TYPO3 v15 dev-main snapshot ()

2026-08-10 22:31:09 +02:00
commit af8cc155b5
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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\LockAcquireException;
+use TYPO3\CMS\Core\Locking\Exception\LockCreateException;
+use TYPO3\CMS\Core\Security\BlockSerializationTrait;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
+
+/**
+ * Semaphore locking
+ */
+class SemaphoreLockStrategy implements LockingStrategyInterface
+{
+    use BlockSerializationTrait;
+
+    public const FILE_LOCK_FOLDER = 'lock/';
+    public const DEFAULT_PRIORITY = 25;
+
+    /**
+     * @var int Identifier used for this lock
+     */
+    protected $id;
+
+    /**
+     * @var resource|\SysvSemaphore|null Semaphore Resource used for this lock
+     */
+    protected $resource;
+
+    /**
+     * @var string
+     */
+    protected $filePath = '';
+
+    /**
+     * @var bool TRUE if lock is acquired
+     */
+    protected $isAcquired = false;
+
+    /**
+     * @param string $subject ID to identify this lock in the system
+     * @throws LockCreateException
+     */
+    public function __construct($subject)
+    {
+        /*
+         * Tests if the directory for semaphore 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 root-path/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 ' . $path, 1460976250);
+            }
+        }
+        if (!is_writable($path)) {
+            throw new LockCreateException('Cannot write to directory ' . $path, 1460976320);
+        }
+        $this->filePath = $path . 'sem_' . md5((string)$subject);
+        touch($this->filePath);
+        $this->id = ftok($this->filePath, 'A');
+        if ($this->id === -1) {
+            throw new LockCreateException('Cannot create key for semaphore using path ' . $this->filePath, 1396278734);
+        }
+    }
+
+    /**
+     * Destructor
+     */
+    public function __destruct()
+    {
+        $this->release();
+        // We do not call sem_remove() since this would remove the resource for other processes,
+        // we leave that to the system. This is not clean, but there's no other way to determine when
+        // a semaphore is no longer needed as a website is generally running endlessly
+        // and we have no way to detect if there is a process currently waiting on that lock
+        // or if the server is shutdown
+    }
+
+    /**
+     * Release the lock
+     *
+     * @return bool Returns TRUE on success or FALSE on failure
+     */
+    public function release()
+    {
+        if (!$this->isAcquired) {
+            return true;
+        }
+        $this->isAcquired = false;
+        return (bool)@sem_release($this->resource);
+    }
+
+    /**
+     * 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()
+    {
+        if (function_exists('sem_get')) {
+            return self::LOCK_CAPABILITY_EXCLUSIVE;
+        }
+        return 0;
+    }
+
+    /**
+     * Try to acquire a lock
+     *
+     * @param int $mode LOCK_CAPABILITY_EXCLUSIVE
+     * @return bool Returns TRUE if the lock was acquired successfully
+     * @throws LockAcquireException if a semaphore could not be retrieved
+     */
+    public function acquire($mode = self::LOCK_CAPABILITY_EXCLUSIVE)
+    {
+        if ($this->isAcquired) {
+            return true;
+        }
+
+        $resource = sem_get($this->id, 1);
+        if ($resource === false) {
+            throw new LockAcquireException('Unable to get semaphore with id ' . $this->id, 1313828196);
+        }
+        $this->resource = $resource;
+
+        $this->isAcquired = (bool)sem_acquire($this->resource);
+        return $this->isAcquired;
+    }
+
+    /**
+     * @return int Returns a priority for the method. 0 to 100, 100 is highest
+     */
+    public static function getPriority()
+    {
+        return $GLOBALS['TYPO3_CONF_VARS']['SYS']['locking']['strategies'][self::class]['priority']
+            ?? self::DEFAULT_PRIORITY;
+    }
+
+    /**
+     * Destroys the resource associated with the lock
+     */
+    public function destroy()
+    {
+        if ($this->resource) {
+            sem_remove($this->resource);
+            @unlink($this->filePath);
+        }
+    }
+}