# 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"
}

# Install a default $1/etc/network/interfaces on the subhost root $1
setup_networking() {
    [ -r $1/etc/network/interfaces ] && return 0
    mkdir -p $1/etc/network
    cat <<EOF >> $1/etc/network/interfaces
# Generated for $NAME subhost
auto lo
iface lo inet loopback
EOF
    for IF in $(ip netns exec $NAME ip link show | grep "^eth") ; do
	cat <<EOF >> $1/etc/network/interfaces

auto eth$i
iface eth$i inet manual
EOF
    done
}

# 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="$1"
    shift 1
    i=0
    for C in "$@" ; 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 $IF up
	BR="${C%=*}"
	if [ -z "$BR" ] ; then
	    ip link set $IF
	    ifup $IF
	else
	    brctl addif $BR $IF
	fi
	i=$((i+1))
    done
}

# (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 LIVE="$2" LOWER="$3" UPPER="$4" ROOT

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

    if [ -f "${UPPER%% *}" ] ; then
	if [ -x "${UPPER%% *}" ] ; then
	    echo "${UPPER%% *} appears to be executable" >&2
	    # Giving a program/script as UPPER= asks for running this
	    # first, to make a root filesystem available. The script takes
	    # ACTION "setup" and "teardown", and on "setup" it must tell
	    # where the ROOT is set up.
	    ROOT="$(env ACTION=setup $UPPER)"
	    if [ ! -d "$ROOT" ] ; then
		# setup failed
		die "root setup failed: $UPPER"
	    fi
	    UPPER="$ROOT"
	    ## Now falling down to "normal overlay" setup
	else
	    die "${UPPER%% *} (root setup program/script) is not executable"
	fi
    fi

    # LIVE is the same as LOWER then skip the overlay; just assume
    # a proper chroot system exists at LIVE.
    if [ "$LIVE" != "$LOWER" ] ; then
	# sanity check
	[ -d "$WORK" ] || die "WORK=$WORK is not a directory"
	[ -d "$UPPER" ] || die "UPPER=$UPPER is not a directory"
	[ -d "$LOWER" ] || die "LOWER=LOWPER is not a directory"
	[ -d "$LIVE" ] || die "LOWER=LOWPER is not a directory"
	# setup $UPPER/dev
	mkdir -p "$UPPER/dev"
	mount -t tmpfs -osize=50M tmpfs "$UPPER/dev"
	mknod -m 622 "$UPPER/dev/console" c 5 1
	mknod -m 666 "$UPPER/dev/null" c 1 3
	mknod -m 666 "$UPPER/dev/zero" c 1 5
	mknod -m 666 "$UPPER/dev/ptmx" c 5 2
	mknod -m 666 "$UPPER/dev/tty" c 5 0
	mknod -m 444 "$UPPER/dev/random" c 1 8
	mknod -m 444 "$UPPER/dev/urandom" c 1 9
	chown root:tty "$UPPER/dev/console"
	chown root:tty "$UPPER/dev/ptmx"
	chown root:tty "$UPPER/dev/tty"
	ln -sTf /proc/self/fd "$UPPER/dev/fd"
	ln -sTf /proc/self/fd/0 "$UPPER/dev/stdin"
	ln -sTf /proc/self/fd/1 "$UPPER/dev/stdout"
	ln -sTf /proc/self/fd/2 "$UPPER/dev/stderr"
	ln -sTf /proc/kcore "$UPPER/dev/core"
	mkdir "$UPPER/dev/shm"
	mkdir "$UPPER/dev/pts"
	chmod 1777 "$UPPER/dev/shm"

	# all good so far ; now avoid using the host's networking setup
	setup_networking "$UPPER"

	OLY="-olowerdir=$3,upperdir=$UPPER,workdir=$5"
	if ! mount -t overlay "$OLY" $1 $2 ; then
	    umount -R "$UPPER/dev"
	    umount "$UPPER/run"
	    die "Cannot set up the overlay mount $2"
	fi
    fi

    echo "Installing $OVERLAYDIR/reaper to $LIVE/.reaper"
    cp -p $OVERLAYDIR/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")
}

list_running() {
    for C in $(pgrep -a overlay-boot | awk '{print $4}') ; do
	eval NAME="$(sed "/^NAME=.*/{s|^NAME=||;b};d" $C)"
	[ -z "$NAME" ] && NAME=$(basename $C .conf)
	echo $NAME
    done
}