mount, cmount: don't pass huge filenames (>4k) to FUSE as it can't cope

cmd/cmount/fs.go

@@ -246,7 +246,12 @@ func (fsys *FS) Readdir(dirPath string,
 	for _, item := range items {
 		node, ok := item.(vfs.Node)
 		if ok {
-			fill(node.Name(), nil, 0)
+			name := node.Name()
+			if len(name) > mountlib.MaxLeafSize {
+				fs.Errorf(dirPath, "Name too long (%d bytes) for FUSE, skipping: %s", len(name), name)
+				continue
+			}
+			fill(name, nil, 0)
 		}
 	}
 	itemsRead = len(items)

cmd/mount/dir.go

@@ -11,6 +11,7 @@ import (
 	fusefs "bazil.org/fuse/fs"
 	"github.com/pkg/errors"
 	"github.com/rclone/rclone/cmd/mountlib"
+	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/log"
 	"github.com/rclone/rclone/vfs"
 )
@@ -96,10 +97,15 @@ func (d *Dir) ReadDirAll(ctx context.Context) (dirents []fuse.Dirent, err error)
 		return nil, translateError(err)
 	}
 	for _, node := range items {
+		name := node.Name()
+		if len(name) >= mountlib.MaxLeafSize {
+			fs.Errorf(d, "Name too long (%d bytes) for FUSE, skipping: %s", len(name), name)
+			continue
+		}
 		var dirent = fuse.Dirent{
 			// Inode FIXME ???
 			Type: fuse.DT_File,
-			Name: node.Name(),
+			Name: name,
 		}
 		if node.IsDir() {
 			dirent.Type = fuse.DT_Dir

cmd/mountlib/mount.go

@@ -38,6 +38,11 @@ var (
 	DaemonTimeout      time.Duration // OSXFUSE only
 )
 
+// Global constants
+const (
+	MaxLeafSize = 4095 // don't pass file names longer than this
+)
+
 func init() {
 	// DaemonTimeout defaults to non zero for macOS
 	if runtime.GOOS == "darwin" {