Python signal.getsignal() Examples

def __call__(self, *args, **kwargs):
        """Trap ``SIGTERM`` and call wrapped function."""
        self._caught_signal = None
        # Register handler for SIGTERM, then call `self.func`
        self.old_signal_handler = signal.getsignal(signal.SIGTERM)
        signal.signal(signal.SIGTERM, self.signal_handler)

        self.func(*args, **kwargs)

        # Restore old signal handler
        signal.signal(signal.SIGTERM, self.old_signal_handler)

        # Handle any signal caught during execution
        if self._caught_signal is not None:
            signum, frame = self._caught_signal
            if callable(self.old_signal_handler):
                self.old_signal_handler(signum, frame)
            elif self.old_signal_handler == signal.SIG_DFL:
                sys.exit(0) 

def testTwoResults(self):
        unittest.installHandler()

        result = unittest.TestResult()
        unittest.registerResult(result)
        new_handler = signal.getsignal(signal.SIGINT)

        result2 = unittest.TestResult()
        unittest.registerResult(result2)
        self.assertEqual(signal.getsignal(signal.SIGINT), new_handler)

        result3 = unittest.TestResult()

        def test(result):
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)

        try:
            test(result)
        except KeyboardInterrupt:
            self.fail("KeyboardInterrupt not handled")

        self.assertTrue(result.shouldStop)
        self.assertTrue(result2.shouldStop)
        self.assertFalse(result3.shouldStop) 

def testHandlerReplacedButCalled(self):
        # If our handler has been replaced (is no longer installed) but is
        # called by the *new* handler, then it isn't safe to delay the
        # SIGINT and we should immediately delegate to the default handler
        unittest.installHandler()

        handler = signal.getsignal(signal.SIGINT)
        def new_handler(frame, signum):
            handler(frame, signum)
        signal.signal(signal.SIGINT, new_handler)

        try:
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)
        except KeyboardInterrupt:
            pass
        else:
            self.fail("replaced but delegated handler doesn't raise interrupt") 

def testHandlerReplacedButCalled(self):
        # Can't use skipIf decorator because the signal handler may have
        # been changed after defining this method.
        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
            self.skipTest("test requires SIGINT to not be ignored")
        # If our handler has been replaced (is no longer installed) but is
        # called by the *new* handler, then it isn't safe to delay the
        # SIGINT and we should immediately delegate to the default handler
        unittest.installHandler()

        handler = signal.getsignal(signal.SIGINT)
        def new_handler(frame, signum):
            handler(frame, signum)
        signal.signal(signal.SIGINT, new_handler)

        try:
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)
        except KeyboardInterrupt:
            pass
        else:
            self.fail("replaced but delegated handler doesn't raise interrupt") 

def MakeValidSysOuts():
	if not isinstance(sys.stdout, SafeOutput):
		sys.stdout = sys.stderr = SafeOutput()
		# and for the sake of working around something I can't understand...
		# prevent keyboard interrupts from killing IIS
		import signal
		def noOp(a,b):
			# it would be nice to get to the bottom of this, so a warning to
			# the debug console can't hurt.
			print "WARNING: Ignoring keyboard interrupt from ActiveScripting engine"
		# If someone else has already redirected, then assume they know what they are doing!
		if signal.getsignal(signal.SIGINT) == signal.default_int_handler:
			try:
				signal.signal(signal.SIGINT, noOp)
			except ValueError:
				# Not the main thread - can't do much.
				pass 

def testTwoResults(self):
        unittest.installHandler()

        result = unittest.TestResult()
        unittest.registerResult(result)
        new_handler = signal.getsignal(signal.SIGINT)

        result2 = unittest.TestResult()
        unittest.registerResult(result2)
        self.assertEqual(signal.getsignal(signal.SIGINT), new_handler)

        result3 = unittest.TestResult()

        def test(result):
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)

        try:
            test(result)
        except KeyboardInterrupt:
            self.fail("KeyboardInterrupt not handled")

        self.assertTrue(result.shouldStop)
        self.assertTrue(result2.shouldStop)
        self.assertFalse(result3.shouldStop) 

def test_signal_signal(self):
        WORKING_CASES = SUPPORTED_SIGNALS + [6]
        WEIRD_CASES = {
                    6: None,
                    2: signal.default_int_handler}
        for x in WORKING_CASES:
            #Ideal handler signature
            def a(signum, frame):
                return x
            
            ret_val = signal.signal(x, a)
            if x not in WEIRD_CASES.keys():
                self.assertEqual(ret_val, signal.SIG_DFL)
            else:
                self.assertEqual(ret_val, WEIRD_CASES[x])
            self.assertEqual(a, signal.getsignal(x))
            
