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<?php
/*
* This file is part of the TYPO3 CMS project.
*
* It is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License, either version 2
* of the License, or any later version.
*
* For the full copyright and license information, please read the
* LICENSE.txt file that was distributed with this source code.
*
* The TYPO3 project - inspiring people to share!
*/
namespace TYPO3\CMS\Core\Locking;
use TYPO3\CMS\Core\Core\Environment;
use TYPO3\CMS\Core\Locking\Exception\LockAcquireWouldBlockException;
use TYPO3\CMS\Core\Locking\Exception\LockCreateException;
use TYPO3\CMS\Core\Security\BlockSerializationTrait;
use TYPO3\CMS\Core\Utility\GeneralUtility;
/**
* Simple file locking
*/
class SimpleLockStrategy implements LockingStrategyInterface
{
use BlockSerializationTrait;
public const FILE_LOCK_FOLDER = 'lock/';
public const DEFAULT_PRIORITY = 50;
/**
* @var string File path used for this lock
*/
protected $filePath;
/**
* @var bool True if lock is acquired
*/
protected $isAcquired = false;
/**
* @var int Number of times a locked resource is tried to be acquired. Only used in manual locks method "simple".
*/
protected $loops = 150;
/**
* @var int Milliseconds after lock acquire is retried. $loops * $step results in the maximum delay of a lock. Only used in manual lock method "simple".
*/
protected $step = 200;
/**
* @param string $subject ID to identify this lock in the system
* @throws LockCreateException if the lock could not be created
*/
public function __construct($subject)
{
// Tests if the directory for simple locks is available.
// If not, the directory will be created. The lock path is usually
// below typo3temp/var, typo3temp/var itself should exist already (or getProjectPath . /var/ respectively)
if ($GLOBALS['TYPO3_CONF_VARS']['SYS']['locking']['strategies'][self::class]['lockFileDir'] ?? false) {
$path = Environment::getProjectPath() . '/'
. trim($GLOBALS['TYPO3_CONF_VARS']['SYS']['locking']['strategies'][self::class]['lockFileDir'], ' /')
. '/';
} else {
$path = Environment::getVarPath() . '/' . self::FILE_LOCK_FOLDER;
}
if (!is_dir($path)) {
// Not using mkdir_deep on purpose here, if typo3temp/var itself
// does not exist, this issue should be solved on a different
// level of the application.
if (!GeneralUtility::mkdir($path)) {
throw new LockCreateException('Cannot create directory ' . $path, 1460976286);
}
}
if (!is_writable($path)) {
throw new LockCreateException('Cannot write to directory ' . $path, 1460976340);
}
$this->filePath = $path . 'simple_' . md5((string)$subject);
}
/**
* @param int $loops Number of times a locked resource is tried to be acquired.
* @param int $step Milliseconds after lock acquire is retried. $loops * $step results in the maximum delay of a lock.
*/
public function init($loops = 0, $step = 0)
{
$this->loops = (int)$loops;
$this->step = (int)$step;
}
/**
* Destructor:
* Releases lock automatically when instance is destroyed and release resources
*/
public function __destruct()
{
$this->release();
}
/**
* Release the lock
*
* @return bool Returns TRUE on success or FALSE on failure
*/
public function release()
{
if (!$this->isAcquired) {
return true;
}
$success = true;
if (
GeneralUtility::isAllowedAbsPath($this->filePath)
&& str_starts_with($this->filePath, Environment::getVarPath() . '/' . self::FILE_LOCK_FOLDER)
) {
if (@unlink($this->filePath) === false) {
$success = false;
}
}
$this->isAcquired = false;
return $success;
}
/**
* Get status of this lock
*
* @return bool Returns TRUE if lock is acquired by this locker, FALSE otherwise
*/
public function isAcquired()
{
return $this->isAcquired;
}
/**
* @return int LOCK_CAPABILITY_* elements combined with bit-wise OR
*/
public static function getCapabilities()
{
return self::LOCK_CAPABILITY_EXCLUSIVE | self::LOCK_CAPABILITY_NOBLOCK;
}
/**
* Try to acquire a lock
*
* @param int $mode LOCK_CAPABILITY_EXCLUSIVE or self::LOCK_CAPABILITY_NOBLOCK
* @return bool Returns TRUE if the lock was acquired successfully
* @throws LockAcquireWouldBlockException
*/
public function acquire($mode = self::LOCK_CAPABILITY_EXCLUSIVE)
{
if ($this->isAcquired) {
return true;
}
if (file_exists($this->filePath)) {
$maxExecutionTime = (int)ini_get('max_execution_time');
$maxAge = time() - ($maxExecutionTime ?: 120);
if (@filectime($this->filePath) < $maxAge) {
// Remove stale lock file
@unlink($this->filePath);
}
}
$this->isAcquired = false;
$wouldBlock = false;
for ($i = 0; $i < $this->loops; $i++) {
$filePointer = @fopen($this->filePath, 'x');
if ($filePointer !== false) {
fclose($filePointer);
GeneralUtility::fixPermissions($this->filePath);
$this->isAcquired = true;
break;
}
if ($mode & self::LOCK_CAPABILITY_NOBLOCK) {
$wouldBlock = true;
break;
}
usleep($this->step * 1000);
}
if ($mode & self::LOCK_CAPABILITY_NOBLOCK && !$this->isAcquired && $wouldBlock) {
throw new LockAcquireWouldBlockException('Failed to acquire lock because the request would block.', 1460976403);
}
return $this->isAcquired;
}
/**
* @return int Returns a priority for the method. 0 to 100, 100 is highest
*/
public static function getPriority()
{
return $GLOBALS['TYPO3_CONF_VARS']['SYS']['locking']['strategies'][self::class]['priority']
?? self::DEFAULT_PRIORITY;
}
/**
* Destroys the resource associated with the lock
*/
public function destroy()
{
@unlink($this->filePath);
}
}