Viewing file:  TerminalInputHelper.php (4.29 KB) -rw-r--r--
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<?php
/*
* This file is part of the Symfony package.
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Symfony\Component\Console\Helper;
/**
* TerminalInputHelper stops Ctrl-C and similar signals from leaving the terminal in
* an unusable state if its settings have been modified when reading user input.
* This can be an issue on non-Windows platforms.
*
* Usage:
*
* $inputHelper = new TerminalInputHelper($inputStream);
*
* ...change terminal settings
*
* // Wait for input before all input reads
* $inputHelper->waitForInput();
*
* ...read input
*
* // Call finish to restore terminal settings and signal handlers
* $inputHelper->finish()
*
* @internal
*/
final class TerminalInputHelper
{
/** @var resource */
private $inputStream;
private bool $isStdin;
private string $initialState;
private int $signalToKill = 0;
private array $signalHandlers = [];
private array $targetSignals = [];
/**
* @param resource $inputStream
*
* @throws \RuntimeException If unable to read terminal settings
*/
public function __construct($inputStream)
{
if (!\is_string($state = shell_exec('stty -g'))) {
throw new \RuntimeException('Unable to read the terminal settings.');
}
$this->inputStream = $inputStream;
$this->initialState = $state;
$this->isStdin = 'php://stdin' === stream_get_meta_data($inputStream)['uri'];
$this->createSignalHandlers();
}
/**
* Waits for input and terminates if sent a default signal.
*/
public function waitForInput(): void
{
if ($this->isStdin) {
$r = [$this->inputStream];
$w = [];
// Allow signal handlers to run, either before Enter is pressed
// when icanon is enabled, or a single character is entered when
// icanon is disabled
while (0 === @stream_select($r, $w, $w, 0, 100)) {
$r = [$this->inputStream];
}
}
$this->checkForKillSignal();
}
/**
* Restores terminal state and signal handlers.
*/
public function finish(): void
{
// Safeguard in case an unhandled kill signal exists
$this->checkForKillSignal();
shell_exec('stty '.$this->initialState);
$this->signalToKill = 0;
foreach ($this->signalHandlers as $signal => $originalHandler) {
pcntl_signal($signal, $originalHandler);
}
$this->signalHandlers = [];
$this->targetSignals = [];
}
private function createSignalHandlers(): void
{
if (!\function_exists('pcntl_async_signals') || !\function_exists('pcntl_signal')) {
return;
}
pcntl_async_signals(true);
$this->targetSignals = [\SIGINT, \SIGQUIT, \SIGTERM];
foreach ($this->targetSignals as $signal) {
$this->signalHandlers[$signal] = pcntl_signal_get_handler($signal);
pcntl_signal($signal, function ($signal) {
// Save current state, then restore to initial state
$currentState = shell_exec('stty -g');
shell_exec('stty '.$this->initialState);
$originalHandler = $this->signalHandlers[$signal];
if (\is_callable($originalHandler)) {
$originalHandler($signal);
// Handler did not exit, so restore to current state
shell_exec('stty '.$currentState);
return;
}
// Not a callable, so SIG_DFL or SIG_IGN
if (\SIG_DFL === $originalHandler) {
$this->signalToKill = $signal;
}
});
}
}
private function checkForKillSignal(): void
{
if (\in_array($this->signalToKill, $this->targetSignals, true)) {
// Try posix_kill
if (\function_exists('posix_kill')) {
pcntl_signal($this->signalToKill, \SIG_DFL);
posix_kill(getmypid(), $this->signalToKill);
}
// Best attempt fallback
exit(128 + $this->signalToKill);
}
}
}
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