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Fix crash when backspacing placeholders adjacent to multibyte text (#2674)

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Prevented panics when deleting placeholders near multibyte characters by
clamping the cursor to a valid boundary and using get-based slicing

Added a regression test to ensure backspacing after multibyte text
leaves placeholders intact without crashing

---------

Co-authored-by: Ahmed Ibrahim <aibrahim@openai.com>
This commit is contained in:
mattsu
2025-08-27 10:31:49 +09:00
committed by GitHub
parent b367790d9b
commit bd65c4db87
1 changed files with 86 additions and 14 deletions
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100
codex-rs/tui/src/bottom_pane/chat_composer.rs
View File

@@ -259,7 +259,7 @@ impl ChatComposer {
/// Replace the entire composer content with `text` and reset cursor.
pub(crate) fn set_text_content(&mut self, text: String) {
self.textarea.set_text(&text);
self.textarea.set_cursor(usize::MAX);
self.textarea.set_cursor(0);
self.sync_command_popup();
self.sync_file_search_popup();
}
@@ -407,6 +407,33 @@ impl ChatComposer {
input => self.handle_input_basic(input),
}
}
#[inline]
fn clamp_to_char_boundary(text: &str, pos: usize) -> usize {
let mut p = pos.min(text.len());
if p < text.len() && !text.is_char_boundary(p) {
p = text
.char_indices()
.map(|(i, _)| i)
.take_while(|&i| i <= p)
.last()
.unwrap_or(0);
}
p
}
#[inline]
fn handle_non_ascii_char(&mut self, input: KeyEvent) -> (InputResult, bool) {
if !self.paste_burst_buffer.is_empty() || self.in_paste_burst_mode {
let pasted = std::mem::take(&mut self.paste_burst_buffer);
self.in_paste_burst_mode = false;
self.handle_paste(pasted);
}
self.textarea.input(input);
let text_after = self.textarea.text();
self.pending_pastes
.retain(|(placeholder, _)| text_after.contains(placeholder));
(InputResult::None, true)
}
/// Handle key events when file search popup is visible.
fn handle_key_event_with_file_popup(&mut self, key_event: KeyEvent) -> (InputResult, bool) {
@@ -462,8 +489,10 @@ impl ChatComposer {
// using the flat text and byte-offset cursor API.
let cursor_offset = self.textarea.cursor();
let text = self.textarea.text();
let before_cursor = &text[..cursor_offset];
let after_cursor = &text[cursor_offset..];
// Clamp to a valid char boundary to avoid panics when slicing.
let safe_cursor = Self::clamp_to_char_boundary(text, cursor_offset);
let before_cursor = &text[..safe_cursor];
let after_cursor = &text[safe_cursor..];
// Determine token boundaries in the full text.
let start_idx = before_cursor
@@ -476,7 +505,7 @@ impl ChatComposer {
.find(|(_, c)| c.is_whitespace())
.map(|(idx, _)| idx)
.unwrap_or(after_cursor.len());
let end_idx = cursor_offset + end_rel_idx;
let end_idx = safe_cursor + end_rel_idx;
self.textarea.replace_range(start_idx..end_idx, "");
self.textarea.set_cursor(start_idx);
@@ -624,9 +653,11 @@ impl ChatComposer {
fn insert_selected_path(&mut self, path: &str) {
let cursor_offset = self.textarea.cursor();
let text = self.textarea.text();
// Clamp to a valid char boundary to avoid panics when slicing.
let safe_cursor = Self::clamp_to_char_boundary(text, cursor_offset);
let before_cursor = &text[..cursor_offset];
let after_cursor = &text[cursor_offset..];
let before_cursor = &text[..safe_cursor];
let after_cursor = &text[safe_cursor..];
// Determine token boundaries.
let start_idx = before_cursor
@@ -640,7 +671,7 @@ impl ChatComposer {
.find(|(_, c)| c.is_whitespace())
.map(|(idx, _)| idx)
.unwrap_or(after_cursor.len());
let end_idx = cursor_offset + end_rel_idx;
let end_idx = safe_cursor + end_rel_idx;
// Replace the slice `[start_idx, end_idx)` with the chosen path and a trailing space.
