refactor: add platform

internal/platform/droppriv_nope.go

@@ -0,0 +1,13 @@
+//go:build linux || windows
+// +build linux windows
+
+package platform
+
+import (
+	"errors"
+	"runtime"
+)
+
+func DropPrivileges(uid, gid int) error {
+	return errors.New("setuid and setgid not supported on " + runtime.GOOS)
+}

internal/platform/droppriv_unix.go

@@ -0,0 +1,22 @@
+//go:build !windows && !linux
+// +build !windows,!linux
+
+package platform
+
+import (
+	"syscall"
+)
+
+func DropPrivileges(uid, gid int) error {
+	err := syscall.Setgid(gid)
+	if err != nil {
+		return err
+	}
+
+	err = syscall.Setuid(uid)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

internal/platform/signals.go

@@ -0,0 +1,55 @@
+//go:build !windows
+// +build !windows
+
+package platform
+
+import (
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/adnanh/webhook/internal/pidfile"
+)
+
+func SetupSignals(signals chan os.Signal, reloadFn func(), pidFile *pidfile.PIDFile) {
+	log.Printf("setting up os signal watcher\n")
+
+	signals = make(chan os.Signal, 1)
+	signal.Notify(signals, syscall.SIGUSR1)
+	signal.Notify(signals, syscall.SIGHUP)
+	signal.Notify(signals, syscall.SIGTERM)
+	signal.Notify(signals, os.Interrupt)
+
+	go watchForSignals(signals, reloadFn, pidFile)
+}
+
+func watchForSignals(signals chan os.Signal, reloadFn func(), pidFile *pidfile.PIDFile) {
+	log.Println("os signal watcher ready")
+
+	for {
+		sig := <-signals
+		switch sig {
+		case syscall.SIGUSR1:
+			log.Println("caught USR1 signal")
+			reloadFn()
+
+		case syscall.SIGHUP:
+			log.Println("caught HUP signal")
+			reloadFn()
+
+		case os.Interrupt, syscall.SIGTERM:
+			log.Printf("caught %s signal; exiting\n", sig)
+			if pidFile != nil {
+				err := pidFile.Remove()
+				if err != nil {
+					log.Print(err)
+				}
+			}
+			os.Exit(0)
+
+		default:
+			log.Printf("caught unhandled signal %+v\n", sig)
+		}
+	}
+}

internal/platform/signals_windows.go

@@ -0,0 +1,8 @@
+//go:build windows
+// +build windows
+
+package platform
+
+func SetupSignals() {
+	// NOOP: Windows doesn't have signals equivalent to the Unix world.
+}