[02/10] python/machine: use subprocess.DEVNULL instead of open(os.path.devnull)

Commit Message

John Snow May 12, 2021, 9:46 p.m. UTC

One less file resource to manage, and it helps quiet some pylint >=
2.8.0 warnings about not using a with-context manager for the open call.

Signed-off-by: John Snow <[e-mail]>
---
 python/qemu/machine.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Comments

Philippe Mathieu-Daudé May 13, 2021, 9:39 a.m. UTC | #1

On 5/12/21 11:46 PM, John Snow wrote:
> One less file resource to manage, and it helps quiet some pylint >=
> 2.8.0 warnings about not using a with-context manager for the open call.
> 
> Signed-off-by: John Snow <[e-mail]>
> ---
>  python/qemu/machine.py | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>

Patch

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 6e44bda337e..41f51bd27d0 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -223,9 +223,8 @@  def send_fd_scm(self, fd: Optional[int] = None,
             assert fd is not None
             fd_param.append(str(fd))
 
-        devnull = open(os.path.devnull, 'rb')
         proc = subprocess.Popen(
-            fd_param, stdin=devnull, stdout=subprocess.PIPE,
+            fd_param, stdin=subprocess.DEVNULL, stdout=subprocess.PIPE,
             stderr=subprocess.STDOUT, close_fds=False
         )
         output = proc.communicate()[0]
@@ -393,7 +392,6 @@  def _launch(self) -> None:
         """
         Launch the VM and establish a QMP connection
         """
-        devnull = open(os.path.devnull, 'rb')
         self._pre_launch()
         self._qemu_full_args = tuple(
             chain(self._wrapper,
@@ -403,7 +401,7 @@  def _launch(self) -> None:
         )
         LOG.debug('VM launch command: %r', ' '.join(self._qemu_full_args))
         self._popen = subprocess.Popen(self._qemu_full_args,
-                                       stdin=devnull,
+                                       stdin=subprocess.DEVNULL,
                                        stdout=self._qemu_log_file,
                                        stderr=subprocess.STDOUT,
                                        shell=False,