Async read an output stream but how many bytes ?

[Basile B. via Digitalmars-d-learn]

On Thursday, 31 March 2016 at 01:12:50 UTC, Adam D. Ruppe wrote:
> On Thursday, 31 March 2016 at 00:50:16 UTC, Basile B. wrote:
>> There should be a way to know how many bytes are available ?
>
> You are already using poll()... I'd just use read() directly on 
> the file number too. It will read as much as is available up to 
> the max size of the buffer, but if it can't fill it all, it 
> just does what it can and returns.

It's probably the only way. I've also tried 
core.stdc.stdio.readf() in a loop and it was also reading until 
the process termination. So I'll go for a single readf operation 
on a ubyte[].