Re: [PATCH] compat: Add another rudimentary poll() emulation

From: Erik Faye-Lund <kusmabite@googlemail.com>
Date: May 27, 2010, 13:06 UTC
Message-ID: <AANLkTikezlVaX8ARkRw8kEk9wL9RL_5I6X3vK83nzFUl@mail.gmail.com>
In-Reply-To: <AANLkTikYa2vq4PrKrO2QIkHVxYqbhUZRw42kQq875FNT@mail.gmail.com>

On Thu, May 27, 2010 at 1:00 PM, Erik Faye-Lund <kusmabite@googlemail.com> wrote:

Show 16 quoted lines

> On Thu, May 27, 2010 at 12:10 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:
>> Implement the subset of poll() semantics needed by git in terms of
>> select(), for use by the Interix port.  Inspired by commit 6ed807f
>> (Windows: A rudimentary poll() emulation, 2007-12-01).
>>
>
> A possible problem with this approach is that the maximum number of
> file descriptors poll can handle limited by RLIMIT_NOFILE, whereas the
> maximum number of file descriptors select can handle is limited by
> FD_SETSIZE.
>
> I don't think this is a big problem in reality, though - both values
> seem to be pretty high in most implementations. And IIRC git-daemon is
> the only one who needs more than 2, and it doesn't even check
> RLIMIT_NOFILE.
>

To be clear: I think this strategy is the best option (at least for non-Windows, where select() might be our only option).

But perhaps you should include a check along the lines of this:

if (nfds > FD_SETSIZE)
	return errno = EINVAL, error("poll: nfds must be below %d", FD_SETSIZE);

Just so we can know when the code fails :)

-- 
Erik "kusma" Faye-Lund