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         # Move locks with name only into lock directory
  37         if [ "${lock:0:1}" != "/" ]; then
  38                 lock="${LOCK_DIR}/${lock}"
  39         fi
  40
  41         local timeout="60"
  42
  43         # Make partent directory
  44         make_parent_directory "${lock}"
  45
  46         (
  47                 log DEBUG "Trying to acquire lock ${lock}"
  48
  49                 # Try to acquire lock on fd 9
  50                 if ! flock -w "${timeout}" 9; then
  51                         log ERROR "Failed to acquire lock ${lock} after ${timeout} seconds"
  52                         exit ${EXIT_ERROR}
  53                 fi
  54
  55                 log DEBUG "Acquired lock ${lock}"
  56
  57                 # Remember return code
  58                 ret=${EXIT_OK}
  59
  60                 # Run command
  61                 "$@" || ret=$?
  62
  63                 log DEBUG "Released lock ${lock}"
  64
  65                 exit ${ret}
  66         ) 9>${lock} || exit $?
  67 }
  68
  69 lock_exists() {
  70         local name=${1}
  71         assert isset name
  72
  73         local lockfile=$(__lock_path ${name})
  74
  75         if [ -e "${lockfile}" ]; then
  76                 return ${EXIT_TRUE}
  77         else
  78                 return ${EXIT_FALSE}
  79         fi
  80 }
  81
  82 lock_acquire() {
  83         local name=${1}
  84         assert isset name
  85
  86         # timeout value in seconds
  87         local timeout=${2}
  88
  89         if ! isset timeout; then
  90                 timeout=0
  91         fi
  92
  93         local lockfile=$(__lock_path ${name})
  94
  95         timeout=$(( ${timeout} * 4 ))
  96
  97         log DEBUG "Acquiring lock '${name}'"
  98
  99         # Wait until lock is available
 100         while [ ${timeout} -gt 0 ] && [ -e "${lockfile}" ]; do
 101                 timeout=$(( ${timeout} - 1 ))
 102                 sleep 0.25
 103         done
 104
 105         # If another lock still exists, we return an error
 106         if [ -e "${lockfile}" ]; then
 107                 error "Could not acquire lock '${name}'"
 108                 return ${EXIT_ERROR}
 109         fi
 110
 111         # Write out pid to the lockfile and make sure that
 112         # nobody else can access it.
 113         echo "$$" > ${lockfile}
 114         chmod 600 ${lockfile}
 115 }
 116
 117 lock_release() {
 118         local name=${1}
 119         assert isset name
 120
 121         local lockfile=$(__lock_path ${name})
 122
 123         log DEBUG "Releasing lock '${name}'"
 124
 125         # Remove the lockfile (okay if it does not exist).
 126         rm -f ${lockfile}
 127 }