430 lines
14 KiB
PHP
430 lines
14 KiB
PHP
<?php
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/*
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* This file is part of Psy Shell.
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*
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* (c) 2012-2025 Justin Hileman
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Psy\ExecutionLoop;
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use Psy\Context;
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use Psy\Exception\BreakException;
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use Psy\Exception\InterruptException;
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use Psy\Shell;
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use Psy\Util\DependencyChecker;
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/**
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* An execution loop listener that forks the process before executing code.
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*
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* This is awesome, as the session won't die prematurely if user input includes
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* a fatal error, such as redeclaring a class or function.
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*/
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class ProcessForker extends AbstractListener
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{
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private ?int $savegame = null;
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/** @var resource */
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private $up;
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private bool $sigintHandlerInstalled = false;
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private bool $restoreStty = false;
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private ?string $originalStty = null;
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public const PCNTL_FUNCTIONS = [
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'pcntl_fork',
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'pcntl_signal_dispatch',
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'pcntl_signal',
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'pcntl_waitpid',
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'pcntl_wexitstatus',
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];
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public const POSIX_FUNCTIONS = [
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'posix_getpid',
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'posix_kill',
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];
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/**
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* Process forker is supported if pcntl and posix extensions are available.
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*/
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public static function isSupported(): bool
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{
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return DependencyChecker::functionsAvailable(self::PCNTL_FUNCTIONS)
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&& DependencyChecker::functionsAvailable(self::POSIX_FUNCTIONS);
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}
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/**
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* Verify that all required pcntl functions are, in fact, available.
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*
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* @deprecated
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*/
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public static function isPcntlSupported(): bool
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{
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return DependencyChecker::functionsAvailable(self::PCNTL_FUNCTIONS);
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}
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/**
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* Check whether required pcntl functions are disabled.
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*
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* @deprecated
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*/
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public static function disabledPcntlFunctions()
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{
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return DependencyChecker::functionsDisabled(self::PCNTL_FUNCTIONS);
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}
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/**
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* Verify that all required posix functions are, in fact, available.
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*
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* @deprecated
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*/
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public static function isPosixSupported(): bool
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{
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return DependencyChecker::functionsAvailable(self::POSIX_FUNCTIONS);
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}
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/**
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* Check whether required posix functions are disabled.
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*
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* @deprecated
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*/
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public static function disabledPosixFunctions()
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{
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return DependencyChecker::functionsDisabled(self::POSIX_FUNCTIONS);
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}
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/**
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* Forks into a main and a loop process.
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*
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* The loop process will handle the evaluation of all instructions, then
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* return its state via a socket upon completion.
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*
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* @param Shell $shell
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*/
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public function beforeRun(Shell $shell)
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{
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// Temporarily disable socket timeout for IPC sockets, to avoid losing our child process
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// communication after 60 seconds.
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$originalTimeout = @\ini_set('default_socket_timeout', '-1');
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list($up, $down) = \stream_socket_pair(\STREAM_PF_UNIX, \STREAM_SOCK_STREAM, \STREAM_IPPROTO_IP);
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if ($originalTimeout !== false) {
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@\ini_set('default_socket_timeout', $originalTimeout);
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}
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if (!$up) {
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throw new \RuntimeException('Unable to create socket pair');
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}
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$pid = \pcntl_fork();
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if ($pid < 0) {
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throw new \RuntimeException('Unable to start execution loop');
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} elseif ($pid > 0) {
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// This is the main (parent) process. Install SIGINT handler and wait for child.
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// We won't be needing this one.
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\fclose($up);
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// Install SIGINT handler in parent to interrupt child
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\pcntl_async_signals(true);
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$interrupted = false;
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$sigintHandlerInstalled = \pcntl_signal(\SIGINT, function () use (&$interrupted, $pid) {
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$interrupted = true;
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// Send SIGINT to child so it can handle interruption gracefully
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\posix_kill($pid, \SIGINT);
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});
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// Wait for a return value from the loop process.
