#!/bin/sh -e

# Copyright 2012 Slawomir Wojciech Wojtczak (vermaden). All rights reserved.
# Copyright 2012 Bryan Drewery (bdrewery). All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that following conditions are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS 'AS IS' AND ANY
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

unset LC_ALL
unset LANG
PATH=${PATH}:/bin:/usr/bin:/sbin:/usr/sbin

if [ $( uname -r | cut -d '.' -f1 ) -lt 8 ]
then
  echo "ERROR: beadm only works on FreeBSD 8.0 or later"
fi

__usage() {
  local NAME=${0##*/}
  echo "usage:"
  echo "  ${NAME} subcommand cmd_options"
  echo
  echo "  subcommands:"
  echo
  echo "  ${NAME} activate beName"
  echo "  ${NAME} create [-e nonActiveBe | beName@snapshot] beName"
  echo "  ${NAME} create beName@snapshot"
  echo "  ${NAME} destroy beName"
  echo "  ${NAME} destroy beName@snapshot"
  echo "  ${NAME} list"
  echo "  ${NAME} rename origBeName newBeName"
  exit 1
}

__be_exist() { # 1=DATASET
  if ! zfs list -H -o name ${1} 1> /dev/null 2> /dev/null
  then
    echo "ERROR: Boot environment '${1##*/}' does not exist"
    exit 1
  fi
}

__be_snapshot() { # 1=DATASET/SNAPSHOT
  echo "${1}" | grep -q "@"
}

__be_new() { # 1=SOURCE 2=TARGET
  local SOURCE=$( echo ${1} | cut -d '@' -f 1 )
  if __be_snapshot ${1}
  then
    local SNAPSHOT=$( echo ${1} | cut -d '@' -f 2 )
    zfs list -r -H -t filesystem -o name ${SOURCE} \
      | while read FS
        do
          if ! zfs list -H -o name ${FS}@${SNAPSHOT} 1> /dev/null 2> /dev/null
          then
            echo "ERROR: Child snapshot '${FS}@${SNAPSHOT}' does not exists"
            exit 1
          fi
        done
  else
    if zfs list -H -o name ${1}@${2##*/} 1> /dev/null 2> /dev/null
    then
      echo "ERROR: Snapshot '${1}@${2##*/}' already exists"
      exit 1
    fi
    if ! zfs snapshot -r ${1}@${2##*/} 1> /dev/null 2> /dev/null
    then
      echo "ERROR: Cannot create snapshot '${1}@${2##*/}'"
      exit 1
    fi
  fi
  zfs list -H -o name -r ${SOURCE} \
    | while read FS
      do
        local OPTS=""
        while read NAME PROPERTY VALUE
        do
          local OPTS="-o ${PROPERTY}=${VALUE} ${OPTS}"
        done << EOF
$( zfs get -o name,property,value -s local -H all ${FS} | grep -v -E "(canmount)" )
EOF
        DATASET=$( echo ${FS} | awk '{print $1}' | sed -E s/"^${POOL}\/ROOT\/${SOURCE##*/}"/"${POOL}\/ROOT\/${2##*/}"/g )
        if [ "${OPTS}" = "-o = " ]
        then
          local OPTS=""
        fi
        zfs clone -o canmount=off ${OPTS} ${FS}@${2##*/} ${DATASET}
      done
  echo "Created successfully"
}

ROOTFS=$( mount | awk '/ \/ / {print $1}' )

if echo ${ROOTFS} | grep -q -E "^/dev/"
then
  echo "ERROR: This system does not boot from ZFS pool"
  exit 1
fi

POOL=$( echo ${ROOTFS} | awk -F '/' '{print $1}' )

if ! zfs list ${POOL}/ROOT 1> /dev/null 2> /dev/null
then
  echo "ERROR: This system is not configured for boot environments"
  exit 1
fi

BOOTFS=$( zpool list -H -o bootfs ${POOL} )

case ${1} in

  (list) # --------------------------------------------------------------------
    POOL_PREFIX="${POOL}/ROOT"
    LIST=$( zfs list -o name,used,mountpoint,creation -s creation -H -d 1 -r ${POOL}/ROOT | grep -E "^${POOL}/ROOT/" )
    WIDTH_CREATION=$( echo "${LIST}" | awk '{print $5}' | wc -L )
    WIDTH_NAME=$( echo "${LIST}" | awk '{print $1}' | wc -L )
    WIDTH_NAME=$(( ${WIDTH_NAME} - ${#POOL_PREFIX} - 1 ))
    printf "%-${WIDTH_NAME}s %-6s %-10s %5s %6s %s\n" \
      BE Active Mountpoint Space Policy Created
    echo "${LIST}" \
      | while read NAME USED MOUNTPOINT C R E A T
        do
          NAME=${NAME##*/}
          unset ACTIVE
          if [ "${POOL_PREFIX}/${NAME}" = "${ROOTFS}" ]
          then
            ACTIVE="${ACTIVE}N"
            fi
          if [ "${POOL_PREFIX}/${NAME}" = "${BOOTFS}" ]
          then
            ACTIVE="${ACTIVE}R"
          fi
          if [ -z "${ACTIVE}" ]
          then
            ACTIVE="-"
          fi
          printf "%-${WIDTH_NAME}s %-6s " ${NAME} ${ACTIVE}
          case ${ACTIVE} in
            (N|NR) MOUNT="/" ;;
            (*)    MOUNT="-" ;;
          esac
          printf "%-10s %5s %-6s " ${MOUNT} ${USED} "static"
          date -j -f "%a %b %d %H:%M %Y" "${C} ${R} ${E} ${A} ${T}" +"%Y-%m-%d %H:%M"
        done
    ;;

