fix(#565): Handle OSError

src/mdformat/_cli.py

@@ -327,6 +327,7 @@ class InvalidPath(Exception):
     """Exception raised when a path does not exist."""
 
     def __init__(self, path: Path):
+        super().__init__(f'File "{path}" does not exist.')
         self.path = path
 
 

src/mdformat/_conf.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from collections.abc import Mapping
+from contextlib import suppress
 import functools
 from pathlib import Path
 from types import MappingProxyType
@@ -35,7 +36,10 @@ class InvalidConfError(Exception):
 @functools.lru_cache
 def read_toml_opts(conf_dir: Path) -> tuple[Mapping, Path | None]:
     conf_path = conf_dir / ".mdformat.toml"
-    if not conf_path.is_file():
+    is_file = False
+    with suppress(OSError):
+        is_file = conf_path.is_file()
+    if not is_file:
         parent_dir = conf_dir.parent
         if conf_dir == parent_dir:
             return {}, None

tests/test_config_file.py

@@ -1,3 +1,4 @@
+from pathlib import Path
 import sys
 from unittest import mock
 
@@ -168,3 +169,24 @@ def test_conf_no_validate(tmp_path):
 
         assert run((str(file_path),), cache_toml=False) == 0
         assert file_path.read_text() == "1? ordered\n"
+
+
+def test_conf_search_with_oserror(tmp_path):
+    config_path = tmp_path / ".mdformat.toml"
+    config_path.write_text("wrap = 'no'")
+
+    subdir_path = tmp_path / "subdir"
+    subdir_path.mkdir()
+    file_path = subdir_path / "test_markdown.md"
+    file_path.write_text("remove\nthis\nwrap")
+
+    original_is_file = Path.is_file
+
+    def mock_is_file(self):
+        if str(self).endswith("subdir/.mdformat.toml"):
+            raise OSError(5, "Input/output error")
+        return original_is_file(self)
+
+    with mock.patch("pathlib.Path.is_file", new=mock_is_file):
+        assert run((str(file_path),), cache_toml=False) == 0
+        assert file_path.read_text() == "remove this wrap\n"