/*

* Minio Cloud Storage, (C) 2016, 2017, 2018 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 cmd

import (

"context"

"encoding/hex"

"fmt"

"io"

"io/ioutil"

"os"

"path"

"path/filepath"

"reflect"

"sort"

"sync"

"syscall"

"time"

"github.com/minio/minio-go/pkg/policy"

"github.com/minio/minio/pkg/errors"

"github.com/minio/minio/pkg/hash"

"github.com/minio/minio/pkg/lock"

"github.com/minio/minio/pkg/madmin"

)

// FSObjects - Implements fs object layer.

type FSObjects struct {

// Path to be exported over S3 API.

fsPath string

// Unique value to be used for all

// temporary transactions.

fsUUID string

// This value shouldn't be touched, once initialized.

fsFormatRlk *lock.RLockedFile // Is a read lock on `format.json`.

// FS rw pool.

rwPool *fsIOPool

// ListObjects pool management.

listPool *treeWalkPool

appendFileMap map[string]*fsAppendFile

appendFileMapMu sync.Mutex

// To manage the appendRoutine go-routines

nsMutex *nsLockMap

// Variable represents bucket policies in memory.

bucketPolicies *bucketPolicies

}

// Represents the background append file.

type fsAppendFile struct {

sync.Mutex

parts []PartInfo // List of parts appended.

filePath string // Absolute path of the file in the temp location.

}

// Initializes meta volume on all the fs path.

func initMetaVolumeFS(fsPath, fsUUID string) error {

// This happens for the first time, but keep this here since this

// is the only place where it can be made less expensive

// optimizing all other calls. Create minio meta volume,

// if it doesn't exist yet.

metaBucketPath := pathJoin(fsPath, minioMetaBucket)

if err := os.MkdirAll(metaBucketPath, 0777); err != nil {

return err

}

metaTmpPath := pathJoin(fsPath, minioMetaTmpBucket, fsUUID)

if err := os.MkdirAll(metaTmpPath, 0777); err != nil {

return err

}

metaMultipartPath := pathJoin(fsPath, minioMetaMultipartBucket)

return os.MkdirAll(metaMultipartPath, 0777)

}

// NewFSObjectLayer - initialize new fs object layer.

func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {

if fsPath == "" {

return nil, errInvalidArgument

}

var err error

// Disallow relative paths, figure out absolute paths.

fsPath, err = filepath.Abs(fsPath)

if err != nil {

return nil, err

}

fi, err := os.Stat((fsPath))

if err == nil {

if !fi.IsDir() {

return nil, syscall.ENOTDIR

}

}

if os.IsNotExist(err) {

// Disk not found create it.

err = os.MkdirAll(fsPath, 0777)

if err != nil {

return nil, err

}

}

di, err := getDiskInfo((fsPath))

if err != nil {

return nil, err

}

// Check if disk has minimum required total space.

if err = checkDiskMinTotal(di); err != nil {

return nil, err

}

// Assign a new UUID for FS minio mode. Each server instance

// gets its own UUID for temporary file transaction.

fsUUID := mustGetUUID()

// Initialize meta volume, if volume already exists ignores it.

if err = initMetaVolumeFS(fsPath, fsUUID); err != nil {

return nil, fmt.Errorf("Unable to initialize '.minio.sys' meta volume, %s", err)

}

// Initialize `format.json`, this function also returns.

rlk, err := initFormatFS(fsPath)

if err != nil {

return nil, err

}

// Initialize fs objects.

fs := &FSObjects{

fsPath: fsPath,

fsUUID: fsUUID,

rwPool: &fsIOPool{

readersMap: make(map[string]*lock.RLockedFile),

},

nsMutex: newNSLock(false),

listPool: newTreeWalkPool(globalLookupTimeout),

appendFileMap: make(map[string]*fsAppendFile),

}

// Once the filesystem has initialized hold the read lock for

// the life time of the server. This is done to ensure that under

// shared backend mode for FS, remote servers do not migrate

// or cause changes on backend format.

fs.fsFormatRlk = rlk

// Initialize and load bucket policies.

fs.bucketPolicies, err = initBucketPolicies(fs)

if err != nil {

return nil, fmt.Errorf("Unable to load all bucket policies. %s", err)

