Infrastructure for custom backend support

backend/decky_loader/plugin/binary_plugin.py

@@ -0,0 +1,54 @@
+from asyncio import StreamReader, create_task, sleep, create_subprocess_exec
+from asyncio.subprocess import Process
+from subprocess import PIPE
+
+from .sandboxed_plugin import SandboxedPlugin
+from ..localplatform.localsocket import LocalSocket
+from ..customtypes import UserType
+
+from typing import Dict, List
+
+class BinaryPlugin(SandboxedPlugin):
+    def __init__(self,
+                 socket: LocalSocket,
+                 name: str,
+                 flags: List[str],
+                 file: str,
+                 plugin_directory: str,
+                 plugin_path: str,
+                 version: str | None,
+                 author: str,
+                 env: Dict[str, str]) -> None:
+        super().__init__(socket, name, flags, file, plugin_directory, plugin_path, version, author, env)
+        self.process: Process
+
+    def start(self):
+        create_task(self._start())
+
+    async def stop(self):
+        self.process.terminate()
+        while not self.process.returncode:
+            await sleep(0)
+
+    async def _start(self):
+        self.env["DECKY_SOCKET"] = self.socket.socket_addr
+        user_type = UserType.ROOT.value if "root" in self.flags else UserType.HOST_USER.value
+        self.process = await create_subprocess_exec(self.file,
+                             env=self.env,
+                             user=user_type,
+                             group=user_type,
+                             stdout=PIPE,
+                             stderr=PIPE)
+        assert self.process.stderr and self.process.stdout
+        create_task(self._stream_watcher(self.process.stdout, False))
+        create_task(self._stream_watcher(self.process.stderr, True))
+        
+    async def _stream_watcher(self, stream: StreamReader, is_err: bool):
+        async for line in stream:
+            line = line.decode("utf-8")
+            if not line.strip():
+                continue
+            if is_err:
+                self.log.error(line)
+            else:
+                self.log.info(line)