Merge pull request #663 from harshavardhana/pr_out_add_missing_strongly_typed_errors_for_donut

pkg/storage/donut/donut.go

@@ -16,11 +16,7 @@
 
 package donut
 
-import (
-	"errors"
-
-	"github.com/minio/minio/pkg/iodine"
-)
+import "github.com/minio/minio/pkg/iodine"
 
 // donut struct internal data
 type donut struct {
@@ -73,7 +69,7 @@ func (d donut) attachDonutNode(hostname string, disks []string) error {
 // NewDonut - instantiate a new donut
 func NewDonut(donutName string, nodeDiskMap map[string][]string) (Donut, error) {
 	if donutName == "" || len(nodeDiskMap) == 0 {
-		return nil, iodine.New(errors.New("invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	nodes := make(map[string]Node)
 	buckets := make(map[string]Bucket)
@@ -84,7 +80,7 @@ func NewDonut(donutName string, nodeDiskMap map[string][]string) (Donut, error)
 	}
 	for k, v := range nodeDiskMap {
 		if len(v) == 0 {
-			return nil, iodine.New(errors.New("invalid number of disks per node"), nil)
+			return nil, iodine.New(InvalidDisksArgument{}, nil)
 		}
 		err := d.attachDonutNode(k, v)
 		if err != nil {

pkg/storage/donut/donut_bucket.go

@@ -17,7 +17,6 @@
 package donut
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -50,7 +49,7 @@ func NewBucket(bucketName, aclType, donutName string, nodes map[string]Node) (Bu
 		"aclType":    aclType,
 	}
 	if strings.TrimSpace(bucketName) == "" || strings.TrimSpace(donutName) == "" {
-		return nil, nil, iodine.New(errors.New("invalid argument"), errParams)
+		return nil, nil, iodine.New(InvalidArgument{}, errParams)
 	}
 	bucketMetadata := make(map[string]string)
 	bucketMetadata["acl"] = aclType
@@ -92,7 +91,7 @@ func (b bucket) ListObjects() (map[string]Object, error) {
 				}
 				objectName, ok := newObjectMetadata["object"]
 				if !ok {
-					return nil, iodine.New(errors.New("object corrupted"), nil)
+					return nil, iodine.New(ObjectCorrupted{Object: object.Name()}, nil)
 				}
 				b.objects[objectName] = newObject
 			}
@@ -121,7 +120,7 @@ func (b bucket) GetObject(objectName string) (reader io.ReadCloser, size int64,
 		return nil, 0, iodine.New(err, nil)
 	}
 	if objectName == "" || writer == nil || len(objectMetadata) == 0 {
-		return nil, 0, iodine.New(errors.New("invalid argument"), nil)
+		return nil, 0, iodine.New(InvalidArgument{}, nil)
 	}
 	size, err = strconv.ParseInt(objectMetadata["size"], 10, 64)
 	if err != nil {
@@ -140,7 +139,7 @@ func (b bucket) GetObject(objectName string) (reader io.ReadCloser, size int64,
 // PutObject - put a new object
 func (b bucket) PutObject(objectName string, objectData io.Reader, expectedMD5Sum string, metadata map[string]string) (string, error) {
 	if objectName == "" || objectData == nil {
-		return "", iodine.New(errors.New("invalid argument"), nil)
+		return "", iodine.New(InvalidArgument{}, nil)
 	}
 	writers, err := b.getDiskWriters(b.normalizeObjectName(objectName), "data")
 	if err != nil {

pkg/storage/donut/donut_bucket_internal.go

@@ -21,7 +21,6 @@ import (
 	"crypto/md5"
 	"encoding/hex"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"hash"
 	"io"
@@ -47,17 +46,17 @@ func (b bucket) isMD5SumEqual(expectedMD5Sum, actualMD5Sum string) error {
 			return iodine.New(err, nil)
 		}
 		if !bytes.Equal(expectedMD5SumBytes, actualMD5SumBytes) {
-			return iodine.New(errors.New("bad digest, md5sum mismatch"), nil)
+			return iodine.New(BadDigest{}, nil)
 		}
 		return nil
 	}
-	return iodine.New(errors.New("invalid argument"), nil)
+	return iodine.New(InvalidArgument{}, nil)
 }
 