}

// Initialize notification system.

if err = globalNotificationSys.Init(fs); err != nil {

return nil, fmt.Errorf("Unable to initialize event notification. %s", err)

}

go fs.cleanupStaleMultipartUploads(globalMultipartCleanupInterval, globalMultipartExpiry, globalServiceDoneCh)

// Return successfully initialized object layer.

return fs, nil

}

// Shutdown - should be called when process shuts down.

func (fs *FSObjects) Shutdown(ctx context.Context) error {

fs.fsFormatRlk.Close()

// Cleanup and delete tmp uuid.

return fsRemoveAll(pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID))

}

// StorageInfo - returns underlying storage statistics.

func (fs *FSObjects) StorageInfo(ctx context.Context) StorageInfo {

info, err := getDiskInfo((fs.fsPath))

errorIf(err, "Unable to get disk info %#v", fs.fsPath)

storageInfo := StorageInfo{

Total: info.Total,

Free: info.Free,

}

storageInfo.Backend.Type = FS

return storageInfo

}

// Locking operations

// ListLocks - List namespace locks held in object layer

func (fs *FSObjects) ListLocks(ctx context.Context, bucket, prefix string, duration time.Duration) ([]VolumeLockInfo, error) {

return []VolumeLockInfo{}, NotImplemented{}

}

// ClearLocks - Clear namespace locks held in object layer

func (fs *FSObjects) ClearLocks(ctx context.Context, info []VolumeLockInfo) error {

return NotImplemented{}

}

/// Bucket operations

// getBucketDir - will convert incoming bucket names to

// corresponding valid bucket names on the backend in a platform

// compatible way for all operating systems.

func (fs *FSObjects) getBucketDir(bucket string) (string, error) {

// Verify if bucket is valid.

if !IsValidBucketName(bucket) {

return "", errors.Trace(BucketNameInvalid{Bucket: bucket})

}

bucketDir := pathJoin(fs.fsPath, bucket)

return bucketDir, nil

}

func (fs *FSObjects) statBucketDir(bucket string) (os.FileInfo, error) {

bucketDir, err := fs.getBucketDir(bucket)

if err != nil {

return nil, err

}

st, err := fsStatVolume(bucketDir)

if err != nil {

return nil, err

}

return st, nil

}

// MakeBucketWithLocation - create a new bucket, returns if it

// already exists.

func (fs *FSObjects) MakeBucketWithLocation(ctx context.Context, bucket, location string) error {

bucketLock := fs.nsMutex.NewNSLock(bucket, "")

if err := bucketLock.GetLock(globalObjectTimeout); err != nil {

return err

}

defer bucketLock.Unlock()

bucketDir, err := fs.getBucketDir(bucket)

if err != nil {

return toObjectErr(err, bucket)

}

if err = fsMkdir(bucketDir); err != nil {

return toObjectErr(err, bucket)

}

return nil

}

// GetBucketInfo - fetch bucket metadata info.

func (fs *FSObjects) GetBucketInfo(ctx context.Context, bucket string) (bi BucketInfo, e error) {

bucketLock := fs.nsMutex.NewNSLock(bucket, "")

if e := bucketLock.GetRLock(globalObjectTimeout); e != nil {

return bi, e

}

defer bucketLock.RUnlock()

st, err := fs.statBucketDir(bucket)

if err != nil {

return bi, toObjectErr(err, bucket)

}

// As os.Stat() doesn't carry other than ModTime(), use ModTime() as CreatedTime.

createdTime := st.ModTime()

return BucketInfo{

Name: bucket,

Created: createdTime,

}, nil

}

// ListBuckets - list all s3 compatible buckets (directories) at fsPath.

func (fs *FSObjects) ListBuckets(ctx context.Context) ([]BucketInfo, error) {

if err := checkPathLength(fs.fsPath); err != nil {

return nil, errors.Trace(err)

}

var bucketInfos []BucketInfo

entries, err := readDir((fs.fsPath))

if err != nil {

return nil, toObjectErr(errors.Trace(errDiskNotFound))

}

for _, entry := range entries {

// Ignore all reserved bucket names and invalid bucket names.

if isReservedOrInvalidBucket(entry) {

continue

}

var fi os.FileInfo

fi, err = fsStatVolume(pathJoin(fs.fsPath, entry))

// There seems like no practical reason to check for errors

// at this point, if there are indeed errors we can simply

// just ignore such buckets and list only those which

// return proper Stat information instead.

if err != nil {

// Ignore any errors returned here.

continue

}

bucketInfos = append(bucketInfos, BucketInfo{

Name: fi.Name(),

// As os.Stat() doesnt carry CreatedTime, use ModTime() as CreatedTime.

