Issue #22018: Add _testcapi.raise_signal()

- Use _testcapi.raise_signal() in test_signal
- close also os.pipe() file descriptors in some test_signal tests where they
  were not closed properly
- Remove faulthandler._sigill() and faulthandler._sigbus(): reuse
  _testcapi.raise_signal() in test_faulthandler

Lib/test/test_signal.py

@@ -15,6 +15,10 @@ try:
     import threading
 except ImportError:
     threading = None
+try:
+    import _testcapi
+except ImportError:
+    _testcapi = None
 
 
 class HandlerBCalled(Exception):
@@ -250,12 +254,27 @@ class WakeupFDTests(unittest.TestCase):
         fd = support.make_bad_fd()
         self.assertRaises(ValueError, signal.set_wakeup_fd, fd)
 
+    def test_set_wakeup_fd_result(self):
+        r1, w1 = os.pipe()
+        os.close(r1)
+        self.addCleanup(os.close, w1)
+        r2, w2 = os.pipe()
+        os.close(r2)
+        self.addCleanup(os.close, w2)
+
+        signal.set_wakeup_fd(w1)
+        self.assertIs(signal.set_wakeup_fd(w2), w1)
+        self.assertIs(signal.set_wakeup_fd(-1), w2)
+        self.assertIs(signal.set_wakeup_fd(-1), -1)
+
 
 @unittest.skipIf(sys.platform == "win32", "Not valid on Windows")
 class WakeupSignalTests(unittest.TestCase):
+    @unittest.skipIf(_testcapi is None, 'need _testcapi')
     def check_wakeup(self, test_body, *signals, ordered=True):
         # use a subprocess to have only one thread
         code = """if 1:
+        import _testcapi
         import fcntl
         import os
         import signal
@@ -294,17 +313,18 @@ class WakeupSignalTests(unittest.TestCase):
 
         assert_python_ok('-c', code)
 
+    @unittest.skipIf(_testcapi is None, 'need _testcapi')
     def test_wakeup_write_error(self):
         # Issue #16105: write() errors in the C signal handler should not
         # pass silently.
         # Use a subprocess to have only one thread.
         code = """if 1:
+        import _testcapi
         import errno
         import fcntl
         import os
         import signal
         import sys
-        import time
         from test.support import captured_stderr
 
         def handler(signum, frame):
@@ -319,8 +339,7 @@ class WakeupSignalTests(unittest.TestCase):
         signal.set_wakeup_fd(r)
         try:
             with captured_stderr() as err:
-                signal.alarm(1)
-                time.sleep(5.0)
+                _testcapi.raise_signal(signal.SIGALRM)
         except ZeroDivisionError:
             # An ignored exception should have been printed out on stderr
             err = err.getvalue()
@@ -331,6 +350,9 @@ class WakeupSignalTests(unittest.TestCase):
                 raise AssertionError(err)
         else:
             raise AssertionError("ZeroDivisionError not raised")
+
+        os.close(r)
+        os.close(w)
         """
         r, w = os.pipe()
         try:
@@ -394,9 +416,10 @@ class WakeupSignalTests(unittest.TestCase):
 
     def test_signum(self):
         self.check_wakeup("""def test():
+            import _testcapi
             signal.signal(signal.SIGUSR1, handler)
-            os.kill(os.getpid(), signal.SIGUSR1)
-            os.kill(os.getpid(), signal.SIGALRM)
+            _testcapi.raise_signal(signal.SIGUSR1)
+            _testcapi.raise_signal(signal.SIGALRM)
         """, signal.SIGUSR1, signal.SIGALRM)
 
     @unittest.skipUnless(hasattr(signal, 'pthread_sigmask'),
@@ -410,8 +433,8 @@ class WakeupSignalTests(unittest.TestCase):
             signal.signal(signum2, handler)
 
             signal.pthread_sigmask(signal.SIG_BLOCK, (signum1, signum2))
-            os.kill(os.getpid(), signum1)
-            os.kill(os.getpid(), signum2)
+            _testcapi.raise_signal(signum1)
+            _testcapi.raise_signal(signum2)
             # Unblocking the 2 signals calls the C signal handler twice
             signal.pthread_sigmask(signal.SIG_UNBLOCK, (signum1, signum2))
         """,  signal.SIGUSR1, signal.SIGUSR2, ordered=False)
@@ -447,18 +470,22 @@ class SiginterruptTest(unittest.TestCase):
             sys.stdout.flush()
 
             # run the test twice
-            for loop in range(2):
-                # send a SIGALRM in a second (during the read)
-                signal.alarm(1)
-                try:
-                    # blocking call: read from a pipe without data
-                    os.read(r, 1)
-                except OSError as err:
-                    if err.errno != errno.EINTR:
-                        raise
-                else:
-                    sys.exit(2)
-            sys.exit(3)
+            try:
+                for loop in range(2):
+                    # send a SIGALRM in a second (during the read)
+                    signal.alarm(1)
+                    try:
+                        # blocking call: read from a pipe without data
+                        os.read(r, 1)
+                    except OSError as err:
+                        if err.errno != errno.EINTR:
+                            raise
+                    else:
+                        sys.exit(2)
+                sys.exit(3)
+            finally:
+                os.close(r)
+                os.close(w)
         """ % (interrupt,)
         with spawn_python('-c', code) as process:
             try: