qemu.py: use poll() instead of 'returncode'

The 'returncode' Popen attribute is not guaranteed to be updated. It
actually depends on a call to either poll(), wait() or communicate().

On the other hand, poll() will: "Check if child process has terminated.
Set and return returncode attribute."

Let's use the poll() to check whether the process is running and to get
the updated process exit code, when the process is finished.

Reviewed-by: Fam Zheng <famz@redhat.com>
eviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Amador Pahim <apahim@redhat.com>
Message-Id: <20180122205033.24893-5-apahim@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

diff --git a/scripts/qemu.py b/scripts/qemu.py
index 52cf09eebd64812ab73ec4278e5b9d3dc503b834..dcb4f0ffe6461f8bee49c6d29f0c839e00d633c5 100644 (file)
--- a/scripts/qemu.py
+++ b/scripts/qemu.py
@@ -150,12 +150,12 @@ class QEMUMachine(object):
             raise
 
     def is_running(self):
-        return self._popen is not None and self._popen.returncode is None
+        return self._popen is not None and self._popen.poll() is None
 
     def exitcode(self):
         if self._popen is None:
             return None
-        return self._popen.returncode
+        return self._popen.poll()
 
     def get_pid(self):
         if not self.is_running():