Re: Return type of getrandom(2)

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On Oct 8, 2016 4:17 PM, "Theodore Ts'o" <tytso@xxxxxxx> wrote:
>
> On Sat, Oct 08, 2016 at 02:28:27PM +0200, Florian Weimer wrote:
> > The manual page says the return type of getrandom(2) is int, but
> > ssize_t would be more natural (see read(2) for comparison).  The
> > kernel uses ssize_t internally, which is converted to long on the
> > system call boundary.
> >
> > The difference does not currently matter because the return value is
> > limited to much less than INT_MAX in the implementation.
> >
> > Should we use int or ssize_t in the glibc system call wrapper?

I think it should be ssize_t.  Having the types mismatched across the
syscall boundary is just confusing.

(b) the maximum number of bytes returned will *always* be well
> under INT_MAX.

I would argue that this particular ship sailed when the len parameter
was given the type size_t.  The door is open for requests bigger than
2GiB.  Even if Linux will never honor those requests, I see no reason
to make their return value have a nonsensical type.

--Andy
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