# This file implements common functions for all boot methods

die() {
    echo "$*" >&2
    exit 1
}

# grab and set a configuration variable
# $1 = variable, [ $2 = default .. error otherwise ]
config() {
    eval $1="$(sed "/^$1=.*/{s|^$1=||;b};d" $CONFIG)"
    [ -z "$(eval echo "\$$1")" ] || return 0
    [ $# -lt 2 ] && die "Missing $1=... in $CONFIG"
    eval $1="'$2'"
    eval echo "$1=\$$1"
}

# Unless the subhost already has a private /etc/network/interfaces,
# install an "empty" one
setup_networking() {
    [ -r $UPPER/etc/network/interfaces ] && return 0
    [ "$UPPER/etc/network" = "/etc/network" ] && exit 1
    mkdir -p $UPPER/etc/network
    cat <<EOF > $UPPER/etc/network/interfaces
# Generated for $NAME subhost
auto lo
iface lo inet loopback
EOF
    return 1
}

# Setup the network namespace for the given $CABLES
# $1=netns ( $2="br=mac" .. )
setup_veth_cables() {
    local NETNS BR IF MAC C i ADD
    NETNS="$1"
    shift 1
    i=0
    ADD=false
    setup_networking || ADD=true
    for C in "$@" ; do
	IF=$NETNS$i
	MAC="${C#*=}"
	[ -z "$MAC" ] || MAC="address $MAC"
	ip link add $IF type veth peer name eth$i $MAC netns $NETNS
	ip link set $IF up
	$ADD && cat <<EOF >> $UPPER/etc/network/interfaces

auto eth$i
iface eth$i inet manual
EOF
	BR="${C%=*}"
	[ -z "$BR" ] || brctl addif $BR $IF
	i=$((i+1))
    done
}

REAPER=$(dirname $(realpath $0))/reaper
# (name live system root work)
# Set up an overlay fmr $name on $live, with a new tmpfs on its /run,
# and "install" a "reaper" as the upcoming pid 1
setup_overlay() {
    local ROOT="$4"
    local LIVE="$2"

    if grep -q "$1 $2" /proc/mounts ; then
	die "$1 is already mounted"
    fi

    # setup $ROOT/run
    mkdir -p "$ROOT/run"
    mount -t tmpfs -osize=100M tmpfs "$ROOT/run"
    mkdir -p "$ROOT/run/lock"
    # setup $ROOT/dev
    mkdir -p "$ROOT/dev"
    mount -t tmpfs -osize=100M tmpfs "$ROOT/dev"
    mknod -m 622 "$ROOT/dev/console" c 5 1
    mknod -m 666 "$ROOT/dev/null" c 1 3
    mknod -m 666 "$ROOT/dev/zero" c 1 5
    mknod -m 666 "$ROOT/dev/ptmx" c 5 2
    mknod -m 666 "$ROOT/dev/tty" c 5 0
    mknod -m 444 "$ROOT/dev/random" c 1 8
    mknod -m 444 "$ROOT/dev/urandom" c 1 9
    chown root:tty "$ROOT/dev/console"
    chown root:tty "$ROOT/dev/ptmx"
    chown root:tty "$ROOT/dev/tty"
    ln -sTf /proc/self/fd "$ROOT/dev/fd"
    ln -sTf /proc/self/fd/0 "$ROOT/dev/stdin"
    ln -sTf /proc/self/fd/1 "$ROOT/dev/stdout"
    ln -sTf /proc/self/fd/2 "$ROOT/dev/stderr"
    ln -sTf /proc/kcore "$ROOT/dev/core"
    mkdir "$ROOT/dev/shm"
    mkdir "$ROOT/dev/pts"
    chmod 1777 "$ROOT/dev/shm"

    if mount -t overlay -olowerdir=$3,upperdir=$4,workdir=$5 $1 $2 ; then
	: # all good
    else
	umount -R "$ROOT/dev"
	umount "$ROOT/run"
	die "Cannot set up the overlay mount $2"
    fi
    cp -p $REAPER $LIVE/.reaper
}

start_services() {
    for S in "$@" ; do
	service $S start
    done
}

# find the upperdir option for an overlay mount line
getupper() {
    sed 's/.*upperdir=\([^,]*\).*/\1/'
}

# Check if $1 is "live" and echo the
# unshare and reaper process pids
is_live() {
    local NAME=$1
    local USPID="$(pgrep -f "unshare.* $NAME ")"
    [ -z "$USPID" ] && return 1
    echo $USPID $(pgrep -f ".reaper $NAME")
}