Re: [Qemu-devel] [PATCH v12 1/6] qemu.py: better control of created files

[Eduardo Habkost <ehabkost@redhat.com>]

On Mon, Jan 22, 2018 at 09:50:28PM +0100, Amador Pahim wrote:
> To launch a VM, we need to create basically two files: the monitor
> socket (if it's a UNIX socket) and the qemu log file.
> 
> For the qemu log file, we currently just open the path, which will
> create the file if it does not exist or overwrite the file if it does
> exist.
> 
> For the monitor socket, if it already exists, we are currently removing
> it, even if it's not created by us.
> 
> This patch moves to _pre_launch() the responsibility to create a
> temporary directory to host the files so we can remove the whole
> directory on _post_shutdown().
> 
> Signed-off-by: Amador Pahim <apahim@redhat.com>
> ---
>  scripts/qemu.py | 39 +++++++++++++++++++++++++++++----------
>  1 file changed, 29 insertions(+), 10 deletions(-)
> 
> diff --git a/scripts/qemu.py b/scripts/qemu.py
> index 9bfdf6d37d..453a67250a 100644
> --- a/scripts/qemu.py
> +++ b/scripts/qemu.py
> @@ -18,6 +18,8 @@ import os
>  import sys
>  import subprocess
>  import qmp.qmp
> +import shutil
> +import tempfile
>  
>  
>  LOG = logging.getLogger(__name__)
> @@ -73,10 +75,11 @@ class QEMUMachine(object):
>              wrapper = []
>          if name is None:
>              name = "qemu-%d" % os.getpid()
> -        if monitor_address is None:
> -            monitor_address = os.path.join(test_dir, name + "-monitor.sock")
> +        self._name = name
>          self._monitor_address = monitor_address
> -        self._qemu_log_path = os.path.join(test_dir, name + ".log")
> +        self._vm_monitor = None
> +        self._qemu_log_path = None
> +        self._qemu_log_file = None
>          self._popen = None
>          self._binary = binary
>          self._args = list(args)     # Force copy args in case we modify them
> @@ -86,6 +89,8 @@ class QEMUMachine(object):
>          self._socket_scm_helper = socket_scm_helper
>          self._qmp = None
>          self._qemu_full_args = None
> +        self._test_dir = test_dir
> +        self._temp_dir = None
>  
>          # just in case logging wasn't configured by the main script:
>          logging.basicConfig()
> @@ -168,36 +173,50 @@ class QEMUMachine(object):
>                  self._monitor_address[0],
>                  self._monitor_address[1])

If _monitor_address now needs to be translated to _vm_monitor,
I'd like to remove all usage of _monitor_address outside
_pre_launch, to avoid confusion between the two attributes.

This can be done in a follow-up patch.

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>

>          else:
> -            moncdev = 'socket,id=mon,path=%s' % self._monitor_address
> +            moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
>          return ['-chardev', moncdev,
>                  '-mon', 'chardev=mon,mode=control',
>                  '-display', 'none', '-vga', 'none']
>  
>      def _pre_launch(self):
> -        self._qmp = qmp.qmp.QEMUMonitorProtocol(self._monitor_address,
> +        self._temp_dir = tempfile.mkdtemp(dir=self._test_dir)
> +        if self._monitor_address is not None:
> +            self._vm_monitor = self._monitor_address
> +        else:
> +            self._vm_monitor = os.path.join(self._temp_dir,
> +                                            self._name + "-monitor.sock")
> +        self._qemu_log_path = os.path.join(self._temp_dir, self._name + ".log")
> +        self._qemu_log_file = open(self._qemu_log_path, 'wb')
> +
> +        self._qmp = qmp.qmp.QEMUMonitorProtocol(self._vm_monitor,
>                                                  server=True)
>  
>      def _post_launch(self):
>          self._qmp.accept()
>  
>      def _post_shutdown(self):
> -        if not isinstance(self._monitor_address, tuple):
> -            self._remove_if_exists(self._monitor_address)
> -        self._remove_if_exists(self._qemu_log_path)
> +        if self._qemu_log_file is not None:
> +            self._qemu_log_file.close()
> +            self._qemu_log_file = None
> +
> +        self._qemu_log_path = None
> +
> +        if self._temp_dir is not None:
> +            shutil.rmtree(self._temp_dir)
> +            self._temp_dir = None
>  
>      def launch(self):
>          '''Launch the VM and establish a QMP connection'''
>          self._iolog = None
>          self._qemu_full_args = None
>          devnull = open(os.path.devnull, 'rb')
> -        qemulog = open(self._qemu_log_path, 'wb')
>          try:
>              self._pre_launch()
>              self._qemu_full_args = (self._wrapper + [self._binary] +
>                                      self._base_args() + self._args)
>              self._popen = subprocess.Popen(self._qemu_full_args,
>                                             stdin=devnull,
> -                                           stdout=qemulog,
> +                                           stdout=self._qemu_log_file,
>                                             stderr=subprocess.STDOUT,
>                                             shell=False)
>              self._post_launch()
> -- 
> 2.14.3
> 
> 

-- 
Eduardo