api: Various fixes.

- limit list buckets to limit only 100 buckets, all uppercase buckets
  are now lowercase and work transparently with all calls.
- Change disk.Stat to disk.GetInfo and return back disk.Info{} struct.
- Introduce new ioutils package which implements ReadDirN(path, n),
  ReadDirNamesN(path, n)

pkg/disk/disk.go

@@ -16,11 +16,11 @@
 
 package disk
 
-// StatFS stat fs struct is container which holds following values
+// Info stat fs struct is container which holds following values
 // Total - total size of the volume / disk
 // Free - free size of the volume / disk
-// FSType - file system type string
-type StatFS struct {
+// Type - file system type string
+type Info struct {
 	Total  int64
 	Free   int64
 	FSType string

pkg/disk/disk_test.go

@@ -36,9 +36,9 @@ func (s *MySuite) TestFree(c *C) {
 	path, err := ioutil.TempDir(os.TempDir(), "minio-")
 	c.Assert(err, IsNil)
 
-	statfs, err := disk.Stat(path)
+	di, err := disk.GetInfo(path)
 	c.Assert(err, IsNil)
-	c.Assert(statfs.Total, Not(Equals), 0)
-	c.Assert(statfs.Free, Not(Equals), 0)
-	c.Assert(statfs.FSType, Not(Equals), "UNKNOWN")
+	c.Assert(di.Total, Not(Equals), 0)
+	c.Assert(di.Free, Not(Equals), 0)
+	c.Assert(di.FSType, Not(Equals), "UNKNOWN")
 }

pkg/disk/stat_nix.go

@@ -22,19 +22,19 @@ import (
 	"syscall"
 )
 
-// Stat returns total and free bytes available in a directory, e.g. `/`.
-func Stat(path string) (statfs StatFS, err error) {
+// GetInfo returns total and free bytes available in a directory, e.g. `/`.
+func GetInfo(path string) (info Info, err error) {
 	s := syscall.Statfs_t{}
 	err = syscall.Statfs(path, &s)
 	if err != nil {
-		return StatFS{}, err
+		return Info{}, err
 	}
-	statfs = StatFS{}
-	statfs.Total = int64(s.Bsize) * int64(s.Blocks)
-	statfs.Free = int64(s.Bsize) * int64(s.Bfree)
-	statfs.FSType, err = getFSType(path)
+	info = Info{}
+	info.Total = int64(s.Bsize) * int64(s.Blocks)
+	info.Free = int64(s.Bsize) * int64(s.Bfree)
+	info.FSType, err = getFSType(path)
 	if err != nil {
-		return StatFS{}, err
+		return Info{}, err
 	}
-	return statfs, nil
+	return info, nil
 }

pkg/disk/stat_windows.go

@@ -23,11 +23,11 @@ import (
 	"unsafe"
 )
 
-// Stat returns total and free bytes available in a directory, e.g. `C:\`.
+// GetInfo returns total and free bytes available in a directory, e.g. `C:\`.
 // It returns free space available to the user (including quota limitations)
 //
 // https://msdn.microsoft.com/en-us/library/windows/desktop/aa364937(v=vs.85).aspx
-func Stat(path string) (statfs StatFS, err error) {
+func GetInfo(path string) (info Info, err error) {
 	dll := syscall.MustLoadDLL("kernel32.dll")
 	// https://msdn.microsoft.com/en-us/library/windows/desktop/aa364937(v=vs.85).aspx
 	// Retrieves information about the amount of space that is available on a disk volume,
@@ -50,9 +50,9 @@ func Stat(path string) (statfs StatFS, err error) {
 		uintptr(unsafe.Pointer(&lpFreeBytesAvailable)),
 		uintptr(unsafe.Pointer(&lpTotalNumberOfBytes)),
 		uintptr(unsafe.Pointer(&lpTotalNumberOfFreeBytes)))
-	statfs = StatFS{}
-	statfs.Total = int64(lpTotalNumberOfBytes)
-	statfs.Free = int64(lpFreeBytesAvailable)
-	statfs.FSType = getFSType(path)
-	return statfs, nil
+	info = Info{}
+	info.Total = int64(lpTotalNumberOfBytes)
+	info.Free = int64(lpFreeBytesAvailable)
+	info.FSType = getFSType(path)
+	return info, nil
 }

pkg/fs/definitions.go

@@ -165,6 +165,9 @@ func IsValidBucketACL(acl string) bool {
 	}
 }
 
+// validBucket regexp.
+var validBucket = regexp.MustCompile(`^[a-z0-9][a-z0-9\.\-]{1,61}[a-z0-9]$`)
+
 // IsValidBucketName - verify bucket name in accordance with
 //  - http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingBucket.html
 func IsValidBucketName(bucket string) bool {
@@ -177,12 +180,7 @@ func IsValidBucketName(bucket string) bool {
 	if bucket[0] == '.' || bucket[len(bucket)-1] == '.' {
 		return false
 	}
-	if match, _ := regexp.MatchString("\\.\\.", bucket); match == true {
-		return false
-	}
-	// We don't support buckets with '.' in them
-	match, _ := regexp.MatchString("^[a-zA-Z0-9][a-zA-Z0-9\\-]+[a-zA-Z0-9]$", bucket)
-	return match
+	return validBucket.MatchString(bucket)
 }
 
 // IsValidObjectName - verify object name in accordance with

pkg/fs/fs-bucket-listobjects.go

@@ -38,6 +38,8 @@ func (fs Filesystem) ListObjects(bucket string, resources BucketResourcesMetadat
 		return nil, resources, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: resources.Prefix})
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
+
 	p := bucketDir{}
 	rootPrefix := filepath.Join(fs.path, bucket)
 	// check bucket exists

pkg/fs/fs-bucket.go

@@ -17,13 +17,15 @@
 package fs
 
 import (
-	"io/ioutil"
+	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/minio/minio-xl/pkg/probe"
 	"github.com/minio/minio/pkg/disk"
+	"github.com/minio/minio/pkg/ioutils"
 )
 
 /// Bucket Operations
@@ -36,22 +38,20 @@ func (fs Filesystem) DeleteBucket(bucket string) *probe.Error {
 	if !IsValidBucketName(bucket) {
 		return probe.NewError(BucketNameInvalid{Bucket: bucket})
 	}
+	bucket = fs.denormalizeBucket(bucket)
 	bucketDir := filepath.Join(fs.path, bucket)
 	// check bucket exists
-	if _, err := os.Stat(bucketDir); err != nil {
-		if os.IsNotExist(err) {
+	if _, e := os.Stat(bucketDir); e != nil {
+		if os.IsNotExist(e) {
 			return probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-		return probe.NewError(err)
+		return probe.NewError(e)
 	}
-	if _, ok := fs.buckets.Metadata[bucket]; !ok {
-		return probe.NewError(BucketNotFound{Bucket: bucket})
-	}
-	if err := os.Remove(bucketDir); err != nil {
-		if strings.Contains(err.Error(), "directory not empty") {
+	if e := os.Remove(bucketDir); e != nil {
+		if strings.Contains(e.Error(), "directory not empty") {
 			return probe.NewError(BucketNotEmpty{Bucket: bucket})
 		}
-		return probe.NewError(err)
+		return probe.NewError(e)
 	}
 	delete(fs.buckets.Metadata, bucket)
 	if err := saveBucketsMetadata(fs.buckets); err != nil {
@@ -60,34 +60,50 @@ func (fs Filesystem) DeleteBucket(bucket string) *probe.Error {
 	return nil
 }
 
+func removeDuplicateBuckets(elements []BucketMetadata) (result []BucketMetadata) {
+	// Use map to record duplicates as we find them.
+	duplicates := make(map[string]struct{})
+	for _, element := range elements {
+		if _, ok := duplicates[element.Name]; !ok {
+			duplicates[element.Name] = struct{}{}
+			result = append(result, element)
+		}
+	}
+	return result
+}
+
 // ListBuckets - Get service
 func (fs Filesystem) ListBuckets() ([]BucketMetadata, *probe.Error) {
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
 
-	files, err := ioutil.ReadDir(fs.path)
-	if err != nil {
+	files, err := ioutils.ReadDirN(fs.path, fs.maxBuckets)
+	if err != nil && err != io.EOF {
 		return []BucketMetadata{}, probe.NewError(err)
 	}
-
+	if err == io.EOF {
+		fmt.Printf("Truncating the bucket list to %d entries only.", fs.maxBuckets)
+	}
 	var metadataList []BucketMetadata
 	for _, file := range files {
 		if !file.IsDir() {
 			// if files found ignore them
 			continue
 		}
+		dirName := strings.ToLower(file.Name())
 		if file.IsDir() {
 			// if directories found with odd names, skip them too
-			if !IsValidBucketName(file.Name()) {
+			if !IsValidBucketName(dirName) {
 				continue
 			}
 		}
 		metadata := BucketMetadata{
-			Name:    file.Name(),
+			Name:    dirName,
 			Created: file.ModTime(),
 		}
 		metadataList = append(metadataList, metadata)
 	}
+	metadataList = removeDuplicateBuckets(metadataList)
 	return metadataList, nil
 }
 
@@ -96,13 +112,13 @@ func (fs Filesystem) MakeBucket(bucket, acl string) *probe.Error {
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
 
-	stfs, err := disk.Stat(fs.path)
+	di, err := disk.GetInfo(fs.path)
 	if err != nil {
 		return probe.NewError(err)
 	}
 
 	// Remove 5% from total space for cumulative disk space used for journalling, inodes etc.
-	availableDiskSpace := (float64(stfs.Free) / (float64(stfs.Total) - (0.05 * float64(stfs.Total)))) * 100
+	availableDiskSpace := (float64(di.Free) / (float64(di.Total) - (0.05 * float64(di.Total)))) * 100
 	if int64(availableDiskSpace) <= fs.minFreeDisk {
 		return probe.NewError(RootPathFull{Path: fs.path})
 	}
@@ -116,29 +132,26 @@ func (fs Filesystem) MakeBucket(bucket, acl string) *probe.Error {
 		return probe.NewError(InvalidACL{ACL: acl})
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
 	// get bucket path
 	bucketDir := filepath.Join(fs.path, bucket)
-	// check if bucket exists
-	if _, err = os.Stat(bucketDir); err == nil {
-		return probe.NewError(BucketExists{
-			Bucket: bucket,
-		})
+	if _, e := os.Stat(bucketDir); e == nil {
+		return probe.NewError(BucketExists{Bucket: bucket})
 	}
 
 	// make bucket
-	err = os.Mkdir(bucketDir, 0700)
-	if err != nil {
+	if e := os.Mkdir(bucketDir, 0700); e != nil {
 		return probe.NewError(err)
 	}
 
 	bucketMetadata := &BucketMetadata{}
-	fi, err := os.Stat(bucketDir)
+	fi, e := os.Stat(bucketDir)
 	// check if bucket exists
-	if err != nil {
-		if os.IsNotExist(err) {
+	if e != nil {
+		if os.IsNotExist(e) {
 			return probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-		return probe.NewError(err)
+		return probe.NewError(e)
 	}
 	if strings.TrimSpace(acl) == "" {
 		acl = "private"
@@ -153,6 +166,19 @@ func (fs Filesystem) MakeBucket(bucket, acl string) *probe.Error {
 	return nil
 }
 
+func (fs Filesystem) denormalizeBucket(bucket string) string {
+	buckets, err := ioutils.ReadDirNamesN(fs.path, fs.maxBuckets)
+	if err != nil {
+		return bucket
+	}
+	for _, b := range buckets {
+		if strings.ToLower(b) == bucket {
+			return b
+		}
+	}
+	return bucket
+}
+
 // GetBucketMetadata - get bucket metadata
 func (fs Filesystem) GetBucketMetadata(bucket string) (BucketMetadata, *probe.Error) {
 	fs.lock.Lock()
@@ -160,15 +186,18 @@ func (fs Filesystem) GetBucketMetadata(bucket string) (BucketMetadata, *probe.Er
 	if !IsValidBucketName(bucket) {
 		return BucketMetadata{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
 	}
+
+	bucket = fs.denormalizeBucket(bucket)
+
 	// get bucket path
 	bucketDir := filepath.Join(fs.path, bucket)
-	fi, err := os.Stat(bucketDir)
-	if err != nil {
+	fi, e := os.Stat(bucketDir)
+	if e != nil {
 		// check if bucket exists
-		if os.IsNotExist(err) {
+		if os.IsNotExist(e) {
 			return BucketMetadata{}, probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-		return BucketMetadata{}, probe.NewError(err)
+		return BucketMetadata{}, probe.NewError(e)
 	}
 	bucketMetadata, ok := fs.buckets.Metadata[bucket]
 	if !ok {
@@ -194,14 +223,15 @@ func (fs Filesystem) SetBucketMetadata(bucket string, metadata map[string]string
 	if strings.TrimSpace(acl) == "" {
 		acl = "private"
 	}
+	bucket = fs.denormalizeBucket(bucket)
 	bucketDir := filepath.Join(fs.path, bucket)
-	fi, err := os.Stat(bucketDir)
-	if err != nil {
+	fi, e := os.Stat(bucketDir)
+	if e != nil {
 		// check if bucket exists
-		if os.IsNotExist(err) {
+		if os.IsNotExist(e) {
 			return probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-		return probe.NewError(err)
+		return probe.NewError(e)
 	}
 	bucketMetadata, ok := fs.buckets.Metadata[bucket]
 	if !ok {

pkg/fs/fs-multipart.go

@@ -59,14 +59,14 @@ func (fs Filesystem) ListMultipartUploads(bucket string, resources BucketMultipa
 	if !IsValidBucketName(bucket) {
 		return BucketMultipartResourcesMetadata{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
 	}
+	bucket = fs.denormalizeBucket(bucket)
 	bucketPath := filepath.Join(fs.path, bucket)
-	_, err := os.Stat(bucketPath)
+	if _, e := os.Stat(bucketPath); e != nil {
 		// check bucket exists
-	if os.IsNotExist(err) {
+		if os.IsNotExist(e) {
 			return BucketMultipartResourcesMetadata{}, probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-	if err != nil {
-		return BucketMultipartResourcesMetadata{}, probe.NewError(InternalError{})
+		return BucketMultipartResourcesMetadata{}, probe.NewError(e)
 	}
 	var uploads []*UploadMetadata
 	for object, session := range fs.multiparts.ActiveSession {
@@ -142,13 +142,13 @@ func (fs Filesystem) NewMultipartUpload(bucket, object string) (string, *probe.E
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
 
-	stfs, err := disk.Stat(fs.path)
-	if err != nil {
-		return "", probe.NewError(err)
+	di, e := disk.GetInfo(fs.path)
+	if e != nil {
+		return "", probe.NewError(e)
 	}
 
 	// Remove 5% from total space for cumulative disk space used for journalling, inodes etc.
-	availableDiskSpace := (float64(stfs.Free) / (float64(stfs.Total) - (0.05 * float64(stfs.Total)))) * 100
+	availableDiskSpace := (float64(di.Free) / (float64(di.Total) - (0.05 * float64(di.Total)))) * 100
 	if int64(availableDiskSpace) <= fs.minFreeDisk {
 		return "", probe.NewError(RootPathFull{Path: fs.path})
 	}
@@ -160,31 +160,35 @@ func (fs Filesystem) NewMultipartUpload(bucket, object string) (string, *probe.E
 		return "", probe.NewError(ObjectNameInvalid{Object: object})
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
 	bucketPath := filepath.Join(fs.path, bucket)
-	_, err = os.Stat(bucketPath)
+	if _, e := os.Stat(bucketPath); e != nil {
 		// check bucket exists
-	if os.IsNotExist(err) {
+		if os.IsNotExist(e) {
 			return "", probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-	if err != nil {
-		return "", probe.NewError(InternalError{})
+		return "", probe.NewError(e)
 	}
+
 	objectPath := filepath.Join(bucketPath, object)
 	objectDir := filepath.Dir(objectPath)
-	if _, err = os.Stat(objectDir); os.IsNotExist(err) {
-		err = os.MkdirAll(objectDir, 0700)
-		if err != nil {
-			return "", probe.NewError(err)
+	if _, e := os.Stat(objectDir); e != nil {
+		if os.IsNotExist(e) {
+			e = os.MkdirAll(objectDir, 0700)
+			if e != nil {
+				return "", probe.NewError(e)
 			}
 		}
+		return "", probe.NewError(e)
+	}
 
 	id := []byte(strconv.FormatInt(rand.Int63(), 10) + bucket + object + time.Now().String())
 	uploadIDSum := sha512.Sum512(id)
 	uploadID := base64.URLEncoding.EncodeToString(uploadIDSum[:])[:47]
 
-	multiPartfile, err := os.OpenFile(objectPath+"$multiparts", os.O_WRONLY|os.O_CREATE, 0600)
-	if err != nil {
-		return "", probe.NewError(err)
+	multiPartfile, e := os.OpenFile(objectPath+"$multiparts", os.O_WRONLY|os.O_CREATE, 0600)
+	if e != nil {
+		return "", probe.NewError(e)
 	}
 	defer multiPartfile.Close()
 
@@ -197,9 +201,8 @@ func (fs Filesystem) NewMultipartUpload(bucket, object string) (string, *probe.E
 	fs.multiparts.ActiveSession[object] = mpartSession
 
 	encoder := json.NewEncoder(multiPartfile)
-	err = encoder.Encode(mpartSession)
-	if err != nil {
-		return "", probe.NewError(err)
+	if e = encoder.Encode(mpartSession); e != nil {
+		return "", probe.NewError(e)
 	}
 	if err := saveMultipartsSession(fs.multiparts); err != nil {
 		return "", err.Trace()
@@ -219,13 +222,13 @@ func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum s
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
 
-	stfs, err := disk.Stat(fs.path)
+	di, err := disk.GetInfo(fs.path)
 	if err != nil {
 		return "", probe.NewError(err)
 	}
 
 	// Remove 5% from total space for cumulative disk space used for journalling, inodes etc.
-	availableDiskSpace := (float64(stfs.Free) / (float64(stfs.Total) - (0.05 * float64(stfs.Total)))) * 100
+	availableDiskSpace := (float64(di.Free) / (float64(di.Total) - (0.05 * float64(di.Total)))) * 100
 	if int64(availableDiskSpace) <= fs.minFreeDisk {
 		return "", probe.NewError(RootPathFull{Path: fs.path})
 	}
@@ -257,15 +260,14 @@ func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum s
 		expectedMD5Sum = hex.EncodeToString(expectedMD5SumBytes)
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
 	bucketPath := filepath.Join(fs.path, bucket)
 	if _, err = os.Stat(bucketPath); err != nil {
 		// check bucket exists
 		if os.IsNotExist(err) {
 			return "", probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-		if err != nil {
-			return "", probe.NewError(InternalError{})
-		}
+		return "", probe.NewError(err)
 	}
 
 	objectPath := filepath.Join(bucketPath, object)
@@ -357,6 +359,7 @@ func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, da
 		return ObjectMetadata{}, probe.NewError(InvalidUploadID{UploadID: uploadID})
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
 	bucketPath := filepath.Join(fs.path, bucket)
 	if _, err := os.Stat(bucketPath); err != nil {
 		// check bucket exists
@@ -470,14 +473,14 @@ func (fs Filesystem) ListObjectParts(bucket, object string, resources ObjectReso
 		startPartNumber = objectResourcesMetadata.PartNumberMarker
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
 	bucketPath := filepath.Join(fs.path, bucket)
-	_, err := os.Stat(bucketPath)
+	if _, e := os.Stat(bucketPath); e != nil {
 		// check bucket exists
-	if os.IsNotExist(err) {
+		if os.IsNotExist(e) {
 			return ObjectResourcesMetadata{}, probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-	if err != nil {
-		return ObjectResourcesMetadata{}, probe.NewError(InternalError{})
+		return ObjectResourcesMetadata{}, probe.NewError(e)
 	}
 
