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Fixed EOF handing.

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1. SS_CANTRCVMORE was initially set on the wrong socket, so reads
when there has never been a writer on the socket did not return 0.
Note that such reads are only possible if the fifo was opened in
(O_RDONLY | O_NONBLOCK) mode.

2. SS_CANTSENDMORE was initially set on the wrong socket, but this
was harmless because the wrong socket is never sent from and there
is no need to set the flag initially on the right socket (since open
in (O_WRONLY | O_NONBLOCK) mode fails if there is no reader...).

3. SS_CANTRCVMORE was cleared when read() returns.  This broke the
case where read() returns 0 - subsequent reads are supposed to
return 0 until a writer appears.  There is no need to clear the
flag when read() returns, since it is cleared correctly when a
writer appears.
This commit is contained in:
Bruce Evans 1997-12-13 13:49:59 +00:00
parent 5fb0d3e0b3
commit 80987b7a3b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=31701
2 changed files with 4 additions and 16 deletions
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10
sys/fs/fifofs/fifo_vnops.c
View file

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
* $Id: fifo_vnops.c,v 1.38 1997/12/05 19:55:46 bde Exp $
* $Id: fifo_vnops.c,v 1.39 1997/12/13 12:58:09 bde Exp $
*/
#include <sys/param.h>
@ -189,8 +189,7 @@ fifo_open(ap)
return (error);
}
fip->fi_readers = fip->fi_writers = 0;
wso->so_state |= SS_CANTRCVMORE;
rso->so_state |= SS_CANTSENDMORE;
rso->so_state |= SS_CANTRCVMORE;
}
if (ap->a_mode & FREAD) {
fip->fi_readers++;
@ -272,11 +271,6 @@ fifo_read(ap)
error = soreceive(rso, (struct sockaddr **)0, uio, (struct mbuf **)0,
(struct mbuf **)0, (int *)0);
vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, p);
/*
* Clear EOF indication after first such return.
*/
if (uio->uio_resid == startresid)
rso->so_state &= ~SS_CANTRCVMORE;
if (ap->a_ioflag & IO_NDELAY)
rso->so_state &= ~SS_NBIO;
return (error);

10
sys/miscfs/fifofs/fifo_vnops.c
View file

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)fifo_vnops.c 8.10 (Berkeley) 5/27/95
* $Id: fifo_vnops.c,v 1.38 1997/12/05 19:55:46 bde Exp $
* $Id: fifo_vnops.c,v 1.39 1997/12/13 12:58:09 bde Exp $
*/
#include <sys/param.h>
@ -189,8 +189,7 @@ fifo_open(ap)
return (error);
}
fip->fi_readers = fip->fi_writers = 0;
wso->so_state |= SS_CANTRCVMORE;
rso->so_state |= SS_CANTSENDMORE;
rso->so_state |= SS_CANTRCVMORE;
}
if (ap->a_mode & FREAD) {
fip->fi_readers++;
@ -272,11 +271,6 @@ fifo_read(ap)
error = soreceive(rso, (struct sockaddr **)0, uio, (struct mbuf **)0,
(struct mbuf **)0, (int *)0);
vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, p);
/*
* Clear EOF indication after first such return.
*/
if (uio->uio_resid == startresid)
rso->so_state &= ~SS_CANTRCVMORE;
if (ap->a_ioflag & IO_NDELAY)
rso->so_state &= ~SS_NBIO;
return (error);