 // writeObjectMetadata - write additional object metadata
 func (b bucket) writeObjectMetadata(objectName string, objectMetadata map[string]string) error {
 	if len(objectMetadata) == 0 {
-		return iodine.New(errors.New("invalid argument"), nil)
+		return iodine.New(InvalidArgument{}, nil)
 	}
 	objectMetadataWriters, err := b.getDiskWriters(objectName, objectMetadataConfig)
 	if err != nil {
@@ -78,7 +77,7 @@ func (b bucket) writeObjectMetadata(objectName string, objectMetadata map[string
 // writeDonutObjectMetadata - write donut related object metadata
 func (b bucket) writeDonutObjectMetadata(objectName string, objectMetadata map[string]string) error {
 	if len(objectMetadata) == 0 {
-		return iodine.New(errors.New("invalid argument"), nil)
+		return iodine.New(InvalidArgument{}, nil)
 	}
 	objectMetadataWriters, err := b.getDiskWriters(objectName, donutObjectMetadataConfig)
 	if err != nil {
@@ -112,12 +111,12 @@ func (b bucket) normalizeObjectName(objectName string) string {
 // getDataAndParity - calculate k, m (data and parity) values from number of disks
 func (b bucket) getDataAndParity(totalWriters int) (k uint8, m uint8, err error) {
 	if totalWriters <= 1 {
-		return 0, 0, iodine.New(errors.New("invalid argument"), nil)
+		return 0, 0, iodine.New(InvalidArgument{}, nil)
 	}
 	quotient := totalWriters / 2 // not using float or abs to let integer round off to lower value
 	// quotient cannot be bigger than (255 / 2) = 127
 	if quotient > 127 {
-		return 0, 0, iodine.New(errors.New("parity over flow"), nil)
+		return 0, 0, iodine.New(ParityOverflow{}, nil)
 	}
 	remainder := totalWriters % 2 // will be 1 for odd and 0 for even numbers
 	k = uint8(quotient + remainder)
@@ -174,8 +173,7 @@ func (b bucket) readEncodedData(objectName string, writer *io.PipeWriter, donutO
 		}
 		technique, ok := donutObjectMetadata["sys.erasureTechnique"]
 		if !ok {
-			err := errors.New("missing erasure Technique")
-			writer.CloseWithError(iodine.New(err, nil))
+			writer.CloseWithError(iodine.New(MissingErasureTechnique{}, nil))
 			return
 		}
 		encoder, err := NewEncoder(uint8(k), uint8(m), technique)
@@ -205,8 +203,7 @@ func (b bucket) readEncodedData(objectName string, writer *io.PipeWriter, donutO
 	}
 	// check if decodedData md5sum matches
 	if !bytes.Equal(expectedMd5sum, hasher.Sum(nil)) {
-		err := errors.New("checksum mismatch")
-		writer.CloseWithError(iodine.New(err, nil))
+		writer.CloseWithError(iodine.New(ChecksumMismatch{}, nil))
 		return
 	}
 	writer.Close()

pkg/storage/donut/donut_disk_darwin.go

@@ -17,9 +17,9 @@
 package donut
 
 import (
-	"errors"
 	"os"
 	"path/filepath"
+	"strconv"
 	"syscall"
 
 	"io/ioutil"
@@ -37,7 +37,7 @@ type disk struct {
 // NewDisk - instantiate new disk
 func NewDisk(diskPath string, diskOrder int) (Disk, error) {
 	if diskPath == "" || diskOrder < 0 {
-		return nil, iodine.New(errors.New("invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	s := syscall.Statfs_t{}
 	err := syscall.Statfs(diskPath, &s)
@@ -61,7 +61,9 @@ func NewDisk(diskPath string, diskOrder int) (Disk, error) {
 		d.filesystem["MountPoint"] = d.root
 		return d, nil
 	}
-	return nil, iodine.New(errors.New("unsupported filesystem"), nil)
+	return nil, iodine.New(UnsupportedFilesystem{
+		Type: strconv.FormatInt(s.Type, 10),
+	}, map[string]string{"Type": strconv.FormatInt(s.Type, 10)})
 }
 
