Avoid cyclic imports

QubesOS/qubes-issues#853

ci/pylintrc

@@ -6,7 +6,6 @@ ignore=tests
 # abstract-class-little-used: see http://www.logilab.org/ticket/111138
 disable=
   bad-continuation,
-  cyclic-import,
   fixme,
   locally-disabled,
   missing-docstring

qubesmgmt/__init__.py

@@ -19,140 +19,12 @@
 # with this program; if not, see <http://www.gnu.org/licenses/>.
 
 
-import ast
 import os
-
+import qubesmgmt.base
-import qubesmgmt.exc
-
-DEFAULT = object()
-
-
-class PropertyHolder(object):
-    '''A base class for object having properties retrievable using mgmt API.
-
-    Warning: each (non-private) local attribute needs to be defined at class
-    level, even if initialized in __init__; otherwise will be treated as
-    property retrievable using mgmt call.
-    '''
-    #: a place for appropriate Qubes() object (QubesLocal or QubesRemote),
-    # use None for self
-    app = None
-
-    def __init__(self, app, method_prefix, method_dest):
-        #: appropriate Qubes() object (QubesLocal or QubesRemote), use None
-        # for self
-        self.app = app
-        self._method_prefix = method_prefix
-        self._method_dest = method_dest
-        self._properties = None
-        self._properties_help = None
-
-    def qubesd_call(self, dest, method, arg=None, payload=None):
-        '''
-        Call into qubesd using appropriate mechanism. This method should be
-        defined by a subclass.
-
-        :param dest: Destination VM name
-        :param method: Full API method name ('mgmt...')
-        :param arg: Method argument (if any)
-        :param payload: Payload send to the method
-        :return: Data returned by qubesd (string)
-        '''
-        # have the actual implementation at Qubes() instance
-        if self.app:
-            return self.app.qubesd_call(dest, method, arg, payload)
-        raise NotImplementedError
-
-    @staticmethod
-    def _parse_qubesd_response(response_data):
-        if response_data[0:2] == b'\x30\x00':
-            return response_data[2:]
-        elif response_data[0:2] == b'\x32\x00':
-            (_, exc_type, _traceback, format_string, args) = \
-                response_data.split(b'\x00', 4)
-            # drop last field because of terminating '\x00'
-            args = [arg.decode() for arg in args.split(b'\x00')[:-1]]
-            format_string = format_string.decode('utf-8')
-            exc_type = exc_type.decode('ascii')
-            exc_class = getattr(qubesmgmt.exc, exc_type, 'QubesException')
-            # TODO: handle traceback if given
-            raise exc_class(format_string, *args)
-        else:
-            raise qubesmgmt.exc.QubesException('Invalid response format')
-
-
-    def property_list(self):
-        if self._properties is None:
-            properties_str = self.qubesd_call(
-                self._method_dest,
-                self._method_prefix + 'List',
-                None,
-                None)
-            self._properties = properties_str.decode('ascii').splitlines()
-        # TODO: make it somehow immutable
-        return self._properties
-
-    def property_is_default(self, item):
-        if item.startswith('_'):
-            raise AttributeError(item)
-        property_str = self.qubesd_call(
-                self._method_dest,
-                self._method_prefix + 'Get',
-                item,
-                None)
-        (default, _value) = property_str.split(b' ', 1)
-        assert default.startswith(b'default=')
-        is_default_str = default.split(b'=')[1]
-        is_default = ast.literal_eval(is_default_str.decode('ascii'))
-        assert isinstance(is_default, bool)
-        return is_default
-
-    def __getattr__(self, item):
-        if item.startswith('_'):
-            raise AttributeError(item)
-        property_str = self.qubesd_call(
-                self._method_dest,
-                self._method_prefix + 'Get',
-                item,
-                None)
-        (_default, value) = property_str.split(b' ', 1)
-        value = value.decode()
-        if value[0] == '\'':
-            return ast.literal_eval('u' + value)
-        else:
-            return ast.literal_eval(value)
-
-    def __setattr__(self, key, value):
-        if key.startswith('_') or key in dir(self):
-            return super(PropertyHolder, self).__setattr__(key, value)
-        if value is DEFAULT:
-            self.qubesd_call(
-                self._method_dest,
-                self._method_prefix + 'Reset',
-                key,
-                None)
-        else:
-            if isinstance(value, qubesmgmt.vm.QubesVM):
-                # pylint: disable=protected-access
-                value = value._name
-            self.qubesd_call(
-                self._method_dest,
-                self._method_prefix + 'Set',
-                key,
-                str(value).encode('utf-8'))
-
-    def __delattr__(self, name):
-        if name.startswith('_') or name in dir(self):
-            return super(PropertyHolder, self).__delattr__(name)
-        self.qubesd_call(
-            self._method_dest,
-            self._method_prefix + 'Reset',
-            name
-        )
-
-# pylint: disable=wrong-import-position
 import qubesmgmt.app
 
+DEFAULT = qubesmgmt.base.DEFAULT
+
 if os.path.exists(qubesmgmt.app.QUBESD_SOCK):
     Qubes = qubesmgmt.app.QubesLocal
 else:

qubesmgmt/app.py

@@ -22,7 +22,7 @@ import socket
 
 import subprocess
 
-import qubesmgmt
+import qubesmgmt.base
 import qubesmgmt.vm
 import qubesmgmt.exc
 
@@ -71,7 +71,7 @@ class VMCollection(object):
         return self._vm_list.keys()
 
