user-tools/chattr-nocow

   1 #!/bin/bash
   2
   3 true <<EOF
   4 =pod
   5
   6 =head1 NAME
   7
   8 chattr-cow - try hard to enable Copy-on-Write attribute on files
   9
  10 chattr-nocow - try hard to disable Copy-on-Write attribute on files
  11
  12 =cut
  13
  14 EOF
  15
  16
  17 set -e
  18 set -u
  19
  20 . /usr/lib/tool/bash-utils
  21
  22
  23 is_cow()
  24 {
  25         lsattr -d "$1" | cut -f1 -d' ' | grep -qv 'C'
  26 }
  27
  28 set_cow()
  29 {
  30         local onoff file tmpf expected_cow current_dir_cow
  31         local sigs="ERR RETURN INT QUIT TERM"
  32
  33         onoff=$1
  34         file=$2
  35         tmpf=$file.set-no-cow
  36         dir=`dirname "$file"`
  37
  38         [ $onoff = on ] && expected_cow=-C || expected_cow=+C
  39         is_cow "$dir" && current_dir_cow=-C || current_dir_cow=+C
  40
  41         if [ $expected_cow != $current_dir_cow ]
  42         then
  43                 chattr $expected_cow "$dir"
  44                 trap 'trap - $sigs; chattr $current_dir_cow "$dir"' $sigs
  45         fi
  46
  47         cp -f --preserve=mode,ownership,timestamps,xattr --no-preserve=links "$file" "$tmpf"
  48         mv -f "$tmpf" "$file"
  49         return
  50 }
  51
  52 is_in_use()
  53 {
  54         lsof -Fp -- "$1" >/dev/null 2>&1
  55 }
  56
  57
  58 case "${0##*/}" in
  59 chattr-nocow)
  60         cow=off
  61         expected_cow=+C
  62         ;;
  63 chattr-cow)
  64         cow=on
  65         expected_cow=-C
  66         ;;
  67 *)
  68         errx 38 "bad invocation"
  69         ;;
  70 esac
  71
  72 for file in "$@"
  73 do
  74         if [ -d "$file" ]
  75         then
  76                 chattr $expected_cow "$file"
  77         else
  78                 if is_in_use "$file"
  79                 then
  80                         errx 16 "$file: is in use"
  81                 else
  82                         set_cow $cow "$file"
  83                 fi
  84         fi
  85 done
  86
  87 exit 0