Fixes Issue #14635: telnetlib will use poll() rather than select() when possible

to avoid failing due to the select() file descriptor limit.

Contributed by Akintayo Holder and under the Google contributor agreement.

Lib/test/test_telnetlib.py

@@ -135,6 +135,28 @@ class ReadTests(TestCase):
         self.assertEqual(data, want[0])
         self.assertEqual(telnet.read_all(), 'not seen')
 
+    def test_read_until_with_poll(self):
+        """Use select.poll() to implement telnet.read_until()."""
+        want = ['x' * 10, 'match', 'y' * 10, EOF_sigil]
+        self.dataq.put(want)
+        telnet = telnetlib.Telnet(HOST, self.port)
+        if not telnet._has_poll:
+            raise unittest.SkipTest('select.poll() is required')
+        telnet._has_poll = True
+        self.dataq.join()
+        data = telnet.read_until('match')
+        self.assertEqual(data, ''.join(want[:-2]))
+
+    def test_read_until_with_select(self):
+        """Use select.select() to implement telnet.read_until()."""
+        want = ['x' * 10, 'match', 'y' * 10, EOF_sigil]
+        self.dataq.put(want)
+        telnet = telnetlib.Telnet(HOST, self.port)
+        telnet._has_poll = False
+        self.dataq.join()
+        data = telnet.read_until('match')
+        self.assertEqual(data, ''.join(want[:-2]))
+
     def test_read_all_A(self):
         """
         read_all()
@@ -357,8 +379,75 @@ class OptionTests(TestCase):
         self.assertEqual('', telnet.read_sb_data())
         nego.sb_getter = None # break the nego => telnet cycle
 
+
+class ExpectTests(TestCase):
+    def setUp(self):
+        self.evt = threading.Event()
+        self.dataq = Queue.Queue()
+        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.sock.settimeout(10)
+        self.port = test_support.bind_port(self.sock)
+        self.thread = threading.Thread(target=server, args=(self.evt,self.sock,
+                                                            self.dataq))
+        self.thread.start()
+        self.evt.wait()
+
+    def tearDown(self):
+        self.thread.join()
+
+    # use a similar approach to testing timeouts as test_timeout.py
+    # these will never pass 100% but make the fuzz big enough that it is rare
+    block_long = 0.6
+    block_short = 0.3
+    def test_expect_A(self):
+        """
+        expect(expected, [timeout])
+          Read until the expected string has been seen, or a timeout is
+          hit (default is no timeout); may block.
+        """
+        want = ['x' * 10, 'match', 'y' * 10, EOF_sigil]
+        self.dataq.put(want)
+        telnet = telnetlib.Telnet(HOST, self.port)
+        self.dataq.join()
+        (_,_,data) = telnet.expect(['match'])
+        self.assertEqual(data, ''.join(want[:-2]))
+
+    def test_expect_B(self):
+        # test the timeout - it does NOT raise socket.timeout
+        want = ['hello', self.block_long, 'not seen', EOF_sigil]
+        self.dataq.put(want)
+        telnet = telnetlib.Telnet(HOST, self.port)
+        self.dataq.join()
+        (_,_,data) = telnet.expect(['not seen'], self.block_short)
+        self.assertEqual(data, want[0])
+        self.assertEqual(telnet.read_all(), 'not seen')
+
+    def test_expect_with_poll(self):
+        """Use select.poll() to implement telnet.expect()."""
+        want = ['x' * 10, 'match', 'y' * 10, EOF_sigil]
+        self.dataq.put(want)
+        telnet = telnetlib.Telnet(HOST, self.port)
+        if not telnet._has_poll:
+            raise unittest.SkipTest('select.poll() is required')
+        telnet._has_poll = True
+        self.dataq.join()
+        (_,_,data) = telnet.expect(['match'])
+        self.assertEqual(data, ''.join(want[:-2]))
+
+    def test_expect_with_select(self):
+        """Use select.select() to implement telnet.expect()."""
+        want = ['x' * 10, 'match', 'y' * 10, EOF_sigil]
+        self.dataq.put(want)
+        telnet = telnetlib.Telnet(HOST, self.port)
+        telnet._has_poll = False
+        self.dataq.join()
+        (_,_,data) = telnet.expect(['match'])
+        self.assertEqual(data, ''.join(want[:-2]))
+
+
 def test_main(verbose=None):
-    test_support.run_unittest(GeneralTests, ReadTests, OptionTests)
+    test_support.run_unittest(GeneralTests, ReadTests, OptionTests,
+                              ExpectTests)
 
 if __name__ == '__main__':
     test_main()