function NativeSessionStorage::start

Overrides SessionStorageInterface::start

4 calls to NativeSessionStorage::start()

NativeSessionStorage::getBag in vendor/symfony/http-foundation/Session/Storage/NativeSessionStorage.php: Gets a SessionBagInterface by name.
NativeSessionStorage::regenerate in vendor/symfony/http-foundation/Session/Storage/NativeSessionStorage.php: Regenerates id that represents this storage.
SessionManager::startNow in core/lib/Drupal/Core/Session/SessionManager.php: Forcibly start a PHP session.
SessionManager::startNow in core/lib/Drupal/Core/Session/SessionManager.php: Forcibly start a PHP session.

2 methods override NativeSessionStorage::start()

PhpBridgeSessionStorage::start in vendor/symfony/http-foundation/Session/Storage/PhpBridgeSessionStorage.php: Starts the session.
SessionManager::start in core/lib/Drupal/Core/Session/SessionManager.php: Starts the session.

File

vendor/symfony/http-foundation/Session/Storage/NativeSessionStorage.php, line 105

Class

NativeSessionStorage: This provides a base class for session attribute storage.

Namespace

Symfony\Component\HttpFoundation\Session\Storage

Code

public function start() : bool {
    if ($this->started) {
        return true;
    }
    if (\PHP_SESSION_ACTIVE === session_status()) {
        throw new \RuntimeException('Failed to start the session: already started by PHP.');
    }
    if (filter_var(\ini_get('session.use_cookies'), \FILTER_VALIDATE_BOOL) && headers_sent($file, $line)) {
        throw new \RuntimeException(\sprintf('Failed to start the session because headers have already been sent by "%s" at line %d.', $file, $line));
    }
    $sessionId = $_COOKIE[session_name()] ?? null;
    
    /*
     * Explanation of the session ID regular expression: `/^[a-zA-Z0-9,-]{22,250}$/`.
     *
     * ---------- Part 1
     *
     * The part `[a-zA-Z0-9,-]` is related to the PHP ini directive `session.sid_bits_per_character` defined as 6.
     * See https://www.php.net/manual/en/session.configuration.php#ini.session.sid-bits-per-character.
     * Allowed values are integers such as:
     * - 4 for range `a-f0-9`
     * - 5 for range `a-v0-9` (@deprecated since Symfony 7.2, it will default to 4 and the option will be ignored in Symfony 8.0)
     * - 6 for range `a-zA-Z0-9,-` (@deprecated since Symfony 7.2, it will default to 4 and the option will be ignored in Symfony 8.0)
     *
     * ---------- Part 2
     *
     * The part `{22,250}` is related to the PHP ini directive `session.sid_length`.
     * See https://www.php.net/manual/en/session.configuration.php#ini.session.sid-length.
     * Allowed values are integers between 22 and 256, but we use 250 for the max.
     *
     * Where does the 250 come from?
     * - The length of Windows and Linux filenames is limited to 255 bytes. Then the max must not exceed 255.
     * - The session filename prefix is `sess_`, a 5 bytes string. Then the max must not exceed 255 - 5 = 250.
     *
     * This is @deprecated since Symfony 7.2, the sid length will default to 32 and the option will be ignored in Symfony 8.0.
     *
     * ---------- Conclusion
     *
     * The parts 1 and 2 prevent the warning below:
     * `PHP Warning: SessionHandler::read(): Session ID is too long or contains illegal characters. Only the A-Z, a-z, 0-9, "-", and "," characters are allowed.`
     *
     * The part 2 prevents the warning below:
     * `PHP Warning: SessionHandler::read(): open(filepath, O_RDWR) failed: No such file or directory (2).`
     */
    if ($sessionId && $this->saveHandler instanceof AbstractProxy && 'files' === $this->saveHandler
        ->getSaveHandlerName() && !preg_match('/^[a-zA-Z0-9,-]{22,250}$/', $sessionId)) {
        // the session ID in the header is invalid, create a new one
        session_id(session_create_id());
    }
    // ok to try and start the session
    if (!session_start()) {
        throw new \RuntimeException('Failed to start the session.');
    }
    $this->loadSession();
    return true;
}