non-block reading from pipe stdout

[Oleg B via Digitalmars-d-learn]

Hello. I run program through std.process.pipeShell and want to 
read from it stdout in loop. How do this non-blocking?

I try
        int fd = p.stdout.fileno;
        int flags = fcntl(fd, F_GETFL, 0);
        flags |= O_NONBLOCK;
        fcntl(fd, F_SETFL, flags);

but get error "Resource temporarily unavailable".