Fix response to circular symlinks with Python v3.13

CHANGES/8565.bugfix.rst

@@ -0,0 +1 @@
+Fixed server checks for circular symbolic links to be compatible with Python 3.13 -- by :user:`steverep`.

aiohttp/web_fileresponse.py

@@ -188,7 +188,9 @@ async def prepare(self, request: "BaseRequest") -> Optional[AbstractStreamWriter
             file_path, st, file_encoding = await loop.run_in_executor(
                 None, self._get_file_path_stat_encoding, accept_encoding
             )
-        except FileNotFoundError:
+        except OSError:
+            # Most likely to be FileNotFoundError or OSError for circular
+            # symlinks in python >= 3.13, so respond with 404.
             self.set_status(HTTPNotFound.status_code)
             return await super().prepare(request)
 

aiohttp/web_urldispatcher.py

@@ -77,9 +77,9 @@
     BaseDict = dict
 
 CIRCULAR_SYMLINK_ERROR = (
-    OSError
+    (OSError,)
     if sys.version_info < (3, 10) and sys.platform.startswith("win32")
-    else RuntimeError
+    else (RuntimeError,) if sys.version_info < (3, 13) else ()
 )
 
 YARL_VERSION: Final[Tuple[int, ...]] = tuple(map(int, yarl_version.split(".")[:2]))
@@ -672,8 +672,9 @@ def _resolve_path_to_response(self, unresolved_path: Path) -> StreamResponse:
             else:
                 file_path = unresolved_path.resolve()
                 file_path.relative_to(self._directory)
-        except (ValueError, CIRCULAR_SYMLINK_ERROR) as error:
-            # ValueError for relative check; RuntimeError for circular symlink.
+        except (ValueError, *CIRCULAR_SYMLINK_ERROR) as error:
+            # ValueError is raised for the relative check. Circular symlinks
+            # raise here on resolving for python < 3.13.
             raise HTTPNotFound() from error
 
         # if path is a directory, return the contents if permitted. Note the