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

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# General Public License for more details.

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

"""

import os

from cStringIO import StringIO

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

  names = algo.UniqueSequence([hostname] + aliases)

  out = StringIO()

  def _write_entry(written):

    if not written:

      out.write("%s\t%s\n" % (ip, " ".join(names)))

    return True

  written = False

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

    fields = line.split()

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

      written = _write_entry(written)

    else:

      out.write(line)

  _write_entry(written)

  io.WriteFile(file_name, data=out.getvalue(), 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

  """

  out = StringIO()

  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)

  io.WriteFile(file_name, data=out.getvalue(), 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])