backends: make NewObject return fs.ErrorIsDir if possible

This changes the interface to NewObject so that if NewObject is called
on a directory then it should return fs.ErrorIsDir if possible without
doing any extra work, otherwise fs.ErrorObjectNotFound.

Tested on integration test server with:

go run integration-test.go -tests backend -run TestIntegration/FsMkdir/FsPutFiles/FsNewObjectDir -branch fix-stat -maxtries 1

backend/box/box.go

@@ -1184,6 +1184,9 @@ func (o *Object) Size() int64 {
 
 // setMetaData sets the metadata from info
 func (o *Object) setMetaData(info *api.Item) (err error) {
+	if info.Type == api.ItemTypeFolder {
+		return fs.ErrorIsDir
+	}
 	if info.Type != api.ItemTypeFile {
 		return errors.Wrapf(fs.ErrorNotAFile, "%q is %q", o.remote, info.Type)
 	}

backend/drive/drive.go

@@ -1374,7 +1374,7 @@ func (f *Fs) newObjectWithExportInfo(
 	}
 	switch {
 	case info.MimeType == driveFolderType:
-		return nil, fs.ErrorNotAFile
+		return nil, fs.ErrorIsDir
 	case info.MimeType == shortcutMimeType:
 		// We can only get here if f.opt.SkipShortcuts is set
 		// and not from a listing. This is unlikely.
@@ -2922,7 +2922,7 @@ func (f *Fs) makeShortcut(ctx context.Context, srcPath string, dstFs *Fs, dstPat
 		}
 		isDir = true
 	} else if srcObj, err := srcFs.NewObject(ctx, srcPath); err != nil {
-		if err != fs.ErrorNotAFile {
+		if err != fs.ErrorIsDir {
 			return nil, errors.Wrap(err, "can't find source")
 		}
 		// source was a directory
@@ -2942,7 +2942,7 @@ func (f *Fs) makeShortcut(ctx context.Context, srcPath string, dstFs *Fs, dstPat
 	if err != fs.ErrorObjectNotFound {
 		if err == nil {
 			err = errors.New("existing file")
-		} else if err == fs.ErrorNotAFile {
+		} else if err == fs.ErrorIsDir {
 			err = errors.New("existing directory")
 		}
 		return nil, errors.Wrap(err, "not overwriting shortcut target")

backend/dropbox/dropbox.go

@@ -624,6 +624,9 @@ func (f *Fs) getFileMetadata(ctx context.Context, filePath string) (fileInfo *fi
 	}
 	fileInfo, ok := entry.(*files.FileMetadata)
 	if !ok {
+		if _, ok = entry.(*files.FolderMetadata); ok {
+			return nil, fs.ErrorIsDir
+		}
 		return nil, fs.ErrorNotAFile
 	}
 	return fileInfo, nil

backend/filefabric/filefabric.go

@@ -1089,7 +1089,7 @@ func (o *Object) Size() int64 {
 // setMetaData sets the metadata from info
 func (o *Object) setMetaData(info *api.Item) (err error) {
 	if info.Type != api.ItemTypeFile {
-		return errors.Wrapf(fs.ErrorNotAFile, "%q is %q", o.remote, info.Type)
+		return fs.ErrorIsDir
 	}
 	o.hasMetaData = true
 	o.size = info.Size

backend/jottacloud/jottacloud.go

@@ -599,7 +599,9 @@ func (f *Fs) readMetaDataForPath(ctx context.Context, path string) (info *api.Jo
 	if err != nil {
 		return nil, errors.Wrap(err, "read metadata failed")
 	}
-	if result.XMLName.Local != "file" {
+	if result.XMLName.Local == "folder" {
+		return nil, fs.ErrorIsDir
+	} else if result.XMLName.Local != "file" {
 		return nil, fs.ErrorNotAFile
 	}
 	return &result, nil
@@ -762,7 +764,7 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	// Renew the token in the background
 	f.tokenRenewer = oauthutil.NewRenew(f.String(), ts, func() error {
 		_, err := f.readMetaDataForPath(ctx, "")
-		if err == fs.ErrorNotAFile {
+		if err == fs.ErrorNotAFile || err == fs.ErrorIsDir {
 			err = nil
 		}
 		return err
@@ -784,7 +786,7 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 		}
 		_, err := f.NewObject(context.TODO(), remote)
 		if err != nil {
-			if errors.Cause(err) == fs.ErrorObjectNotFound || errors.Cause(err) == fs.ErrorNotAFile {
+			if uErr := errors.Cause(err); uErr == fs.ErrorObjectNotFound || uErr == fs.ErrorNotAFile || uErr == fs.ErrorIsDir {
 				// File doesn't exist so return old f
 				f.root = root
 				return f, nil

