File: core.py

package info (click to toggle)
pyudev 0.21.0-1
  • links: PTS, VCS
  • area: main
  • in suites: buster, sid, stretch
  • size: 716 kB
  • ctags: 870
  • sloc: python: 4,122; makefile: 16
file content (394 lines) | stat: -rw-r--r-- 13,435 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
# -*- coding: utf-8 -*-
# Copyright (C) 2010, 2011 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.core
    ===========

    Core types and functions of :mod:`pyudev`.

    .. moduleauthor::  Sebastian Wiesner  <lunaryorn@gmail.com>
"""


from __future__ import (print_function, division, unicode_literals,
                        absolute_import)

from pyudev.device import Devices
from pyudev.device._errors import DeviceNotFoundAtPathError
from pyudev._ctypeslib.libudev import ERROR_CHECKERS
from pyudev._ctypeslib.libudev import SIGNATURES
from pyudev._ctypeslib.utils import load_ctypes_library

from pyudev._util import ensure_byte_string
from pyudev._util import ensure_unicode_string
from pyudev._util import property_value_to_bytes
from pyudev._util import udev_list_iterate


class Context(object):
    """
    A device database connection.

    This class represents a connection to the udev device database, and is
    really *the* central object to access udev.  You need an instance of this
    class for almost anything else in pyudev.

    This class itself gives access to various udev configuration data (e.g.
    :attr:`sys_path`, :attr:`device_path`), and provides device enumeration
    (:meth:`list_devices()`).

    Instances of this class can directly be given as ``udev *`` to functions
    wrapped through :mod:`ctypes`.
    """

    def __init__(self):
        """
        Create a new context.
        """
        self._libudev = load_ctypes_library('libudev.so.1', SIGNATURES, ERROR_CHECKERS)
        self._as_parameter_ = self._libudev.udev_new()

    def __del__(self):
        self._libudev.udev_unref(self)

    @property
    def sys_path(self):
        """
        The ``sysfs`` mount point defaulting to ``/sys'`` as unicode string.
        """
        if hasattr(self._libudev, 'udev_get_sys_path'):
            return ensure_unicode_string(self._libudev.udev_get_sys_path(self))
        else:
            # Fixed path since udev 183
            return '/sys'

    @property
    def device_path(self):
        """
        The device directory path defaulting to ``/dev`` as unicode string.
        """
        if hasattr(self._libudev, 'udev_get_dev_path'):
            return ensure_unicode_string(self._libudev.udev_get_dev_path(self))
        else:
            # Fixed path since udev 183
            return '/dev'

    @property
    def run_path(self):
        """
        The run runtime directory path defaulting to ``/run`` as unicode
        string.

        .. udevversion:: 167

        .. versionadded:: 0.10
        """
        if hasattr(self._libudev, 'udev_get_run_path'):
            return ensure_unicode_string(self._libudev.udev_get_run_path(self))
        else:
            return '/run/udev'

    @property
    def log_priority(self):
        """
        The logging priority of the interal logging facitility of udev as
        integer with a standard :mod:`syslog` priority.  Assign to this
        property to change the logging priority.

        UDev uses the standard :mod:`syslog` priorities.  Constants for these
        priorities are defined in the :mod:`syslog` module in the standard
        library:

        >>> import syslog
        >>> context = pyudev.Context()
        >>> context.log_priority = syslog.LOG_DEBUG

        .. versionadded:: 0.9
        """
        return self._libudev.udev_get_log_priority(self)

    @log_priority.setter
    def log_priority(self, value):
        """
        Set the log priority.

        :param int value: the log priority.
        """
        self._libudev.udev_set_log_priority(self, value)

    def list_devices(self, **kwargs):
        """
        List all available devices.

        The arguments of this method are the same as for
        :meth:`Enumerator.match()`.  In fact, the arguments are simply passed
        straight to method :meth:`~Enumerator.match()`.

        This function creates and returns an :class:`Enumerator` object,
        that can be used to filter the list of devices, and eventually
        retrieve :class:`Device` objects representing matching devices.

        .. versionchanged:: 0.8
           Accept keyword arguments now for easy matching.
        """
        return Enumerator(self).match(**kwargs)


class Enumerator(object):
    """
    A filtered iterable of devices.

    To retrieve devices, simply iterate over an instance of this class.
    This operation yields :class:`Device` objects representing the available
    devices.

    Before iteration the device list can be filtered by subsystem or by
    property values using :meth:`match_subsystem` and
    :meth:`match_property`.  Multiple subsystem (property) filters are
    combined using a logical OR, filters of different types are combined
    using a logical AND.  The following filter for instance::

        devices.match_subsystem('block').match_property(
            'ID_TYPE', 'disk').match_property('DEVTYPE', 'disk')

    means the following::

        subsystem == 'block' and (ID_TYPE == 'disk' or DEVTYPE == 'disk')

    Once added, a filter cannot be removed anymore.  Create a new object
    instead.

    Instances of this class can directly be given as given ``udev_enumerate *``
    to functions wrapped through :mod:`ctypes`.
    """

    def __init__(self, context):
        """
        Create a new enumerator with the given ``context`` (a
        :class:`Context` instance).

