3 ### Make fake snapshots by remounting a filesystem readonly
5 ### (c) 2011 Mark Wooding
8 ###----- Licensing notice ---------------------------------------------------
10 ### This program is free software; you can redistribute it and/or modify
11 ### it under the terms of the GNU General Public License as published by
12 ### the Free Software Foundation; either version 2 of the License, or
13 ### (at your option) any later version.
15 ### This program is distributed in the hope that it will be useful,
16 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ### GNU General Public License for more details.
20 ### You should have received a copy of the GNU General Public License
21 ### along with this program; if not, write to the Free Software Foundation,
22 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
27 ###--------------------------------------------------------------------------
28 ### Parse the command line.
30 ## Provide help or version information.
31 usage="usage: $quis DEVICE [KEY=VALUE ...]"
32 version="$quis, version 1.0.0"
34 0,*) echo >&2 "$usage"; exit 1 ;;
35 *,-v | *,--version) echo "$version"; exit ;;
42 dir=MOUNTPT Mount point of filesystem.
43 op=OPERATION \`snap' to create snapshot, or \`unsnap' to remove.
44 tag=TAG Disambiguation tag to store in filesystem.
50 ## Scan the option keys.
57 *) echo >&2 "$quis: malformed option \`$i'"; exit 1 ;;
60 case "$k" in *.ro) k=${k%.ro} ;; ?*.?*) continue ;; esac
62 op | tag | dir) eval "O$k=\$v" ;;
63 *) echo >&2 "$quis: unknown option \`$k'"; win=nil ;;
66 case $win in nil) exit 1 ;; esac
68 ## Find a mount point if none was given.
69 sdn='s/^b[^ ]* *[^ ]* *[^ ]* *[^ ]* *\([0-9]*\), *\([0-9]*\) .*$/\1:\2/'
74 devno=$(ls -lL "/dev/$dev" | sed "$sdn")
77 *) echo >&2 "$quis: $dev is not a block device"; exit 1 ;;
79 while read <&3 d m fs hunoz; do
80 if [ ! -b "$d" ]; then continue; fi
81 dn=$(ls -lL "$d" | sed "$sdn")
85 t) echo >&2 "$quis: /dev/$dev mounted multiple times"; exit 1 ;;
95 t) ;; *) echo >&2 "$quis: /dev/$dev apparently not mounted"; exit 1 ;;
98 ###--------------------------------------------------------------------------
99 ### Take or remove the snapshot.
104 echo "$Otag" >"$Odir/.snap"
105 mount -oremount,ro "/dev/$dev" "$Odir"
110 if [ ! -f "$Odir/.snap" ]; then
111 echo >&2 "$quis: no snapshot tag"
114 read tag <"$Odir/.snap"
118 echo >&2 "$quis: tag mismatch (found \`$tag' but expected \`$Otag')"
122 mount -oremount,rw "/dev/$dev" "$Odir"
127 echo >&2 "$quis: unknown operation \`$Oop'"
133 ###----- That's all, folks --------------------------------------------------