 // GetPath - get root disk path
@@ -126,7 +128,7 @@ func (d disk) ListFiles(dirname string) ([]os.FileInfo, error) {
 // MakeFile - create a file inside disk root path
 func (d disk) MakeFile(filename string) (*os.File, error) {
 	if filename == "" {
-		return nil, iodine.New(errors.New("Invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	filePath := filepath.Join(d.root, filename)
 	// Create directories if they don't exist
@@ -143,7 +145,7 @@ func (d disk) MakeFile(filename string) (*os.File, error) {
 // OpenFile - read a file inside disk root path
 func (d disk) OpenFile(filename string) (*os.File, error) {
 	if filename == "" {
-		return nil, iodine.New(errors.New("Invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	dataFile, err := os.Open(filepath.Join(d.root, filename))
 	if err != nil {

pkg/storage/donut/donut_disk_linux.go

@@ -17,9 +17,9 @@
 package donut
 
 import (
-	"errors"
 	"os"
 	"path/filepath"
+	"strconv"
 	"syscall"
 
 	"io/ioutil"
@@ -37,7 +37,7 @@ type disk struct {
 // NewDisk - instantiate new disk
 func NewDisk(diskPath string, diskOrder int) (Disk, error) {
 	if diskPath == "" || diskOrder < 0 {
-		return nil, iodine.New(errors.New("invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	s := syscall.Statfs_t{}
 	err := syscall.Statfs(diskPath, &s)
@@ -61,7 +61,9 @@ func NewDisk(diskPath string, diskOrder int) (Disk, error) {
 		d.filesystem["MountPoint"] = d.root
 		return d, nil
 	}
-	return nil, iodine.New(errors.New("unsupported filesystem"), nil)
+	return nil, iodine.New(UnsupportedFilesystem{
+		Type: strconv.FormatInt(s.Type, 10),
+	}, map[string]string{"Type": strconv.FormatInt(s.Type, 10)})
 }
 
 // GetPath - get root disk path
@@ -126,7 +128,7 @@ func (d disk) ListFiles(dirname string) ([]os.FileInfo, error) {
 // MakeFile - create a file inside disk root path
 func (d disk) MakeFile(filename string) (*os.File, error) {
 	if filename == "" {
-		return nil, iodine.New(errors.New("Invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	filePath := filepath.Join(d.root, filename)
 	// Create directories if they don't exist
@@ -143,7 +145,7 @@ func (d disk) MakeFile(filename string) (*os.File, error) {
 // OpenFile - read a file inside disk root path
 func (d disk) OpenFile(filename string) (*os.File, error) {
 	if filename == "" {
-		return nil, iodine.New(errors.New("Invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	dataFile, err := os.Open(filepath.Join(d.root, filename))
 	if err != nil {

pkg/storage/donut/donut_encoder.go

@@ -17,7 +17,6 @@
 package donut
 
 import (
-	"errors"
 	"strconv"
 
 	encoding "github.com/minio/minio/pkg/erasure"
@@ -39,7 +38,7 @@ func getErasureTechnique(technique string) (encoding.Technique, error) {
 	case technique == "Vandermonde":
 		return encoding.Cauchy, nil
 	default:
-		return encoding.None, iodine.New(errors.New("Invalid erasure technique"), nil)
+		return encoding.None, iodine.New(InvalidErasureTechnique{Technique: technique}, nil)
 	}
 }
 
@@ -70,7 +69,7 @@ func NewEncoder(k, m uint8, technique string) (Encoder, error) {
 // GetEncodedBlockLen - wrapper around erasure function with the same name
 func (e encoder) GetEncodedBlockLen(dataLength int) (int, error) {
 	if dataLength <= 0 {
-		return 0, iodine.New(errors.New("invalid argument"), nil)
+		return 0, iodine.New(InvalidArgument{}, nil)
 	}
 	return encoding.GetEncodedBlockLen(dataLength, e.k), nil
 }
@@ -78,7 +77,7 @@ func (e encoder) GetEncodedBlockLen(dataLength int) (int, error) {
 // Encode - erasure code input bytes
 func (e encoder) Encode(data []byte) (encodedData [][]byte, err error) {
 	if data == nil {
-		return nil, iodine.New(errors.New("invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	encodedData, err = e.encoder.Encode(data)
 	if err != nil {