        #Strange handler signatures
        class KNew(object):
            def __call__(self, *args, **kwargs):
                pass
        
        a = KNew()
        ret_val = signal.signal(signal.SIGBREAK, a)
        self.assertEqual(a, signal.getsignal(signal.SIGBREAK)) 

def testSecondInterrupt(self):
        # Can't use skipIf decorator because the signal handler may have
        # been changed after defining this method.
        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
            self.skipTest("test requires SIGINT to not be ignored")
        result = unittest.TestResult()
        unittest.installHandler()
        unittest.registerResult(result)

        def test(result):
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)
            result.breakCaught = True
            self.assertTrue(result.shouldStop)
            os.kill(pid, signal.SIGINT)
            self.fail("Second KeyboardInterrupt not raised")

        try:
            test(result)
        except KeyboardInterrupt:
            pass
        else:
            self.fail("Second KeyboardInterrupt not raised")
        self.assertTrue(result.breakCaught) 

def testSecondInterrupt(self):
        # Can't use skipIf decorator because the signal handler may have
        # been changed after defining this method.
        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
            self.skipTest("test requires SIGINT to not be ignored")
        result = unittest.TestResult()
        unittest.installHandler()
        unittest.registerResult(result)

        def test(result):
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)
            result.breakCaught = True
            self.assertTrue(result.shouldStop)
            os.kill(pid, signal.SIGINT)
            self.fail("Second KeyboardInterrupt not raised")

        try:
            test(result)
        except KeyboardInterrupt:
            pass
        else:
            self.fail("Second KeyboardInterrupt not raised")
        self.assertTrue(result.breakCaught) 

def testHandlerReplacedButCalled(self):
        # Can't use skipIf decorator because the signal handler may have
        # been changed after defining this method.
        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
            self.skipTest("test requires SIGINT to not be ignored")
        # If our handler has been replaced (is no longer installed) but is
        # called by the *new* handler, then it isn't safe to delay the
        # SIGINT and we should immediately delegate to the default handler
        unittest.installHandler()

        handler = signal.getsignal(signal.SIGINT)
        def new_handler(frame, signum):
            handler(frame, signum)
        signal.signal(signal.SIGINT, new_handler)

        try:
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)
        except KeyboardInterrupt:
            pass
        else:
            self.fail("replaced but delegated handler doesn't raise interrupt") 

def __call__(self, *args, **kwargs):
        """Trap ``SIGTERM`` and call wrapped function."""
        self._caught_signal = None
        # Register handler for SIGTERM, then call `self.func`
        self.old_signal_handler = signal.getsignal(signal.SIGTERM)
        signal.signal(signal.SIGTERM, self.signal_handler)

        self.func(*args, **kwargs)

        # Restore old signal handler
        signal.signal(signal.SIGTERM, self.old_signal_handler)

        # Handle any signal caught during execution
        if self._caught_signal is not None:
            signum, frame = self._caught_signal
            if callable(self.old_signal_handler):
                self.old_signal_handler(signum, frame)
            elif self.old_signal_handler == signal.SIG_DFL:
                sys.exit(0) 

def testTwoResults(self):
        unittest.installHandler()

        result = unittest.TestResult()
        unittest.registerResult(result)
        new_handler = signal.getsignal(signal.SIGINT)

        result2 = unittest.TestResult()
        unittest.registerResult(result2)
        self.assertEqual(signal.getsignal(signal.SIGINT), new_handler)

        result3 = unittest.TestResult()

        def test(result):
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)

        try:
            test(result)
        except KeyboardInterrupt:
            self.fail("KeyboardInterrupt not handled")

        self.assertTrue(result.shouldStop)
        self.assertTrue(result2.shouldStop)
        self.assertFalse(result3.shouldStop) 

def __call__(self, *args, **kwargs):
        self._caught_signal = None
        # Register handler for SIGTERM, then call `self.func`
        self.old_signal_handler = signal.getsignal(signal.SIGTERM)
        signal.signal(signal.SIGTERM, self.signal_handler)

        self.func(*args, **kwargs)

