terraform: Guard against future version changes

terraform/state.go

@@ -533,6 +533,12 @@ func ReadState(src io.Reader) (*State, error) {
 		return nil, fmt.Errorf("Decoding state file failed: %v", err)
 	}
 
+	// Check the version, this to ensure we don't read a future
+	// version that we don't understand
+	if state.Version > textStateVersion {
+		return nil, fmt.Errorf("State version %d not supported, please update.",
+			state.Version)
+	}
 	return state, nil
 }
 

terraform/state_test.go

@@ -2,7 +2,9 @@ package terraform
 
 import (
 	"bytes"
+	"encoding/json"
 	"reflect"
+	"strings"
 	"testing"
 
 	"github.com/hashicorp/terraform/config"
@@ -193,6 +195,25 @@ func TestReadWriteState(t *testing.T) {
 	}
 }
 
+func TestReadStateNewVersion(t *testing.T) {
+	type out struct {
+		Version int
+	}
+
+	buf, err := json.Marshal(&out{textStateVersion + 1})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	s, err := ReadState(bytes.NewReader(buf))
+	if s != nil {
+		t.Fatalf("unexpected: %#v", s)
+	}
+	if !strings.Contains(err.Error(), "not supported") {
+		t.Fatalf("err: %v", err)
+	}
+}
+
 func TestUpgradeV1State(t *testing.T) {
 	old := &StateV1{
 		Outputs: map[string]string{