Created: fi.ModTime(),

})

}

// Sort bucket infos by bucket name.

sort.Sort(byBucketName(bucketInfos))

// Succes.

return bucketInfos, nil

}

// DeleteBucket - delete a bucket and all the metadata associated

// with the bucket including pending multipart, object metadata.

func (fs *FSObjects) DeleteBucket(ctx context.Context, bucket string) error {

bucketLock := fs.nsMutex.NewNSLock(bucket, "")

if err := bucketLock.GetLock(globalObjectTimeout); err != nil {

return err

}

defer bucketLock.Unlock()

bucketDir, err := fs.getBucketDir(bucket)

if err != nil {

return toObjectErr(err, bucket)

}

// Attempt to delete regular bucket.

if err = fsRemoveDir(bucketDir); err != nil {

return toObjectErr(err, bucket)

}

// Cleanup all the previously incomplete multiparts.

minioMetaMultipartBucketDir := pathJoin(fs.fsPath, minioMetaMultipartBucket, bucket)

if err = fsRemoveAll(minioMetaMultipartBucketDir); err != nil {

return toObjectErr(err, bucket)

}

// Cleanup all the bucket metadata.

minioMetadataBucketDir := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket)

if err = fsRemoveAll(minioMetadataBucketDir); err != nil {

return toObjectErr(err, bucket)

}

// Delete all bucket metadata.

deleteBucketMetadata(bucket, fs)

return nil

}

/// Object Operations

// CopyObject - copy object source object to destination object.

// if source object and destination object are same we only

// update metadata.

func (fs *FSObjects) CopyObject(ctx context.Context, srcBucket, srcObject, dstBucket, dstObject string, srcInfo ObjectInfo) (oi ObjectInfo, e error) {

cpSrcDstSame := isStringEqual(pathJoin(srcBucket, srcObject), pathJoin(dstBucket, dstObject))

// Hold write lock on destination since in both cases

// - if source and destination are same

// - if source and destination are different

// it is the sole mutating state.

objectDWLock := fs.nsMutex.NewNSLock(dstBucket, dstObject)

if err := objectDWLock.GetLock(globalObjectTimeout); err != nil {

return oi, err

}

defer objectDWLock.Unlock()

// if source and destination are different, we have to hold

// additional read lock as well to protect against writes on

// source.

if !cpSrcDstSame {

// Hold read locks on source object only if we are

// going to read data from source object.

objectSRLock := fs.nsMutex.NewNSLock(srcBucket, srcObject)

if err := objectSRLock.GetRLock(globalObjectTimeout); err != nil {

return oi, err

}

defer objectSRLock.RUnlock()

}

if _, err := fs.statBucketDir(srcBucket); err != nil {

return oi, toObjectErr(err, srcBucket)

}

if cpSrcDstSame && srcInfo.metadataOnly {

// Close any writer which was initialized.

defer srcInfo.Writer.Close()

fsMetaPath := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, srcBucket, srcObject, fsMetaJSONFile)

wlk, err := fs.rwPool.Write(fsMetaPath)

if err != nil {

return oi, toObjectErr(errors.Trace(err), srcBucket, srcObject)

}

// This close will allow for locks to be synchronized on `fs.json`.

defer wlk.Close()

// Save objects' metadata in `fs.json`.

fsMeta := newFSMetaV1()

if _, err = fsMeta.ReadFrom(wlk); err != nil {

return oi, toObjectErr(err, srcBucket, srcObject)

