Initial commit.

watchman-svc.bash

@@ -0,0 +1,150 @@
+#!@BASH_PATH@
+
+watchman_version='@VERSION@'
+
+msg() { printf '%s\n' "$*"; }
+err() { printf '%s\n' "$*" >&2; }
+
+usage() {
+	while read; do msg "$REPLY"; done <<- 'EOF'
+		Usage: watchman-svc <-p pidfile> [options] command
+		Flags:
+		       -p <pidfile>
+		       -l <logfile>
+		       -r           # Respawn the process if it dies.
+		       -h           # Show this message.
+		       -v           # Show version.
+	EOF
+}
+
+cleanup() {
+	for i in "$respawn_pid" "$job_pid"; do
+		kill_wait "$i" || {
+			err "Failed to stop child: $i"
+			exit 13
+		}
+	done
+
+	rm -f "$job_pidfile"
+}
+
+respawn_cleanup() {
+	kill_wait "$job_pid" || {
+		err "Failed to stop child: $i"
+		exit 13
+	}
+
+	return 0
+}
+
+respawn_passthrough() {
+	kill -"$1" "$job_pid"
+}
+
+kill_wait() {
+	kill "$1" &>/dev/null
+
+	counter=0
+	while kill -0 "$1" &>/dev/null; do
+		sleep 1
+		(( counter >= 10 )) && { return 1; }
+		(( counter++ ))
+	done
+
+	return 0
+}
+
+job_run() {
+	"${cmd[@]}" >&3 2>&3 & job_pid=$!
+	export job_pid
+	return 0
+}
+
+
+job_respawn() {
+	trap 'respawn_cleanup; return' INT TERM
+
+	trap 'respawn_passthrough 1' HUP
+	trap 'respawn_passthrough 10' USR1
+	trap 'respawn_passthrough 12' USR2
+
+	while job_run; do
+		last_run=$SECONDS
+		if kill -0 "$job_pid"; then
+			wait "$job_pid"
+		fi
+
+		curtime=$SECONDS
+		if (( last_run + 1 > ( curtime - 2 ) )); then
+			err "The job exists right as we start it. Bailing."
+			return 1
+		fi
+	done
+}
+
+job_wait() {
+	trap cleanup INT TERM
+
+	if (( flag_respawn )); then
+		job_respawn & respawn_pid=$!
+		
+		printf '%s' "$respawn_pid" > "$job_pidfile"
+
+		wait "$respawn_pid"
+	else
+		job_run
+
+		printf '%s' "$job_pid" > "$job_pidfile"
+
+		wait "$job_pid"
+	fi
+
+	cleanup
+}
+
+main() {
+	while (( $# )); do
+		case "$1" in
+			(-h) usage; return 0;;
+
+			(-p) job_pidfile="$2"; shift;;
+			(-l) job_logfile="$2"; shift;;
+
+			(-r) flag_respawn=1;;
+
+			(-v)
+				printf '%s\n' "$watchman_version"
+				exit 0
+			;;
+
+			(--) shift; break;;
+			(-*)
+				err "Unknown key: $1"
+				usage
+				return 1
+			;;
+
+			(*) break;;
+		esac
+		shift
+	done
+
+	if [[ -z "$job_pidfile" ]]; then
+		usage
+		return 1
+	fi
+
+	cmd=( "$@" )
+
+	if [[ "$job_logfile" ]]; then
+		exec 3>"$job_logfile"
+	else
+		exec 3>&1
+	fi
+
+	job_wait &
+
+	return 0
+}
+
+main "$@"