        # Restore old signal handler
        signal.signal(signal.SIGTERM, self.old_signal_handler)

        # Handle any signal caught during execution
        if self._caught_signal is not None:
            signum, frame = self._caught_signal
            if callable(self.old_signal_handler):
                self.old_signal_handler(signum, frame)
            elif self.old_signal_handler == signal.SIG_DFL:
                sys.exit(0) 

def testTwoResults(self):
        unittest.installHandler()

        result = unittest.TestResult()
        unittest.registerResult(result)
        new_handler = signal.getsignal(signal.SIGINT)

        result2 = unittest.TestResult()
        unittest.registerResult(result2)
        self.assertEqual(signal.getsignal(signal.SIGINT), new_handler)

        result3 = unittest.TestResult()

        def test(result):
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)

        try:
            test(result)
        except KeyboardInterrupt:
            self.fail("KeyboardInterrupt not handled")

        self.assertTrue(result.shouldStop)
        self.assertTrue(result2.shouldStop)
        self.assertFalse(result3.shouldStop) 

def testHandlerReplacedButCalled(self):
        # Can't use skipIf decorator because the signal handler may have
        # been changed after defining this method.
        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
            self.skipTest("test requires SIGINT to not be ignored")
        # If our handler has been replaced (is no longer installed) but is
        # called by the *new* handler, then it isn't safe to delay the
        # SIGINT and we should immediately delegate to the default handler
        unittest.installHandler()

        handler = signal.getsignal(signal.SIGINT)
        def new_handler(frame, signum):
            handler(frame, signum)
        signal.signal(signal.SIGINT, new_handler)

        try:
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)
        except KeyboardInterrupt:
            pass
        else:
            self.fail("replaced but delegated handler doesn't raise interrupt") 

def test_signal(self):
        """
        Check that signals are restored after using _CursesScreen
        """
        if sys.platform == "win32":
            self.skipTest("Windows does not have signals.")

        def dummy_signal_handler():
            """Dummy previous signal handler."""
            pass
        outer_state = _SignalState()
        self.assertNotEqual(signal.getsignal(signal.SIGWINCH), dummy_signal_handler)
        outer_state.set(signal.SIGWINCH, dummy_signal_handler)
        self.assertEqual(signal.getsignal(signal.SIGWINCH), dummy_signal_handler)
        Screen.wrapper(self.signal_check)
        self.assertEqual(signal.getsignal(signal.SIGWINCH), dummy_signal_handler)
        outer_state.restore()
        self.assertNotEqual(signal.getsignal(signal.SIGWINCH), dummy_signal_handler) 

def test_save_signal_state(self):
        """Tests that the signal state class works properly.

        The _SignalState class must set, save, and restore signals
        when needed.
        """
        if sys.platform == "win32":
            self.skipTest("Windows does not have signals.")

        def dummy_handler():
            """Assign dummy handler to an arbitrary signal."""
            pass
        self.assertNotEqual(signal.getsignal(signal.SIGWINCH), dummy_handler)
        signal_state = _SignalState()
        signal_state.set(signal.SIGWINCH, dummy_handler)
        self.assertEqual(signal.getsignal(signal.SIGWINCH), dummy_handler)
        signal_state.restore()
        self.assertNotEqual(signal.getsignal(signal.SIGWINCH), dummy_handler) 

def _set_SIGCHLD_handler():
    # Windows doesn't support SIGCHLD handler
    if sys.platform == 'win32':
        return
    # can't set signal in child threads
    if not isinstance(threading.current_thread(), threading._MainThread):
        return
    global _SIGCHLD_handler_set
    if _SIGCHLD_handler_set:
        return
    previous_handler = signal.getsignal(signal.SIGCHLD)
    if not callable(previous_handler):
        previous_handler = None

    def handler(signum, frame):
        # This following call uses `waitid` with WNOHANG from C side. Therefore,
        # Python can still get and update the process status successfully.
        _error_if_any_worker_fails()
        if previous_handler is not None:
            previous_handler(signum, frame)

    signal.signal(signal.SIGCHLD, handler)
    _SIGCHLD_handler_set = True 

def __call__(self, *args, **kwargs):
        """Trap ``SIGTERM`` and call wrapped function."""
        self._caught_signal = None
        # Register handler for SIGTERM, then call `self.func`
        self.old_signal_handler = signal.getsignal(signal.SIGTERM)
        signal.signal(signal.SIGTERM, self.signal_handler)

        self.func(*args, **kwargs)

