On Jan 31 16:01, Houder wrote:
> On Tue, 31 Jan 2017 14:16:16, Corinna Vinschen wrote:
> 
> [snip]
> 
> > > I'm not quite sure yet but apparently the problem is in the handling of
> > > VERASE in the termios implementation.  In cooked mode it fills a char
> > > buffer with what has been typed.  The code doesn't know if the bytes in
> > > the buffer are UTF-8 chars or just random bytes.  So VERASE erases
> > > exactly one byte, which means, in case of UTF-8 chars it only erases the
> > > last byte of of a mulitbyte character.
> > >=20
> > > It seems the Linux termios implementation is different in that it
> > > still knows which bytes constitute a single keypress and thus knows
> > > how much byte it has to erase.
> > 
> > Ok, here's what happens on Linux:  The termios code support a flag
> > IUTF8.  This flag determines if the termios code checks for UTF8
> > characters in the input when performing an ERASE.  It checks if the
> > IUTF8 flag is set and if so, it checks in a loop if the just erased byte
> > is a UTF-8 continuation character.  If so, it erases another byte.
> 
> (Thank you for responding -- and your effort thus far).
> 
> Agreed. One byte or more, depending on the "character" ... (which is
> not a problem in case of UTF-8 encoding -- continuation bit).
> 
> Of course, the terminal driver must receive the characters encoded in
> UTF-8.
> 
> Therefore the question is: 'can the same situation be created under
> under Windows?' (does Windows provide the required support?)

This has nothing to do with Windows.  It's the termios implementation
inside Cygwin.  I created a patch introducing the IUTF8 flag as on Linux
as well as a code snippet trying to remove entire utf-8 characters from
the input if the IUTF8 flag is set.  And it's set now by default since
we default to UTF-8 anyway.

Thomas, you may want to check for the IUTF8 flag in upcoming mintty
versions and unset it if character set configured in the mintty options
dialog is != UTF-8.

I uploaded new developer snapshots to https://cygwin.com/snapshots/
with this patch.  I'm also going to release a Cygwin test version
later today.


HTH,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat