Date: Wed, 15 May 1996 02:01:34 +1000 From: Bruce Evans <bde@zeta.org.au> To: freebsd-hackers@FreeBSD.org, tom@uces.bangor.ac.uk Subject: Re: write and pty's Message-ID: <199605141601.CAA10288@godzilla.zeta.org.au>
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>...
>After some hours with xxgdb and libraries compiled with debugging symbols,
>I tracked the problem to a write call. This write call returns 0 even
>though it appears that a charater has been written. The fact that this
>call returns 0 means that the write pointer in the cmdtool code is not
>updated and so it is written again etc. (you get the picture)
>...
>I am running FreeBSD-2.2-SNAP 960128 with the xview-3.2 patched for X11R6.
>The problem also exists on 2.1-RELEASE.
This should be fixed in current SNAPs and stables (versions after April 11).
It happened for most writes of more than about 100 bytes if PF_REMOTE was set.
Bruce
Index: tty_pty.c
===================================================================
RCS file: /a/ncvs/src/sys/kern/tty_pty.c,v
retrieving revision 1.37
retrieving revision 1.38
diff -c -1 -r1.37 -r1.38
*** tty_pty.c 1996/03/11 02:24:39 1.37
--- tty_pty.c 1996/04/11 18:43:37 1.38
***************
*** 33,35 ****
* @(#)tty_pty.c 8.4 (Berkeley) 2/20/95
! * $Id: tty_pty.c,v 1.37 1996/03/11 02:24:39 hsu Exp $
*/
--- 33,35 ----
* @(#)tty_pty.c 8.4 (Berkeley) 2/20/95
! * $Id: tty_pty.c,v 1.38 1996/04/11 18:43:37 bde Exp $
*/
***************
*** 536,539 ****
}
! if (cc)
! cc -= b_to_q((char *)cp, cc, &tp->t_canq);
}
--- 536,550 ----
}
! if (cc > 0) {
! cc = b_to_q((char *)cp, cc, &tp->t_canq);
! /*
! * XXX we don't guarantee that the canq size
! * is >= TTYHOG, so the above b_to_q() may
! * leave some bytes uncopied. However, space
! * is guaranteed for the null terminator if
! * we don't fail here since (TTYHOG - 1) is
! * not a multiple of CBSIZE.
! */
! if (cc > 0)
! break;
! }
}
***************
*** 576,578 ****
* Come here to wait for slave to open, for space
! * in outq, or space in rawq.
*/
--- 587,589 ----
* Come here to wait for slave to open, for space
! * in outq, or space in rawq, or an empty canq.
*/
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