# -*- coding: utf-8 -*-
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"""
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werkzeug.filesystem
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~~~~~~~~~~~~~~~~~~~
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Various utilities for the local filesystem.
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:copyright: (c) 2015 by the Werkzeug Team, see AUTHORS for more details.
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:license: BSD, see LICENSE for more details.
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"""
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import codecs
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import sys
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import warnings
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# We do not trust traditional unixes.
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has_likely_buggy_unicode_filesystem = \
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sys.platform.startswith('linux') or 'bsd' in sys.platform
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def _is_ascii_encoding(encoding):
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"""
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Given an encoding this figures out if the encoding is actually ASCII (which
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is something we don't actually want in most cases). This is necessary
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because ASCII comes under many names such as ANSI_X3.4-1968.
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"""
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if encoding is None:
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return False
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try:
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return codecs.lookup(encoding).name == 'ascii'
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except LookupError:
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return False
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class BrokenFilesystemWarning(RuntimeWarning, UnicodeWarning):
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'''The warning used by Werkzeug to signal a broken filesystem. Will only be
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used once per runtime.'''
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_warned_about_filesystem_encoding = False
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def get_filesystem_encoding():
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"""
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Returns the filesystem encoding that should be used. Note that this is
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different from the Python understanding of the filesystem encoding which
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might be deeply flawed. Do not use this value against Python's unicode APIs
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because it might be different. See :ref:`filesystem-encoding` for the exact
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behavior.
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The concept of a filesystem encoding in generally is not something you
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should rely on. As such if you ever need to use this function except for
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writing wrapper code reconsider.
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"""
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global _warned_about_filesystem_encoding
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rv = sys.getfilesystemencoding()
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if has_likely_buggy_unicode_filesystem and not rv \
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or _is_ascii_encoding(rv):
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if not _warned_about_filesystem_encoding:
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warnings.warn(
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'Detected a misconfigured UNIX filesystem: Will use UTF-8 as '
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'filesystem encoding instead of {0!r}'.format(rv),
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BrokenFilesystemWarning)
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_warned_about_filesystem_encoding = True
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return 'utf-8'
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return rv
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