QubesVm: introduce hooks for plugins

Besides introducing new VM classes, plugins may influence existing VM
behavior. Introduce convenient hooks for it. Without those hooks it still was
possible, but in much less correct way - overriding class methods from
plugin module.

dom0/core-modules/000QubesVm.py

@@ -51,6 +51,23 @@ class QubesVm(object):
     # In which order load this VM type from qubes.xml
     load_order = 100
 
+    # hooks for plugins (modules) which want to influence existing classes,
+    # without introducing new ones
+    hooks_clone_disk_files = []
+    hooks_create_on_disk = []
+    hooks_create_xenstore_entries = []
+    hooks_get_attrs_config = []
+    hooks_get_clone_attrs = []
+    hooks_get_config_params = []
+    hooks_init = []
+    hooks_label_setter = []
+    hooks_netvm_setter = []
+    hooks_post_rename = []
+    hooks_pre_rename = []
+    hooks_remove_from_disk = []
+    hooks_start = []
+    hooks_verify_files = []
+
     def get_attrs_config(self):
         """ Object attributes for serialization/deserialization
             inner dict keys:
@@ -138,6 +155,9 @@ class QubesVm(object):
         attrs['template']['save_attr'] = "template_qid"
         attrs['label']['save'] = 'self.label.name'
 
+        # fire hooks
+        for hook in self.hooks_get_attrs_config:
+            attrs = hook(self, attrs)
         return attrs
 
     def __basic_parse_xml_attr(self, value):
@@ -236,6 +256,10 @@ class QubesVm(object):
         self.xid = -1
         self.xid = self.get_xid()
 
+        # fire hooks
+        for hook in self.hooks_init:
+            hook(self)
+
     def absolute_path(self, arg, default):
         if arg is not None and os.path.isabs(arg):
             return arg
@@ -264,6 +288,10 @@ class QubesVm(object):
             os.symlink (new_label.icon_path, self.icon_path)
             subprocess.call(['sudo', 'xdg-icon-resource', 'forceupdate'])
 
+        # fire hooks
+        for hook in self.hooks_label_setter:
+            hook(self, new_label)
+
     @property
     def netvm(self):
         return self._netvm
@@ -272,6 +300,9 @@ class QubesVm(object):
     @netvm.setter
     def netvm(self, new_netvm):
         self._set_netvm(new_netvm)
+        # fire hooks
+        for hook in self.hooks_netvm_setter:
+            hook(self, new_netvm)
 
     def _set_netvm(self, new_netvm):
         if self.is_running() and new_netvm is not None and not new_netvm.is_running():
@@ -375,6 +406,10 @@ class QubesVm(object):
     def pre_rename(self, new_name):
         self.remove_appmenus()
 
+        # fire hooks
+        for hook in self.hooks_pre_rename:
+            hook(self, new_name)
+
     def set_name(self, name):
         if self.is_running():
             raise QubesException("Cannot change name of running VM!")
@@ -413,6 +448,10 @@ class QubesVm(object):
     def post_rename(self, old_name):
         self.create_appmenus(verbose=False)
 
+        # fire hooks
+        for hook in self.hooks_post_rename:
+            hook(self, old_name)
+
     def is_template(self):
         return False
 
@@ -775,6 +814,10 @@ class QubesVm(object):
         xs.set_permissions('', '{0}/qubes-usb-devices'.format(domain_path),
                 [{ 'dom': xid }])
 
+        # fire hooks
+        for hook in self.hooks_create_xenstore_entries:
+            hook(self, xid=xid)
+
     def get_rootdev(self, source_template=None):
         if self.template:
             return "'script:snapshot:{dir}/root.img:{dir}/root-cow.img,xvda,r',".format(dir=self.template.dir_path)
@@ -831,6 +874,10 @@ class QubesVm(object):
                 print >> sys.stderr, "--> Debug mode: adding 'earlyprintk=xen' to kernel opts"
                 args['kernelopts'] += ' earlyprintk=xen'
 
+        # fire hooks
+        for hook in self.hooks_get_config_params:
+            args = hook(self, args)
+
         return args
 
     @property
@@ -948,12 +995,19 @@ class QubesVm(object):
                 subprocess.check_call ([system_path["qubes_appmenu_create_cmd"], "none", self.name, vmtype])
         except subprocess.CalledProcessError:
             print >> sys.stderr, "Ooops, there was a problem creating appmenus for {0} VM!".format (self.name)
+        # fire hooks
+        for hook in self.hooks_create_on_disk:
+            hook(self, verbose, source_template=source_template)
 
     def get_clone_attrs(self):
-        return ['kernel', 'uses_default_kernel', 'netvm', 'uses_default_netvm', \
+        attrs = ['kernel', 'uses_default_kernel', 'netvm', 'uses_default_netvm', \
             'memory', 'maxmem', 'kernelopts', 'uses_default_kernelopts', 'services', 'vcpus', \
             '_mac', 'pcidevs', 'include_in_backups', '_label']
 
+        # fire hooks
+        for hook in self.hooks_get_clone_attrs:
+            attrs = hook(self, attrs)
+
     def clone_attrs(self, src_vm):
         self._do_not_reset_firewall = True
         for prop in self.get_clone_attrs():
@@ -1019,6 +1073,10 @@ class QubesVm(object):
         # Create appmenus
         self.create_appmenus(verbose=verbose)
 
+        # fire hooks
+        for hook in self.hooks_clone_disk_files:
+            hook(self, verbose, src_vm)
+
     def remove_appmenus(self):
         vmtype = None
         if self.is_netvm():
@@ -1060,6 +1118,11 @@ class QubesVm(object):
             raise QubesException (
                 "VM kernel modules image does not exists: {0}".\
                 format(os.path.join(self.kernels_dir, 'modules.img')))
+
+        # fire hooks
+        for hook in self.hooks_verify_files:
+            hook(self)
+
         return True
 
     def reset_volatile_storage(self, source_template = None, verbose = False):
@@ -1097,6 +1160,10 @@ class QubesVm(object):
         if dry_run:
             return
 
+        # fire hooks
+        for hook in self.hooks_remove_from_disk:
+            hook(self)
+
         shutil.rmtree (self.dir_path)
 
     def write_firewall_conf(self, conf):
@@ -1423,6 +1490,11 @@ class QubesVm(object):
             if vm.is_proxyvm() and vm.is_running():
                 vm.write_iptables_xenstore_entry()
 
+        # fire hooks
+        for hook in self.hooks_start:
+            hook(self, verbose = verbose, preparing_dvm =  preparing_dvm,
+                    start_guid = start_guid, notify_function = notify_function)
+
         if verbose:
             print >> sys.stderr, "--> Starting the VM..."
         xc.domain_unpause(xid)

dom0/core-modules/01QubesHVm.py

@@ -134,6 +134,10 @@ class QubesHVm(QubesVm):
         f_private.truncate(defaults["hvm_private_img_size"])
         f_root.close()
 
+        # fire hooks
+        for hook in self.hooks_create_on_disk:
+            hook(self, verbose, source_template=source_template)
+
     def remove_from_disk(self):
         if dry_run:
             return
@@ -218,6 +222,10 @@ class QubesHVm(QubesVm):
             f_private.truncate(defaults["hvm_private_img_size"])
             f_private.close()
 
+        # fire hooks
+        for hook in self.hooks_verify_files:
+            hook(self)
+
         return True
 
     def reset_volatile_storage(self, **kwargs):