  (create) # ------------------------------------------------------------------
    case ${#} in
      (4)
        if ! [ ${2} = "-e" ]
        then
          __usage
        fi
        __be_exist ${POOL}/ROOT/${3}
        if zfs list -H -o name ${POOL}/ROOT/${4} 2> /dev/null
        then
          echo "ERROR: Boot environment '${4}' already exists"
          exit 1
        fi
        __be_new ${POOL}/ROOT/${3} ${POOL}/ROOT/${4}
        ;;
      (2)
        if __be_snapshot ${2}
        then
          if ! zfs snapshot -r ${POOL}/ROOT/${2} 2> /dev/null
          then
            echo "ERROR: Cannot create '${2}' snapshot"
            exit 1
          fi
          echo "Created successfully"
        else
          __be_new ${ROOTFS} ${POOL}/ROOT/${2}
        fi
        ;;
      (*)
        __usage
        ;;
    esac
    ;;

  (activate) # ----------------------------------------------------------------
    __be_exist ${POOL}/ROOT/${2}
    if [ "${BOOTFS}" = "${POOL}/ROOT/${2}" ]
    then
      echo "Already activated"
      exit 0
    else
      if [ "${ROOTFS}" != "${POOL}/ROOT/${2}" ]
      then
        TMPMNT="/tmp/BE"
        if ! mkdir -p ${TMPMNT}
        then
          echo "ERROR: Cannot create '${TMPMNT}' directory"
          exit 1
        fi
        MOUNT=0
        while read FS MNT
        do
          if [ "${FS}" = "${POOL}/ROOT/${2}" ]
          then
            MOUNT=${MNT}
          fi
        done << EOF
$( mount -p | awk '{print $1 " " $2}' )
EOF
        if [ ${MOUNT} -eq 0 ]
        then
          zfs set canmount=noauto ${POOL}/ROOT/${2}
          zfs set mountpoint=${TMPMNT} ${POOL}/ROOT/${2}
          zfs mount ${POOL}/ROOT/${2} 1> /dev/null 2> /dev/null
        else
          TMPMNT=${MOUNT}
        fi
        cp /boot/zfs/zpool.cache ${TMPMNT}/boot/zfs/zpool.cache # 2> /dev/null
        LOADER_CONFIGS=${TMPMNT}/boot/loader.conf
        if [ -f ${TMPMNT}/boot/loader.conf.local ]
        then
          LOADER_CONFIGS="${LOADER_CONFIGS} ${TMPMNT}/boot/loader.conf.local"
          fi
        sed -i '' -E s/"^vfs.root.mountfrom=.*$"/"vfs.root.mountfrom=\"zfs:${POOL}\/ROOT\/${2##*/}\""/g ${LOADER_CONFIGS} 2> /dev/null
        if [ ${MOUNT} -eq 0 ]
        then
          zfs umount ${POOL}/ROOT/${2}
          zfs set mountpoint=legacy ${POOL}/ROOT/${2}
        fi
      fi
      if ! zpool set bootfs=${POOL}/ROOT/${2} ${POOL}
      then
        echo "ERROR: Failed to activate '${POOL}/ROOT/${2}'"
        exit 1
      fi
    fi
    # Disable mounting on all inactive datasets
    zfs list -H -o name -r ${POOL}/ROOT \
      | grep -v "${POOL}/ROOT/${2}" \
      | while read I
        do
          zfs set canmount=noauto ${I}
        done
    # Enable mounting for the active BE and promote it
    zfs list -H -o name -t filesystem -r ${POOL}/ROOT/${2} \
      | while read I
        do
          zfs set canmount=on ${I} 2> /dev/null
          zfs promote ${I} 2> /dev/null
        done
    echo "Activated successfully"
    ;;

  (destroy) # ----------------------------------------------------------------
    __be_exist ${POOL}/ROOT/${2}
    if [ "${BOOTFS}" = "${POOL}/ROOT/${2}" ]
    then
      echo "ERROR: '${POOL}/ROOT/${2}' is current active boot environment"
      exit 1
    fi
    echo "Are you sure you want to destroy '${2}'?"
    echo -n "This action cannot be undone (y/[n]): "
    read CHOICE
    case ${CHOICE} in
      (Y|y|[Yy][Ee][Ss])
        if __be_snapshot ${POOL}/ROOT/${2}
        then
          if ! zfs destroy -r ${POOL}/ROOT/${2} 1> /dev/null 2> /dev/null
          then
            echo "ERROR: Snapshot '${2}' is origin for other boot environment(s)"
            exit 1
          fi
        else
          ORIGINS=$( zfs list -r -H -o origin ${POOL}/ROOT/${2} )
          if ! zfs destroy ${POOL}/ROOT/${2} 1> /dev/null 2> /dev/null
          then
            zfs destroy -r ${POOL}/ROOT/${2} 2>&1 \
              | grep "${POOL}/ROOT/" \
              | grep -v "@" \
              | while read I
                do
                  zfs promote ${I} 2> /dev/null
                done
          fi
          if ! [ "${ORIGINS}" = "-" ]
          then
            echo "${ORIGINS}" \
              | while read I
                do
                  zfs destroy -r ${I} 2> /dev/null
                done
          fi
        fi
        echo "Destroyed successfully"
        ;;
      (*)
        echo "'${2}' has not been destroyed"
        ;;
    esac
    ;;

  (rename) # ------------------------------------------------------------------
    __be_exist ${POOL}/ROOT/${2}
    if zfs list -H -o name ${POOL}/ROOT/${3} 2> /dev/null
    then
      echo "ERROR: Boot environment '${3}' already exists"
      exit 1
    fi
    zfs rename ${POOL}/ROOT/${2} ${POOL}/ROOT/${3}
    echo "Renamed successfully"
    ;;

  (*) # -----------------------------------------------------------------------
    __usage
    ;;
esac