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<?php |
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/* |
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* This file is part of the ManageWP Worker plugin. |
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* |
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* (c) ManageWP LLC <contact@managewp.com> |
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* |
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* For the full copyright and license information, please view the LICENSE |
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* file that was distributed with this source code. |
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*/ |
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|
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class MWP_Stream_Base64EncodedStream extends MWP_Stream_Decorator |
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{ |
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|
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/** @var MWP_Stream_Interface */ |
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private $buffer; |
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|
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const BASE64_BLOCK_SIZE = 4; |
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const ORIGIN_BLOCK_SIZE = 3; |
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|
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public function __construct(MWP_Stream_Interface $stream) |
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{ |
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parent::__construct($stream); |
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$this->buffer = new MWP_Stream_Buffer(); |
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} |
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|
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public function eof() |
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{ |
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return $this->buffer->eof() && $this->getStream()->eof(); |
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} |
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|
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public function read($length) |
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{ |
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$readFromBuffer = $this->buffer->read($length); |
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if (strlen($readFromBuffer) === $length) { |
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return $readFromBuffer; |
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} |
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|
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$remaining = $length - strlen($readFromBuffer); |
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|
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// Calculate the approximate length required to read so that the base64 encoded stream does not have padding. |
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// base64 is calculated for blocks of 3 input characters resulting in 4 output characters. |
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// strlen(base64_encode($str)) ==> strlen($str) * 4 / 3 |
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// |
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// This leads to: |
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// |
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// strlen($str) ==> strlen(base64_encode($str)) * 3 / 4 |
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// |
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// Meaning, to read $length characters from the base64 encoded string, read 3/4 of $length from the original stream. |
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// $length is first rounded to the first larger number divisible by 4 since base64 encoded strings come in blocks of 4 characters. |
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$closestGroupLength = $remaining + (self::BASE64_BLOCK_SIZE - $remaining % self::BASE64_BLOCK_SIZE); |
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$read = $closestGroupLength * self::ORIGIN_BLOCK_SIZE / self::BASE64_BLOCK_SIZE; |
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$this->buffer->write(base64_encode($this->getStream()->read($read))); |
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|
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return $readFromBuffer.$this->buffer->read($remaining); |
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} |
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} |
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|
