src/functions/functions.lock

   1 #!/bin/bash
   2 ###############################################################################
   3 #                                                                             #
   4 # IPFire.org - A linux based firewall                                         #
   5 # Copyright (C) 2012  Michael Tremer & Christian Schmidt                      #
   6 #                                                                             #
   7 # This program is free software: you can redistribute it and/or modify        #
   8 # it under the terms of the GNU General Public License as published by        #
   9 # the Free Software Foundation, either version 3 of the License, or           #
  10 # (at your option) any later version.                                         #
  11 #                                                                             #
  12 # This program is distributed in the hope that it will be useful,             #
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of              #
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
  15 # GNU General Public License for more details.                                #
  16 #                                                                             #
  17 # You should have received a copy of the GNU General Public License           #
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
  19 #                                                                             #
  20 ###############################################################################
  21
  22 __lock_path() {
  23         local name=${1}
  24
  25         if [ "${name:0:1}" = "/" ]; then
  26                 echo "${name}"
  27         else
  28                 echo "${LOCK_DIR}/network-${name}"
  29         fi
  30 }
  31
  32 lock_acquire() {
  33         local name=${1}
  34         assert isset name
  35
  36         local lockfile=$(__lock_path ${name})
  37
  38         # timeout value in seconds
  39         local timeout=120
  40         timeout=$(( ${timeout} * 4 ))
  41
  42         log DEBUG "Acquiring lock '${name}'"
  43
  44         local free="false"
  45         while [ ${timeout} -gt 0 ]; do
  46                 if [ ! -e "${lockfile}" ]; then
  47                         free="true"
  48                         break
  49                 fi
  50
  51                 timeout=$(( ${timeout} - 1 ))
  52                 sleep 0.25
  53         done
  54
  55         assert ${free} "Could not acquire lock '${name}'"
  56
  57         # Write out pid to the lockfile and make sure that
  58         # nobody else can access it.
  59         echo "$$" > ${lockfile}
  60         chmod 600 ${lockfile}
  61 }
  62
  63 lock_release() {
  64         local name=${1}
  65         assert isset name
  66
  67         local lockfile=$(__lock_path ${name})
  68
  69         log DEBUG "Releasing lock '${name}'"
  70
  71         # Remove the lockfile (okay if it does not exist).
  72         rm -f ${lockfile}
  73 }