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

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