config: Allow overriding target path in dropin config component

- To be used when configuration has to change based on the package version.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>

plinth/config.py

@@ -108,14 +108,12 @@ class DropinConfigs(app_module.FollowerComponent):
 
         return results
 
-    @staticmethod
-    def get_target_path(path):
+    def get_target_path(self, path):
         """Return Path object for a target path."""
-        target = pathlib.Path(DropinConfigs.ROOT)
-        target /= DropinConfigs.DROPIN_CONFIG_ROOT.lstrip('/')
+        target = pathlib.Path(self.ROOT)
+        target /= self.DROPIN_CONFIG_ROOT.lstrip('/')
         return target / path.lstrip('/')
 
-    @staticmethod
-    def get_etc_path(path):
+    def get_etc_path(self, path):
         """Return Path object for etc path."""
-        return pathlib.Path(DropinConfigs.ROOT) / path.lstrip('/')
+        return pathlib.Path(self.ROOT) / path.lstrip('/')

plinth/privileged/config.py

@@ -10,7 +10,7 @@ from plinth import module_loader
 from plinth.actions import privileged
 
 
-def _assert_managed_dropin_config(app_id: str, path: str):
+def _get_managed_dropin_config(app_id: str, path: str):
     """Check that this is a path managed by the specified app."""
     module_path = module_loader.get_module_import_path(app_id)
     module = importlib.import_module(module_path)
@@ -25,7 +25,7 @@ def _assert_managed_dropin_config(app_id: str, path: str):
         components = app.get_components_of_type(DropinConfigs)
         for component in components:
             if path in component.etc_paths:
-                return
+                return component
 
     raise AssertionError('Not a managed drop-in config')
 
@@ -37,10 +37,9 @@ def dropin_is_valid(app_id: str, path: str, copy_only: bool,
 
     Optionally, drop the link if it is invalid.
     """
-    _assert_managed_dropin_config(app_id, path)
-    from plinth.config import DropinConfigs
-    etc_path = DropinConfigs.get_etc_path(path)
-    target = DropinConfigs.get_target_path(path)
+    component = _get_managed_dropin_config(app_id, path)
+    etc_path = component.get_etc_path(path)
+    target = component.get_target_path(path)
     if etc_path.exists() or etc_path.is_symlink():
         if (not copy_only and etc_path.is_symlink()
                 and etc_path.readlink() == target):
@@ -59,10 +58,9 @@ def dropin_is_valid(app_id: str, path: str, copy_only: bool,
 @privileged
 def dropin_link(app_id: str, path: str, copy_only: bool):
     """Create a symlink from /etc/ to /usr/share/freedombox/etc."""
-    _assert_managed_dropin_config(app_id, path)
-    from plinth.config import DropinConfigs
-    target = DropinConfigs.get_target_path(path)
-    etc_path = DropinConfigs.get_etc_path(path)
+    component = _get_managed_dropin_config(app_id, path)
+    target = component.get_target_path(path)
+    etc_path = component.get_etc_path(path)
     etc_path.parent.mkdir(parents=True, exist_ok=True)
     if copy_only:
         shutil.copyfile(target, etc_path)
@@ -73,7 +71,6 @@ def dropin_link(app_id: str, path: str, copy_only: bool):
 @privileged
 def dropin_unlink(app_id: str, path: str, missing_ok: bool = False):
     """Remove a symlink in /etc/."""
-    _assert_managed_dropin_config(app_id, path)
-    from plinth.config import DropinConfigs
-    etc_path = DropinConfigs.get_etc_path(path)
+    component = _get_managed_dropin_config(app_id, path)
+    etc_path = component.get_etc_path(path)
     etc_path.unlink(missing_ok=missing_ok)

plinth/tests/test_config.py

@@ -31,9 +31,10 @@ def fixture_dropin_configs():
 
 
 @pytest.fixture(autouse=True)
-def fixture_assert_dropin_config():
+def fixture_assert_dropin_config(dropin_configs):
     """Mock asserting dropin config path."""
-    with patch('plinth.privileged.config._assert_managed_dropin_config'):
+    with patch('plinth.privileged.config._get_managed_dropin_config') as mock:
+        mock.return_value = dropin_configs
         yield
 
 
@@ -95,7 +96,7 @@ def test_dropin_configs_enable_disable_symlinks(dropin_configs, tmp_path):
 
         # Enable when a file already exists
         dropin_configs.disable()
-        etc_path = DropinConfigs.get_etc_path('/etc/test/path1')
+        etc_path = dropin_configs.get_etc_path('/etc/test/path1')
         etc_path.touch()
         dropin_configs.enable()
         _assert_symlinks(dropin_configs, tmp_path, should_exist=True)
@@ -108,7 +109,7 @@ def test_dropin_configs_enable_disable_symlinks(dropin_configs, tmp_path):
 
         # When symlink already exists to correct location
         dropin_configs.disable()
-        target_path = DropinConfigs.get_target_path('/etc/test/path1')
+        target_path = dropin_configs.get_target_path('/etc/test/path1')
         etc_path.symlink_to(target_path)
         dropin_configs.enable()
         _assert_symlinks(dropin_configs, tmp_path, should_exist=True)
@@ -119,7 +120,7 @@ def test_dropin_configs_enable_disable_copy_only(dropin_configs, tmp_path):
     with patch('plinth.config.DropinConfigs.ROOT', new=tmp_path):
         dropin_configs.copy_only = True
         for path in ['/etc/test/path1', '/etc/path2']:
-            target = DropinConfigs.get_target_path(path)
+            target = dropin_configs.get_target_path(path)
             target.parent.mkdir(parents=True, exist_ok=True)
             target.write_text('test-config-content')
 
@@ -135,7 +136,7 @@ def test_dropin_configs_enable_disable_copy_only(dropin_configs, tmp_path):
 
         # Enable when a file already exists with wrong content
         dropin_configs.disable()
-        etc_path = DropinConfigs.get_etc_path('/etc/test/path1')
+        etc_path = dropin_configs.get_etc_path('/etc/test/path1')
         etc_path.write_text('x-invalid-content')
         dropin_configs.enable()
         _assert_symlinks(dropin_configs, tmp_path, should_exist=True,
@@ -182,7 +183,7 @@ def test_dropin_config_diagnose_symlinks(dropin_configs, tmp_path):
 
         # A file exists instead of symlink
         dropin_configs.disable()
-        etc_path = DropinConfigs.get_etc_path('/etc/test/path1')
+        etc_path = dropin_configs.get_etc_path('/etc/test/path1')
         etc_path.touch()
         results = dropin_configs.diagnose()
         assert results[0].result == 'failed'
@@ -204,7 +205,7 @@ def test_dropin_config_diagnose_copy_only(dropin_configs, tmp_path):
     with patch('plinth.config.DropinConfigs.ROOT', new=tmp_path):
         dropin_configs.copy_only = True
         for path in ['/etc/test/path1', '/etc/path2']:
-            target = DropinConfigs.get_target_path(path)
+            target = dropin_configs.get_target_path(path)
             target.parent.mkdir(parents=True, exist_ok=True)
             target.write_text('test-config-content')
 
@@ -221,7 +222,7 @@ def test_dropin_config_diagnose_copy_only(dropin_configs, tmp_path):
 
         # A symlink exists instead of a copied file
         dropin_configs.disable()
-        etc_path = DropinConfigs.get_etc_path('/etc/test/path1')
+        etc_path = dropin_configs.get_etc_path('/etc/test/path1')
         etc_path.symlink_to('/blah')
         results = dropin_configs.diagnose()
         assert results[0].result == 'failed'