}

fsMeta.Meta = srcInfo.UserDefined

fsMeta.Meta["etag"] = srcInfo.ETag

if _, err = fsMeta.WriteTo(wlk); err != nil {

return oi, toObjectErr(err, srcBucket, srcObject)

}

// Stat the file to get file size.

fi, err := fsStatFile(pathJoin(fs.fsPath, srcBucket, srcObject))

if err != nil {

return oi, toObjectErr(err, srcBucket, srcObject)

}

// Return the new object info.

return fsMeta.ToObjectInfo(srcBucket, srcObject, fi), nil

}

go func() {

if gerr := fs.getObject(srcBucket, srcObject, 0, srcInfo.Size, srcInfo.Writer, srcInfo.ETag, !cpSrcDstSame); gerr != nil {

if gerr = srcInfo.Writer.Close(); gerr != nil {

errorIf(gerr, "Unable to read the object %s/%s.", srcBucket, srcObject)

}

return

}

// Close writer explicitly signalling we wrote all data.

if gerr := srcInfo.Writer.Close(); gerr != nil {

errorIf(gerr, "Unable to read the object %s/%s.", srcBucket, srcObject)

return

}

}()

objInfo, err := fs.putObject(dstBucket, dstObject, srcInfo.Reader, srcInfo.UserDefined)

if err != nil {

return oi, toObjectErr(err, dstBucket, dstObject)

}

return objInfo, nil

}

// GetObject - reads an object from the disk.

// Supports additional parameters like offset and length

// which are synonymous with HTTP Range requests.

//

// startOffset indicates the starting read location of the object.

// length indicates the total length of the object.

func (fs *FSObjects) GetObject(ctx context.Context, bucket, object string, offset int64, length int64, writer io.Writer, etag string) (err error) {

if err = checkGetObjArgs(bucket, object); err != nil {

return err

}

// Lock the object before reading.

objectLock := fs.nsMutex.NewNSLock(bucket, object)

if err := objectLock.GetRLock(globalObjectTimeout); err != nil {

return err

}

defer objectLock.RUnlock()

return fs.getObject(bucket, object, offset, length, writer, etag, true)

}

// getObject - wrapper for GetObject

func (fs *FSObjects) getObject(bucket, object string, offset int64, length int64, writer io.Writer, etag string, lock bool) (err error) {

if _, err = fs.statBucketDir(bucket); err != nil {

return toObjectErr(err, bucket)

}

// Offset cannot be negative.

if offset < 0 {

return toObjectErr(errors.Trace(errUnexpected), bucket, object)

}

// Writer cannot be nil.

if writer == nil {

return toObjectErr(errors.Trace(errUnexpected), bucket, object)

}

// If its a directory request, we return an empty body.

if hasSuffix(object, slashSeparator) {

_, err = writer.Write([]byte(""))

return toObjectErr(errors.Trace(err), bucket, object)

}

if bucket != minioMetaBucket {

fsMetaPath := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket, object, fsMetaJSONFile)

if lock {

_, err = fs.rwPool.Open(fsMetaPath)

if err != nil && err != errFileNotFound {

return toObjectErr(errors.Trace(err), bucket, object)

}

defer fs.rwPool.Close(fsMetaPath)

}

}

if etag != "" {

objEtag, perr := fs.getObjectETag(bucket, object, lock)

if perr != nil {

return toObjectErr(errors.Trace(perr), bucket, object)

}

if objEtag != etag {

return toObjectErr(errors.Trace(InvalidETag{}), bucket, object)

}

}

// Read the object, doesn't exist returns an s3 compatible error.

fsObjPath := pathJoin(fs.fsPath, bucket, object)

reader, size, err := fsOpenFile(fsObjPath, offset)

if err != nil {

return toObjectErr(err, bucket, object)

}

defer reader.Close()

bufSize := int64(readSizeV1)

if length > 0 && bufSize > length {

bufSize = length

}

// For negative length we read everything.

if length < 0 {

length = size - offset

}

// Reply back invalid range if the input offset and length fall out of range.

if offset > size || offset+length > size {

return errors.Trace(InvalidRange{offset, length, size})

}

// Allocate a staging buffer.

buf := make([]byte, int(bufSize))

