Function hdfsGetDelegationToken 

pub unsafe extern "C" fn hdfsGetDelegationToken(
    fs: hdfsFS,
    renewer: *const c_char,
) -> *mut c_char

Get a delegation token from namenode. The token should be freed using hdfsFreeDelegationToken after canceling the token or token expired.

@param fs The file system @param renewer The user who will renew the token

@return Return a delegation token, NULL on error.