raiseFileDescriptorLimit

pub fn raiseFileDescriptorLimit() void {
    const have_rlimit = posix.rlimit_resource != void;
    if (!have_rlimit) return;

    var lim = posix.getrlimit(.NOFILE) catch return; // Oh well; we tried.
    if (native_os.isDarwin()) {
        // On Darwin, `NOFILE` is bounded by a hardcoded value `OPEN_MAX`.
        // According to the man pages for setrlimit():
        //   setrlimit() now returns with errno set to EINVAL in places that historically succeeded.
        //   It no longer accepts "rlim_cur = RLIM.INFINITY" for RLIM.NOFILE.
        //   Use "rlim_cur = min(OPEN_MAX, rlim_max)".
        lim.max = @min(std.c.OPEN_MAX, lim.max);
    }
    if (lim.cur == lim.max) return;

    // Do a binary search for the limit.
    var min: posix.rlim_t = lim.cur;
    var max: posix.rlim_t = 1 << 20;
    // But if there's a defined upper bound, don't search, just set it.
    if (lim.max != posix.RLIM.INFINITY) {
        min = lim.max;
        max = lim.max;
    }

    while (true) {
        lim.cur = min + @divTrunc(max - min, 2); // on freebsd rlim_t is signed
        if (posix.setrlimit(.NOFILE, lim)) |_| {
            min = lim.cur;
        } else |_| {
            max = lim.cur;
        }
        if (min + 1 >= max) break;
    }
}