replace_callback("/([\370-\373])([\200-\277])([\200-\277])([\200-\277])([\200-\277])/",
  71     create_function ('$matches', 'return \'&#\'.((ord($matches[1])-248)*16777216+(ord($matches[2])-200)*262144+(ord($matches[3])-128)*4096+(ord($matches[4])-128)*64+(ord($matches[5])-128)).\';\';'),
  72     $string);
  73     */
  74
  75     // decode four byte unicode characters
  76     $string = preg_replace_callback("/([\360-\367])([\200-\277])([\200-\277])([\200-\277])/",
  77                                     (check_php_version(5, 3, 0)
  78                                      ? function($matches) { return '&#'.((ord($matches[1])-240)*262144+(ord($matches[2])-128)*4096+(ord($matches[3])-128)*64+(ord($matches[4])-128)).';'; }
  79                                      : create_function ('$matches', 'return \'&#\'.((ord($matches[1])-240)*262144+(ord($matches[2])-128)*4096+(ord($matches[3])-128)*64+(ord($matches[4])-128)).\';\';')
  80                                     ),
  81                                     $string);
  82
  83     // decode three byte unicode characters
  84     $string = preg_replace_callback("/([\340-\357])([\200-\277])([\200-\277])/",
  85                                     (check_php_version(5, 3, 0)
  86                                      ? function($matches) { return '&#'.((ord($matches[1])-224)*4096+(ord($matches[2])-128)*64+(ord($matches[3])-128)).';'; }
  87                                      : create_function ('$matches', 'return \'&#\'.((ord($matches[1])-224)*4096+(ord($matches[2])-128)*64+(ord($matches[3])-128)).\';\';')
  88                                     ),
  89                                     $string);
  90
  91     // decode two byte unicode characters
  92     $string = preg_replace_callback("/([\300-\337])([\200-\277])/",
  93                                     (check_php_version(5, 3, 0)
  94                                      ? function($matches) { return '&#'.((ord($matches[1])-192)*64+(ord($matches[2])-128)).';'; }
  95                                      : create_function ('$matches', 'return \'&#\'.((ord($matches[1])-192)*64+(ord($matches[2])-128)).\';\';')
  96                                     ),
  97                                     $string);
  98
  99     // remove broken unicode
 100     $string = preg_replace("/[\200-\237]|\240|[\241-\377]/",'?',$string);
 101
 102     return $string;
 103 }