[MemMapFs] Will MemMapFs support creating read-only files?

[kizuna-lek]

When conducting tests, there are times when I want to create a read-only file,
But i found that there is no option available to create a read-only file.
I know there is ReadOnlyFs already, but new a fs seems unnecessary to me.

I found func Create in memmap.go

func (m *MemMapFs) Create(name string) (File, error) {
	name = normalizePath(name)
	m.mu.Lock()
	file := mem.CreateFile(name)
	m.getData()[name] = file
	m.registerWithParent(file, 0)
	m.mu.Unlock()
	return mem.NewFileHandle(file), nil
}

and NewReadOnlyFileHandle in file.go

func NewReadOnlyFileHandle(data *FileData) *File {
	return &File{fileData: data, readOnly: true}
}

Will it possible to support create read-only file with adding an additional parameter to the Create function like

func (m *MemMapFs) Create(name string, readOnly bool) (File, error) 
......
if readOnly {
    return NewReadOnlyFileHandle(file), nil
}
......

Or there might already be a way to create a read-only file.
I have tried func (m *MemMapFs) Chmod, but it seems useless.
If there are any better methods, i would appreciate to learn it.