        # Restore old signal handler
        signal.signal(signal.SIGTERM, self.old_signal_handler)

        # Handle any signal caught during execution
        if self._caught_signal is not None:
            signum, frame = self._caught_signal
            if callable(self.old_signal_handler):
                self.old_signal_handler(signum, frame)
            elif self.old_signal_handler == signal.SIG_DFL:
                sys.exit(0) 

def testSecondInterrupt(self):
        # Can't use skipIf decorator because the signal handler may have
        # been changed after defining this method.
        if signal.getsignal(signal.SIGINT) == signal.SIG_IGN:
            self.skipTest("test requires SIGINT to not be ignored")
        result = unittest.TestResult()
        unittest.installHandler()
        unittest.registerResult(result)

        def test(result):
            pid = os.getpid()
            os.kill(pid, signal.SIGINT)
            result.breakCaught = True
            self.assertTrue(result.shouldStop)
            os.kill(pid, signal.SIGINT)
            self.fail("Second KeyboardInterrupt not raised")

        try:
            test(result)
        except KeyboardInterrupt:
            pass
        else:
            self.fail("Second KeyboardInterrupt not raised")
        self.assertTrue(result.breakCaught) 

def _set_SIGCHLD_handler():
    # Windows doesn't support SIGCHLD handler
    if sys.platform == 'win32':
        return
    # can't set signal in child threads
    if not isinstance(threading.current_thread(), threading._MainThread):
        return
    global _SIGCHLD_handler_set
    if _SIGCHLD_handler_set:
        return
    previous_handler = signal.getsignal(signal.SIGCHLD)
    if not callable(previous_handler):
        previous_handler = None

    def handler(signum, frame):
        # This following call uses `waitid` with WNOHANG from C side. Therefore,
        # Python can still get and update the process status successfully.
        _error_if_any_worker_fails()
        if previous_handler is not None:
            previous_handler(signum, frame)

    signal.signal(signal.SIGCHLD, handler)
    _SIGCHLD_handler_set = True 

def __enter__(self):
        self.interrupted = False
        self.released = False
        self.original_handler = signal.getsignal(self.sig)

        def handler(signum, frame):
            self.release()
            self.interrupted = True

        try:
            signal.signal(self.sig, handler)
        except ValueError:
            # when testing we can't use signal, just ignore
            pass

        return self 

def save_signal_handlers():
    saved = {}
    for sig in [signal.SIGINT, signal.SIGTERM, signal.SIGCHLD]:
        saved[sig] = signal.getsignal(sig)
    if "twisted" in repr(saved):
        # This indicates we're not cleaning up after ourselves properly.
        raise Exception("twisted signal handlers already installed")
    return saved 

def test_signal_getsignal_negative(self):
        for x in [-2, -1, 0, 23, 24, 25]:
            self.assertRaisesMessage(ValueError, "signal number out of range",
                                signal.getsignal, x)
        for x in [None, "abc", "14"]:
            self.assertRaises(TypeError, signal.getsignal, x) 

def ignore_sigint():
    handler = signal.getsignal(signal.SIGINT)
    signal.signal(signal.SIGINT, signal.SIG_IGN)
    try:
        yield
    finally:
        signal.signal(signal.SIGINT, handler) 

def setUp(self):
        self._default_handler = signal.getsignal(signal.SIGINT)
        if self.int_handler is not None:
            signal.signal(signal.SIGINT, self.int_handler) 

def installHandler():
    global _interrupt_handler
    if _interrupt_handler is None:
        default_handler = signal.getsignal(signal.SIGINT)
        _interrupt_handler = _InterruptHandler(default_handler)
        signal.signal(signal.SIGINT, _interrupt_handler) 

def __call__(self, signum, frame):
        installed_handler = signal.getsignal(signal.SIGINT)
        if installed_handler is not self:
            # if we aren't the installed handler, then delegate immediately
            # to the default handler
            self.default_handler(signum, frame)

        if self.called:
            self.default_handler(signum, frame)
        self.called = True
        for result in _results.keys():
            result.stop() 

def removeHandler(method=None):
    if method is not None:
        @wraps(method)
        def inner(*args, **kwargs):
            initial = signal.getsignal(signal.SIGINT)
            removeHandler()
            try:
                return method(*args, **kwargs)
            finally:
                signal.signal(signal.SIGINT, initial)
        return inner

    global _interrupt_handler
    if _interrupt_handler is not None:
        signal.signal(signal.SIGINT, _interrupt_handler.original_handler) 

def __enter__(self):

        self.interrupted = False
        self.released = False

        self.original_handler = signal.getsignal(self.sig)

        def handler(signum, frame):
            self.release()
            self.interrupted = True
            print("(Caught interrupt. Terminating when safe.... Press Ctrl-C again to force stop)")

        signal.signal(self.sig, handler)

        return self