From 0f098d731cc3b8942c29784a02612d13b0ca9381 Mon Sep 17 00:00:00 2001
From: Matthias Fulz <mfulz@olznet.de>
Date: Sun, 3 Nov 2019 21:30:50 +0100
Subject: [PATCH] Fix: Handling of exported struct fields

---
 marshal.go          | 15 +++++++++++++--
 unmarshal.go        | 15 +++++++++++++--
 unsafe_marshal.go   | 15 +++++++++++++--
 unsafe_unmarshal.go | 15 +++++++++++++--
 4 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/marshal.go b/marshal.go
index 90f5b3c..de52cf1 100644
--- a/marshal.go
+++ b/marshal.go
@@ -244,11 +244,22 @@ func encRegister(e interface{}) (err error) {
 		}
 		encoderCache[string(t.Kind())] = f
 	case reflect.Struct:
+		zt := reflect.New(t)
+		n := zt.Elem().NumField()
+		mfields := []int{}
+		for i := 0; i < n; i++ {
+			if zt.Elem().Field(i).CanSet() {
+				mfields = append(mfields, i)
+			}
+		}
+		if len(mfields) == 0 {
+			return errors.New("ssob: No exported fields for " + string(t.Name()))
+		}
+
 		f := func(e interface{}) (ret []byte, err error) {
-			n := v.NumField()
 			bs := make([][]byte, n)
 			blen := 0
-			for i := 0; i < n; i++ {
+			for _, i := range mfields {
 				bs[i], err = marshal(v.Field(i).Interface())
 				if err != nil {
 					return nil, err
diff --git a/unmarshal.go b/unmarshal.go
index 813f987..c55b024 100644
--- a/unmarshal.go
+++ b/unmarshal.go
@@ -269,6 +269,18 @@ func decRegister(e interface{}) (err error) {
 		}
 		decoderCache[string(t.Kind())] = f
 	case reflect.Struct:
+		zt := reflect.New(t)
+		n := zt.Elem().NumField()
+		mfields := []int{}
+		for i := 0; i < n; i++ {
+			if zt.Elem().Field(i).CanSet() {
+				mfields = append(mfields, i)
+			}
+		}
+		if len(mfields) == 0 {
+			return errors.New("ssob: No exported fields for " + string(t.Name()))
+		}
+
 		f := func(e interface{}, in []byte) (n int, err error) {
 			t := reflect.TypeOf(e)
 			v := reflect.ValueOf(e)
@@ -279,8 +291,7 @@ func decRegister(e interface{}) (err error) {
 			}
 
 			vi := reflect.Indirect(v)
-			l := vi.NumField()
-			for i := 0; i < l; i++ {
+			for _, i := range mfields {
 				ni, err := unmarshal(vi.Field(i).Addr().Interface(), in[pos:])
 				pos += ni
 				if err != nil {
diff --git a/unsafe_marshal.go b/unsafe_marshal.go
index 7d3447d..a1cbfa5 100644
--- a/unsafe_marshal.go
+++ b/unsafe_marshal.go
@@ -354,11 +354,22 @@ func encRegisterUnsafe(e interface{}) (err error) {
 		}
 		unsafeEncoderCache[string(t.Kind())] = f
 	case reflect.Struct:
+		zt := reflect.New(t)
+		n := zt.Elem().NumField()
+		mfields := []int{}
+		for i := 0; i < n; i++ {
+			if zt.Elem().Field(i).CanSet() {
+				mfields = append(mfields, i)
+			}
+		}
+		if len(mfields) == 0 {
+			return errors.New("ssob: No exported fields for " + string(t.Name()))
+		}
+
 		f := func(e interface{}) (ret []byte, err error) {
-			n := v.NumField()
 			bs := make([][]byte, n)
 			blen := 0
-			for i := 0; i < n; i++ {
+			for _, i := range mfields {
 				bs[i], err = unsafeMarshal(v.Field(i).Interface())
 				if err != nil {
 					return nil, err
diff --git a/unsafe_unmarshal.go b/unsafe_unmarshal.go
index 2a8dcb0..51a7be6 100644
--- a/unsafe_unmarshal.go
+++ b/unsafe_unmarshal.go
@@ -396,6 +396,18 @@ func decRegisterUnsafe(e interface{}) (err error) {
 		}
 		unsafeDecoderCache[string(t.Kind())] = f
 	case reflect.Struct:
+		zt := reflect.New(t)
+		n := zt.Elem().NumField()
+		mfields := []int{}
+		for i := 0; i < n; i++ {
+			if zt.Elem().Field(i).CanSet() {
+				mfields = append(mfields, i)
+			}
+		}
+		if len(mfields) == 0 {
+			return errors.New("ssob: No exported fields for " + string(t.Name()))
+		}
+
 		f := func(e interface{}, in []byte) (n int, err error) {
 			t := reflect.TypeOf(e)
 			v := reflect.ValueOf(e)
@@ -406,8 +418,7 @@ func decRegisterUnsafe(e interface{}) (err error) {
 			}
 
 			vi := reflect.Indirect(v)
-			l := vi.NumField()
-			for i := 0; i < l; i++ {
+			for _, i := range mfields {
 				ni, err := unsafeUnmarshal(vi.Field(i).Addr().Interface(), in[pos:])
 				pos += ni
 				if err != nil {