git.plutz.net Git - shellwiki/blob - session_lock.sh

   1 #!/bin/sh
   2
   3 [ "$include_sessionlock" ] && return 0
   4 include_sessionlock="$0"
   5
   6 . "$_EXEC/cgilite/storage.sh"
   7 . "$_EXEC/cgilite/session.sh"
   8
   9 LOCK_TIMEOUT="${LOCK_TIMEOUT:-1200}"
  10
  11 S_LOCK(){
  12   local file="$1" timeout="${2:-$LOCK_TIMEOUT}"
  13   local date sid
  14
  15   printf "%i %s\n" "$_DATE" "$SESSION_ID" >>"${file}.lock"
  16
  17   if ! read date sid <"${file}.lock"; then
  18     debug "Unable to access lock: ${file}.lock"
  19
  20   elif [ $((date + timeout)) -lt $_DATE ]; then
  21     # Override stale lock
  22     if LOCK "${file}.lock" 1; then
  23       debug "Overriding stale lock: ${file}.lock"
  24       printf "%i %s\n" "$_DATE" "$SESSION_ID" >"${file}.lock"
  25       RELEASE "${file}.lock"
  26       return 0
  27     else
  28       return 1
  29     fi
  30
  31   elif [ "$sid" = "$SESSION_ID" -a "$date" -ne "$_DATE" ]; then
  32     # Refresh aged lock
  33     printf "%i %s\n" "$_DATE" "$SESSION_ID" >"${file}.lock"
  34     return 0
  35
  36   elif [ "$sid" = "$SESSION_ID" ]; then
  37     # Simple success
  38     return 0
  39
  40   else
  41     return 1
  42   fi
  43 }
  44
  45 S_RELEASE(){
  46   local file="$1" timeout="${2:-$LOCK_TIMEOUT}"
  47   local date sid
  48
  49   if ! read date sid <"${file}.lock"; then
  50     # File was not locked
  51     return 0
  52
  53   elif [ "$sid" = "$SESSION_ID" -a  $((date + timeout)) -lt $_DATE ]; then
  54     # if lock is stale, protect against stale override before release
  55     if LOCK "${file}.lock" 1; then
  56       rm -- "${file}.lock"
  57       RELEASE "${file}.lock"
  58       return 0
  59     else
  60       return 1
  61     fi
  62
  63   elif [ "$sid" = "$SESSION_ID" ]; then
  64     # Simple success
  65     rm -- "${file}.lock"
  66     return 0
  67
  68   else
  69     return 1
  70   fi
  71 }