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From: Richard Kettlewell <rjk@terraraq.org.uk>
To: submit@bugs.debian.org
Subject: xemacs21 and terminal settings
X-Mailer: VM 6.72 under 21.1 (patch 10) "Capitol Reef" XEmacs Lucid
Delivered-To: submit@bugs.debian.org

Package: xemacs21
Version: 21.1.10-5

This bug occurs when logging into a Debian machine via SSH from an
xterm running on a Red Hat 7.0 system.

Here is the output of stty when I log in:

chiark$ stty -a
speed 38400 baud; rows 52; columns 80; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
eol2 = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W;
lnext = ^V; flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 -hupcl -cstopb cread -clocal -crtscts
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff
-iuclc -ixany -imaxbel
opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt

Here is the output of stty while xemacs21 is running:

chiark$ stty -a < /dev/pts/97
speed 38400 baud; rows 52; columns 80; line = 0;
intr = ^G; quit = ^G; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
eol2 = <undef>; start = M-^?; stop = M-^?; susp = M-^?; rprnt = M-^?;
werase = M-^?; lnext = M-^?; flush = M-^?; min = 1; time = 0;
-parenb -parodd cs8 -hupcl -cstopb cread -clocal -crtscts
ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff
-iuclc -ixany -imaxbel
opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig -icanon -iexten -echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
echoctl echoke

Notice that "susp = M-^?", i.e. character 255.

When I hit ALT + the <-- key, Redhat's xterm sends byte 255.  XEmacs
gets a suspend signal and immediately stops; when it is continued it
fails to reset the terminal settings (it appears to remain in line
input mode rather than character input mode), and so becomes unusable.

XEmacs should turn off the characters it doesn't want, with the
equivalent of "stty erase undef", rather than set them to silly
values.

It may be trying to do this but using the wrong number; strace
suggests that Linux's stty appears uses 0 rather than 255 to represent
undefined special characters.

On the (remote) Debian system:

 ii  xemacs21       21.1.10-5      Editor and kitchen sink
 ii  xemacs21-bases 1999.12.15-1   Editor and kitchen sink -- elisp support fil
 ii  xemacs21-bin   21.1.10-5      Editor and kitchen sink -- support binaries
 ii  xemacs21-nomul 21.1.10-5      Editor and kitchen sink -- Non-mule binary
 ii  xemacs21-suppo 21.1.10-5      Editor and kitchen sink -- architecture inde
 ii  shellutils     2.0-7          The GNU shell programming utilities.
 ii  ssh            1.2.3-9.2.2    Secure rlogin/rsh/rcp replacement (OpenSSH)

 chiark$ uname -a
 Linux chiark 2.2.19 #1 Wed Mar 28 12:26:51 BST 2001 i586 unknown

On the (local) Red Hat system:

 richard$ ssh -V
 SSH Version OpenSSH_2.3.0p1, protocol versions 1.5/2.0.
 Compiled with SSL (0x0090581f).

 richard$ cat /etc/redhat-release 
 Red Hat Linux release 7.0 (Guinness)

 richard$ uname -a
 Linux persephone.cam.zeus.com 2.4.8 #1 Tue Aug 14 12:46:12 BST 2001 i686 unknown

 richard$ xterm -version
 XFree86 4.0.1(139)

ttfn/rjk