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# -*- coding: utf-8 -*-
# Copyright (C) 2010, 2011, 2012 Sebastian Wiesner <lunaryorn@gmail.com>
# This library is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation; either version 2.1 of the License, or (at your
# option) any later version.
# This library is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
# for more details.
# You should have received a copy of the GNU Lesser General Public License
# along with this library; if not, write to the Free Software Foundation,
# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
"""
pyudev._util
============
Internal utilities
.. moduleauthor:: Sebastian Wiesner <lunaryorn@gmail.com>
"""
from __future__ import (print_function, division, unicode_literals,
absolute_import)
import os
import sys
import stat
from pyudev._libudev import libudev
if sys.version_info[0] == 2:
text_type = unicode
else:
text_type = str
def ensure_byte_string(value):
"""
Return the given ``value`` as bytestring.
If the given ``value`` is not a byte string, but a real unicode string, it
is encoded with the filesystem encoding (as in
:func:`sys.getfilesystemencoding()`).
"""
if not isinstance(value, bytes):
value = value.encode(sys.getfilesystemencoding())
return value
def ensure_unicode_string(value):
"""
Return the given ``value`` as unicode string.
If the given ``value`` is not a unicode string, but a byte string, it is
decoded with the filesystem encoding (as in
:func:`sys.getfilesystemencoding()`).
"""
if not isinstance(value, text_type):
value = value.decode(sys.getfilesystemencoding())
return value
def property_value_to_bytes(value):
"""
Return a byte string, which represents the given ``value`` in a way
suitable as raw value of an udev property.
If ``value`` is a boolean object, it is converted to ``'1'`` or ``'0'``,
depending on whether ``value`` is ``True`` or ``False``. If ``value`` is a
byte string already, it is returned unchanged. Anything else is simply
converted to a unicode string, and then passed to
:func:`ensure_byte_string`.
"""
# udev represents boolean values as 1 or 0, therefore an explicit
# conversion to int is required for boolean values
if isinstance(value, bool):
value = int(value)
if isinstance(value, bytes):
return value
else:
return ensure_byte_string(text_type(value))
def string_to_bool(value):
"""
Convert the given unicode string ``value`` to a boolean object.
If ``value`` is ``'1'``, ``True`` is returned. If ``value`` is ``'0'``,
``False`` is returned. Any other value raises a
:exc:`~exceptions.ValueError`.
"""
if value not in ('1', '0'):
raise ValueError('Not a boolean value: {0!r}'.format(value))
return value == '1'
def udev_list_iterate(entry):
"""
Iteration helper for udev list entry objects.
Yield a tuple ``(name, value)``. ``name`` and ``value`` are bytestrings
containing the name and the value of the list entry. The exact contents
depend on the list iterated over.
"""
while entry:
name = libudev.udev_list_entry_get_name(entry)
value = libudev.udev_list_entry_get_value(entry)
yield (name, value)
entry = libudev.udev_list_entry_get_next(entry)
# for the sake of readability
_is_char_device = stat.S_ISCHR
_is_block_device = stat.S_ISBLK
def get_device_type(filename):
"""
Get the device type of a device file.
``filename`` is a string containing the path of a device file.
Return ``'char'`` if ``filename`` is a character device, or ``'block'`` if
``filename`` is a block device. Raise :exc:`~exceptions.ValueError` if
``filename`` is no device file at all. Raise
:exc:`~exceptions.EnvironmentError` if ``filename`` does not exist or if
its metadata was inaccessible.
.. versionadded:: 0.15
"""
mode = os.stat(filename).st_mode
if _is_char_device(mode):
return 'char'
elif _is_block_device(mode):
return 'block'
else:
raise ValueError('not a device file: {0!r}'.format(filename))
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