filesystem.py
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# -*- coding: utf-8 -*-
"""
werkzeug.filesystem
~~~~~~~~~~~~~~~~~~~
Various utilities for the local filesystem.
:copyright: 2007 Pallets
:license: BSD-3-Clause
"""
import codecs
import sys
import warnings
# We do not trust traditional unixes.
has_likely_buggy_unicode_filesystem = (
sys.platform.startswith("linux") or "bsd" in sys.platform
)
def _is_ascii_encoding(encoding):
"""Given an encoding this figures out if the encoding is actually ASCII (which
is something we don't actually want in most cases). This is necessary
because ASCII comes under many names such as ANSI_X3.4-1968.
"""
if encoding is None:
return False
try:
return codecs.lookup(encoding).name == "ascii"
except LookupError:
return False
class BrokenFilesystemWarning(RuntimeWarning, UnicodeWarning):
"""The warning used by Werkzeug to signal a broken filesystem. Will only be
used once per runtime."""
_warned_about_filesystem_encoding = False
def get_filesystem_encoding():
"""Returns the filesystem encoding that should be used. Note that this is
different from the Python understanding of the filesystem encoding which
might be deeply flawed. Do not use this value against Python's unicode APIs
because it might be different. See :ref:`filesystem-encoding` for the exact
behavior.
The concept of a filesystem encoding in generally is not something you
should rely on. As such if you ever need to use this function except for
writing wrapper code reconsider.
"""
global _warned_about_filesystem_encoding
rv = sys.getfilesystemencoding()
if has_likely_buggy_unicode_filesystem and not rv or _is_ascii_encoding(rv):
if not _warned_about_filesystem_encoding:
warnings.warn(
"Detected a misconfigured UNIX filesystem: Will use"
" UTF-8 as filesystem encoding instead of {0!r}".format(rv),
BrokenFilesystemWarning,
)
_warned_about_filesystem_encoding = True
return "utf-8"
return rv