From: Lukáš Doktor <ldok...@redhat.com> The list object is mutable in python and potentially might modify other object's arguments when used as default argument. Reproducer:
>>> vm1 = QEMUMachine("qemu") >>> vm2 = QEMUMachine("qemu") >>> vm1._wrapper.append("foo") >>> print vm2._wrapper ['foo'] In this case the `args` is actually copied so it would be safe to keep it, but it's not a good practice to keep it. The same issue applies in inherited qtest module. Signed-off-by: Lukáš Doktor <ldok...@redhat.com> Reviewed-by: Eduardo Habkost <ehabk...@redhat.com> Reviewed-by: John Snow <js...@redhat.com> Message-Id: <20170818142613.32394-3-ldok...@redhat.com> Reviewed-by: Cleber Rosa <cr...@redhat.com> Signed-off-by: Eduardo Habkost <ehabk...@redhat.com> --- scripts/qemu.py | 6 +++++- scripts/qtest.py | 2 +- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/scripts/qemu.py b/scripts/qemu.py index b45e691538..afd98a290e 100644 --- a/scripts/qemu.py +++ b/scripts/qemu.py @@ -30,7 +30,7 @@ class QEMUMachine(object): # vm is guaranteed to be shut down here ''' - def __init__(self, binary, args=[], wrapper=[], name=None, + def __init__(self, binary, args=None, wrapper=None, name=None, test_dir="/var/tmp", monitor_address=None, socket_scm_helper=None, debug=False): ''' @@ -46,6 +46,10 @@ class QEMUMachine(object): @param debug: enable debug mode @note: Qemu process is not started until launch() is used. ''' + if args is None: + args = [] + if wrapper is None: + wrapper = [] if name is None: name = "qemu-%d" % os.getpid() if monitor_address is None: diff --git a/scripts/qtest.py b/scripts/qtest.py index d5aecb5f49..ab183c0635 100644 --- a/scripts/qtest.py +++ b/scripts/qtest.py @@ -79,7 +79,7 @@ class QEMUQtestProtocol(object): class QEMUQtestMachine(qemu.QEMUMachine): '''A QEMU VM''' - def __init__(self, binary, args=[], name=None, test_dir="/var/tmp", + def __init__(self, binary, args=None, name=None, test_dir="/var/tmp", socket_scm_helper=None): if name is None: name = "qemu-%d" % os.getpid() -- 2.13.5