Merge pull request #17 from m-mizutani/enhance/prevent-circular

Prevent circular reference

clone.go

@@ -1,11 +1,28 @@
 package masq
 
 import (
+	"context"
 	"reflect"
 	"unsafe"
 )
 
-func (x *masq) clone(fieldName string, src reflect.Value, tag string) reflect.Value {
+type ctxKeyDepth struct{}
+
+const (
+	maxDepth = 32
+)
+
+func (x *masq) clone(ctx context.Context, fieldName string, src reflect.Value, tag string) reflect.Value {
+	if v, ok := ctx.Value(ctxKeyDepth{}).(int); !ok {
+		ctx = context.WithValue(ctx, ctxKeyDepth{}, 0)
+	} else {
+		if v >= maxDepth {
+			return src
+		}
+		ctx = context.WithValue(ctx, ctxKeyDepth{}, v+1)
+
+	}
+
 	if _, ok := x.allowedTypes[src.Type()]; ok {
 		return src
 	}
@@ -68,7 +85,7 @@ func (x *masq) clone(fieldName string, src reflect.Value, tag string) reflect.Va
 			}
 
 			tagValue := f.Tag.Get("masq")
-			copied := x.clone(f.Name, srcValue, tagValue)
+			copied := x.clone(ctx, f.Name, srcValue, tagValue)
 			dstValue.Set(copied)
 		}
 		return dst.Elem()
@@ -78,14 +95,14 @@ func (x *masq) clone(fieldName string, src reflect.Value, tag string) reflect.Va
 		keys := src.MapKeys()
 		for i := 0; i < src.Len(); i++ {
 			mValue := src.MapIndex(keys[i])
-			dst.SetMapIndex(keys[i], x.clone(keys[i].String(), mValue, ""))
+			dst.SetMapIndex(keys[i], x.clone(ctx, keys[i].String(), mValue, ""))
 		}
 		return dst
 
 	case reflect.Slice:
 		dst := reflect.MakeSlice(src.Type(), src.Len(), src.Cap())
 		for i := 0; i < src.Len(); i++ {
-			dst.Index(i).Set(x.clone(fieldName, src.Index(i), ""))
+			dst.Index(i).Set(x.clone(ctx, fieldName, src.Index(i), ""))
 		}
 		return dst
 
@@ -96,21 +113,21 @@ func (x *masq) clone(fieldName string, src reflect.Value, tag string) reflect.Va
 
 		dst := reflect.New(src.Type()).Elem()
 		for i := 0; i < src.Len(); i++ {
-			dst.Index(i).Set(x.clone(fieldName, src.Index(i), ""))
+			dst.Index(i).Set(x.clone(ctx, fieldName, src.Index(i), ""))
 		}
 		return dst
 
 	case reflect.Ptr:
 		dst := reflect.New(src.Elem().Type())
-		copied := x.clone(fieldName, src.Elem(), tag)
+		copied := x.clone(ctx, fieldName, src.Elem(), tag)
 		dst.Elem().Set(copied)
 		return dst
 
 	case reflect.Interface:
 		if src.IsNil() {
 			return src
 		}
-		return x.clone(fieldName, src.Elem(), tag)
+		return x.clone(ctx, fieldName, src.Elem(), tag)
 
 	default:
 		dst := reflect.New(src.Type())

clone_test.go

@@ -328,3 +328,18 @@ func TestNilInterface(t *testing.T) {
 	logger.Info("hello", slog.Any("test", myStruct{}))
 	gt.S(t, buf.String()).Contains("null")
 }
+
+func TestCircularReference(t *testing.T) {
+	type myStruct struct {
+		Child *myStruct
+		Str   string
+	}
+	data := &myStruct{
+		Str: "blue",
+	}
+	data.Child = data
+
+	c := masq.NewMasq(masq.WithContain("blue"))
+	newData := c.Redact(data).(*myStruct)
+	gt.V(t, newData.Child.Child.Str).Equal("[REDACTED]")
+}

go.mod

@@ -4,4 +4,4 @@ go 1.22
 
 require github.com/m-mizutani/gt v0.0.7
 
-require github.com/google/go-cmp v0.5.9 // indirect
+require github.com/google/go-cmp v0.6.0 // indirect

go.sum

@@ -1,4 +1,4 @@
-github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
-github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/m-mizutani/gt v0.0.7 h1:wKESp5LWdKpKMySX4Rf05iXYUGtoQ3aI7xOO9VVHAoY=
 github.com/m-mizutani/gt v0.0.7/go.mod h1:0MPYSfGBLmYjTduzADVmIqD58ELQ5IfBFiK/f0FmB3k=

masq.go

@@ -1,6 +1,7 @@
 package masq
 
 import (
+	"context"
 	"reflect"
 
 	"log/slog"
@@ -49,7 +50,9 @@ func (x *masq) redact(k string, v any) any {
 	if v == nil {
 		return nil
 	}
-	copied := x.clone(k, reflect.ValueOf(v), "")
+
+	ctx := context.Background()
+	copied := x.clone(ctx, k, reflect.ValueOf(v), "")
 	return copied.Interface()
 }