Re: [Xen-devel] [PATCH XEN v2 08/15] tools: Refactor /dev/xen/gnt{dev, shr} wrappers into libxengnttab.

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 22/09/15 12:25, Ian Campbell wrote:
> Any thoughts/preferences on this library interface regarding:
>
> The use of a (perhaps to be added) grant_ref_t in preference to uint32_t as
> it is now?
Probably a good idea.  We should also introduce/use domid_t consistently 
through the new API as well.
> The use of bool rather than int for "writeable"?
Depends if we go for -std=c89 or -std=c99.

Given that it is 2015, I vote for -std=c99 and all the niceties it 
brings, such as bool.
> Mapping functions returning NULL on failure (rather than e.g MAP_FAILED)?
> (current code squashes any underlying MAP_FAILED into NULL, but of course
> that prevents mapping things at NULL, but then I'm not sure why we would
> want to support that).
+1

Anyone code choosing to try and map a grant ref at 0 can handcode the 
systemcalls itself.  Sane software will be much happier with NULL as the 
failure check.
~Andrew

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