Pass user data to HelperTool with BetterAuthorizationSampleLib(BAS) in Mac OS X?

I found that there is "use开发者_StackOverflow社区rData" filed in BASCommandSpec in BAS library:

struct BASCommandSpec {
    const char *    commandName;
    const char *    rightName;
    const char *    rightDefaultRule;
    const char *    rightDescriptionKey;
    const void *    userData;
};
typedef struct BASCommandSpec BASCommandSpec;

But I haven't found a way to use it. Does anybody know whether that is a useful field or just "reserved"? The documentation says that this can hold any value because BAS doesn't use it.

Is there is any other easy-to-use authorization lib/sample in C?