#!/usr/bin/env bash
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# $Id: managesnapshot.sh 11601 2010-08-11 17:26:15Z kris $ $HeadURL: svn://svn.lab.vmops.com/repos/branches/2.1.refactor/java/scripts/storage/qcow2/managesnapshot.sh $
# managesnapshot.sh -- manage snapshots for a single disk (create, destroy, rollback, backup)

usage() {
  printf "Usage: %s: -c <path to disk> -n <snapshot name>\n" $(basename $0) >&2
  printf "Usage: %s: -d <path to disk> -n <snapshot name>\n" $(basename $0) >&2
  printf "Usage: %s: -r <path to disk> -n <snapshot name>\n" $(basename $0) >&2
  printf "Usage: %s: -b <path to disk> -n <snapshot name> -p <dest dir> -t <dest file>\n" $(basename $0) >&2
  exit 2
}

qemu_img="cloud-qemu-img"
which $qemu_img >& /dev/null
if [ $? -gt 0 ]
then
   which qemu-img >& /dev/null
   if [ $? -eq 0 ]
   then
       qemu_img="qemu-img"
   fi
fi

is_lv() {
	# Must be a block device
	if [ -b "${1}"  -o  -L "{1}" ]; then
		# But not a volume group or physical volume
		lvm vgs "${1}" > /dev/null 2>&1 && return 1
		# And a logical volume
		lvm lvs "${1}" > /dev/null 2>&1 && return 1
	fi
	return 0
}

get_vg() {
	lvm lvs --noheadings --unbuffered --separator=/ "${1}" | cut -d '/' -f 2
}

get_lv() {
	lvm lvs --noheadings --unbuffered --separator=/ "${1}" | cut -d '/' -f 1
}

double_hyphens() {
	echo ${1} | sed -e "s/-/--/g"
}

create_snapshot() {
  local disk=$1
  local snapshotname="$2"
  local failed=0
  is_lv ${disk}
  islv_ret=$?

  if [ ${dmsnapshot} = "yes" ] && [ "$islv_ret" == "1" ]; then
    local lv=`get_lv ${disk}`
    local vg=`get_vg ${disk}`
    local lv_dm=`double_hyphens ${lv}`
    local vg_dm=`double_hyphens ${vg}`
    local lvdevice=/dev/mapper/${vg_dm}-${lv_dm}
    local lv_bytes=`blockdev --getsize64 ${lvdevice}`
    local lv_sectors=`blockdev --getsz ${lvdevice}`

    lvm lvcreate --size ${lv_bytes}b --name "${snapshotname}-cow" ${vg} >&2 || return 2
    dmsetup suspend ${vg_dm}-${lv_dm} >&2
    if dmsetup info -c --noheadings -o name ${vg_dm}-${lv_dm}-real > /dev/null 2>&1; then
      echo "0 ${lv_sectors} snapshot ${lvdevice}-real /dev/mapper/${vg_dm}-${snapshotname}--cow p 64" | \
       dmsetup create "${vg_dm}-${snapshotname}" >&2 || ( destroy_snapshot ${disk} "${snapshotname}"; return 2 )
      dmsetup resume "${vg_dm}-${snapshotname}" >&2 || ( destroy_snapshot ${disk} "${snapshotname}"; return 2 )
    else
      dmsetup table ${vg_dm}-${lv_dm} | dmsetup create ${vg_dm}-${lv_dm}-real >&2 || ( destroy_snapshot ${disk} "${snapshotname}"; return 2 )
      dmsetup resume ${vg_dm}-${lv_dm}-real >&2 || ( destroy_snapshot ${disk} "${snapshotname}"; return 2 )
      echo "0 ${lv_sectors} snapshot ${lvdevice}-real /dev/mapper/${vg_dm}-${snapshotname}--cow p 64" | \
       dmsetup create "${vg_dm}-${snapshotname}" >&2 || ( destroy_snapshot ${disk} "${snapshotname}"; return 2 )
      echo "0 ${lv_sectors} snapshot-origin ${lvdevice}-real" | \
       dmsetup load ${vg_dm}-${lv_dm} >&2 || ( destroy_snapshot ${disk} "${snapshotname}"; return 2 )
      dmsetup resume "${vg_dm}-${snapshotname}" >&2 || ( destroy_snapshot ${disk} "${snapshotname}"; return 2 )
    fi
    dmsetup resume "${vg_dm}-${lv_dm}" >&2
  elif [ -f "${disk}" ]; then
     $qemu_img snapshot -c "$snapshotname" $disk


     if [ $? -gt 0 ]
     then
       failed=2
       printf "***Failed to create snapshot $snapshotname for path $disk\n" >&2
       $qemu_img snapshot -d "$snapshotname" $disk

       if [ $? -gt 0 ]
       then
          printf "***Failed to delete snapshot $snapshotname for path $disk\n" >&2
       fi
     fi
 else
    failed=3
    printf "***Failed to create snapshot $snapshotname, undefined type $disk\n" >&2
 fi

  return $failed
}

destroy_snapshot() {
  local disk=$1
  local snapshotname="$2"
  local failed=0
  is_lv ${disk}
  islv_ret=$?

