Async read an output stream but how many bytes ?

[Basile B. via Digitalmars-d-learn]

On Thursday, 31 March 2016 at 13:48:46 UTC, Steven Schveighoffer 
wrote:
> stdio.readf is buffered. It does not deal with async io 
> properly I think.
>
> -Steve

Yes, I must use core.sys.posix.unistd.read, which was actually 
what A.D.Ruppe suggested, I think.