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# Copyright (C) 2006, 2007, 2010, 2011 Google Inc.

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# This program is free software; you can redistribute it and/or modify

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# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

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# 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.

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# 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.

"""Utility functions for manipulating /etc/hosts.

"""

import os

from ganeti import constants

from ganeti.utils import algo

from ganeti.utils import io

def SetEtcHostsEntry(file_name, ip, hostname, aliases):

  """Sets the name of an IP address and hostname in /etc/hosts.

  @type file_name: str

  @param file_name: path to the file to modify (usually C{/etc/hosts})

  @type ip: str

  @param ip: the IP address

  @type hostname: str

  @param hostname: the hostname to be added

  @type aliases: list

  @param aliases: the list of aliases to add for the hostname

  """

  # Ensure aliases are unique

  aliases = algo.UniqueSequence([hostname] + aliases)[1:]

  def _WriteEtcHosts(fd):

    # Duplicating file descriptor because os.fdopen's result will automatically

    # close the descriptor, but we would still like to have its functionality.

    out = os.fdopen(os.dup(fd), "w")

    try:

      for line in io.ReadFile(file_name).splitlines(True):

        fields = line.split()

        if fields and not fields[0].startswith("#") and ip == fields[0]:

          continue

        out.write(line)

      out.write("%s\t%s" % (ip, hostname))

      if aliases:

        out.write(" %s" % " ".join(aliases))

      out.write("\n")

      out.flush()

    finally:

      out.close()

  io.WriteFile(file_name, fn=_WriteEtcHosts, mode=0644)

def AddHostToEtcHosts(hostname, ip):

  """Wrapper around SetEtcHostsEntry.

  @type hostname: str

  @param hostname: a hostname that will be resolved and added to

      L{constants.ETC_HOSTS}

  @type ip: str

  @param ip: The ip address of the host

  """

  SetEtcHostsEntry(constants.ETC_HOSTS, ip, hostname, [hostname.split(".")[0]])

def RemoveEtcHostsEntry(file_name, hostname):

  """Removes a hostname from /etc/hosts.

  IP addresses without names are removed from the file.

  @type file_name: str

  @param file_name: path to the file to modify (usually C{/etc/hosts})

  @type hostname: str

  @param hostname: the hostname to be removed

  """

  def _WriteEtcHosts(fd):

    # Duplicating file descriptor because os.fdopen's result will automatically

    # close the descriptor, but we would still like to have its functionality.

    out = os.fdopen(os.dup(fd), "w")

    try:

      for line in io.ReadFile(file_name).splitlines(True):

        fields = line.split()

        if len(fields) > 1 and not fields[0].startswith("#"):

          names = fields[1:]

          if hostname in names:

            while hostname in names:

              names.remove(hostname)

            if names:

              out.write("%s %s\n" % (fields[0], " ".join(names)))

            continue

        out.write(line)

      out.flush()

    finally:

      out.close()

  io.WriteFile(file_name, fn=_WriteEtcHosts, mode=0644)

def RemoveHostFromEtcHosts(hostname):

  """Wrapper around RemoveEtcHostsEntry.

  @type hostname: str

  @param hostname: hostname that will be resolved and its

      full and shot name will be removed from

      L{constants.ETC_HOSTS}

  """

  RemoveEtcHostsEntry(constants.ETC_HOSTS, hostname)

  RemoveEtcHostsEntry(constants.ETC_HOSTS, hostname.split(".")[0])