pkg/storage/donut/donut_errors.go

@@ -0,0 +1,140 @@
+/*
+ * Minimalist Object Storage, (C) 2015 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package donut
+
+// InvalidArgument invalid argument
+type InvalidArgument struct{}
+
+func (e InvalidArgument) Error() string {
+	return "Invalid argument"
+}
+
+// UnsupportedFilesystem unsupported filesystem type
+type UnsupportedFilesystem struct {
+	Type string
+}
+
+func (e UnsupportedFilesystem) Error() string {
+	return "Unsupported filesystem: " + e.Type
+}
+
+// BucketNotFound bucket does not exist
+type BucketNotFound struct {
+	Bucket string
+}
+
+func (e BucketNotFound) Error() string {
+	return "Bucket not found: " + e.Bucket
+}
+
+// ObjectExists object exists
+type ObjectExists struct {
+	Object string
+}
+
+func (e ObjectExists) Error() string {
+	return "Object exists: " + e.Object
+}
+
+// ObjectNotFound object does not exist
+type ObjectNotFound struct {
+	Object string
+}
+
+func (e ObjectNotFound) Error() string {
+	return "Object not found: " + e.Object
+}
+
+// ObjectCorrupted object found to be corrupted
+type ObjectCorrupted struct {
+	Object string
+}
+
+func (e ObjectCorrupted) Error() string {
+	return "Object found corrupted: " + e.Object
+}
+
+// BucketExists bucket exists
+type BucketExists struct {
+	Bucket string
+}
+
+func (e BucketExists) Error() string {
+	return "Bucket exists: " + e.Bucket
+}
+
+// CorruptedBackend backend found to be corrupted
+type CorruptedBackend struct {
+	Backend string
+}
+
+func (e CorruptedBackend) Error() string {
+	return "Corrupted backend: " + e.Backend
+}
+
+// NotImplemented function not implemented
+type NotImplemented struct {
+	Function string
+}
+
+func (e NotImplemented) Error() string {
+	return "Not implemented: " + e.Function
+}
+
+// InvalidDisksArgument invalid number of disks per node
+type InvalidDisksArgument struct{}
+
+func (e InvalidDisksArgument) Error() string {
+	return "Invalid number of disks per node"
+}
+
+// BadDigest bad md5sum
+type BadDigest struct{}
+
+func (e BadDigest) Error() string {
+	return "Bad digest"
+}
+
+// ParityOverflow parity over flow
+type ParityOverflow struct{}
+
+func (e ParityOverflow) Error() string {
+	return "Parity overflow"
+}
+
+// ChecksumMismatch checksum mismatch
+type ChecksumMismatch struct{}
+
+func (e ChecksumMismatch) Error() string {
+	return "Checksum mismatch"
+}
+
+// MissingErasureTechnique missing erasure technique
+type MissingErasureTechnique struct{}
+
+func (e MissingErasureTechnique) Error() string {
+	return "Missing erasure technique"
+}
+
+// InvalidErasureTechnique invalid erasure technique
+type InvalidErasureTechnique struct {
+	Technique string
+}
+
+func (e InvalidErasureTechnique) Error() string {
+	return "Invalid erasure technique: " + e.Technique
+}

pkg/storage/donut/donut_node.go

@@ -16,11 +16,7 @@
 
 package donut
 
-import (
-	"errors"
-
-	"github.com/minio/minio/pkg/iodine"
-)
+import "github.com/minio/minio/pkg/iodine"
 
 // node struct internal
 type node struct {
@@ -31,7 +27,7 @@ type node struct {
 // NewNode - instantiates a new node
 func NewNode(hostname string) (Node, error) {
 	if hostname == "" {
-		return nil, iodine.New(errors.New("invalid argument"), nil)
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	disks := make(map[string]Disk)
 	n := node{
@@ -54,7 +50,7 @@ func (n node) ListDisks() (map[string]Disk, error) {
 // AttachDisk - attach a disk
 func (n node) AttachDisk(disk Disk) error {
 	if disk == nil {
-		return iodine.New(errors.New("Invalid argument"), nil)
+		return iodine.New(InvalidArgument{}, nil)
 	}
 	n.disks[disk.GetPath()] = disk
 	return nil
@@ -68,10 +64,10 @@ func (n node) DetachDisk(disk Disk) error {
 
