Root plugins (#35)

* root plugins

plugins can now specify if they want their methods to be ran as root. this is done via the multiprocess module. method calls are delegated to a separate process that is then down-privileged by default to user 1000, so the loader can safely be ran as root

except it isn't really safe because the plugin is imported as root anyway

* working implementation

- follows the new plugin format with the plugin.json file
- plugins are loaded in their own isolated process along with their own event loop and unix socket server for calling methods
- private methods are now prepended with _ instead of __

* converted format to f-strings

plugin_loader/plugin.py

@@ -0,0 +1,88 @@
+from importlib.util import spec_from_file_location, module_from_spec
+from asyncio import get_event_loop, start_unix_server, open_unix_connection, sleep, Lock
+from os import path, setuid
+from json import loads, dumps, load
+from concurrent.futures import ProcessPoolExecutor
+from time import time
+
+class PluginWrapper:
+    def __init__(self, file, plugin_directory, plugin_path) -> None:
+        self.file = file
+        self.plugin_directory = plugin_directory
+        self.reader = None
+        self.writer = None
+        self.socket_addr = f"/tmp/plugin_socket_{time()}"
+        self.method_call_lock = Lock()
+
+        json = load(open(path.join(plugin_path, plugin_directory, "plugin.json"), "r"))
+
+        self.name = json["name"]
+        self.author = json["author"]
+        self.main_view_html = json["main_view_html"]
+        self.tile_view_html = json["tile_view_html"] if "tile_view_html" in json else ""
+        self.flags = json["flags"]
+
+    def _init(self):
+        setuid(0 if "root" in self.flags else 1000)
+        spec = spec_from_file_location("_", self.file)
+        module = module_from_spec(spec)
+        spec.loader.exec_module(module)
+        self.Plugin = module.Plugin
+
+        if hasattr(self.Plugin, "_main"):
+            get_event_loop().create_task(self.Plugin._main(self.Plugin))
+        get_event_loop().create_task(self._setup_socket())
+        get_event_loop().run_forever()
+
+    async def _setup_socket(self):
+        self.socket = await start_unix_server(self._listen_for_method_call, path=self.socket_addr)
+
+    async def _listen_for_method_call(self, reader, writer):
+        while True:
+            data = loads((await reader.readline()).decode("utf-8"))
+            if "stop" in data:
+                return get_event_loop().stop()
+            d = {"res": None, "success": True}
+            try:
+                d["res"] = await getattr(self.Plugin, data["method"])(self.Plugin, **data["args"])
+            except Exception as e:
+                d["res"] = str(e)
+                d["success"] = False
+            finally:
+                writer.write((dumps(d)+"\n").encode("utf-8"))
+                await writer.drain()
+
+    async def _open_socket_if_not_exists(self):
+        if not self.reader:
+            while True:
+                try:
+                    self.reader, self.writer = await open_unix_connection(self.socket_addr)
+                    break
+                except:
+                    await sleep(0)
+
+    def start(self, loop):
+        executor = ProcessPoolExecutor()
+        loop.run_in_executor(
+            executor,
+            self._init
+        )
+        return self
+
+    def stop(self, loop):
+        async def _(self):
+            await self._open_socket_if_not_exists()
+            self.writer.write((dumps({"stop": True})+"\n").encode("utf-8"))
+            await self.writer.drain()
+        loop.create_task(_(self))
+
+    async def execute_method(self, method_name, kwargs):
+        async with self.method_call_lock:
+            await self._open_socket_if_not_exists()
+            self.writer.write(
+                (dumps({"method": method_name, "args": kwargs})+"\n").encode("utf-8"))
+            await self.writer.drain()
+            res = loads((await self.reader.readline()).decode("utf-8"))
+            if not res["success"]:
+                raise Exception(res["res"])
+            return res["res"]