53 lines
1.7 KiB
Python
53 lines
1.7 KiB
Python
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from __future__ import annotations
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import os
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import stat
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import sys
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from errno import EACCES, EISDIR
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from pathlib import Path
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def raise_on_not_writable_file(filename: str) -> None:
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"""
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Raise an exception if attempting to open the file for writing would fail.
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This is done so files that will never be writable can be separated from files that are writable but currently
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locked.
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:param filename: file to check
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:raises OSError: as if the file was opened for writing.
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"""
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try: # use stat to do exists + can write to check without race condition
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file_stat = os.stat(filename) # noqa: PTH116
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except OSError:
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return # swallow does not exist or other errors
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if file_stat.st_mtime != 0: # if os.stat returns but modification is zero that's an invalid os.stat - ignore it
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if not (file_stat.st_mode & stat.S_IWUSR):
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raise PermissionError(EACCES, "Permission denied", filename)
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if stat.S_ISDIR(file_stat.st_mode):
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if sys.platform == "win32": # pragma: win32 cover
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# On Windows, this is PermissionError
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raise PermissionError(EACCES, "Permission denied", filename)
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else: # pragma: win32 no cover # noqa: RET506
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# On linux / macOS, this is IsADirectoryError
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raise IsADirectoryError(EISDIR, "Is a directory", filename)
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def ensure_directory_exists(filename: Path | str) -> None:
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"""
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Ensure the directory containing the file exists (create it if necessary).
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:param filename: file.
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"""
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Path(filename).parent.mkdir(parents=True, exist_ok=True)
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__all__ = [
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"ensure_directory_exists",
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"raise_on_not_writable_file",
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]
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