name : Store.php
<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * This code is partially based on the Rack-Cache library by Ryan Tomayko,
 * which is released under the MIT license.
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\HttpKernel\HttpCache;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

/**
 * Store implements all the logic for storing cache metadata (Request and Response headers).
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class Store implements StoreInterface
{
    protected $root;
    /** @var \SplObjectStorage<Request, string> */
    private \SplObjectStorage $keyCache;
    /** @var array<string, resource> */
    private array $locks = [];
    private array $options;

    /**
     * Constructor.
     *
     * The available options are:
     *
     *   * private_headers  Set of response headers that should not be stored
     *                      when a response is cached. (default: Set-Cookie)
     *
     * @throws \RuntimeException
     */
    public function __construct(string $root, array $options = [])
    {
        $this->root = $root;
        if (!is_dir($this->root) && !@mkdir($this->root, 0777, true) && !is_dir($this->root)) {
            throw new \RuntimeException(sprintf('Unable to create the store directory (%s).', $this->root));
        }
        $this->keyCache = new \SplObjectStorage();
        $this->options = array_merge([
            'private_headers' => ['Set-Cookie'],
        ], $options);
    }

    /**
     * Cleanups storage.
     *
     * @return void
     */
    public function cleanup()
    {
        // unlock everything
        foreach ($this->locks as $lock) {
            flock($lock, \LOCK_UN);
            fclose($lock);
        }

        $this->locks = [];
    }

    /**
     * Tries to lock the cache for a given Request, without blocking.
     *
     * @return bool|string true if the lock is acquired, the path to the current lock otherwise
     */
    public function lock(Request $request): bool|string
    {
        $key = $this->getCacheKey($request);

        if (!isset($this->locks[$key])) {
            $path = $this->getPath($key);
            if (!is_dir(\dirname($path)) && false === @mkdir(\dirname($path), 0777, true) && !is_dir(\dirname($path))) {
                return $path;
            }
            $h = fopen($path, 'c');
            if (!flock($h, \LOCK_EX | \LOCK_NB)) {
                fclose($h);

                return $path;
            }

            $this->locks[$key] = $h;
        }

        return true;
    }

    /**
     * Releases the lock for the given Request.
     *
     * @return bool False if the lock file does not exist or cannot be unlocked, true otherwise
     */
    public function unlock(Request $request): bool
    {
        $key = $this->getCacheKey($request);

        if (isset($this->locks[$key])) {
            flock($this->locks[$key], \LOCK_UN);
            fclose($this->locks[$key]);
            unset($this->locks[$key]);

            return true;
        }

        return false;
    }

    public function isLocked(Request $request): bool
    {
        $key = $this->getCacheKey($request);

        if (isset($this->locks[$key])) {
            return true; // shortcut if lock held by this process
        }

        if (!is_file($path = $this->getPath($key))) {
            return false;
        }

        $h = fopen($path, 'r');
        flock($h, \LOCK_EX | \LOCK_NB, $wouldBlock);
        flock($h, \LOCK_UN); // release the lock we just acquired
        fclose($h);

        return (bool) $wouldBlock;
    }

    /**
     * Locates a cached Response for the Request provided.
     */
    public function lookup(Request $request): ?Response
    {
        $key = $this->getCacheKey($request);

        if (!$entries = $this->getMetadata($key)) {
            return null;
        }

        // find a cached entry that matches the request.
        $match = null;
        foreach ($entries as $entry) {
            if ($this->requestsMatch(isset($entry[1]['vary'][0]) ? implode(', ', $entry[1]['vary']) : '', $request->headers->all(), $entry[0])) {
                $match = $entry;

                break;
            }
        }

        if (null === $match) {
            return null;
        }

        $headers = $match[1];
        if (file_exists($path = $this->getPath($headers['x-content-digest'][0]))) {
            return $this->restoreResponse($headers, $path);
        }

        // TODO the metaStore referenced an entity that doesn't exist in
        // the entityStore. We definitely want to return nil but we should
        // also purge the entry from the meta-store when this is detected.
        return null;
    }

    /**
     * Writes a cache entry to the store for the given Request and Response.
     *
     * Existing entries are read and any that match the response are removed. This
     * method calls write with the new list of cache entries.
     *
     * @throws \RuntimeException
     */
    public function write(Request $request, Response $response): string
    {
        $key = $this->getCacheKey($request);
        $storedEnv = $this->persistRequest($request);

        if ($response->headers->has('X-Body-File')) {
            // Assume the response came from disk, but at least perform some safeguard checks
            if (!$response->headers->has('X-Content-Digest')) {
                throw new \RuntimeException('A restored response must have the X-Content-Digest header.');
            }

