In article <2C639E24-25C7-4083-B000-973CC36DD05C@shagadelic.org>,
Jason Thorpe  <thorpej@shagadelic.org> wrote:
>
>On Jun 6, 2006, at 10:29 AM, Garrett D'Amore wrote:
>
>> That's not a bad idea.  Is there an example for passing properties in
>> ioctls, or is there another way to exchange this data?
>
>proplib is new enough that it's not being used for this purpose yet.   
>However, it's perfect for the "capabilities supported" / "options  
>enabled" kind of thing, where the list might grow in the future  
>(beyond 32-bits worth of features, perhaps).
>
>As for how to pass it back and forth, prop_dictionary_externalize()  
>before sending it across the boundary, prop_dictionary_internalize()  
>when receiving it from across the boundary.  Maybe we should even  
>make a generic ioctl argument:
>
>struct plistref {
>	const char *plist_ptr;
>	size_t plist_len;
>};
>
>Then your hypothetical "get capabilities" ioctl could be:
>
>#define	FOOGETCAPS	_IOWR('f', 0, struct plistref)
>
>and your "get properties" / "set properties" could be:
>
>#define	FOOSETPROPS	_IOW('f', 1, struct plistref)
>#define	FOOGETPROPS	_IOWR('f', 2, struct plistref)
>
>We could probably even have a generic helper function in the kernel,  
>and a corresponding one in userspace, that took care of the temporary  
>buffer allocation, etc.
>

shouldn't the pointer be const void *?

christos