[Bug 394570] Re: Backspace via SSH only deletes last byte of characters

[AZaharia]

** Description changed:

  Binary package hint: openssh-client
  
  This is not a terminal-related problem: regardless of the terminal used
  and the way the backspace key is supposed to behave (ASCII DEL, escape
  sequence, Control+H), what happens is that via SSH the backspace key
  only deletes the last byte of a character, not the whole character
  itself.
  
  You can notice this when you use UTF-8 characters that are encoded on
  more than 1 byte. Some diacritics from the Latin alphabet are encoded on
  2 bytes, whereas some Japanese characters are encoded on 3.
  
  As an example, assume the following scenario: the letter "ș" is encoded
  as "c8 99" and endline is encoded as "0a":
  
  user at host:~$ cat > ș.txt
  ș
  ^d
  user at host:~$ hexdump -C ș.txt 
  00000000  c8 99 0a                                          |...|
  00000003
  
  Now, assume you write "testș[hit backspace]test[endline]". On the
  physical host (i.e. without being SSH-ed into it), the hexdump of that
  file will be:
  
  user at host:~$ cat > test.txt
  testș[backspace]test
  ^d
  user at host:~$ hexdump -C test.txt
  00000000  74 65 73 74 74 65 73 74  0a                       |testtest.|
  00000009
  
  whereas the *same* thing via SSH would lead you to having the following
  hexdump:
  
  user at host:~$ ssh user at localhost
  user at localhost's password: 
  user at host:~$ cat > test.txt
  testș[backspace]test
  ^d
  user at host:~$ hexdump -C test.txt
  00000000  74 65 73 74 c8 74 65 73  74 0a                    |test.test.|
  0000000a
  
  So notice how backspace only deleted via SSH the last byte of "ș" i.e.
  only the "99" out of "c8 99"; compare the expected hexdump:
  
  74 65 73 74 74 65 73 74  0a
  
  with the actual hexdump:
  
  74 65 73 74 c8 74 65 73  74 0a
  
  locale is set to en_US.UTF-8; changing it to ro_RO.UTF-8 (both on the
  host and via SSH) yields the same results.
  
  Finally, last details:
  
  Ubuntu 9.04
  Kernel 2.6.28-13-generic
  openssh-client:  Installed: 1:5.1p1-5ubuntu1
  openssh-server:  Installed: 1:5.1p1-5ubuntu1
+ 
+ L.E.: I also tried the same thing using dropbear instead of OpenSSH.

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Backspace via SSH only deletes last byte of characters
https://bugs.launchpad.net/bugs/394570
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