Capture signals and wait until child process exits to also exit, fixes #6059

src/Composer/Console/Application.php

@@ -17,6 +17,7 @@ use Composer\Util\Filesystem;
 use Composer\Util\Platform;
 use Composer\Util\Silencer;
 use LogicException;
+use Seld\Signal\SignalHandler;
 use Symfony\Component\Console\Application as BaseApplication;
 use Symfony\Component\Console\Exception\CommandNotFoundException;
 use Symfony\Component\Console\Helper\HelperSet;
@@ -93,7 +94,15 @@ class Application extends BaseApplication
             date_default_timezone_set(Silencer::call('date_default_timezone_get'));
         }
 
+        $this->io = new NullIO();
+
         if (!$shutdownRegistered) {
+            $signalHandler = SignalHandler::create([SignalHandler::SIGINT, SignalHandler::SIGTERM, SignalHandler::SIGHUP], function (string $signal, SignalHandler $handler) {
+                $this->io->writeError('Received '.$signal.', aborting', true, IOInterface::DEBUG);
+
+                $handler->exitWithLastSignal();
+            });
+
             $shutdownRegistered = true;
 
             register_shutdown_function(static function (): void {
@@ -107,8 +116,6 @@ class Application extends BaseApplication
             });
         }
 
-        $this->io = new NullIO();
-
         $this->initialWorkingDirectory = getcwd();
 
         parent::__construct('Composer', Composer::getVersion());

src/Composer/EventDispatcher/ScriptExecutionException.php

@@ -13,6 +13,8 @@
 namespace Composer\EventDispatcher;
 
 /**
+ * Thrown when a script running an external process exits with a non-0 status code
+ *
  * @author Jordi Boggiano <j.boggiano@seld.be>
  */
 class ScriptExecutionException extends \RuntimeException

src/Composer/Util/ProcessExecutor.php

@@ -14,6 +14,8 @@ namespace Composer\Util;
 
 use Composer\IO\IOInterface;
 use Composer\Pcre\Preg;
+use Seld\Signal\SignalHandler;
+use Symfony\Component\Process\Exception\ProcessSignaledException;
 use Symfony\Component\Process\Process;
 use Symfony\Component\Process\Exception\RuntimeException;
 use React\Promise\Promise;
@@ -125,6 +127,13 @@ class ProcessExecutor
             $this->outputHandler($type, $buffer);
         };
 
+        $signalHandler = SignalHandler::create([SignalHandler::SIGINT, SignalHandler::SIGTERM, SignalHandler::SIGHUP], function (string $signal) {
+            if ($this->io !== null) {
+                $this->io->writeError('Received '.$signal.', aborting when child process is done', true, IOInterface::DEBUG);
+            }
+        });
+
+        try {
             $process->run($callback);
 
             if ($this->captureOutput && !is_callable($output)) {
@@ -132,6 +141,14 @@ class ProcessExecutor
             }
 
             $this->errorOutput = $process->getErrorOutput();
+        } catch (ProcessSignaledException $e) {
+            if ($signalHandler->isTriggered()) {
+                // exiting as we were signaled and the child process exited too due to the signal
+                $signalHandler->exitWithLastSignal();
+            }
+        } finally {
+            $signalHandler->unregister();
+        }
 
         return $process->getExitCode();
     }