Feat: signal handling via pcntl (fixes #12)

src/CLI.php

@@ -361,6 +361,52 @@ public static function spinner(int $frame = 0, bool $finalize = false) : void
         static::liveLine($frames[$frame % \count($frames)]);
     }
 
+    /**
+     * Register a handler for the given POSIX signal when pcntl is available.
+     *
+     * @param int $signal The signal number
+     * @param callable $handler The signal handler
+     *
+     * @return bool True if the handler was registered, false if pcntl is unavailable
+     */
+    public static function onSignal(int $signal, callable $handler) : bool
+    {
+        if (!\function_exists('pcntl_signal')) {
+            return false;
+        }
+        return \pcntl_signal($signal, $handler, true);
+    }
+
+    /**
+     * Register a cleanup handler for the interrupt signal (Ctrl+C) when available.
+     *
+     * @param callable $handler The signal handler
+     *
+     * @return bool True if the handler was registered
+     */
+    public static function onSigint(callable $handler) : bool
+    {
+        if (!\defined('SIGINT')) {
+            return false;
+        }
+        return static::onSignal(\SIGINT, $handler);
+    }
+
+    /**
+     * Restore the default handler for a POSIX signal when pcntl is available.
+     *
+     * @param int $signal The signal number
+     *
+     * @return bool True if the handler was restored
+     */
+    public static function restoreSignal(int $signal) : bool
+    {
+        if (!\function_exists('pcntl_signal')) {
+            return false;
+        }
+        return \pcntl_signal($signal, \SIG_DFL);
+    }
+
     /**
      * Performs audible beep alarms.
      *

tests/CLITest.php

@@ -266,4 +266,14 @@ public function testSpinner() : void
         self::assertStringContainsString('|', Stdout::getContents());
         CLI::setAnsi(true);
     }
+
+    public function testSignals() : void
+    {
+        $term = \defined('SIGTERM') ? \SIGTERM : 15;
+        self::assertIsBool(CLI::onSignal($term, static function () : void {
+        }));
+        self::assertIsBool(CLI::onSigint(static function () : void {
+        }));
+        self::assertIsBool(CLI::restoreSignal($term));
+    }
 }