ports/114782: Incorrect cursor behavior during command line editing in bash shell using UTF-8

[Joe Peterson]

>Number:         114782
>Category:       ports
>Synopsis:       Incorrect cursor behavior during command line editing in bash shell using UTF-8
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jul 20 20:30:02 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Joe Peterson
>Release:        6.2
>Organization:
>Environment:
FreeBSD crater 6.2-RELEASE FreeBSD Gentoo 6.2-r1 #1: Sat Jul  7 15:24:52 MDT 2007     joe at crater:/usr/src/sys-6.2-r1/i386/compile/GENERIC  i386
>Description:
In the bash shell, if you have LANG set to en_US.UTF-8 (or any UTF-8 variant) and you use the right arrow to move the cursor "past" the end of a command line (i.e. if you try to go even farther than the end - the cursor will not actually appear to go past the end), subsequently hitting left arrow the first time does nothing, whereas hitting it again will go back one - it is as if there is an invisible char at the end or something.  Other manifestations of this will have the cursor go back and forth repeatedly (left, right, left, right) as you hit right arrow at the end of the line.  Also, if you have "gone past the end", typing any characters will have not effect and will not be seen, which can be confusing.  Specific behaviors can differ slightly either randomly or if done on different previous command lines (i.e. up-arrow through history).

Note that I am using Gentoo/FreeBSD, but Frank J. Lazlo (laszlof at FreeBSD.org) has reproduced this for me on standard FreeBSD.  It never seems to happen in Linux.
>How-To-Repeat:
1) Enter bash
2) Type: "export LANG=en_US.UTF-8"
3) Type a couple of characters, and then hit right arrow (or ctrl-f) followed
by left arrow (ctrl-b).  If the cursor doesn't move back one on the first
left-arrow, but does on the second, you are seeing the issue.

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: