factory: use customised deep compare

reflect.DeepEqual would return false when comparing nil map/slice with
empty map/slice. We would want to return success in such case, since it
is possible for upper layers to send these kind of configs.

Fixes: #844

Signed-off-by: Peng Tao <bergwolf@gmail.com>

virtcontainers/factory/factory.go

@@ -100,6 +100,71 @@ func resetHypervisorConfig(config *vc.VMConfig) {
 	config.ProxyConfig = vc.ProxyConfig{}
 }
 
+func compareStruct(foo, bar reflect.Value) bool {
+	for i := 0; i < foo.NumField(); i++ {
+		if !deepCompareValue(foo.Field(i), bar.Field(i)) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func compareMap(foo, bar reflect.Value) bool {
+	if foo.Len() != bar.Len() {
+		return false
+	}
+
+	for _, k := range foo.MapKeys() {
+		if !deepCompareValue(foo.MapIndex(k), bar.MapIndex(k)) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func compareSlice(foo, bar reflect.Value) bool {
+	if foo.Len() != bar.Len() {
+		return false
+	}
+	for j := 0; j < foo.Len(); j++ {
+		if !deepCompareValue(foo.Index(j), bar.Index(j)) {
+			return false
+		}
+	}
+	return true
+}
+
+func deepCompareValue(foo, bar reflect.Value) bool {
+	if !foo.IsValid() || !bar.IsValid() {
+		return foo.IsValid() == bar.IsValid()
+	}
+
+	if foo.Type() != bar.Type() {
+		return false
+	}
+	switch foo.Kind() {
+	case reflect.Map:
+		return compareMap(foo, bar)
+	case reflect.Array:
+		fallthrough
+	case reflect.Slice:
+		return compareSlice(foo, bar)
+	case reflect.Struct:
+		return compareStruct(foo, bar)
+	default:
+		return foo.Interface() == bar.Interface()
+	}
+}
+
+func deepCompare(foo, bar interface{}) bool {
+	v1 := reflect.ValueOf(foo)
+	v2 := reflect.ValueOf(bar)
+
+	return deepCompareValue(v1, v2)
+}
+
 // It's important that baseConfig and newConfig are passed by value!
 func checkVMConfig(config1, config2 vc.VMConfig) error {
 	if config1.HypervisorType != config2.HypervisorType {
@@ -114,7 +179,7 @@ func checkVMConfig(config1, config2 vc.VMConfig) error {
 	resetHypervisorConfig(&config1)
 	resetHypervisorConfig(&config2)
 
-	if !reflect.DeepEqual(config1, config2) {
+	if !deepCompare(config1, config2) {
 		return fmt.Errorf("hypervisor config does not match, base: %+v. new: %+v", config1, config2)
 	}
 

virtcontainers/factory/factory_test.go

@@ -14,6 +14,7 @@ import (
 	"github.com/stretchr/testify/assert"
 
 	vc "github.com/kata-containers/runtime/virtcontainers"
+	"github.com/kata-containers/runtime/virtcontainers/factory/base"
 )
 
 func TestNewFactory(t *testing.T) {
@@ -248,3 +249,66 @@ func TestFactoryGetVM(t *testing.T) {
 
 	f.CloseFactory(ctx)
 }
+
+func TestDeepCompare(t *testing.T) {
+	assert := assert.New(t)
+
+	foo := vc.VMConfig{}
+	bar := vc.VMConfig{}
+	assert.True(deepCompare(foo, bar))
+
+	foo.HypervisorConfig.NumVCPUs = 1
+	assert.False(deepCompare(foo, bar))
+	bar.HypervisorConfig.NumVCPUs = 1
+	assert.True(deepCompare(foo, bar))
+
+	// slice
+	foo.HypervisorConfig.KernelParams = []vc.Param{}
+	assert.True(deepCompare(foo, bar))
+	foo.HypervisorConfig.KernelParams = append(foo.HypervisorConfig.KernelParams, vc.Param{Key: "key", Value: "value"})
+	assert.False(deepCompare(foo, bar))
+	bar.HypervisorConfig.KernelParams = append(bar.HypervisorConfig.KernelParams, vc.Param{Key: "key", Value: "value"})
+	assert.True(deepCompare(foo, bar))
+
+	// map
+	var fooMap map[string]vc.VMConfig
+	var barMap map[string]vc.VMConfig
+	assert.False(deepCompare(foo, fooMap))
+	assert.True(deepCompare(fooMap, barMap))
+	fooMap = make(map[string]vc.VMConfig)
+	assert.True(deepCompare(fooMap, barMap))
+	fooMap["foo"] = foo
+	assert.False(deepCompare(fooMap, barMap))
+	barMap = make(map[string]vc.VMConfig)
+	assert.False(deepCompare(fooMap, barMap))
+	barMap["foo"] = bar
+	assert.True(deepCompare(fooMap, barMap))
+
+	// invalid interface
+	var f1 vc.Factory
+	var f2 vc.Factory
+	var f3 base.FactoryBase
+	assert.True(deepCompare(f1, f2))
+	assert.True(deepCompare(f1, f3))
+
+	// valid interface
+	var config Config
+	var err error
+	ctx := context.Background()
+	config.VMConfig = vc.VMConfig{
+		HypervisorType: vc.MockHypervisor,
+		AgentType:      vc.NoopAgentType,
+		ProxyType:      vc.NoopProxyType,
+	}
+	testDir, _ := ioutil.TempDir("", "vmfactory-tmp-")
+	config.VMConfig.HypervisorConfig = vc.HypervisorConfig{
+		KernelPath: testDir,
+		ImagePath:  testDir,
+	}
+	f1, err = NewFactory(ctx, config, false)
+	assert.Nil(err)
+	assert.True(deepCompare(f1, f1))
+	f2, err = NewFactory(ctx, config, false)
+	assert.Nil(err)
+	assert.False(deepCompare(f1, f2))
+}