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$read = [$down];
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$write = null;
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$except = null;
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do {
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if ($interrupted) {
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// Wait for child to exit (it should handle SIGINT gracefully)
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\pcntl_waitpid($pid, $status);
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// Try to read any final output from child before it exited
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$content = @\stream_get_contents($down);
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\fclose($down);
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if ($sigintHandlerInstalled) {
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\pcntl_signal(\SIGINT, \SIG_DFL);
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}
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$this->clearStdinBuffer();
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// Restore scope variables and exit code if child sent any
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// If child didn't send data, use the actual process exit status
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$exitCode = \pcntl_wexitstatus($status);
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if ($content) {
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$data = @\unserialize($content);
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if (\is_array($data) && isset($data['exitCode'], $data['scopeVars'])) {
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$exitCode = $data['exitCode'];
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$shell->setScopeVariables($data['scopeVars']);
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}
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}
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throw new BreakException('Exiting main thread', $exitCode);
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}
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$n = @\stream_select($read, $write, $except, null);
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if ($n === 0) {
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throw new \RuntimeException('Process timed out waiting for execution loop');
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}
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if ($n === false) {
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$err = \error_get_last();
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$errMessage = \is_array($err) ? ($err['message'] ?? null) : null;
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// If there's no error message, or it's an interrupted system call, just retry
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if ($errMessage === null || \stripos($errMessage, 'interrupted system call') !== false) {
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continue;
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}
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throw new \RuntimeException(\sprintf('Error waiting for execution loop: %s', $errMessage));
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}
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} while ($n < 1);
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$content = \stream_get_contents($down);
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\fclose($down);
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// Wait for child to exit and get its exit status
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\pcntl_waitpid($pid, $status);
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// Restore default SIGINT handler
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if ($sigintHandlerInstalled) {
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\pcntl_signal(\SIGINT, \SIG_DFL);
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}
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// If child didn't send data, use the actual process exit status
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$exitCode = \pcntl_wexitstatus($status);
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if ($content) {
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$data = @\unserialize($content);
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if (\is_array($data) && isset($data['exitCode'], $data['scopeVars'])) {
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$exitCode = $data['exitCode'];
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$shell->setScopeVariables($data['scopeVars']);
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}
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}
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throw new BreakException('Exiting main thread', $exitCode);
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}
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// This is the child process. It's going to do all the work.
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if (!@\cli_set_process_title('psysh (loop)')) {
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// Fall back to `setproctitle` if that wasn't succesful.
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if (\function_exists('setproctitle')) {
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@\setproctitle('psysh (loop)');
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}
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}
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// We won't be needing this one.
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\fclose($down);
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// Save this; we'll need to close it in `afterRun`
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$this->up = $up;
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// Save original stty state so we can restore on exit
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if (@\posix_isatty(\STDIN)) {
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$this->originalStty = @\shell_exec('stty -g 2>/dev/null');
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}
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}
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/**
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* Install SIGINT handler before executing user code.
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*/
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public function onExecute(Shell $shell, string $code)
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{
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// Only handle SIGINT in the child process
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if (isset($this->up)) {
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// Ensure signal processing is enabled so Ctrl-C can interrupt execution
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if (@\posix_isatty(\STDIN)) {
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@\shell_exec('stty isig 2>/dev/null');
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$this->restoreStty = true;
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}
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\pcntl_async_signals(true);
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// Install SIGINT handler that throws exception during execution
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\pcntl_signal(\SIGINT, function () {
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throw new InterruptException('Ctrl+C');
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});
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}
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return null;
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}
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/**
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* Create a savegame at the start of each loop iteration.
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*
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* @param Shell $shell
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*/
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public function beforeLoop(Shell $shell)
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{
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$this->createSavegame();
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}
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/**
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* Clean up old savegames at the end of each loop iteration.
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*
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* Restores terminal state and clears stdin if execution was interrupted.
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*/
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public function afterLoop(Shell $shell)
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{
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// Only handle cleanup in child process
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if (isset($this->up)) {
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// Restore default SIGINT handler after execution
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if (!$this->sigintHandlerInstalled) {
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\pcntl_signal(\SIGINT, \SIG_DFL);
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}
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// Restore terminal to raw mode after execution
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// This prevents Ctrl-C at the prompt from generating SIGINT
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if ($this->restoreStty) {
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@\shell_exec('stty -isig 2>/dev/null');
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$this->restoreStty = false;
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}
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}
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// if there's an old savegame hanging around, let's kill it.
