Fix mypy errors

src/allmydata/grid_manager.py

@@ -11,6 +11,7 @@ from typing import (
     Optional,
     Union,
     List,
+    IO
 )
 
 from twisted.python.filepath import FilePath
@@ -178,6 +179,7 @@ def load_grid_manager(config_path: Optional[FilePath]):
     :raises: ValueError if the confguration is invalid or IOError if
         expected files can't be opened.
     """
+    config_file: Union[IO[bytes], IO[str]]
     if config_path is None:
         config_file = sys.stdin
     else:

src/allmydata/node.py

@@ -200,14 +200,14 @@ def read_config(basedir, portnumfile, generated_files: Iterable = (), _valid_con
 
     config_path = FilePath(basedir).child("tahoe.cfg")
     try:
-        config_str = config_path.getContent()
+        config_bytes = config_path.getContent()
     except EnvironmentError as e:
         if e.errno != errno.ENOENT:
             raise
         # The file is missing, just create empty ConfigParser.
         config_str = u""
     else:
-        config_str = config_str.decode("utf-8-sig")
+        config_str = config_bytes.decode("utf-8-sig")
 
     return config_from_string(
         basedir,

src/allmydata/util/cputhreadpool.py

@@ -15,7 +15,7 @@ scheduler affinity or cgroups, but that's not the end of the world.
 """
 
 import os
-from typing import TypeVar, Callable
+from typing import TypeVar, Callable, cast
 from functools import partial
 import threading
 from typing_extensions import ParamSpec
@@ -24,8 +24,9 @@ from unittest import TestCase
 from twisted.python.threadpool import ThreadPool
 from twisted.internet.threads import deferToThreadPool
 from twisted.internet import reactor
+from twisted.internet.interfaces import IReactorFromThreads
 
-_CPU_THREAD_POOL = ThreadPool(minthreads=0, maxthreads=os.cpu_count(), name="TahoeCPU")
+_CPU_THREAD_POOL = ThreadPool(minthreads=0, maxthreads=os.cpu_count() or 1, name="TahoeCPU")
 if hasattr(threading, "_register_atexit"):
     # This is a private API present in Python 3.8 or later, specifically
     # designed for thread pool shutdown. Since it's private, it might go away
@@ -64,7 +65,7 @@ async def defer_to_thread(f: Callable[P, R], *args: P.args, **kwargs: P.kwargs)
         return f(*args, **kwargs)
 
     # deferToThreadPool has no type annotations...
-    result = await deferToThreadPool(reactor, _CPU_THREAD_POOL, f, *args, **kwargs)
+    result = await deferToThreadPool(cast(IReactorFromThreads, reactor), _CPU_THREAD_POOL, f, *args, **kwargs)
     return result
 
 

src/allmydata/web/common.py

@@ -874,6 +874,6 @@ def add_static_children(root: IResource):
     for child in static_dir.iterdir():
         child_path = child.name.encode("utf-8")
         root.putChild(child_path, static.File(
-            temporary_file_manager.enter_context(as_file(child))
+            str(temporary_file_manager.enter_context(as_file(child)))
         ))
     weakref.finalize(root, temporary_file_manager.close)