[#1103] node: Implement Get\Head requests for EC object

Signed-off-by: Anton Nikiforov <an.nikiforov@yadro.com>

pkg/local_object_storage/metabase/util.go

@@ -119,6 +119,11 @@ const (
 	//	Key: container ID + type
 	//  Value: container size in bytes as little-endian uint64
 	containerCountersPrefix
+
+	// ecInfoPrefix is used for storing relation between EC parent id and chunk id.
+	//	Key: container ID + type
+	//  Value: Object id
+	ecInfoPrefix
 )
 
 const (
@@ -190,6 +195,11 @@ func splitBucketName(cnr cid.ID, key []byte) []byte {
 	return bucketName(cnr, splitPrefix, key)
 }
 
+// ecInfoBucketName returns <CID>_ecinfo.
+func ecInfoBucketName(cnr cid.ID, key []byte) []byte {
+	return bucketName(cnr, ecInfoPrefix, key)
+}
+
 // addressKey returns key for K-V tables when key is a whole address.
 func addressKey(addr oid.Address, key []byte) []byte {
 	addr.Container().Encode(key)