let mut new_text =
@@ -808,6 +839,13 @@ impl ChatComposer {
let has_ctrl_or_alt =
modifiers.contains(KeyModifiers::CONTROL) || modifiers.contains(KeyModifiers::ALT);
if !has_ctrl_or_alt {
// Non-ASCII characters (e.g., from IMEs) can arrive in quick bursts and be
// misclassified by our non-bracketed paste heuristic. To avoid leaving
// residual buffered content or misdetecting a paste, flush any burst buffer
// and insert non-ASCII characters directly.
if !ch.is_ascii() {
return self.handle_non_ascii_char(input);
}
// Update burst heuristics.
match self.last_plain_char_time {
Some(prev) if now.duration_since(prev) <= PASTE_BURST_CHAR_INTERVAL => {
@@ -942,8 +980,9 @@ impl ChatComposer {
/// Attempts to remove an image or paste placeholder if the cursor is at the end of one.
/// Returns true if a placeholder was removed.
fn try_remove_any_placeholder_at_cursor(&mut self) -> bool {
let p = self.textarea.cursor();
// Clamp the cursor to a valid char boundary to avoid panics when slicing.
let text = self.textarea.text();
let p = Self::clamp_to_char_boundary(text, self.textarea.cursor());
// Try image placeholders first
let mut out: Option<(usize, String)> = None;
@@ -955,7 +994,7 @@ impl ChatComposer {
continue;
}
let start = p - ph.len();
if text[start..p] != *ph {
if text.get(start..p) != Some(ph.as_str()) {
continue;
}
@@ -963,7 +1002,11 @@ impl ChatComposer {
let mut occ_before = 0usize;
let mut search_pos = 0usize;
while search_pos < start {
if let Some(found) = text[search_pos..start].find(ph) {
let segment = match text.get(search_pos..start) {
Some(s) => s,
None => break,
};
if let Some(found) = segment.find(ph) {
occ_before += 1;
search_pos += found + ph.len();
} else {
@@ -999,7 +1042,7 @@ impl ChatComposer {
if p + ph.len() > text.len() {
continue;
}
if &text[p..p + ph.len()] != ph {
if text.get(p..p + ph.len()) != Some(ph.as_str()) {
continue;
}
@@ -1007,7 +1050,11 @@ impl ChatComposer {
let mut occ_before = 0usize;
let mut search_pos = 0usize;
while search_pos < p {
if let Some(found) = text[search_pos..p].find(ph) {
let segment = match text.get(search_pos..p) {
Some(s) => s,
None => break 'out None,
};
if let Some(found) = segment.find(ph) {
occ_before += 1;
search_pos += found + ph.len();
} else {
@@ -1042,7 +1089,7 @@ impl ChatComposer {
return None;
}
let start = p - ph.len();
if text[start..p] == *ph {
if text.get(start..p) == Some(ph.as_str()) {
Some(ph.clone())
} else {
None
@@ -1058,7 +1105,7 @@ impl ChatComposer {
if p + ph.len() > text.len() {
return None;
}
if &text[p..p + ph.len()] == ph {
if text.get(p..p + ph.len()) == Some(ph.as_str()) {
Some(ph.clone())
} else {
None
@@ -1907,6 +1954,31 @@ mod tests {
}
}
#[test]
fn backspace_with_multibyte_text_before_placeholder_does_not_panic() {
use crossterm::event::KeyCode;
use crossterm::event::KeyEvent;
use crossterm::event::KeyModifiers;
let (tx, _rx) = unbounded_channel::<AppEvent>();
let sender = AppEventSender::new(tx);
let mut composer =
ChatComposer::new(true, sender, false, "Ask Codex to do anything".to_string());
// Insert an image placeholder at the start
let path = PathBuf::from("/tmp/image_multibyte.png");
composer.attach_image(path, 10, 5, "PNG");
// Add multibyte text after the placeholder
composer.textarea.insert_str("日本語");
// Cursor is at end; pressing backspace should delete the last character
// without panicking and leave the placeholder intact.
composer.handle_key_event(KeyEvent::new(KeyCode::Backspace, KeyModifiers::NONE));
assert_eq!(composer.attached_images.len(), 1);
assert!(composer.textarea.text().starts_with("[image 10x5 PNG]"));
}
#[test]
fn deleting_one_of_duplicate_image_placeholders_removes_matching_entry() {
let (tx, _rx) = unbounded_channel::<AppEvent>();