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From Joe Orton <jor...@redhat.com>
Subject Re: Time for 2.2.4?
Date Thu, 09 Nov 2006 22:12:23 GMT
On Thu, Nov 09, 2006 at 06:18:17PM +0100, Mladen Turk wrote:
> Joe Orton wrote:
> >
> >2) it's a really bad implementation.  You can do the same thing portably 
> >by doing a poll() and a recv(,MSG_PEEK) AFAICT.  There is no need to 
> >muck about with ioctls, and it can be done already without adding 
> >anything to APR.
> 
> recv(, MSG_PEEK) is not portable

It's certainly *more* portable; it should work on any POSIX system 
unlike the ioctl.  Have you tested it on Win32?  With APR you'd have to 
use apr_socket_recvfrom to be able to pass a flags argument, annoyingly.

>, so its not APR only anyhow.
> Further more the poll resolution is millisecond.

A zero-timeout poll or select is sufficient to determine readability 
without blocking.  Actually if you use a non-blocking socket the 
poll/select should be unnecessary if using recv/MSG_PEEK anyway, it 
doesn't tell you anything extra.

recv/MSG_PEEK == 0 => EOF => not ESTABLISHED
recv/MSG_PEEK < 0 && !EWOULDBLOCKy(rv) => socket error, not ESTABLISHED
recv/MSG_PEEK < 0 && EWOULDBLOCKy(rv) => empty recv buffer, ESTABLISHED

> >2. b) using select() like that will SIGSEGV on Unix for an fd > 
> >FD_SETSIZE.  There is no excuse to at least not use apr_poll()
> 
> Hmm. select(1, ...) can probably be used instead select((int)sock + 1, ...)

It's the FD_SET call which has undefined behaviour for an fd >= 
FD_SETSIZE.  Calling select(1, ... on Unix will make select act like 
sleep() unless you have an fd == 0 entry in the fdset.

Regards,

joe

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