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Date: Thu, 14 Sep 2017 17:18:53 -0300
From: Eduardo Habkost <ehabkost@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v8 06/13] qemu.py: make sure we only remove
 files we create
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To: Amador Pahim <apahim@redhat.com>
Cc: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@gmail.com>, Daniel Berrange <berrange@redhat.com>, Max Reitz <mreitz@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Markus Armbruster <armbru@redhat.com>, Cleber Rosa <crosa@redhat.com>, =?utf-8?B?THVrw6HFoQ==?= Doktor <ldoktor@redhat.com>

On Thu, Sep 14, 2017 at 10:05:50PM +0200, Amador Pahim wrote:
> On Thu, Sep 14, 2017 at 9:46 PM, Eduardo Habkost <ehabkost@redhat.com> wrote:
> > On Thu, Sep 14, 2017 at 09:38:13PM +0200, Amador Pahim wrote:
> >> On Tue, Sep 5, 2017 at 5:18 AM, Fam Zheng <famz@redhat.com> wrote:
> >> > On Fri, 09/01 13:28, Amador Pahim wrote:
[...]
> >> >> +        else:
> >> >> +            if not isinstance(self._monitor_address, tuple):
> >> >> +                self._created_files.append(self._monitor_address)
> >> >> +
> >> >> +        try:
> >> >> +            flags = os.O_CREAT | os.O_EXCL | os.O_WRONLY
> >> >> +            os.open(self._qemu_log_path, flags)
> >> >
> >> > Why change to os.open() instead of open()?
> >>
> >> I want to create the file only if it does not exist. The open() flag
> >> 'x' is available only in python 3.3. For python <3.3, we need the
> >> os.open() to have that feature.
> >
> > I'm not sure this extra complexity is really necessary.  We could
> > fix all that by using mkdtemp() and deleting the temporary
> > directory on shutdown.
> 
> I thought about that, but I foresee the question: hat happens if
> between the mkdtemp and the file creation (i.e. self._qemu_log_path)
> someone goes in that directory and creates a file with the same name
> of the self._qemu_log_path? Are we going to overwrite it? Ok, very
> unlikely, but possible. This extra step takes care of that.

If someone creates a file inside a directory we created using
mkdtemp(), we will just delete it.  Why would that be a problem?

-- 
Eduardo