backend/koofr/koofr.go

@@ -344,7 +344,7 @@ func (f *Fs) NewObject(ctx context.Context, remote string) (obj fs.Object, err e
 		return nil, translateErrorsObject(err)
 	}
 	if info.Type == "dir" {
-		return nil, fs.ErrorNotAFile
+		return nil, fs.ErrorIsDir
 	}
 	return &Object{
 		fs:     f,

backend/local/local.go

@@ -401,7 +401,7 @@ func (f *Fs) newObjectWithInfo(remote string, info os.FileInfo) (fs.Object, erro
 
 	}
 	if o.mode.IsDir() {
-		return nil, errors.Wrapf(fs.ErrorNotAFile, "%q", remote)
+		return nil, fs.ErrorIsDir
 	}
 	return o, nil
 }

backend/mailru/mailru.go

@@ -1958,7 +1958,7 @@ func (o *Object) readMetaData(ctx context.Context, force bool) error {
 	}
 	newObj, ok := entry.(*Object)
 	if !ok || dirSize >= 0 {
-		return fs.ErrorNotAFile
+		return fs.ErrorIsDir
 	}
 	if newObj.remote != o.remote {
 		return fmt.Errorf("File %q path has changed to %q", o.remote, newObj.remote)

backend/mega/mega.go

@@ -303,7 +303,7 @@ func (f *Fs) findObject(rootNode *mega.Node, file string) (node *mega.Node, err
 	if err == mega.ENOENT {
 		return nil, fs.ErrorObjectNotFound
 	} else if err == nil && node.GetType() != mega.FILE {
-		return nil, fs.ErrorNotAFile
+		return nil, fs.ErrorIsDir // all other node types are directories
 	}
 	return node, err
 }
@@ -958,7 +958,7 @@ func (o *Object) Size() int64 {
 // setMetaData sets the metadata from info
 func (o *Object) setMetaData(info *mega.Node) (err error) {
 	if info.GetType() != mega.FILE {
-		return fs.ErrorNotAFile
+		return fs.ErrorIsDir // all other node types are directories
 	}
 	o.info = info
 	return nil

backend/onedrive/onedrive.go

@@ -1715,7 +1715,7 @@ func (o *Object) Size() int64 {
 // setMetaData sets the metadata from info
 func (o *Object) setMetaData(info *api.Item) (err error) {
 	if info.GetFolder() != nil {
-		return errors.Wrapf(fs.ErrorNotAFile, "%q", o.remote)
+		return fs.ErrorIsDir
 	}
 	o.hasMetaData = true
 	o.size = info.GetSize()

backend/putio/object.go

@@ -151,7 +151,7 @@ func (o *Object) readEntry(ctx context.Context) (f *putio.File, err error) {
 		return nil, err
 	}
 	if resp.File.IsDir() {
-		return nil, fs.ErrorNotAFile
+		return nil, fs.ErrorIsDir
 	}
 	return &resp.File, err
 }

backend/sftp/sftp.go

@@ -1383,7 +1383,7 @@ func (o *Object) stat(ctx context.Context) error {
 		return errors.Wrap(err, "stat failed")
 	}
 	if info.IsDir() {
-		return errors.Wrapf(fs.ErrorNotAFile, "%q", o.remote)
+		return fs.ErrorIsDir
 	}
 	o.setMetadata(info)
 	return nil

