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# Copyright 2011 Google Inc.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program 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 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.
"""Timestamp handling routines."""
__author__ = "jaq@google.com (Jamie Wilkinson)"
import logging
import os.path
import tempfile
import time
import stat
import datetime
def ReadTimestamp(filename):
"""Return a timestamp from a file.
The timestamp file format is a single line, containing a string in the
ISO-8601 format YYYY-MM-DDThh:mm:ssZ (i.e. UTC time). We do not support
all ISO-8601 formats for reasons of convenience in the code.
Timestamps internal to nss_cache deliberately do not carry milliseconds.
Args:
filename: A String naming the file to read from.
Returns:
A time.struct_time, or None if the timestamp file doesn't
exist or has errors.
"""
if not os.path.exists(filename):
return None
try:
timestamp_file = open(filename, "r")
timestamp_string = timestamp_file.read().strip()
except IOError as e:
logging.warning("error opening timestamp file: %s", e)
timestamp_string = None
else:
timestamp_file.close()
logging.debug("read timestamp %s from file %r", timestamp_string, filename)
if timestamp_string is not None:
try:
# Append UTC to force the timezone to parse the string in.
timestamp = time.strptime(
timestamp_string + " UTC", "%Y-%m-%dT%H:%M:%SZ %Z"
)
except ValueError as e:
logging.error("cannot parse timestamp file %r: %s", filename, e)
timestamp = None
else:
timestamp = None
logging.debug("Timestamp is: %r", timestamp)
now = time.gmtime()
logging.debug(" Now is: %r", now)
if timestamp > now:
logging.warning(
"timestamp %r (%r) from %r is in the future, now is %r",
timestamp_string,
time.mktime(timestamp),
filename,
time.mktime(now),
)
if time.mktime(timestamp) - time.mktime(now) >= 60 * 60:
logging.info("Resetting timestamp to now.")
timestamp = now
return timestamp
def WriteTimestamp(timestamp, filename):
"""Write a given timestamp out to a file, converting to the ISO-8601
format.
We convert internal timestamp format (epoch) to ISO-8601 format, i.e.
YYYY-MM-DDThh:mm:ssZ which is basically UTC time, then write it out to a
file.
Args:
timestamp: A struct time.struct_time or time tuple.
filename: A String naming the file to write to.
Returns:
A boolean indicating success of write.
"""
# TODO(jaq): hack
if timestamp is None:
return True
timestamp_dir = os.path.dirname(filename)
(filedesc, temp_filename) = tempfile.mkstemp(
prefix="nsscache-update-", dir=timestamp_dir
)
time_string = time.strftime("%Y-%m-%dT%H:%M:%SZ", timestamp)
try:
os.write(filedesc, b"%s\n" % time_string.encode())
os.fsync(filedesc)
os.close(filedesc)
except OSError:
os.unlink(temp_filename)
logging.warning("writing timestamp failed!")
return False
os.chmod(temp_filename, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH)
os.rename(temp_filename, filename)
logging.debug("wrote timestamp %s to file %r", time_string, filename)
return True
def FromTimestampToDateTime(ts):
"""Converts internal nss_cache timestamp to datetime object.
Args:
ts: number of seconds since epoch
Returns:
datetime object
"""
return datetime.datetime.utcfromtimestamp(ts)
def FromDateTimeToTimestamp(datetime_obj):
"""Converts datetime object to internal nss_cache timestamp.
Args:
datetime object
Returns:
number of seconds since epoch
"""
dt = datetime_obj.replace(tzinfo=None)
return int((dt - datetime.datetime(1970, 1, 1)).total_seconds())
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