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<?php |
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/** |
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* Utility class for secure file erasure. |
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*/ |
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namespace CryptoManana\Utilities; |
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use CryptoManana\Core\Abstractions\Containers\AbstractRandomnessInjectable as RandomnessContainer; |
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use CryptoManana\Core\Interfaces\Containers\FileErasureInterface as SecureFileErasure; |
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use CryptoManana\Core\Traits\CommonValidations\FileNameValidationTrait as ValidateFileNames; |
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/** |
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* Class FileShredder - Utility class for file shredding. |
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* |
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* @package CryptoManana\Utilities |
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* |
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* @property \CryptoManana\Core\Abstractions\Randomness\AbstractGenerator $randomnessSource The randomness generator. |
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* |
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* @mixin ValidateFileNames |
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*/ |
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class FileShredder extends RandomnessContainer implements SecureFileErasure |
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{ |
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/** |
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* File name and path validations. |
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* |
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* {@internal Reusable implementation of the common file name validation. }} |
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*/ |
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use ValidateFileNames; |
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/** |
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* Internal method for calculating the file size in bytes. |
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* |
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* @param string $filename The filename and location. |
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* |
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* @return int The file size in bytes. |
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* @throws \Exception Validation errors. |
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*/ |
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protected function calculateFileSize($filename) |
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{ |
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$sizeInBytes = filesize($filename); |
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// @codeCoverageIgnoreStart |
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if ($sizeInBytes === false) { |
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throw new \RuntimeException('The operating system could not obtain the correct size of the file.'); |
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} |
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// @codeCoverageIgnoreEnd |
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return $sizeInBytes; |
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} |
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/** |
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* Internal method for writing of pseudo-random content to a file. |
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* |
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* @param string $filename The filename and location. |
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* @param int $pass The current iteration pass logic. |
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* @param int $flag The file handle lock flag. |
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* |
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* @return bool The write operation result. |
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* @throws \Exception Validation or filesystem errors. |
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*/ |
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protected function writeContentToFile($filename, $pass, $flag) |
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{ |
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$written = false; |
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if ($pass === 1) { |
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$written = file_put_contents($filename, "\x0", $flag); |
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} elseif ($pass === 2) { |
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$written = file_put_contents($filename, "\x1", $flag); |
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} elseif ($pass === 3) { |
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$written = file_put_contents($filename, $this->randomnessSource->getBytes(1), $flag); |
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} |
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return is_int($written); |
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} |
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/** |
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* Internal method for shredding the physical file based on the DOD 5220.22-M (3 passes) standard. |
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* |
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* @param string $filename The filename and location. |
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* |
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* @return bool The file shredding operation result. |
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* @throws \Exception Validation or filesystem errors. |
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*/ |
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protected function fileShredding($filename) |
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{ |
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$sizeInBytes = $this->calculateFileSize($filename); |
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for ($pass = 1; $pass <= 3; $pass++) { |
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for ($i = 0; $i < $sizeInBytes; $i++) { |
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$flag = ($i === 0) ? LOCK_EX : (FILE_APPEND | LOCK_EX); |
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$written = $this->writeContentToFile($filename, $pass, $flag); |
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// @codeCoverageIgnoreStart |
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if ($written === false) { |
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throw new \RuntimeException('Problem with writing to the current filesystem.'); |
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} |
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// @codeCoverageIgnoreEnd |
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} |
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// Sleep for 15 milliseconds for the disk verify the written data and sync buffers |
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usleep(15000); |
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} |
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$written = file_put_contents($filename, '', LOCK_EX); |
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return (unlink($filename) === true && $written !== false); |
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} |
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/** |
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* Data erasure and wiping of a file. |
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* |
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* @param string $filename The filename and location. |
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* |
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* @throws \Exception Validation errors. |
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* |
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* @note Files that are bigger than 2 GB may not be deletable or behave irrationally for x86 platforms. |
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*/ |
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public function eraseFile($filename) |
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{ |
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if (!is_string($filename)) { |
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throw new \InvalidArgumentException('The file path must be of type string.'); |
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} |
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$this->validateFileNamePath($filename); |
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// @codeCoverageIgnoreStart |
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if ($this->fileShredding($filename) === false) { |
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throw new \RuntimeException('Failed to delete the file from the filesystem.'); |
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} |
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// @codeCoverageIgnoreEnd |
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} |
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} |
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TonyKaravasilev /
CryptoManana