  if [ "$islv_ret" == "1" ]; then
    local lv=`get_lv ${disk}`
    local vg=`get_vg ${disk}`
    local lv_dm=`double_hyphens ${lv}`
    local vg_dm=`double_hyphens ${vg}`
    if [ -e /dev/mapper/${vg_dm}-${lv_dm}-real ]; then
      local dm_refcount=`dmsetup info -c --noheadings -o open ${vg_dm}-${lv_dm}-real`
      if [ ${dm_refcount} -le 2 ]; then
        dmsetup suspend ${vg_dm}-${lv_dm} >&2
        dmsetup table ${vg_dm}-${lv_dm}-real | dmsetup load ${vg_dm}-${lv_dm} >&2
        dmsetup resume ${vg_dm}-${lv_dm}
        dmsetup remove "${vg_dm}-${snapshotname}"
        dmsetup remove ${vg_dm}-${lv_dm}-real
      else
        dmsetup remove "${vg_dm}-${snapshotname}"
      fi
    else
      dmsetup remove "${vg_dm}-${snapshotname}"
    fi
    lvm lvremove -f "${vg}/${snapshotname}-cow"
  elif [ -f $disk ]; then
     $qemu_img snapshot -d "$snapshotname" $disk
     if [ $? -gt 0 ]
     then
       failed=2
       printf "Failed to delete snapshot $snapshotname for path $disk\n" >&2
     fi
  else
     failed=3
     printf "***Failed to delete snapshot $snapshotname, undefined type $disk\n" >&2
  fi
  return $failed
}

rollback_snapshot() {
  local disk=$1
  local snapshotname="$2"
  local failed=0

  $qemu_img snapshot -a $snapshotname $disk

  if [ $? -gt 0 ]
  then
    printf "***Failed to apply snapshot $snapshotname for path $disk\n" >&2
    failed=1
  fi

  return $failed
}

backup_snapshot() {
  local disk=$1
  local snapshotname="$2"
  local destPath=$3
  local destName=$4

  if [ ! -d $destPath ]
  then
     mkdir -p $destPath >& /dev/null
     if [ $? -gt 0 ]
     then
        printf "Failed to create $destPath\n" >&2
        return 3
     fi
  fi

  is_lv ${disk}
  islv_ret=$?

  if [ ${dmsnapshot} = "yes" ] && [ "$islv_ret" == "1" ] ; then
    local vg=`get_vg ${disk}`
    local vg_dm=`double_hyphens ${vg}`
    local scriptdir=`dirname ${0}`

    if ! dmsetup info -c --noheadings -o name ${vg_dm}-${snapshotname} > /dev/null 2>&1; then
      printf "Disk ${disk} has no snapshot called ${snapshotname}.\n" >&2
      return 1
    fi

    ${qemu_img} convert -f raw -O qcow2 "/dev/mapper/${vg_dm}-${snapshotname}" "${destPath}/${destName}" || \
     ( printf "${qemu_img} failed to create backup of snapshot ${snapshotname} for disk ${disk} to ${destPath}.\n" >&2; return 2 )

  elif [ -f ${disk} ]; then
    # Does the snapshot exist?
    $qemu_img snapshot -l $disk|grep -w "$snapshotname" >& /dev/null
    if [ $? -gt 0 ]
    then
      printf "there is no $snapshotname on disk $disk\n" >&2
      return 1
    fi

    $qemu_img convert -f qcow2 -O qcow2 -s $snapshotname $disk $destPath/$destName >& /dev/null
    if [ $? -gt 0 ]
    then
      printf "Failed to backup $snapshotname for disk $disk to $destPath\n" >&2
      return 2
    fi
  else
    printf "***Failed to backup snapshot $snapshotname, undefined type $disk\n" >&2
    return 3
  fi
  return 0
}
#set -x

cflag=
dflag=
rflag=
bflag=
nflag=
pathval=
snapshot=
tmplName=
deleteDir=
dmsnapshot=no
dmrollback=no

while getopts 'c:d:r:n:b:p:t:f' OPTION
do
  case $OPTION in
  c)	cflag=1
	pathval="$OPTARG"
	;;
  d)    dflag=1
        pathval="$OPTARG"
        ;;
  r)    rflag=1
        pathval="$OPTARG"
        ;;
  b)    bflag=1
        pathval="$OPTARG"
        ;;
  n)	nflag=1
	snapshot="$OPTARG"
	;;
  p)    destPath="$OPTARG"
        ;;
  t)    tmplName="$OPTARG"
	;;
  f)    deleteDir=1
	;;
  ?)	usage
	;;
  esac
done

if modprobe dm-snapshot; then
  dmsnapshot=yes
  dmsetup targets | grep -q "^snapshot-merge" && dmrollback=yes
fi

[ -z "${snapshot}" ] && usage

[ -b "$pathval" ] && snapshot=`echo "${snapshot}" | md5sum -t | awk '{ print $1 }'`

if [ "$cflag" == "1" ]
then
  create_snapshot $pathval "$snapshot"
  exit $?
elif [ "$dflag" == "1" ]
then
  destroy_snapshot $pathval "$snapshot" $deleteDir
  exit $?
elif [ "$bflag" == "1" ]
then
  [ -z "${destPath}" -o -z "${tmplName}" ] && usage
  backup_snapshot $pathval $snapshot $destPath $tmplName
  exit $?
elif [ "$rflag" == "1" ]
then
  rollback_snapshot $pathval "$snapshot" $destPath
  exit $?
fi


exit 0
