Problem:
Terminals should respond with the terminator (either BEL or ST) used in
the query so that clients can reliably parse the responses. The
`TermRequest` autocmd used to handle background color requests in the
terminal does not have access to the original sequence terminator, so it
always uses BEL. #37018
Solution:
Update vterm parsing to include the terminator type, then forward this
data into the emitted `TermRequest` events for OSC/DCS/APC sequences.
Update the foreground/background `TermRequest` callback to use the same
terminator as the original request.
Details:
I didn't add the terminator to the `TermResponse` event. However, I
assume the `TermResponse` event doesn't care about the terminator
because the sequence is already parsed. I also didn't update any of the
functions in `src/nvim/vterm/state.c` that write out responses. It
looked like those all pretty much used ST, and it would be a much larger
set of changes. In that same file, there's also logic for 8 bit ST
sequences, but from what I can tell, 8 bit doesn't really work (see `:h
xterm-8bit`), so I didn't use the 8 bit ST at all.
These are not needed after #35129 but making uncrustify still play nice
with them was a bit tricky.
Unfortunately `uncrustify --update-config-with-doc` breaks strings
with backslashes. This issue has been reported upstream,
and in the meanwhile auto-update on every single run has been disabled.
Problem:
Currently undefined behavior can occur when `string_fragment()` is
called with `OSC_COMMAND`. This is because when the state changes to
`OSC_COMMAND`, `string_initial` is set to true. Then in some cases,
directly after this `string_initial` will be set back to false before
the on_osc callback is called, this leads to `term_settermprop()` never
initializing the title.
Solution:
In all of the no-op cases in `string_fragment()` currently, we continue
to the end of the function where `vt->parser.string_initial` is set to
false. This change returns in the no-op cases instead since in these
cases the string has not yet been terminated and sent to the callback.
Note:
This change also adds a test with a byte sequence from the file
in #34028 that caused nvim to crash. This byte sequences is the shortest
sequence I could trim down from that file that still would trigger the
crash. There are also two other tests I added which validate that
setting the title with OSC-0 and OSC-2 still works.
Fixes: #34028
