This commit fixes the following:
1. Emacs mode ignores --nobackslashctrl (re: 24598fed) when in
reverse search.
2. When entering more than one backslash, emacs reverse search mode
deletes multiple backslashes after pressing backspace once.
Reproducer:
$ set --emacs --nobackslashctrl
$ <Ctrl+R> \\\\<Backspace>
3. Except when in reverse search, the backslash fails to escape a
subsequent interrupt character (^C). Reproducer:
$ set --emacs --backslashctrl
$ teststring \<Ctrl+C>
src/cmd/ksh93/edit/emacs.c:
- Disable escaping backslashes in emacs reverse search if
'nobackslashctrl' is enabled.
- Fix the buggy behavior of backslashes in emacs reverse
search by processing backslashes in a loop.
src/cmd/ksh93/tests/pty.sh:
- Add regression tests.
src/cmd/ksh93/sh.1:
- Fix a minor documentation error (^C is the usual interrupt
character, not ^?).
Co-authored-by: Martijn Dekker <martijn@inlv.org>