#!/bin/sh
die()
{
    printf '%s\n' "$*" >&2
    exit 1
}

target=$1

if [ ! "$target" ] && mountpoint -q /srv && [ ! -e /srv/samizdat.iso ]; then
    target=/srv/samizdat.iso
fi

[ "$target" ] || die "Usage: $0 <target filename>"
[ ! -e "$target" ] || die "Error: file exists: $target"

if mountpoint -q /outerfs; then
    temp_target=$(mktemp --tmpdir=/outerfs)
else
    die "Error: /outerfs is not a mountpoint.  Please mount a safe filesystem to temporarily store the ISO on /outerfs"
fi

. mdadm-dup.sh || exit 1

btrfs_subdevices()
{
    local mountpoint="$1"
    btrfs filesystem show "$mountpoint" | sed -ne 's/^[ \t]*devid.* path //p'
}

devices=$(btrfs_subdevices /) || exit 1

set --
seen=
for dev in $devices; do
    [ -b "$dev" ] || exit 1
    case "$dev" in
        /dev/mapper/loop*) set -- "$@" "$dev" ;;
        /dev/mapper/samizdatcrypt) seen=y ;;
    esac
done
[ "$seen" ] || set -- # avoid messing up someone's btrfs!

copy()
{
    mdadm_copy_eject_crypt /dev/md55 "$temp_target" &&
        mdadm_copy_eject /dev/md55 "$target".part &&
        mv "$target".part "$target"
}

remove()
{
    for dev; do
        (set -x; btrfs device remove "$dev" /)
        dmsetup remove "$dev" 2>/dev/null
        losetup -D
    done
}

# Doing the mdadm copy before removing the devices means our filesystem includes
# devices that are ultimately backed by files ON THE SAME FILESYSTEM. As such, it
# might conceivably put btrfs into a deadlock of some kind.

# If it turns out this doesn't work, the order can be reversed. This will
# perform the read IO twice, though, almost doubling the total installation
# time.

copy & remove "$@"

set -x
wait