name : ProcessForker.php <?php /* * This file is part of Psy Shell. * * (c) 2012-2023 Justin Hileman * * For the full copyright and license information, please view the LICENSE * file that was distributed with this source code. */ namespace Psy\ExecutionLoop; use Psy\Context; use Psy\Exception\BreakException; use Psy\Shell; /** * An execution loop listener that forks the process before executing code. * * This is awesome, as the session won't die prematurely if user input includes * a fatal error, such as redeclaring a class or function. */ class ProcessForker extends AbstractListener { private $savegame; private $up; private static $pcntlFunctions = [ 'pcntl_fork', 'pcntl_signal_dispatch', 'pcntl_signal', 'pcntl_waitpid', 'pcntl_wexitstatus', ]; private static $posixFunctions = [ 'posix_getpid', 'posix_kill', ]; /** * Process forker is supported if pcntl and posix extensions are available. */ public static function isSupported(): bool { return self::isPcntlSupported() && !self::disabledPcntlFunctions() && self::isPosixSupported() && !self::disabledPosixFunctions(); } /** * Verify that all required pcntl functions are, in fact, available. */ public static function isPcntlSupported(): bool { foreach (self::$pcntlFunctions as $func) { if (!\function_exists($func)) { return false; } } return true; } /** * Check whether required pcntl functions are disabled. */ public static function disabledPcntlFunctions() { return self::checkDisabledFunctions(self::$pcntlFunctions); } /** * Verify that all required posix functions are, in fact, available. */ public static function isPosixSupported(): bool { foreach (self::$posixFunctions as $func) { if (!\function_exists($func)) { return false; } } return true; } /** * Check whether required posix functions are disabled. */ public static function disabledPosixFunctions() { return self::checkDisabledFunctions(self::$posixFunctions); } private static function checkDisabledFunctions(array $functions): array { return \array_values(\array_intersect($functions, \array_map('strtolower', \array_map('trim', \explode(',', \ini_get('disable_functions')))))); } /** * Forks into a main and a loop process. * * The loop process will handle the evaluation of all instructions, then * return its state via a socket upon completion. * * @param Shell $shell */ public function beforeRun(Shell $shell) { list($up, $down) = \stream_socket_pair(\STREAM_PF_UNIX, \STREAM_SOCK_STREAM, \STREAM_IPPROTO_IP); if (!$up) { throw new \RuntimeException('Unable to create socket pair'); } $pid = \pcntl_fork(); if ($pid < 0) { throw new \RuntimeException('Unable to start execution loop'); } elseif ($pid > 0) { // This is the main thread. We'll just wait for a while. // We won't be needing this one. \fclose($up); // Wait for a return value from the loop process. $read = [$down]; $write = null; $except = null; do { $n = @\stream_select($read, $write, $except, null); if ($n === 0) { throw new \RuntimeException('Process timed out waiting for execution loop'); } if ($n === false) { $err = \error_get_last(); if (!isset($err['message']) || \stripos($err['message'], 'interrupted system call') === false) { $msg = $err['message'] ? \sprintf('Error waiting for execution loop: %s', $err['message']) : 'Error waiting for execution loop'; throw new \RuntimeException($msg); } } } while ($n < 1); $content = \stream_get_contents($down); \fclose($down); if ($content) { $shell->setScopeVariables(@\unserialize($content)); } throw new BreakException('Exiting main thread'); } // This is the child process. It's going to do all the work. if (!@\cli_set_process_title('psysh (loop)')) { // Fall back to `setproctitle` if that wasn't succesful. if (\function_exists('setproctitle')) { @\setproctitle('psysh (loop)'); } } // We won't be needing this one. \fclose($down); // Save this; we'll need to close it in `afterRun` $this->up = $up; } /** * Create a savegame at the start of each loop iteration. * * @param Shell $shell */ public function beforeLoop(Shell $shell) { $this->createSavegame(); } /** * Clean up old savegames at the end of each loop iteration. * * @param Shell $shell */ public function afterLoop(Shell $shell) { // if there's an old savegame hanging around, let's kill it. if (isset($this->savegame)) { \posix_kill($this->savegame, \SIGKILL); \pcntl_signal_dispatch(); } } /** * After the REPL session ends, send the scope variables back up to the main * thread (if this is a child thread). * * @param Shell $shell */ public function afterRun(Shell $shell) { // We're a child thread. Send the scope variables back up to the main thread. if (isset($this->up)) { \fwrite($this->up, $this->serializeReturn($shell->getScopeVariables(false))); \fclose($this->up); \posix_kill(\posix_getpid(), \SIGKILL); } } /** * Create a savegame fork. * * The savegame contains the current execution state, and can be resumed in * the event that the worker dies unexpectedly (for example, by encountering * a PHP fatal error). */ private function createSavegame() { // the current process will become the savegame $this->savegame = \posix_getpid(); $pid = \pcntl_fork(); if ($pid < 0) { throw new \RuntimeException('Unable to create savegame fork'); } elseif ($pid > 0) { // we're the savegame now... let's wait and see what happens \pcntl_waitpid($pid, $status); // worker exited cleanly, let's bail if (!\pcntl_wexitstatus($status)) { \posix_kill(\posix_getpid(), \SIGKILL); } // worker didn't exit cleanly, we'll need to have another go $this->createSavegame(); } } /** * Serialize all serializable return values. * * A naïve serialization will run into issues if there is a Closure or * SimpleXMLElement (among other things) in scope when exiting the execution * loop. We'll just ignore these unserializable classes, and serialize what * we can. * * @param array $return */ private function serializeReturn(array $return): string { $serializable = []; foreach ($return as $key => $value) { // No need to return magic variables if (Context::isSpecialVariableName($key)) { continue; } // Resources and Closures don't error, but they don't serialize well either. if (\is_resource($value) || $value instanceof \Closure) { continue; } if (\version_compare(\PHP_VERSION, '8.1', '>=') && $value instanceof \UnitEnum) { // Enums defined in the REPL session can't be unserialized. $ref = new \ReflectionObject($value); if (\strpos($ref->getFileName(), ": eval()'d code") !== false) { continue; } } try { @\serialize($value); $serializable[$key] = $value; } catch (\Throwable $e) { // we'll just ignore this one... } } return @\serialize($serializable); } }