 // SaveConfig - save node configuration
 func (n node) SaveConfig() error {
-	return errors.New("Not Implemented")
+	return iodine.New(NotImplemented{Function: "SaveConfig"}, nil)
 }
 
 // LoadConfig - load node configuration from saved configs
 func (n node) LoadConfig() error {
-	return errors.New("Not Implemented")
+	return iodine.New(NotImplemented{Function: "LoadConfig"}, nil)
 }

pkg/storage/donut/donut_object.go

@@ -18,9 +18,10 @@ package donut
 
 import (
 	"encoding/json"
-	"errors"
 	"io/ioutil"
 	"path/filepath"
+
+	"github.com/minio/minio/pkg/iodine"
 )
 
 // object internal struct
@@ -34,7 +35,7 @@ type object struct {
 // NewObject - instantiate a new object
 func NewObject(objectName, p string) (Object, error) {
 	if objectName == "" {
-		return nil, errors.New("invalid argument")
+		return nil, iodine.New(InvalidArgument{}, nil)
 	}
 	o := object{}
 	o.name = objectName
@@ -46,10 +47,10 @@ func (o object) GetObjectMetadata() (map[string]string, error) {
 	objectMetadata := make(map[string]string)
 	objectMetadataBytes, err := ioutil.ReadFile(filepath.Join(o.objectPath, objectMetadataConfig))
 	if err != nil {
-		return nil, err
+		return nil, iodine.New(err, nil)
 	}
 	if err := json.Unmarshal(objectMetadataBytes, &objectMetadata); err != nil {
-		return nil, err
+		return nil, iodine.New(err, nil)
 	}
 	o.objectMetadata = objectMetadata
 	return o.objectMetadata, nil
@@ -59,10 +60,10 @@ func (o object) GetDonutObjectMetadata() (map[string]string, error) {
 	donutObjectMetadata := make(map[string]string)
 	donutObjectMetadataBytes, err := ioutil.ReadFile(filepath.Join(o.objectPath, donutObjectMetadataConfig))
 	if err != nil {
-		return nil, err
+		return nil, iodine.New(err, nil)
 	}
 	if err := json.Unmarshal(donutObjectMetadataBytes, &donutObjectMetadata); err != nil {
-		return nil, err
+		return nil, iodine.New(err, nil)
 	}
 	o.donutObjectMetadata = donutObjectMetadata
 	return o.donutObjectMetadata, nil

pkg/storage/donut/management.go

@@ -2,7 +2,6 @@ package donut
 
 import (
 	"encoding/json"
-	"errors"
 	"path/filepath"
 
 	"github.com/minio/minio/pkg/iodine"
@@ -10,7 +9,7 @@ import (
 
 // Heal - heal a donut and fix bad data blocks
 func (d donut) Heal() error {
-	return errors.New("Not Implemented")
+	return iodine.New(NotImplemented{Function: "Heal"}, nil)
 }
 
 // Info - return info about donut configuration
@@ -33,7 +32,7 @@ func (d donut) Info() (nodeDiskMap map[string][]string, err error) {
 // AttachNode - attach node
 func (d donut) AttachNode(node Node) error {
 	if node == nil {
-		return iodine.New(errors.New("invalid argument"), nil)
+		return iodine.New(InvalidArgument{}, nil)
 	}
 	d.nodes[node.GetNodeName()] = node
 	return nil
@@ -72,5 +71,5 @@ func (d donut) SaveConfig() error {
 
 // LoadConfig - load configuration
 func (d donut) LoadConfig() error {
-	return errors.New("Not Implemented")
+	return iodine.New(NotImplemented{Function: "LoadConfig"}, nil)
 }

