void *silc_sftp_fs_memory_alloc(SilcSFTPFSMemoryPerm perm);

    Allocates memory filesystem context and returns the context.  The
    context can be given as argument to the silc_sftp_server_start
    function. The context must be freed by the caller using the function
    silc_sftp_fs_memory_free. The `perm' is the permissions for the root
    directory of the filesystem (/ dir).