From a433f9dd85b5e4d3f0e1e779756e08db56884764 Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Thu, 24 Sep 2020 15:22:59 +0300
Subject: [PATCH] [#42] object/transformer: Fix incorrect checksums of parent
 object

In previous implementations object size limiter left checksums of parent
object payload unset. This was caused by the closure that written calculated
checksums to the child object instead of parent one.

Construct payload checksum writers in separate function in order to prevent
closure bug.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 .../object_manager/transformer/transformer.go | 72 ++++++++++---------
 1 file changed, 38 insertions(+), 34 deletions(-)

diff --git a/pkg/services/object_manager/transformer/transformer.go b/pkg/services/object_manager/transformer/transformer.go
index 761a5a74..d7d43957 100644
--- a/pkg/services/object_manager/transformer/transformer.go
+++ b/pkg/services/object_manager/transformer/transformer.go
@@ -99,40 +99,7 @@ func (s *payloadSizeLimiter) initializeCurrent() {
 	s.target = s.targetInit()
 
 	// create payload hashers
-	s.currentHashers = []*payloadChecksumHasher{
-		{
-			hasher: sha256.New(),
-			checksumWriter: func(cs []byte) {
-				if ln := len(cs); ln != sha256.Size {
-					panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", ln, sha256.Size))
-				}
-
-				csSHA := [sha256.Size]byte{}
-				copy(csSHA[:], cs)
-
-				checksum := pkg.NewChecksum()
-				checksum.SetSHA256(csSHA)
-
-				s.current.SetPayloadChecksum(checksum)
-			},
-		},
-		{
-			hasher: tz.New(),
-			checksumWriter: func(cs []byte) {
-				if ln := len(cs); ln != tzChecksumSize {
-					panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", ln, tzChecksumSize))
-				}
-
-				csTZ := [tzChecksumSize]byte{}
-				copy(csTZ[:], cs)
-
-				checksum := pkg.NewChecksum()
-				checksum.SetTillichZemor(csTZ)
-
-				s.current.SetPayloadHomomorphicHash(checksum)
-			},
-		},
-	}
+	s.currentHashers = payloadHashersForObject(s.current)
 
 	// compose multi-writer from target and all payload hashers
 	ws := make([]io.Writer, 0, 1+len(s.currentHashers)+len(s.parentHashers))
@@ -150,6 +117,43 @@ func (s *payloadSizeLimiter) initializeCurrent() {
 	s.chunkWriter = io.MultiWriter(ws...)
 }
 
+func payloadHashersForObject(obj *object.RawObject) []*payloadChecksumHasher {
+	return []*payloadChecksumHasher{
+		{
+			hasher: sha256.New(),
+			checksumWriter: func(cs []byte) {
+				if ln := len(cs); ln != sha256.Size {
+					panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", ln, sha256.Size))
+				}
+
+				csSHA := [sha256.Size]byte{}
+				copy(csSHA[:], cs)
+
+				checksum := pkg.NewChecksum()
+				checksum.SetSHA256(csSHA)
+
+				obj.SetPayloadChecksum(checksum)
+			},
+		},
+		{
+			hasher: tz.New(),
+			checksumWriter: func(cs []byte) {
+				if ln := len(cs); ln != tzChecksumSize {
+					panic(fmt.Sprintf("wrong checksum length: expected %d, has %d", ln, tzChecksumSize))
+				}
+
+				csTZ := [tzChecksumSize]byte{}
+				copy(csTZ[:], cs)
+
+				checksum := pkg.NewChecksum()
+				checksum.SetTillichZemor(csTZ)
+
+				obj.SetPayloadHomomorphicHash(checksum)
+			},
+		},
+	}
+}
+
 func (s *payloadSizeLimiter) release(close bool) (*AccessIdentifiers, error) {
 	// Arg close is true only from Close method.
 	// We finalize parent and generate linking objects only if it is more