_, err = io.CopyBuffer(writer, io.LimitReader(reader, length), buf)

return toObjectErr(errors.Trace(err), bucket, object)

}

// getObjectInfo - wrapper for reading object metadata and constructs ObjectInfo.

func (fs *FSObjects) getObjectInfo(bucket, object string) (oi ObjectInfo, e error) {

fsMeta := fsMetaV1{}

fi, err := fsStatDir(pathJoin(fs.fsPath, bucket, object))

if err != nil && errors.Cause(err) != errFileAccessDenied {

return oi, toObjectErr(err, bucket, object)

}

if fi != nil {

// If file found and request was with object ending with "/", consider it

// as directory and return object info

if hasSuffix(object, slashSeparator) {

return fsMeta.ToObjectInfo(bucket, object, fi), nil

}

return oi, toObjectErr(errFileNotFound, bucket, object)

}

fsMetaPath := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket, object, fsMetaJSONFile)

// Read `fs.json` to perhaps contend with

// parallel Put() operations.

rlk, err := fs.rwPool.Open(fsMetaPath)

if err == nil {

// Read from fs metadata only if it exists.

defer fs.rwPool.Close(fsMetaPath)

if _, rerr := fsMeta.ReadFrom(rlk.LockedFile); rerr != nil {

// `fs.json` can be empty due to previously failed

// PutObject() transaction, if we arrive at such

// a situation we just ignore and continue.

if errors.Cause(rerr) != io.EOF {

return oi, toObjectErr(rerr, bucket, object)

}

}

}

// Ignore if `fs.json` is not available, this is true for pre-existing data.

if err != nil && err != errFileNotFound {

return oi, toObjectErr(errors.Trace(err), bucket, object)

}

// Stat the file to get file size.

fi, err = fsStatFile(pathJoin(fs.fsPath, bucket, object))

if err != nil {

return oi, toObjectErr(err, bucket, object)

}

return fsMeta.ToObjectInfo(bucket, object, fi), nil

}

// GetObjectInfo - reads object metadata and replies back ObjectInfo.

func (fs *FSObjects) GetObjectInfo(ctx context.Context, bucket, object string) (oi ObjectInfo, e error) {

// Lock the object before reading.

objectLock := fs.nsMutex.NewNSLock(bucket, object)

if err := objectLock.GetRLock(globalObjectTimeout); err != nil {

return oi, err

}

defer objectLock.RUnlock()

if err := checkGetObjArgs(bucket, object); err != nil {

return oi, err

}

if _, err := fs.statBucketDir(bucket); err != nil {

return oi, toObjectErr(err, bucket)

}

return fs.getObjectInfo(bucket, object)

}

// This function does the following check, suppose

// object is "a/b/c/d", stat makes sure that objects ""a/b/c""

// "a/b" and "a" do not exist.

func (fs *FSObjects) parentDirIsObject(bucket, parent string) bool {

var isParentDirObject func(string) bool

isParentDirObject = func(p string) bool {

if p == "." || p == "/" {

return false

}

if _, err := fsStatFile(pathJoin(fs.fsPath, bucket, p)); err == nil {

// If there is already a file at prefix "p", return true.

return true

}

// Check if there is a file as one of the parent paths.

return isParentDirObject(path.Dir(p))

}

return isParentDirObject(parent)

}

// PutObject - creates an object upon reading from the input stream

// until EOF, writes data directly to configured filesystem path.

// Additionally writes `fs.json` which carries the necessary metadata

// for future object operations.

func (fs *FSObjects) PutObject(ctx context.Context, bucket string, object string, data *hash.Reader, metadata map[string]string) (objInfo ObjectInfo, retErr error) {

if err := checkPutObjectArgs(bucket, object, fs, data.Size()); err != nil {

return ObjectInfo{}, err

}

// Lock the object.

objectLock := fs.nsMutex.NewNSLock(bucket, object)

if err := objectLock.GetLock(globalObjectTimeout); err != nil {

return objInfo, err

}

defer objectLock.Unlock()

return fs.putObject(bucket, object, data, metadata)

}

// putObject - wrapper for PutObject

func (fs *FSObjects) putObject(bucket string, object string, data *hash.Reader, metadata map[string]string) (objInfo ObjectInfo, retErr error) {

