SimpleLockStrategy.php

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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;
 
class ‪SimpleLockStrategy implements ‪LockingStrategyInterface
{
    use ‪BlockSerializationTrait;
 
    const ‪FILE_LOCK_FOLDER = 'lock/';
    const ‪DEFAULT_PRIORITY = 50;
 
    protected ‪$filePath;
 
    protected ‪$isAcquired = false;
 
    protected ‪$loops = 150;
 
    protected ‪$step = 200;
 
    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);
    }
 
    public function ‪init(‪$loops = 0, ‪$step = 0)
    {
        $this->loops = (int)‪$loops;
        $this->step = (int)‪$step;
    }
 
    public function ‪__destruct()
    {
        $this->‪release();
    }
 
    public function ‪release()
    {
        if (!$this->‪isAcquired) {
            return true;
        }
 
        $success = true;
        if (
            GeneralUtility::isAllowedAbsPath($this->filePath)
            && GeneralUtility::isFirstPartOfStr($this->filePath, ‪Environment::getVarPath() . '/' . self::FILE_LOCK_FOLDER)
        ) {
            if (@unlink($this->filePath) === false) {
                $success = false;
            }
        }
 
        $this->‪isAcquired = false;
        return $success;
    }
 
    public function ‪isAcquired()
    {
        return ‪$this->isAcquired;
    }
 
    public static function ‪getCapabilities()
    {
        return self::LOCK_CAPABILITY_EXCLUSIVE | ‪self::LOCK_CAPABILITY_NOBLOCK;
    }
 
    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;
    }
 
    public static function ‪getPriority()
    {
        return ‪$GLOBALS['TYPO3_CONF_VARS']['SYS']['locking']['strategies'][self::class]['priority']
            ?? ‪self::DEFAULT_PRIORITY;
    }
 
    public function ‪destroy()
    {
        @unlink($this->filePath);
    }
}