Fix nil checking on typed interface

- Partially resoles go-gitea#17596
- Resolves SA4023 errors.
- Ensure correctly that typed interface are nil.

modules/indexer/code/indexer.go

@@ -18,6 +18,7 @@ import (
 	"code.gitea.io/gitea/modules/queue"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
+	giteautil "code.gitea.io/gitea/modules/util"
 )
 
 // SearchResult result of performing a search in a repo
@@ -185,7 +186,7 @@ func Init() {
 
 			rIndexer, populate, err = NewBleveIndexer(setting.Indexer.RepoPath)
 			if err != nil {
-				if rIndexer != nil {
+				if !giteautil.IsInterfaceNil(rIndexer) {
 					rIndexer.Close()
 				}
 				cancel()
@@ -205,7 +206,7 @@ func Init() {
 
 			rIndexer, populate, err = NewElasticSearchIndexer(setting.Indexer.RepoConnStr, setting.Indexer.RepoIndexerName)
 			if err != nil {
-				if rIndexer != nil {
+				if !giteautil.IsInterfaceNil(rIndexer) {
 					rIndexer.Close()
 				}
 				cancel()

modules/util/util.go

@@ -9,6 +9,7 @@ import (
 	"crypto/rand"
 	"errors"
 	"math/big"
+	"reflect"
 	"strconv"
 	"strings"
 )
@@ -161,3 +162,14 @@ func RandomString(length int64) (string, error) {
 	}
 	return string(bytes), nil
 }
+
+// IsInterfaceNil checks if a variable with a typed interface is nil.
+// Because interface{} == nil is always false.
+func IsInterfaceNil(i interface{}) bool {
+	switch reflect.TypeOf(i).Kind() {
+	case reflect.Ptr, reflect.Map, reflect.Array, reflect.Chan, reflect.Slice:
+		return reflect.ValueOf(i).IsNil()
+	default:
+		return false
+	}
+}

modules/util/util_test.go

@@ -169,3 +169,30 @@ func Test_OptionalBool(t *testing.T) {
 	assert.Equal(t, OptionalBoolTrue, OptionalBoolParse("t"))
 	assert.Equal(t, OptionalBoolTrue, OptionalBoolParse("True"))
 }
+
+type SampleInterface interface {
+	Hello()
+}
+
+type BasicInterface int
+
+func (BasicInterface) Hello() {
+}
+
+func returnFilledBasicInterface() BasicInterface {
+	return BasicInterface(123123)
+}
+
+func returnNil() *BasicInterface {
+	return nil
+}
+
+func TestTypedInterfaceNil(t *testing.T) {
+	var info SampleInterface
+
+	info = returnNil()
+	assert.Equal(t, IsInterfaceNil(info), true)
+
+	info = returnFilledBasicInterface()
+	assert.Equal(t, IsInterfaceNil(info), false)
+}

routers/web/base.go

@@ -20,6 +20,7 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/storage"
 	"code.gitea.io/gitea/modules/templates"
+	giteautil "code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web/middleware"
 	"code.gitea.io/gitea/services/auth"
 
@@ -130,7 +131,7 @@ func Recovery() func(next http.Handler) http.Handler {
 					log.Error("%v", combinedErr)
 
 					sessionStore := session.GetSession(req)
-					if sessionStore == nil {
+					if giteautil.IsInterfaceNil(sessionStore) {
 						if setting.IsProd {
 							http.Error(w, http.StatusText(500), 500)
 						} else {