Create write only site role

[guiguik]

Hi guys, I'm actually trying to create a custom role to give external user only upload rights.

I want that the guys could connect to alfresco share and get inside the documentlibrary, but I don't want him to be  able to see any subfolders. He must have only the upload button active to upload a document but he doesn't have right to navigate in my document library structure.

Can anybody could help me to achieve that.

I begin to create a custom permissionGroup but I don't know wich permission it should have.

      <permissionGroup name="SiteExternal" allowFullControl="false" expose="true">
          <includePermissionGroup permissionGroup="WriteContent" type="sys:base" />
      </permissionGroup>

Regards

[guiguik]

Just to say that I want only hidden a folder (user can't see it). It's a temporary folder where content are upload before being dispatch in my different folder.
I create a role with following permission:  

  
<permissionGroup name="WriteOnly" allowFullControl="false"
      expose="true">
      <includePermissionGroup permissionGroup="Write"
        type="sys:base" />
      <includePermissionGroup permissionGroup="AddChildren"
        type="sys:base" />
    </permissionGroup>
 ‍‍‍‍‍‍‍‍‍

and assign it to my folder. The folder is hidden but when I try to upload inside I have an error in share (Upload failure) but no error in Alfresco console.

What am I doing wrong?