Edit File: core.py
# -*- coding: utf-8 -*- # Copyright (C) 2010, 2011 Sebastian Wiesner <lunaryorn@googlemail.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@googlemail.com> """ from __future__ import (print_function, division, unicode_literals, absolute_import) try: from subprocess import check_output except ImportError: from pyudev._compat import check_output from pyudev.device import Device from pyudev._libudev import load_udev_library from pyudev._util import (ensure_unicode_string, ensure_byte_string, udev_list_iterate, property_value_to_bytes) __all__ = ['udev_version', 'Context', 'Enumerator'] def udev_version(): """ Get the version of the underlying udev library. udev doesn't use a standard major-minor versioning scheme, but instead labels releases with a single consecutive number. Consequently, the version number returned by this function is a single integer, and not a tuple (like for instance the interpreter version in :data:`sys.version_info`). As libudev itself does not provide a function to query the version number, this function calls the ``udevadm`` utilitiy, so be prepared to catch :exc:`~exceptions.EnvironmentError` and :exc:`~subprocess.CalledProcessError` if you call this function. Return the version number as single integer. Raise :exc:`~exceptions.ValueError`, if the version number retrieved from udev could not be converted to an integer. Raise :exc:`~exceptions.EnvironmentError`, if ``udevadm`` was not found, or could not be executed. Raise :exc:`subprocess.CalledProcessError`, if ``udevadm`` returned a non-zero exit code. On Python 2.7 or newer, the ``output`` attribute of this exception is correctly set. .. versionadded:: 0.8 """ output = ensure_unicode_string(check_output(['udevadm', '--version'])) return int(output.strip()) class Context(object): """ The udev context. This is *the* central object to access udev. An instance of this class must be created before anything else can be done. It holds the udev configuration and provides the interface to list devices (see :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_udev_library() 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. The mount point can be overwritten using the environment variable :envvar:`SYSFS_PATH`. Use this for testing purposes. """ return ensure_unicode_string(self._libudev.udev_get_sys_path(self)) @property def device_path(self): """ The device directory path defaulting to ``/dev`` as unicode string. This can be overridden in the udev configuration. """ return ensure_unicode_string(self._libudev.udev_get_dev_path(self)) @property def run_path(self): """ The run runtime directory path defaulting to ``/run`` as unicode string. .. udevversion:: 167 .. versionadded:: 0.10 """ return ensure_unicode_string(self._libudev.udev_get_run_path(self)) @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): 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): """ Enumerate all available 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 Added ``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 property, value in kwargs.iteritems(): self.match_property(property, 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``. Return the instance again. """ match = (self._libudev.udev_enumerate_add_match_subsystem if not nomatch else self._libudev.udev_enumerate_add_nomatch_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, property, value): """ Include all devices, whose ``property`` has the given ``value``. ``property`` 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(property), 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): yield Device.from_sys_path(self.context, name)