Add VolumeAction for parsing POOL_NAME:VOLUME_ID

qubes/tools/__init__.py

@@ -198,6 +198,45 @@ class VmNameAction(QubesAction):
                 except KeyError:
                     parser.error('no such domain: {!r}'.format(vm_name))
 
+class VolumeAction(QubesAction):
+    ''' Action for argument parser that gets the
+        :py:class:``qubes.storage.Volume`` from a POOL_NAME:VOLUME_ID string.
+    '''
+    # pylint: disable=too-few-public-methods
+
+    def __init__(self, help='A pool & volume id combination',
+                 required=True, **kwargs):
+        # pylint: disable=redefined-builtin
+        super(VolumeAction, self).__init__(help=help, required=required,
+                                           **kwargs)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        ''' Set ``namespace.vmname`` to ``values`` '''
+        setattr(namespace, self.dest, values)
+
+    def parse_qubes_app(self, parser, namespace):
+        ''' Acquire the :py:class:``qubes.storage.Volume`` object from
+            ``namespace.app``.
+        '''
+        assert hasattr(namespace, 'app')
+        app = namespace.app
+
+        try:
+            pool_name, vid = getattr(namespace, self.dest).split(':')
+            try:
+                pool = app.pools[pool_name]
+                volume = [v for v in pool.volumes if v.vid == vid]
+                assert volume > 1, 'Duplicate vids in pool %s' % pool_name
+                if len(volume) == 0:
+                    parser.error_runtime(
+                        'no volume with id {!r} pool: {!r}'.format(vid,
+                                                                   pool_name))
+                else:
+                    setattr(namespace, self.dest, volume[0])
+            except KeyError:
+                parser.error_runtime('no pool {!r}'.format(pool_name))
+        except ValueError:
+            parser.error('expected a pool & volume id combination like foo:bar')
 
 class PoolsAction(QubesAction):
     ''' Action for argument parser to gather multiple pools '''