On 5/27/10, Erik Faye-Lund <kusmabite@xxxxxxxxxxxxxx> wrote:
> On Thu, May 27, 2010 at 3:58 PM, Marko Kreen <markokr@xxxxxxxxx> wrote:
> > On 5/27/10, Erik Faye-Lund <kusmabite@xxxxxxxxxxxxxx> wrote:
> >> On Thu, May 27, 2010 at 3:29 PM, Marko Kreen <markokr@xxxxxxxxx> wrote:
> >> > On 5/27/10, Erik Faye-Lund <kusmabite@xxxxxxxxxxxxxx> wrote:
> >> >> On Thu, May 27, 2010 at 1:00 PM, Erik Faye-Lund
> >> >> <kusmabite@xxxxxxxxxxxxxx> wrote:
> >> >> > On Thu, May 27, 2010 at 12:10 PM, Jonathan Nieder <jrnieder@xxxxxxxxx> 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 :)
> >> >
> >> > Well, per your own FD_SET example, the FD_SETSIZE on windows
> >> > means different thing than FD_SETSIZE on old-style bitmap-based
> >> > select() implementation.
> >> >
> >> > On Unix, it's max fd number + 1, on windows it's max count.
> >> >
> >>
> >>
> >> Are you sure this applies for all Unix, not just some given Unix-y system?
> >
> > Not sure. Just pointing out that the above check is not
> > universal enough.
> >
>
>
> Isn't it? How could one possibly pass more than max fd number + 1 file
> descriptors, since they start at 0? I guess one could specify a given
> fd more than once, but that'd be kind of redundant... and also very
> unlikely in our case ;)
Pass one fd with value 70 it. Check returns error, although
everything would work.
--
marko
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