[3.6] bpo-31786: Make functions in the select module blocking when timeout is a small negative value. (GH-4003). (#4022)

(cherry picked from commit 2c15b29aea5d6b9c61aa42d2c24a07ff1edb4b46)

2 files changed, 25 insertions, 0 deletions

diff --git a/Lib/test/test_poll.py b/Lib/test/test_poll.py
index 6a2bf6e..2a39360 100644
--- a/Lib/test/test_poll.py
+++ b/Lib/test/test_poll.py
@@ -208,6 +208,28 @@ class PollTests(unittest.TestCase):
             os.write(w, b'spam')
             t.join()
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
+    @reap_threads
+    def test_poll_blocks_with_negative_ms(self):
+        for timeout_ms in [None, -1, -1.0, -0.1, -1e-100]:
+            # Create two file descriptors. This will be used to unlock
+            # the blocking call to poll.poll inside the thread
+            r, w = os.pipe()
+            pollster = select.poll()
+            pollster.register(r, select.POLLIN)
+
+            poll_thread = threading.Thread(target=pollster.poll, args=(timeout_ms,))
+            poll_thread.start()
+            poll_thread.join(timeout=0.1)
+            self.assertTrue(poll_thread.is_alive())
+
+            # Write to the pipe so pollster.poll unblocks and the thread ends.
+            os.write(w, b'spam')
+            poll_thread.join()
+            self.assertFalse(poll_thread.is_alive())
+            os.close(r)
+            os.close(w)
+
 
 def test_main():
     run_unittest(PollTests)
diff --git a/Lib/test/test_time.py b/Lib/test/test_time.py
index 7093fc6..5b6e58f 100644
--- a/Lib/test/test_time.py
+++ b/Lib/test/test_time.py
@@ -36,6 +36,8 @@ class _PyTime(enum.IntEnum):
     ROUND_CEILING = 1
     # Round to nearest with ties going to nearest even integer
     ROUND_HALF_EVEN = 2
+    # Round away from zero
+    ROUND_UP = 3
 
 # Rounding modes supported by PyTime
 ROUNDING_MODES = (
@@ -43,6 +45,7 @@ ROUNDING_MODES = (
     (_PyTime.ROUND_FLOOR, decimal.ROUND_FLOOR),
     (_PyTime.ROUND_CEILING, decimal.ROUND_CEILING),
     (_PyTime.ROUND_HALF_EVEN, decimal.ROUND_HALF_EVEN),
+    (_PyTime.ROUND_UP, decimal.ROUND_UP),
 )