properly clean up after using SIGALRM signal in tests

Author: boegel

test/framework/run.py

@@ -206,22 +206,25 @@ def test_run_cmd_negative_exit_code(self):
         def handler(signum, _):
             raise RuntimeError("Signal handler called with signal %s" % signum)
 
-        # set the signal handler and a 3-second alarm
-        signal.signal(signal.SIGALRM, handler)
-        signal.alarm(3)
+        try:
+            # set the signal handler and a 3-second alarm
+            signal.signal(signal.SIGALRM, handler)
+            signal.alarm(3)
 
-        (_, ec) = run_cmd("kill -9 $$", log_ok=False)
-        self.assertEqual(ec, -9)
+            (_, ec) = run_cmd("kill -9 $$", log_ok=False)
+            self.assertEqual(ec, -9)
 
-        # reset the alarm
-        signal.alarm(0)
-        signal.alarm(3)
+            # reset the alarm
+            signal.alarm(0)
+            signal.alarm(3)
 
-        (_, ec) = run_cmd_qa("kill -9 $$", {}, log_ok=False)
-        self.assertEqual(ec, -9)
+            (_, ec) = run_cmd_qa("kill -9 $$", {}, log_ok=False)
+            self.assertEqual(ec, -9)
 
-        # disable the alarm
-        signal.alarm(0)
+        finally:
+            # cleanup: disable the alarm + reset signal handler for SIGALRM
+            signal.signal(signal.SIGALRM, signal.SIG_DFL)
+            signal.alarm(0)
 
     def test_run_cmd_bis(self):
         """More 'complex' test for run_cmd function."""

test/framework/toy_build.py

@@ -2758,7 +2758,8 @@ def __enter__(self):
                 signal.alarm(self.seconds)
 
             def __exit__(self, type, value, traceback):
-                # cancel scheduled alarm (just for cleanup sake)
+                # clean up SIGALRM signal handler, and cancel scheduled alarm
+                signal.signal(signal.SIGALRM, signal.SIG_DFL)
                 signal.alarm(0)
 
         # wait for lock to be removed, with 1 second interval of checking;
@@ -2871,7 +2872,8 @@ def __enter__(self):
                 signal.alarm(self.seconds)
 
             def __exit__(self, type, value, traceback):
-                # cancel scheduled alarm (just for cleanup sake)
+                # clean up SIGALRM signal handler, and cancel scheduled alarm
+                signal.signal(signal.SIGALRM, signal.SIG_DFL)
                 signal.alarm(0)
 
         # add extra sleep command to ensure session takes long enough