scripts/qom-fuse: add static type hints

Because fusepy does not have type hints, add some targeted warning
suppressions.

Namely, we need to allow subclassing something of an unknown type (in
qom_fuse.py), and we need to allow missing imports (recorded against
fuse itself) because mypy will be unable to import fusepy (even when
installed) as it has no types nor type stubs available.

Note: Until now, it was possible to run invocations like 'mypy qemu/'
from ./python and have that work. However, these targeted suppressions
require that you run 'mypy -p qemu/' instead. The correct, canonical
invocation is recorded in ./python/tests/mypy.sh and all of the various
CI invocations always use this correct form.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210603003719.1321369-16-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

2 files changed, 25 insertions, 9 deletions

diff --git a/python/setup.cfg b/python/setup.cfg
index c9b9445af9..ba8d29fd62 100644
--- a/python/setup.cfg
+++ b/python/setup.cfg
@@ -57,6 +57,14 @@ python_version = 3.6
 warn_unused_configs = True
 namespace_packages = True
 
+[mypy-qemu.qmp.qom_fuse]
+# fusepy has no type stubs:
+allow_subclassing_any = True
+
+[mypy-fuse]
+# fusepy has no type stubs:
+ignore_missing_imports = True
+
 [pylint.messages control]
 # Disable the message, report, category or checker with the given id(s). You
 # can either give multiple identifiers separated by comma (,) or put this
diff --git a/scripts/qmp/qom-fuse b/scripts/qmp/qom-fuse
index 0d11f73152..a5a7a304a3 100755
--- a/scripts/qmp/qom-fuse
+++ b/scripts/qmp/qom-fuse
@@ -38,7 +38,14 @@ from errno import ENOENT, EPERM
 import os
 import stat
 import sys
-from typing import Dict
+from typing import (
+    IO,
+    Dict,
+    Iterator,
+    Mapping,
+    Optional,
+    Union,
+)
 
 import fuse
 from fuse import FUSE, FuseOSError, Operations
@@ -83,7 +90,7 @@ class QOMFuse(QOMCommand, Operations):
         self.fuse = FUSE(self, self.mount, foreground=True)
         return 0
 
-    def get_ino(self, path):
+    def get_ino(self, path: str) -> int:
         """Get an inode number for a given QOM path."""
         if path in self.ino_map:
             return self.ino_map[path]
@@ -91,7 +98,7 @@ class QOMFuse(QOMCommand, Operations):
         self.ino_count += 1
         return self.ino_map[path]
 
-    def is_object(self, path):
+    def is_object(self, path: str) -> bool:
         """Is the given QOM path an object?"""
         try:
             self.qom_list(path)
@@ -99,7 +106,7 @@ class QOMFuse(QOMCommand, Operations):
         except QMPResponseError:
             return False
 
-    def is_property(self, path):
+    def is_property(self, path: str) -> bool:
         """Is the given QOM path a property?"""
         path, prop = path.rsplit('/', 1)
         if path == '':
@@ -112,7 +119,7 @@ class QOMFuse(QOMCommand, Operations):
         except QMPResponseError:
             return False
 
-    def is_link(self, path):
+    def is_link(self, path: str) -> bool:
         """Is the given QOM path a link?"""
         path, prop = path.rsplit('/', 1)
         if path == '':
@@ -125,7 +132,7 @@ class QOMFuse(QOMCommand, Operations):
         except QMPResponseError:
             return False
 
-    def read(self, path, size, offset, fh):
+    def read(self, path: str, size: int, offset: int, fh: IO[bytes]) -> bytes:
         if not self.is_property(path):
             raise FuseOSError(ENOENT)
 
@@ -143,7 +150,7 @@ class QOMFuse(QOMCommand, Operations):
 
         return bytes(data[offset:][:size], encoding='utf-8')
 
-    def readlink(self, path):
+    def readlink(self, path: str) -> Union[bool, str]:
         if not self.is_link(path):
             return False
         path, prop = path.rsplit('/', 1)
@@ -151,7 +158,8 @@ class QOMFuse(QOMCommand, Operations):
         return prefix + str(self.qmp.command('qom-get', path=path,
                                              property=prop))
 
-    def getattr(self, path, fh=None):
+    def getattr(self, path: str,
+                fh: Optional[IO[bytes]] = None) -> Mapping[str, object]:
         if self.is_link(path):
             value = {
                 'st_mode': 0o755 | stat.S_IFLNK,
@@ -195,7 +203,7 @@ class QOMFuse(QOMCommand, Operations):
             raise FuseOSError(ENOENT)
         return value
 
-    def readdir(self, path, fh):
+    def readdir(self, path: str, fh: IO[bytes]) -> Iterator[str]:
         yield '.'
         yield '..'
         for item in self.qom_list(path):