 
-class QubesBase(qubesmgmt.PropertyHolder):
+class QubesBase(qubesmgmt.base.PropertyHolder):
     '''Main Qubes application'''
 
     #: domains (VMs) collection

qubesmgmt/base.py

@@ -0,0 +1,156 @@
+# -*- encoding: utf8 -*-
+#
+# The Qubes OS Project, http://www.qubes-os.org
+#
+# Copyright (C) 2017 Marek Marczykowski-Górecki
+#                               <marmarek@invisiblethingslab.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with this program; if not, see <http://www.gnu.org/licenses/>.
+import ast
+import qubesmgmt.exc
+
+DEFAULT = object()
+
+class PropertyHolder(object):
+    '''A base class for object having properties retrievable using mgmt API.
+
+    Warning: each (non-private) local attribute needs to be defined at class
+    level, even if initialized in __init__; otherwise will be treated as
+    property retrievable using mgmt call.
+    '''
+    #: a place for appropriate Qubes() object (QubesLocal or QubesRemote),
+    # use None for self
+    app = None
+
+    def __init__(self, app, method_prefix, method_dest):
+        #: appropriate Qubes() object (QubesLocal or QubesRemote), use None
+        # for self
+        self.app = app
+        self._method_prefix = method_prefix
+        self._method_dest = method_dest
+        self._properties = None
+        self._properties_help = None
+
+    def qubesd_call(self, dest, method, arg=None, payload=None):
+        '''
+        Call into qubesd using appropriate mechanism. This method should be
+        defined by a subclass.
+
+        :param dest: Destination VM name
+        :param method: Full API method name ('mgmt...')
+        :param arg: Method argument (if any)
+        :param payload: Payload send to the method
+        :return: Data returned by qubesd (string)
+        '''
+        # have the actual implementation at Qubes() instance
+        if self.app:
+            return self.app.qubesd_call(dest, method, arg, payload)
+        raise NotImplementedError
+
+    @staticmethod
+    def _parse_qubesd_response(response_data):
+        if response_data[0:2] == b'\x30\x00':
+            return response_data[2:]
+        elif response_data[0:2] == b'\x32\x00':
+            (_, exc_type, _traceback, format_string, args) = \
+                response_data.split(b'\x00', 4)
+            # drop last field because of terminating '\x00'
+            args = [arg.decode() for arg in args.split(b'\x00')[:-1]]
+            format_string = format_string.decode('utf-8')
+            exc_type = exc_type.decode('ascii')
+            exc_class = getattr(qubesmgmt.exc, exc_type, 'QubesException')
+            # TODO: handle traceback if given
+            raise exc_class(format_string, *args)
+        else:
+            raise qubesmgmt.exc.QubesException('Invalid response format')
+
+    def property_list(self):
+        '''
+        List available properties (their names).
+
+        :return: list of strings
+        '''
+        if self._properties is None:
+            properties_str = self.qubesd_call(
+                self._method_dest,
+                self._method_prefix + 'List',
+                None,
+                None)
+            self._properties = properties_str.decode('ascii').splitlines()
+        # TODO: make it somehow immutable
+        return self._properties
+
+    def property_is_default(self, item):
+        '''
+        Check if given property have default value
+
+        :param str item: name of property
+        :return: bool
+        '''
+        if item.startswith('_'):
+            raise AttributeError(item)
+        property_str = self.qubesd_call(
+            self._method_dest,
+            self._method_prefix + 'Get',
+            item,
+            None)
+        (default, _value) = property_str.split(b' ', 1)
+        assert default.startswith(b'default=')
+        is_default_str = default.split(b'=')[1]
+        is_default = ast.literal_eval(is_default_str.decode('ascii'))
+        assert isinstance(is_default, bool)
+        return is_default
+
+    def __getattr__(self, item):
+        if item.startswith('_'):
+            raise AttributeError(item)
+        property_str = self.qubesd_call(
+            self._method_dest,
+            self._method_prefix + 'Get',
+            item,
+            None)
+        (_default, value) = property_str.split(b' ', 1)
+        value = value.decode()
+        if value[0] == '\'':
+            return ast.literal_eval('u' + value)
+        else:
+            return ast.literal_eval(value)
+
+    def __setattr__(self, key, value):
+        if key.startswith('_') or key in dir(self):
+            return super(PropertyHolder, self).__setattr__(key, value)
+        if value is qubesmgmt.DEFAULT:
+            self.qubesd_call(
+                self._method_dest,
+                self._method_prefix + 'Reset',
+                key,
+                None)
+        else:
+            if isinstance(value, qubesmgmt.vm.QubesVM):
+                # pylint: disable=protected-access
+                value = value._name
+            self.qubesd_call(
+                self._method_dest,
+                self._method_prefix + 'Set',
+                key,
+                str(value).encode('utf-8'))
+
+    def __delattr__(self, name):
+        if name.startswith('_') or name in dir(self):
+            return super(PropertyHolder, self).__delattr__(name)
+        self.qubesd_call(
+            self._method_dest,
+            self._method_prefix + 'Reset',
+            name
+        )

qubesmgmt/vm/__init__.py

@@ -18,10 +18,10 @@
 # You should have received a copy of the GNU General Public License along
 # with this program; if not, see <http://www.gnu.org/licenses/>.
 
-import qubesmgmt
+import qubesmgmt.base
 
 
-class QubesVM(qubesmgmt.PropertyHolder):
+class QubesVM(qubesmgmt.base.PropertyHolder):
     def __init__(self, app, name, vm_class):
         self._name = name
         self._class = vm_class