From 8aa9cfbf6f0dbc1a4ed2d63c05b096e53f57ca6b Mon Sep 17 00:00:00 2001
From: Dan Fuhry <dan@fuhry.com>
Date: Thu, 25 Apr 2024 00:09:13 -0400
Subject: [PATCH] machines agent: initial support for openbsd pid-file services

---
 machines/machines_agent/main.go |   4 +
 machines/services_openbsd.go    | 181 ++++++++++++++++++++++++++++++++
 2 files changed, 185 insertions(+)
 create mode 100644 machines/services_openbsd.go

diff --git a/machines/machines_agent/main.go b/machines/machines_agent/main.go
index dba82d8..08efb19 100644
--- a/machines/machines_agent/main.go
+++ b/machines/machines_agent/main.go
@@ -169,6 +169,10 @@ mainLoop:
 
 			for _, svcName := range svcs {
 				svc := machines.GetService(svcName)
+				if svc == nil {
+					logger.Warningf("failed to get service %v: not supported on this platform", svcName)
+					continue
+				}
 				if err := svc.ReloadOrRestart(false); err != nil {
 					logger.Warningf("failed to restart service %+v: %v", svcName, err)
 					serviceRestarts.WithLabelValues(mbclient.KV{"service": svcName, "status": "failed"}).Add(1)
diff --git a/machines/services_openbsd.go b/machines/services_openbsd.go
new file mode 100644
index 0000000..3ceb26d
--- /dev/null
+++ b/machines/services_openbsd.go
@@ -0,0 +1,181 @@
+//go:build openbsd
+
+package machines
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+)
+
+type pidFileService struct {
+	executable string
+	arguments  []string
+	pidFile    string
+	daemon     bool
+}
+
+const serviceStartTimeout = 10 * time.Second
+const serviceStopTimeout = 10 * time.Second
+
+func (s *pidFileService) EnsureStarted() error {
+	status, err := s.Status()
+	if err != nil {
+		return err
+	}
+
+	if status.Running {
+		return nil
+	}
+
+	args := make([]string, len(s.arguments)+1)
+	args[0] = s.executable
+	copy(args[1:], s.arguments)
+	logger.V(2).Debugf("starting process: %+v", args)
+
+	attrs := &os.ProcAttr{
+		Dir: "/",
+		Env: []string{},
+		Files: []*os.File{
+			os.Stdin,
+			os.Stdout,
+			os.Stderr,
+		},
+	}
+
+	startDeadline := time.Now().Add(serviceStartTimeout)
+	proc, err := os.StartProcess(s.executable, args, attrs)
+	if err != nil {
+		return err
+	}
+
+	if s.daemon {
+		defer proc.Wait()
+	} else {
+		defer proc.Release()
+	}
+	for {
+		if time.Now().After(startDeadline) {
+			return fmt.Errorf("failed to start process after %v seconds: %v", serviceStartTimeout, args)
+		}
+
+		status, err := s.Status()
+		if err == nil && status.Running {
+			logger.V(2).Debugf("process started in %v", time.Now().Add(serviceStartTimeout).Sub(startDeadline))
+			return nil
+		}
+
+		time.Sleep(serviceStartTimeout / 100)
+	}
+}
+
+func (s *pidFileService) EnsureStopped() error {
+	status, err := s.Status()
+	if err != nil {
+		return err
+	}
+	if !status.Running {
+		return nil
+	}
+
+	proc, err := os.FindProcess(status.Pid)
+	if err != nil {
+		return err
+	}
+
+	signal := syscall.SIGTERM
+	logger.V(2).Infof("sending signal %v to pid %d", signal, status.Pid)
+	proc.Signal(signal)
+	stopDeadline := time.Now().Add(serviceStartTimeout)
+	for {
+		err := proc.Signal(syscall.Signal(0))
+		if err != nil {
+			logger.V(2).Infof("pid %d now appears to be dead", status.Pid)
+			proc.Wait()
+			os.Remove(s.pidFile)
+			return nil
+		}
+		if time.Now().After(stopDeadline) {
+			if signal == syscall.SIGTERM {
+				signal = syscall.SIGKILL
+				logger.V(2).Infof("sending signal %v to pid %d", signal, status.Pid)
+				proc.Signal(signal)
+				stopDeadline = time.Now().Add(serviceStartTimeout)
+			} else {
+				return fmt.Errorf("failed to kill pid %d", status.Pid)
+			}
+		}
+		time.Sleep(serviceStartTimeout / 100)
+	}
+}
+
+func (s *pidFileService) ReloadOrRestart(startIfStopped bool) error {
+	status, err := s.Status()
+	if err != nil {
+		return err
+	}
+	if !status.Running && !startIfStopped {
+		return nil
+	}
+
+	if status.Running {
+		if err := s.EnsureStopped(); err != nil {
+			return err
+		}
+	}
+
+	return s.EnsureStarted()
+}
+
+func (s *pidFileService) Status() (*ServiceStatus, error) {
+	st := &ServiceStatus{}
+
+	logger.V(2).Debugf("read pid file: %s", s.pidFile)
+	pidContents, err := os.ReadFile(s.pidFile)
+	if err != nil {
+		return st, nil
+	}
+
+	pidStr := strings.TrimSpace(string(pidContents))
+	pid, err := strconv.Atoi(pidStr)
+	if err != nil {
+		return st, nil
+	}
+	logger.V(2).Debugf("got pid: %d", pid)
+
+	proc, err := os.FindProcess(pid)
+	if err != nil {
+		return st, nil
+	}
+	defer proc.Release()
+
+	logger.V(2).Debugf("sending signal NULL to pid %d", pid)
+	err = proc.Signal(syscall.Signal(0))
+	if err == nil {
+		logger.V(2).Debugf("pid %d is alive", pid)
+		st.Running = true
+		st.Pid = pid
+	} else {
+		logger.V(2).Debugf("pid %d not alive: %v", pid, err)
+	}
+
+	return st, nil
+}
+
+func init() {
+	registerService("dhcpd4", &pidFileService{
+		executable: "/usr/local/sbin/dhcpd",
+		arguments:  []string{"-q", "-pf", "/var/run/dhcpd.pid", "-cf", "/etc/dhcpd4.conf"},
+		pidFile:    "/var/run/dhcpd.pid",
+		daemon:     true,
+	})
+	registerService("dhcpd6", &pidFileService{
+		executable: "/usr/local/sbin/dhcpd",
+		arguments:  []string{"-6", "-q", "-pf", "/var/run/dhcpd6.pid", "-cf", "/etc/dhcpd6.conf"},
+		pidFile:    "/var/run/dhcpd6.pid",
+		daemon:     true,
+	})
+}
-- 
2.50.1