// No metadata is set, allocate a new one.

if metadata == nil {

metadata = make(map[string]string)

}

var err error

// Validate if bucket name is valid and exists.

if _, err = fs.statBucketDir(bucket); err != nil {

return ObjectInfo{}, toObjectErr(err, bucket)

}

fsMeta := newFSMetaV1()

fsMeta.Meta = metadata

// This is a special case with size as '0' and object ends

// with a slash separator, we treat it like a valid operation

// and return success.

if isObjectDir(object, data.Size()) {

// Check if an object is present as one of the parent dir.

if fs.parentDirIsObject(bucket, path.Dir(object)) {

return ObjectInfo{}, toObjectErr(errors.Trace(errFileAccessDenied), bucket, object)

}

if err = mkdirAll(pathJoin(fs.fsPath, bucket, object), 0777); err != nil {

return ObjectInfo{}, toObjectErr(err, bucket, object)

}

var fi os.FileInfo

if fi, err = fsStatDir(pathJoin(fs.fsPath, bucket, object)); err != nil {

return ObjectInfo{}, toObjectErr(err, bucket, object)

}

return fsMeta.ToObjectInfo(bucket, object, fi), nil

}

if err = checkPutObjectArgs(bucket, object, fs, data.Size()); err != nil {

return ObjectInfo{}, err

}

// Check if an object is present as one of the parent dir.

if fs.parentDirIsObject(bucket, path.Dir(object)) {

return ObjectInfo{}, toObjectErr(errors.Trace(errFileAccessDenied), bucket, object)

}

// Validate input data size and it can never be less than zero.

if data.Size() < 0 {

return ObjectInfo{}, errors.Trace(errInvalidArgument)

}

var wlk *lock.LockedFile

if bucket != minioMetaBucket {

bucketMetaDir := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix)

fsMetaPath := pathJoin(bucketMetaDir, bucket, object, fsMetaJSONFile)

wlk, err = fs.rwPool.Create(fsMetaPath)

if err != nil {

return ObjectInfo{}, toObjectErr(errors.Trace(err), bucket, object)

}

// This close will allow for locks to be synchronized on `fs.json`.

defer wlk.Close()

defer func() {

// Remove meta file when PutObject encounters any error

if retErr != nil {

tmpDir := pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID)

fsRemoveMeta(bucketMetaDir, fsMetaPath, tmpDir)

}

}()

}

// Uploaded object will first be written to the temporary location which will eventually

// be renamed to the actual location. It is first written to the temporary location

// so that cleaning it up will be easy if the server goes down.

tempObj := mustGetUUID()

// Allocate a buffer to Read() from request body

bufSize := int64(readSizeV1)

if size := data.Size(); size > 0 && bufSize > size {

bufSize = size

}

buf := make([]byte, int(bufSize))

fsTmpObjPath := pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID, tempObj)

bytesWritten, err := fsCreateFile(fsTmpObjPath, data, buf, data.Size())

if err != nil {

fsRemoveFile(fsTmpObjPath)

return ObjectInfo{}, toObjectErr(err, bucket, object)

}

metadata["etag"] = hex.EncodeToString(data.MD5Current())

// Should return IncompleteBody{} error when reader has fewer

// bytes than specified in request header.

if bytesWritten < data.Size() {

fsRemoveFile(fsTmpObjPath)

return ObjectInfo{}, errors.Trace(IncompleteBody{})

}

// Delete the temporary object in the case of a

// failure. If PutObject succeeds, then there would be

// nothing to delete.

defer fsRemoveFile(fsTmpObjPath)

// Entire object was written to the temp location, now it's safe to rename it to the actual location.

fsNSObjPath := pathJoin(fs.fsPath, bucket, object)

if err = fsRenameFile(fsTmpObjPath, fsNSObjPath); err != nil {

return ObjectInfo{}, toObjectErr(err, bucket, object)

}

if bucket != minioMetaBucket {

// Write FS metadata after a successful namespace operation.

if _, err = fsMeta.WriteTo(wlk); err != nil {

return ObjectInfo{}, toObjectErr(err, bucket, object)

