hash: implement the encoding.BinaryAppender interface

For #62384

Change-Id: Ia6de028741e43449bcf54ba73ec9b0cad4d4e88a
GitHub-Last-Rev: 192f389d463d372a338dca82827a871888a53bb0
GitHub-Pull-Request: golang/go#68738
Reviewed-on: https://go-review.googlesource.com/c/go/+/603255
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: David Chase <drchase@google.com>

8 files changed, 118 insertions, 18 deletions

diff --git a/src/hash/adler32/adler32.go b/src/hash/adler32/adler32.go
index ed9ccad910..88b4ccf2fe 100644
--- a/src/hash/adler32/adler32.go
+++ b/src/hash/adler32/adler32.go
@@ -57,13 +57,16 @@ const (
 	marshaledSize = len(magic) + 4
 )
 
-func (d *digest) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize)
+func (d *digest) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic...)
 	b = byteorder.BeAppendUint32(b, uint32(*d))
 	return b, nil
 }
 
+func (d *digest) MarshalBinary() ([]byte, error) {
+	return d.AppendBinary(make([]byte, 0, marshaledSize))
+}
+
 func (d *digest) UnmarshalBinary(b []byte) error {
 	if len(b) < len(magic) || string(b[:len(magic)]) != magic {
 		return errors.New("hash/adler32: invalid hash state identifier")
diff --git a/src/hash/adler32/adler32_test.go b/src/hash/adler32/adler32_test.go
index 6bac802507..ebb9a438a6 100644
--- a/src/hash/adler32/adler32_test.go
+++ b/src/hash/adler32/adler32_test.go
@@ -103,11 +103,23 @@ func TestGoldenMarshal(t *testing.T) {
 			continue
 		}
 
+		stateAppend, err := h.(encoding.BinaryAppender).AppendBinary(make([]byte, 4, 32))
+		if err != nil {
+			t.Errorf("could not marshal: %v", err)
+			continue
+		}
+		stateAppend = stateAppend[4:]
+
 		if string(state) != g.halfState {
 			t.Errorf("checksum(%q) state = %q, want %q", g.in, state, g.halfState)
 			continue
 		}
 
+		if string(stateAppend) != g.halfState {
+			t.Errorf("checksum(%q) state = %q, want %q", g.in, stateAppend, g.halfState)
+			continue
+		}
+
 		if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
 			t.Errorf("could not unmarshal: %v", err)
 			continue
diff --git a/src/hash/crc32/crc32.go b/src/hash/crc32/crc32.go
index 3964646b27..b659959959 100644
--- a/src/hash/crc32/crc32.go
+++ b/src/hash/crc32/crc32.go
@@ -170,14 +170,18 @@ const (
 	marshaledSize = len(magic) + 4 + 4
 )
 
-func (d *digest) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize)
+func (d *digest) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic...)
 	b = byteorder.BeAppendUint32(b, tableSum(d.tab))
 	b = byteorder.BeAppendUint32(b, d.crc)
 	return b, nil
 }
 
+func (d *digest) MarshalBinary() ([]byte, error) {
+	return d.AppendBinary(make([]byte, 0, marshaledSize))
+
+}
+
 func (d *digest) UnmarshalBinary(b []byte) error {
 	if len(b) < len(magic) || string(b[:len(magic)]) != magic {
 		return errors.New("hash/crc32: invalid hash state identifier")
diff --git a/src/hash/crc32/crc32_test.go b/src/hash/crc32/crc32_test.go
index 5a3e134cf7..10c28f9533 100644
--- a/src/hash/crc32/crc32_test.go
+++ b/src/hash/crc32/crc32_test.go
@@ -133,11 +133,23 @@ func TestGoldenMarshal(t *testing.T) {
 				continue
 			}
 
+			stateAppend, err := h.(encoding.BinaryAppender).AppendBinary(make([]byte, 4, 32))
+			if err != nil {
+				t.Errorf("could not marshal: %v", err)
+				continue
+			}
+			stateAppend = stateAppend[4:]
+
 			if string(state) != g.halfStateIEEE {
 				t.Errorf("IEEE(%q) state = %q, want %q", g.in, state, g.halfStateIEEE)
 				continue
 			}
 