 	objectPath := filepath.Join(bucketPath, object)
@@ -528,27 +531,26 @@ func (fs Filesystem) AbortMultipartUpload(bucket, object, uploadID string) *prob
 		return probe.NewError(InvalidUploadID{UploadID: uploadID})
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
 	bucketPath := filepath.Join(fs.path, bucket)
-	_, err := os.Stat(bucketPath)
+	if _, e := os.Stat(bucketPath); e != nil {
 		// check bucket exists
-	if os.IsNotExist(err) {
+		if os.IsNotExist(e) {
 			return probe.NewError(BucketNotFound{Bucket: bucket})
 		}
-	if err != nil {
-		return probe.NewError(InternalError{})
+		return probe.NewError(e)
 	}
 
 	objectPath := filepath.Join(bucketPath, object)
 	for _, part := range fs.multiparts.ActiveSession[object].Parts {
-		err = os.RemoveAll(objectPath + fmt.Sprintf("$%d-$multiparts", part.PartNumber))
-		if err != nil {
-			return probe.NewError(err)
+		e := os.RemoveAll(objectPath + fmt.Sprintf("$%d-$multiparts", part.PartNumber))
+		if e != nil {
+			return probe.NewError(e)
 		}
 	}
 	delete(fs.multiparts.ActiveSession, object)
-	err = os.RemoveAll(objectPath + "$multiparts")
-	if err != nil {
-		return probe.NewError(err)
+	if e := os.RemoveAll(objectPath + "$multiparts"); e != nil {
+		return probe.NewError(e)
 	}
 	return nil
 }

pkg/fs/fs-object.go

@@ -52,7 +52,16 @@ func (fs Filesystem) GetObject(w io.Writer, bucket, object string, start, length
 		return 0, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
 	}
 
-	objectPath := filepath.Join(fs.path, bucket, object)
+	bucket = fs.denormalizeBucket(bucket)
+	bucketPath := filepath.Join(fs.path, bucket)
+	if _, e := os.Stat(bucketPath); e != nil {
+		if os.IsNotExist(e) {
+			return 0, probe.NewError(BucketNotFound{Bucket: bucket})
+		}
+		return 0, probe.NewError(e)
+	}
+
+	objectPath := filepath.Join(bucketPath, object)
 	filestat, err := os.Stat(objectPath)
 	switch err := err.(type) {
 	case nil:
@@ -170,13 +179,13 @@ func (fs Filesystem) CreateObject(bucket, object, expectedMD5Sum string, size in
 	fs.lock.Lock()
 	defer fs.lock.Unlock()
 
-	stfs, err := disk.Stat(fs.path)
+	di, err := disk.GetInfo(fs.path)
 	if err != nil {
 		return ObjectMetadata{}, probe.NewError(err)
 	}
 
 	// Remove 5% from total space for cumulative disk space used for journalling, inodes etc.
-	availableDiskSpace := (float64(stfs.Free) / (float64(stfs.Total) - (0.05 * float64(stfs.Total)))) * 100
+	availableDiskSpace := (float64(di.Free) / (float64(di.Total) - (0.05 * float64(di.Total)))) * 100
 	if int64(availableDiskSpace) <= fs.minFreeDisk {
 		return ObjectMetadata{}, probe.NewError(RootPathFull{Path: fs.path})
 	}
@@ -185,17 +194,22 @@ func (fs Filesystem) CreateObject(bucket, object, expectedMD5Sum string, size in
 	if !IsValidBucketName(bucket) {
 		return ObjectMetadata{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
 	}
-	// check bucket exists
-	if _, err = os.Stat(filepath.Join(fs.path, bucket)); os.IsNotExist(err) {
+
+	bucket = fs.denormalizeBucket(bucket)
+	bucketPath := filepath.Join(fs.path, bucket)
+	if _, e := os.Stat(bucketPath); e != nil {
+		if os.IsNotExist(e) {
 			return ObjectMetadata{}, probe.NewError(BucketNotFound{Bucket: bucket})
 		}
+		return ObjectMetadata{}, probe.NewError(e)
+	}
 	// verify object path legal
 	if !IsValidObjectName(object) {
 		return ObjectMetadata{}, probe.NewError(ObjectNameInvalid{Bucket: bucket, Object: object})
 	}
 
