Wrap hash state not marshallable errors with ErrUnsupported (#287)

* fix:wrap current non marshallable errors with ErrUnsupported

* fix:move hash to struct with wrapper

* fix:use errors.Is for assertion

Author: mertakman

hash.go

@@ -372,11 +372,19 @@ func (h *evpHash) Clone() (HashCloner, error) {
 	return h2, nil
 }
 
-var errHashNotMarshallable = errors.New("openssl: hash state is not marshallable")
+type errMarshallUnsupported struct{}
+
+func (e errMarshallUnsupported) Error() string {
+	return "cryptokit: hash state is not marshallable"
+}
+
+func (e errMarshallUnsupported) Unwrap() error {
+	return errors.ErrUnsupported
+}
 
 func (d *evpHash) MarshalBinary() ([]byte, error) {
 	if !d.alg.marshallable {
-		return nil, errHashNotMarshallable
+		return nil, errMarshallUnsupported{}
 	}
 	buf := make([]byte, 0, d.alg.marshalledSize)
 	return d.AppendBinary(buf)
@@ -385,7 +393,7 @@ func (d *evpHash) MarshalBinary() ([]byte, error) {
 func (d *evpHash) AppendBinary(buf []byte) ([]byte, error) {
 	defer runtime.KeepAlive(d)
 	if !d.alg.marshallable {
-		return nil, errHashNotMarshallable
+		return nil, errMarshallUnsupported{}
 	}
 	d.init()
 	switch d.alg.provider {
@@ -402,7 +410,7 @@ func (d *evpHash) UnmarshalBinary(b []byte) error {
 	defer runtime.KeepAlive(d)
 	d.init()
 	if !d.alg.marshallable {
-		return errHashNotMarshallable
+		return errMarshallUnsupported{}
 	}
 	if len(b) < len(d.alg.magic) || string(b[:len(d.alg.magic)]) != d.alg.magic {
 		return errors.New("openssl: invalid hash state identifier")

hash_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto"
 	"encoding"
+	"errors"
 	"hash"
 	"io"
 	"runtime"
@@ -195,7 +196,7 @@ func TestHash_BinaryAppender(t *testing.T) {
 			// Append binary data to the prebuilt slice
 			state, err := hashWithBinaryAppender.AppendBinary(prebuiltSlice)
 			if err != nil {
-				if strings.Contains(err.Error(), "hash state is not marshallable") {
+				if errors.Is(err, errors.ErrUnsupported) {
 					t.Skip("AppendBinary not supported")
 				}
 				t.Errorf("could not append binary: %v", err)