go rewrite

internal/lock/lock.go

@@ -0,0 +1,52 @@
+package lock
+
+import (
+	"errors"
+	"path"
+	"sync"
+
+	"github.com/spf13/viper"
+)
+
+var lock *viper.Viper
+var file string
+var once sync.Once
+
+func getLock() *viper.Viper {
+	if lock == nil {
+
+		once.Do(func() {
+			lock = viper.New()
+			lock.SetDefault("running", false)
+			p := path.Dir(viper.ConfigFileUsed())
+			file = path.Join(p, ".autorestic.lock.yml")
+			lock.SetConfigFile(file)
+			lock.SetConfigType("yml")
+			lock.ReadInConfig()
+		})
+	}
+	return lock
+}
+
+func set(locked bool) error {
+	lock := getLock()
+	if locked {
+		running := lock.GetBool("running")
+		if running {
+			return errors.New("an instance is already running")
+		}
+	}
+	lock.Set("running", locked)
+	if err := lock.WriteConfigAs(file); err != nil {
+		return err
+	}
+	return nil
+}
+
+func Lock() error {
+	return set(true)
+}
+
+func Unlock() error {
+	return set(false)
+}