+			if string(stateAppend) != g.halfStateIEEE {
+				t.Errorf("IEEE(%q) state = %q, want %q", g.in, stateAppend, g.halfStateIEEE)
+				continue
+			}
+
 			if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
 				t.Errorf("could not unmarshal: %v", err)
 				continue
@@ -165,11 +177,23 @@ func TestGoldenMarshal(t *testing.T) {
 				continue
 			}
 
+			stateAppend, err := h.(encoding.BinaryAppender).AppendBinary(make([]byte, 4, 32))
+			if err != nil {
+				t.Errorf("could not marshal: %v", err)
+				continue
+			}
+			stateAppend = stateAppend[4:]
+
 			if string(state) != g.halfStateCastagnoli {
 				t.Errorf("Castagnoli(%q) state = %q, want %q", g.in, state, g.halfStateCastagnoli)
 				continue
 			}
 
+			if string(stateAppend) != g.halfStateCastagnoli {
+				t.Errorf("Castagnoli(%q) state = %q, want %q", g.in, stateAppend, g.halfStateCastagnoli)
+				continue
+			}
+
 			if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
 				t.Errorf("could not unmarshal: %v", err)
 				continue
diff --git a/src/hash/crc64/crc64.go b/src/hash/crc64/crc64.go
index 4cdb4c7e77..bdfd82ed31 100644
--- a/src/hash/crc64/crc64.go
+++ b/src/hash/crc64/crc64.go
@@ -111,14 +111,17 @@ const (
 	marshaledSize = len(magic) + 8 + 8
 )
 
-func (d *digest) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize)
+func (d *digest) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic...)
 	b = byteorder.BeAppendUint64(b, tableSum(d.tab))
 	b = byteorder.BeAppendUint64(b, d.crc)
 	return b, nil
 }
 
+func (d *digest) MarshalBinary() ([]byte, error) {
+	return d.AppendBinary(make([]byte, 0, marshaledSize))
+}
+
 func (d *digest) UnmarshalBinary(b []byte) error {
 	if len(b) < len(magic) || string(b[:len(magic)]) != magic {
 		return errors.New("hash/crc64: invalid hash state identifier")
diff --git a/src/hash/crc64/crc64_test.go b/src/hash/crc64/crc64_test.go
index 9cf602c82f..06c428c81f 100644
--- a/src/hash/crc64/crc64_test.go
+++ b/src/hash/crc64/crc64_test.go
@@ -88,11 +88,23 @@ func TestGoldenMarshal(t *testing.T) {
 				continue
 			}
 
+			stateAppend, err := h.(encoding.BinaryAppender).AppendBinary(make([]byte, 4, 32))
+			if err != nil {
+				t.Errorf("could not marshal: %v", err)
+				continue
+			}
+			stateAppend = stateAppend[4:]
+
 			if string(state) != g.halfStateISO {
 				t.Errorf("ISO crc64(%q) state = %q, want %q", g.in, state, g.halfStateISO)
 				continue
 			}
 
+			if string(stateAppend) != g.halfStateISO {
+				t.Errorf("ISO crc64(%q) state = %q, want %q", g.in, stateAppend, g.halfStateISO)
+				continue
+			}
+
 			if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
 				t.Errorf("could not unmarshal: %v", err)
 				continue
@@ -120,11 +132,23 @@ func TestGoldenMarshal(t *testing.T) {
 				continue
 			}
 
+			stateAppend, err := h.(encoding.BinaryAppender).AppendBinary(make([]byte, 4, 32))
+			if err != nil {
+				t.Errorf("could not marshal: %v", err)
+				continue
+			}
+			stateAppend = stateAppend[4:]
+
 			if string(state) != g.halfStateECMA {
 				t.Errorf("ECMA crc64(%q) state = %q, want %q", g.in, state, g.halfStateECMA)
 				continue
 			}
 
