434 lines
12 KiB
PHP
434 lines
12 KiB
PHP
<?php
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/**
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* ownCloud - Encryption stream wrapper
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*
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* @copyright (C) 2015 ownCloud, Inc.
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*
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* @author Bjoern Schiessle <schiessle@owncloud.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
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* License as published by the Free Software Foundation; either
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* version 3 of the License, or any later version.
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*
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* This library 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
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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namespace OC\Files\Stream;
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use Icewind\Streams\Wrapper;
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use OC\Encryption\Exceptions\EncryptionHeaderKeyExistsException;
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class Encryption extends Wrapper {
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/** @var \OC\Encryption\Util */
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protected $util;
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/** @var \OC\Encryption\File */
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protected $file;
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/** @var \OCP\Encryption\IEncryptionModule */
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protected $encryptionModule;
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/** @var \OC\Files\Storage\Storage */
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protected $storage;
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/** @var \OC\Files\Storage\Wrapper\Encryption */
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protected $encryptionStorage;
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/** @var string */
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protected $internalPath;
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/** @var string */
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protected $cache;
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/** @var integer */
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protected $size;
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/** @var integer */
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protected $position;
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/** @var integer */
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protected $unencryptedSize;
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/** @var integer */
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protected $unencryptedBlockSize;
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/** @var array */
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protected $header;
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/** @var string */
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protected $fullPath;
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/**
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* header data returned by the encryption module, will be written to the file
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* in case of a write operation
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*
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* @var array
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*/
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protected $newHeader;
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/**
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* user who perform the read/write operation null for public access
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*
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* @var string
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*/
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protected $uid;
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/** @var bool */
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protected $readOnly;
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/** @var bool */
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protected $writeFlag;
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/** @var array */
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protected $expectedContextProperties;
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public function __construct() {
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$this->expectedContextProperties = array(
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'source',
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'storage',
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'internalPath',
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'fullPath',
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'encryptionModule',
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'header',
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'uid',
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'file',
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'util',
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'size',
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'unencryptedSize',
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'encryptionStorage'
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);
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}
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/**
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* Wraps a stream with the provided callbacks
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*
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* @param resource $source
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* @param string $internalPath relative to mount point
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* @param string $fullPath relative to data/
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* @param array $header
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* @param string $uid
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* @param \OCP\Encryption\IEncryptionModule $encryptionModule
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* @param \OC\Files\Storage\Storage $storage
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* @param \OC\Files\Storage\Wrapper\Encryption $encStorage
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* @param \OC\Encryption\Util $util
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* @param \OC\Encryption\File $file
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* @param string $mode
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* @param int $size
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* @param int $unencryptedSize
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* @return resource
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*
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* @throws \BadMethodCallException
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*/
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public static function wrap($source, $internalPath, $fullPath, array $header,
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$uid,
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\OCP\Encryption\IEncryptionModule $encryptionModule,
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\OC\Files\Storage\Storage $storage,
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\OC\Files\Storage\Wrapper\Encryption $encStorage,
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\OC\Encryption\Util $util,
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\OC\Encryption\File $file,
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$mode,
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$size,
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$unencryptedSize) {
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$context = stream_context_create(array(
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'ocencryption' => array(
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'source' => $source,
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'storage' => $storage,
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'internalPath' => $internalPath,
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'fullPath' => $fullPath,
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'encryptionModule' => $encryptionModule,
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'header' => $header,
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'uid' => $uid,
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'util' => $util,
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'file' => $file,
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'size' => $size,
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'unencryptedSize' => $unencryptedSize,
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'encryptionStorage' => $encStorage
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)
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));
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return self::wrapSource($source, $mode, $context, 'ocencryption', 'OC\Files\Stream\Encryption');
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}
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/**
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* add stream wrapper
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*
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* @param resource $source
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* @param string $mode
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* @param array $context
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* @param string $protocol
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* @param string $class
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* @return resource
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* @throws \BadMethodCallException
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*/
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protected static function wrapSource($source, $mode, $context, $protocol, $class) {
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try {
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stream_wrapper_register($protocol, $class);