pkg/storage/donut/objectstorage.go

@@ -17,7 +17,6 @@
 package donut
 
 import (
-	"errors"
 	"io"
 	"sort"
 	"strconv"
@@ -29,7 +28,7 @@ import (
 // MakeBucket - make a new bucket
 func (d donut) MakeBucket(bucket, acl string) error {
 	if bucket == "" || strings.TrimSpace(bucket) == "" {
-		return iodine.New(errors.New("invalid argument"), nil)
+		return iodine.New(InvalidArgument{}, nil)
 	}
 	return d.makeDonutBucket(bucket, acl)
 }
@@ -41,7 +40,7 @@ func (d donut) GetBucketMetadata(bucket string) (map[string]string, error) {
 		return nil, iodine.New(err, nil)
 	}
 	if _, ok := d.buckets[bucket]; !ok {
-		return nil, iodine.New(errors.New("bucket does not exist"), nil)
+		return nil, iodine.New(BucketNotFound{Bucket: bucket}, nil)
 	}
 	metadata, err := d.getDonutBucketMetadata()
 	if err != nil {
@@ -98,7 +97,7 @@ func (d donut) ListObjects(bucket, prefix, marker, delimiter string, maxkeys int
 		return nil, nil, false, iodine.New(err, errParams)
 	}
 	if _, ok := d.buckets[bucket]; !ok {
-		return nil, nil, false, iodine.New(errors.New("bucket does not exist"), errParams)
+		return nil, nil, false, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
 	}
 	objectList, err := d.buckets[bucket].ListObjects()
 	if err != nil {
@@ -165,17 +164,17 @@ func (d donut) PutObject(bucket, object, expectedMD5Sum string, reader io.ReadCl
 		"object": object,
 	}
 	if bucket == "" || strings.TrimSpace(bucket) == "" {
-		return "", iodine.New(errors.New("invalid argument"), errParams)
+		return "", iodine.New(InvalidArgument{}, errParams)
 	}
 	if object == "" || strings.TrimSpace(object) == "" {
-		return "", iodine.New(errors.New("invalid argument"), errParams)
+		return "", iodine.New(InvalidArgument{}, errParams)
 	}
 	err := d.getDonutBuckets()
 	if err != nil {
 		return "", iodine.New(err, errParams)
 	}
 	if _, ok := d.buckets[bucket]; !ok {
-		return "", iodine.New(errors.New("bucket does not exist"), nil)
+		return "", iodine.New(BucketNotFound{Bucket: bucket}, nil)
 	}
 	objectList, err := d.buckets[bucket].ListObjects()
 	if err != nil {
@@ -183,7 +182,7 @@ func (d donut) PutObject(bucket, object, expectedMD5Sum string, reader io.ReadCl
 	}
 	for objectName := range objectList {
 		if objectName == object {
-			return "", iodine.New(errors.New("object exists"), nil)
+			return "", iodine.New(ObjectExists{Object: object}, nil)
 		}
 	}
 	md5sum, err := d.buckets[bucket].PutObject(object, reader, expectedMD5Sum, metadata)
@@ -200,17 +199,17 @@ func (d donut) GetObject(bucket, object string) (reader io.ReadCloser, size int6
 		"object": object,
 	}
 	if bucket == "" || strings.TrimSpace(bucket) == "" {
-		return nil, 0, iodine.New(errors.New("invalid argument"), errParams)
+		return nil, 0, iodine.New(InvalidArgument{}, errParams)
 	}
 	if object == "" || strings.TrimSpace(object) == "" {
-		return nil, 0, iodine.New(errors.New("invalid argument"), errParams)
+		return nil, 0, iodine.New(InvalidArgument{}, errParams)
 	}
 	err = d.getDonutBuckets()
 	if err != nil {
 		return nil, 0, iodine.New(err, nil)
 	}
 	if _, ok := d.buckets[bucket]; !ok {
-		return nil, 0, iodine.New(errors.New("bucket does not exist"), errParams)
+		return nil, 0, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
 	}
 	objectList, err := d.buckets[bucket].ListObjects()
 	if err != nil {
@@ -221,7 +220,7 @@ func (d donut) GetObject(bucket, object string) (reader io.ReadCloser, size int6
 			return d.buckets[bucket].GetObject(object)
 		}
 	}
-	return nil, 0, iodine.New(errors.New("object not found"), nil)
+	return nil, 0, iodine.New(ObjectNotFound{Object: object}, nil)
 }
 