+			if string(stateAppend) != g.halfStateECMA {
+				t.Errorf("ECMA crc64(%q) state = %q, want %q", g.in, stateAppend, g.halfStateECMA)
+				continue
+			}
+
 			if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
 				t.Errorf("could not unmarshal: %v", err)
 				continue
diff --git a/src/hash/fnv/fnv.go b/src/hash/fnv/fnv.go
index bf95bb32a3..e7463795cd 100644
--- a/src/hash/fnv/fnv.go
+++ b/src/hash/fnv/fnv.go
@@ -219,50 +219,68 @@ const (
 	marshaledSize128 = len(magic128) + 8*2
 )
 
-func (s *sum32) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize32)
+func (s *sum32) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic32...)
 	b = byteorder.BeAppendUint32(b, uint32(*s))
 	return b, nil
 }
 
-func (s *sum32a) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize32)
+func (s *sum32) MarshalBinary() ([]byte, error) {
+	return s.AppendBinary(make([]byte, 0, marshaledSize32))
+}
+
+func (s *sum32a) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic32a...)
 	b = byteorder.BeAppendUint32(b, uint32(*s))
 	return b, nil
 }
 
-func (s *sum64) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize64)
+func (s *sum32a) MarshalBinary() ([]byte, error) {
+	return s.AppendBinary(make([]byte, 0, marshaledSize32))
+}
+
+func (s *sum64) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic64...)
 	b = byteorder.BeAppendUint64(b, uint64(*s))
 	return b, nil
 }
 
-func (s *sum64a) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize64)
+func (s *sum64) MarshalBinary() ([]byte, error) {
+	return s.AppendBinary(make([]byte, 0, marshaledSize64))
+}
+
+func (s *sum64a) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic64a...)
 	b = byteorder.BeAppendUint64(b, uint64(*s))
 	return b, nil
 }
 
-func (s *sum128) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize128)
+func (s *sum64a) MarshalBinary() ([]byte, error) {
+	return s.AppendBinary(make([]byte, 0, marshaledSize64))
+}
+
+func (s *sum128) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic128...)
 	b = byteorder.BeAppendUint64(b, s[0])
 	b = byteorder.BeAppendUint64(b, s[1])
 	return b, nil
 }
 
-func (s *sum128a) MarshalBinary() ([]byte, error) {
-	b := make([]byte, 0, marshaledSize128)
+func (s *sum128) MarshalBinary() ([]byte, error) {
+	return s.AppendBinary(make([]byte, 0, marshaledSize128))
+}
+
+func (s *sum128a) AppendBinary(b []byte) ([]byte, error) {
 	b = append(b, magic128a...)
 	b = byteorder.BeAppendUint64(b, s[0])
 	b = byteorder.BeAppendUint64(b, s[1])
 	return b, nil
 }
 
+func (s *sum128a) MarshalBinary() ([]byte, error) {
+	return s.AppendBinary(make([]byte, 0, marshaledSize128))
+}
+
 func (s *sum32) UnmarshalBinary(b []byte) error {
 	if len(b) < len(magic32) || string(b[:len(magic32)]) != magic32 {
 		return errors.New("hash/fnv: invalid hash state identifier")
diff --git a/src/hash/fnv/fnv_test.go b/src/hash/fnv/fnv_test.go
index 7b1f7a32ea..4219460e46 100644
--- a/src/hash/fnv/fnv_test.go
+++ b/src/hash/fnv/fnv_test.go
@@ -128,11 +128,23 @@ func TestGoldenMarshal(t *testing.T) {
 					continue
 				}
 
+				stateAppend, err := h.(encoding.BinaryAppender).AppendBinary(make([]byte, 4, 32))
+				if err != nil {
+					t.Errorf("could not marshal: %v", err)
+					continue
+				}
+				stateAppend = stateAppend[4:]
+
 				if string(state) != g.halfState {
 					t.Errorf("checksum(%q) state = %q, want %q", g.in, state, g.halfState)
 					continue
 				}
 
+				if string(stateAppend) != g.halfState {
+					t.Errorf("checksum(%q) state = %q, want %q", g.in, stateAppend, g.halfState)
+					continue
+				}
+
 				if err := h2.(encoding.BinaryUnmarshaler).UnmarshalBinary(state); err != nil {
 					t.Errorf("could not unmarshal: %v", err)
 					continue