[distorted-backup] / snap.ro

#! /bin/sh
###
### Make fake snapshots by remounting a filesystem readonly
###
### (c) 2011 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This file is part of the distorted.org.uk backup suite.
###
### distorted-backup is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### distorted-backup is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License along
### with distorted-backup; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

set -e
quis=${0##*/}

###--------------------------------------------------------------------------
### Parse the command line.

## Provide help or version information.
usage="usage: $quis DEVICE [KEY=VALUE ...]"
version="$quis, version 1.0.0"
case "$#,$1" in
  0,*) echo >&2 "$usage"; exit 1 ;;
  *,-v | *,--version) echo "$version"; exit ;;
  *,-h | *,--help)
    cat <<EOF
$version
$usage

Option keys:
  dir=MOUNTPT		Mount point of filesystem.
  op=OPERATION		\`snap' to create snapshot, or \`unsnap' to remove.
  tag=TAG		Disambiguation tag to store in filesystem.
EOF
    exit
    ;;
esac

## Scan the option keys.
dev=$1; shift
Oop=snap Otag=snap
win=t
for i in "$@"; do
  case "$i" in
    ?*=*) ;;
    *) echo >&2 "$quis: malformed option \`$i'"; exit 1 ;;
  esac
  k=${i%%=*} v=${i#*=}
  case "$k" in *.ro) k=${k%.ro} ;; ?*.?*) continue ;; esac
  case "$k" in
    op | tag | dir) eval "O$k=\$v" ;;
    *) echo >&2 "$quis: unknown option \`$k'"; win=nil ;;
  esac
done
case $win in nil) exit 1 ;; esac

## Find a mount point if none was given.
sdn='s/^b[^ ]*  *[^ ]*  *[^ ]*  *[^ ]*  *\([0-9]*\),  *\([0-9]*\) .*$/\1:\2/'
case "${Odir+t}" in
  t) ;;
  *)
    exec 3</etc/mtab
    devno=$(ls -lL "/dev/$dev" | sed "$sdn")
    case "$devno" in
      *:*) ;;
      *) echo >&2 "$quis: $dev is not a block device"; exit 1 ;;
    esac
    while read <&3 d m fs hunoz; do
      if [ ! -b "$d" ]; then continue; fi
      dn=$(ls -lL "$d" | sed "$sdn")
      case "$dn" in
	"$devno")
	  case "${Odir+t}" in
	    t) echo >&2 "$quis: /dev/$dev mounted multiple times"; exit 1 ;;
	  esac
	  Odir=$m
	  ;;
      esac
    done
    exec 3>&-
    ;;
esac
case "${Odir+t}" in
  t) ;; *) echo >&2 "$quis: /dev/$dev apparently not mounted"; exit 1 ;;
esac

###--------------------------------------------------------------------------
### Take or remove the snapshot.

case "$Oop" in

  snap)
    echo "$Otag" >"$Odir/.snap"
    mount -oremount,ro "/dev/$dev" "$Odir"
    echo "$dev"
    ;;

  unsnap)
    if [ ! -f "$Odir/.snap" ]; then
      echo >&2 "$quis: no snapshot tag"
      exit 1
    fi
    read tag <"$Odir/.snap"
    case "$tag" in
      "$Otag") ;;
      *)
	echo >&2 "$quis: tag mismatch (found \`$tag' but expected \`$Otag')"
	exit 1
	;;
    esac
    mount -oremount,rw "/dev/$dev" "$Odir"
    rm "$Odir/.snap"
    ;;

  *)
    echo >&2 "$quis: unknown operation \`$Oop'"
    exit 1
    ;;

esac

###----- That's all, folks --------------------------------------------------
Commit	Line	Data
99248ed2 MW	1	#! /bin/sh
	2	###
	3	### Make fake snapshots by remounting a filesystem readonly
	4	###
	5	### (c) 2011 Mark Wooding
	6	###
	7
	8	###----- Licensing notice ---------------------------------------------------
	9	###
13678d88 MW	10	### This file is part of the distorted.org.uk backup suite.
	11	###
	12	### distorted-backup is free software; you can redistribute it and/or modify
99248ed2 MW	13	### it under the terms of the GNU General Public License as published by
	14	### the Free Software Foundation; either version 2 of the License, or
	15	### (at your option) any later version.
	16	###
13678d88	17	### distorted-backup is distributed in the hope that it will be useful,
99248ed2 MW	18	### but WITHOUT ANY WARRANTY; without even the implied warranty of
	19	### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	20	### GNU General Public License for more details.
	21	###
13678d88 MW	22	### You should have received a copy of the GNU General Public License along
13678d88 MW	23	### with distorted-backup; if not, write to the Free Software Foundation,
99248ed2 MW	24	### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	25
	26	set -e
	27	quis=${0##*/}
	28
	29	###--------------------------------------------------------------------------
	30	### Parse the command line.
	31
	32	## Provide help or version information.
	33	usage="usage: $quis DEVICE [KEY=VALUE ...]"
	34	version="$quis, version 1.0.0"
	35	case "$#,$1" in
	36	0,*) echo >&2 "$usage"; exit 1 ;;
	37	,-v \| ,--version) echo "$version"; exit ;;
	38	,-h \| ,--help)
	39	cat <<EOF
	40	$version
	41	$usage
	42
	43	Option keys:
	44	dir=MOUNTPT Mount point of filesystem.
	45	op=OPERATION \`snap' to create snapshot, or \`unsnap' to remove.
	46	tag=TAG Disambiguation tag to store in filesystem.
	47	EOF
	48	exit
	49	;;
	50	esac
	51
	52	## Scan the option keys.
	53	dev=$1; shift
	54	Oop=snap Otag=snap
	55	win=t
	56	for i in "$@"; do
	57	case "$i" in
	58	?=) ;;
	59	*) echo >&2 "$quis: malformed option \`$i'"; exit 1 ;;
	60	esac
	61	k=${i%%=} v=${i#=}
	62	case "$k" in .ro) k=${k%.ro} ;; ?.?*) continue ;; esac
	63	case "$k" in
	64	op \| tag \| dir) eval "O$k=\$v" ;;
	65	*) echo >&2 "$quis: unknown option \`$k'"; win=nil ;;
	66	esac
	67	done
	68	case $win in nil) exit 1 ;; esac
	69
	70	## Find a mount point if none was given.
	71	sdn='s/^b[^ ]* [^ ] [^ ] [^ ] \([0-9]\), \([0-9]\) .*$/\1:\2/'
	72	case "${Odir+t}" in
	73	t) ;;
	74	*)
	75	exec 3</etc/mtab
	76	devno=$(ls -lL "/dev/$dev" \| sed "$sdn")
	77	case "$devno" in
	78	:) ;;
	79	*) echo >&2 "$quis: $dev is not a block device"; exit 1 ;;
	80	esac
	81	while read <&3 d m fs hunoz; do
	82	if [ ! -b "$d" ]; then continue; fi
	83	dn=$(ls -lL "$d" \| sed "$sdn")
	84	case "$dn" in
	85	"$devno")
	86	case "${Odir+t}" in
	87	t) echo >&2 "$quis: /dev/$dev mounted multiple times"; exit 1 ;;
88	esac
89	Odir=$m
90	;;
91	esac
92	done
93	exec 3>&-
94	;;
95	esac
96	case "${Odir+t}" in
97	t) ;; *) echo >&2 "$quis: /dev/$dev apparently not mounted"; exit 1 ;;
98	esac
99
100	###--------------------------------------------------------------------------
101	### Take or remove the snapshot.
102
103	case "$Oop" in
104
105	snap)
106	echo "$Otag" >"$Odir/.snap"
107	mount -oremount,ro "/dev/$dev" "$Odir"
108	echo "$dev"
109	;;
110
111	unsnap)
112	if [ ! -f "$Odir/.snap" ]; then
113	echo >&2 "$quis: no snapshot tag"
114	exit 1
115	fi
116	read tag <"$Odir/.snap"
117	case "$tag" in
118	"$Otag") ;;
119	*)
120	echo >&2 "$quis: tag mismatch (found \`$tag' but expected \`$Otag')"
121	exit 1
122	;;
123	esac
124	mount -oremount,rw "/dev/$dev" "$Odir"
125	rm "$Odir/.snap"
126	;;
127
128	*)
129	echo >&2 "$quis: unknown operation \`$Oop'"
130	exit 1
131	;;
132
133	esac
134
135	###----- That's all, folks --------------------------------------------------