Fix add_signal_handler to raise the same exc asyncio raises for inv signal

Author: 1st1

tests/test_signals.py

@@ -262,6 +262,18 @@ def handler_hup():
 
         self.loop.run_until_complete(runner())
 
+    def test_signals_invalid_signal(self):
+        with self.assertRaisesRegex(RuntimeError,
+                                    'sig {} cannot be caught'.format(
+                                        signal.SIGKILL)):
+
+            self.loop.add_signal_handler(signal.SIGKILL, lambda *a: None)
+
+    def test_signals_coro_callback(self):
+        async def coro(): pass
+        with self.assertRaisesRegex(TypeError, 'coroutines cannot be used'):
+            self.loop.add_signal_handler(signal.SIGHUP, coro)
+
 
 class Test_UV_Signals(_TestSignal, tb.UVTestCase):
     NEW_LOOP = 'uvloop.new_event_loop()'

uvloop/includes/system.pxd

@@ -59,3 +59,4 @@ cdef extern from "errno.h" nogil:
         int ENOTSOCK
         int EBADF
         int ENOSYS
+        int EINVAL

uvloop/loop.pyx

@@ -1657,7 +1657,14 @@ cdef class Loop:
             # any signals installed by user
             return
 
-        uvs.start()
+        try:
+            uvs.start()
+        except OSError as exc:
+            del self._signal_handlers[sig]
+            if exc.errno == errno.EINVAL:
+                raise RuntimeError('sig {} cannot be caught'.format(sig))
+            else:
+                raise
 
     def remove_signal_handler(self, sig):
         cdef: