Viewing file:  SignalHandler.php (3.15 KB) -rw-r--r--
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<?php
/*
* This file is part of Psy Shell.
*
* (c) 2012-2025 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\Exception\InterruptException;
use Psy\Shell;
use Psy\Util\DependencyChecker;
/**
* A signal handler for interrupting execution with Ctrl-C, used when process forking is disabled.
*/
class SignalHandler extends AbstractListener
{
private bool $sigintHandlerInstalled = false;
private bool $restoreStty = false;
private bool $wasInterrupted = false;
public const PCNTL_FUNCTIONS = [
'pcntl_signal',
'pcntl_async_signals',
];
public const POSIX_FUNCTIONS = [
'posix_isatty',
];
/**
* Signal handler is supported if pcntl and posix extensions are available.
*/
public static function isSupported(): bool
{
return DependencyChecker::functionsAvailable(self::PCNTL_FUNCTIONS)
&& DependencyChecker::functionsAvailable(self::POSIX_FUNCTIONS);
}
/**
* Install SIGINT handler before executing user code.
*/
public function onExecute(Shell $shell, string $code)
{
$this->wasInterrupted = false;
// Ensure signal processing is enabled so Ctrl-C can interrupt execution
if (@\posix_isatty(\STDIN)) {
@\shell_exec('stty isig 2>/dev/null');
$this->restoreStty = true;
}
\pcntl_async_signals(true);
// Install SIGINT handler that throws exception during execution
$interrupted = &$this->wasInterrupted;
$this->sigintHandlerInstalled = \pcntl_signal(\SIGINT, function () use (&$interrupted) {
$interrupted = true;
throw new InterruptException('Ctrl+C');
});
return null;
}
/**
* Called at the end of each loop.
*
* Restores terminal state and clears stdin if execution was interrupted.
*/
public function afterLoop(Shell $shell)
{
// Restore default SIGINT handler after execution
if ($this->sigintHandlerInstalled) {
\pcntl_signal(\SIGINT, \SIG_DFL);
$this->sigintHandlerInstalled = false;
}
// Restore terminal to raw mode after execution
// This prevents Ctrl-C at the prompt from generating SIGINT
if ($this->restoreStty) {
@\shell_exec('stty -isig 2>/dev/null');
$this->restoreStty = false;
}
// Clear any pending input from the interrupted stdin stream
// The SIGINT may have left the stream in a bad state
if ($this->wasInterrupted && \defined('STDIN') && \is_resource(\STDIN)) {
// Check if the stream is still usable
$meta = @\stream_get_meta_data(\STDIN);
if ($meta && !($meta['eof'] ?? false)) {
// Drain any buffered input, suppressing I/O errors
@\stream_set_blocking(\STDIN, false);
while (@\fgetc(\STDIN) !== false) {
}
@\stream_set_blocking(\STDIN, true);
}
$this->wasInterrupted = false;
}
}
}
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