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<?php
/**
* Copyright (c) 2013 ownCloud, Inc.
* This file is licensed under the Affero General Public License version 3 or
* later.
* See the COPYING-README file.
*/
namespace OC\Files\Storage\Wrapper;
use OC\Files\Filesystem;
use OC\Files\Lock;
/**
* Class LockingWrapper
* A Storage Wrapper used to lock files at the system level
* @package OC\Files\Storage\Wrapper
*
* Notes: Does the $locks array need to be global to all LockingWrapper instances, such as in the case of two paths
* that point to the same physical file? Otherwise accessing the file from a different path the second time would show
* the file as locked, even though this process is the one locking it.
*/
class LockingWrapper extends Wrapper {
/** @var \OCP\Files\Lock[] $locks Holds an array of lock instances indexed by path for this storage */
protected $locks = array();
/**
* Acquire a lock on a file
* @param string $path Path to file, relative to this storage
* @param integer $lockType A Lock class constant, Lock::READ/Lock::WRITE
* @param null|resource $existingHandle An existing file handle from an fopen()
* @return bool|\OCP\Files\Lock Lock instance on success, false on failure
*/
protected function getLock($path, $lockType, $existingHandle = null){
$path = Filesystem::normalizePath($this->storage->getLocalFile($path));
if(!isset($this->locks[$path])) {
$this->locks[$path] = new Lock($path);
}
$this->locks[$path]->addLock($lockType, $existingHandle);
return $this->locks[$path];
}
/**
* Release an existing lock
* @param string $path Path to file, relative to this storage
* @param integer $lockType The type of lock to release
* @param bool $releaseAll If true, release all outstanding locks
* @return bool true on success, false on failure
*/
protected function releaseLock($path, $lockType, $releaseAll = false){
$path = Filesystem::normalizePath($this->storage->getLocalFile($path));
if(isset($this->locks[$path])) {
if($releaseAll) {
return $this->locks[$path]->releaseAll();
}
else {
return $this->locks[$path]->release($lockType);
}
}
return true;
}
/**
* see http://php.net/manual/en/function.file_get_contents.php
* @param string $path
* @return string
* @throws \Exception
*/
public function file_get_contents($path) {
try {
$this->getLock($path, Lock::READ);
$result = $this->storage->file_get_contents($path);
}
catch(\Exception $originalException) {
// Need to release the lock before more operations happen in upstream exception handlers
$this->releaseLock($path, Lock::READ);
throw $originalException;
}
$this->releaseLock($path, Lock::READ);
return $result;
}
public function file_put_contents($path, $data) {
try {
$this->getLock($path, Lock::WRITE);
$result = $this->storage->file_put_contents($path, $data);
}
catch(\Exception $originalException) {
// Release lock, throw original exception
$this->releaseLock($path, Lock::WRITE);
throw $originalException;
}
$this->releaseLock($path, Lock::WRITE);
return $result;
}
public function copy($path1, $path2) {
try {
$this->getLock($path1, Lock::READ);
$this->getLock($path2, Lock::WRITE);
$result = $this->storage->copy($path1, $path2);
}
catch(\Exception $originalException) {
// Release locks, throw original exception
$this->releaseLock($path1, Lock::READ);
$this->releaseLock($path2, Lock::WRITE);
throw $originalException;
}
$this->releaseLock($path1, Lock::READ);
$this->releaseLock($path2, Lock::WRITE);
return $result;
}
public function rename($path1, $path2) {
try {
$this->getLock($path1, Lock::READ);
$this->getLock($path2, Lock::WRITE);
$result = $this->storage->rename($path1, $path2);
}
catch(\Exception $originalException) {
// Release locks, throw original exception
$this->releaseLock($path1, Lock::READ);
$this->releaseLock($path2, Lock::WRITE);
throw $originalException;
}
$this->releaseLock($path1, Lock::READ);
$this->releaseLock($path2, Lock::WRITE);
return $result;
}
public function fopen($path, $mode) {
$lockType = Lock::READ;
switch ($mode) {
case 'r+':
case 'rb+':
case 'w+':
case 'wb+':
case 'x+':
case 'xb+':
case 'a+':
case 'ab+':
case 'c+':
case 'w':
case 'wb':
case 'x':
case 'xb':
case 'a':
case 'ab':
case 'c':
$lockType = Lock::WRITE;
break;
}
// The handle for $this->fopen() is used outside of this class, so the handle/lock can't be closed
// Instead, it will be closed when the request goes out of scope
// Storage doesn't have an fclose()
if($result = $this->storage->fopen($path, $mode)) {
$this->getLock($path, $lockType, $result);
}
return $result;
}
public function unlink($path) {
try {
if (\OC\Files\Filesystem::is_file($path)) {
$this->getLock($path, Lock::WRITE);
}
$result = $this->storage->unlink($path);
}
catch(\Exception $originalException) {
// Need to release the lock before more operations happen in upstream exception handlers
$this->releaseLock($path, Lock::WRITE);
throw $originalException;
}
$this->releaseLock($path, Lock::WRITE);
return $result;
}
}
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