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if (@rewinddir($source) === false) {
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$wrapped = fopen($protocol . '://', $mode, false, $context);
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} else {
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$wrapped = opendir($protocol . '://', $context);
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}
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} catch (\BadMethodCallException $e) {
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stream_wrapper_unregister($protocol);
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throw $e;
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}
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stream_wrapper_unregister($protocol);
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return $wrapped;
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}
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/**
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* Load the source from the stream context and return the context options
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*
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* @param string $name
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* @return array
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* @throws \BadMethodCallException
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*/
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protected function loadContext($name) {
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$context = parent::loadContext($name);
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foreach ($this->expectedContextProperties as $property) {
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if (array_key_exists($property, $context)) {
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$this->{$property} = $context[$property];
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} else {
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throw new \BadMethodCallException('Invalid context, "' . $property . '" options not set');
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}
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}
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return $context;
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}
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public function stream_open($path, $mode, $options, &$opened_path) {
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$this->loadContext('ocencryption');
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$this->position = 0;
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$this->cache = '';
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$this->writeFlag = false;
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$this->unencryptedBlockSize = $this->encryptionModule->getUnencryptedBlockSize();
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if (
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$mode === 'w'
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|| $mode === 'w+'
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|| $mode === 'wb'
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|| $mode === 'wb+'
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) {
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// We're writing a new file so start write counter with 0 bytes
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// TODO can we remove this completely?
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//$this->unencryptedSize = 0;
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//$this->size = 0;
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$this->readOnly = false;
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} else {
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$this->readOnly = true;
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}
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$sharePath = $this->fullPath;
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if (!$this->storage->file_exists($this->internalPath)) {
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$sharePath = dirname($path);
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}
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$accessList = $this->file->getAccessList($sharePath);
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$this->newHeader = $this->encryptionModule->begin($this->fullPath, $this->uid, $this->header, $accessList);
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return true;
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}
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public function stream_read($count) {
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$result = '';
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// skip the header if we read the file from the beginning
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if ($this->position === 0) {
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parent::stream_read($this->util->getHeaderSize());
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}
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// $count = min($count, $this->unencryptedSize - $this->position);
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while ($count > 0) {
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$remainingLength = $count;
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// update the cache of the current block
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$this->readCache();
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// determine the relative position in the current block
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$blockPosition = ($this->position % $this->unencryptedBlockSize);
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// if entire read inside current block then only position needs to be updated
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if ($remainingLength < ($this->unencryptedBlockSize - $blockPosition)) {
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$result .= substr($this->cache, $blockPosition, $remainingLength);
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$this->position += $remainingLength;
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$count = 0;
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// otherwise remainder of current block is fetched, the block is flushed and the position updated
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} else {
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$result .= substr($this->cache, $blockPosition);
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$this->flush();
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$this->position += ($this->unencryptedBlockSize - $blockPosition);
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$count -= ($this->unencryptedBlockSize - $blockPosition);
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}
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}
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return $result;
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}
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public function stream_write($data) {
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if ($this->position === 0) {
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$this->writeHeader();
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$this->size+=$this->util->getHeaderSize();
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}
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$length = 0;
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// loop over $data to fit it in 6126 sized unencrypted blocks
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while (strlen($data) > 0) {
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$remainingLength = strlen($data);
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// set the cache to the current 6126 block
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$this->readCache();
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// for seekable streams the pointer is moved back to the beginning of the encrypted block
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// flush will start writing there when the position moves to another block
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$positionInFile = floor($this->position / $this->unencryptedBlockSize) *
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$this->util->getBlockSize() + $this->util->getHeaderSize();
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$resultFseek = parent::stream_seek($positionInFile);
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// only allow writes on seekable streams, or at the end of the encrypted stream
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if (!($this->readOnly) && ($resultFseek || $positionInFile === $this->size)) {
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// switch the writeFlag so flush() will write the block
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$this->writeFlag = true;
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// determine the relative position in the current block
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$blockPosition = ($this->position % $this->unencryptedBlockSize);
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// check if $data fits in current block
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// if so, overwrite existing data (if any)
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// update position and liberate $data
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if ($remainingLength < ($this->unencryptedBlockSize - $blockPosition)) {
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$this->cache = substr($this->cache, 0, $blockPosition)
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. $data . substr($this->cache, $blockPosition + $remainingLength);
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$this->position += $remainingLength;
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$length += $remainingLength;
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$data = '';
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// if $data doesn't fit the current block, the fill the current block and reiterate
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// after the block is filled, it is flushed and $data is updatedxxx
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} else {
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$this->cache = substr($this->cache, 0, $blockPosition) .
