On 04.10.2016 10:43, Kashyap Chamarthy wrote:
> Last night I was trying to check whether blockJobInfo() method will
> raise an error when it returns 'None' in v1.2.5 libvirt Python bindings.
> (Eric Blake confirmed on IRC: "the python bindings have, as a general
> rule, always raised a libvirtError if the C binding code returns None").
>
> Before asking on IRC, I built the bindings and the below is what I noticed.
>
> Let's first see what's in current Git master:
>
> $ less build/libvirt.py
> [...]
> def blockJobInfo(self, path, flags=0):
> """Get progress information for a block job """
> ret = libvirtmod.virDomainGetBlockJobInfo(self._o, path, flags)
> if ret is None: raise libvirtError ('virDomainGetBlockJobInfo() failed', dom=self)
> return ret
> [...]
>
> Now try to find out what is present in v1.2.5 by quickly building the
> bindings for that tag:
>
> $ git checkout v1.2.5
> $ python setup.py build
>
> Hmm, once built, there's no blockJobInfo() method in build/libvirt.py!
> (When I mentioned this on #virt, OFTC, Cole confirmed he could reproduce
> the behavior, too. Not sure if it's a regression in v1.2.5.)
I've bisected this one down to 8e09c79a07b097a6ba9af83be4916fb9c9538500:
$ git describe --contains 8e09c79a07b097a6ba9af83be4916fb9c9538500
v1.2.10^0
It's a result of a split of python bindings we made a long time ago.
>
> However, the libvirt "glue code" for libvirt_virDomainGetBlockJobInfo()
> exists in libvirt-python/libvirt-override.c, so checking there (again,
> for v1.2.5), we see:
>
> 4755 if (c_ret == 0) {
> 4756 return dict;
> 4757 } else if (c_ret < 0) {
> 4758 Py_DECREF(dict);
> 4759 return VIR_PY_NONE;
> 4760 }
>
> IIUC, the VIR_PY_NONE means it raises an exception (libvirtError).
>
Correct, the exception is raised in C API fails. Note, that it is not
considered a failure if there's no job running (in which case an empty
dict is returned).
Michal
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