Re: recvmsg() "short receive" after FIONREAD

From: Andriy Gapon <>
Date: Sat, 11 Sep 2021 08:15:12 UTC
On 10/09/2021 22:40, Andriy Gapon wrote:
> On 10/09/2021 22:38, Andriy Gapon wrote:
>> On 10/09/2021 22:35, Mark Johnston wrote:
>>> Indeed, I suspect that this is the problem.  Note that for
>>> kevent(EVFILT_READ) we subtract the number of control message bytes from
>>> the returned value, see filt_soread().  I wonder if FIONREAD should do
>>> the same thing.
>> Thank you for the suggestion.
>> I think that it is a reasonable expectation that FIONREAD returns a number of 
>> bytes that can be actually read.
>> I'll look at filt_soread().
> kn_data = sbavail(&so->so_rcv) - so->so_rcv.sb_ctl;
> Is this it?
> Looks simple enough for a quick test :)

Works perfectly.
Should I just commit it or is a larger discussion needed?

Andriy Gapon