bug#1006: garbled unicode characters in M-x term

bug#1006: garbled unicode characters in M-x term

[Chong Yidong]

> Ok, I think I found the problem. term uses `binary' as input coding.
> After it has examined the input, it inserts the relevant/visible parts
> of it into the buffer. Only at this point it decodes the bytes with
> the apropriate coding (variable:locale-coding-system).  At some point
> it splits the input string, to make it suitable for the with of the
> `terminal'. The problem is, that it measures bytes not characters. So
> the 3-byte character in question in aptitude, which is mostly on the
> last column, gets split in 2 strings a 1 and 2 byte. This 2 strings,
> when encoded and inserted independently, will result in what was
> described as the problem.

Thanks for the analysis.  Could you try to write a patch to fix this?

bug#1006: garbled unicode characters in M-x term

[Andreas Politz]

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the bug-gnu-emacs@gnu.org mailing list,
and to the gnu.emacs.bug news group.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:


Problem : Under certain circumstances multibyte characters in M-x term
become garbled and display as single byte escape sequences.

Example : debians aptitude (character U+2592)

 From a post I made to gnu.emacs.help:

Ok, I think I found the problem. term uses `binary' as input coding.
After it has examined the input, it inserts the relevant/visible parts
of it into the buffer. Only at this point it decodes the bytes with
the apropriate coding (variable:locale-coding-system).
At some point it splits the input string, to make it suitable for the
with of the `terminal'. The problem is, that it measures bytes not
characters. So the 3-byte character in question in aptitude, which is mostly
on the last column, gets split in 2 strings a 1 and 2 byte. This 2
strings, when encoded and inserted independently, will result in
what was described as the problem.

Solution would be to encode the string before checking the length of
it.

-ap

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
     `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/share/emacs/22.2/etc/DEBUG for instructions.


In GNU Emacs 22.2.1 (i486-pc-linux-gnu, GTK+ Version 2.12.11)
  of 2008-07-25 on raven, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
configured using `configure  '--build=i486-linux-gnu' '--host=i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var/lib' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs22:/etc/emacs:/usr/local/share/emacs/22.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/22.2/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/22.2/leim' '--with-x=yes' '--with-x-toolkit=gtk' '--with-toolkit-scroll-bars' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -g -O2' 'LDFLAGS=-g' 'CPPFLAGS=''

Important settings:
   value of $LC_ALL: nil
   value of $LC_COLLATE: nil
   value of $LC_CTYPE: nil
   value of $LC_MESSAGES: nil
   value of $LC_MONETARY: nil
   value of $LC_NUMERIC: nil
   value of $LC_TIME: nil
   value of $LANG: en_US.UTF-8
   locale-coding-system: utf-8
   default-enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
   shell-dirtrack-mode: t
   auto-fill-function: do-auto-fill
   show-paren-mode: t
   savehist-mode: t
   icomplete-mode: t
   global-hi-lock-mode: t
   hi-lock-mode: t
   display-time-mode: t
   tooltip-mode: t
   mouse-wheel-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   unify-8859-on-encoding-mode: t
   utf-translate-cjk-mode: t
   auto-compression-mode: t
   column-number-mode: t
   line-number-mode: t

Recent input:
C-x C-s M-x d i f f SPC u DEL C-g C-x o M-? m C-M-v
C-x k RET C-x C-g M-x d i f f RET RET t e r m . RET
C-x o C-v C-v C-v C-v C-v M-< M-x w o m a n RET d i
f f RET C-v C-v C-v M-v C-r i g n o r e C-r C-g C-x
b t e r C-s C-s C-g C-x o M-x C-g C-u M-x d i f f RET
RET t e r C-s RET w <return> C-x o C-n C-n C-n C-n
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n
C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-p C-x o C-x
o M-< C-x k RET C-x o C-u M-x d i f f RET RET t e r
C-s RET DEL w <return> C-x C-g C-u C-g M-x d i f f
RET RET t e r m . RET C-x o C-v C-v C-v C-v C-v M-v
M-v M-v M-v M-v C-x o C-x C-w ~ / . e m / t e r m .
e l <return> C-x b f o RET C-n C-n C-n C-n C-n C-n
C-n C-n C-n C-n M-x r e p o SPC r t RET g r a <backspace>
<backspace> a r b e l e d DEL DEL DEL DEL l e d C-g

Recent messages:
Repeating command 1 other-window
Quit
Repeating command 1 other-window [2 times]
Saving file /home/andy/.emacs.d/term.el...
Wrote /home/andy/.emacs.d/term.el
Making completion list...
Loading emacsbug...done
Quit