From: Gustavo A. R. Silva
> Sent: 25 March 2021 21:12
>
> On 3/25/21 10:29, David Laight wrote:
>
> >>>
> >>> Could you use the simpler:
> >>>> struct nfs_fhbase_new {
> >>>> __u8 fb_version;
> >>>> __u8 fb_auth_type;
> >>>> __u8 fb_fsid_type;
> >>>> __u8 fb_fileid_type;
> >>>> union {
> >>>> __u32 fb_auth[1];
> >>>> __u32 fb_auth_flex[0];
> >>>> };
> >>>> };
> >>>
> >>> Although I'm not certain flexible arrays are supported
> >>> as the last element of a union.
> >>
> >> Nope; this is not allowed: https://godbolt.org/z/14vd4o8na
> >
> > Nothing an extra 'struct {__u32 fb_auth_flex[0]; }'; won't solve.
>
> We don't want to introduce zero-length arrays [1].
I probably meant to write [] not [0] - doesn't affect the idea.
The real problem is that the compiler is likely to start rejecting
references to a flex array that go beyond the end of the outer
structure.
Thinking back, isn't fb_auth[] at least one entry long?
So it could be:
struct nfs_fhbase_new {
__u8 fb_version;
__u8 fb_auth_type;
__u8 fb_fsid_type;
__u8 fb_fileid_type;
__u32 fb_auth[1];
__u32 fb_auth_extra[];
};
(I've missed the 0 out this time...)
David
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