diff --git a/pre_commit/error_handler.py b/pre_commit/error_handler.py index b2321ae0..13d78cbb 100644 --- a/pre_commit/error_handler.py +++ b/pre_commit/error_handler.py @@ -18,10 +18,17 @@ class FatalError(RuntimeError): def _log_and_exit(msg: str, exc: BaseException, formatted: str) -> None: error_msg = f'{msg}: {type(exc).__name__}: '.encode() + force_bytes(exc) output.write_line_b(error_msg) - log_path = os.path.join(Store().directory, 'pre-commit.log') - output.write_line(f'Check the log at {log_path}') - with open(log_path, 'wb') as log: + storedir = Store().directory + log_path = os.path.join(storedir, 'pre-commit.log') + with contextlib.ExitStack() as ctx: + if os.access(storedir, os.W_OK): + output.write_line(f'Check the log at {log_path}') + log = ctx.enter_context(open(log_path, 'wb')) + else: # pragma: win32 no cover + output.write_line(f'Failed to write to log at {log_path}') + log = sys.stdout.buffer + _log_line = functools.partial(output.write_line, stream=log) _log_line_b = functools.partial(output.write_line_b, stream=log) diff --git a/tests/error_handler_test.py b/tests/error_handler_test.py index 833bb8f8..d066e572 100644 --- a/tests/error_handler_test.py +++ b/tests/error_handler_test.py @@ -1,13 +1,16 @@ import os.path import re +import stat import sys from unittest import mock import pytest from pre_commit import error_handler +from pre_commit.store import Store from pre_commit.util import CalledProcessError from testing.util import cmd_output_mocked_pre_commit_home +from testing.util import xfailif_windows @pytest.fixture @@ -168,3 +171,29 @@ def test_error_handler_no_tty(tempdir_factory): out_lines = out.splitlines() assert out_lines[-2] == 'An unexpected error has occurred: ValueError: ☃' assert out_lines[-1] == f'Check the log at {log_file}' + + +@xfailif_windows # pragma: win32 no cover +def test_error_handler_read_only_filesystem(mock_store_dir, cap_out, capsys): + # a better scenario would be if even the Store crash would be handled + # but realistically we're only targetting systems where the Store has + # already been set up + Store() + + write = (stat.S_IWGRP | stat.S_IWOTH | stat.S_IWUSR) + os.chmod(mock_store_dir, os.stat(mock_store_dir).st_mode & ~write) + + with pytest.raises(SystemExit): + with error_handler.error_handler(): + raise ValueError('ohai') + + output = cap_out.get() + assert output.startswith( + 'An unexpected error has occurred: ValueError: ohai\n' + 'Failed to write to log at ', + ) + + # our cap_out mock is imperfect so the rest of the output goes to capsys + out, _ = capsys.readouterr() + # the things that normally go to the log file will end up here + assert '### version information' in out