Cancel key reading when 'execute' triggered via a server request by junegunn · Pull Request #4653 · junegunn/fzf

junegunn · 2026-01-02T16:39:23Z

Note:

Using poll() would simplify the code, but on macOS it just returns POLLNVAL for /dev/tty.

The poll() system call currently does not support devices.

Fix #4524 (except on Windows)

Copilot

Pull request overview

This PR implements the ability to cancel blocking key reading operations when an 'execute' action is triggered via a server request, addressing issue #4524. The implementation is complete for Unix-like systems but remains unimplemented for Windows (as noted in the TODO comments).

Added CancelGetChar() method to the Renderer interface
Implemented cancellation mechanism for Unix using pipes and select system call
Updated return types from bool to getCharResult enum to handle cancellation state
Modified terminal event loop to call CancelGetChar() when execute actions arrive from server

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/tui/tui.go	Added `CancelGetChar()` method to Renderer interface
src/tui/tcell.go	Added stub `CancelGetChar()` implementation with TODO for future work
src/tui/light_windows.go	Updated `getch()` return type from bool to `getCharResult` enum
src/tui/light_unix.go	Implemented `getch()` cancellation using pipes and select, updated return type to `getCharResult` enum
src/tui/light.go	Added `getCharResult` type, `cancel` function field, and `CancelGetChar()` implementation; updated all related functions to handle cancellation
src/tui/dummy.go	Added empty `CancelGetChar()` stub for dummy renderer
src/terminal.go	Added logic to call `CancelGetChar()` when execute action is received from server

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Copilot

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.

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Copilot · 2026-01-08T15:19:55Z

 }

+func (r *FullscreenRenderer) CancelGetChar() {
+	// TODO


The CancelGetChar method for tcell renderer is not implemented (marked as TODO). This means that when using the tcell-based renderer, the execute action triggered via server requests will not be able to cancel a blocking GetChar call. Consider implementing this using tcell's event posting mechanism or document this limitation.

Suggested change

// TODO

// Use tcell's event posting mechanism to interrupt a blocking PollEvent/GetChar.

if _screen != nil {

_screen.PostEvent(tcell.NewEventInterrupt(nil))

}

Copilot · 2026-01-08T15:19:56Z

 }

-func (r *FullscreenRenderer) GetChar() Event {
+func (r *FullscreenRenderer) GetChar(cancellable bool) Event {


The cancellable parameter is not used in this implementation. Since CancelGetChar is not implemented for tcell (marked as TODO), this parameter should either be documented as unused or the cancellation functionality should be implemented.

Suggested change

func (r *FullscreenRenderer) GetChar(cancellable bool) Event {

// GetChar blocks until an event is available. The cancellable parameter is

// ignored in the tcell implementation; cancellation is not supported here.

func (r *FullscreenRenderer) GetChar(_ bool) Event {

Copilot · 2026-01-08T15:19:56Z

 	showCursor    bool
+	mutex         sync.Mutex

 	// Windows only


The comment "// Windows only" is now misleading since the mutex field (line 135) is used on all platforms for protecting the cancel function. Consider updating this comment to reflect that only the fields from ttyinChannel onwards are Windows-specific.

Suggested change

// Windows only

// Windows-specific fields (from ttyinChannel onwards)

Copilot · 2026-01-08T15:19:57Z

+		return getter()
+	}
+	r.setCancel(func() {
+		wpipe.Write([]byte{0})


The write to wpipe in the cancel function does not check for errors. While this is generally acceptable for a cancellation signal, if the write fails (e.g., pipe buffer full or pipe closed due to a race condition), it will silently fail. Consider ignoring the error explicitly with a blank identifier to make the intention clear.

Suggested change

wpipe.Write([]byte{0})

_, _ = wpipe.Write([]byte{0})

Copilot · 2026-01-08T15:19:57Z

+	go func() {
+		for {
+			light_renderer.mutex.Lock()
+			ready := light_renderer.cancel != nil
+			light_renderer.mutex.Unlock()
+
+			if ready {
+				light_renderer.CancelGetChar()
+				break
+			}
+		}


This test uses a busy-wait loop that repeatedly locks and unlocks the mutex, which is inefficient and could cause unnecessary CPU usage. Consider using a synchronization primitive like a channel or sync.WaitGroup to signal when the cancel function is ready, or add a small sleep in the loop to reduce CPU usage.

