1<?php 2 3use dokuwiki\Utf8\Unicode; 4/** 5 * Class to safely store UTF-8 in a Filename 6 * 7 * Encodes a utf8 string using only the following characters 0-9a-z_.-% 8 * characters 0-9a-z in the original string are preserved, "plain". 9 * all other characters are represented in a substring that starts 10 * with '%' are "converted". 11 * The transition from converted substrings to plain characters is 12 * marked with a '.' 13 * 14 * @author Christopher Smith <chris@jalakai.co.uk> 15 * @date 2010-04-02 16 */ 17class SafeFN 18{ 19 20 // 'safe' characters are a superset of $plain, $pre_indicator and $post_indicator 21 private static $plain = '-./[_0123456789abcdefghijklmnopqrstuvwxyz'; // these characters aren't converted 22 private static $pre_indicator = '%'; 23 private static $post_indicator = ']'; 24 25 /** 26 * Convert an UTF-8 string to a safe ASCII String 27 * 28 * conversion process 29 * - if codepoint is a plain or post_indicator character, 30 * - if previous character was "converted", append post_indicator to output, clear "converted" flag 31 * - append ascii byte for character to output 32 * (continue to next character) 33 * 34 * - if codepoint is a pre_indicator character, 35 * - append ascii byte for character to output, set "converted" flag 36 * (continue to next character) 37 * 38 * (all remaining characters) 39 * - reduce codepoint value for non-printable ASCII characters (0x00 - 0x1f). Space becomes our zero. 40 * - convert reduced value to base36 (0-9a-z) 41 * - append $pre_indicator characater followed by base36 string to output, set converted flag 42 * (continue to next character) 43 * 44 * @param string $filename a utf8 string, should only include printable characters - not 0x00-0x1f 45 * @return string an encoded representation of $filename using only 'safe' ASCII characters 46 * 47 * @author Christopher Smith <chris@jalakai.co.uk> 48 */ 49 public static function encode($filename) { 50 return self::unicodeToSafe(Unicode::fromUtf8($filename)); 51 } 52 53 /** 54 * decoding process 55 * - split the string into substrings at any occurrence of pre or post indicator characters 56 * - check the first character of the substring 57 * - if its not a pre_indicator character 58 * - if previous character was converted, skip over post_indicator character 59 * - copy codepoint values of remaining characters to the output array 60 * - clear any converted flag 61 * (continue to next substring) 62 * 63 * _ else (its a pre_indicator character) 64 * - if string length is 1, copy the post_indicator character to the output array 65 * (continue to next substring) 66 * 67 * - else (string length > 1) 68 * - skip the pre-indicator character and convert remaining string from base36 to base10 69 * - increase codepoint value for non-printable ASCII characters (add 0x20) 70 * - append codepoint to output array 71 * (continue to next substring) 72 * 73 * @param string $filename a 'safe' encoded ASCII string, 74 * @return string decoded utf8 representation of $filename 75 * 76 * @author Christopher Smith <chris@jalakai.co.uk> 77 */ 78 public static function decode($filename) { 79 return Unicode::toUtf8(self::safeToUnicode(strtolower($filename))); 80 } 81 82 public static function validatePrintableUtf8($printable_utf8) { 83 return !preg_match('#[\x01-\x1f]#', $printable_utf8); 84 } 85 86 public static function validateSafe($safe) { 87 return !preg_match('#[^'.self::$plain.self::$post_indicator.self::$pre_indicator.']#', $safe); 88 } 89 90 /** 91 * convert an array of unicode codepoints into 'safe_filename' format 92 * 93 * @param array int $unicode an array of unicode codepoints 94 * @return string the unicode represented in 'safe_filename' format 95 * 96 * @author Christopher Smith <chris@jalakai.co.uk> 97 */ 98 private static function unicodeToSafe($unicode) { 99 100 $safe = ''; 101 $converted = false; 102 103 foreach ($unicode as $codepoint) { 104 if ($codepoint < 127 && (strpos(self::$plain.self::$post_indicator, chr($codepoint))!==false)) { 105 if ($converted) { 106 $safe .= self::$post_indicator; 107 $converted = false; 108 } 109 $safe .= chr($codepoint); 110 } elseif ($codepoint == ord(self::$pre_indicator)) { 111 $safe .= self::$pre_indicator; 112 $converted = true; 113 } else { 114 $safe .= self::$pre_indicator.base_convert((string)($codepoint-32), 10, 36); 115 $converted = true; 116 } 117 } 118 if($converted) $safe .= self::$post_indicator; 119 return $safe; 120 } 121 122 /** 123 * convert a 'safe_filename' string into an array of unicode codepoints 124 * 125 * @param string $safe a filename in 'safe_filename' format 126 * @return array int an array of unicode codepoints 127 * 128 * @author Christopher Smith <chris@jalakai.co.uk> 129 */ 130 private static function safeToUnicode($safe) { 131 132 $unicode = []; 133 $split = preg_split('#(?=['.self::$post_indicator.self::$pre_indicator.'])#', $safe, -1, PREG_SPLIT_NO_EMPTY); 134 135 $converted = false; 136 foreach ($split as $sub) { 137 $len = strlen($sub); 138 if ($sub[0] != self::$pre_indicator) { 139 // plain (unconverted) characters, optionally starting with a post_indicator 140 // set initial value to skip any post_indicator 141 for ($i=($converted?1:0); $i < $len; $i++) { 142 $unicode[] = ord($sub[$i]); 143 } 144 $converted = false; 145 } elseif ($len==1) { 146 // a pre_indicator character in the real data 147 $unicode[] = ord($sub); 148 $converted = true; 149 } else { 150 // a single codepoint in base36, adjusted for initial 32 non-printable chars 151 $unicode[] = 32 + (int)base_convert(substr($sub, 1), 36, 10); 152 $converted = true; 153 } 154 } 155 156 return $unicode; 157 } 158} 159