On Wed, 26 Sep 2007 11:18:39 +0800 Herbert Xu <[EMAIL PROTECTED]> wrote:
> Stephen Hemminger <[EMAIL PROTECTED]> wrote: > > The bug http://bugzilla.kernel.org/show_bug.cgi?id=5731 > > describes an issue where write() can't be used to generate a zero-length > > datagram (but send, and sendto do work). > > > > I think the following is needed: > > > > --- a/net/socket.c 2007-08-20 09:54:28.000000000 -0700 > > +++ b/net/socket.c 2007-09-24 15:31:25.000000000 -0700 > > @@ -777,8 +777,11 @@ static ssize_t sock_aio_write(struct kio > > if (pos != 0) > > return -ESPIPE; > > > > - if (iocb->ki_left == 0) /* Match SYS5 behaviour */ > > - return 0; > > + if (unlikely(iocb->ki_left == 0)) { > > + struct socket *sock = iocb->ki_filp->private_data; > > + if (sock->type == SOCK_STREAM) > > + return 0; > > + } > > I'm not sure whether all STREAM protocols treat zero-length > sends as no-ops. What about SCTP? > > Put it another way, do we really need to keep the short-circuit > for SOCK_STREAM? > > Cheers, Stream is defined as sequence of bytes. So short circuit makes sense If the application wants message boundaries it needs to use SOCK_SEQPACKET. I was paranoid about possible breakage in TCP or SCTP. But since send(s, buf, 0, 0) already filters through, I guess it doesn't matter. -- Stephen Hemminger <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
