#!/bin/sh
# Keep daed as a child so signals can be forwarded and stale netns/veth
# state can be cleaned before start and after exit. daed owns TC detach;
# /sys/fs/bpf/daed is normal persistent state and is never removed here.

. /usr/share/daed/cleanup.sh

# Pre-start cleanup refuses to remove runtime state while another
# daed instance is active, and fails closed if that probe is broken.
DAED_GUARD_CLEANUP=start
if ! daed_cleanup_runtime; then
	echo "daed: stale /usr/bin/daed or netns state could not be verified or removed; refusing to start. Check process and netns state." >&2
	logger -t daed-init "pre-start cleanup failed: refusing to start daed"
	exit 1
fi

# Keep daed as a child so post-exit cleanup runs before procd can
# respawn it.
child_pid=
pending_signal=
shutdown_signal=
shutdown_elapsed=0
forced_kill=0
child_term_timeout=20

forward_signal() {
	local sig="$1"
	if [ -z "$child_pid" ]; then
		pending_signal="$sig"
		logger -t daed-init "signal $sig received before daed child started; launch cancelled"
		return 0
	fi
	case "$sig" in
		TERM|INT|QUIT)
			if [ -z "$shutdown_signal" ]; then
				shutdown_signal="$sig"
				shutdown_elapsed=0
			fi
			;;
	esac
	kill -"$sig" "$child_pid" 2>/dev/null
}

exit_with_signal() {
	local sig="$1"
	trap - TERM INT HUP QUIT
	kill -"$sig" "$$" 2>/dev/null
	exit 1
}

child_is_running() {
	local state
	kill -0 "$child_pid" 2>/dev/null || return 1
	state=$(awk '{ print $3 }' "/proc/$child_pid/stat" 2>/dev/null)
	[ "$state" != "Z" ]
}
trap 'forward_signal TERM' TERM
trap 'forward_signal INT' INT
trap 'forward_signal HUP' HUP
trap 'forward_signal QUIT' QUIT

start_child() {
	local sig
	# Keep this check inside the function as well as at the call site:
	# it closes the ordinary pre-start window, while the pending-signal
	# path below handles a signal arriving during the background fork.
	[ -z "$pending_signal" ] || return 125
	/usr/bin/daed "$@" &
	child_pid=$!
	if [ -n "$pending_signal" ]; then
		sig="$pending_signal"
		pending_signal=
		forward_signal "$sig"
	fi
}

if [ -n "$pending_signal" ]; then
	logger -t daed-init "refusing to start daed after pending signal $pending_signal"
	exit_with_signal "$pending_signal"
fi

# Best-effort OOM preference; failure must not block startup.
if ! echo -16 > /proc/self/oom_score_adj 2>/dev/null; then
	logger -t daed-init "warn: failed to set /proc/self/oom_score_adj; continuing without OOM preference"
fi
if ! start_child "$@"; then
	logger -t daed-init "refusing to start daed after pending signal $pending_signal"
	if [ -n "$pending_signal" ]; then
		exit_with_signal "$pending_signal"
	fi
	exit 1
fi
status=0
reaped=0
while [ "$reaped" -eq 0 ]; do
	if [ -n "$shutdown_signal" ] && child_is_running; then
		if [ "$shutdown_elapsed" -ge "$child_term_timeout" ]; then
			if [ "$forced_kill" -eq 0 ]; then
				logger -t daed-init "daed did not exit within ${child_term_timeout}s after $shutdown_signal; sending KILL"
				kill -KILL "$child_pid" 2>/dev/null
				forced_kill=1
			fi
		else
			sleep 1
			shutdown_elapsed=$((shutdown_elapsed + 1))
			continue
		fi
		sleep 1
		continue
	fi
	wait "$child_pid" 2>/dev/null
	status=$?
	if ! child_is_running; then
		reaped=1
	fi
done
child_pid=
trap - TERM INT HUP QUIT

# Post-exit cleanup runs after the child is reaped.
DAED_GUARD_CLEANUP=post-exit
cleanup_status=0
daed_cleanup_runtime || cleanup_status=$?
if [ "$cleanup_status" -ne 0 ]; then
	echo "daed: runtime cleanup after exit failed" >&2
	logger -t daed-init "post-exit cleanup failed; check ip netns / ip link show"
fi
if [ "$status" -ne 0 ]; then
	exit "$status"
fi
exit "$cleanup_status"