zrokdir versioning (#134)

zrokdir/version.go

@@ -0,0 +1,47 @@
+package zrokdir
+
+import (
+	"encoding/json"
+	"github.com/pkg/errors"
+	"os"
+)
+
+const V = "v0.3"
+
+type Metadata struct {
+	V string `json:"v"`
+}
+
+func checkMetadata() error {
+	mf, err := metadataFile()
+	if err != nil {
+		return err
+	}
+	data, err := os.ReadFile(mf)
+	if err != nil {
+		return errors.Wrapf(err, "error reading metadata file '%v'", mf)
+	}
+	m := &Metadata{}
+	if err := json.Unmarshal(data, m); err != nil {
+		return errors.Wrapf(err, "error unmarshaling metadata file '%v'", mf)
+	}
+	if m.V != V {
+		return errors.Errorf("invalid zrokdir metadata version '%v'", m.V)
+	}
+	return nil
+}
+
+func writeMetadata() error {
+	mf, err := metadataFile()
+	if err != nil {
+		return err
+	}
+	data, err := json.Marshal(&Metadata{V: V})
+	if err != nil {
+		return err
+	}
+	if err := os.WriteFile(mf, data, os.FileMode(0400)); err != nil {
+		return err
+	}
+	return nil
+}

zrokdir/zrokdir.go

@@ -36,6 +36,10 @@ func Initialize() (*ZrokDir, error) {
 }
 
 func Load() (*ZrokDir, error) {
+	if err := checkMetadata(); err != nil {
+		return nil, err
+	}
+
 	zrd := &ZrokDir{}
 
 	ids, err := listIdentities()
@@ -72,6 +76,9 @@ func Load() (*ZrokDir, error) {
 }
 
 func (zrd *ZrokDir) Save() error {
+	if err := writeMetadata(); err != nil {
+		return errors.Wrap(err, "error saving metadata")
+	}
 	if zrd.Env != nil {
 		if err := saveEnvironment(zrd.Env); err != nil {
 			return errors.Wrap(err, "error saving environment")
@@ -147,6 +154,14 @@ func identitiesDir() (string, error) {
 	return filepath.Join(zrd, "identities"), nil
 }
 
+func metadataFile() (string, error) {
+	zrd, err := zrokDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(zrd, "metadata.json"), nil
+}
+
 func zrokDir() (string, error) {
 	home, err := os.UserHomeDir()
 	if err != nil {