 	// get object path
-	objectPath := filepath.Join(fs.path, bucket, object)
+	objectPath := filepath.Join(bucketPath, object)
 	if strings.TrimSpace(expectedMD5Sum) != "" {
 		var expectedMD5SumBytes []byte
 		expectedMD5SumBytes, err = base64.StdEncoding.DecodeString(strings.TrimSpace(expectedMD5Sum))
@@ -308,11 +322,15 @@ func (fs Filesystem) DeleteObject(bucket, object string) *probe.Error {
 		return probe.NewError(BucketNameInvalid{Bucket: bucket})
 	}
 
+	bucket = fs.denormalizeBucket(bucket)
 	bucketPath := filepath.Join(fs.path, bucket)
 	// check bucket exists
-	if _, err := os.Stat(filepath.Join(fs.path, bucket)); os.IsNotExist(err) {
+	if _, e := os.Stat(bucketPath); e != nil {
+		if os.IsNotExist(e) {
 			return probe.NewError(BucketNotFound{Bucket: bucket})
 		}
+		return probe.NewError(e)
+	}
 
 	// verify object path legal
 	if !IsValidObjectName(object) {

pkg/fs/fs.go

@@ -29,6 +29,7 @@ import (
 type Filesystem struct {
 	path        string
 	minFreeDisk int64
+	maxBuckets  int
 	lock        *sync.Mutex
 	multiparts  *Multiparts
 	buckets     *Buckets
@@ -91,11 +92,20 @@ func New(rootPath string) (Filesystem, *probe.Error) {
 			return Filesystem{}, err.Trace()
 		}
 	}
-	a := Filesystem{lock: new(sync.Mutex)}
-	a.path = rootPath
-	a.multiparts = multiparts
-	a.buckets = buckets
-	return a, nil
+	fs := Filesystem{lock: new(sync.Mutex)}
+	fs.path = rootPath
+	fs.multiparts = multiparts
+	fs.buckets = buckets
+
+	/// Defaults
+
+	// maximum buckets to be listed from list buckets.
+	fs.maxBuckets = 100
+	// minium free disk required for i/o operations to succeed.
+	fs.minFreeDisk = 10
+
+	// Return here.
+	return fs, nil
 }
 
 // SetMinFreeDisk - set min free disk
@@ -104,3 +114,13 @@ func (fs *Filesystem) SetMinFreeDisk(minFreeDisk int64) {
 	defer fs.lock.Unlock()
 	fs.minFreeDisk = minFreeDisk
 }
+
+// SetMaxBuckets - set total number of buckets supported, default is 100.
+func (fs *Filesystem) SetMaxBuckets(maxBuckets int) {
+	fs.lock.Lock()
+	defer fs.lock.Unlock()
+	if maxBuckets == 0 {
+		maxBuckets = 100
+	}
+	fs.maxBuckets = maxBuckets
+}

pkg/ioutils/ioutils.go

@@ -0,0 +1,45 @@
+package ioutils
+
+import (
+	"os"
+	"sort"
+)
+
+// byName implements sort.Interface for sorting os.FileInfo list.
+type byName []os.FileInfo
+
+func (f byName) Len() int           { return len(f) }
+func (f byName) Less(i, j int) bool { return f[i].Name() < f[j].Name() }
+func (f byName) Swap(i, j int)      { f[i], f[j] = f[j], f[i] }
+
+// ReadDirN reads the directory named by dirname and returns
+// a list of sorted directory entries of size 'n'.
+func ReadDirN(dirname string, n int) ([]os.FileInfo, error) {
+	f, err := os.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	list, err := f.Readdir(n)
+	f.Close()
+	if err != nil {
+		return nil, err
+	}
+	sort.Sort(byName(list))
+	return list, nil
+}
+
+// ReadDirNamesN reads the directory named by dirname and returns
+// a list of sorted directory names of size 'n'.
+func ReadDirNamesN(dirname string, n int) ([]string, error) {
+	f, err := os.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	names, err := f.Readdirnames(n)
+	f.Close()
+	if err != nil {
+		return nil, err
+	}
+	sort.Strings(names)
+	return names, nil
+}