Subject: kern/11827: wscons vt100 emulation botches scroll region
To: None <gnats-bugs@gnats.netbsd.org>
From: None <sommerfeld@netbsd.org>
List: netbsd-bugs
Date: 12/27/2000 12:25:16
>Number: 11827
>Category: kern
>Synopsis: wscons-vt100 scrolls when outside scroll region
>Confidential: yes
>Severity: serious
>Priority: medium
>Responsible: kern-bug-people
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Wed Dec 27 12:25:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator: Bill Sommerfeld
>Release: 200012xx
>Organization:
>Environment:
System: NetBSD syn 1.5O NetBSD 1.5O (VAIO) #7: Wed Dec 27 15:06:41 EST 2000 wes@syn:/usr/wes/vanilla-sys/arch/i386/compile/VAIO i386
>Description:
This bug was noticed by Richard Tibbetts <tibbetts@mit.edu>
wscons output involving a newline or line wrap below the scroll region
forces the screen to scroll; this does not match (e.g.) xterm
behavior.
>How-To-Repeat:
uudecode the following, and send to
a) an xterm.
b) wscons running in 80x50 mode.
Observe that the final screen state is not the same.
begin 664 screen-bug-test
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M2!M;2AM;-#E"&ULW;2`M+2`@("`@("`@("`@("`@("`@("`@("`@("`@("`@
M("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@
M("`@&ULR-VT;6T@;6T@;6TH;6S0Y0AM;-VTQ,SHP,R`\/B`@("`@("`@("`@
M("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@("`@
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M7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7PTM7QM;,S5M
M*C(^86QE='1A&ULS-FU?,3YT:6)B971T<U]?7U]?7U]?7U]?7U]?7U]?7U]?
L7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7U]?7PT*&ULR00I?
`
end
>Fix:
This appears to fix the problem but has not been extensively tested;
also, the code sequence in question should probably be refactored as
it occurrs 3 times in the driver.
The current logic is:
scroll if we are at or below the bottom of the
scroll region, otherwise move down a line
The enclosed patch changes this to:
scroll if we are at the bottom of the scroll region,
otherwise, move down a line if we are not at the bottom of the
screen.
It is not clear if the "move down a line if outside the scroll region"
behavior of the patch is correct; however, the existing behavior is
clearly incorrect.
Index: wsemul_vt100.c
===================================================================
RCS file: /cvsroot/syssrc/sys/dev/wscons/wsemul_vt100.c,v
retrieving revision 1.13
diff -u -r1.13 wsemul_vt100.c
--- wsemul_vt100.c 2000/04/28 21:56:16 1.13
+++ wsemul_vt100.c 2000/12/27 20:15:17
@@ -324,11 +324,13 @@
if ((edp->flags & (VTFL_LASTCHAR | VTFL_DECAWM)) ==
(VTFL_LASTCHAR | VTFL_DECAWM)) {
- if (ROWS_BELOW > 0) {
- edp->crow++;
+ if (ROWS_BELOW == 0) {
+ wsemul_vt100_scrollup(edp, 1);
+ } else {
+ if ((edp->crow+1) < edp->nrows)
+ edp->crow++;
CHECK_DW;
- } else
- wsemul_vt100_scrollup(edp, 1);
+ }
edp->ccol = 0;
edp->flags &= ~VTFL_LASTCHAR;
}
@@ -437,11 +439,13 @@
case ASCII_LF:
case ASCII_VT:
case ASCII_FF:
- if (ROWS_BELOW > 0) {
- edp->crow++;
+ if (ROWS_BELOW == 0) {
+ wsemul_vt100_scrollup(edp, 1);
+ } else {
+ if ((edp->crow+1) < edp->nrows)
+ edp->crow++;
CHECK_DW;
- } else
- wsemul_vt100_scrollup(edp, 1);
+ }
break;
}
}
@@ -497,12 +501,13 @@
edp->ccol = 0;
/* FALLTHRU */
case 'D': /* IND */
- if (ROWS_BELOW > 0) {
- edp->crow++;
+ if (ROWS_BELOW == 0) {
+ wsemul_vt100_scrollup(edp, 1);
+ } else {
+ if ((edp->crow+1) < edp->nrows)
+ edp->crow++;
CHECK_DW;
- break;
}
- wsemul_vt100_scrollup(edp, 1);
break;
case 'H': /* HTS */
KASSERT(edp->tabs != 0);
>Release-Note:
>Audit-Trail:
>Unformatted: