[distorted-backup] / snap.ro

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

###----- Licensing notice ---------------------------------------------------
###
### This program 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.
###
### This program 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 this program; 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	###
	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.
	14	###
	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.
	19	###
	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.
	23
	24	set -e
	25	quis=${0##*/}
	26
	27	###--------------------------------------------------------------------------
	28	### Parse the command line.
	29
	30	## Provide help or version information.
	31	usage="usage: $quis DEVICE [KEY=VALUE ...]"
	32	version="$quis, version 1.0.0"
	33	case "$#,$1" in
	34	0,*) echo >&2 "$usage"; exit 1 ;;
	35	,-v \| ,--version) echo "$version"; exit ;;
	36	,-h \| ,--help)
	37	cat <<EOF
	38	$version
	39	$usage
	40
	41	Option keys:
	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.
	45	EOF
	46	exit
	47	;;
	48	esac
	49
	50	## Scan the option keys.
	51	dev=$1; shift
	52	Oop=snap Otag=snap
	53	win=t
	54	for i in "$@"; do
	55	case "$i" in
	56	?=) ;;
	57	*) echo >&2 "$quis: malformed option \`$i'"; exit 1 ;;
	58	esac
	59	k=${i%%=} v=${i#=}
	60	case "$k" in .ro) k=${k%.ro} ;; ?.?*) continue ;; esac
	61	case "$k" in
	62	op \| tag \| dir) eval "O$k=\$v" ;;
	63	*) echo >&2 "$quis: unknown option \`$k'"; win=nil ;;
	64	esac
65	done
66	case $win in nil) exit 1 ;; esac
67
68	## Find a mount point if none was given.
69	sdn='s/^b[^ ]* [^ ] [^ ] [^ ] \([0-9]\), \([0-9]\) .*$/\1:\2/'
70	case "${Odir+t}" in
71	t) ;;
72	*)
73	exec 3</etc/mtab
74	devno=$(ls -lL "/dev/$dev" \| sed "$sdn")
75	case "$devno" in
76	:) ;;
77	*) echo >&2 "$quis: $dev is not a block device"; exit 1 ;;
78	esac
79	while read <&3 d m fs hunoz; do
80	if [ ! -b "$d" ]; then continue; fi
81	dn=$(ls -lL "$d" \| sed "$sdn")
82	case "$dn" in
83	"$devno")
84	case "${Odir+t}" in
85	t) echo >&2 "$quis: /dev/$dev mounted multiple times"; exit 1 ;;
86	esac
87	Odir=$m
88	;;
89	esac
90	done
91	exec 3>&-
92	;;
93	esac
94	case "${Odir+t}" in
95	t) ;; *) echo >&2 "$quis: /dev/$dev apparently not mounted"; exit 1 ;;
96	esac
97
98	###--------------------------------------------------------------------------
99	### Take or remove the snapshot.
100
101	case "$Oop" in
102
103	snap)
104	echo "$Otag" >"$Odir/.snap"
105	mount -oremount,ro "/dev/$dev" "$Odir"
106	echo "$dev"
107	;;
108
109	unsnap)
110	if [ ! -f "$Odir/.snap" ]; then
111	echo >&2 "$quis: no snapshot tag"
112	exit 1
113	fi
114	read tag <"$Odir/.snap"
115	case "$tag" in
116	"$Otag") ;;
117	*)
118	echo >&2 "$quis: tag mismatch (found \`$tag' but expected \`$Otag')"
119	exit 1
120	;;
121	esac
122	mount -oremount,rw "/dev/$dev" "$Odir"
123	rm "$Odir/.snap"
124	;;
125
126	*)
127	echo >&2 "$quis: unknown operation \`$Oop'"
128	exit 1
129	;;
130
131	esac
132
133	###----- That's all, folks --------------------------------------------------