backend/sharefile/sharefile.go

@@ -337,8 +337,12 @@ func (f *Fs) readMetaDataForIDPath(ctx context.Context, id, path string, directo
 	if directoriesOnly && item.Type != api.ItemTypeFolder {
 		return nil, fs.ErrorIsFile
 	}
-	if filesOnly && item.Type != api.ItemTypeFile {
+	if filesOnly {
-		return nil, fs.ErrorNotAFile
+		if item.Type == api.ItemTypeFolder {
+			return nil, fs.ErrorIsDir
+		} else if item.Type != api.ItemTypeFile {
+			return nil, fs.ErrorNotAFile
+		}
 	}
 	return &item, nil
 }

backend/webdav/webdav.go

@@ -317,7 +317,7 @@ func (f *Fs) readMetaDataForPath(ctx context.Context, path string, depth string)
 		return nil, fs.ErrorObjectNotFound
 	}
 	if itemIsDir(&item) {
-		return nil, fs.ErrorNotAFile
+		return nil, fs.ErrorIsDir
 	}
 	return &item.Props, nil
 }
@@ -469,7 +469,7 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 		}
 		_, err := f.NewObject(ctx, remote)
 		if err != nil {
-			if errors.Cause(err) == fs.ErrorObjectNotFound || errors.Cause(err) == fs.ErrorNotAFile {
+			if errors.Cause(err) == fs.ErrorObjectNotFound || errors.Cause(err) == fs.ErrorIsDir {
 				// File doesn't exist so return old f
 				f.root = root
 				return f, nil

backend/yandex/yandex.go

@@ -949,7 +949,9 @@ func (o *Object) readMetaData(ctx context.Context) (err error) {
 	if err != nil {
 		return err
 	}
-	if info.ResourceType != "file" {
+	if info.ResourceType == "dir" {
+		return fs.ErrorIsDir
+	} else if info.ResourceType != "file" {
 		return fs.ErrorNotAFile
 	}
 	return o.setMetaData(info)

backend/zoho/zoho.go

@@ -1121,7 +1121,7 @@ func (o *Object) Size() int64 {
 // setMetaData sets the metadata from info
 func (o *Object) setMetaData(info *api.Item) (err error) {
 	if info.Attributes.IsFolder {
-		return fs.ErrorNotAFile
+		return fs.ErrorIsDir
 	}
 	o.hasMetaData = true
 	o.size = info.Attributes.StorageInfo.Size

fs/fs.go

@@ -37,6 +37,7 @@ var (
 	ErrorListAborted                 = errors.New("list aborted")
 	ErrorListBucketRequired          = errors.New("bucket or container name is needed in remote")
 	ErrorIsFile                      = errors.New("is a file not a directory")
+	ErrorIsDir                       = errors.New("is a directory not a file")
 	ErrorNotAFile                    = errors.New("is not a regular file")
 	ErrorNotDeleting                 = errors.New("not deleting files as there were IO errors")
 	ErrorNotDeletingDirs             = errors.New("not deleting directories as there were IO errors")

fs/types.go

@@ -28,6 +28,10 @@ type Fs interface {
 
 	// NewObject finds the Object at remote.  If it can't be found
 	// it returns the error ErrorObjectNotFound.
+	//
+	// If remote points to a directory then it should return
+	// ErrorIsDir if possible without doing any extra work,
+	// otherwise ErrorObjectNotFound.
 	NewObject(ctx context.Context, remote string) (Object, error)
 
 	// Put in to the remote path with the modTime given of the given size

fstest/fstests/fstests.go

@@ -1044,13 +1044,13 @@ func Run(t *testing.T, opt *Opt) {
 				fstest.CheckListing(t, f, []fstest.Item{file1, file2})
 			})
 
-			// TestFsNewObjectDir tests NewObject on a directory which should produce an error
+			// TestFsNewObjectDir tests NewObject on a directory which should produce fs.ErrorIsDir if possible or fs.ErrorObjectNotFound if not
 			t.Run("FsNewObjectDir", func(t *testing.T) {
 				skipIfNotOk(t)
 				dir := path.Dir(file2.Path)
 				obj, err := f.NewObject(ctx, dir)
 				assert.Nil(t, obj)
-				assert.NotNil(t, err)
+				assert.True(t, err == fs.ErrorIsDir || err == fs.ErrorObjectNotFound, fmt.Sprintf("Wrong error: expecting fs.ErrorIsDir or fs.ErrorObjectNotFound but got: %#v", err))
 			})
 
 			// TestFsPurge tests Purge