Re: [PATCH v3 1/1] python: Update for pylint 2.10

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Sep 15, 2021 at 11:40:31AM -0400, John Snow wrote:
> A few new annoyances. Of note is the new warning for an unspecified
> encoding when opening a text file, which actually does indicate a
> potentially real problem; see
> https://www.python.org/dev/peps/pep-0597/#motivation
> 
> Use LC_CTYPE to determine an encoding to use for interpreting QEMU's
> terminal output. Note that Python states: "language code and encoding
> may be None if their values cannot be determined" -- use a platform
> default as a backup.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/machine/machine.py | 9 ++++++++-
>  python/setup.cfg               | 1 +
>  2 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/python/qemu/machine/machine.py b/python/qemu/machine/machine.py
> index a7081b1845..51b6e79a13 100644
> --- a/python/qemu/machine/machine.py
> +++ b/python/qemu/machine/machine.py
> @@ -19,6 +19,7 @@
>  
>  import errno
>  from itertools import chain
> +import locale
>  import logging
>  import os
>  import shutil
> @@ -290,8 +291,14 @@ def get_pid(self) -> Optional[int]:
>          return self._subp.pid
>  
>      def _load_io_log(self) -> None:
> +        # Assume that the output encoding of QEMU's terminal output
> +        # is defined by our locale. If indeterminate, use a platform default.
> +        _, encoding = locale.getlocale()
> +        if encoding is None:
> +            encoding = locale.getpreferredencoding(do_setlocale=False)

Do we really need this getpreferredencoding ?  IIUC, this is a sign
that the application is buggy by not calling

  locale.setlocale(locale.LC_ALL, '')

during its main() method, which I think we can just delegate to the
code in question to fix. Missing setlocale will affect everything
they run, so doing workarounds in only 1 place is not worth it IMHO

>          if self._qemu_log_path is not None:
> -            with open(self._qemu_log_path, "r") as iolog:
> +            with open(self._qemu_log_path, "r",
> +                      encoding=encoding) as iolog:
>                  self._iolog = iolog.read()
Regards,
Daniel
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