Date: Sat, 15 Dec 2001 15:10:25 -0600 From: Alfred Perlstein <alfred@FreeBSD.org> To: Bruce Evans <bde@zeta.org.au> Cc: wollman@freebsd.org, net@freebsd.org, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: fifo fix (Re: cvs commit: src/sys/fs/fifofs fifo_vnops.c) Message-ID: <20011215151025.A82439@elvis.mu.org> In-Reply-To: <20011213120830.E79896@elvis.mu.org>; from alfred@FreeBSD.org on Thu, Dec 13, 2001 at 12:08:30PM -0600 References: <20011212125324.R92148@elvis.mu.org> <20011213224148.M469-100000@gamplex.bde.org> <20011213120830.E79896@elvis.mu.org>
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* Alfred Perlstein <alfred@FreeBSD.org> [011213 12:08] wrote:
> * Bruce Evans <bde@zeta.org.au> [011213 05:56] wrote:
> >
> > >From POSIX.1-200x-draft7 (this has not changed since at least the 1990
> > version):
> >
> > ! 36609 When attempting to read from an empty pipe or FIFO:
> > !
> > ! 36610 * If no process has the pipe open for writing, read( ) shall return 0 to indicate end-of-file.
> >
> > The changes make read() block instead, at least for the non-O_NONBLOCK case.
> > I'm not sure of the effect of the change in the O_NONBLOCK case, but it
> > seems likely that -1/EAGAIN is returned instead of 0/no-error.
>
> Ok, I can fix this. (I hope :) )
Can people take a look at this fix? It seems to dtrt, but I need feedback
here.
It basically backs out my last two revisions and changes the hacks the
poll call to seemingly do the right thing.
Index: fifo_vnops.c
===================================================================
RCS file: /home/ncvs/src/sys/fs/fifofs/fifo_vnops.c,v
retrieving revision 1.57
diff -u -r1.57 fifo_vnops.c
--- fifo_vnops.c 12 Dec 2001 09:35:33 -0000 1.57
+++ fifo_vnops.c 15 Dec 2001 21:25:30 -0000
@@ -199,6 +199,7 @@
}
fip->fi_readers = fip->fi_writers = 0;
wso->so_snd.sb_lowat = PIPE_BUF;
+ rso->so_state |= SS_CANTRCVMORE;
}
if (ap->a_mode & FREAD) {
fip->fi_readers++;
@@ -283,11 +284,6 @@
VOP_UNLOCK(ap->a_vp, 0, td);
error = soreceive(rso, (struct sockaddr **)0, uio, (struct mbuf **)0,
(struct mbuf **)0, (int *)0);
- /*
- * Clear EOF indication after first such return.
- */
- if (uio->uio_resid == startresid)
- rso->so_state &= ~SS_CANTRCVMORE;
vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, td);
if (ap->a_ioflag & IO_NDELAY)
rso->so_state &= ~SS_NBIO;
@@ -455,13 +451,23 @@
} */ *ap;
{
struct file filetmp;
- int revents = 0;
+ int s, revents = 0;
if (ap->a_events & (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND)) {
+ struct socket *so;
+ int oflg;
+
filetmp.f_data = (caddr_t)ap->a_vp->v_fifoinfo->fi_readsock;
+ so = (struct socket *)filetmp.f_data;
+ s = splnet();
+ oflg = so->so_state & SS_CANTRCVMORE;
+ if (ap->a_vp->v_fifoinfo->fi_writers == 0)
+ so->so_state &= ~SS_CANTRCVMORE;
if (filetmp.f_data)
revents |= soo_poll(&filetmp, ap->a_events, ap->a_cred,
ap->a_td);
+ so->so_state |= oflg;
+ splx(s);
}
if (ap->a_events & (POLLOUT | POLLWRNORM | POLLWRBAND)) {
filetmp.f_data = (caddr_t)ap->a_vp->v_fifoinfo->fi_writesock;
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