signals: Use 'sigaction' syscall for setting up signal handlers

tests/test_signals.py

@@ -227,6 +227,85 @@ def handler_hup():
 class Test_UV_Signals(_TestSignal, tb.UVTestCase):
     NEW_LOOP = 'uvloop.new_event_loop()'
 
+    def test_signals_restore(self):
+        # Test that uvloop restores signals installed with the signals
+        # module after the loop is done running.
+
+        async def runner():
+            PROG = R"""\
+import asyncio
+import uvloop
+import signal
+import time
+
+srv = None
+
+async def worker():
+    global srv
+    cb = lambda *args: None
+    srv = await asyncio.start_server(cb, '127.0.0.1', 0)
+    print('READY', flush=True)
+
+def py_handler(signum, frame):
+    print('pyhandler', flush=True)
+
+def aio_handler():
+    print('aiohandler', flush=True)
+    loop.stop()
+
+signal.signal(signal.SIGUSR1, py_handler)
+
+print('step1', flush=True)
+print(input(), flush=True)
+loop = """ + self.NEW_LOOP + """
+loop.add_signal_handler(signal.SIGUSR1, aio_handler)
+asyncio.set_event_loop(loop)
+loop.create_task(worker())
+loop.run_forever()
+print('step3', flush=True)
+print(input(), flush=True)
+"""
+
+            proc = await asyncio.create_subprocess_exec(
+                sys.executable, b'-c', PROG,
+                stdin=subprocess.PIPE,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.PIPE,
+                loop=self.loop)
+
+            ln = await proc.stdout.readline()
+            self.assertEqual(ln, b'step1\n')
+
+            proc.send_signal(signal.SIGUSR1)
+            ln = await proc.stdout.readline()
+            self.assertEqual(ln, b'pyhandler\n')
+
+            proc.stdin.write(b'test\n')
+            ln = await proc.stdout.readline()
+            self.assertEqual(ln, b'test\n')
+
+            ln = await proc.stdout.readline()
+            self.assertEqual(ln, b'READY\n')
+
+            proc.send_signal(signal.SIGUSR1)
+            ln = await proc.stdout.readline()
+            self.assertEqual(ln, b'aiohandler\n')
+
+            ln = await proc.stdout.readline()
+            self.assertEqual(ln, b'step3\n')
+
+            proc.send_signal(signal.SIGUSR1)
+            ln = await proc.stdout.readline()
+            self.assertEqual(ln, b'pyhandler\n')
+
+            proc.stdin.write(b'done\n')
+
+            out, err = await proc.communicate()
+            self.assertEqual(out, b'done\n')
+            self.assertEqual(err, b'')
+
+        self.loop.run_until_complete(runner())
+
 
 class Test_AIO_Signals(_TestSignal, tb.AIOTestCase):
     NEW_LOOP = 'asyncio.new_event_loop()'

uvloop/os_signal.pyx

@@ -1,5 +1,5 @@
-from posix.signal cimport sigaction_t, sigaction
-from libc.signal cimport SIG_DFL, SIG_IGN, SIG_ERR, sighandler_t, signal, SIGINT
+from posix.signal cimport sigaction_t, sigaction, sigfillset
+from libc.signal cimport SIG_DFL, SIG_IGN, sighandler_t, signal, SIGINT
 
 
 cdef class SignalsStack:
@@ -22,16 +22,22 @@ cdef class SignalsStack:
     cdef restore(self):
         cdef:
             sighandler_t sig
+            sigaction_t sa
 
         if not self.saved:
             raise RuntimeError("SignalsStack.save() wasn't called")
 
         for i in range(MAX_SIG):
             if self.signals[i] == NULL:
                 continue
-            sig = signal(i, self.signals[i])
-            if sig == SIG_ERR:
-                raise RuntimeError("Couldn't restore signal {}".format(i))
+
+            memset(&sa, 0, sizeof(sa))
+            if sigfillset(&sa.sa_mask):
+                raise RuntimeError(
+                    'failed to restore signal (sigfillset failed)')
+            sa.sa_handler = self.signals[i]
+            if sigaction(i, &sa, NULL):
+                raise convert_error(-errno.errno)
 
 
 cdef void __signal_handler_sigint(int sig) nogil:
@@ -41,11 +47,7 @@ cdef void __signal_handler_sigint(int sig) nogil:
     # Python code here -- all '.' and '[]' operators work on
     # C structs/pointers.
 
-    if sig != SIGINT:
-        return
-
-    if __main_loop__ is None or __main_loop__.py_signals is None:
-        # Shouldn't ever happen.
+    if sig != SIGINT or __main_loop__ is None:
         return
 
     if __main_loop__._executing_py_code and not __main_loop__._custom_sigint:
@@ -54,9 +56,16 @@ cdef void __signal_handler_sigint(int sig) nogil:
 
     if __main_loop__.uv_signals is not None:
         handle = __main_loop__.uv_signals.signals[sig]
-        if handle not in (SIG_DFL, SIG_IGN, SIG_ERR, NULL):
+        if handle is not NULL:
             handle(sig)  # void
 
 
-cdef void __signal_set_sigint():
-    signal(SIGINT, <sighandler_t>__signal_handler_sigint)
+cdef __signal_set_sigint():
+    cdef sigaction_t sa
+    memset(&sa, 0, sizeof(sa))
+    if sigfillset(&sa.sa_mask):
+        raise RuntimeError(
+            'failed to set SIGINT signal (sigfillset failed)')
+    sa.sa_handler = __signal_handler_sigint
+    if sigaction(SIGINT, &sa, NULL):
+        raise convert_error(-errno.errno)