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#
# Copyright (C) 2012 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): Vratislav Podzimek <vpodzime@redhat.com>
#
"""
Module facilitating the work with NTP servers and NTP daemon's configuration
"""
import re
import os
import tempfile
import shutil
from pyanaconda import iutil
from pyanaconda.threads import threadMgr, AnacondaThread
NTP_CONFIG_FILE = "/etc/chrony.conf"
#example line:
#server 0.fedora.pool.ntp.org iburst
SRV_LINE_REGEXP = re.compile(r"^\s*server\s*([-a-zA-Z.0-9]+)\s*[a-zA-Z]+\s*$")
class NTPconfigError(Exception):
"""Exception class for NTP related problems"""
pass
def ntp_server_working(server):
"""
Runs rdate to try to connect to the $server (timeout may take some time).
@return: True if the given server is reachable and working, False otherwise
"""
#FIXME: It would be nice to use execWithRedirect here, but it is not
# thread-safe and hangs if this function is called from threads.
# By using tee (and block-buffered pipes) it is also much slower.
#we just need to know the exit status
retc = os.system("rdate -p %s &>/dev/null" % server)
return retc == 0
def get_servers_from_config(conf_file_path=NTP_CONFIG_FILE,
srv_regexp=SRV_LINE_REGEXP):
"""
Goes through the chronyd's configuration file looking for lines starting
with 'server'.
@return: servers found in the chronyd's configuration
@rtype: list
"""
ret = list()
try:
with open(conf_file_path, "r") as conf_file:
for line in conf_file:
match = srv_regexp.match(line)
if match:
ret.append(match.group(1))
except IOError as ioerr:
msg = "Cannot open config file %s for reading (%s)" % (conf_file_path,
ioerr.strerror)
raise NTPconfigError(msg)
return ret
def save_servers_to_config(servers, conf_file_path=NTP_CONFIG_FILE,
srv_regexp=SRV_LINE_REGEXP, out_file_path=None):
"""
Replaces the servers defined in the chronyd's configuration file with
the given ones. If the out_file is not None, then it is used for the
resulting config.
@type servers: iterable
@param out_file_path: path to the file used for the resulting config
"""
try:
old_conf_file = open(conf_file_path, "r")
except IOError as ioerr:
msg = "Cannot open config file %s for reading (%s)" % (conf_file_path,
ioerr.strerror)
raise NTPconfigError(msg)
try:
if out_file_path:
new_conf_file = open(out_file_path, "w")
else:
(fildes, temp_path) = tempfile.mkstemp()
new_conf_file = os.fdopen(fildes, "w")
except IOError as ioerr:
if out_file_path:
msg = "Cannot open new config file %s "\
"for writing (%s)" % (out_file_path, ioerr.strerror)
else:
msg = "Cannot open temporary file %s "\
"for writing (%s)" % (temp_path, ioerr.strerror)
raise NTPconfigError(msg)
heading = "# These servers were defined in the installation:\n"
#write info about the origin of the following lines
new_conf_file.write(heading)
#write new servers
for server in servers:
new_conf_file.write("server " + server + " iburst\n")
#copy non-server lines from the old config and skip our heading
for line in old_conf_file:
if not srv_regexp.match(line) and line != heading:
new_conf_file.write(line)
old_conf_file.close()
new_conf_file.close()
if not out_file_path:
try:
stat = os.stat(conf_file_path)
shutil.move(temp_path, conf_file_path)
os.chmod(conf_file_path, stat.st_mode)
except OSError as oserr:
msg = "Cannot replace the old config with "\
"the new one (%s)" % (oserr.strerror)
raise NTPconfigError(msg)
def one_time_sync(server, callback=None):
"""
Synchronize the system time with a given NTP server. Note that this
function is blocking and will not return until the time gets synced or
querying server fails (may take some time before timeouting).
@param server: NTP server
@param callback: callback function to run after sync or failure
@type callback: a function taking one boolean argument (success)
@return: True if the sync was successful, False otherwise
"""
ret = iutil.execWithRedirect("rdate", ["-s", server])
success = ret == 0
if callback is not None:
callback(success)
return success
def one_time_sync_async(server, callback=None):
"""
Asynchronously synchronize the system time with a given NTP server. This
function is non-blocking it starts a new thread for synchronization and
returns. Use callback argument to specify the function called when the
new thread finishes if needed.
@param server: NTP server
@param callback: callback function to run after sync or failure
@type callback: a function taking one boolean argument (success)
"""
thread_name = "AnaSyncTime_%s" % server
if threadMgr.get(thread_name):
#syncing with the same server running
return
threadMgr.add(AnacondaThread(name=thread_name, target=one_time_sync,
args=(server, callback)))
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