From 19b708e14102e9540fd8ad4e3beeeeb898ddf146 Mon Sep 17 00:00:00 2001
From: David Wilson <dw@botanicus.net>
Date: Wed, 23 Jan 2019 12:44:08 +0000
Subject: [PATCH] issue #415, #477: Poller must handle POLLHUP too.

Linux will fire poll() with simply the POLLHUP bit set even though it
was not requested, resulting in an infinite loop.
---
 mitogen/core.py      |  8 +++++---
 tests/poller_test.py | 44 ++++++++++++++++++++++++++++++++++++++------
 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/mitogen/core.py b/mitogen/core.py
index b5f6a372..a7ff05b2 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -1900,8 +1900,10 @@ class Poller(object):
         """
         pass
 
+    _readmask = select.POLLIN | select.POLLHUP
+
     def _update(self, fd):
-        mask = (((fd in self._rfds) and select.POLLIN) |
+        mask = (((fd in self._rfds) and self._readmask) |
                 ((fd in self._wfds) and select.POLLOUT))
         if mask:
             self._pollobj.register(fd, mask)
@@ -1951,8 +1953,8 @@ class Poller(object):
 
         events, _ = io_op(self._pollobj.poll, timeout)
         for fd, event in events:
-            if event & select.POLLIN:
-                _vv and IOLOG.debug('%r: POLLIN for %r', self, fd)
+            if event & self._readmask:
+                _vv and IOLOG.debug('%r: POLLIN|POLLHUP for %r', self, fd)
                 data, gen = self._rfds.get(fd, (None, None))
                 if gen and gen < self._generation:
                     yield data
diff --git a/tests/poller_test.py b/tests/poller_test.py
index c214f367..1d1e0cd0 100644
--- a/tests/poller_test.py
+++ b/tests/poller_test.py
@@ -13,6 +13,12 @@ import mitogen.parent
 
 import testlib
 
+try:
+    next
+except NameError:
+    # Python 2.4
+    from mitogen.core import next
+
 
 class SockMixin(object):
     def tearDown(self):
@@ -345,6 +351,22 @@ class FileClosedMixin(PollerMixin, SockMixin):
             pass
 
 
+class TtyHangupMixin(PollerMixin):
+    def test_tty_hangup_detected(self):
+        # bug in initial select.poll() implementation failed to detect POLLHUP.
+        master_fd, slave_fd = mitogen.parent.openpty()
+        try:
+            self.p.start_receive(master_fd)
+            self.assertEquals([], list(self.p.poll(0)))
+            os.close(slave_fd)
+            slave_fd = None
+            self.assertEquals([master_fd], list(self.p.poll(0)))
+        finally:
+            if slave_fd is not None:
+                os.close(slave_fd)
+            os.close(master_fd)
+
+
 class DistinctDataMixin(PollerMixin, SockMixin):
     # Verify different data is yielded for the same FD according to the event
     # being raised.
@@ -368,29 +390,39 @@ class AllMixin(ReceiveStateMixin,
                FileClosedMixin,
                DistinctDataMixin,
                PollMixin,
+               TtyHangupMixin,
                CloseMixin):
     """
     Helper to avoid cutpasting mixin names below.
     """
 
 
-@unittest2.skipIf(condition=not hasattr(select, 'select'),
-                  reason='select.select() not supported')
 class SelectTest(AllMixin, testlib.TestCase):
     klass = mitogen.core.Poller
 
+SelectTest = unittest2.skipIf(
+    condition=not hasattr(select, 'select'),
+    reason='select.select() not supported'
+)(SelectTest)
+
 
-@unittest2.skipIf(condition=not hasattr(select, 'kqueue'),
-                  reason='select.kqueue() not supported')
 class KqueueTest(AllMixin, testlib.TestCase):
     klass = mitogen.parent.KqueuePoller
 
+KqueueTest = unittest2.skipIf(
+    condition=not hasattr(select, 'kqueue'),
+    reason='select.kqueue() not supported'
+)(KqueueTest)
+
 
-@unittest2.skipIf(condition=not hasattr(select, 'epoll'),
-                  reason='select.epoll() not supported')
 class EpollTest(AllMixin, testlib.TestCase):
     klass = mitogen.parent.EpollPoller
 
+EpollTest = unittest2.skipIf(
+    condition=not hasattr(select, 'epoll'),
+    reason='select.epoll() not supported'
+)(EpollTest)
+
 
 if __name__ == '__main__':
     unittest2.main()