feat(stdlib): began adding systemd services support

stdlib/os/systemd/systemd.go

@@ -0,0 +1,70 @@
+package systemd
+
+import (
+	"errors"
+	"os/exec"
+
+	"git.adyxax.org/adyxax/gonf/v2/gonf"
+)
+
+func Promise() {
+	gonf.SetServiceFunction(systemd_service)
+}
+
+func isEnabled(name string) bool {
+	return systemctlShow(name, "UnitFileState") == "enabled"
+}
+
+func isRunning(name string) bool {
+	return systemctlShow(name, "SubState") == "running"
+}
+
+func systemctl(name, operation string) (gonf.Status, error) {
+	cmd := exec.Command("systemctl", operation, name)
+	if err := cmd.Run(); err != nil {
+		return gonf.BROKEN, err
+	}
+	return gonf.REPAIRED, nil
+}
+
+func systemctlShow(name, field string) string {
+	ecmd := exec.Command("systemctl", "show", name, "-p", field, "--value")
+	out, _ := ecmd.CombinedOutput()
+	return string(out[:len(out)-1]) // remove trailing '\n' and convert to string
+}
+
+func systemd_service(name, state string) (gonf.Status, error) {
+	switch state {
+	case "disabled":
+		if isEnabled(name) {
+			return systemctl(name, "disable")
+		} else {
+			return gonf.KEPT, nil
+		}
+	case "enabled":
+		if isEnabled(name) {
+			return gonf.KEPT, nil
+		} else {
+			return systemctl(name, "enable")
+		}
+	case "reloaded":
+		return systemctl(name, "reloaded")
+	case "restarted":
+		return systemctl(name, "restart")
+	case "started":
+		if isRunning(name) {
+			return gonf.KEPT, nil
+		} else {
+			return systemctl(name, "start")
+		}
+	case "stopped":
+		if isRunning(name) {
+			return systemctl(name, "stop")
+		} else {
+			return gonf.KEPT, nil
+		}
+	default:
+		return gonf.BROKEN, errors.New("unsupported systemctl operation " + state)
+	}
+	return gonf.KEPT, nil
+}