Re: [Libguestfs] Extending the nbdkit python plugin
On Thu, Nov 21, 2019 at 02:17:43PM +0000, Daniel P. Berrangé wrote:
I would define a new 'api_version()' method for your python
plugins.
Existing plugins don't implement that of course so when your
C code invokes that it'll get an exception, and can assume
the classic API contract for pwrite().
If the plugin implements 'api_version()' returning '1' (or
whatever), then this should inform the C code that the plugin
has the 4 arg variant of pwrite().
I suspect this has to be the way to go. One reason is that
the V1 zero API is defined as:
def zero(h, count, offset, may_trim=False):
but in V2 we'd like to replace the fourth parameter with a flags
bitmask. I believe pure introspection can never detect this.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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