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<?php
/**
* ownCloud
*
* @author Robin Appelman
* @copyright 2011 Robin Appelman icewind1991@gmail.com
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
* License as published by the Free Software Foundation; either
* version 3 of the License, or any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU AFFERO GENERAL PUBLIC LICENSE for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
*/
/**
* transparently encrypted filestream
*
* you can use it as wrapper around an existing stream by setting
* OC_CryptStream::$sourceStreams['foo']=array('path'=>$path, 'stream'=>$stream)
* and then fopen('crypt://streams/foo');
*/
class OC_CryptStream{
public static $sourceStreams=array();
private $source;
private $path;
private $meta=array();//header/meta for source stream
private $writeCache;
private $size;
private static $rootView;
public function stream_open($path, $mode, $options, &$opened_path) {
if ( ! self::$rootView) {
self::$rootView=new OC_FilesystemView('');
}
$path=str_replace('crypt://', '', $path);
if (dirname($path)=='streams' and isset(self::$sourceStreams[basename($path)])) {
$this->source=self::$sourceStreams[basename($path)]['stream'];
$this->path=self::$sourceStreams[basename($path)]['path'];
$this->size=self::$sourceStreams[basename($path)]['size'];
} else {
$this->path=$path;
if ($mode=='w' or $mode=='w+' or $mode=='wb' or $mode=='wb+') {
$this->size=0;
} else {
$this->size=self::$rootView->filesize($path, $mode);
}
OC_FileProxy::$enabled=false;//disable fileproxies so we can open the source file
$this->source=self::$rootView->fopen($path, $mode);
OC_FileProxy::$enabled=true;
if ( ! is_resource($this->source)) {
OCP\Util::writeLog('files_encryption', 'failed to open '.$path, OCP\Util::ERROR);
}
}
if (is_resource($this->source)) {
$this->meta=stream_get_meta_data($this->source);
}
return is_resource($this->source);
}
public function stream_seek($offset, $whence=SEEK_SET) {
$this->flush();
fseek($this->source, $offset, $whence);
}
public function stream_tell() {
return ftell($this->source);
}
public function stream_read($count) {
//$count will always be 8192 https://bugs.php.net/bug.php?id=21641
//This makes this function a lot simpler but will breake everything the moment it's fixed
$this->writeCache='';
if ($count!=8192) {
OCP\Util::writeLog('files_encryption',
'php bug 21641 no longer holds, decryption will not work',
OCP\Util::FATAL);
die();
}
$pos=ftell($this->source);
$data=fread($this->source, 8192);
if (strlen($data)) {
$result=OC_Crypt::decrypt($data);
} else {
$result='';
}
$length=$this->size-$pos;
if ($length<8192) {
$result=substr($result, 0, $length);
}
return $result;
}
public function stream_write($data) {
$length=strlen($data);
$currentPos=ftell($this->source);
if ($this->writeCache) {
$data=$this->writeCache.$data;
$this->writeCache='';
}
if ($currentPos%8192!=0) {
//make sure we always start on a block start
fseek($this->source, -($currentPos%8192), SEEK_CUR);
$encryptedBlock=fread($this->source, 8192);
fseek($this->source, -($currentPos%8192), SEEK_CUR);
$block=OC_Crypt::decrypt($encryptedBlock);
$data=substr($block, 0, $currentPos%8192).$data;
fseek($this->source, -($currentPos%8192), SEEK_CUR);
}
$currentPos=ftell($this->source);
while ($remainingLength=strlen($data)>0) {
if ($remainingLength<8192) {
$this->writeCache=$data;
$data='';
} else {
$encrypted=OC_Crypt::encrypt(substr($data, 0, 8192));
fwrite($this->source, $encrypted);
$data=substr($data, 8192);
}
}
$this->size=max($this->size, $currentPos+$length);
return $length;
}
public function stream_set_option($option, $arg1, $arg2) {
switch($option) {
case STREAM_OPTION_BLOCKING:
stream_set_blocking($this->source, $arg1);
break;
case STREAM_OPTION_READ_TIMEOUT:
stream_set_timeout($this->source, $arg1, $arg2);
break;
case STREAM_OPTION_WRITE_BUFFER:
stream_set_write_buffer($this->source, $arg1, $arg2);
}
}
public function stream_stat() {
return fstat($this->source);
}
public function stream_lock($mode) {
flock($this->source, $mode);
}
public function stream_flush() {
return fflush($this->source);
}
public function stream_eof() {
return feof($this->source);
}
private function flush() {
if ($this->writeCache) {
$encrypted=OC_Crypt::encrypt($this->writeCache);
fwrite($this->source, $encrypted);
$this->writeCache='';
}
}
public function stream_close() {
$this->flush();
if ($this->meta['mode']!='r' and $this->meta['mode']!='rb') {
OC_FileCache::put($this->path, array('encrypted'=>true, 'size'=>$this->size), '');
}
return fclose($this->source);
}
}
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