1 files changed, 56 insertions, 10 deletions
diff --git a/Lib/test/test_poll.py b/Lib/test/test_poll.py
index f2d1795e9e..a07a7199c1 100644
--- a/Lib/test/test_poll.py
+++ b/Lib/test/test_poll.py
@@ -1,8 +1,15 @@
 # Test case for the os.poll() function
 
-import os, select, random, unittest
-import _testcapi
-from test.support import TESTFN, run_unittest
+import os
+import random
+import select
+try:
+    import threading
+except ImportError:
+    threading = None
+import time
+import unittest
+from test.support import TESTFN, run_unittest, reap_threads, cpython_only
 
 try:
     select.poll
@@ -151,14 +158,53 @@ class PollTests(unittest.TestCase):
         if x != 5:
             self.fail('Overflow must have occurred')
 
+        # Issues #15989, #17919
+        self.assertRaises(OverflowError, pollster.register, 0, -1)
+        self.assertRaises(OverflowError, pollster.register, 0, 1 << 64)
+        self.assertRaises(OverflowError, pollster.modify, 1, -1)
+        self.assertRaises(OverflowError, pollster.modify, 1, 1 << 64)
+
+    @cpython_only
+    def test_poll_c_limits(self):
+        from _testcapi import USHRT_MAX, INT_MAX, UINT_MAX
+        pollster = select.poll()
+        pollster.register(1)
+
+        # Issues #15989, #17919
+        self.assertRaises(OverflowError, pollster.register, 0, USHRT_MAX + 1)
+        self.assertRaises(OverflowError, pollster.modify, 1, USHRT_MAX + 1)
+        self.assertRaises(OverflowError, pollster.poll, INT_MAX + 1)
+        self.assertRaises(OverflowError, pollster.poll, UINT_MAX + 1)
+
+    @unittest.skipUnless(threading, 'Threading required for this test.')
+    @reap_threads
+    def test_threaded_poll(self):
+        r, w = os.pipe()
+        self.addCleanup(os.close, r)
+        self.addCleanup(os.close, w)
+        rfds = []
+        for i in range(10):
+            fd = os.dup(r)
+            self.addCleanup(os.close, fd)
+            rfds.append(fd)
         pollster = select.poll()
-        # Issue 15989
-        self.assertRaises(OverflowError, pollster.register, 0,
-                          _testcapi.SHRT_MAX + 1)
-        self.assertRaises(OverflowError, pollster.register, 0,
-                          _testcapi.USHRT_MAX + 1)
-        self.assertRaises(OverflowError, pollster.poll, _testcapi.INT_MAX + 1)
-        self.assertRaises(OverflowError, pollster.poll, _testcapi.UINT_MAX + 1)
+        for fd in rfds:
+            pollster.register(fd, select.POLLIN)
+
+        t = threading.Thread(target=pollster.poll)
+        t.start()
+        try:
+            time.sleep(0.5)
+            # trigger ufds array reallocation
+            for fd in rfds:
+                pollster.unregister(fd)
+            pollster.register(w, select.POLLOUT)
+            self.assertRaises(RuntimeError, pollster.poll)
+        finally:
+            # and make the call to poll() from the thread return
+            os.write(w, b'spam')
+            t.join()
+
 
 def test_main():
     run_unittest(PollTests)