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substr($data, 0, $this->unencryptedBlockSize - $blockPosition);
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$this->flush();
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$this->position += ($this->unencryptedBlockSize - $blockPosition);
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$length += ($this->unencryptedBlockSize - $blockPosition);
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$data = substr($data, $this->unencryptedBlockSize - $blockPosition);
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}
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} else {
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$data = '';
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}
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}
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$this->unencryptedSize = max($this->unencryptedSize, $this->position);
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return $length;
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}
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public function stream_tell() {
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return $this->position;
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}
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public function stream_seek($offset, $whence = SEEK_SET) {
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$return = false;
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switch ($whence) {
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case SEEK_SET:
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if ($offset < $this->unencryptedSize && $offset >= 0) {
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$newPosition = $offset;
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}
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break;
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case SEEK_CUR:
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if ($offset >= 0) {
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$newPosition = $offset + $this->position;
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}
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break;
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case SEEK_END:
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if ($this->unencryptedSize + $offset >= 0) {
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$newPosition = $this->unencryptedSize + $offset;
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}
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break;
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default:
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return $return;
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}
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$newFilePosition = floor($newPosition / $this->unencryptedBlockSize)
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* $this->util->getBlockSize() + $this->util->getHeaderSize();
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$oldFilePosition = parent::stream_tell();
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if (parent::stream_seek($newFilePosition)) {
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parent::stream_seek($oldFilePosition);
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$this->flush();
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parent::stream_seek($newFilePosition);
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$this->position = $newPosition;
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$return = true;
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}
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return $return;
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}
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public function stream_close() {
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$this->flush();
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$remainingData = $this->encryptionModule->end($this->fullPath);
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if ($this->readOnly === false) {
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if(!empty($remainingData)) {
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parent::stream_write($remainingData);
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}
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$this->encryptionStorage->updateUnencryptedSize($this->fullPath, $this->unencryptedSize);
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}
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return parent::stream_close();
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}
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/**
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* write block to file
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*/
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protected function flush() {
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// write to disk only when writeFlag was set to 1
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if ($this->writeFlag) {
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// Disable the file proxies so that encryption is not
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// automatically attempted when the file is written to disk -
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// we are handling that separately here and we don't want to
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// get into an infinite loop
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$encrypted = $this->encryptionModule->encrypt($this->cache);
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parent::stream_write($encrypted);
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$this->writeFlag = false;
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$this->size = max($this->size, parent::stream_tell());
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}
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// always empty the cache (otherwise readCache() will not fill it with the new block)
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$this->cache = '';
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}
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/**
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* read block to file
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*/
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protected function readCache() {
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// cache should always be empty string when this function is called
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// don't try to fill the cache when trying to write at the end of the unencrypted file when it coincides with new block
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if ($this->cache === '' && !($this->position === $this->unencryptedSize && ($this->position % $this->unencryptedBlockSize) === 0)) {
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// Get the data from the file handle
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$data = parent::stream_read($this->util->getBlockSize());
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$this->cache = $this->encryptionModule->decrypt($data);
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}
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}
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/**
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* write header at beginning of encrypted file
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*
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* @return integer
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* @throws EncryptionHeaderKeyExistsException if header key is already in use
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*/
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private function writeHeader() {
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$header = $this->util->createHeader($this->newHeader, $this->encryptionModule);
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return parent::stream_write($header);
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}
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}
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