Handle signals on text input

Author: valx76

Helper/QuestionHelper.php

@@ -437,9 +437,7 @@ private function getHiddenResponse(OutputInterface $output, $inputStream, bool $
             throw new RuntimeException('Unable to hide the response.');
         }
 
-        $inputHelper?->waitForInput();
-
-        $value = fgets($inputStream, 4096);
+        $value = $this->doReadInput($inputStream, helper: $inputHelper);
 
         if (4095 === \strlen($value)) {
             $errOutput = $output instanceof ConsoleOutputInterface ? $output->getErrorOutput() : $output;
@@ -449,9 +447,6 @@ private function getHiddenResponse(OutputInterface $output, $inputStream, bool $
         // Restore the terminal so it behaves normally again
         $inputHelper?->finish();
 
-        if (false === $value) {
-            throw new MissingInputException('Aborted.');
-        }
         if ($trimmable) {
             $value = trim($value);
         }
@@ -511,7 +506,7 @@ private function readInput($inputStream, Question $question): string|false
     {
         if (!$question->isMultiline()) {
             $cp = $this->setIOCodepage();
-            $ret = fgets($inputStream, 4096);
+            $ret = $this->doReadInput($inputStream);
 
             return $this->resetIOCodepage($cp, $ret);
         }
@@ -521,14 +516,8 @@ private function readInput($inputStream, Question $question): string|false
             return false;
         }
 
-        $ret = '';
         $cp = $this->setIOCodepage();
-        while (false !== ($char = fgetc($multiLineStreamReader))) {
-            if ("\x4" === $char || \PHP_EOL === "{$ret}{$char}") {
-                break;
-            }
-            $ret .= $char;
-        }
+        $ret = $this->doReadInput($multiLineStreamReader, "\x4");
 
         if (stream_get_meta_data($inputStream)['seekable']) {
             fseek($inputStream, ftell($multiLineStreamReader));
@@ -598,4 +587,35 @@ private function cloneInputStream($inputStream)
 
         return $cloneStream;
     }
+
+    /**
+     * @param resource $inputStream
+     */
+    private function doReadInput($inputStream, ?string $exitChar = null, ?TerminalInputHelper $helper = null): string
+    {
+        $ret = '';
+        $helper ??= new TerminalInputHelper($inputStream, false);
+
+        while (!feof($inputStream)) {
+            $helper->waitForInput();
+            $char = fread($inputStream, 1);
+
+            // as opposed to fgets(), fread() returns an empty string when the stream content is empty, not false.
+            if (false === $char || ('' === $ret && '' === $char)) {
+                throw new MissingInputException('Aborted.');
+            }
+
+            if (\PHP_EOL === "{$ret}{$char}" || $exitChar === $char) {
+                break;
+            }
+
+            $ret .= $char;
+
+            if (null === $exitChar && "\n" === $char) {
+                break;
+            }
+        }
+
+        return $ret;
+    }
 }

Helper/TerminalInputHelper.php

@@ -37,51 +37,63 @@ final class TerminalInputHelper
     /** @var resource */
     private $inputStream;
     private bool $isStdin;
-    private string $initialState;
+    private string $initialState = '';
     private int $signalToKill = 0;
     private array $signalHandlers = [];
     private array $targetSignals = [];
+    private bool $withStty;
 
     /**
      * @param resource $inputStream
      *
      * @throws \RuntimeException If unable to read terminal settings
      */
-    public function __construct($inputStream)
+    public function __construct($inputStream, bool $withStty = true)
     {
-        if (!\is_string($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();
+        $this->withStty = $withStty;
+
+        if ($withStty) {
+            if (!\is_string($state = shell_exec('stty -g'))) {
+                throw new \RuntimeException('Unable to read the terminal settings.');
+            }
+
+            $this->initialState = $state;
+
+            $this->createSignalHandlers();
+        }
     }
 
     /**
-     * Waits for input and terminates if sent a default signal.
+     * Waits for input.
      */
     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
+            // Allow signal handlers to run
             while (0 === @stream_select($r, $w, $w, 0, 100)) {
                 $r = [$this->inputStream];
             }
         }
-        $this->checkForKillSignal();
+
+        if ($this->withStty) {
+            $this->checkForKillSignal();
+        }
     }
 
     /**
      * Restores terminal state and signal handlers.
      */
     public function finish(): void
     {
+        if (!$this->withStty) {
+            return;
+        }
+
         // Safeguard in case an unhandled kill signal exists
         $this->checkForKillSignal();
         shell_exec('stty '.$this->initialState);

Tests/Fixtures/application_test_sigint.php

@@ -0,0 +1,46 @@
+<?php
+
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Helper\QuestionHelper;
+use Symfony\Component\Console\Input\ArgvInput;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\ConsoleOutput;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Question\Question;
+
+$vendor = __DIR__;
+while (!file_exists($vendor.'/vendor')) {
+    $vendor = \dirname($vendor);
+}
+require $vendor.'/vendor/autoload.php';
+
+(new class extends Command {
+    protected function configure(): void
+    {
+        $this->addArgument('mode', InputArgument::OPTIONAL, default: 'single');
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $mode = $input->getArgument('mode');
+
+        $question = new Question('Enter text: ');
+        $question->setMultiline($mode !== 'single');
+
+        $helper = new QuestionHelper();
+
+        pcntl_async_signals(true);
+        pcntl_signal(\SIGALRM, function () {
+            posix_kill(posix_getpid(), \SIGINT);
+            pcntl_signal_dispatch();
+        });
+        pcntl_alarm(1);
+
+        $helper->ask($input, $output, $question);
+
+        return Command::SUCCESS;
+    }
+})
+    ->run(new ArgvInput($argv), new ConsoleOutput())
+;

Tests/Helper/QuestionHelperTest.php

@@ -26,6 +26,8 @@
 use Symfony\Component\Console\Question\Question;
 use Symfony\Component\Console\Terminal;
 use Symfony\Component\Console\Tester\ApplicationTester;
+use Symfony\Component\Process\Exception\ProcessSignaledException;
+use Symfony\Component\Process\Process;
 
 /**
  * @group tty
@@ -929,6 +931,28 @@ public function testAutocompleteMoveCursorBackwards()
         $this->assertStringEndsWith("\033[1D\033[K\033[2D\033[K\033[1D\033[K", stream_get_contents($stream));
     }
 
+    /**
+     * @testWith ["single"]
+     *           ["multi"]
+     */
+    public function testExitCommandOnInputSIGINT(string $mode)
+    {
+        if (!\function_exists('pcntl_signal')) {
+            $this->markTestSkipped('pcntl signals not available');
+        }
+
+        $p = new Process(
+            ['php', dirname(__DIR__).'/Fixtures/application_test_sigint.php', $mode],
+            timeout: 2, // the process will auto shutdown if not killed by SIGINT, to prevent blocking
+        );
+        $p->setPty(true);
+        $p->start();
+
+        $this->expectException(ProcessSignaledException::class);
+        $this->expectExceptionMessage('The process has been signaled with signal "2".');
+        $p->wait();
+    }
+
     protected function getInputStream($input)
     {
         $stream = fopen('php://memory', 'r+', false);