…egunn#4653) Fix junegunn#4524 Close junegunn#4648

This MR contains the following updates: | Package | Update | Change | |---|---|---| | [junegunn/fzf](https://github.com/junegunn/fzf) | minor | `v0.67.0` → `v0.68.0` | MR created with the help of [el-capitano/tools/renovate-bot](https://gitlab.com/el-capitano/tools/renovate-bot). **Proposed changes to behavior should be submitted there as MRs.** --- ### Release Notes <details> <summary>junegunn/fzf (junegunn/fzf)</summary> ### [`v0.68.0`](https://github.com/junegunn/fzf/releases/tag/v0.68.0): 0.68.0 [Compare Source](junegunn/fzf@v0.67.0...v0.68.0) <https://github.com/user-attachments/assets/8d9e6e29-1bde-49d3-b580-c560da394a5d> - Implemented word wrapping in the list section - Added `--wrap=word` (or `--wrap-word`) option and `toggle-wrap-word` action for word-level line wrapping in the list section - Changed default binding of `ctrl-/` and `alt-/` from `toggle-wrap` to `toggle-wrap-word` ```sh fzf --wrap=word ``` - Implemented word wrapping in the preview window - Added `wrap-word` flag for `--preview-window` to enable word-level wrapping - Added `toggle-preview-wrap-word` action ```sh fzf --preview 'bat --style=plain --color=always {}' \ --preview-window wrap-word \ --bind space:toggle-preview-wrap-word ``` - Added support for underline style variants in `--color`: `underline-double`, `underline-curly`, `underline-dotted`, `underline-dashed` ```sh fzf --color 'fg:underline-curly,current-fg:underline-dashed' ``` - Added support for underline styles (`4:N`) and underline colors (SGR 58/59) ```sh # In the list section printf '\e[4:3;58;2;255;0;0mRed curly underline\e[0m\n' | fzf --ansi # In the preview window fzf --preview "printf '\e[4:3;58;2;255;0;0mRed curly underline\e[0m\n'" ``` - Added `--preview-wrap-sign` to set a different wrap indicator for the preview window - Added `alt-gutter` color option ([#4602](junegunn/fzf#4602)) ([@hedgieinsocks](https://github.com/hedgieinsocks)) - Added `$FZF_WRAP` environment variable to child processes (`char` or `word` when wrapping is enabled) ([#4672](junegunn/fzf#4672)) ([@bitraid](https://github.com/bitraid)) - fish: Improved command history (CTRL-R) ([#4672](junegunn/fzf#4672)) ([@bitraid](https://github.com/bitraid)) - Enabled syntax highlighting in the list on fish 4.3.3+ - Added syntax-highlighted preview window that auto-shows for long or multi-line commands - Added `ALT-ENTER` to reformat and insert selected commands - Improved handling of bulk deletion of selected history entries (`SHIFT-DELETE`) - Added fish completion support ([#4605](junegunn/fzf#4605)) ([@lalvarezt](https://github.com/lalvarezt)) - zsh: Handle multi-line history selection ([#4595](junegunn/fzf#4595)) ([@LangLangBart](https://github.com/LangLangBart)) - Bug fixes - Fixed `_fzf_compgen_{path,dir}` to respect `FZF_COMPLETION_{PATH,DIR}_OPTS` ([#4592](junegunn/fzf#4592)) ([@shtse8](https://github.com/shtse8), [@LangLangBart](https://github.com/LangLangBart)) - Fixed `--preview-window follow` not working correctly with wrapping ([#3243](junegunn/fzf#3243), [#4258](junegunn/fzf#4258)) - Fixed symlinks to directories being returned as files ([#4676](junegunn/fzf#4676)) ([@skk64](https://github.com/skk64)) - Fixed SIGHUP signal handling ([#4668](junegunn/fzf#4668)) ([@LangLangBart](https://github.com/LangLangBart)) - Fixed preview process not killed on exit ([#4667](junegunn/fzf#4667)) - Fixed coloring of items with zero-width characters ([#4620](junegunn/fzf#4620)) - Fixed `track-current` unset after a combined movement action ([#4649](junegunn/fzf#4649)) - Fixed `--accept-nth` being ignored in filter mode ([#4636](junegunn/fzf#4636)) ([@charemma](https://github.com/charemma)) - Fixed display width calculation with `maxWidth` ([#4596](junegunn/fzf#4596)) ([@LangLangBart](https://github.com/LangLangBart)) - Fixed clearing of the rest of the current line on start ([#4652](junegunn/fzf#4652)) - Fixed `x-api-key` header not required for GET requests ([#4627](junegunn/fzf#4627)) - Fixed key reading not cancelled when `execute` triggered via a server request ([#4653](junegunn/fzf#4653)) - Fixed rebind of readline command `redraw-current-line` ([#4635](junegunn/fzf#4635)) ([@jameslazo](https://github.com/jameslazo)) - Fixed `fzf-tmux` `TERM` quoting and added `mktemp` usage ([#4664](junegunn/fzf#4664)) ([@Goofygiraffe06](https://github.com/Goofygiraffe06)) - Do not allow very long queries in `FuzzyMatchV2` ([#4608](junegunn/fzf#4608)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this MR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this MR, check this box --- This MR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).

