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-${name}"
  29         fi
  30 }
  31
  32 lock() {
  33         local lock="${1}"
  34         shift
  35
  36         local timeout="60"
  37
  38         # Make partent directory
  39         make_parent_directory "${lock}"
  40
  41         (
  42                 log DEBUG "Trying to acquire lock ${lock}"
  43
  44                 # Try to acquire lock on fd 9
  45                 if ! flock -w "${timeout}" 9; then
  46                         log ERROR "Failed to acquire lock ${lock} after ${timeout} seconds"
  47                         exit ${EXIT_ERROR}
  48                 fi
  49
  50                 log DEBUG "Acquired lock ${lock}"
  51
  52                 # Remember return code
  53                 ret=${EXIT_OK}
  54
  55                 # Run command
  56                 "$@" || ret=$?
  57
  58                 log DEBUG "Released lock ${lock}"
  59
  60                 exit ${ret}
  61         ) 9>${lock} || exit $?
  62 }
  63
  64 lock_exists() {
  65         local name=${1}
  66         assert isset name
  67
  68         local lockfile=$(__lock_path ${name})
  69
  70         if [ -e "${lockfile}" ]; then
  71                 return ${EXIT_TRUE}
  72         else
  73                 return ${EXIT_FALSE}
  74         fi
  75 }
  76
  77 lock_acquire() {
  78         local name=${1}
  79         assert isset name
  80
  81         # timeout value in seconds
  82         local timeout=${2}
  83
  84         if ! isset timeout; then
  85                 timeout=0
  86         fi
  87
  88         local lockfile=$(__lock_path ${name})
  89
  90         timeout=$(( ${timeout} * 4 ))
  91
  92         log DEBUG "Acquiring lock '${name}'"
  93
  94         # Wait until lock is available
  95         while [ ${timeout} -gt 0 ] && [ -e "${lockfile}" ]; do
  96                 timeout=$(( ${timeout} - 1 ))
  97                 sleep 0.25
  98         done
  99
 100         # If another lock still exists, we return an error
 101         if [ -e "${lockfile}" ]; then
 102                 error "Could not acquire lock '${name}'"
 103                 return ${EXIT_ERROR}
 104         fi
 105
 106         # Write out pid to the lockfile and make sure that
 107         # nobody else can access it.
 108         echo "$$" > ${lockfile}
 109         chmod 600 ${lockfile}
 110 }
 111
 112 lock_release() {
 113         local name=${1}
 114         assert isset name
 115
 116         local lockfile=$(__lock_path ${name})
 117
 118         log DEBUG "Releasing lock '${name}'"
 119
 120         # Remove the lockfile (okay if it does not exist).
 121         rm -f ${lockfile}
 122 }