fix: add 'limit' event to BusboyFileStream typings

README.md

@@ -41,7 +41,9 @@ Requirements
 Install
 =======
 
-    npm i @fastify/busboy
+```sh
+npm i @fastify/busboy
+```
 
 
 Examples
@@ -201,6 +203,16 @@ Busboy (special) events
     * If a configured file size limit was reached, `stream` will both have a boolean property `truncated` (best checked at the end of the stream) and emit a 'limit' event to notify you when this happens.
     * The property `bytesRead` informs about the number of bytes that have been read so far.
 
+* **limit**() - Emitted when a file exceeds the configured `fileSize` limit. You can listen on the file stream to handle it:
+
+```js
+busboy.on('file', (fieldname, stream) => {
+  stream.on('limit', () => {
+    console.log('File size exceeded')
+  })
+})
+```
+
 * **field**(< _string_ >fieldname, < _string_ >value, < _boolean_ >fieldnameTruncated, < _boolean_ >valueTruncated, < _string_ >transferEncoding, < _string_ >mimeType) - Emitted for each new non-file field found.
 
 * **partsLimit**() - Emitted when specified `parts` limit has been reached. No more 'file' or 'field' events will be emitted.

lib/main.d.ts

@@ -3,6 +3,17 @@
 //                 Igor Savin <https://github.com/kibertoad>
 
 /// <reference types="node" />
+declare module 'stream' {
+  interface Readable {
+    /**
+     * Emitted when the configured file size limit is reached.
+     */
+    on(event: 'limit', listener: () => void): this;
+    once(event: 'limit', listener: () => void): this;
+    addListener(event: 'limit', listener: () => void): this;
+    removeListener(event: 'limit', listener: () => void): this;
+  }
+}
 
 import * as http from 'node:http';
 import { Readable, Writable } from 'node:stream';

test/file-stream-limit.test.js

@@ -0,0 +1,39 @@
+'use strict'
+
+const { PassThrough } = require('stream')
+const Busboy = require('../').default
+const { test } = require('node:test')
+const assert = require('node:assert')
+
+test('BusboyFileStream emits limit', async (t) => {
+  await new Promise((resolve, reject) => {
+    const bigPayload = Buffer.alloc(20, 'a')
+    const boundary = 'foo'
+    const req = new PassThrough()
+    req.headers = {
+      'content-type': `multipart/form-data; boundary=${boundary}`
+    }
+
+    const bb = new Busboy({
+      headers: req.headers,
+      limits: { fileSize: 10 }
+    })
+
+    bb.on('file', (_fieldname, stream) => {
+      stream.on('limit', () => {
+        assert.ok(true, 'limit event emitted')
+        resolve()
+      })
+      stream.resume()
+    })
+
+    req.pipe(bb)
+
+    const delimiter = `--${boundary}`
+    req.write(`${delimiter}\r\n`)
+    req.write('Content-Disposition: form-data; name="file"; filename="a.txt"\r\n\r\n')
+    req.write(bigPayload)
+    req.write(`\r\n${delimiter}--\r\n`)
+    req.end()
+  })
+})