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fix: raise warning instead of error when chmod is not allowed #2375

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Merged
merged 1 commit into from
Oct 27, 2025
Merged

fix: raise warning instead of error when chmod is not allowed #2375

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16 changes: 14 additions & 2 deletions copier/_main.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,10 @@

import os
import platform
import stat
import subprocess
import sys
import warnings
from collections.abc import Iterable, Mapping, Sequence
from contextlib import suppress
from contextvars import ContextVar
Expand Down Expand Up @@ -733,7 +735,7 @@ def _render_template(self) -> None:
else:
self._render_file(src_relpath, dst_relpath, extra_context=ctx or {})

def _render_file(
def _render_file( # noqa: C901
self,
src_relpath: Path,
dst_relpath: Path,
Expand Down Expand Up @@ -785,7 +787,17 @@ def _render_file(
# replace a symlink with a file we have to unlink it first
dst_abspath.unlink()
dst_abspath.write_bytes(new_content)
dst_abspath.chmod(src_mode)
if (dst_mode := dst_abspath.stat().st_mode) != src_mode:
try:
dst_abspath.chmod(src_mode)
except PermissionError:
# In some filesystems (e.g., gcsfuse), `chmod` is not allowed,
# so we suppress the `PermissionError` here.
warnings.warn(
f"Path permissions for {dst_abspath} cannot be changed from "
f"{stat.filemode(dst_mode)} to {stat.filemode(src_mode)}",
stacklevel=2,
)

def _render_symlink(self, src_relpath: Path, dst_relpath: Path) -> None:
"""Render one symlink.
Expand Down
42 changes: 42 additions & 0 deletions tests/test_copy.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
from textwrap import dedent, indent
from time import sleep
from typing import Any
from unittest import mock

import pytest
import yaml
Expand Down Expand Up @@ -1384,3 +1385,44 @@ def test_skipped_question_with_unset_default_value(
)
copier.run_copy(str(src), dst, defaults=True)
assert (dst / "output.txt").read_text("utf-8") == "<undefined>"


def test_warn_if_chmod_raises_permission_error(
tmp_path_factory: pytest.TempPathFactory,
) -> None:
"""Test that a warning is raised when `chmod` raises a `PermissionError`.

Changing path permissions is not allowed in some filesystems like gcsfuse. In this
case, Copier should not fail but suppress the error and raise a warning.
"""
src, dst = map(tmp_path_factory.mktemp, ("src", "dst"))
build_file_tree(
{
src / "test.txt": "foo",
dst / "test.txt": "bar",
}
)

# Ensure that the source and destination files have different permissions, so
# Copier will want to change the permissions of the destination file to those of
# the source file.
(src / "test.txt").chmod(0o400)
(dst / "test.txt").chmod(0o600)

dst_file_mode = (dst / "test.txt").stat().st_mode

def mocked_chmod(self: Path, mode: int) -> None:
if self == dst / "test.txt":
raise PermissionError("Operation not permitted")
return chmod(self, mode)

chmod = Path.chmod

with (
mock.patch.object(Path, "chmod", new=mocked_chmod),
pytest.warns(UserWarning, match=r"^Path permissions for .+? cannot be changed"),
):
copier.run_copy(str(src), dst, overwrite=True)

assert (dst / "test.txt").stat().st_mode == dst_file_mode
assert (dst / "test.txt").read_text("utf-8") == "foo"
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