Re: [Qemu-devel] [PATCH 3/9] iotests: Use Python byte strings where appropriate

[Max Reitz <mreitz@redhat.com>]

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On 15.10.18 21:53, Eduardo Habkost wrote:
> On Mon, Oct 15, 2018 at 04:14:47PM +0200, Max Reitz wrote:
>> Since byte strings are no longer the default in Python 3, we have to
>> explicitly use them where we need to, which is mostly when working with
>> structures.  It also means that we need to open a file in binary mode
>> when we want to use structures.
>>
>> On the other hand, we have to accomodate for the fact that some
>> functions (still) work with byte strings but we want to use unicode
>> strings (in Python 3 at least, and it does not matter in Python 2).
>> This includes base64 encoding, but it is most notable when working with
>> the subprocess module: Either we set univeral_newlines to True so that
>> the default streams are opened in text mode (hence this parameter is
>> aliased as "text" as of 3.7), or, if that is not possible, we have to
>> decode the output to a normal string.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
> [...]
>> diff --git a/tests/qemu-iotests/149 b/tests/qemu-iotests/149
>> index 9e0cad76f9..1225334cb8 100755
>> --- a/tests/qemu-iotests/149
>> +++ b/tests/qemu-iotests/149
>> @@ -79,7 +79,7 @@ class LUKSConfig(object):
>>  
>>      def first_password_base64(self):
>>          (pw, slot) = self.first_password()
>> -        return base64.b64encode(pw)
>> +        return base64.b64encode(pw.encode('ascii')).decode('ascii')
> 
> Would we want to have a test case for non-ascii passwords in the
> future?  In that case you would probably need to make
> self.passwords[] contain byte strings instead of text.

I remember someone once providing a non-ASCII initial password to some
system for me.  I remember the system was running Windows, and I was
running Linux, so the system expected ISO-8859-1, while I was sending UTF-8.

The moral of the story is that you probably don't want non-ASCII
passwords.  And if we do want to test them, well, we'll need to decide
on an encoding then (or use byte strings, as you suggest).

> In either case, using 'ascii' as the encoding everywhere will
> ensure the code will not try to be too smart about string
> encodings if that happens.  I like that.
> 
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>

Thanks for reviewing!

Max


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