Cancel key reading when 'execute' triggered via a server request

5e3ccb4

Fix #4524 (except on Windows)

junegunn self-assigned this Jan 2, 2026

junegunn requested a review from Copilot January 2, 2026 16:39

Copilot started reviewing on behalf of junegunn January 2, 2026 16:39 View session

Copilot AI reviewed Jan 2, 2026

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Comment thread src/tui/light_unix.go Outdated

junegunn added 5 commits January 3, 2026 10:16

Fallback to blocking read without cancellation

728117b

Implement key reading cancellation on Windows

2cc3697

Replace syscall.Select with unix.Select

64b338a

Prevent panic from fd overflow

c05f898

Fix unit test

a87dea5

junegunn added the bug Something isn't working label Jan 3, 2026

junegunn marked this pull request as ready for review January 3, 2026 07:59

Refactor

57f2ed4

junegunn force-pushed the cancel-key-reading branch from 47df19c to 57f2ed4 Compare January 4, 2026 00:24

junegunn added 2 commits January 4, 2026 09:44

Refactor windows code

2dcf1fa

Limit the number of select() retries

2df6503

junegunn requested a review from Copilot January 8, 2026 15:15

Copilot started reviewing on behalf of junegunn January 8, 2026 15:15 View session

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junegunn merged commit 3f94bcb into master Jan 8, 2026
11 checks passed

junegunn deleted the cancel-key-reading branch January 8, 2026 15:29

eli-percepto pushed a commit to eli-percepto/fzf that referenced this pull request Feb 3, 2026

Cancel key reading when 'execute' triggered via a server request (jun…

3c16922

…egunn#4653) Fix junegunn#4524 Close junegunn#4648

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Cancel key reading when 'execute' triggered via a server request#4653

Cancel key reading when 'execute' triggered via a server request#4653
junegunn merged 9 commits into
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junegunn commented Jan 2, 2026 •

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-	// TODO
+	// Use tcell's event posting mechanism to interrupt a blocking PollEvent/GetChar.
+	if _screen != nil {
+		_screen.PostEvent(tcell.NewEventInterrupt(nil))
+	}

-func (r *FullscreenRenderer) GetChar(cancellable bool) Event {
+// GetChar blocks until an event is available. The cancellable parameter is
+// ignored in the tcell implementation; cancellation is not supported here.
+func (r *FullscreenRenderer) GetChar(_ bool) Event {

	// Windows only
	// Windows-specific fields (from ttyinChannel onwards)

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junegunn commented Jan 2, 2026 •

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