The [disambiguate flag](https://sw.kovidgoyal.net/kitty/keyboard-protocol/#disambiguate) means that:
> In particular, ctrl+c will no longer generate the SIGINT signal,
> but instead be delivered as a CSI u escape code.
so cancellation only works while we turn off disambiguation.
Today we turn it off while running external commands that want to
claim the TTY. Also we do it (only as a workaround for this issue)
while expanding wildcards or while running builtin wait.
However there are other cases where we don't have a workaround,
like in trivial infinite loops or when opening a fifo.
Before we run "while true; end", we put the terminal back in ICANON
mode. This means it's line-buffered, so we won't be able to detect
if the user pressed ctrl-c.
Commit 8164855b7 (Disable terminal protocols throughout evaluation,
2024-04-02) had the right solution: simply disable terminal protocols
whenever we do computations that might take a long time.
eval_node() covers most of that; there are a few others.
As pointed out in #10494, the logic was fairly unsophisticated then:
it toggled terminal protocols many times. The fix in 29f2da8d1
(Toggle terminal protocols lazily, 2024-05-16) went to the extreme
other end of only toggling protocols when absolutely necessary.
Back out part of that commit by toggling in eval_node() again,
fixing cancellation. Fortunately, we can keep most of the benefits
of the lazy approach from 29f2da8d1: we toggle only 2 times instead
of 8 times for an empty prompt.
There are only two places left where we call signal_check_cancel()
without necessarily disabling the disambiguate flag
1. open_cloexec() we assume that the files we open outside eval_node()
are never blocking fifos.
2. fire_delayed(). Judging by commit history, this check is not
relevant for interactive sessions; we'll soon end up calling
eval_node() anyway.
In future, we can leave bracketed paste, modifyOtherKeys and
application keypad mode turned on again, until we actually run an
external command. We really only want to turn off the disambiguate
flag.
Since this is approach is overly complex, I plan to go with either
of these two alternatives in future:
- extend the kitty keyboard protocol to optionally support VINTR,
VSTOP and friends. Then we can drop most of these changes.
- poll stdin for ctrl-c. This promises a great simplification,
because it implies that terminal ownership (term_steal/term_donate)
will be perfectly synced with us enabling kitty keyboard protocol.
This is because polling requires us to turn off ICANON.
I started working on this change; I'm convinced it must work,
but it's not finished yet. Note that this will also want to
add stdin polling to builtin wait.
Closes#10864
On this binding we fail to disable CSI u
bind c-t '
begin
set -lx FZF_DEFAULT_OPTS --height 40% --bind=ctrl-z:ignore
eval fzf | while read -l r; echo read $r; end
end
'
because for "fzf", ParseExecutionContext::setup_group() returns early with the
parent process group (which should be fish's own) , hence "wants_terminal"
is false. This seems questionable, I don't think the eval should make a
difference here.
For now, don't touch it; use the more accurate way of detecting whether
a process may read keyboard input. In many of such cases "wants_terminal"
is false, like
echo (echo 1\n2\n3 | fzf)
Fixes#10504
We sometimes leak ^[[I and ^[[O focus reporting events when run from VSCode's
"Run python file" button in the top right corner. To reproduce I installed
the ms-python extension set the VSCode default shell to fish and repeatedly
ran a script that does "time.sleep(1)". I believe VSCode synthesizes keys
and triggers a race condition.
We can probably fix this but I'm not sure when I'll get to it (given how
relatively unimportant this feature is).
So let's go back to the old behavior of only enabling focus reporting in tmux.
I believe that tmux is affected by the same VSCode issue (also on 3.7.1 I
think) but I haven't been able to get tmux to emit focus reporting sequences
yet. Still, keep it to not regress cursor shape (#4788). So far this is
the only motivation for focus reporting and I believe it is only relevant
for terminals that can split windows (though there are a bunch that do).
Closes#10448
Some terminals send the focus-in sequences ("^[I") whenever focus reporting is
enabled. We enable focus reporting whenever we are finished running a command.
If we run two commands without reading in between, the focus sequences
will show up on the terminal.
Fix this by enabling focus-reporting as late as possible.
This fixes the problem with `^[I` showing up when running "cat" in
gnome-terminal https://github.com/fish-shell/fish-shell/issues/10411.
This begs the question if we should do the same for CSI u and bracketed paste.
It's difficult to answer that; let's hope we find motivating test cases.
If we enable CSI u too late, we might misinterpret key presses, so for now
we still enable those as early as possible.
Also, since we now read immediately after enabling focus events, we can get
rid of the hack where we defer enabling them until after the first prompt.
When I start a fresh terminal, the ^[I no longer shows up.
`read` allows specifying the initial command line text. This was
text got accidentally ignored starting in a32248277f. Fix this
regression and add a test.
Fixes#8633
Note: This includes a super cheesy thing to print variable contents.
The expect version has one that's a bit more elaborate (featuring a
marker setup), but tbh that doesn't seem to be worth it.
If we do need it, we can add it, but it seems more likely we'd just do
`set -S`, or do it in a check instead.