}

}

// Stat the file to fetch timestamp, size.

fi, err := fsStatFile(pathJoin(fs.fsPath, bucket, object))

if err != nil {

return ObjectInfo{}, toObjectErr(err, bucket, object)

}

// Success.

return fsMeta.ToObjectInfo(bucket, object, fi), nil

}

// DeleteObject - deletes an object from a bucket, this operation is destructive

// and there are no rollbacks supported.

func (fs *FSObjects) DeleteObject(ctx context.Context, bucket, object string) error {

// Acquire a write lock before deleting the object.

objectLock := fs.nsMutex.NewNSLock(bucket, object)

if err := objectLock.GetLock(globalOperationTimeout); err != nil {

return err

}

defer objectLock.Unlock()

if err := checkDelObjArgs(bucket, object); err != nil {

return err

}

if _, err := fs.statBucketDir(bucket); err != nil {

return toObjectErr(err, bucket)

}

minioMetaBucketDir := pathJoin(fs.fsPath, minioMetaBucket)

fsMetaPath := pathJoin(minioMetaBucketDir, bucketMetaPrefix, bucket, object, fsMetaJSONFile)

if bucket != minioMetaBucket {

rwlk, lerr := fs.rwPool.Write(fsMetaPath)

if lerr == nil {

// This close will allow for fs locks to be synchronized on `fs.json`.

defer rwlk.Close()

}

if lerr != nil && lerr != errFileNotFound {

return toObjectErr(errors.Trace(lerr), bucket, object)

}

}

// Delete the object.

if err := fsDeleteFile(pathJoin(fs.fsPath, bucket), pathJoin(fs.fsPath, bucket, object)); err != nil {

return toObjectErr(err, bucket, object)

}

if bucket != minioMetaBucket {

// Delete the metadata object.

err := fsDeleteFile(minioMetaBucketDir, fsMetaPath)

if err != nil && errors.Cause(err) != errFileNotFound {

return toObjectErr(err, bucket, object)

}

}

return nil

}

// Returns function "listDir" of the type listDirFunc.

// isLeaf - is used by listDir function to check if an entry

// is a leaf or non-leaf entry.

func (fs *FSObjects) listDirFactory(isLeaf isLeafFunc) listDirFunc {

// listDir - lists all the entries at a given prefix and given entry in the prefix.

listDir := func(bucket, prefixDir, prefixEntry string) (entries []string, delayIsLeaf bool, err error) {

entries, err = readDir(pathJoin(fs.fsPath, bucket, prefixDir))

if err != nil {

return nil, false, err

}

entries, delayIsLeaf = filterListEntries(bucket, prefixDir, entries, prefixEntry, isLeaf)

return entries, delayIsLeaf, nil

}

// Return list factory instance.

return listDir

}

// getObjectETag is a helper function, which returns only the md5sum

// of the file on the disk.

func (fs *FSObjects) getObjectETag(bucket, entry string, lock bool) (string, error) {

fsMetaPath := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket, entry, fsMetaJSONFile)

var reader io.Reader

var fi os.FileInfo

var size int64

if lock {

// Read `fs.json` to perhaps contend with

// parallel Put() operations.

rlk, err := fs.rwPool.Open(fsMetaPath)

// Ignore if `fs.json` is not available, this is true for pre-existing data.

if err != nil && err != errFileNotFound {

return "", toObjectErr(errors.Trace(err), bucket, entry)

}

// If file is not found, we don't need to proceed forward.

if err == errFileNotFound {

return "", nil

}

// Read from fs metadata only if it exists.

defer fs.rwPool.Close(fsMetaPath)

// Fetch the size of the underlying file.

fi, err = rlk.LockedFile.Stat()

if err != nil {

return "", toObjectErr(errors.Trace(err), bucket, entry)

}

size = fi.Size()

reader = io.NewSectionReader(rlk.LockedFile, 0, fi.Size())

} else {

var err error

reader, size, err = fsOpenFile(fsMetaPath, 0)

if err != nil {

return "", toObjectErr(errors.Trace(err), bucket, entry)

}

}

// `fs.json` can be empty due to previously failed

// PutObject() transaction, if we arrive at such

// a situation we just ignore and continue.

