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<?php |
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/** |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* You should have received a copy of the GNU General Public License |
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* along with this program (see LICENSE.txt in the base directory. If |
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* not, see:. |
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* |
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* @link <http://www.gnu.org/licenses/>. |
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* |
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* @author niel |
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* @copyright 2016 nZEDb |
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*/ |
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namespace App\Extensions\util; |
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/** |
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* Class PhpYenc. |
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* Optimized yEnc encoder/decoder implementation. |
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*/ |
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class PhpYenc |
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{ |
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/** |
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* Pre-computed decode translation table for non-escaped characters. |
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* Maps yEnc encoded byte to decoded byte: (byte - 42) % 256 |
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* @var array<string, string>|null |
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*/ |
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private static ?array $decodeTable = null; |
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/** |
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* Pre-computed decode translation table for escaped characters. |
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* Maps yEnc escaped byte to decoded byte: ((byte - 64) - 42) % 256 |
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* @var array<string, string>|null |
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*/ |
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private static ?array $escapeDecodeTable = null; |
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/** |
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* Initialize the decode translation tables (lazy initialization). |
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*/ |
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private static function initDecodeTables(): void |
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{ |
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if (self::$decodeTable !== null) { |
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return; |
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} |
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self::$decodeTable = []; |
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self::$escapeDecodeTable = []; |
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for ($i = 0; $i < 256; $i++) { |
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$char = \chr($i); |
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// Standard decode: (byte - 42) % 256 |
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self::$decodeTable[$char] = \chr(($i - 42 + 256) % 256); |
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// Escape decode: ((byte - 64) - 42) % 256 |
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self::$escapeDecodeTable[$char] = \chr((($i - 64 - 42) + 512) % 256); |
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} |
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} |
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public static function decode(&$text, bool $ignore = false): bool|string |
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{ |
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$crc = ''; |
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// Extract the yEnc string itself. |
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if (preg_match( |
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'/=ybegin.*size=(\d+).*\r\n(.*)(?:\r\n)?=yend.*size=(\d+)(.*)/ims', |
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$text, |
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$encoded |
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)) { |
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if (preg_match('/crc32=([0-9a-fA-F]+)/i', $encoded[4], $trailer)) { |
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$crc = trim($trailer[1]); |
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} |
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$headerSize = (int) $encoded[1]; |
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$trailerSize = (int) $encoded[3]; |
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$encoded = $encoded[2]; |
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} else { |
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return false; |
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} |
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// Make sure the header and trailer file sizes match up. |
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if ($headerSize !== $trailerSize) { |
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$message = 'Header and trailer file sizes do not match. This is a violation of the yEnc specification.'; |
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throw new \RuntimeException($message); |
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} |
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// Remove line breaks from the string (use str_replace with array for speed). |
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$encoded = str_replace(["\r\n", "\r", "\n"], '', $encoded); |
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// Fast decode using optimized method |
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$decoded = self::fastDecode($encoded); |
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// Make sure the decoded file size is the same as the size specified in the header. |
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$decodedLength = \strlen($decoded); |
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if ($decodedLength !== $headerSize) { |
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$message = 'Header file size ('.$headerSize.') and actual file size ('.$decodedLength.') do not match. The file is probably corrupt.'; |
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throw new \RuntimeException($message); |
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} |
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// Check the CRC value |
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if ($crc !== '' && (strcasecmp($crc, sprintf('%X', crc32($decoded))) !== 0)) { |
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$message = 'CRC32 checksums do not match. The file is probably corrupt.'; |
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throw new \RuntimeException($message); |
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} |
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return $decoded; |
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} |
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/** |
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* Fast yEnc decode using strtr and optimized escape handling. |
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* |
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* @param string $encoded The encoded string (without headers/line breaks) |
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* @return string The decoded string |
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*/ |
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private static function fastDecode(string $encoded): string |
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{ |
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self::initDecodeTables(); |
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/** @var array<string, string> $decodeTable */ |
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$decodeTable = self::$decodeTable; |
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/** @var array<string, string> $escapeDecodeTable */ |
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$escapeDecodeTable = self::$escapeDecodeTable; |
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// Check if there are any escape sequences |
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$escapePos = strpos($encoded, '='); |
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if ($escapePos === false) { |
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// No escape sequences - use fast strtr translation |
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return strtr($encoded, $decodeTable); |
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} |
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// Handle escape sequences |
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// First, process escape sequences by splitting on '=' |
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$parts = explode('=', $encoded); |
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$result = strtr($parts[0], $decodeTable); |
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$count = \count($parts); |
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for ($i = 1; $i < $count; $i++) { |
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$part = $parts[$i]; |
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if ($part === '') { |
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continue; |
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} |
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// First character after '=' is the escaped character |
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$result .= $escapeDecodeTable[$part[0]]; |
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// Rest of the part is normal encoded data |
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if (isset($part[1])) { |
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$result .= strtr(substr($part, 1), $decodeTable); |
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} |
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} |
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return $result; |
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} |
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/** |
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* Decode a string of text encoded with yEnc. Ignores all errors. |
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* |
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* @param string $text The encoded text to decode. |
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* @return string The decoded yEnc string, or the input string, if it's not yEnc. |
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*/ |
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public static function decodeIgnore(string &$text): string |
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{ |
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if (preg_match('/^(=yBegin.*=yEnd[^$]*)$/ims', $text, $input)) { |
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// Extract the encoded data, removing headers and line breaks |
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$input = preg_replace('/(^=yBegin.*\r\n)/im', '', $input[1], 1); |
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$input = preg_replace('/(^=yPart.*\r\n)/im', '', $input, 1); |
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$input = preg_replace('/(^=yEnd.*)/im', '', $input, 1); |
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$input = str_replace(["\r\n", "\r", "\n"], '', trim($input)); |
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// Use the fast decode method |
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$text = self::fastDecode($input); |
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} |
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return $text; |
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} |
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public static function enabled(): bool |
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{ |
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return true; |
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} |
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public static function encode($data, $filename, int $lineLength = 128, bool $crc32 = true): string |
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{ |
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// yEnc 1.3 draft doesn't allow line lengths of more than 254 bytes. |
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if ($lineLength > 254) { |
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$lineLength = 254; |
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} |
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if ($lineLength < 1) { |
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$message = $lineLength.' is not a valid line length.'; |
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throw new \RuntimeException($message); |
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} |
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$encoded = ''; |
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$stringLength = \strlen($data); |
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// Encode each character of the string one at a time. |
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foreach ($data as $i => $iValue) { |
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$value = ((\ord($iValue) + 42) % 256); |
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// Escape NULL, TAB, LF, CR, space, . and = characters. |
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$encoded .= match ($value) { |
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0, 10, 13, 61 => ('='.\chr(($value + 64) % 256)), |
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default => \chr($value), |
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}; |
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} |
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$encoded = |
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'=ybegin line='. |
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$lineLength. |
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' size='. |
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$stringLength. |
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' name='. |
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trim($filename). |
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"\r\n". |
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trim(chunk_split($encoded, $lineLength)). |
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"\r\n=yend size=". |
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$stringLength; |
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// Add a CRC32 checksum if desired. |
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if ($crc32 === true) { |
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$encoded .= ' crc32='.strtolower(sprintf('%X', crc32($data))); |
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} |
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return $encoded; |
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} |
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} |
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NNTmux /
newznab-tmux
This check looks for parameters that have been defined for a function or method, but which are not used in the method body.