[virt-tools-list] [virt-manager PATCH] formats: make sure 'unar' is existed

[Cole Robinson]

On 03/04/2014 11:02 AM, Cole Robinson wrote:
> On 03/04/2014 04:06 AM, Martin Kletzander wrote:
>> On Tue, Mar 04, 2014 at 04:16:58PM +0800, Chen Hanxiao wrote:
>>> Commit 0b4a72fd77f74e5a9f6885179febe601156df617
>>> needs unar command to do some tests.
>>>
>>> But if we haven't installed it, the error message
>>> told us nothing valuable as:
>>> "OSError: [Errno 2] No such file or directory"
>>>
>>> This patch will impove the error message.
>>>
>>> Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
>>> ---
>>
>> I got to the bottom of this when I first saw the error and after some
>> time installed it.  But since you're posting this question, shouldn't
>> we put unar into .spec.in file and check for it while running
>> setup.py?
>>
> 
> Were you guys hitting this from the test suite?
> 
>> Or even better, can't we use something else than unar since on source
>> distributions this requires objective C compiler and some other not
>> very usual packages.  It seems a little bit cumbersome for some users;
>> and yes, I understand it's the minimum, but if there's an easier way
>> than we may as well be nice.
>>
> 
> Hmm, didn't realize unar wasn't just a plain C app. That makes adding an
> explicit dep kind of annoying.
> 
> Since it's only used as a convenience functionality of unarchiving a tar.gz or
> zip or xz, we can just fail if unar isn't available and tell the user to
> extract the directory themselves, and then point virt-convert at the
> directory. For the test suite, we can just duplicate the unar check and skip
> the tests if it's not available.

The more thorough alternative is to call out to xz, tar, bzip2 etc as dictated
by the file extension... but that's a decent chunk of work and IMO isn't worth
the effort for a tool with such few users.

- Cole