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                <?php  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * @author Ilja Neumann <[email protected]>  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * @copyright Copyright (c) 2018, ownCloud GmbH  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * @license AGPL-3.0  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * This code is free software: you can redistribute it and/or modify  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * it under the terms of the GNU Affero General Public License, version 3,  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * as published by the Free Software Foundation.  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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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 Affero General Public License for more details.  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * You should have received a copy of the GNU Affero General Public License, version 3,  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * along with this program.  If not, see <http://www.gnu.org/licenses/>  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                namespace OC\Files\Storage\Wrapper;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                use function GuzzleHttp\Psr7\stream_for;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                use GuzzleHttp\Psr7\StreamWrapper;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                use GuzzleHttp\Stream\GuzzleStreamWrapper;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                use Psr\Http\Message\StreamInterface;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                /**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * Class Checksum  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * Computes checksums (default: SHA1, MD5, ADLER32) on all files under the /files path.  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * The resulting checksum can be retrieved by call getMetadata($path)  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * If a file is read and has no checksum oc_filecache gets updated accordingly.  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 * @package OC\Files\Storage\Wrapper  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                class Checksum extends Wrapper { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	/** Format of checksum field in filecache */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	const CHECKSUMS_DB_FORMAT = 'SHA1:%s MD5:%s ADLER32:%s';  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	const NOT_REQUIRED = 0;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	/** Calculate checksum on write (to be stored in oc_filecache) */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	const PATH_NEW_OR_UPDATED = 1;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	/** File needs to be checksummed on first read because it is already in cache but has no checksum */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	const PATH_IN_CACHE_WITHOUT_CHECKSUM = 2;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	/** @var array */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	private $checksums;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * @param $path  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * @return string Format like "SHA1:abc MD5:def ADLER32:ghi"  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	private function getChecksumsInDbFormat($path) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if (empty($this->checksums[$path])) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			return '';  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if (!isset($this->checksums[$path]->md5)) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			throw new \BadMethodCallException('Reading from stream not yet finished. Close the stream before calling this method.'); | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return \sprintf(  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			self::CHECKSUMS_DB_FORMAT,  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			$this->checksums[$path]->sha1,  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			$this->checksums[$path]->md5,  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			$this->checksums[$path]->adler32  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * check if the file metadata should not be fetched  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * NOTE: files with a '.part' extension are ignored as well!  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 *       prevents unfinished put requests to fetch metadata which does not exists  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 *  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * @param string $file  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * @return boolean  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	public static function isPartialFile($file) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if (\pathinfo($file, PATHINFO_EXTENSION) === 'part') { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			return true;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return false;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	public function file_get_contents($path) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$stream = $this->readFile($path);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$data = $stream->getContents();  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$stream->close();  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return $data;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	public function file_put_contents($path, $data) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return $this->writeFile($path, stream_for($data));  | 
            
                            
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                	}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	public function writeFile(string $path, StreamInterface $stream) : int { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$this->checksums[$path] = new \stdClass();  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if (!\in_array('oc.checksum', \stream_get_filters(), true)) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			\stream_filter_register('oc.checksum', ChecksumFilter::class); | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$resource = StreamWrapper::getResource($stream);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		\stream_filter_append($resource, 'oc.checksum', STREAM_FILTER_READ, $this->checksums[$path]);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$checksumStream = stream_for($resource);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$return = $this->getWrapperStorage()->writeFile($path, $checksumStream);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$checksumStream->close();  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return $return;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	public function readFile(string $path, array $options = []): StreamInterface { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$this->checksums[$path] = new \stdClass();  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		if (!\in_array('oc.checksum', \stream_get_filters(), true)) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                			\stream_filter_register('oc.checksum', ChecksumFilter::class); | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$stream = $this->getWrapperStorage()->readFile($path, $options);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		$resource = StreamWrapper::getResource($stream);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		\stream_filter_append($resource, 'oc.checksum', STREAM_FILTER_READ, $this->checksums[$path]);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                		return stream_for($resource);  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	/**  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * @param string $path  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 * @return array  | 
            
            
                                                                                                            
                            
            
                                    
            
            
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                	 */  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
                | 
                    131
                 | 
                                    
                                                     | 
                
                 | 
                	public function getMetaData($path) { | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    132
                 | 
                                    
                                                     | 
                
                 | 
                		// Check if it is partial file. Partial file metadata are only checksums  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    133
                 | 
                                    
                                                     | 
                
                 | 
                		$parentMetaData = [];  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    134
                 | 
                                    
                                                     | 
                
                 | 
                		if (!self::isPartialFile($path)) { | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    135
                 | 
                                    
                                                     | 
                
                 | 
                			$parentMetaData = $this->getWrapperStorage()->getMetaData($path);  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    136
                 | 
                                    
                                                     | 
                
                 | 
                			// can be null if entry does not exist  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    137
                 | 
                                    
                                                     | 
                
                 | 
                			if ($parentMetaData === null) { | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    138
                 | 
                                    
                                                     | 
                
                 | 
                				return null;  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    139
                 | 
                                    
                                                     | 
                
                 | 
                			}  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    140
                 | 
                                    
                                                     | 
                
                 | 
                		}  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    141
                 | 
                                    
                                                     | 
                
                 | 
                		$parentMetaData['checksum'] = $this->getChecksumsInDbFormat($path);  | 
            
            
                                                                        
                            
            
                                    
            
            
                | 
                    142
                 | 
                                    
                                                     | 
                
                 | 
                 | 
            
            
                                                                                                            
                            
            
                                    
            
            
                | 
                    143
                 | 
                                    
                                                     | 
                
                 | 
                		if (!isset($parentMetaData['mimetype'])) { | 
            
            
                                                                                                            
                            
            
                                    
            
            
                | 
                    144
                 | 
                                    
                                                     | 
                
                 | 
                			$parentMetaData['mimetype'] = 'application/octet-stream';  | 
            
            
                                                                                                            
                            
            
                                    
            
            
                | 
                    145
                 | 
                                    
                                                     | 
                
                 | 
                		}  | 
            
            
                                                                                                            
                            
            
                                    
            
            
                | 
                    146
                 | 
                                    
                                                     | 
                
                 | 
                 | 
            
            
                                                                                                            
                            
            
                                    
            
            
                | 
                    147
                 | 
                                    
                                                     | 
                
                 | 
                		return $parentMetaData;  | 
            
            
                                                                                                            
                            
            
                                    
            
            
                | 
                    148
                 | 
                                    
                                                     | 
                
                 | 
                	}  | 
            
            
                                                                                                            
                                                                
            
                                    
            
            
                | 
                    149
                 | 
                                    
                                                     | 
                
                 | 
                }  | 
            
            
                                                        
            
                                    
            
            
                | 
                    150
                 | 
                                    
                                                     | 
                
                 | 
                 | 
            
            
                        
If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design.
Let’s take a look at an example:
Our function
my_functionexpects aPostobject, and outputs the author of the post. The base classPostreturns a simple string and outputting a simple string will work just fine. However, the child classBlogPostwhich is a sub-type ofPostinstead decided to return anobject, and is therefore violating the SOLID principles. If aBlogPostwere passed tomy_function, PHP would not complain, but ultimately fail when executing thestrtouppercall in its body.