Don't return null-byte separated string from ExternalProcess.cmdline()

Instead construct the string using psutil.Process.cmdline() method that
will parse the data from kernel for us and will return a proper
space-separated command line (plus will provide some more safety
guarantees, e.g. against zombies).

This change also introduces a new psutil dependency for neutron. Before
that, the library was used in functional tests only, and with a minimal
version number that is not compatible with global-requirements.txt or
.cmdline(). Moved the requirement into runtime requirements.

Related-Bug: #1672921
Change-Id: I780ea10bd1870c86c1a048071863843bc2993958

neutron/agent/linux/external_process.py

@@ -21,6 +21,7 @@ from oslo_concurrency import lockutils
 from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_utils import fileutils
+import psutil
 import six
 
 from neutron._i18n import _, _LW, _LE
@@ -146,12 +147,9 @@ class ProcessManager(MonitoredProcess):
         pid = self.pid
         if not pid:
             return
-
-        cmdline = '/proc/%s/cmdline' % pid
         try:
-            with open(cmdline, "r") as f:
-                return f.readline()
-        except IOError:
+            return ' '.join(psutil.Process(pid).cmdline())
+        except (psutil.NoSuchProcess, psutil.AccessDenied):
             return
 
 

neutron/tests/functional/requirements.txt

@@ -4,5 +4,4 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-psutil>=1.1.1,<2.0.0
 psycopg2

neutron/tests/unit/agent/linux/test_external_process.py

@@ -16,6 +16,7 @@ import mock
 import os.path
 
 from oslo_utils import fileutils
+import psutil
 
 from neutron.agent.linux import external_process as ep
 from neutron.tests import base
@@ -285,22 +286,19 @@ class TestProcessManager(base.BaseTestCase):
             self.assertFalse(manager.active)
 
     def test_cmdline(self):
-        mock_open = self.useFixture(
-            tools.OpenFixture('/proc/4/cmdline', TEST_CMDLINE % 'uuid')
-        ).mock_open
-        with mock.patch.object(ep.ProcessManager, 'pid') as pid:
-            pid.__get__ = mock.Mock(return_value=4)
-            manager = ep.ProcessManager(self.conf, 'uuid')
-            self.assertEqual(TEST_CMDLINE % 'uuid', manager.cmdline)
-        mock_open.assert_called_once_with('/proc/4/cmdline', 'r')
+        with mock.patch.object(psutil, 'Process') as proc:
+            proc().cmdline.return_value = (TEST_CMDLINE % 'uuid').split(' ')
+            with mock.patch.object(ep.ProcessManager, 'pid') as pid:
+                pid.__get__ = mock.Mock(return_value=4)
+                manager = ep.ProcessManager(self.conf, 'uuid')
+                self.assertEqual(TEST_CMDLINE % 'uuid', manager.cmdline)
+        proc().cmdline.assert_called_once_with()
 
     def test_cmdline_none(self):
-        mock_open = self.useFixture(
-            tools.OpenFixture('/proc/4/cmdline', TEST_CMDLINE % 'uuid')
-        ).mock_open
-        mock_open.side_effect = IOError()
-        with mock.patch.object(ep.ProcessManager, 'pid') as pid:
-            pid.__get__ = mock.Mock(return_value=4)
-            manager = ep.ProcessManager(self.conf, 'uuid')
-            self.assertIsNone(manager.cmdline)
-        mock_open.assert_called_once_with('/proc/4/cmdline', 'r')
+        with mock.patch.object(psutil, 'Process') as proc:
+            proc.side_effect = psutil.NoSuchProcess(4)
+            with mock.patch.object(ep.ProcessManager, 'pid') as pid:
+                pid.__get__ = mock.Mock(return_value=4)
+                manager = ep.ProcessManager(self.conf, 'uuid')
+                self.assertIsNone(manager.cmdline)
+        proc.assert_called_once_with(4)

requirements.txt

@@ -44,6 +44,7 @@ oslo.utils>=3.20.0 # Apache-2.0
 oslo.versionedobjects>=1.17.0 # Apache-2.0
 osprofiler>=1.4.0 # Apache-2.0
 ovs>=2.6.1 # Apache-2.0
+psutil>=3.2.2  # BSD
 pyroute2>=0.4.12 # Apache-2.0 (+ dual licensed GPL2)
 weakrefmethod>=1.0.2;python_version=='2.7' # PSF