From 178784c22f67a9c36bffc1f963ec754864d5dc31 Mon Sep 17 00:00:00 2001
From: guoyangzhen <upgyz@qq.com>
Date: Mon, 16 Mar 2026 22:46:59 +0800
Subject: [PATCH] fix: prevent file handle leak when maxFiles is exceeded

Fixes #987

When maxFiles limit is reached, the fileBegin event handler calls _error(),
but _handlePart continues and opens a write stream for the new file.
These file handles are never closed.

Fix: check this.error after emitting fileBegin and before file.open().
If an error occurred (e.g., maxFiles exceeded), decrement _flushing
and return early to prevent the file stream from being opened.
---
 src/Formidable.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/Formidable.js b/src/Formidable.js
index 5ea964e0..2ade16e0 100644
--- a/src/Formidable.js
+++ b/src/Formidable.js
@@ -403,6 +403,12 @@ class IncomingForm extends EventEmitter {
     });
     this.emit('fileBegin', part.name, file);
 
+    // Check for error after fileBegin (e.g., maxFiles exceeded) to avoid leaking file handles
+    if (this.error) {
+      this._flushing -= 1;
+      return;
+    }
+
     file.open();
     this.openedFiles.push(file);