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- #
- # Copyright 2013, Martin Owens <doctormo@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 3.0 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.
- #
- """
- Access logs in known locations to find information about them.
- """
- import os
- import re
- import codecs
- import platform
- PY3 = platform.python_version()[0] == '3'
- if PY3:
- # pylint: disable=W0622
- unicode = str
- basestring = str
- from dateutil import parser as dateparse
- MATCHER = r'(?P<date>\w+ +\d+ +\d\d:\d\d:\d\d) (?P<host>\w+) ' + \
- r'CRON\[(?P<pid>\d+)\]: \((?P<user>\w+)\) CMD \((?P<cmd>.*)\)'
- class LogReader(object):
- """Opens a Log file, reading backwards and watching for changes"""
- def __init__(self, filename, mass=4096):
- self.filename = filename
- self.mass = mass
- self.size = -1
- self.read = -1
- self.pipe = None
- def __enter__(self):
- self.size = os.stat(self.filename)[6]
- self.pipe = codecs.open(self.filename, 'r', encoding='utf-8')
- return self
- def __exit__(self, error_type, value, traceback):
- self.pipe.close()
- def __iter__(self):
- if self.pipe is None:
- with self as reader:
- for (offset, line) in reader.readlines():
- yield line
- else:
- for (offset, line) in self.readlines():
- yield line
- def readlines(self, until=0):
- """Iterator for reading lines from a file backwards"""
- if not self.pipe or self.pipe.closed:
- raise IOError("Can't readline, no opened file.")
- # Always seek to the end of the file, this accounts for file updates
- # that happen during our running process.
- location = self.size
- halfline = ''
- while location > until:
- location -= self.mass
- mass = self.mass
- if location < 0:
- mass = self.mass + location
- location = 0
- self.pipe.seek(location)
- line = self.pipe.read(mass) + halfline
- data = line.split('\n')
- if location != 0:
- halfline = data.pop(0)
- loc = location + mass
- data.reverse()
- for line in data:
- if line.strip() == '':
- continue
- yield (loc, line)
- loc -= len(line)
- class CronLog(LogReader):
- """Use the LogReader to make a Cron specific log reader"""
- def __init__(self, filename='/var/log/syslog', user=None):
- LogReader.__init__(self, filename)
- self.user = user
- def for_program(self, command):
- """Return log entries for this specific command name"""
- return ProgramLog(self, command)
- def __iter__(self):
- for line in super(CronLog, self).__iter__():
- match = re.match(MATCHER, unicode(line))
- datum = match and match.groupdict()
- if datum and (not self.user or datum['user'] == self.user):
- datum['date'] = dateparse.parse(datum['date'])
- yield datum
- class ProgramLog(object):
- """Specific log control for a single command/program"""
- def __init__(self, log, command):
- self.log = log
- self.command = command
- def __iter__(self):
- for entry in self.log:
- if entry['cmd'] == unicode(self.command):
- yield entry
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