history: set Tags

Correctly set the tags of history layers.  Also make sure to nil the
loop `layer` variable when it has no parent.

Fixes: containers/podman/issues/17763
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

libimage/history.go

@@ -51,7 +51,6 @@ func (i *Image) History(ctx context.Context) ([]ImageHistory, error) {
 		}
 
 		if layer != nil {
-			history.Tags = layer.Names
 			if !ociImage.History[x].EmptyLayer {
 				history.Size = layer.UncompressedSize
 			}
@@ -64,8 +63,13 @@ func (i *Image) History(ctx context.Context) ([]ImageHistory, error) {
 					history.ID = id
 					usedIDs[id] = true
 				}
+				for i := range node.images {
+					history.Tags = append(history.Tags, node.images[i].Names()...)
+				}
 			}
-			if layer.Parent != "" && !ociImage.History[x].EmptyLayer {
+			if layer.Parent == "" {
+				layer = nil
+			} else if !ociImage.History[x].EmptyLayer {
 				layer, err = i.runtime.store.Layer(layer.Parent)
 				if err != nil {
 					return nil, err

libimage/history_test.go

@@ -0,0 +1,28 @@
+package libimage
+
+import (
+	"context"
+	"testing"
+
+	"github.com/containers/common/pkg/config"
+	"github.com/stretchr/testify/require"
+)
+
+func TestHistory(t *testing.T) {
+	runtime, cleanup := testNewRuntime(t)
+	defer cleanup()
+	ctx := context.Background()
+
+	name := "quay.io/libpod/alpine:3.10.2"
+	pullOptions := &PullOptions{}
+	pulledImages, err := runtime.Pull(ctx, name, config.PullPolicyAlways, pullOptions)
+	require.NoError(t, err)
+	require.Len(t, pulledImages, 1)
+
+	history, err := pulledImages[0].History(ctx)
+	require.NoError(t, err)
+	require.Len(t, history, 2)
+
+	require.Equal(t, []string{name}, history[0].Tags)
+	require.Len(t, history[1].Tags, 0)
+}