#!/bin/bash
# Copyright (C) 2016 Ian Kelling
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# usage: mount-latest-subvol
#
# Note, at source location, intentionally not executable, run and read
# install-my-scripts.

cd /
[[ $EUID == 0 ]] || exec sudo -E "$BASH_SOURCE" "$@"

errcatch() {
  set -E; shopt -s extdebug
  _err-trap() {
    err=$?
    exec >&2
    set +x
    echo "${BASH_SOURCE[1]}:${BASH_LINENO[0]}:in \`$BASH_COMMAND' returned $err"
    bash-trace 2
    echo "$0: exiting with code $err"
    exit $err
  }
  trap _err-trap ERR
  set -o pipefail
}
bash-trace() {
  local -i argc_index=0 frame i start=${1:-1} max_indent=8 indent
  local source
  local extdebug=false
  if [[ $(shopt -p extdebug) == *-s* ]]; then
    extdebug=true
  fi

  for ((frame=0; frame < ${#FUNCNAME[@]}-1; frame++)); do
    argc=${BASH_ARGC[frame]}
    argc_index+=$argc
    ((frame < start)) && continue
    if (( ${#BASH_SOURCE[@]} > 1 )); then
      source="${BASH_SOURCE[frame+1]}:${BASH_LINENO[frame]}:"
    fi
    indent=$((frame-start+1))
    indent=$((indent < max_indent ? indent : max_indent))
    printf "%${indent}s↳%sin \`%s" '' "$source" "${FUNCNAME[frame]}"
    if $extdebug; then
      for ((i=argc_index-1; i >= argc_index-argc; i--)); do
        printf " %s" "${BASH_ARGV[i]}"
      done
    fi
    echo \'
  done
}
errcatch

tu() {
  while read -r line; do
    file="$1"
    grep -xFq "$line" "$file" || tee -a "$file"<<<"$line"
  done
}
e() { printf "%s\n" "$*"; "$@"; }
mnt() {
  dir=$1
  if ! mountpoint $dir &>/dev/null; then
    mkdir -p $dir
    e mount $dir
  fi
}
fstab() {
  while read -r start mpoint end; do
    l="$start $mpoint $end"
    # kill off any lines that duplicate the mount point.
    sed --follow-symlinks -ri "\%$l%b;\%^\s*\S+\s+$mpoint\s%d" /etc/fstab
    tu /etc/fstab <<<"$l"
  done
}
pid-check() {
  for p in ${pids}; do
    for m in ${my_pids[@]}; do
      if (( p == m )); then
        echo "$0: error: pids to kill includes our pid or a parent. ps output:" >&2
        ps -f -p $p
        exit 1
      fi
    done
  done
}
kill-dir() {
  for sig; do
    echo kill-dir $sig
    found_pids=false
    if pids=$(timeout 4 lsof -t $dir); then
      found_pids=true
      timeout 4 lsof -w $dir
      pid-check
      kill -$sig $pids
    fi
    # fuser will find open sockets that lsof won't, for example from gpg-agent.
    # note: -v shows kernel processes, which then doesn't return true when we want
    if pids=$(timeout 4 fuser -m $dir 2>/dev/null); then
      pid-check
      found_pids=true
      fuser -$sig -mvk $dir
    fi
    sleep .5
    if ! $found_pids; then
      return 0
    fi
  done
  return 1
}

force=false
if [[ $1 == -f ]]; then
  force=true
fi

ret=0

##### begin setup fstab for subvols we care about ######
root_dev=$(awk '$2 == "/" {print $1}' /etc/mtab)
if [[ $root_dev == /dev/dm-* ]]; then
  for d in /dev/mapper/*; do
    if [[ $(readlink -f $d) == $root_dev ]]; then
      root_dev=$d
      break
    fi
  done
fi

if cryptsetup status $root_dev &>/dev/null; then
  crypt_dev=$root_dev
else # if we are in a recovery boot, find the next best crypt device
  noauto=,noauto
  for dev in $(dmsetup ls --target crypt | awk '{print $1}'); do
    dev=/dev/mapper/$dev
    if awk '{print $1}' /etc/mtab | grep -Fx $dev &>/dev/null; then
      crypt_dev=$dev
      break
    fi
  done
fi


fstab <<EOF
$crypt_dev  /a  btrfs  noatime,subvol=a$noauto  0 0
EOF

shopt -s nullglob

# ssh and probably some other things care about parent directory
# ownership, and ssh doesn\'t allow any group writable parent
# directories, so we are forced to use a directory structure similar
# to home directories
f=(/mnt/root/btrbk/q.*)
if [[ -e $f ]]; then
  fstab <<EOF
$crypt_dev  /q  btrfs  noatime,subvol=q,gid=1000$noauto  0 0
/q/p  /p  none  bind$noauto  0 0
EOF
fi

f=(/mnt/root/btrbk/o.*)
if [[ -e $f ]]; then
  fstab <<EOF
$crypt_dev  /o  btrfs  noatime,subvol=o$noauto  0 0
/o/m  /m  none  bind$noauto  0 0
EOF
fi

if [[ $HOSTNAME == frodo ]]; then
  fstab <<EOF
$crypt_dev  /i  btrfs  noatime,subvol=i$noauto  0 0
EOF
fi
##### end setup fstab for subvols we care about ######

