Adding object donut type

pkg/storage/donut/object/objectv1/objectv1.go

@@ -0,0 +1,65 @@
+package objectv1
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/gob"
+	"errors"
+	"io"
+	"strconv"
+	"time"
+)
+
+// Package Version
+const Version = uint32(1)
+
+// ObjectType is the type of object stored. It is either an Object or Multipart Object.
+type ObjectType uint8
+
+const (
+	// Object is a full object
+	Object ObjectType = iota
+	// MultipartObject is a collection of Objects uploaded separately that represent a large object.
+	MultipartObject
+)
+
+// Object Metadata
+type ObjectMetadata struct {
+	Bucket      string
+	Key         string
+	ErasurePart uint16
+	EncodedPart uint8
+
+	ContentType string
+	Created     time.Time
+	Length      uint64
+	Md5         []byte
+	ObjectType  ObjectType
+}
+
+func Write(target io.Writer, metadata ObjectMetadata, reader io.Reader) error {
+	buffer := new(bytes.Buffer)
+	binary.Write(buffer, binary.LittleEndian, uint32(Version))
+	encoder := gob.NewEncoder(buffer)
+	if err := encoder.Encode(metadata); err != nil {
+		return err
+	}
+	reader = io.MultiReader(buffer, reader)
+	_, err := io.Copy(target, reader)
+	return err
+}
+
+func ReadMetadata(reader io.Reader) (metadata ObjectMetadata, err error) {
+	versionBytes := make([]byte, 4)
+	if err := binary.Read(reader, binary.LittleEndian, versionBytes); err != nil {
+		return metadata, err
+	}
+	var version uint32
+	version = binary.LittleEndian.Uint32(versionBytes)
+	if version != 1 {
+		return metadata, errors.New("Unknown Version: " + strconv.FormatUint(uint64(version), 10))
+	}
+	decoder := gob.NewDecoder(reader)
+	err = decoder.Decode(&metadata)
+	return metadata, err
+}