            $digest = $response->headers->get('X-Content-Digest');
            if ($this->getPath($digest) !== $response->headers->get('X-Body-File')) {
                throw new \RuntimeException('X-Body-File and X-Content-Digest do not match.');
            }
        // Everything seems ok, omit writing content to disk
        } else {
            $digest = $this->generateContentDigest($response);
            $response->headers->set('X-Content-Digest', $digest);

            if (!$this->save($digest, $response->getContent(), false)) {
                throw new \RuntimeException('Unable to store the entity.');
            }

            if (!$response->headers->has('Transfer-Encoding')) {
                $response->headers->set('Content-Length', \strlen($response->getContent()));
            }
        }

        // read existing cache entries, remove non-varying, and add this one to the list
        $entries = [];
        $vary = $response->headers->get('vary');
        foreach ($this->getMetadata($key) as $entry) {
            if (!isset($entry[1]['vary'][0])) {
                $entry[1]['vary'] = [''];
            }

            if ($entry[1]['vary'][0] != $vary || !$this->requestsMatch($vary ?? '', $entry[0], $storedEnv)) {
                $entries[] = $entry;
            }
        }

        $headers = $this->persistResponse($response);
        unset($headers['age']);

        foreach ($this->options['private_headers'] as $h) {
            unset($headers[strtolower($h)]);
        }

        array_unshift($entries, [$storedEnv, $headers]);

        if (!$this->save($key, serialize($entries))) {
            throw new \RuntimeException('Unable to store the metadata.');
        }

        return $key;
    }

    /**
     * Returns content digest for $response.
     */
    protected function generateContentDigest(Response $response): string
    {
        return 'en'.hash('xxh128', $response->getContent());
    }

    /**
     * Invalidates all cache entries that match the request.
     *
     * @return void
     *
     * @throws \RuntimeException
     */
    public function invalidate(Request $request)
    {
        $modified = false;
        $key = $this->getCacheKey($request);

        $entries = [];
        foreach ($this->getMetadata($key) as $entry) {
            $response = $this->restoreResponse($entry[1]);
            if ($response->isFresh()) {
                $response->expire();
                $modified = true;
                $entries[] = [$entry[0], $this->persistResponse($response)];
            } else {
                $entries[] = $entry;
            }
        }

        if ($modified && !$this->save($key, serialize($entries))) {
            throw new \RuntimeException('Unable to store the metadata.');
        }
    }

    /**
     * Determines whether two Request HTTP header sets are non-varying based on
     * the vary response header value provided.
     *
     * @param string|null $vary A Response vary header
     * @param array       $env1 A Request HTTP header array
     * @param array       $env2 A Request HTTP header array
     */
    private function requestsMatch(?string $vary, array $env1, array $env2): bool
    {
        if (empty($vary)) {
            return true;
        }

        foreach (preg_split('/[\s,]+/', $vary) as $header) {
            $key = str_replace('_', '-', strtolower($header));
            $v1 = $env1[$key] ?? null;
            $v2 = $env2[$key] ?? null;
            if ($v1 !== $v2) {
                return false;
            }
        }

        return true;
    }

    /**
     * Gets all data associated with the given key.
     *
     * Use this method only if you know what you are doing.
     */
    private function getMetadata(string $key): array
    {
        if (!$entries = $this->load($key)) {
            return [];
        }

        return unserialize($entries) ?: [];
    }

    /**
     * Purges data for the given URL.
     *
     * This method purges both the HTTP and the HTTPS version of the cache entry.
     *
     * @return bool true if the URL exists with either HTTP or HTTPS scheme and has been purged, false otherwise
     */
    public function purge(string $url): bool
    {
        $http = preg_replace('#^https:#', 'http:', $url);
        $https = preg_replace('#^http:#', 'https:', $url);

        $purgedHttp = $this->doPurge($http);
        $purgedHttps = $this->doPurge($https);

        return $purgedHttp || $purgedHttps;
    }

    /**
     * Purges data for the given URL.
     */
    private function doPurge(string $url): bool
    {
        $key = $this->getCacheKey(Request::create($url));
        if (isset($this->locks[$key])) {
            flock($this->locks[$key], \LOCK_UN);
            fclose($this->locks[$key]);
            unset($this->locks[$key]);
        }

        if (is_file($path = $this->getPath($key))) {
            unlink($path);

            return true;
        }

        return false;
    }

    /**
     * Loads data for the given key.
     */
    private function load(string $key): ?string
    {
        $path = $this->getPath($key);

        return is_file($path) && false !== ($contents = @file_get_contents($path)) ? $contents : null;
    }