if size == 0 {

return "", nil

}

fsMetaBuf, err := ioutil.ReadAll(reader)

if err != nil {

return "", toObjectErr(errors.Trace(err), bucket, entry)

}

// Check if FS metadata is valid, if not return error.

if !isFSMetaValid(parseFSVersion(fsMetaBuf), parseFSFormat(fsMetaBuf)) {

return "", toObjectErr(errors.Trace(errCorruptedFormat), bucket, entry)

}

return extractETag(parseFSMetaMap(fsMetaBuf)), nil

}

// ListObjects - list all objects at prefix upto maxKeys., optionally delimited by '/'. Maintains the list pool

// state for future re-entrant list requests.

func (fs *FSObjects) ListObjects(ctx context.Context, bucket, prefix, marker, delimiter string, maxKeys int) (loi ListObjectsInfo, e error) {

if err := checkListObjsArgs(bucket, prefix, marker, delimiter, fs); err != nil {

return loi, err

}

// Marker is set validate pre-condition.

if marker != "" {

// Marker not common with prefix is not implemented.Send an empty response

if !hasPrefix(marker, prefix) {

return ListObjectsInfo{}, e

}

}

if _, err := fs.statBucketDir(bucket); err != nil {

return loi, err

}

// With max keys of zero we have reached eof, return right here.

if maxKeys == 0 {

return loi, nil

}

// For delimiter and prefix as '/' we do not list anything at all

// since according to s3 spec we stop at the 'delimiter'

// along // with the prefix. On a flat namespace with 'prefix'

// as '/' we don't have any entries, since all the keys are

// of form 'keyName/...'

if delimiter == slashSeparator && prefix == slashSeparator {

return loi, nil

}

// Over flowing count - reset to maxObjectList.

if maxKeys < 0 || maxKeys > maxObjectList {

maxKeys = maxObjectList

}

// Default is recursive, if delimiter is set then list non recursive.

recursive := true

if delimiter == slashSeparator {

recursive = false

}

// Convert entry to ObjectInfo

entryToObjectInfo := func(entry string) (objInfo ObjectInfo, err error) {

// Protect the entry from concurrent deletes, or renames.

objectLock := fs.nsMutex.NewNSLock(bucket, entry)

if err = objectLock.GetRLock(globalListingTimeout); err != nil {

return ObjectInfo{}, err

}

defer objectLock.RUnlock()

return fs.getObjectInfo(bucket, entry)

}

heal := false // true only for xl.ListObjectsHeal()

walkResultCh, endWalkCh := fs.listPool.Release(listParams{bucket, recursive, marker, prefix, heal})

if walkResultCh == nil {

endWalkCh = make(chan struct{})

isLeaf := func(bucket, object string) bool {

// bucket argument is unused as we don't need to StatFile

// to figure if it's a file, just need to check that the

// object string does not end with "/".

return !hasSuffix(object, slashSeparator)

}

listDir := fs.listDirFactory(isLeaf)

walkResultCh = startTreeWalk(bucket, prefix, marker, recursive, listDir, isLeaf, endWalkCh)

}

var objInfos []ObjectInfo

var eof bool

var nextMarker string

// List until maxKeys requested.

for i := 0; i < maxKeys; {

walkResult, ok := <-walkResultCh

if !ok {

// Closed channel.

eof = true

break

}

// For any walk error return right away.

if walkResult.err != nil {

// File not found is a valid case.

if errors.Cause(walkResult.err) == errFileNotFound {

return loi, nil

}

return loi, toObjectErr(walkResult.err, bucket, prefix)

}

objInfo, err := entryToObjectInfo(walkResult.entry)

if err != nil {

errorIf(err, "Unable to fetch object info for %s", walkResult.entry)

return loi, nil

}

nextMarker = objInfo.Name

objInfos = append(objInfos, objInfo)

if walkResult.end {

eof = true

break

}

i++

}

// Save list routine for the next marker if we haven't reached EOF.

params := listParams{bucket, recursive, nextMarker, prefix, heal}

if !eof {

fs.listPool.Set(params, walkResultCh, endWalkCh)

}