xl/putObject: Should take care of the situation if an object already exists at the location. (#1606)

Fixes  #1598 #1594 #1595

fs-objects.go

@@ -17,6 +17,8 @@
 package main
 
 import (
+	"crypto/md5"
+	"encoding/hex"
 	"io"
 	"path/filepath"
 	"strings"
@@ -143,7 +145,73 @@ func (fs fsObjects) GetObjectInfo(bucket, object string) (ObjectInfo, error) {
 
 // PutObject - create an object.
 func (fs fsObjects) PutObject(bucket string, object string, size int64, data io.Reader, metadata map[string]string) (string, error) {
-	return putObjectCommon(fs.storage, bucket, object, size, data, metadata)
+	// Verify if bucket is valid.
+	if !IsValidBucketName(bucket) {
+		return "", BucketNameInvalid{Bucket: bucket}
+	}
+	// Check whether the bucket exists.
+	if !isBucketExist(fs.storage, bucket) {
+		return "", BucketNotFound{Bucket: bucket}
+	}
+	if !IsValidObjectName(object) {
+		return "", ObjectNameInvalid{
+			Bucket: bucket,
+			Object: object,
+		}
+	}
+
+	fileWriter, err := fs.storage.CreateFile(bucket, object)
+	if err != nil {
+		return "", toObjectErr(err, bucket, object)
+	}
+
+	// Initialize md5 writer.
+	md5Writer := md5.New()
+
+	// Instantiate a new multi writer.
+	multiWriter := io.MultiWriter(md5Writer, fileWriter)
+
+	// Instantiate checksum hashers and create a multiwriter.
+	if size > 0 {
+		if _, err = io.CopyN(multiWriter, data, size); err != nil {
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", clErr
+			}
+			return "", toObjectErr(err, bucket, object)
+		}
+	} else {
+		if _, err = io.Copy(multiWriter, data); err != nil {
+			if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+				return "", clErr
+			}
+			return "", toObjectErr(err, bucket, object)
+		}
+	}
+
+	newMD5Hex := hex.EncodeToString(md5Writer.Sum(nil))
+	// md5Hex representation.
+	var md5Hex string
+	if len(metadata) != 0 {
+		md5Hex = metadata["md5Sum"]
+	}
+	if md5Hex != "" {
+		if newMD5Hex != md5Hex {
+			if err = safeCloseAndRemove(fileWriter); err != nil {
+				return "", err
+			}
+			return "", BadDigest{md5Hex, newMD5Hex}
+		}
+	}
+	err = fileWriter.Close()
+	if err != nil {
+		if clErr := safeCloseAndRemove(fileWriter); clErr != nil {
+			return "", clErr
+		}
+		return "", err
+	}
+
+	// Return md5sum, successfully wrote object.
+	return newMD5Hex, nil
 }
 
 func (fs fsObjects) DeleteObject(bucket, object string) error {