fix #1179 / linux / cmdline: handle processes erroneously overwriting…

… /proc/pid/cmdline by using spaces instead of null bytes as args separator

HISTORY.rst

@@ -17,6 +17,9 @@
 - 1169_: [Linux] users() "hostname" returns username instead.  (patch by
   janderbrain)
 - 1172_: [Windows] `make test` does not work.
+- 1179_: [Linux] Process.cmdline() correctly splits cmdline args for
+  misbehaving processes who overwrite /proc/pid/cmdline by using spaces
+  instead of null bytes as args separator.
 - 1181_: [OSX] Process.memory_maps() may raise ENOENT.
 
 5.4.1

psutil/_pslinux.py

@@ -1471,9 +1471,17 @@ def cmdline(self):
         if not data:
             # may happen in case of zombie process
             return []
-        if data.endswith('\x00'):
+        # 'man proc' states that args are separated by null bytes '\0'
+        # and last char is supposed to be a null byte. Nevertheless
+        # some processes may change their cmdline after being started
+        # (via setproctitle() or similar), they are usually not
+        # compliant with this rule and use spaces instead. Google
+        # Chrome process is an example. See:
+        # https://github.com/giampaolo/psutil/issues/1179
+        sep = '\x00' if data.endswith('\x00') else ' '
+        if data.endswith(sep):
             data = data[:-1]
-        return [x for x in data.split('\x00')]
+        return [x for x in data.split(sep)]
 
     @wrap_exceptions
     def environ(self):

psutil/tests/test_linux.py

@@ -1585,6 +1585,20 @@ def test_cmdline_mocked(self):
             self.assertEqual(p.cmdline(), ['foo', 'bar', ''])
             assert m.called
 
+    def test_cmdline_spaces_mocked(self):
+        # see: https://github.com/giampaolo/psutil/issues/1179
+        p = psutil.Process()
+        fake_file = io.StringIO(u('foo bar '))
+        with mock.patch('psutil._pslinux.open',
+                        return_value=fake_file, create=True) as m:
+            self.assertEqual(p.cmdline(), ['foo', 'bar'])
+            assert m.called
+        fake_file = io.StringIO(u('foo bar  '))
+        with mock.patch('psutil._pslinux.open',
+                        return_value=fake_file, create=True) as m:
+            self.assertEqual(p.cmdline(), ['foo', 'bar', ''])
+            assert m.called
+
     def test_readlink_path_deleted_mocked(self):
         with mock.patch('psutil._pslinux.os.readlink',
                         return_value='/home/foo (deleted)'):