mirror of https://github.com/fail2ban/fail2ban
132 lines
4.4 KiB
Python
132 lines
4.4 KiB
Python
# This file is part of Fail2Ban.
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#
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# Fail2Ban is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# Fail2Ban is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Fail2Ban; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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# Author: Cyril Jaquier
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#
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# $Revision: 1.1.2.4 $
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__author__ = "Cyril Jaquier"
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__version__ = "$Revision: 1.1.2.4 $"
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__date__ = "$Date: 2005/08/04 20:48:30 $"
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__copyright__ = "Copyright (c) 2004 Cyril Jaquier"
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__license__ = "GPL"
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import os, logging, signal
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# Gets the instance of the logger.
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logSys = logging.getLogger("fail2ban")
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def createDaemon():
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""" Detach a process from the controlling terminal and run it in the
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background as a daemon.
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http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278731
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"""
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try:
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# Fork a child process so the parent can exit. This will return control
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# to the command line or shell. This is required so that the new process
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# is guaranteed not to be a process group leader. We have this guarantee
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# because the process GID of the parent is inherited by the child, but
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# the child gets a new PID, making it impossible for its PID to equal its
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# PGID.
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pid = os.fork()
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except OSError, e:
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return((e.errno, e.strerror)) # ERROR (return a tuple)
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if (pid == 0): # The first child.
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# Next we call os.setsid() to become the session leader of this new
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# session. The process also becomes the process group leader of the
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# new process group. Since a controlling terminal is associated with a
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# session, and this new session has not yet acquired a controlling
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# terminal our process now has no controlling terminal. This shouldn't
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# fail, since we're guaranteed that the child is not a process group
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# leader.
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os.setsid()
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# When the first child terminates, all processes in the second child
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# are sent a SIGHUP, so it's ignored.
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signal.signal(signal.SIGHUP, signal.SIG_IGN)
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try:
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# Fork a second child to prevent zombies. Since the first child is
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# a session leader without a controlling terminal, it's possible for
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# it to acquire one by opening a terminal in the future. This second
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# fork guarantees that the child is no longer a session leader, thus
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# preventing the daemon from ever acquiring a controlling terminal.
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pid = os.fork() # Fork a second child.
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except OSError, e:
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return((e.errno, e.strerror)) # ERROR (return a tuple)
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if (pid == 0): # The second child.
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# Ensure that the daemon doesn't keep any directory in use. Failure
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# to do this could make a filesystem unmountable.
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os.chdir("/")
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else:
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os._exit(0) # Exit parent (the first child) of the second child.
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else:
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os._exit(0) # Exit parent of the first child.
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# Close all open files. Try the system configuration variable, SC_OPEN_MAX,
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# for the maximum number of open files to close. If it doesn't exist, use
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# the default value (configurable).
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try:
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maxfd = os.sysconf("SC_OPEN_MAX")
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except (AttributeError, ValueError):
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maxfd = 256 # default maximum
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for fd in range(0, maxfd):
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try:
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os.close(fd)
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except OSError: # ERROR (ignore)
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pass
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# Redirect the standard file descriptors to /dev/null.
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os.open("/dev/null", os.O_RDONLY) # standard input (0)
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os.open("/dev/null", os.O_RDWR) # standard output (1)
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os.open("/dev/null", os.O_RDWR) # standard error (2)
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return True
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def killPID(pid):
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""" Kills the process with the given PID using the
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INT signal (same effect as <ctrl>+<c>).
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"""
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try:
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return os.kill(pid, 2)
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except OSError:
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logSys.error("Can not kill process " + `pid` + ". Please check that " +
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"Fail2Ban is not running and remove the file " +
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"'/tmp/fail2ban.pid'")
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return False
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def executeCmd(cmd, debug):
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""" Executes an OS command.
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"""
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if cmd == "":
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logSys.debug("Nothing to do")
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return None
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logSys.debug(cmd)
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if not debug:
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retval = os.system(cmd)
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if not retval == 0:
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logSys.error("'" + cmd + "' returned " + `retval`)
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return retval
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else:
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return None
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