        While you can create objects of this class directly, this is not
        recommended.  Call :method:`Context.list_devices()` instead.
        """
        if not isinstance(context, Context):
            raise TypeError('Invalid context object')
        self.context = context
        self._as_parameter_ = context._libudev.udev_enumerate_new(context)
        self._libudev = context._libudev

    def __del__(self):
        self._libudev.udev_enumerate_unref(self)

    def match(self, **kwargs):
        """
        Include devices according to the rules defined by the keyword
        arguments.  These keyword arguments are interpreted as follows:

        - The value for the keyword argument ``subsystem`` is forwarded to
          :meth:`match_subsystem()`.
        - The value for the keyword argument ``sys_name`` is forwared to
          :meth:`match_sys_name()`.
        - The value for the keyword argument ``tag`` is forwared to
          :meth:`match_tag()`.
        - The value for the keyword argument ``parent`` is forwared to
          :meth:`match_parent()`.
        - All other keyword arguments are forwareded one by one to
          :meth:`match_property()`.  The keyword argument itself is interpreted
          as property name, the value of the keyword argument as the property
          value.

        All keyword arguments are optional, calling this method without no
        arguments at all is simply a noop.

        Return the instance again.

        .. versionadded:: 0.8

        .. versionchanged:: 0.13
           Add ``parent`` keyword.
        """
        subsystem = kwargs.pop('subsystem', None)
        if subsystem is not None:
            self.match_subsystem(subsystem)
        sys_name = kwargs.pop('sys_name', None)
        if sys_name is not None:
            self.match_sys_name(sys_name)
        tag = kwargs.pop('tag', None)
        if tag is not None:
            self.match_tag(tag)
        parent = kwargs.pop('parent', None)
        if parent is not None:
            self.match_parent(parent)
        for prop, value in kwargs.items():
            self.match_property(prop, value)
        return self

    def match_subsystem(self, subsystem, nomatch=False):
        """
        Include all devices, which are part of the given ``subsystem``.

        ``subsystem`` is either a unicode string or a byte string, containing
        the name of the subsystem.  If ``nomatch`` is ``True`` (default is
        ``False``), the match is inverted:  A device is only included if it is
        *not* part of the given ``subsystem``.

        Note that, if a device has no subsystem, it is not included either
        with value of ``nomatch`` True or with value of ``nomatch`` False.

        Return the instance again.
        """
        match = self._libudev.udev_enumerate_add_nomatch_subsystem \
           if nomatch else self._libudev.udev_enumerate_add_match_subsystem
        match(self, ensure_byte_string(subsystem))
        return self

    def match_sys_name(self, sys_name):
        """
        Include all devices with the given name.

        ``sys_name`` is a byte or unicode string containing the device name.

        Return the instance again.

        .. versionadded:: 0.8
        """
        self._libudev.udev_enumerate_add_match_sysname(
            self, ensure_byte_string(sys_name))
        return self

    def match_property(self, prop, value):
        """
        Include all devices, whose ``prop`` has the given ``value``.

        ``prop`` is either a unicode string or a byte string, containing
        the name of the property to match.  ``value`` is a property value,
        being one of the following types:

        - :func:`int`
        - :func:`bool`
        - A byte string
        - Anything convertable to a unicode string (including a unicode string
          itself)

        Return the instance again.
        """
        self._libudev.udev_enumerate_add_match_property(
            self, ensure_byte_string(prop), property_value_to_bytes(value))
        return self

    def match_attribute(self, attribute, value, nomatch=False):
        """
        Include all devices, whose ``attribute`` has the given ``value``.

        ``attribute`` is either a unicode string or a byte string, containing
        the name of a sys attribute to match.  ``value`` is an attribute value,
        being one of the following types:

        - :func:`int`,
        - :func:`bool`
        - A byte string
        - Anything convertable to a unicode string (including a unicode string
          itself)

        If ``nomatch`` is ``True`` (default is ``False``), the match is
        inverted:  A device is include if the ``attribute`` does *not* match
        the given ``value``.

        .. note::

           If ``nomatch`` is ``True``, devices which do not have the given
           ``attribute`` at all are also included.  In other words, with
           ``nomatch=True`` the given ``attribute`` is *not* guaranteed to
           exist on all returned devices.

        Return the instance again.
        """
        match = (self._libudev.udev_enumerate_add_match_sysattr
                 if not nomatch else
                 self._libudev.udev_enumerate_add_nomatch_sysattr)
        match(self, ensure_byte_string(attribute),
              property_value_to_bytes(value))
        return self

    def match_tag(self, tag):
        """
        Include all devices, which have the given ``tag`` attached.

        ``tag`` is a byte or unicode string containing the tag name.

        Return the instance again.

        .. udevversion:: 154

        .. versionadded:: 0.6
        """
        self._libudev.udev_enumerate_add_match_tag(self, ensure_byte_string(tag))
        return self

    def match_is_initialized(self):
        """
        Include only devices, which are initialized.

        Initialized devices have properly set device node permissions and
        context, and are (in case of network devices) fully renamed.

        Currently this will not affect devices which do not have device nodes
        and are not network interfaces.

        Return the instance again.

        .. seealso:: :attr:`Device.is_initialized`

        .. udevversion:: 165

        .. versionadded:: 0.8
        """
        self._libudev.udev_enumerate_add_match_is_initialized(self)
        return self

    def match_parent(self, parent):
        """
        Include all devices on the subtree of the given ``parent`` device.

        The ``parent`` device itself is also included.

        ``parent`` is a :class:`~pyudev.Device`.

        Return the instance again.

        .. udevversion:: 172

        .. versionadded:: 0.13
        """
        self._libudev.udev_enumerate_add_match_parent(self, parent)
        return self

    def __iter__(self):
        """
        Iterate over all matching devices.

        Yield :class:`Device` objects.
        """
        self._libudev.udev_enumerate_scan_devices(self)
        entry = self._libudev.udev_enumerate_get_list_entry(self)
        for name, _ in udev_list_iterate(self._libudev, entry):
            try:
                yield Devices.from_sys_path(self.context, name)
            except DeviceNotFoundAtPathError:
                continue