Re: [Qemu-devel] [PATCH] tests: Force Python I/O encoding for check-qapi-schema

[Markus Armbruster <armbru@redhat.com>]

Eduardo Habkost <ehabkost@redhat.com> writes:

> On Tue, May 07, 2019 at 03:13:45PM +0100, Daniel P. Berrangé wrote:
>> On Mon, May 06, 2019 at 06:38:17PM -0300, Eduardo Habkost wrote:
>> > test-qapi.py doesn't force a specific encoding for stderr or
>> > stdout, but the reference files used by check-qapi-schema are in
>> > UTF-8.  This breaks check-qapi-schema under certain circumstances
>> > (e.g. if using the C locale and Python < 3.7).
>> > 
>> > We need to make sure test-qapi.py always generate UTF-8 output
>> > somehow.  On Python 3.7+ we can do it using
>> > `sys.stdout.reconfigure(...)`, but we need a solution that works
>> > with older Python versions.
>> > 
>> > Instead of trying a hack like reopening sys.stdout and
>> > sys.stderr, we can just tell Python to use UTF-8 for I/O encoding
>> > when running test-qapi.py.  Do it by setting PYTHONIOENCODING.
>> > 
>> > Reported-by: Thomas Huth <thuth@redhat.com>
>> > Tested-by: Thomas Huth <thuth@redhat.com>
>> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
>> > ---
>> >  tests/Makefile.include | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> > 
>> > diff --git a/tests/Makefile.include b/tests/Makefile.include
>> > index 7c8b9c84b2..af88ab6f8b 100644
>> > --- a/tests/Makefile.include
>> > +++ b/tests/Makefile.include
>> > @@ -1103,7 +1103,7 @@ check-tests/qemu-iotests-quick.sh: tests/qemu-iotests-quick.sh qemu-img$(EXESUF)
>> >  .PHONY: $(patsubst %, check-%, $(check-qapi-schema-y))
>> >  $(patsubst %, check-%, $(check-qapi-schema-y)): check-%.json: $(SRC_PATH)/%.json
>> >  	$(call quiet-command, PYTHONPATH=$(SRC_PATH)/scripts \
>> > -		$(PYTHON) $(SRC_PATH)/tests/qapi-schema/test-qapi.py \
>> > +		PYTHONIOENCODING=utf-8 $(PYTHON) $(SRC_PATH)/tests/qapi-schema/test-qapi.py \
>> 
>> I see PYTHONIOENCODING exists since 2.6 which is nice.
>> 
>> How about we actually change $(PYTHON) so that it always includes
>> PYTHONIOENCODING=utf-8 ?
>> 
>> That way we avoid continuing to play whack-a-mole with more utf-8
>> bugs in future.
>> 
>> It would also let us revert this:
>> 
>>   commit de685ae5e9a4b523513033bd6cadc8187a227170
>>   Author: Markus Armbruster <armbru@redhat.com>
>>   Date:   Mon Jun 18 19:59:57 2018 +0200
>> 
>>     qapi: Open files with encoding='utf-8'
>> 
>> which had to provide separate logic for py2 vs py3 :-(

The separate logic will soon be history.  I'd welcome getting rid of the
remainder anyway.

> Not every Python script in the QEMU tree is run by our makefiles
> and scripts using $(PYTHON).  We need to ensure our scripts and
> modules won't break when run directly from the command line, too.
> Setting PYTHONIOENCODING everywhere would just hide these bugs
> from us.

I agree for Python scripts that are meant to be run that way (assuming
such scripts exist).  For all the others (including all the QAPI-related
scripts), I'd be quite fine with

1. Our build system runs all Python scripts with the
PYTHONIOENCODING=utf-8

2. If you run a Python script yourself, you get to specify the
PYTHONIOENCODING=utf-8, or use a suitable locale.  Enabling UTF-8 mode
with PYTHONUTF8=1 or -X utf8 could also work.