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## Summary Fixes #24147 - Fixed EventEmitter crash when `removeAllListeners()` is called from within an event handler while a `removeListener` meta-listener is registered - Added undefined check before iterating over listeners array to match Node.js behavior - Added comprehensive regression tests ## Bug Description When `removeAllListeners(type)` was called: 1. From within an event handler 2. While a `removeListener` meta-listener was registered 3. For an event type with no listeners It would crash with: `TypeError: undefined is not an object (evaluating 'this._events')` ## Root Cause The `removeAllListeners` function tried to access `listeners.length` without checking if `listeners` was defined first. When called with an event type that had no listeners, `events[type]` returned `undefined`, causing the crash. ## Fix Added a check `if (listeners !== undefined)` before iterating, matching the behavior in Node.js core: https://github.com/nodejs/node/blob/main/lib/events.js#L768 ## Test plan - ✅ Created regression test in `test/regression/issue/24147.test.ts` - ✅ Verified test fails with `USE_SYSTEM_BUN=1 bun test` (reproduces bug) - ✅ Verified test passes with `bun bd test` (confirms fix) - ✅ Test covers the exact reproduction case from the issue - ✅ Additional tests for edge cases (actual listeners, nested calls) 🤖 Generated with [Claude Code](https://claude.com/claude-code) --------- Co-authored-by: Claude Bot <claude-bot@bun.sh> Co-authored-by: Claude <noreply@anthropic.com>
82 lines
2.3 KiB
TypeScript
82 lines
2.3 KiB
TypeScript
// https://github.com/oven-sh/bun/issues/24147
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// EventEmitter: this._events becomes undefined when removeAllListeners()
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// called from event handler with removeListener meta-listener
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import { EventEmitter } from "events";
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import assert from "node:assert";
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import { test } from "node:test";
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test("removeAllListeners() from event handler with removeListener meta-listener", () => {
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const emitter = new EventEmitter();
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emitter.on("test", () => {
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// This should not crash even though there are no 'foo' listeners
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emitter.removeAllListeners("foo");
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});
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// Register a removeListener meta-listener to trigger the bug
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emitter.on("removeListener", () => {});
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// This should not throw
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assert.doesNotThrow(() => emitter.emit("test"));
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});
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test("removeAllListeners() with actual listeners to remove", () => {
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const emitter = new EventEmitter();
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let fooCallCount = 0;
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let removeListenerCallCount = 0;
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emitter.on("foo", () => fooCallCount++);
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emitter.on("foo", () => fooCallCount++);
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emitter.on("test", () => {
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// Remove all 'foo' listeners while inside an event handler
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emitter.removeAllListeners("foo");
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});
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// Track removeListener calls
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emitter.on("removeListener", () => {
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removeListenerCallCount++;
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});
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// Emit test event which triggers removeAllListeners
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emitter.emit("test");
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// Verify listeners were removed
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assert.strictEqual(emitter.listenerCount("foo"), 0);
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// Verify removeListener was called twice (once for each foo listener)
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assert.strictEqual(removeListenerCallCount, 2);
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// Verify foo listeners were never called
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assert.strictEqual(fooCallCount, 0);
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});
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test("nested removeAllListeners() calls", () => {
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const emitter = new EventEmitter();
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const events: string[] = [];
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emitter.on("outer", () => {
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events.push("outer-start");
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emitter.removeAllListeners("inner");
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events.push("outer-end");
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});
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emitter.on("inner", () => {
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events.push("inner");
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});
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emitter.on("removeListener", type => {
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events.push(`removeListener:${String(type)}`);
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});
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// This should not crash
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assert.doesNotThrow(() => emitter.emit("outer"));
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// Verify correct execution order
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assert.deepStrictEqual(events, ["outer-start", "removeListener:inner", "outer-end"]);
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// Verify inner listeners were removed
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assert.strictEqual(emitter.listenerCount("inner"), 0);
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});
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