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# udev.py
# Python module for querying the udev database for device information.
#
# Copyright (C) 2009 Red Hat, Inc.
#
# This copyrighted material is made available to anyone wishing to use,
# modify, copy, or redistribute it subject to the terms and conditions of
# the GNU General Public License v.2, or (at your option) any later version.
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY expressed or implied, including the implied warranties of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details. You should have received a copy of the
# GNU General Public License along with this program; if not, write to the
# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA. Any Red Hat trademarks that are incorporated in the
# source code or documentation are not subject to the GNU General Public
# License and may only be used or replicated with the express permission of
# Red Hat, Inc.
#
# Red Hat Author(s): Dave Lehman <dlehman@redhat.com>
# Chris Lumens <clumens@redhat.com>
#
import iutil
import os
import logging
log = logging.getLogger("storage")
def udev_enumerate_devices(deviceClass="block"):
top_dir = "/sys/class/%s" % deviceClass
devices = []
for dev_name in os.listdir(top_dir):
full_path = os.path.join(top_dir, dev_name)
link_ref = os.readlink(full_path)
real_path = os.path.join(top_dir, link_ref)
sysfs_path = os.path.normpath(real_path)
devices.append(sysfs_path)
return devices
def udev_get_device(sysfs_path):
if not os.path.exists(sysfs_path):
log.debug("%s does not exist" % sysfs_path)
return None
db_entry = sysfs_path[4:].replace("/", "\\x2f")
db_root = "/dev/.udev/db"
db_path = os.path.normpath("%s/%s" % (db_root, db_entry))
if not os.access(db_path, os.R_OK):
log.debug("db entry %s does not exist" % db_path)
return None
entry = open(db_path).read()
dev = udev_parse_entry(entry)
if dev.has_key("name"):
# XXX why do we do this? is /sys going to move during installation?
dev['sysfs_path'] = sysfs_path[4:] # strip off the leading '/sys'
dev = udev_parse_uevent_file(dev)
# now add in the contents of the uevent file since they're handy
return dev
def udev_get_devices(deviceClass="block"):
udev_settle(timeout=30)
entries = []
for path in udev_enumerate_devices(deviceClass):
entry = udev_get_device(path)
if entry:
entries.append(entry)
return entries
def udev_parse_entry(buf):
dev = {}
for line in buf.splitlines():
line.strip()
(tag, sep, val) = line.partition(":")
if not sep:
continue
if tag == "N":
dev['name'] = val
elif tag == "S":
if dev.has_key('symlinks'):
dev['symlinks'].append(val)
else:
dev['symlinks'] = [val]
elif tag == "E":
if val.count("=") > 1 and val.count(" ") > 0:
# eg: LVM2_LV_NAME when querying the VG for its LVs
vars = val.split()
vals = []
var_name = None
for (index, subval) in enumerate(vars):
(var_name, sep, var_val) = subval.partition("=")
if sep:
vals.append(var_val)
dev[var_name] = vals
else:
(var_name, sep, var_val) = val.partition("=")
if not sep:
continue
dev[var_name] = var_val
return dev
def udev_parse_uevent_file(dev):
path = os.path.normpath("/sys/%s/uevent" % dev['sysfs_path'])
if not os.access(path, os.R_OK):
return dev
with open(path) as f:
for line in f.readlines():
(key, equals, value) = line.strip().partition("=")
if not equals:
continue
dev[key] = value
return dev
def udev_settle(timeout=None):
argv = ["settle"]
if timeout:
argv.append("--timeout=%d" % int(timeout))
iutil.execWithRedirect("udevadm", argv, stderr="/dev/null", searchPath=1)
def udev_trigger(subsystem=None):
argv = ["trigger"]
if subsystem:
argv.append("--subsystem-match=%s" % subsystem)
iutil.execWithRedirect("udevadm", argv, stderr="/dev/null", searchPath=1)
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