 // GetObjectMetadata - get object metadata
@@ -235,7 +234,7 @@ func (d donut) GetObjectMetadata(bucket, object string) (map[string]string, erro
 		return nil, iodine.New(err, errParams)
 	}
 	if _, ok := d.buckets[bucket]; !ok {
-		return nil, iodine.New(errors.New("bucket does not exist"), errParams)
+		return nil, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
 	}
 	objectList, err := d.buckets[bucket].ListObjects()
 	if err != nil {
@@ -243,7 +242,7 @@ func (d donut) GetObjectMetadata(bucket, object string) (map[string]string, erro
 	}
 	donutObject, ok := objectList[object]
 	if !ok {
-		return nil, iodine.New(errors.New("object does not exist"), errParams)
+		return nil, iodine.New(ObjectNotFound{Object: object}, errParams)
 	}
 	return donutObject.GetObjectMetadata()
 }

pkg/storage/donut/objectstorage_internal.go

@@ -18,7 +18,6 @@ package donut
 
 import (
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -111,7 +110,7 @@ func (d donut) makeDonutBucket(bucketName, acl string) error {
 		return iodine.New(err, nil)
 	}
 	if _, ok := d.buckets[bucketName]; ok {
-		return iodine.New(errors.New("bucket exists"), nil)
+		return iodine.New(BucketExists{Bucket: bucketName}, nil)
 	}
 	bucket, bucketMetadata, err := NewBucket(bucketName, acl, d.name, d.nodes)
 	if err != nil {
@@ -169,7 +168,7 @@ func (d donut) getDonutBuckets() error {
 			for _, dir := range dirs {
 				splitDir := strings.Split(dir.Name(), "$")
 				if len(splitDir) < 3 {
-					return iodine.New(errors.New("corrupted backend"), nil)
+					return iodine.New(CorruptedBackend{Backend: dir.Name()}, nil)
 				}
 				bucketName := splitDir[0]
 				// we dont need this NewBucket once we cache from makeDonutBucket()

pkg/storage/drivers/donut/donut.go

@@ -29,8 +29,6 @@ import (
 
 	"io/ioutil"
 
-	"errors"
-
 	"github.com/minio/minio/pkg/iodine"
 	"github.com/minio/minio/pkg/storage/donut"
 	"github.com/minio/minio/pkg/storage/drivers"
@@ -430,25 +428,25 @@ func (d donutDriver) CreateObject(bucketName, objectName, contentType, expectedM
 }
 
 func (d donutDriver) ListMultipartUploads(bucket string, resources drivers.BucketMultipartResourcesMetadata) (drivers.BucketMultipartResourcesMetadata, error) {
-	return drivers.BucketMultipartResourcesMetadata{}, iodine.New(errors.New("Not Implemented"), nil)
+	return drivers.BucketMultipartResourcesMetadata{}, iodine.New(drivers.APINotImplemented{API: "ListMultipartUploads"}, nil)
 }
 
 func (d donutDriver) NewMultipartUpload(bucket, key, contentType string) (string, error) {
-	return "", iodine.New(errors.New("Not Implemented"), nil)
+	return "", iodine.New(drivers.APINotImplemented{API: "NewMultipartUpload"}, nil)
 }
 
 func (d donutDriver) CreateObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader) (string, error) {
-	return "", iodine.New(errors.New("Not Implemented"), nil)
+	return "", iodine.New(drivers.APINotImplemented{API: "CreateObjectPart"}, nil)
 }
 
 func (d donutDriver) CompleteMultipartUpload(bucket, key, uploadID string, parts map[int]string) (string, error) {
-	return "", iodine.New(errors.New("Not Implemented"), nil)
+	return "", iodine.New(drivers.APINotImplemented{API: "CompleteMultipartUpload"}, nil)
 }
 
 func (d donutDriver) ListObjectParts(bucket, key string, resources drivers.ObjectResourcesMetadata) (drivers.ObjectResourcesMetadata, error) {
-	return drivers.ObjectResourcesMetadata{}, iodine.New(errors.New("Not Implemented"), nil)
+	return drivers.ObjectResourcesMetadata{}, iodine.New(drivers.APINotImplemented{API: "ListObjectParts"}, nil)
 }
 
 func (d donutDriver) AbortMultipartUpload(bucket, key, uploadID string) error {
-	return iodine.New(errors.New("Not Implemented"), nil)
+	return iodine.New(drivers.APINotImplemented{API: "AbortMultipartUpload"}, nil)
 }