# get pids that this program depends on so we dont kill them
my_pids=($$ $PPID)
loop_limit=30
count=0
while [[ ${my_pids[-1]} != 1 && ${my_pids[-1]} != ${my_pids[-2]} && $count -lt $loop_limit  ]]; do
  count=$((count + 1))
  p=$(ps -p ${my_pids[-1]} -o ppid=)
  if [[ $p == 0 || ! $p ]]; then
    break
  fi
  my_pids+=($p)
done


for vol in q a o i; do
  d=/$vol
  if ! awk '{print $2}' /etc/fstab | grep -xF $d &>/dev/null; then
    continue
  fi


  ##### begin building up list of bind mounts  ######
  binds=() # list of bind mounts
  roots=($d) # list of bind mounts, plus the original mount
  while true; do
    new_roots=()
    for r in ${roots[@]}; do
      # eg. when r=/q/p, for lines like
      # /q/p  /p  none  bind  0 0
      # output /p
      new_roots+=($(sed -rn "s#^$r/\S+\s+(\S+)\s+none\s+bind\s.*#\1#p" /etc/fstab))
    done
    (( ${#new_roots} )) || break
    binds+=(${new_roots[@]})
    roots=( ${new_roots[@]} )
  done
  ##### end building up list of bind mounts  ######


  # if latest is already mounted, make sure binds are mounted and move on
  e check-subvol-stale $d
  # populated by check-subvol-stale if stale
  if ! fresh_snap=$(cat /nocow/btrfs-stale/$vol 2>/dev/null); then
    mnt $d
    for b in ${binds[@]}; do
      mnt $b
    done
    continue
  fi

  umount_ret=true
  unmounted=()
  for dir in $(echo $d ${binds[*]}\ |tac -s\ ); do
    if mountpoint $dir; then
      if e umount -R $dir; then
        unmounted+=($dir)
      else
        if ! kill-dir TERM TERM TERM INT INT HUP HUP; then
          if $force; then  kill-dir KILL; fi
        fi

        if e umount -R $dir; then
          unmounted+=($dir)
        else
          echo "$0: failed to umount $dir"
          umount_ret=false
          ret=1
          continue
        fi
      fi
    fi
  done

  if ! $umount_ret; then
    for dir in ${unmounted[@]}; do
      mnt $dir
    done
    continue
  fi

  # todo: decipher /mnt/root, like we do in check-subvol-stale
  cd /mnt/root
  if [[ -e $vol ]]; then
    e mv $vol $vol.leaf.$(date +%Y-%m-%dT%H:%M:%S%z)
    leaf_vols=($vol.leaf.*)
    for leaf in ${leaf_vols[@]}; do
      leaf_secs=$(date -d ${leaf#$vol.leaf.} +%s)
      if (( $(date +%s) - 60*60*24*60 > leaf_secs )); then # 60 days
        e btrfs sub del $leaf
      fi
    done
  fi
  # Note, we make a few assumptions in this script, like
  # $d was not a different subvol id than $vol, and
  # things otherwise didn't get mounted very strangely.
  e btrfs sub snapshot $fresh_snap $vol
  for dir in $d ${binds[@]}; do
    e mnt $dir
  done
  stale_dir=/nocow/btrfs-stale
  rm -f $stale_dir/$d
done

### disabled
if [[ $HOSTNAME == kdxxxxxxxxx ]]; then
  # partitioned it with fai partitioner outside of fai,
  # because it\'s worth it to have 1% space reserved for boot and
  # swap partitions in case I ever want to boot off those drives.
  # as root:
  # . /a/bin/fai/fai-wrapper
  # eval-fai-classfile /a/bin/fai/fai/config/class/51-multi-boot
  # fai-setclass ROTATIONAL
  # export LUKS_DIR=/q/root/luks/
  # # because the partition nums existed already
  # fai-setclass REPARTITION
  # /a/bin/fai/fai/config/hooks/partition.DEFAULT

  devs=(
    ata-TOSHIBA_MD04ACA500_84REK6NTFS9A-part1
    ata-TOSHIBA_MD04ACA500_84R2K773FS9A-part1
    ata-TOSHIBA_MD04ACA500_8471K430FS9A-part1
    ata-TOSHIBA_MD04ACA500_8481K493FS9A-part1
  )
  first=true
  for dev in ${devs[@]}; do
    if $first; then
      first=false
      tu /etc/fstab <<EOF
/dev/mapper/crypt_dev_$dev /i btrfs  noatime,subvol=i,noauto  0 0
/dev/mapper/crypt_dev_$dev /mnt/iroot btrfs  noatime,subvolid=0,noauto  0 0
EOF
    fi
    tu /etc/crypttab <<EOF
crypt_dev_$dev  /dev/disk/by-id/$dev  /q/root/luks/host-kd  discard,luks
EOF
    if [[ ! -e /dev/mapper/crypt_dev_$dev ]]; then
      cryptdisks_start crypt_dev_$dev
    fi
  done
  # note, could do an else here and have some kind of mount for /i
  # on other hosts.
fi

exit $ret