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if (isset($this->savegame)) {
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\posix_kill($this->savegame, \SIGKILL);
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\pcntl_signal_dispatch();
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}
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}
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/**
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* After the REPL session ends, send the scope variables back up to the main
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* thread (if this is a child thread).
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*
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* {@inheritdoc}
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*/
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public function afterRun(Shell $shell, int $exitCode = 0)
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{
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// We're a child thread. Send the scope variables and exit code back up to the main thread.
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if (isset($this->up)) {
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$data = $this->serializeReturn($exitCode, $shell->getScopeVariables(false));
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// Suppress errors in case the pipe is broken (e.g., if parent was interrupted)
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@\fwrite($this->up, $data);
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@\fclose($this->up);
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// Restore original terminal state before exiting.
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//
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// We set `stty isig` during execution, so Ctrl-C can interrupt, and
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// `stty -isig` after, so readline can handle it at the prompt.
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// Let's put things back the way we found them.
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if ($this->originalStty !== null) {
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@\shell_exec('stty '.\escapeshellarg(\trim($this->originalStty)).' 2>/dev/null');
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}
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\posix_kill(\posix_getpid(), \SIGKILL);
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}
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}
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/**
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* Create a savegame fork.
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*
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* The savegame contains the current execution state, and can be resumed in
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* the event that the worker dies unexpectedly (for example, by encountering
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* a PHP fatal error).
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*/
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private function createSavegame()
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{
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// the current process will become the savegame
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$this->savegame = \posix_getpid();
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$pid = \pcntl_fork();
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if ($pid < 0) {
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throw new \RuntimeException('Unable to create savegame fork');
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} elseif ($pid > 0) {
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// we're the savegame now... let's wait and see what happens
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\pcntl_waitpid($pid, $status);
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// worker exited cleanly, let's bail
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if (!\pcntl_wexitstatus($status)) {
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\posix_kill(\posix_getpid(), \SIGKILL);
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}
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// worker didn't exit cleanly, we'll need to have another go
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// @phan-suppress-next-line PhanPossiblyInfiniteRecursionSameParams - recursion exits via posix_kill above
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$this->createSavegame();
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}
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}
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/**
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* Clear stdin buffer after interruption, in case SIGINT left the stream in a bad state.
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*/
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private function clearStdinBuffer(): void
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{
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if (!\defined('STDIN') || !\is_resource(\STDIN)) {
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return;
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}
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// Check if the stream is still usable
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$meta = @\stream_get_meta_data(\STDIN);
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if (!$meta || ($meta['eof'] ?? false)) {
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return;
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}
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// Drain any buffered input, suppressing I/O errors
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@\stream_set_blocking(\STDIN, false);
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while (@\fgetc(\STDIN) !== false) {
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}
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@\stream_set_blocking(\STDIN, true);
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}
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/**
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* Serialize exit code and scope variables for transmission to parent process.
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*
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* A naïve serialization will run into issues if there is a Closure or
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* SimpleXMLElement (among other things) in scope when exiting the execution
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* loop. We'll just ignore these unserializable classes, and serialize what
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* we can.
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*
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* @param int $exitCode Exit code from the child process
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* @param array $scopeVars Scope variables to serialize
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*
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* @return string Serialized data array containing exitCode and scopeVars
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*/
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private function serializeReturn(int $exitCode, array $scopeVars): string
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{
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$serializable = [];
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foreach ($scopeVars as $key => $value) {
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// No need to return magic variables
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if (Context::isSpecialVariableName($key)) {
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continue;
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}
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// Resources and Closures don't error, but they don't serialize well either.
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if (\is_resource($value) || $value instanceof \Closure) {
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continue;
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}
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if (\PHP_VERSION_ID >= 80100 && $value instanceof \UnitEnum) {
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// Enums defined in the REPL session can't be unserialized.
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$ref = new \ReflectionObject($value);
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if (\strpos($ref->getFileName(), ": eval()'d code") !== false) {
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continue;
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}
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}
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try {
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@\serialize($value);
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$serializable[$key] = $value;
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} catch (\Throwable $e) {
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// we'll just ignore this one...
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}
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}
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return @\serialize([
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'exitCode' => $exitCode,
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'scopeVars' => $serializable,
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]);
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}
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}
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