    /**
     * Save data for the given key.
     */
    private function save(string $key, string $data, bool $overwrite = true): bool
    {
        $path = $this->getPath($key);

        if (!$overwrite && file_exists($path)) {
            return true;
        }

        if (isset($this->locks[$key])) {
            $fp = $this->locks[$key];
            @ftruncate($fp, 0);
            @fseek($fp, 0);
            $len = @fwrite($fp, $data);
            if (\strlen($data) !== $len) {
                @ftruncate($fp, 0);

                return false;
            }
        } else {
            if (!is_dir(\dirname($path)) && false === @mkdir(\dirname($path), 0777, true) && !is_dir(\dirname($path))) {
                return false;
            }

            $tmpFile = tempnam(\dirname($path), basename($path));
            if (false === $fp = @fopen($tmpFile, 'w')) {
                @unlink($tmpFile);

                return false;
            }
            @fwrite($fp, $data);
            @fclose($fp);

            if ($data != file_get_contents($tmpFile)) {
                @unlink($tmpFile);

                return false;
            }

            if (false === @rename($tmpFile, $path)) {
                @unlink($tmpFile);

                return false;
            }
        }

        @chmod($path, 0666 & ~umask());

        return true;
    }

    /**
     * @return string
     */
    public function getPath(string $key)
    {
        return $this->root.\DIRECTORY_SEPARATOR.substr($key, 0, 2).\DIRECTORY_SEPARATOR.substr($key, 2, 2).\DIRECTORY_SEPARATOR.substr($key, 4, 2).\DIRECTORY_SEPARATOR.substr($key, 6);
    }

    /**
     * Generates a cache key for the given Request.
     *
     * This method should return a key that must only depend on a
     * normalized version of the request URI.
     *
     * If the same URI can have more than one representation, based on some
     * headers, use a Vary header to indicate them, and each representation will
     * be stored independently under the same cache key.
     */
    protected function generateCacheKey(Request $request): string
    {
        return 'md'.hash('sha256', $request->getUri());
    }

    /**
     * Returns a cache key for the given Request.
     */
    private function getCacheKey(Request $request): string
    {
        if (isset($this->keyCache[$request])) {
            return $this->keyCache[$request];
        }

        return $this->keyCache[$request] = $this->generateCacheKey($request);
    }

    /**
     * Persists the Request HTTP headers.
     */
    private function persistRequest(Request $request): array
    {
        return $request->headers->all();
    }

    /**
     * Persists the Response HTTP headers.
     */
    private function persistResponse(Response $response): array
    {
        $headers = $response->headers->all();
        $headers['X-Status'] = [$response->getStatusCode()];

        return $headers;
    }

    /**
     * Restores a Response from the HTTP headers and body.
     */
    private function restoreResponse(array $headers, ?string $path = null): ?Response
    {
        $status = $headers['X-Status'][0];
        unset($headers['X-Status']);
        $content = null;

        if (null !== $path) {
            $headers['X-Body-File'] = [$path];
            unset($headers['x-body-file']);

            if ($headers['X-Body-Eval'] ?? $headers['x-body-eval'] ?? false) {
                $content = file_get_contents($path);
                \assert(HttpCache::BODY_EVAL_BOUNDARY_LENGTH === 24);
                if (48 > \strlen($content) || substr($content, -24) !== substr($content, 0, 24)) {
                    return null;
                }
            }
        }

        return new Response($content, $status, $headers);
    }
}

© 2025 UnknownSec
Web Design for Beginners | Anyleson - Learning Platform
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Web Design for Beginners

Web Design for Beginners

in Design
Created by Linda Anderson
+2
5 Users are following this upcoming course
Course Published
This course was published already and you can check the main course
Course
Web Design for Beginners
in Design
4.25
1:45 Hours
8 Jul 2021
₹11.80

What you will learn?

Create any website layout you can imagine

Support any device size with Responsive (mobile-friendly) Design

Add tasteful animations and effects with CSS3

Course description

You can launch a new career in web development today by learning HTML & CSS. You don't need a computer science degree or expensive software. All you need is a computer, a bit of time, a lot of determination, and a teacher you trust. I've taught HTML and CSS to countless coworkers and held training sessions for fortune 100 companies. I am that teacher you can trust. 


Don't limit yourself by creating websites with some cheesy “site-builder" tool. This course teaches you how to take 100% control over your webpages by using the same concepts that every professional website is created with.


This course does not assume any prior experience. We start at square one and learn together bit by bit. By the end of the course you will have created (by hand) a website that looks great on phones, tablets, laptops, and desktops alike.


In the summer of 2020 the course has received a new section where we push our website live up onto the web using the free GitHub Pages service; this means you'll be able to share a link to what you've created with your friends, family, colleagues and the world!

Requirements

No prerequisite knowledge required

No special software required

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