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lib/pkp/classes/cache/FileCache.php

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+<?php
+
+/**
+ * @defgroup cache Cache
+ * Implements various forms of caching, i.e. object caches, file caches, etc.
+ */
+
+/**
+ * @file classes/cache/FileCache.php
+ *
+ * Copyright (c) 2014-2021 Simon Fraser University
+ * Copyright (c) 2000-2021 John Willinsky
+ * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
+ *
+ * @class FileCache
+ *
+ * @ingroup cache
+ *
+ * @brief Provides caching based on machine-generated PHP code on the filesystem.
+ */
+
+namespace PKP\cache;
+
+use Exception;
+use PKP\config\Config;
+use PKP\file\FileManager;
+
+class FileCache extends GenericCache
+{
+    /**
+     * Connection to use for caching.
+     */
+    public $filename;
+
+    /**
+     * @var ?array The cached data
+     */
+    public $cache;
+
+    /**
+     * Instantiate a cache.
+     */
+    public function __construct($context, $cacheId, $fallback, $path)
+    {
+        parent::__construct($context, $cacheId, $fallback);
+
+        $this->filename = "{$path}/fc-{$context}-" . str_replace('/', '.', $cacheId) . '.php';
+
+        // If the file couldn't be opened or if a lock couldn't be acquired, quit
+        if (!($fp = @fopen($this->filename, 'r')) || !flock($fp, LOCK_SH)) {
+            $this->cache = null;
+            return;
+        }
+
+        // Reasoning: When the include below fails, it returns "false" and we have no way to determine if it's an error or a valid cache value
+        set_error_handler(static fn () => throw new Exception('Failed to include file'));
+        try {
+            $this->cache = include $this->filename;
+        } catch (Exception) {
+            $this->cache = null;
+        } finally {
+            restore_error_handler();
+            flock($fp, LOCK_UN);
+            fclose($fp);
+        }
+    }
+
+    /**
+     * Flush the cache
+     */
+    public function flush()
+    {
+        unset($this->cache);
+        $this->cache = null;
+        if (function_exists('opcache_invalidate')) {
+            opcache_invalidate($this->filename, true);
+        }
+        @unlink($this->filename);
+    }
+
+    /**
+     * Get an object from the cache.
+     *
+     * @param string $id
+     */
+    public function getCache($id)
+    {
+        if (!isset($this->cache)) {
+            return $this->cacheMiss;
+        }
+        return ($this->cache[$id] ?? null);
+    }
+
+    /**
+     * Set an object in the cache. This function should be overridden
+     * by subclasses.
+     *
+     * @param string $id
+     */
+    public function setCache($id, $value)
+    {
+        // Flush the cache; it will be regenerated on demand.
+        $this->flush();
+    }
+
+    /**
+     * Set the entire contents of the cache.
+     */
+    public function setEntireCache($contents)
+    {
+        if (@file_put_contents(
+            $this->filename,
+            '<?php return ' . var_export($contents, true) . ';',
+            LOCK_EX
+        ) !== false) {
+            $umask = Config::getVar('files', 'umask');
+            if ($umask) {
+                @chmod($this->filename, FileManager::FILE_MODE_MASK & ~$umask);
+            }
+        }
+        $this->cache = $contents;
+    }
+
+    /**
+     * Get the time at which the data was cached.
+     * If the file does not exist or an error occurs, null is returned.
+     *
+     * @return int|null
+     */
+    public function getCacheTime()
+    {
+        $result = @filemtime($this->filename);
+        if ($result === false) {
+            return null;
+        }
+        return ((int) $result);
+    }
+
+    /**
+     * Get the entire contents of the cache in an associative array.
+     */
+    public function &getContents()
+    {
+        if (!isset($this->cache)) {
+            // Trigger a cache miss to load the cache.
+            $this->get(null);
+        }
+        return $this->cache;
+    }
+}